diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index 6040e68a17d..42d24cf34e7 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -84,18 +84,6 @@ parameters:
 			count: 2
 			path: wcfsetup/install/files/lib/data/comment/CommentAction.class.php
 
-		-
-			message: '#^Property wcf\\data\\comment\\response\\CommentResponseAction\:\:\$response \(wcf\\data\\comment\\response\\CommentResponse\) does not accept wcf\\data\\comment\\response\\CommentResponseEditor\.$#'
-			identifier: assign.propertyType
-			count: 1
-			path: wcfsetup/install/files/lib/data/comment/response/CommentResponseAction.class.php
-
-		-
-			message: '#^Property wcf\\data\\style\\StyleAction\:\:\$style \(wcf\\data\\style\\Style\) does not accept wcf\\data\\style\\StyleEditor\.$#'
-			identifier: assign.propertyType
-			count: 1
-			path: wcfsetup/install/files/lib/data/style/StyleAction.class.php
-
 		-
 			message: '#^While loop condition is always true\.$#'
 			identifier: while.alwaysTrue
@@ -108,18 +96,6 @@ parameters:
 			count: 1
 			path: wcfsetup/install/files/lib/form/LostPasswordForm.class.php
 
-		-
-			message: '#^Negated boolean expression is always true\.$#'
-			identifier: booleanNot.alwaysTrue
-			count: 1
-			path: wcfsetup/install/files/lib/page/AbstractPage.class.php
-
-		-
-			message: '#^Strict comparison using \=\=\= between int and ''og\:description'' will always evaluate to false\.$#'
-			identifier: identical.alwaysFalse
-			count: 1
-			path: wcfsetup/install/files/lib/page/AbstractPage.class.php
-
 		-
 			message: '#^Instanceof between wcf\\data\\search\\ISearchResultObject and wcf\\data\\search\\ISearchResultObject will always evaluate to true\.$#'
 			identifier: instanceof.alwaysTrue
@@ -402,12 +378,6 @@ parameters:
 			count: 1
 			path: wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php
 
-		-
-			message: '#^PHPDoc type array of property wcf\\system\\condition\\AbstractMultiSelectCondition\:\:\$fieldValue is not covariant with PHPDoc type string of overridden property wcf\\system\\condition\\AbstractSelectCondition\:\:\$fieldValue\.$#'
-			identifier: property.phpDocType
-			count: 1
-			path: wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php
-
 		-
 			message: '#^Parameter \#2 \$array of function implode expects array\|null, string given\.$#'
 			identifier: argument.type
@@ -780,12 +750,6 @@ parameters:
 			count: 2
 			path: wcfsetup/install/files/lib/system/form/builder/container/wysiwyg/WysiwygFormContainer.class.php
 
-		-
-			message: '#^Call to function is_array\(\) with array will always evaluate to true\.$#'
-			identifier: function.alreadyNarrowedType
-			count: 2
-			path: wcfsetup/install/files/lib/system/form/builder/data/FormDataHandler.class.php
-
 		-
 			message: '#^Call to function is_bool\(\) with string will always evaluate to false\.$#'
 			identifier: function.impossibleType
@@ -1017,7 +981,7 @@ parameters:
 		-
 			message: '#^Call to function is_numeric\(\) with float\|int will always evaluate to true\.$#'
 			identifier: function.alreadyNarrowedType
-			count: 7
+			count: 2
 			path: wcfsetup/install/files/lib/system/form/builder/field/UploadFormField.class.php
 
 		-
@@ -1045,7 +1009,7 @@ parameters:
 			path: wcfsetup/install/files/lib/system/form/builder/field/acl/AclFormField.class.php
 
 		-
-			message: '#^Instanceof between wcf\\data\\DatabaseObjectList and wcf\\data\\DatabaseObjectList will always evaluate to true\.$#'
+			message: '#^Instanceof between wcf\\data\\DatabaseObjectList<wcf\\data\\DatabaseObject> and wcf\\data\\DatabaseObjectList will always evaluate to true\.$#'
 			identifier: instanceof.alwaysTrue
 			count: 1
 			path: wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueFormFieldDependency.class.php
@@ -1183,7 +1147,7 @@ parameters:
 			path: wcfsetup/install/files/lib/system/label/object/AbstractLabelObjectHandler.class.php
 
 		-
-			message: '#^Call to an undefined method wcf\\data\\DatabaseObjectList\:\:getAttachmentList\(\)\.$#'
+			message: '#^Call to an undefined method wcf\\data\\DatabaseObjectList<wcf\\data\\DatabaseObject>\:\:getAttachmentList\(\)\.$#'
 			identifier: method.notFound
 			count: 1
 			path: wcfsetup/install/files/lib/system/message/QuickReplyManager.class.php
@@ -1293,13 +1257,13 @@ parameters:
 		-
 			message: '#^Call to function assert\(\) with true will always evaluate to true\.$#'
 			identifier: function.alreadyNarrowedType
-			count: 1
+			count: 2
 			path: wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php
 
 		-
 			message: '#^Instanceof between DOMElement and DOMElement will always evaluate to true\.$#'
 			identifier: instanceof.alwaysTrue
-			count: 1
+			count: 2
 			path: wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php
 
 		-
@@ -1311,13 +1275,13 @@ parameters:
 		-
 			message: '#^Call to function assert\(\) with true will always evaluate to true\.$#'
 			identifier: function.alreadyNarrowedType
-			count: 1
+			count: 2
 			path: wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php
 
 		-
 			message: '#^Instanceof between DOMElement and DOMElement will always evaluate to true\.$#'
 			identifier: instanceof.alwaysTrue
-			count: 1
+			count: 2
 			path: wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php
 
 		-
diff --git a/phpstan.neon b/phpstan.neon
index 48c845db327..8f7a3ea04e3 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -2,7 +2,7 @@ includes:
     - phpstan-baseline.neon
 
 parameters:
-    level: 5
+    level: 6
     paths:
         - wcfsetup/install/files
     excludePaths:
@@ -12,6 +12,7 @@ parameters:
         - constants.php
     ignoreErrors:
         - identifier: match.unhandled
+        - identifier: method.unused
         - identifier: new.static
         - identifier: trait.unused
     universalObjectCratesClasses:
diff --git a/wcfsetup/install/files/lib/acp/action/DashboardConfigureAction.class.php b/wcfsetup/install/files/lib/acp/action/DashboardConfigureAction.class.php
index eaa7e96cc22..d05ff336c79 100644
--- a/wcfsetup/install/files/lib/acp/action/DashboardConfigureAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/DashboardConfigureAction.class.php
@@ -24,6 +24,15 @@
 final class DashboardConfigureAction implements RequestHandlerInterface
 {
     private AcpDashboard $dashboard;
+
+    /**
+     * @var array<string, array{
+     *  boxName: string,
+     *  userID: int,
+     *  enabled: int,
+     *  showOrder: int,
+     * }>
+     */
     private array $userConfiguration;
 
     public function __construct()
@@ -88,6 +97,9 @@ private function getForm(): Psr15DialogForm
         return $form;
     }
 
+    /**
+     * @return list<string>
+     */
     private function getSelectedBoxNames(): array
     {
         $selectedBoxNames = [];
@@ -111,6 +123,9 @@ private function getConfigurationFormField(): MultipleSelectionFormField
         };
     }
 
+    /**
+     * @return array<string, string>
+     */
     private function getBoxOptions(): array
     {
         $options = [];
@@ -123,6 +138,9 @@ private function getBoxOptions(): array
         return $options;
     }
 
+    /**
+     * @param array<string, string> &$options
+     */
     private function sortBoxOptions(array &$options): void
     {
         \uksort($options, function (string $boxNameA, string $boxNameB) {
diff --git a/wcfsetup/install/files/lib/acp/action/FullLogoutAction.class.php b/wcfsetup/install/files/lib/acp/action/FullLogoutAction.class.php
index 4e2da709288..4ade49dd611 100644
--- a/wcfsetup/install/files/lib/acp/action/FullLogoutAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/FullLogoutAction.class.php
@@ -19,7 +19,7 @@ final class FullLogoutAction extends LogoutAction
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): RedirectResponse
     {
         AbstractSecureAction::execute();
 
diff --git a/wcfsetup/install/files/lib/acp/action/TagSynonymAction.class.php b/wcfsetup/install/files/lib/acp/action/TagSynonymAction.class.php
index 4cdf9912e25..987eb412756 100644
--- a/wcfsetup/install/files/lib/acp/action/TagSynonymAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/TagSynonymAction.class.php
@@ -81,6 +81,9 @@ public function handle(ServerRequestInterface $request): ResponseInterface
         }
     }
 
+    /**
+     * @param Tag[] $tags
+     */
     private function getForm(array $tags): Psr15DialogForm
     {
         $form = new Psr15DialogForm(
diff --git a/wcfsetup/install/files/lib/acp/action/UninstallPackageAction.class.php b/wcfsetup/install/files/lib/acp/action/UninstallPackageAction.class.php
index 168b1582632..c7e2d1067bb 100644
--- a/wcfsetup/install/files/lib/acp/action/UninstallPackageAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/UninstallPackageAction.class.php
@@ -75,7 +75,7 @@ public function readParameters()
         }
     }
 
-    public function execute()
+    public function execute(): ResponseInterface
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/acp/action/UserExportGdprAction.class.php b/wcfsetup/install/files/lib/acp/action/UserExportGdprAction.class.php
index e10f4e1bcc6..41943ca66dc 100644
--- a/wcfsetup/install/files/lib/acp/action/UserExportGdprAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/UserExportGdprAction.class.php
@@ -3,6 +3,7 @@
 namespace wcf\acp\action;
 
 use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
 use wcf\action\AbstractAction;
 use wcf\data\package\PackageCache;
 use wcf\data\user\cover\photo\DefaultUserCoverPhoto;
@@ -35,7 +36,7 @@ final class UserExportGdprAction extends AbstractAction
     /**
      * export data
      *
-     * @var array
+     * @var mixed[]
      */
     public $data = [];
 
@@ -149,7 +150,7 @@ public function readParameters()
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): ResponseInterface
     {
         // you MUST NOT use the `execute` event to provide data, use `export` (see below) instead!
         parent::execute();
@@ -249,7 +250,7 @@ public function execute()
      * @param string $ipAddressColumn
      * @param string $timeColumn
      * @param string $userIDColumn
-     * @return      array
+     * @return mixed[]
      */
     public function exportIpAddresses($databaseTable, $ipAddressColumn, $timeColumn, $userIDColumn)
     {
@@ -263,6 +264,11 @@ public function exportIpAddresses($databaseTable, $ipAddressColumn, $timeColumn,
         return $this->fetchIpAddresses($statement, $ipAddressColumn, $timeColumn);
     }
 
+    /**
+     * @param string $tableName
+     * @param string $userIDColumn
+     * @return mixed[]
+     */
     protected function dumpTable($tableName, $userIDColumn)
     {
         $sql = "SELECT  *
@@ -279,6 +285,11 @@ protected function dumpTable($tableName, $userIDColumn)
         return $data;
     }
 
+    /**
+     * @param string $ipAddressColumn
+     * @param string $timeColumn
+     * @return array{ipAddress: string, time: mixed}[]
+     */
     protected function fetchIpAddresses(PreparedStatement $statement, $ipAddressColumn, $timeColumn)
     {
         $ipAddresses = [];
@@ -297,6 +308,9 @@ protected function fetchIpAddresses(PreparedStatement $statement, $ipAddressColu
         return $ipAddresses;
     }
 
+    /**
+     * @return array{session: mixed[], acpSessionLog: mixed[]}
+     */
     protected function exportSessionIpAddresses()
     {
         $data = [
@@ -323,6 +337,9 @@ protected function exportSessionIpAddresses()
         return $data;
     }
 
+    /**
+     * @return array<string, mixed>
+     */
     protected function exportUser()
     {
         $data = ['languageCode' => $this->user->getLanguage()->getFixedLanguageCode()];
@@ -351,6 +368,9 @@ protected function exportUser()
         return $data;
     }
 
+    /**
+     * @return mixed[]
+     */
     protected function exportUserOptions()
     {
         $optionHandler = new UserOptionHandler(false, '', '');
@@ -365,6 +385,11 @@ protected function exportUserOptions()
         return $data;
     }
 
+    /**
+     * @param mixed[] &$data
+     * @param mixed[] $optionTree
+     * @return void
+     */
     protected function exportUserOptionCategory(array &$data, array $optionTree)
     {
         if (!empty($optionTree['options'])) {
diff --git a/wcfsetup/install/files/lib/acp/action/UserQuickSearchAction.class.php b/wcfsetup/install/files/lib/acp/action/UserQuickSearchAction.class.php
index 51adbbece62..6ae51316e1f 100644
--- a/wcfsetup/install/files/lib/acp/action/UserQuickSearchAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/UserQuickSearchAction.class.php
@@ -83,7 +83,7 @@ public function readParameters()
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): RedirectResponse
     {
         ACPMenu::getInstance()->setActiveMenuItem('wcf.acp.menu.link.user.search');
 
diff --git a/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php b/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
index 413e8c2abb7..f72c6d4d582 100644
--- a/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
@@ -32,7 +32,7 @@ final class WorkerProxyAction extends AJAXInvokeAction
 
     /**
      * parameters for worker action
-     * @var array
+     * @var array<string, mixed>
      */
     protected $parameters = [];
 
@@ -42,6 +42,9 @@ final class WorkerProxyAction extends AJAXInvokeAction
      */
     protected $worker;
 
+    /**
+     * @var string[]
+     */
     public static $allowInvoke = [];
 
     /**
@@ -66,6 +69,8 @@ public function readParameters()
 
     /**
      * Validates class name.
+     *
+     * @return void
      */
     protected function validate()
     {
@@ -112,8 +117,9 @@ public function execute()
      * Sends a JSON-encoded response.
      *
      * @param int $progress
-     * @param array $parameters
+     * @param ?array<string, mixed> $parameters
      * @param string $proceedURL
+     * @return void
      */
     protected function sendResponse($progress = 0, ?array $parameters = null, $proceedURL = '')
     {
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractAcpForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractAcpForm.class.php
index abf15ef171f..6f75514d1e2 100644
--- a/wcfsetup/install/files/lib/acp/form/AbstractAcpForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractAcpForm.class.php
@@ -34,7 +34,7 @@ abstract class AbstractAcpForm extends AbstractForm
     /**
      * Registers a new i18n value.
      *
-     * @param I18nValue $value
+     * @return void
      */
     public function registerI18nValue(I18nValue $value)
     {
@@ -106,7 +106,7 @@ public function validate()
     /**
      * Reads the i18n data for the given object.
      *
-     * @param DatabaseObject $databaseObject
+     * @return void
      */
     public function readDataI18n(DatabaseObject $databaseObject)
     {
@@ -159,8 +159,10 @@ public function beforeSaveI18n(DatabaseObject $databaseObject)
      * Saves the i18n data for the given database object after the given database
      * object has been created.
      *
-     * @param DatabaseObject $databaseObject
+     * @template TDatabaseObject of DatabaseObject
+     * @param TDatabaseObject $databaseObject
      * @param string $editorClass
+     * @return void
      */
     public function saveI18n(DatabaseObject $databaseObject, $editorClass)
     {
@@ -182,7 +184,7 @@ public function saveI18n(DatabaseObject $databaseObject, $editorClass)
         }
 
         if (!empty($data)) {
-            /** @var DatabaseObjectEditor $editor */
+            /** @var DatabaseObjectEditor<TDatabaseObject> $editor */
             $editor = new $editorClass($databaseObject);
             $editor->update($data);
         }
@@ -190,6 +192,8 @@ public function saveI18n(DatabaseObject $databaseObject, $editorClass)
 
     /**
      * Resets the form values and calls the saved event.
+     *
+     * @return void
      */
     public function reset()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractBulkProcessingForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractBulkProcessingForm.class.php
index 12ef7a56855..93d88428d73 100644
--- a/wcfsetup/install/files/lib/acp/form/AbstractBulkProcessingForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractBulkProcessingForm.class.php
@@ -42,6 +42,7 @@ abstract class AbstractBulkProcessingForm extends AbstractForm
     /**
      * list with bulk processed objects
      * @var \wcf\data\DatabaseObjectList
+     * @phpstan-ignore missingType.generics
      */
     public $objectList;
 
@@ -168,7 +169,10 @@ public function readFormParameters()
      */
     public function save()
     {
-        $this->objectList = $this->actions[$this->action]->getProcessor()->getObjectList();
+        $action = $this->actions[$this->action]->getProcessor();
+        \assert($action instanceof AbstractBulkProcessingAction);
+
+        $this->objectList = $action->getObjectList();
 
         parent::save();
 
@@ -182,8 +186,6 @@ public function save()
             }
         }
 
-        $action = $this->actions[$this->action]->getProcessor();
-        /** @var AbstractBulkProcessingAction $action */
         if ($action->canRunInWorker()) {
             $this->objectList->readObjectIDs();
 
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractCategoryAddForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractCategoryAddForm.class.php
index bcfa10476b5..e66f0a4a581 100644
--- a/wcfsetup/install/files/lib/acp/form/AbstractCategoryAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractCategoryAddForm.class.php
@@ -42,7 +42,7 @@ abstract class AbstractCategoryAddForm extends AbstractForm
 
     /**
      * additional category data
-     * @var array
+     * @var array<string, mixed>
      */
     public $additionalData = [];
 
@@ -173,6 +173,8 @@ public function assignVariables()
 
     /**
      * Checks if the active user has the needed permissions to add a new category.
+     *
+     * @return void
      */
     protected function checkCategoryPermissions()
     {
@@ -183,6 +185,8 @@ protected function checkCategoryPermissions()
 
     /**
      * Reads the categories.
+     *
+     * @return void
      */
     protected function readCategories()
     {
@@ -360,7 +364,7 @@ public function validate()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     protected function validateParentCategory()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractCustomOptionForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractCustomOptionForm.class.php
index 7edccad7ccd..1784a8eb19c 100644
--- a/wcfsetup/install/files/lib/acp/form/AbstractCustomOptionForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractCustomOptionForm.class.php
@@ -242,7 +242,7 @@ public function readData()
     /**
      * Returns the list of database values including additional fields.
      *
-     * @return      array
+     * @return array<string, mixed>
      */
     protected function getDatabaseValues()
     {
@@ -262,7 +262,8 @@ protected function getDatabaseValues()
     /**
      * Returns additional parameters passed to the database object action object.
      *
-     * @since       5.4
+     * @return array<string, mixed>
+     * @since 5.4
      */
     protected function getActionParameters(): array
     {
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractOptionListForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractOptionListForm.class.php
index ea015a4e4a4..f6bbb57d256 100755
--- a/wcfsetup/install/files/lib/acp/form/AbstractOptionListForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractOptionListForm.class.php
@@ -4,6 +4,7 @@
 
 use wcf\form\AbstractForm;
 use wcf\system\exception\UserInputException;
+use wcf\system\option\IOptionHandler;
 use wcf\system\option\OptionHandler;
 
 /**
@@ -12,6 +13,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template-covariant TOptionHandler of IOptionHandler
  */
 abstract class AbstractOptionListForm extends AbstractForm
 {
@@ -39,7 +42,8 @@ abstract class AbstractOptionListForm extends AbstractForm
 
     /**
      * option handler object
-     * @var \wcf\system\option\IOptionHandler
+     * @var TOptionHandler
+     * @phpstan-ignore generics.variance
      */
     public $optionHandler;
 
@@ -72,6 +76,8 @@ public function readParameters()
 
     /**
      * Initializes the option handler.
+     *
+     * @return void
      */
     protected function initOptionHandler()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/ApplicationManagementForm.class.php b/wcfsetup/install/files/lib/acp/form/ApplicationManagementForm.class.php
index d95609f2c4c..bb7f611f376 100644
--- a/wcfsetup/install/files/lib/acp/form/ApplicationManagementForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/ApplicationManagementForm.class.php
@@ -5,6 +5,7 @@
 use wcf\data\application\ViewableApplicationList;
 use wcf\data\page\Page;
 use wcf\data\page\PageList;
+use wcf\data\page\PageNode;
 use wcf\data\page\PageNodeTree;
 use wcf\form\AbstractForm;
 use wcf\system\application\ApplicationHandler;
@@ -61,7 +62,7 @@ final class ApplicationManagementForm extends AbstractForm
 
     /**
      * nested list of page nodes
-     * @var \RecursiveIteratorIterator
+     * @var \RecursiveIteratorIterator<PageNode>
      */
     public $pageNodeList;
 
diff --git a/wcfsetup/install/files/lib/acp/form/ArticleAddForm.class.php b/wcfsetup/install/files/lib/acp/form/ArticleAddForm.class.php
index 6024d06910a..94722df4c44 100644
--- a/wcfsetup/install/files/lib/acp/form/ArticleAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/ArticleAddForm.class.php
@@ -202,7 +202,7 @@ class ArticleAddForm extends AbstractForm
 
     /**
      * maps the label group ids to the article category ids
-     * @var array
+     * @var array<int, list<int>>
      */
     public $labelGroupsToCategories = [];
 
@@ -258,6 +258,8 @@ public function readParameters()
 
     /**
      * Reads basic article parameters controlling i18n.
+     *
+     * @return void
      */
     protected function readMultilingualSetting()
     {
@@ -352,6 +354,8 @@ public function readFormParameters()
 
     /**
      * Reads the box images.
+     *
+     * @return void
      */
     protected function readImages()
     {
@@ -477,6 +481,8 @@ public function validate()
 
     /**
      * Validates the selected labels.
+     *
+     * @return void
      */
     protected function validateLabelIDs()
     {
@@ -638,6 +644,8 @@ public function readData()
 
     /**
      * Sets the default values of properties.
+     *
+     * @return void
      */
     protected function setDefaultValues()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/BBCodeAddForm.class.php b/wcfsetup/install/files/lib/acp/form/BBCodeAddForm.class.php
index d42dfa63b2f..3d547ccac4d 100644
--- a/wcfsetup/install/files/lib/acp/form/BBCodeAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/BBCodeAddForm.class.php
@@ -157,6 +157,8 @@ public function readFormParameters()
 
     /**
      * Reads the form parameter for the button label.
+     *
+     * @return void
      */
     protected function readButtonLabelFormParameter()
     {
@@ -225,6 +227,8 @@ public function validate()
 
     /**
      * Validates the bbcode tag usage.
+     *
+     * @return void
      * @throws UserInputException
      */
     protected function validateBBCodeTagUsage()
diff --git a/wcfsetup/install/files/lib/acp/form/BoxAddForm.class.php b/wcfsetup/install/files/lib/acp/form/BoxAddForm.class.php
index cf5dc35ab78..c11c85c77a0 100644
--- a/wcfsetup/install/files/lib/acp/form/BoxAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/BoxAddForm.class.php
@@ -10,6 +10,7 @@
 use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\data\page\Page;
+use wcf\data\page\PageNode;
 use wcf\data\page\PageNodeTree;
 use wcf\data\smiley\SmileyCache;
 use wcf\form\AbstractForm;
@@ -173,13 +174,13 @@ class BoxAddForm extends AbstractForm
 
     /**
      * nested list of page nodes
-     * @var \RecursiveIteratorIterator
+     * @var \RecursiveIteratorIterator<PageNode>
      */
     public $pageNodeList;
 
     /**
      * acl values
-     * @var array
+     * @var mixed[]
      */
     public $aclValues = [];
 
@@ -195,7 +196,7 @@ class BoxAddForm extends AbstractForm
 
     /**
      * list of available positions per box handler
-     * @var array
+     * @var array<int, string[]>
      */
     public $availableBoxPositions = [];
 
@@ -275,6 +276,8 @@ public function readParameters()
 
     /**
      * Loads available box positions per box controller.
+     *
+     * @return void
      */
     protected function readBoxPositions()
     {
@@ -288,7 +291,8 @@ protected function readBoxPositions()
     /**
      * Reads basic page parameters controlling type and i18n.
      *
-     * @throws  IllegalLinkException
+     * @return void
+     * @throws IllegalLinkException
      */
     protected function readBoxType()
     {
@@ -412,6 +416,8 @@ private function readConditions(): void
 
     /**
      * Reads the box images.
+     *
+     * @return void
      */
     protected function readBoxImages()
     {
@@ -555,6 +561,8 @@ public function validate()
 
     /**
      * Validates box name.
+     *
+     * @return void
      */
     protected function validateName()
     {
@@ -568,6 +576,8 @@ protected function validateName()
 
     /**
      * Validates the selected box position.
+     *
+     * @return void
      */
     protected function validateBoxPosition()
     {
@@ -786,6 +796,9 @@ public function readData()
      * This is a helper method to convert groupedConditionObjectTypes to a flat list.
      * This method should not be used for any other purpose!
      *
+     * @template T of object
+     * @param T[]|T[][] $array
+     * @return T[]
      * @since 5.5
      */
     protected function toFlatList(array $array): array
diff --git a/wcfsetup/install/files/lib/acp/form/DataImportForm.class.php b/wcfsetup/install/files/lib/acp/form/DataImportForm.class.php
index 11b19e3f59f..ff1a9c17bb8 100644
--- a/wcfsetup/install/files/lib/acp/form/DataImportForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/DataImportForm.class.php
@@ -4,6 +4,7 @@
 
 use wcf\acp\action\CacheClearAction;
 use wcf\data\application\Application;
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\form\AbstractForm;
 use wcf\system\application\ApplicationHandler;
@@ -26,7 +27,7 @@ class DataImportForm extends AbstractForm
 {
     /**
      * additional data
-     * @var array
+     * @var mixed[]
      */
     public $additionalData = [];
 
@@ -42,7 +43,7 @@ class DataImportForm extends AbstractForm
 
     /**
      * list of available exporters
-     * @var array
+     * @var array<string, ObjectType>
      */
     public $exporters = [];
 
@@ -66,13 +67,13 @@ class DataImportForm extends AbstractForm
 
     /**
      * list of supported data types
-     * @var array
+     * @var array<string, string[]>
      */
     public $supportedData = [];
 
     /**
      * selected data types
-     * @var array
+     * @var string[]
      */
     public $selectedData = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectAddForm.class.php b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectAddForm.class.php
index d78540136df..be5d2f406fb 100644
--- a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectAddForm.class.php
@@ -1013,8 +1013,8 @@ public function save()
     /**
      * Writes the updated `package.xml` file for the given project using the given data.
      *
-     * @param DevtoolsProject $project
-     * @param array $data
+     * @param mixed[] $data
+     * @return void
      */
     protected function writePackageXml(DevtoolsProject $project, array $data)
     {
diff --git a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectEditForm.class.php b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectEditForm.class.php
index 35ec431286e..81cba14701f 100644
--- a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectEditForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectEditForm.class.php
@@ -255,7 +255,7 @@ protected function setFormObjectData()
             foreach ($requirements as $requirement) {
                 $requirementData[] = [
                     'file' => isset($requirement['file']) ? 1 : 0,
-                    'minVersion' => $requirement['minversion'] ?? '',
+                    'minVersion' => $requirement['minversion'],
                     'packageIdentifier' => $requirement['name'],
                 ];
             }
@@ -271,7 +271,7 @@ protected function setFormObjectData()
             foreach ($exclusions as $exclusion) {
                 $exclusionData[] = [
                     'packageIdentifier' => $exclusion['name'],
-                    'version' => $exclusion['version'] ?? '',
+                    'version' => $exclusion['version'],
                 ];
             }
 
@@ -334,6 +334,10 @@ protected function setFormObjectData()
         $instructionsField->value($instructions);
     }
 
+    /**
+     * @param bool $available
+     * @return void
+     */
     protected function tooglePackageXmlFieldAvailabilty($available)
     {
         /** @var TabMenuFormContainer $tabMenu */
diff --git a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectPipEntryAddForm.class.php b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectPipEntryAddForm.class.php
index 69c62c96eed..fdaec979789 100644
--- a/wcfsetup/install/files/lib/acp/form/DevtoolsProjectPipEntryAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/DevtoolsProjectPipEntryAddForm.class.php
@@ -132,6 +132,8 @@ public function createForm()
 
     /**
      * Adds the pip-specific form fields.
+     *
+     * @return void
      */
     protected function addPipFormFields()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsEmailForm.class.php b/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsEmailForm.class.php
index 68ce45f47b4..1ac27258b78 100644
--- a/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsEmailForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsEmailForm.class.php
@@ -19,7 +19,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.0
  *
- * @property OptionHandler $optionHandler
+ * @phpstan-import-type ParsedOption from OptionHandler
+ * @extends AbstractOptionListForm<OptionHandler>
  */
 final class FirstTimeSetupOptionsEmailForm extends AbstractOptionListForm
 {
@@ -30,7 +31,7 @@ final class FirstTimeSetupOptionsEmailForm extends AbstractOptionListForm
 
     /**
      * list of options
-     * @var array
+     * @var ParsedOption[]
      */
     public $options = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsForm.class.php b/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsForm.class.php
index 3c82c1b4298..3a54606bf59 100644
--- a/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/FirstTimeSetupOptionsForm.class.php
@@ -19,7 +19,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.0
  *
- * @property OptionHandler $optionHandler
+ * @phpstan-import-type ParsedOption from OptionHandler
+ * @extends AbstractOptionListForm<OptionHandler>
  */
 final class FirstTimeSetupOptionsForm extends AbstractOptionListForm
 {
@@ -30,7 +31,7 @@ final class FirstTimeSetupOptionsForm extends AbstractOptionListForm
 
     /**
      * list of options
-     * @var array
+     * @var ParsedOption[]
      */
     public $options = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/LabelGroupAddForm.class.php b/wcfsetup/install/files/lib/acp/form/LabelGroupAddForm.class.php
index e823faf0cef..32df844522b 100644
--- a/wcfsetup/install/files/lib/acp/form/LabelGroupAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/LabelGroupAddForm.class.php
@@ -66,7 +66,7 @@ class LabelGroupAddForm extends AbstractForm
 
     /**
      * list of label group to object type relations
-     * @var array<array>
+     * @var array<int, int[]>
      */
     public $objectTypes = [];
 
@@ -257,6 +257,7 @@ public function assignVariables()
      * Saves label group to object relations.
      *
      * @param ?int $groupID
+     * @return void
      */
     protected function saveObjectTypeRelations($groupID)
     {
@@ -299,7 +300,8 @@ protected function saveObjectTypeRelations($groupID)
     /**
      * Sets object type relations.
      *
-     * @param array|null $data
+     * @param ?array<int, int[]> $data
+     * @return void
      */
     protected function setObjectTypeRelations($data = null)
     {
diff --git a/wcfsetup/install/files/lib/acp/form/LanguageExportForm.class.php b/wcfsetup/install/files/lib/acp/form/LanguageExportForm.class.php
index aa5b9555de9..1c3318722ee 100644
--- a/wcfsetup/install/files/lib/acp/form/LanguageExportForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/LanguageExportForm.class.php
@@ -44,11 +44,13 @@ class LanguageExportForm extends AbstractForm
 
     /**
      * selected packages
+     * @var int
      */
     public $packageID = 0;
 
     /**
      * true to export custom variables
+     * @var bool
      */
     public $exportCustomValues = false;
 
@@ -82,7 +84,7 @@ public function readFormParameters()
         }
 
         if (isset($_POST['exportCustomValues'])) {
-            $this->exportCustomValues = \intval($_POST['exportCustomValues']);
+            $this->exportCustomValues = (bool)\intval($_POST['exportCustomValues']);
         }
         if (isset($_POST['languageID'])) {
             $this->languageID = \intval($_POST['languageID']);
diff --git a/wcfsetup/install/files/lib/acp/form/MenuItemAddForm.class.php b/wcfsetup/install/files/lib/acp/form/MenuItemAddForm.class.php
index 9ae376c4247..4c1c066acc1 100644
--- a/wcfsetup/install/files/lib/acp/form/MenuItemAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/MenuItemAddForm.class.php
@@ -62,6 +62,9 @@ class MenuItemAddForm extends AbstractFormBuilderForm
      */
     public Menu $menu;
 
+    /**
+     * @var \RecursiveIteratorIterator<MenuItemNode>
+     */
     public \RecursiveIteratorIterator $menuItemNodeList;
 
     /**
@@ -291,15 +294,31 @@ protected function setFormAction()
         );
     }
 
+    /**
+     * @param \RecursiveIteratorIterator<PageNode> $pageNodeList
+     * @param array<int, int> $pageHandlers
+     */
     protected function getPageObjectIDFormField(
         \RecursiveIteratorIterator $pageNodeList,
         array $pageHandlers
     ): IntegerFormField {
         return new class($pageNodeList, $pageHandlers) extends IntegerFormField {
             protected $templateName = '__pageObjectIDFormField';
+
+            /**
+             * @var array<int, int>
+             */
             protected array $pageHandlers;
+
+            /**
+             * @var \RecursiveIteratorIterator<PageNode>
+             */
             protected \RecursiveIteratorIterator $pageNodeList;
 
+            /**
+             * @param \RecursiveIteratorIterator<PageNode> $pageNodeList
+             * @param array<int, int> $pageHandlers
+             */
             public function __construct(\RecursiveIteratorIterator $pageNodeList, array $pageHandlers)
             {
                 parent::__construct();
diff --git a/wcfsetup/install/files/lib/acp/form/OptionForm.class.php b/wcfsetup/install/files/lib/acp/form/OptionForm.class.php
index e9d5ffac869..a1edfbb192e 100644
--- a/wcfsetup/install/files/lib/acp/form/OptionForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/OptionForm.class.php
@@ -7,6 +7,7 @@
 use wcf\system\application\ApplicationHandler;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\menu\acp\ACPMenu;
+use wcf\system\option\OptionHandler;
 use wcf\system\service\worker\ServiceWorkerHandler;
 use wcf\system\style\StyleHandler;
 use wcf\system\WCF;
@@ -17,6 +18,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends AbstractOptionListForm<OptionHandler>
  */
 class OptionForm extends AbstractOptionListForm
 {
@@ -34,7 +37,7 @@ class OptionForm extends AbstractOptionListForm
 
     /**
      * the option tree
-     * @var array
+     * @var mixed[]
      */
     public $optionTree = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/PackageEnableUpgradeOverrideForm.class.php b/wcfsetup/install/files/lib/acp/form/PackageEnableUpgradeOverrideForm.class.php
index 65456b4da69..99f7c369828 100644
--- a/wcfsetup/install/files/lib/acp/form/PackageEnableUpgradeOverrideForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PackageEnableUpgradeOverrideForm.class.php
@@ -84,7 +84,7 @@ protected function createForm()
         }
     }
 
-    private function isEnabled()
+    private function isEnabled(): bool
     {
         if (!isset($this->isEnabled)) {
             $this->isEnabled = PackageUpdateServer::isUpgradeOverrideEnabled();
@@ -93,7 +93,11 @@ private function isEnabled()
         return $this->isEnabled;
     }
 
-    private function getIssuesPreventingUpgrade()
+
+    /**
+     * @return list<array{title: string, description: string}>
+     */
+    private function getIssuesPreventingUpgrade(): array
     {
         $parameters = ['issues' => []];
         EventHandler::getInstance()->fireAction($this, 'getIssuesPreventingUpgrade', $parameters);
@@ -110,6 +114,9 @@ private function getIssuesPreventingUpgrade()
         return \array_filter($issues);
     }
 
+    /**
+     * @return ?array{title: string, description: string}
+     */
     private function checkMinimumPhpVersion(): ?array
     {
         // Minimum: PHP 8.1.2
@@ -130,6 +137,9 @@ private function checkMinimumPhpVersion(): ?array
         }
     }
 
+    /**
+     * @return ?array{title: string, description: string}
+     */
     private function checkMaximumPhpVersion(): ?array
     {
         // Maximum: PHP 8.3.x
@@ -150,6 +160,9 @@ private function checkMaximumPhpVersion(): ?array
         }
     }
 
+    /**
+     * @return ?array{title: string, description: string}
+     */
     private function checkRequiredPhpExtensions(): ?array
     {
         $requiredExtensions = [
@@ -195,6 +208,9 @@ private function checkRequiredPhpExtensions(): ?array
         }
     }
 
+    /**
+     * @return ?array{title: string, description: string}
+     */
     private function checkMinimumDatabaseVersion(): ?array
     {
         $sqlVersion = WCF::getDB()->getVersion();
@@ -232,6 +248,9 @@ private function checkMinimumDatabaseVersion(): ?array
         }
     }
 
+    /**
+     * @return ?array{title: string, description: string}
+     */
     private function checkForTls(): ?array
     {
         if (RouteHandler::secureConnection()) {
diff --git a/wcfsetup/install/files/lib/acp/form/PackageStartInstallForm.class.php b/wcfsetup/install/files/lib/acp/form/PackageStartInstallForm.class.php
index c15fa3a007d..c80119760e0 100755
--- a/wcfsetup/install/files/lib/acp/form/PackageStartInstallForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PackageStartInstallForm.class.php
@@ -123,6 +123,7 @@ public function validate()
      * Validates the upload package input.
      *
      * @param string $filename
+     * @return void
      * @throws  UserInputException
      */
     protected function validateUploadPackage($filename = '')
diff --git a/wcfsetup/install/files/lib/acp/form/PackageUpdateServerAddForm.class.php b/wcfsetup/install/files/lib/acp/form/PackageUpdateServerAddForm.class.php
index a537c07ceaa..f036ebd1a55 100755
--- a/wcfsetup/install/files/lib/acp/form/PackageUpdateServerAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PackageUpdateServerAddForm.class.php
@@ -3,6 +3,7 @@
 namespace wcf\acp\form;
 
 use Laminas\Diactoros\Uri;
+use wcf\data\package\update\server\PackageUpdateServer;
 use wcf\data\package\update\server\PackageUpdateServerAction;
 use wcf\data\package\update\server\PackageUpdateServerList;
 use wcf\form\AbstractForm;
@@ -79,6 +80,7 @@ public function validate()
     /**
      * Validates the server URL.
      *
+     * @return void
      * @since       5.3
      */
     protected function validateServerURL()
@@ -122,6 +124,7 @@ protected function validateServerURL()
     /**
      * Returns the first package update server with a matching serverURL.
      *
+     * @return ?PackageUpdateServer
      * @since       5.3
      */
     protected function findDuplicateServer()
@@ -133,6 +136,8 @@ protected function findDuplicateServer()
                 return $packageServer;
             }
         }
+
+        return null;
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/acp/form/PageAddForm.class.php b/wcfsetup/install/files/lib/acp/form/PageAddForm.class.php
index ee784dc3428..e8de035c58e 100644
--- a/wcfsetup/install/files/lib/acp/form/PageAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PageAddForm.class.php
@@ -139,7 +139,7 @@ class PageAddForm extends AbstractForm
 
     /**
      * acl values
-     * @var array
+     * @var mixed[]
      */
     public $aclValues = [];
 
@@ -245,6 +245,7 @@ public function readParameters()
     /**
      * Reads basic page parameters controlling type and i18n.
      *
+     * @return void
      * @throws  IllegalLinkException
      */
     protected function readPageType()
@@ -394,6 +395,8 @@ public function validate()
 
     /**
      * Validates page name.
+     *
+     * @return void
      */
     protected function validateName()
     {
@@ -408,6 +411,7 @@ protected function validateName()
     /**
      * Validates page type.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validatePageType()
@@ -424,6 +428,7 @@ protected function validatePageType()
     /**
      * Validates parent page id.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validateParentPageID()
@@ -443,6 +448,7 @@ protected function validateParentPageID()
     /**
      * Validates package id.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validateApplicationPackageID()
@@ -455,6 +461,7 @@ protected function validateApplicationPackageID()
     /**
      * Validates custom urls.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validateCustomUrls()
@@ -482,6 +489,7 @@ protected function validateCustomUrls()
      *
      * @param int $languageID
      * @param string $customURL
+     * @return void
      *
      * @throws  UserInputException
      */
@@ -524,6 +532,7 @@ protected function normalizeCustomUrl(string $customUrl): string
     /**
      * Validates page title.
      *
+     * @return void
      * @throws UserInputException
      */
     protected function validateTitle()
@@ -546,6 +555,7 @@ protected function validateTitle()
     /**
      * Validates parent menu item id.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validateParentMenuItemID()
@@ -561,6 +571,7 @@ protected function validateParentMenuItemID()
     /**
      * Validates box ids.
      *
+     * @return void
      * @throws  UserInputException
      */
     protected function validateBoxIDs()
diff --git a/wcfsetup/install/files/lib/acp/form/PageEditForm.class.php b/wcfsetup/install/files/lib/acp/form/PageEditForm.class.php
index b491580327d..7861a617ea9 100644
--- a/wcfsetup/install/files/lib/acp/form/PageEditForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PageEditForm.class.php
@@ -108,6 +108,9 @@ public function validate()
         $this->validateOverrideApplicationPackageID();
     }
 
+    /**
+     * @return void
+     */
     protected function validateOverrideApplicationPackageID()
     {
         if ($this->overrideApplicationPackageID) {
diff --git a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionAddForm.class.php b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionAddForm.class.php
index fd449076edf..923123889be 100644
--- a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionAddForm.class.php
@@ -119,7 +119,7 @@ class PaidSubscriptionAddForm extends AbstractForm
 
     /**
      * available user groups
-     * @var array
+     * @var UserGroup[]
      */
     public $availableUserGroups = [];
 
@@ -131,7 +131,7 @@ class PaidSubscriptionAddForm extends AbstractForm
 
     /**
      * list of available subscriptions
-     * @var array
+     * @var array<int, PaidSubscription>
      */
     public $availableSubscriptions = [];
 
@@ -169,6 +169,9 @@ public function readParameters()
         $this->getAvailableSubscriptions();
     }
 
+    /**
+     * @return void
+     */
     protected function getAvailableSubscriptions()
     {
         $subscriptionList = new PaidSubscriptionList();
@@ -340,6 +343,7 @@ public function save()
      *
      * @param PaidSubscription $subscription
      * @param string $columnName
+     * @return void
      */
     public function saveI18nValue(PaidSubscription $subscription, $columnName)
     {
diff --git a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionEditForm.class.php b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionEditForm.class.php
index dde638ed878..cad396e1f9f 100644
--- a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionEditForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionEditForm.class.php
@@ -72,6 +72,9 @@ public function readFormParameters()
         }
     }
 
+    /**
+     * @return void
+     */
     protected function getAvailableSubscriptions()
     {
         $subscriptionList = new PaidSubscriptionList();
diff --git a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionUserAddForm.class.php b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionUserAddForm.class.php
index 59bb7dd69a2..9e86f2946bb 100644
--- a/wcfsetup/install/files/lib/acp/form/PaidSubscriptionUserAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/PaidSubscriptionUserAddForm.class.php
@@ -118,6 +118,7 @@ public function validate()
     /**
      * Validates given username.
      *
+     * @return void
      * @throws UserInputException
      */
     protected function validateUsername()
@@ -134,6 +135,7 @@ protected function validateUsername()
     /**
      * Validates given end date.
      *
+     * @return void
      * @throws UserInputException
      */
     protected function validateEndDate()
@@ -195,6 +197,8 @@ public function readData()
 
     /**
      * Sets the default value for the end date.
+     *
+     * @return void
      */
     protected function setDefaultEndDate()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/RescueModeForm.class.php b/wcfsetup/install/files/lib/acp/form/RescueModeForm.class.php
index a52fdf8a5e3..81759e52777 100644
--- a/wcfsetup/install/files/lib/acp/form/RescueModeForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/RescueModeForm.class.php
@@ -62,6 +62,9 @@ final class RescueModeForm extends AbstractForm
      */
     public $username = '';
 
+    /**
+     * @var string
+     */
     public $domainName = '';
 
     private const ALLOWED_ATTEMPTS_PER_10M = 3;
@@ -72,6 +75,7 @@ final class RescueModeForm extends AbstractForm
 
     /**
      * @inheritDoc
+     * @phpstan-ignore return.unusedType
      */
     public function __run()
     {
@@ -160,6 +164,8 @@ public function readFormParameters()
 
     /**
      * Validates the user access data.
+     *
+     * @return void
      */
     protected function validateUser()
     {
@@ -215,6 +221,9 @@ private function validateDomainName(): void
         }
     }
 
+    /**
+     * @return void
+     */
     protected function validateApplications()
     {
         $usedPaths = [];
diff --git a/wcfsetup/install/files/lib/acp/form/SmileyAddForm.class.php b/wcfsetup/install/files/lib/acp/form/SmileyAddForm.class.php
index 9baff489cc9..ded2b151965 100644
--- a/wcfsetup/install/files/lib/acp/form/SmileyAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/SmileyAddForm.class.php
@@ -22,6 +22,15 @@
  * @author  Tim Duesterhus
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @phpstan-type FilesEntry array{
+ *  name: string,
+ *  type: string,
+ *  size: int,
+ *  tmp_name: string,
+ *  error: int,
+ *  full_path: string,
+ * }
  */
 class SmileyAddForm extends AbstractForm
 {
@@ -95,13 +104,13 @@ class SmileyAddForm extends AbstractForm
 
     /**
      * data of the uploaded smiley file
-     * @var array
+     * @var FilesEntry|array{}
      */
     public $fileUpload = [];
 
     /**
      * data of the uploaded smiley file (2x)
-     * @var array
+     * @var FilesEntry|array{}
      */
     public $fileUpload2x = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/StyleAddForm.class.php b/wcfsetup/install/files/lib/acp/form/StyleAddForm.class.php
index 37e985bc2a3..0b4b9ca014e 100644
--- a/wcfsetup/install/files/lib/acp/form/StyleAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/StyleAddForm.class.php
@@ -78,7 +78,7 @@ class StyleAddForm extends AbstractForm
 
     /**
      * list of available template groups
-     * @var TemplateGroup[]
+     * @var array<int, string>
      */
     public $availableTemplateGroups = [];
 
@@ -89,7 +89,7 @@ class StyleAddForm extends AbstractForm
     public $availableUnits = ['px', 'pt', 'rem', 'em', '%'];
 
     /**
-     * @var array
+     * @var array<string, string|string[]>
      */
     public $colorCategories = [];
 
@@ -107,7 +107,7 @@ class StyleAddForm extends AbstractForm
 
     /**
      * list of global variables
-     * @var array
+     * @var string[]
      */
     public $globals = [];
 
@@ -233,6 +233,7 @@ public function readParameters()
     }
 
     /**
+     * @return array<string, mixed[]>
      * @since   5.3
      */
     protected function getUploadFields()
@@ -279,6 +280,7 @@ protected function getUploadFields()
     }
 
     /**
+     * @return void
      * @since   5.3
      */
     protected function rebuildUploadFields()
@@ -419,6 +421,7 @@ public function readFormParameters()
     }
 
     /**
+     * @return void
      * @since   5.3
      */
     protected function downloadGoogleFont()
@@ -501,6 +504,8 @@ public function validate()
 
     /**
      * Validates the individual scss.
+     *
+     * @return void
      * @throws      UserInputException
      * @since       5.3
      */
@@ -531,6 +536,7 @@ public function validateIndividualScss()
     /**
      * Disallow the use of `com.woltlab.*` for package names to avoid accidental collisions.
      *
+     * @return void
      * @throws      UserInputException
      */
     protected function enforcePackageNameRestriction()
@@ -542,6 +548,7 @@ protected function enforcePackageNameRestriction()
     }
 
     /**
+     * @return void
      * @since   5.3
      */
     protected function validateUploads()
@@ -620,6 +627,7 @@ protected function validateUploads()
      * the style editor itself, it will be silently discarded.
      *
      * @param string $variableName
+     * @return void
      * @throws      UserInputException
      */
     protected function parseOverrides($variableName = 'overrideScss')
@@ -720,6 +728,8 @@ public function readData()
 
     /**
      * Sets available variables
+     *
+     * @return void
      */
     protected function setVariables()
     {
@@ -820,6 +830,8 @@ protected function setVariables()
 
     /**
      * Reads style variable values.
+     *
+     * @return void
      */
     protected function readStyleVariables()
     {
@@ -953,6 +965,9 @@ public function assignVariables()
         ]);
     }
 
+    /**
+     * @return void
+     */
     protected function setDefaultValues()
     {
         $this->authorName = WCF::getUser()->username;
diff --git a/wcfsetup/install/files/lib/acp/form/TrophyAddForm.class.php b/wcfsetup/install/files/lib/acp/form/TrophyAddForm.class.php
index f4e9ac31f51..5ba22be8b67 100644
--- a/wcfsetup/install/files/lib/acp/form/TrophyAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/TrophyAddForm.class.php
@@ -278,6 +278,8 @@ public function validate()
 
     /**
      * Validates the trophy type.
+     *
+     * @return void
      */
     protected function validateType()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserAddForm.class.php b/wcfsetup/install/files/lib/acp/form/UserAddForm.class.php
index 0221ce34da6..5acc47a47d6 100644
--- a/wcfsetup/install/files/lib/acp/form/UserAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserAddForm.class.php
@@ -3,6 +3,7 @@
 namespace wcf\acp\form;
 
 use wcf\data\smiley\category\SmileyCategory;
+use wcf\data\smiley\Smiley;
 use wcf\data\smiley\SmileyCache;
 use wcf\data\user\group\UserGroup;
 use wcf\data\user\User;
@@ -114,18 +115,27 @@ class UserAddForm extends UserOptionListForm
 
     /**
      * tree of available user options
-     * @var array
+     * @var mixed[]
      */
     public $optionTree = [];
+
     public AttachmentHandler $attachmentHandler;
+
     public int $attachmentObjectID = 0;
+
     public string $attachmentObjectType = 'com.woltlab.wcf.user.signature';
+
+    /**
+     * @var array<int, Smiley>
+     */
     public array $defaultSmilies = [];
+
     /**
      * list of smiley categories
-     * @var SmileyCategory[]
+     * @var array<int, SmileyCategory>
      */
     public array $smileyCategories = [];
+
     public ?string $tmpHash = '';
 
     #[\Override]
@@ -341,7 +351,6 @@ public function save()
         $this->signature = $this->disableSignatureReason = '';
         $this->groupIDs = [];
         $this->languageID = $this->getDefaultFormLanguageID();
-        \assert($this->optionHandler instanceof UserOptionHandler);
         $this->optionHandler->resetOptionValues();
         // Reload attachment handler to reset the uploaded attachments.
         $this->attachmentHandler = new AttachmentHandler(
@@ -355,7 +364,8 @@ public function save()
      * Throws a UserInputException if the username is not unique or not valid.
      *
      * @param string $username
-     * @throws  UserInputException
+     * @return void
+     * @throws UserInputException
      */
     protected function validateUsername($username)
     {
@@ -376,7 +386,7 @@ protected function validateUsername($username)
 
     /**
      * Throws a UserInputException if the email is not unique or not valid.
-     * @throws  UserInputException
+     * @throws UserInputException
      */
     protected function validateEmail(string $email): void
     {
@@ -397,7 +407,7 @@ protected function validateEmail(string $email): void
 
     /**
      * Throws a UserInputException if the password is not valid.
-     * @throws  UserInputException
+     * @throws UserInputException
      */
     protected function validatePassword(
         #[\SensitiveParameter]
@@ -437,6 +447,8 @@ public function readData()
 
     /**
      * Reads option tree on page init.
+     *
+     * @return void
      */
     protected function readOptionTree()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserAssignToGroupForm.class.php b/wcfsetup/install/files/lib/acp/form/UserAssignToGroupForm.class.php
index 0267fbcfb34..b2d6ef9a397 100755
--- a/wcfsetup/install/files/lib/acp/form/UserAssignToGroupForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserAssignToGroupForm.class.php
@@ -79,6 +79,7 @@ public function readParameters()
         }
 
         // get user
+        // @phpstan-ignore assign.propertyType
         $this->users = ClipboardHandler::getInstance()->getMarkedItems($this->objectTypeID);
         if (empty($this->users)) {
             throw new IllegalLinkException();
@@ -195,6 +196,8 @@ public function assignVariables()
 
     /**
      * Get a list of available groups.
+     *
+     * @return void
      */
     protected function readGroups()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserContentRevertChangesForm.class.php b/wcfsetup/install/files/lib/acp/form/UserContentRevertChangesForm.class.php
index afbfe3de976..ba52190b7d4 100644
--- a/wcfsetup/install/files/lib/acp/form/UserContentRevertChangesForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserContentRevertChangesForm.class.php
@@ -68,6 +68,7 @@ public function readParameters()
         // get object type id
         $this->objectTypeID = ClipboardHandler::getInstance()->getObjectTypeID('com.woltlab.wcf.user');
         // get user
+        // @phpstan-ignore assign.propertyType
         $this->users = ClipboardHandler::getInstance()->getMarkedItems($this->objectTypeID);
         if (empty($this->users)) {
             throw new IllegalLinkException();
diff --git a/wcfsetup/install/files/lib/acp/form/UserEditForm.class.php b/wcfsetup/install/files/lib/acp/form/UserEditForm.class.php
index f3df9310d42..a7df8b4936d 100755
--- a/wcfsetup/install/files/lib/acp/form/UserEditForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserEditForm.class.php
@@ -191,7 +191,6 @@ public function readParameters()
      */
     protected function initOptionHandler()
     {
-        \assert($this->optionHandler instanceof UserOptionHandler);
         $this->optionHandler->setUser($this->user->getDecoratedObject());
     }
 
@@ -310,6 +309,8 @@ public function readData()
 
     /**
      * Sets the selected languages.
+     *
+     * @return void
      */
     protected function readVisibleLanguages()
     {
@@ -318,6 +319,8 @@ protected function readVisibleLanguages()
 
     /**
      * Sets the default values.
+     *
+     * @return void
      */
     protected function readDefaultValues()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserEmailAddressExportForm.class.php b/wcfsetup/install/files/lib/acp/form/UserEmailAddressExportForm.class.php
index 447e6133a40..1a98f90eedf 100755
--- a/wcfsetup/install/files/lib/acp/form/UserEmailAddressExportForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserEmailAddressExportForm.class.php
@@ -81,6 +81,7 @@ public function readParameters()
 
         // get user ids
         $users = ClipboardHandler::getInstance()->getMarkedItems($this->objectTypeID);
+        /** @var User[] $users */
         if (empty($users)) {
             throw new IllegalLinkException();
         }
diff --git a/wcfsetup/install/files/lib/acp/form/UserGroupAddForm.class.php b/wcfsetup/install/files/lib/acp/form/UserGroupAddForm.class.php
index 692a68a745d..553d7b31bdf 100755
--- a/wcfsetup/install/files/lib/acp/form/UserGroupAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserGroupAddForm.class.php
@@ -17,7 +17,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
- * @property-read UserGroupOptionHandler $optionHandler
+ *
+ * @extends AbstractOptionListForm<UserGroupOptionHandler>
  */
 class UserGroupAddForm extends AbstractOptionListForm
 {
@@ -33,7 +34,7 @@ class UserGroupAddForm extends AbstractOptionListForm
 
     /**
      * option tree
-     * @var array
+     * @var mixed[]
      */
     public $optionTree = [];
 
@@ -60,8 +61,8 @@ class UserGroupAddForm extends AbstractOptionListForm
     protected $groupDescription = '';
 
     /**
-     * list of values of group 'Anyone'
-     * @var array
+     * list of values of group 'Everyone'
+     * @var mixed[]
      */
     public $defaultValues = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/UserGroupOptionForm.class.php b/wcfsetup/install/files/lib/acp/form/UserGroupOptionForm.class.php
index 36fa7307656..0493a7e10fb 100644
--- a/wcfsetup/install/files/lib/acp/form/UserGroupOptionForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserGroupOptionForm.class.php
@@ -62,7 +62,7 @@ class UserGroupOptionForm extends AbstractForm
 
     /**
      * list of values per user group
-     * @var array
+     * @var mixed[]
      */
     public $values = [];
 
diff --git a/wcfsetup/install/files/lib/acp/form/UserMergeForm.class.php b/wcfsetup/install/files/lib/acp/form/UserMergeForm.class.php
index 07089a90343..4433ac50ddd 100644
--- a/wcfsetup/install/files/lib/acp/form/UserMergeForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserMergeForm.class.php
@@ -73,11 +73,13 @@ public function readParameters()
         // get object type id
         $this->objectTypeID = ClipboardHandler::getInstance()->getObjectTypeID('com.woltlab.wcf.user');
         // get user
+        // @phpstan-ignore assign.propertyType
         $this->users = ClipboardHandler::getInstance()->getMarkedItems($this->objectTypeID);
         if (empty($this->users) || \count($this->users) < 2) {
             throw new IllegalLinkException();
         }
         foreach ($this->users as $user) {
+            /** @var User $user */
             if (!$user->canEdit()) {
                 throw new PermissionDeniedException();
             }
diff --git a/wcfsetup/install/files/lib/acp/form/UserOptionListForm.class.php b/wcfsetup/install/files/lib/acp/form/UserOptionListForm.class.php
index c5c07a1fc76..f9ed0a0929f 100644
--- a/wcfsetup/install/files/lib/acp/form/UserOptionListForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserOptionListForm.class.php
@@ -12,6 +12,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends AbstractOptionListForm<UserOptionHandler>
  */
 abstract class UserOptionListForm extends AbstractOptionListForm
 {
@@ -28,7 +30,7 @@ abstract class UserOptionListForm extends AbstractOptionListForm
     /**
      * Returns a list of all available user groups.
      *
-     * @return  UserGroup[]
+     * @return UserGroup[]
      */
     protected function getAvailableGroups()
     {
@@ -38,7 +40,7 @@ protected function getAvailableGroups()
     /**
      * Returns the default form language id.
      *
-     * @return  int     $languageID
+     * @return int $languageID
      */
     protected function getDefaultFormLanguageID()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserSearchForm.class.php b/wcfsetup/install/files/lib/acp/form/UserSearchForm.class.php
index d639b8b96af..a48913eb9b9 100755
--- a/wcfsetup/install/files/lib/acp/form/UserSearchForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserSearchForm.class.php
@@ -283,6 +283,8 @@ public function validate()
 
     /**
      * Search for users which fit to the search values.
+     *
+     * @return void
      */
     protected function search()
     {
diff --git a/wcfsetup/install/files/lib/acp/form/UserTrophyAddForm.class.php b/wcfsetup/install/files/lib/acp/form/UserTrophyAddForm.class.php
index 00bb51d5574..ee6d0f6738c 100644
--- a/wcfsetup/install/files/lib/acp/form/UserTrophyAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/UserTrophyAddForm.class.php
@@ -124,6 +124,7 @@ public function readFormParameters()
     /**
      * Validates the users.
      *
+     * @return void
      * @throws UserInputException
      */
     protected function validateUser()
diff --git a/wcfsetup/install/files/lib/acp/page/ACPSessionLogListPage.class.php b/wcfsetup/install/files/lib/acp/page/ACPSessionLogListPage.class.php
index 4ad0070947f..96037913d86 100755
--- a/wcfsetup/install/files/lib/acp/page/ACPSessionLogListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ACPSessionLogListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\ACPSessionLogGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ACPSessionLogGridView    $gridView
+ * @extends AbstractGridViewPage<ACPSessionLogGridView>
  */
 class ACPSessionLogListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class ACPSessionLogListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.management.canViewLog'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): ACPSessionLogGridView
     {
         return new ACPSessionLogGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/ACPSessionLogPage.class.php b/wcfsetup/install/files/lib/acp/page/ACPSessionLogPage.class.php
index 065273cbd73..97ce50d313b 100755
--- a/wcfsetup/install/files/lib/acp/page/ACPSessionLogPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ACPSessionLogPage.class.php
@@ -5,7 +5,6 @@
 use wcf\data\acp\session\log\ACPSessionLog;
 use wcf\page\AbstractGridViewPage;
 use wcf\system\exception\IllegalLinkException;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\ACPSessionGridView;
 use wcf\system\request\LinkHandler;
 use wcf\system\WCF;
@@ -17,7 +16,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ACPSessionGridView $gridView
+ * @extends AbstractGridViewPage<ACPSessionGridView>
  */
 class ACPSessionLogPage extends AbstractGridViewPage
 {
@@ -64,7 +63,7 @@ public function assignVariables()
     }
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): ACPSessionGridView
     {
         return new ACPSessionGridView($this->sessionLog->sessionLogID);
     }
diff --git a/wcfsetup/install/files/lib/acp/page/AbstractCategoryListPage.class.php b/wcfsetup/install/files/lib/acp/page/AbstractCategoryListPage.class.php
index 7620d484e41..a7a75aade74 100644
--- a/wcfsetup/install/files/lib/acp/page/AbstractCategoryListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/AbstractCategoryListPage.class.php
@@ -116,6 +116,8 @@ public function assignVariables()
 
     /**
      * Checks if the active user has the needed permissions to view this list.
+     *
+     * @return void
      */
     protected function checkCategoryPermissions()
     {
@@ -126,6 +128,8 @@ protected function checkCategoryPermissions()
 
     /**
      * Reads the categories.
+     *
+     * @return void
      */
     protected function readCategories()
     {
diff --git a/wcfsetup/install/files/lib/acp/page/AdListPage.class.php b/wcfsetup/install/files/lib/acp/page/AdListPage.class.php
index 3870e1a5acc..f6a02694bbf 100644
--- a/wcfsetup/install/files/lib/acp/page/AdListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/AdListPage.class.php
@@ -12,7 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    AdList $objectList
+ * @extends MultipleLinkPage<AdList>
  */
 class AdListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/ArticleListPage.class.php b/wcfsetup/install/files/lib/acp/page/ArticleListPage.class.php
index a3ede997721..74ef7564308 100644
--- a/wcfsetup/install/files/lib/acp/page/ArticleListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ArticleListPage.class.php
@@ -15,7 +15,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @property    ArticleGridView $gridView
+ * @extends AbstractGridViewPage<ArticleGridView>
  */
 class ArticleListPage extends AbstractGridViewPage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/AttachmentListPage.class.php b/wcfsetup/install/files/lib/acp/page/AttachmentListPage.class.php
index 6e74bf4fbe6..4c44fc9a189 100644
--- a/wcfsetup/install/files/lib/acp/page/AttachmentListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/AttachmentListPage.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    AttachmentGridView $gridView
+ * @extends AbstractGridViewPage<AttachmentGridView>
  */
 class AttachmentListPage extends AbstractGridViewPage
 {
@@ -43,6 +43,9 @@ public function assignVariables()
         ]);
     }
 
+    /**
+     * @return array{count: int, size: int, downloads: int}
+     */
     private function getAttachmentStats(): array
     {
         $sql = "SELECT  COUNT(*) AS count,
diff --git a/wcfsetup/install/files/lib/acp/page/BBCodeListPage.class.php b/wcfsetup/install/files/lib/acp/page/BBCodeListPage.class.php
index dc8e40fee97..ade791f0d24 100644
--- a/wcfsetup/install/files/lib/acp/page/BBCodeListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/BBCodeListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\BBCodeGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    BBCodeGridView $gridView
+ * @extends AbstractGridViewPage<BBCodeGridView>
  */
 class BBCodeListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class BBCodeListPage extends AbstractGridViewPage
     public $templateName = 'bbcodeList';
 
     #[\Override]
-    public function createGridView(): AbstractGridView
+    public function createGridView(): BBCodeGridView
     {
         return new BBCodeGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/BBCodeMediaProviderListPage.class.php b/wcfsetup/install/files/lib/acp/page/BBCodeMediaProviderListPage.class.php
index 536dc5e6f72..8dd26828c46 100644
--- a/wcfsetup/install/files/lib/acp/page/BBCodeMediaProviderListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/BBCodeMediaProviderListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\BBCodeMediaProviderGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    BBCodeMediaProviderGridView $gridView
+ * @extends AbstractGridViewPage<BBCodeMediaProviderGridView>
  */
 class BBCodeMediaProviderListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class BBCodeMediaProviderListPage extends AbstractGridViewPage
     public $templateName = 'bbcodeMediaProviderList';
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): BBCodeMediaProviderGridView
     {
         return new BBCodeMediaProviderGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/BoxListPage.class.php b/wcfsetup/install/files/lib/acp/page/BoxListPage.class.php
index 930c84213a3..151bccc07c0 100644
--- a/wcfsetup/install/files/lib/acp/page/BoxListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/BoxListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\BoxGridView;
 use wcf\system\language\LanguageFactory;
 use wcf\system\WCF;
@@ -16,7 +15,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @property    BoxGridView $gridView
+ * @extends AbstractGridViewPage<BoxGridView>
  */
 class BoxListPage extends AbstractGridViewPage
 {
@@ -58,7 +57,7 @@ public function assignVariables()
     }
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): BoxGridView
     {
         return new BoxGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/CacheListPage.class.php b/wcfsetup/install/files/lib/acp/page/CacheListPage.class.php
index 6a63871bed7..ba9611735da 100755
--- a/wcfsetup/install/files/lib/acp/page/CacheListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/CacheListPage.class.php
@@ -35,13 +35,24 @@ class CacheListPage extends AbstractPage
 
     /**
      * contains a list of cache resources
-     * @var array
+     * @var array<string, array<string, list<array{
+     *  filename: string,
+     *  filesize: int,
+     *  mtime: int,
+     *  perm: string,
+     *  writeable: bool,
+     * }>>>
      */
     public $caches = [];
 
     /**
      * contains general cache information
-     * @var array
+     * @var array{
+     *  source: string,
+     *  version: string,
+     *  size: int,
+     *  files: int,
+     * }|array{}
      */
     public $cacheData = [];
 
@@ -109,8 +120,9 @@ public function readData()
      *
      * @param string $cacheType
      * @param string $cacheDir
-     * @param Regex $ignore
+     * @param ?Regex $ignore
      * @param string $extension
+     * @return void
      */
     protected function readCacheFiles($cacheType, $cacheDir, ?Regex $ignore = null, $extension = 'php')
     {
diff --git a/wcfsetup/install/files/lib/acp/page/CaptchaQuestionListPage.class.php b/wcfsetup/install/files/lib/acp/page/CaptchaQuestionListPage.class.php
index 8cf265fbd21..a3759f9cb57 100644
--- a/wcfsetup/install/files/lib/acp/page/CaptchaQuestionListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/CaptchaQuestionListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\CaptchaQuestionGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    CaptchaQuestionGridView $gridView
+ * @extends AbstractGridViewPage<CaptchaQuestionGridView>
  */
 class CaptchaQuestionListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class CaptchaQuestionListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.captcha.canManageCaptchaQuestion'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): CaptchaQuestionGridView
     {
         return new CaptchaQuestionGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/CronjobListPage.class.php b/wcfsetup/install/files/lib/acp/page/CronjobListPage.class.php
index 3649363db09..323ccbd2b5a 100755
--- a/wcfsetup/install/files/lib/acp/page/CronjobListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/CronjobListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\CronjobGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    CronjobGridView $gridView
+ * @extends AbstractGridViewPage<CronjobGridView>
  */
 class CronjobListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class CronjobListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.management.canManageCronjob'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): CronjobGridView
     {
         return new CronjobGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/CronjobLogListPage.class.php b/wcfsetup/install/files/lib/acp/page/CronjobLogListPage.class.php
index 04f116c97c0..75e7d8bc948 100755
--- a/wcfsetup/install/files/lib/acp/page/CronjobLogListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/CronjobLogListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\CronjobLogGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    CronjobLogGridView    $gridView
+ * @extends AbstractGridViewPage<CronjobLogGridView>
  */
 class CronjobLogListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class CronjobLogListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.management.canManageCronjob'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): CronjobLogGridView
     {
         return new CronjobLogGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/DevtoolsMissingLanguageItemListPage.class.php b/wcfsetup/install/files/lib/acp/page/DevtoolsMissingLanguageItemListPage.class.php
index 631d493a926..24431ce301d 100644
--- a/wcfsetup/install/files/lib/acp/page/DevtoolsMissingLanguageItemListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/DevtoolsMissingLanguageItemListPage.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
+ *
+ * @extends SortablePage<DevtoolsMissingLanguageItemList>
  */
 class DevtoolsMissingLanguageItemListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/DevtoolsProjectListPage.class.php b/wcfsetup/install/files/lib/acp/page/DevtoolsProjectListPage.class.php
index e512a0b7aab..27f7684fd87 100644
--- a/wcfsetup/install/files/lib/acp/page/DevtoolsProjectListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/DevtoolsProjectListPage.class.php
@@ -13,7 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @property    DevtoolsProjectList $objectList
+ * @extends SortablePage<DevtoolsProjectList>
  */
 class DevtoolsProjectListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/EmailLogListPage.class.php b/wcfsetup/install/files/lib/acp/page/EmailLogListPage.class.php
index ed2a149ad39..d0c3e9c4230 100644
--- a/wcfsetup/install/files/lib/acp/page/EmailLogListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/EmailLogListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\EmailLogGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    EmailLogGridView $gridView
+ * @extends AbstractGridViewPage<EmailLogGridView>
  */
 class EmailLogListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class EmailLogListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.management.canViewLog'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): EmailLogGridView
     {
         return new EmailLogGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/ExceptionLogViewPage.class.php b/wcfsetup/install/files/lib/acp/page/ExceptionLogViewPage.class.php
index 431f7c4b610..33e1fc1c675 100644
--- a/wcfsetup/install/files/lib/acp/page/ExceptionLogViewPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ExceptionLogViewPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\ExceptionLogGridView;
 use wcf\system\registry\RegistryHandler;
 
@@ -13,6 +12,8 @@
  * @author  Tim Duesterhus
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends AbstractGridViewPage<ExceptionLogGridView>
  */
 class ExceptionLogViewPage extends AbstractGridViewPage
 {
@@ -40,7 +41,7 @@ private function markNotificationsAsRead(): void
     }
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): ExceptionLogGridView
     {
         return new ExceptionLogGridView(true);
     }
diff --git a/wcfsetup/install/files/lib/acp/page/LabelGroupListPage.class.php b/wcfsetup/install/files/lib/acp/page/LabelGroupListPage.class.php
index 5e10f5d7314..d3639e8a1b8 100644
--- a/wcfsetup/install/files/lib/acp/page/LabelGroupListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/LabelGroupListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\LabelGroupGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    LabelGroupGridView $gridView
+ * @extends AbstractGridViewPage<LabelGroupGridView>
  */
 class LabelGroupListPage extends AbstractGridViewPage
 {
@@ -23,7 +22,7 @@ class LabelGroupListPage extends AbstractGridViewPage
     public $activeMenuItem = 'wcf.acp.menu.link.label.group.list';
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): LabelGroupGridView
     {
         return new LabelGroupGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/LabelListPage.class.php b/wcfsetup/install/files/lib/acp/page/LabelListPage.class.php
index 45e1d1e6029..80c4e0b50de 100644
--- a/wcfsetup/install/files/lib/acp/page/LabelListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/LabelListPage.class.php
@@ -21,7 +21,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    LabelList $objectList
+ * @extends SortablePage<LabelList>
  */
 class LabelListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/LanguageItemListPage.class.php b/wcfsetup/install/files/lib/acp/page/LanguageItemListPage.class.php
index f75ab803f94..9149bca5306 100644
--- a/wcfsetup/install/files/lib/acp/page/LanguageItemListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/LanguageItemListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\LanguageItemGridView;
 use wcf\system\WCF;
 
@@ -14,7 +13,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property LanguageItemGridView $gridView
+ * @extends AbstractGridViewPage<LanguageItemGridView>
  */
 class LanguageItemListPage extends AbstractGridViewPage
 {
@@ -29,7 +28,7 @@ class LanguageItemListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.language.canManageLanguage'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): LanguageItemGridView
     {
         return new LanguageItemGridView(WCF::getLanguage());
     }
diff --git a/wcfsetup/install/files/lib/acp/page/LanguageListPage.class.php b/wcfsetup/install/files/lib/acp/page/LanguageListPage.class.php
index 1aafad4fb46..a1ccea7be49 100644
--- a/wcfsetup/install/files/lib/acp/page/LanguageListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/LanguageListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\LanguageGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    LanguageGridView $gridView
+ * @extends AbstractGridViewPage<LanguageGridView>
  */
 class LanguageListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class LanguageListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.language.canManageLanguage'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): LanguageGridView
     {
         return new LanguageGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/LicensePage.class.php b/wcfsetup/install/files/lib/acp/page/LicensePage.class.php
index fd2f754cf5c..2d40910b7db 100644
--- a/wcfsetup/install/files/lib/acp/page/LicensePage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/LicensePage.class.php
@@ -35,18 +35,34 @@ final class LicensePage extends AbstractPage
 
     private LicenseData $licenseData;
 
+    /**
+     * @var array<string, array<string, string>>
+     */
     private array $availablePackages = [];
 
+    /**
+     * @var array<string, Package>
+     */
     private array $installedPackages;
 
+    /**
+     * @var array<string|int, mixed>
+     */
     private array $installablePackages = [];
 
+    /**
+     * @var array<string, PackageUpdate>
+     */
     private array $packageUpdates = [];
 
+    /**
+     * @var array<string, string>
+     */
     private array $requiresLicenseExtension = [];
 
     private const CURRENT_MAJOR = '6.0';
 
+    #[\Override]
     public function readData()
     {
         parent::readData();
@@ -143,6 +159,7 @@ function (string $package) {
         }
     }
 
+    #[\Override]
     public function assignVariables()
     {
         parent::assignVariables();
@@ -158,6 +175,7 @@ public function assignVariables()
     }
 
     /**
+     * @param string[] $identifiers
      * @return array<string, Package>
      */
     private function getInstalledPackages(array $identifiers): array
@@ -183,6 +201,10 @@ private function getInstalledPackages(array $identifiers): array
         return $packages;
     }
 
+    /**
+     * @param string[] $identifiers
+     * @return string[]
+     */
     private function removeUnknownPackages(array $identifiers): array
     {
         if ($identifiers === []) {
@@ -201,6 +223,7 @@ private function removeUnknownPackages(array $identifiers): array
     }
 
     /**
+     * @param string[] $packages
      * @return array<string, PackageUpdate>
      */
     private function getPackageUpdates(array $packages): array
@@ -221,7 +244,12 @@ private function getPackageUpdates(array $packages): array
         return $packageUpdates;
     }
 
-    // Stolen from PackageUpdateAction::search() and slightly modified.
+    /**
+     * Stolen from PackageUpdateAction::search() and slightly modified.
+     *
+     * @param string[] $identifiers
+     * @return array<string|int, mixed>
+     */
     private function getInstallablePackages(array $identifiers): array
     {
         $availableUpdateServers = \array_filter(
diff --git a/wcfsetup/install/files/lib/acp/page/MediaListPage.class.php b/wcfsetup/install/files/lib/acp/page/MediaListPage.class.php
index 568d3c503ae..8e26e6505d2 100644
--- a/wcfsetup/install/files/lib/acp/page/MediaListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/MediaListPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\acp\page;
 
+use wcf\data\category\CategoryNode;
 use wcf\data\category\CategoryNodeTree;
 use wcf\data\media\ViewableMediaList;
 use wcf\page\SortablePage;
@@ -18,7 +19,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @property    ViewableMediaList $objectList
+ * @extends SortablePage<ViewableMediaList>
  */
 class MediaListPage extends SortablePage
 {
@@ -35,7 +36,7 @@ class MediaListPage extends SortablePage
 
     /**
      * node tree with all available media categories
-     * @var \RecursiveIteratorIterator
+     * @var \RecursiveIteratorIterator<CategoryNode>
      */
     public $categoryList;
 
diff --git a/wcfsetup/install/files/lib/acp/page/MenuListPage.class.php b/wcfsetup/install/files/lib/acp/page/MenuListPage.class.php
index fc0491cd621..44f330d43ba 100644
--- a/wcfsetup/install/files/lib/acp/page/MenuListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/MenuListPage.class.php
@@ -2,9 +2,7 @@
 
 namespace wcf\acp\page;
 
-use wcf\data\menu\MenuList;
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\MenuGridView;
 
 /**
@@ -15,7 +13,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       3.0
  *
- * @property    MenuList $objectList
+ * @extends AbstractGridViewPage<MenuGridView>
  */
 class MenuListPage extends AbstractGridViewPage
 {
@@ -30,7 +28,7 @@ class MenuListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.content.cms.canManageMenu'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): MenuGridView
     {
         return new MenuGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/ModificationLogListPage.class.php b/wcfsetup/install/files/lib/acp/page/ModificationLogListPage.class.php
index 2eaba4ef54d..65a2e8a4c69 100644
--- a/wcfsetup/install/files/lib/acp/page/ModificationLogListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ModificationLogListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\ModificationLogGridView;
 
 /**
@@ -13,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ModificationLogGridView    $gridView
  * @since       5.2
+ * @extends AbstractGridViewPage<ModificationLogGridView>
  */
 class ModificationLogListPage extends AbstractGridViewPage
 {
@@ -29,7 +28,7 @@ class ModificationLogListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.management.canViewLog'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): ModificationLogGridView
     {
         return new ModificationLogGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/NoticeListPage.class.php b/wcfsetup/install/files/lib/acp/page/NoticeListPage.class.php
index a9944435b4c..f61d91c45fd 100644
--- a/wcfsetup/install/files/lib/acp/page/NoticeListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/NoticeListPage.class.php
@@ -12,7 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    NoticeList $objectList
+ * @extends SortablePage<NoticeList>
  */
 class NoticeListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/PackageListPage.class.php b/wcfsetup/install/files/lib/acp/page/PackageListPage.class.php
index c39498a2592..b543c5999a3 100644
--- a/wcfsetup/install/files/lib/acp/page/PackageListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PackageListPage.class.php
@@ -16,7 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    I18nPackageList $objectList
+ * @extends SortablePage<I18nPackageList>
  */
 class PackageListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/PackagePage.class.php b/wcfsetup/install/files/lib/acp/page/PackagePage.class.php
index 6b4aa753c45..56339e4d335 100755
--- a/wcfsetup/install/files/lib/acp/page/PackagePage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PackagePage.class.php
@@ -22,6 +22,7 @@ class PackagePage extends AbstractPage
     public $activeMenuItem = 'wcf.acp.menu.link.package.list';
 
     /**
+     * @var array{}
      * @deprecated 5.5 This array is always empty.
      */
     public $compatibleVersions = [];
diff --git a/wcfsetup/install/files/lib/acp/page/PackageUpdatePage.class.php b/wcfsetup/install/files/lib/acp/page/PackageUpdatePage.class.php
index cef2a762f90..c196d58e943 100644
--- a/wcfsetup/install/files/lib/acp/page/PackageUpdatePage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PackageUpdatePage.class.php
@@ -23,7 +23,7 @@ class PackageUpdatePage extends AbstractPage
 
     /**
      * list of available updates
-     * @var array
+     * @var mixed[]
      */
     public $availableUpdates = [];
 
diff --git a/wcfsetup/install/files/lib/acp/page/PackageUpdateServerListPage.class.php b/wcfsetup/install/files/lib/acp/page/PackageUpdateServerListPage.class.php
index aea90eaf81e..8a1d3765bdd 100755
--- a/wcfsetup/install/files/lib/acp/page/PackageUpdateServerListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PackageUpdateServerListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\PackageUpdateServerGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    PackageUpdateServerGridView $gridView
+ * @extends AbstractGridViewPage<PackageUpdateServerGridView>
  */
 class PackageUpdateServerListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class PackageUpdateServerListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.configuration.package.canEditServer'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): PackageUpdateServerGridView
     {
         return new PackageUpdateServerGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/PageListPage.class.php b/wcfsetup/install/files/lib/acp/page/PageListPage.class.php
index ef153809267..7b129a5fa14 100644
--- a/wcfsetup/install/files/lib/acp/page/PageListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PageListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\PageGridView;
 use wcf\system\language\LanguageFactory;
 use wcf\system\WCF;
@@ -16,7 +15,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       3.0
  *
- * @property    PageGridView $gridView
+ * @extends AbstractGridViewPage<PageGridView>
  */
 class PageListPage extends AbstractGridViewPage
 {
@@ -58,7 +57,7 @@ public function assignVariables()
     }
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): PageGridView
     {
         return new PageGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionListPage.class.php b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionListPage.class.php
index 3d8b7ce5060..242e3994a0b 100644
--- a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\PaidSubscriptionGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    PaidSubscriptionGridView $gridView
+ * @extends AbstractGridViewPage<PaidSubscriptionGridView>
  */
 class PaidSubscriptionListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class PaidSubscriptionListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.paidSubscription.canManageSubscription'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): PaidSubscriptionGridView
     {
         return new PaidSubscriptionGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogListPage.class.php b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogListPage.class.php
index 0660032c323..371e8aae96e 100644
--- a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\PaidSubscriptionTransactionLogGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    PaidSubscriptionTransactionLogGridView $gridView
+ * @extends AbstractGridViewPage<PaidSubscriptionTransactionLogGridView>
  */
 class PaidSubscriptionTransactionLogListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class PaidSubscriptionTransactionLogListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.paidSubscription.canManageSubscription'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): PaidSubscriptionTransactionLogGridView
     {
         return new PaidSubscriptionTransactionLogGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogPage.class.php b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogPage.class.php
index 491577609b9..c694a9cbb5e 100644
--- a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionTransactionLogPage.class.php
@@ -39,7 +39,7 @@ class PaidSubscriptionTransactionLogPage extends AbstractPage
 
     /**
      * log entry object
-     * @var\wcf\data\paid\subscription\transaction\log\PaidSubscriptionTransactionLog
+     * @var PaidSubscriptionTransactionLog
      */
     public $log;
 
diff --git a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionUserListPage.class.php b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionUserListPage.class.php
index 0ccd7d0affe..11c6b66491c 100644
--- a/wcfsetup/install/files/lib/acp/page/PaidSubscriptionUserListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/PaidSubscriptionUserListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\PaidSubscriptionUserGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    PaidSubscriptionUserGridView $gridView
+ * @extends AbstractGridViewPage<PaidSubscriptionUserGridView>
  */
 class PaidSubscriptionUserListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class PaidSubscriptionUserListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.paidSubscription.canManageSubscription'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): PaidSubscriptionUserGridView
     {
         return new PaidSubscriptionUserGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/ReactionTypeListPage.class.php b/wcfsetup/install/files/lib/acp/page/ReactionTypeListPage.class.php
index e7fd3017a91..5d1114bd05d 100644
--- a/wcfsetup/install/files/lib/acp/page/ReactionTypeListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/ReactionTypeListPage.class.php
@@ -12,7 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ReactionTypeList $objectList
+ * @extends MultipleLinkPage<ReactionTypeList>
  */
 class ReactionTypeListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php b/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
index ae81802179f..8ac7cb77cca 100644
--- a/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/RebuildDataPage.class.php
@@ -6,6 +6,7 @@
 use wcf\page\AbstractPage;
 use wcf\system\event\EventHandler;
 use wcf\system\WCF;
+use wcf\system\worker\RegisteredWorker;
 
 /**
  * Show the list of available rebuild data options.
@@ -27,7 +28,7 @@ final class RebuildDataPage extends AbstractPage
     public $neededPermissions = ['admin.management.canRebuildData'];
 
     /**
-     * @var iterable
+     * @var iterable<RegisteredWorker>
      */
     private iterable $workers;
 
diff --git a/wcfsetup/install/files/lib/acp/page/SmileyListPage.class.php b/wcfsetup/install/files/lib/acp/page/SmileyListPage.class.php
index 4e813538b15..9e0c5272902 100644
--- a/wcfsetup/install/files/lib/acp/page/SmileyListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/SmileyListPage.class.php
@@ -17,7 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    SmileyList $objectList
+ * @extends MultipleLinkPage<SmileyList>
  */
 class SmileyListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/StatPage.class.php b/wcfsetup/install/files/lib/acp/page/StatPage.class.php
index e28685cd38f..d491b673a9a 100644
--- a/wcfsetup/install/files/lib/acp/page/StatPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/StatPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\acp\page;
 
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\page\AbstractPage;
 use wcf\system\WCF;
@@ -40,7 +41,7 @@ class StatPage extends AbstractPage
 
     /**
      * available object type
-     * @var array
+     * @var array<string, list<ObjectType>>
      */
     public $availableObjectTypes = [];
 
diff --git a/wcfsetup/install/files/lib/acp/page/StyleListPage.class.php b/wcfsetup/install/files/lib/acp/page/StyleListPage.class.php
index 56688f1afe2..427123357a4 100644
--- a/wcfsetup/install/files/lib/acp/page/StyleListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/StyleListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\StyleGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    StyleGridView    $gridView
+ * @extends AbstractGridViewPage<StyleGridView>
  */
 class StyleListPage  extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class StyleListPage  extends AbstractGridViewPage
     public $neededPermissions = ['admin.style.canManageStyle'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): StyleGridView
     {
         return new StyleGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/SystemCheckPage.class.php b/wcfsetup/install/files/lib/acp/page/SystemCheckPage.class.php
index fcaf91fbab6..891dd9a41bf 100644
--- a/wcfsetup/install/files/lib/acp/page/SystemCheckPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/SystemCheckPage.class.php
@@ -33,7 +33,7 @@ class SystemCheckPage extends AbstractPage
     /**
      * A list of directories that need to be writable at all times, grouped by their application
      * identifier. Only the directory itself is checked, unless the path ends with `/*`.
-     * @var string[][]
+     * @var array<string, list<string>>
      */
     public $directories = [
         'wcf' => [
@@ -53,6 +53,12 @@ class SystemCheckPage extends AbstractPage
         ],
     ];
 
+    /**
+     * @var array{
+     *  mysql: array<string|int, string>,
+     *  mariadb: array<string|int, string>,
+     * }
+     */
     public $mysqlVersions = [
         'mysql' => [
             '8' => '8.0.30',
@@ -62,6 +68,9 @@ class SystemCheckPage extends AbstractPage
         ],
     ];
 
+    /**
+     * @var list<string|list<string>>
+     */
     public $phpExtensions = [
         'ctype',
         'dom',
@@ -76,8 +85,19 @@ class SystemCheckPage extends AbstractPage
         'zlib',
     ];
 
+    /**
+     * @var int
+     */
     public $phpMemoryLimit = 128 * 1024 * 1024;
 
+    /**
+     * @var array{
+     *  minimum: string,
+     *  deprecated: list<string>,
+     *  sufficient: list<string>,
+     *  recommended: list<string>,
+     * }
+     */
     public $phpVersions = [
         'minimum' => '8.1.2',
         'deprecated' => [],
@@ -85,6 +105,9 @@ class SystemCheckPage extends AbstractPage
         'recommended' => ['8.2', '8.3'],
     ];
 
+    /**
+     * @var array<string, array<string, array<string, string>>>
+     */
     public $foreignKeys = [
         'wcf1_user' => [
             'avatarFileID' => [
@@ -118,6 +141,9 @@ class SystemCheckPage extends AbstractPage
         ],
     ];
 
+    /**
+     * @var mixed[]
+     */
     public $results = [
         'directories' => [],
         'mysql' => [
@@ -221,6 +247,9 @@ public function assignVariables()
         ]);
     }
 
+    /**
+     * @return void
+     */
     protected function validateMysql()
     {
         // check sql version
@@ -312,6 +341,9 @@ protected function validateMysql()
         }
     }
 
+    /**
+     * @return void
+     */
     protected function validatePhpExtensions()
     {
         foreach ($this->phpExtensions as $phpExtension) {
@@ -339,6 +371,9 @@ protected function validatePhpExtensions()
             && $this->results['php']['opcache'] !== false;
     }
 
+    /**
+     * @return void
+     */
     protected function validatePhpMemoryLimit()
     {
         $this->results['php']['memoryLimit']['required'] = $this->phpMemoryLimit;
@@ -357,6 +392,9 @@ protected function validatePhpMemoryLimit()
         $this->results['status']['php'] = $this->results['status']['php'] && $this->results['php']['memoryLimit']['result'];
     }
 
+    /**
+     * @return void
+     */
     protected function validatePhpX64()
     {
         $this->results['php']['x64'] = \PHP_INT_SIZE == 8;
@@ -364,6 +402,9 @@ protected function validatePhpX64()
         $this->results['status']['php'] = $this->results['status']['php'] && $this->results['php']['x64'];
     }
 
+    /**
+     * @return void
+     */
     protected function validatePhpVersion()
     {
         $phpVersion = \PHP_VERSION;
@@ -387,6 +428,9 @@ protected function validatePhpVersion()
         $this->results['status']['php'] = $this->results['status']['php'] && ($this->results['php']['version']['result'] !== 'unsupported');
     }
 
+    /**
+     * @return void
+     */
     protected function validatePhpGdSupport()
     {
         if (!\function_exists('\gd_info')) {
@@ -407,6 +451,9 @@ protected function validatePhpGdSupport()
         $this->results['status']['php'] = $this->results['status']['php'] && $this->results['php']['gd']['result'];
     }
 
+    /**
+     * @return void
+     */
     protected function validateWritableDirectories()
     {
         foreach ($this->directories as $abbreviation => $directories) {
@@ -423,6 +470,10 @@ protected function validateWritableDirectories()
         $this->results['status']['directories'] = empty($this->results['directories']);
     }
 
+    /**
+     * @param string $path
+     * @return bool
+     */
     protected function checkDirectory($path)
     {
         if (!$this->createDirectoryIfNotExists($path)) {
@@ -434,6 +485,10 @@ protected function checkDirectory($path)
         return $this->makeDirectoryWritable($path);
     }
 
+    /**
+     * @param string $path
+     * @return bool
+     */
     protected function createDirectoryIfNotExists($path)
     {
         if (!\file_exists($path) && !FileUtil::makePath($path)) {
@@ -447,6 +502,10 @@ protected function createDirectoryIfNotExists($path)
         return true;
     }
 
+    /**
+     * @param string $path
+     * @return bool
+     */
     protected function makeDirectoryWritable($path)
     {
         try {
diff --git a/wcfsetup/install/files/lib/acp/page/TagListPage.class.php b/wcfsetup/install/files/lib/acp/page/TagListPage.class.php
index 47e821d8e50..9401e9a2c5f 100644
--- a/wcfsetup/install/files/lib/acp/page/TagListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/TagListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\TagGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    TagGridView $gridView
+ * @extends AbstractGridViewPage<TagGridView>
  */
 class TagListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class TagListPage extends AbstractGridViewPage
     public $neededModules = ['MODULE_TAGGING'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): TagGridView
     {
         return new TagGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/TemplateDiffPage.class.php b/wcfsetup/install/files/lib/acp/page/TemplateDiffPage.class.php
index 40995ac164d..1b2cd66edc9 100644
--- a/wcfsetup/install/files/lib/acp/page/TemplateDiffPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/TemplateDiffPage.class.php
@@ -52,7 +52,7 @@ class TemplateDiffPage extends AbstractPage
 
     /**
      * differences between both templates
-     * @var array
+     * @var mixed[]
      */
     public $diff;
 
diff --git a/wcfsetup/install/files/lib/acp/page/TemplateGroupListPage.class.php b/wcfsetup/install/files/lib/acp/page/TemplateGroupListPage.class.php
index f3b6b774687..058696cb196 100644
--- a/wcfsetup/install/files/lib/acp/page/TemplateGroupListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/TemplateGroupListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\TemplateGroupGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    TemplateGroupGridView $gridView
+ * @extends AbstractGridViewPage<TemplateGroupGridView>
  */
 class TemplateGroupListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class TemplateGroupListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.template.canManageTemplate'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): TemplateGroupGridView
     {
         return new TemplateGroupGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/TemplateListPage.class.php b/wcfsetup/install/files/lib/acp/page/TemplateListPage.class.php
index 8c02081d630..a3faaadf85f 100644
--- a/wcfsetup/install/files/lib/acp/page/TemplateListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/TemplateListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\TemplateGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    TemplateGridView $gridView
+ * @extends AbstractGridViewPage<TemplateGridView>
  */
 class TemplateListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class TemplateListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.template.canManageTemplate'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): TemplateGridView
     {
         return new TemplateGridView(TemplateGridView::DEFAULT_TEMPLATE_GROUP_ID);
     }
diff --git a/wcfsetup/install/files/lib/acp/page/TrophyListPage.class.php b/wcfsetup/install/files/lib/acp/page/TrophyListPage.class.php
index 8723f3b26c8..716a5fe5bdb 100644
--- a/wcfsetup/install/files/lib/acp/page/TrophyListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/TrophyListPage.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends MultipleLinkPage<TrophyList>
  */
 class TrophyListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/UserAuthenticationFailureListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserAuthenticationFailureListPage.class.php
index ea9b1d61027..53c8f23f5b8 100644
--- a/wcfsetup/install/files/lib/acp/page/UserAuthenticationFailureListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserAuthenticationFailureListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\UserAuthenticationFailureGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserAuthenticationFailureGridView $gridView
+ * @extends AbstractGridViewPage<UserAuthenticationFailureGridView>
  */
 class UserAuthenticationFailureListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class UserAuthenticationFailureListPage extends AbstractGridViewPage
     public $neededModules = ['ENABLE_USER_AUTHENTICATION_FAILURE'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): UserAuthenticationFailureGridView
     {
         return new UserAuthenticationFailureGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/UserGroupAssignmentListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserGroupAssignmentListPage.class.php
index 010adf14610..a1973a8c309 100644
--- a/wcfsetup/install/files/lib/acp/page/UserGroupAssignmentListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserGroupAssignmentListPage.class.php
@@ -2,9 +2,7 @@
 
 namespace wcf\acp\page;
 
-use wcf\data\user\group\assignment\UserGroupAssignmentList;
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\UserGroupAssignmentGridView;
 
 /**
@@ -14,7 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserGroupAssignmentList $objectList
+ * @extends AbstractGridViewPage<UserGroupAssignmentGridView>
  */
 class UserGroupAssignmentListPage extends AbstractGridViewPage
 {
@@ -29,7 +27,7 @@ class UserGroupAssignmentListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.user.canManageGroupAssignment'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): UserGroupAssignmentGridView
     {
         return new UserGroupAssignmentGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/UserGroupListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserGroupListPage.class.php
index cfb1bbc61f1..08ba8c6fd82 100755
--- a/wcfsetup/install/files/lib/acp/page/UserGroupListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserGroupListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\UserGroupGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserGroupGridView $gridView
+ * @extends AbstractGridViewPage<UserGroupGridView>
  */
 class UserGroupListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class UserGroupListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.user.canEditGroup', 'admin.user.canDeleteGroup'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): UserGroupGridView
     {
         return new UserGroupGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/UserListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserListPage.class.php
index e87312076d8..f45b5c5ef20 100755
--- a/wcfsetup/install/files/lib/acp/page/UserListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserListPage.class.php
@@ -2,7 +2,10 @@
 
 namespace wcf\acp\page;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\user\group\UserGroup;
+use wcf\data\user\option\UserOption;
 use wcf\data\user\option\ViewableUserOption;
 use wcf\data\user\User;
 use wcf\data\user\UserProfile;
@@ -25,6 +28,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends SortablePage<DatabaseObjectList<DatabaseObject>>
  */
 class UserListPage extends SortablePage
 {
@@ -42,7 +47,7 @@ class UserListPage extends SortablePage
 
     /**
      * applies special CSS classes for selected columns
-     * @var array
+     * @var array<string, string>
      */
     public $columnStyling = [
         'registrationDate' => 'columnDate',
@@ -87,7 +92,7 @@ class UserListPage extends SortablePage
 
     /**
      * list of available user option names
-     * @var array
+     * @var array<string, ViewableUserOption>
      */
     public $options = [];
 
@@ -253,6 +258,8 @@ public function countItems()
 
     /**
      * Fetches the list of results.
+     *
+     * @return void
      */
     protected function readUsers()
     {
@@ -367,6 +374,8 @@ protected function readUsers()
 
     /**
      * Fetches the result of the search with the given search id.
+     *
+     * @return void
      */
     protected function readSearchResult()
     {
@@ -396,19 +405,21 @@ protected function readSearchResult()
 
     /**
      * Fetches the user options from cache.
+     *
+     * @return void
      */
     protected function readUserOptions()
     {
-        $this->options = UserOptionCacheBuilder::getInstance()->getData([], 'options');
-
-        foreach ($this->options as &$option) {
-            $option = new ViewableUserOption($option);
-        }
-        unset($option);
+        $this->options = \array_map(
+            static fn(UserOption $option) => new ViewableUserOption($option),
+            UserOptionCacheBuilder::getInstance()->getData([], 'options')
+        );
     }
 
     /**
      * Reads the column heads.
+     *
+     * @return void
      */
     protected function readColumnsHeads()
     {
diff --git a/wcfsetup/install/files/lib/acp/page/UserOptionCategoryListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserOptionCategoryListPage.class.php
index 2841acf31fc..b60940d9ebf 100644
--- a/wcfsetup/install/files/lib/acp/page/UserOptionCategoryListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserOptionCategoryListPage.class.php
@@ -12,7 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserOptionCategoryList $objectList
+ * @extends SortablePage<UserOptionCategoryList>
  */
 class UserOptionCategoryListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/UserOptionListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserOptionListPage.class.php
index eae6dbb669a..36c74b993b8 100644
--- a/wcfsetup/install/files/lib/acp/page/UserOptionListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserOptionListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\UserOptionGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserOptionGridView    $gridView
+ * @extends AbstractGridViewPage<UserOptionGridView>
  */
 class UserOptionListPage extends AbstractGridViewPage
 {
@@ -28,7 +27,7 @@ class UserOptionListPage extends AbstractGridViewPage
     public $neededPermissions = ['admin.user.canManageUserOption'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): UserOptionGridView
     {
         return new UserOptionGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/UserRankListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserRankListPage.class.php
index 076ffb6487c..79a541125a3 100644
--- a/wcfsetup/install/files/lib/acp/page/UserRankListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserRankListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\acp\page;
 
 use wcf\page\AbstractGridViewPage;
-use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\admin\UserRankGridView;
 
 /**
@@ -13,7 +12,7 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserRankGridView    $gridView
+ * @extends AbstractGridViewPage<UserRankGridView>
  */
 class UserRankListPage extends AbstractGridViewPage
 {
@@ -33,7 +32,7 @@ class UserRankListPage extends AbstractGridViewPage
     public $neededModules = ['MODULE_USER_RANK'];
 
     #[\Override]
-    protected function createGridView(): AbstractGridView
+    protected function createGridView(): UserRankGridView
     {
         return new UserRankGridView();
     }
diff --git a/wcfsetup/install/files/lib/acp/page/UserTrophyListPage.class.php b/wcfsetup/install/files/lib/acp/page/UserTrophyListPage.class.php
index 00d6f30dace..40f596d42a3 100644
--- a/wcfsetup/install/files/lib/acp/page/UserTrophyListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/UserTrophyListPage.class.php
@@ -16,6 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends SortablePage<UserTrophyList>
  */
 class UserTrophyListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/acp/page/VersionTrackerListPage.class.php b/wcfsetup/install/files/lib/acp/page/VersionTrackerListPage.class.php
index 7cae4b06d60..376dc3f394f 100644
--- a/wcfsetup/install/files/lib/acp/page/VersionTrackerListPage.class.php
+++ b/wcfsetup/install/files/lib/acp/page/VersionTrackerListPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\acp\page;
 
+use wcf\data\DatabaseObject;
 use wcf\data\IVersionTrackerObject;
 use wcf\data\language\Language;
 use wcf\page\AbstractPage;
@@ -39,7 +40,7 @@ class VersionTrackerListPage extends AbstractPage
     public $objectType = '';
 
     /**
-     * @var IVersionTrackerProvider
+     * @var IVersionTrackerProvider<DatabaseObject>
      */
     public $objectTypeProcessor;
 
@@ -74,7 +75,7 @@ class VersionTrackerListPage extends AbstractPage
 
     /**
      * differences between both versions
-     * @var array
+     * @var mixed[]
      */
     public $diffs = [];
 
diff --git a/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php b/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
index a2fabe34967..eb62ecb3a48 100644
--- a/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
@@ -92,7 +92,8 @@ public function execute()
     /**
      * Sends a JSON-encoded response.
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return never
      */
     protected function sendJsonResponse(array $data)
     {
diff --git a/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php b/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
index e8a4185cc22..41abe4c9f05 100644
--- a/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
@@ -148,7 +148,8 @@ public function execute()
     /**
      * Sends a JSON-encoded response.
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return void
      */
     protected function sendJsonResponse(array $data)
     {
diff --git a/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php b/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
index 242940e4c8c..ea065c757c4 100644
--- a/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
@@ -121,6 +121,8 @@ public function execute()
 
     /**
      * Invokes action method.
+     *
+     * @return void
      */
     protected function invoke()
     {
@@ -160,6 +162,8 @@ protected function invoke()
 
     /**
      * Sends JSON-Encoded response.
+     *
+     * @return mixed
      */
     protected function sendResponse()
     {
@@ -181,6 +185,8 @@ public function getResponse()
 
     /**
      * Enables debug mode.
+     *
+     * @return void
      */
     public function enableDebugMode()
     {
@@ -203,7 +209,7 @@ public function enableDebugMode()
      *  )
      * )
      *
-     * @param array $data
+     * @param array<string, mixed> $data
      * @return  AJAXInvokeAction
      * @throws  SystemException
      */
diff --git a/wcfsetup/install/files/lib/action/AJAXUploadAction.class.php b/wcfsetup/install/files/lib/action/AJAXUploadAction.class.php
index 2a4a8bc6b57..e0e2d18c61a 100644
--- a/wcfsetup/install/files/lib/action/AJAXUploadAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXUploadAction.class.php
@@ -4,7 +4,6 @@
 
 use Laminas\Diactoros\Response\JsonResponse;
 use wcf\system\upload\UploadHandler;
-use wcf\util\JSON;
 
 /**
  * Default implementation for file uploads using the AJAX-API.
@@ -26,7 +25,7 @@ public function readParameters()
     }
 
     /**
-     * @inheritDoc
+     * @return mixed
      */
     protected function sendResponse()
     {
diff --git a/wcfsetup/install/files/lib/action/AbstractAction.class.php b/wcfsetup/install/files/lib/action/AbstractAction.class.php
index 51ac1305553..e43f1fadf76 100644
--- a/wcfsetup/install/files/lib/action/AbstractAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractAction.class.php
@@ -39,9 +39,7 @@ abstract class AbstractAction implements IAction
     /**
      * @inheritDoc
      */
-    final public function __construct()
-    {
-    }
+    final public function __construct() {}
 
     /**
      * @inheritDoc
@@ -121,6 +119,8 @@ public function execute()
     /**
      * Calls the 'executed' event after the successful execution of this action.
      * This functions won't called automatically. You must do this manually, if you inherit AbstractAction.
+     *
+     * @return void
      */
     protected function executed()
     {
diff --git a/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php b/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
index be5ecac70bf..4452a35525a 100644
--- a/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
@@ -12,7 +12,8 @@ abstract class AbstractAjaxAction extends AbstractAction
     /**
      * Sends a JSON-encoded response.
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return never
      */
     protected function sendJsonResponse(array $data)
     {
diff --git a/wcfsetup/install/files/lib/action/AbstractDialogAction.class.php b/wcfsetup/install/files/lib/action/AbstractDialogAction.class.php
index dc985bdde1a..0cc02bd85bd 100644
--- a/wcfsetup/install/files/lib/action/AbstractDialogAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractDialogAction.class.php
@@ -3,6 +3,7 @@
 namespace wcf\action;
 
 use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
 use wcf\system\exception\AJAXException;
 use wcf\system\exception\IllegalLinkException;
 use wcf\util\StringUtil;
@@ -26,7 +27,7 @@ abstract class AbstractDialogAction extends AbstractSecureAction
 
     /**
      * response data
-     * @var array
+     * @var mixed[]
      */
     public $data = [];
 
@@ -54,7 +55,7 @@ public function readParameters()
     /**
      * @inheritDoc
      */
-    final public function execute()
+    final public function execute(): ResponseInterface
     {
         parent::execute();
 
@@ -73,6 +74,8 @@ final public function execute()
 
     /**
      * Validates current dialog step.
+     *
+     * @return void
      */
     abstract protected function validateStep();
 }
diff --git a/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php b/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
index 57e04b01e12..c06351cf95e 100644
--- a/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
@@ -108,6 +108,8 @@ protected function usePkce(): bool
 
     /**
      * Turns the access token response into an oauth user.
+     *
+     * @param array<string, string> $accessToken
      */
     abstract protected function getUser(array $accessToken): OauthUser;
 
@@ -118,6 +120,8 @@ abstract protected function processUser(OauthUser $oauthUser): ResponseInterface
 
     /**
      * Validates the state parameter.
+     *
+     * @return void
      */
     protected function validateState()
     {
@@ -138,6 +142,8 @@ protected function validateState()
 
     /**
      * Turns the 'code' into an access token.
+     *
+     * @return mixed[]
      */
     protected function codeToAccessToken(string $code): array
     {
diff --git a/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php b/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
index 91c9e7cf267..4cfb45c29fe 100644
--- a/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
@@ -124,6 +124,8 @@ protected function mapParameters(ServerRequestInterface $request): OAuth2Success
 
     /**
      * Turns the 'code' into an access token.
+     *
+     * @return mixed[]
      */
     protected function getAccessToken(OAuth2Success $auth2Success): array
     {
@@ -247,6 +249,8 @@ protected function validateState(OAuth2Success $auth2Success): void
 
     /**
      * Turns the access token response into an oauth user.
+     *
+     * @param mixed[] $accessToken
      */
     abstract protected function getUser(array $accessToken): OauthUser;
 
diff --git a/wcfsetup/install/files/lib/action/AbstractSecureAction.class.php b/wcfsetup/install/files/lib/action/AbstractSecureAction.class.php
index 7f350ed4867..938339c9855 100644
--- a/wcfsetup/install/files/lib/action/AbstractSecureAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractSecureAction.class.php
@@ -27,6 +27,8 @@ public function readParameters()
 
     /**
      * Validates the security token.
+     *
+     * @return void
      */
     protected function checkSecurityToken()
     {
diff --git a/wcfsetup/install/files/lib/action/BackgroundQueuePerformAction.class.php b/wcfsetup/install/files/lib/action/BackgroundQueuePerformAction.class.php
index 5754508f600..078d94f4c37 100644
--- a/wcfsetup/install/files/lib/action/BackgroundQueuePerformAction.class.php
+++ b/wcfsetup/install/files/lib/action/BackgroundQueuePerformAction.class.php
@@ -24,7 +24,7 @@ final class BackgroundQueuePerformAction extends AbstractAction
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): JsonResponse
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/action/CoreRewriteTestAction.class.php b/wcfsetup/install/files/lib/action/CoreRewriteTestAction.class.php
index cabcd15279a..1a7935b0992 100644
--- a/wcfsetup/install/files/lib/action/CoreRewriteTestAction.class.php
+++ b/wcfsetup/install/files/lib/action/CoreRewriteTestAction.class.php
@@ -3,6 +3,7 @@
 namespace wcf\action;
 
 use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
 use wcf\util\HeaderUtil;
 
 /**
@@ -20,7 +21,7 @@ final class CoreRewriteTestAction extends AbstractAction
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): ResponseInterface
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/action/CronjobPerformAction.class.php b/wcfsetup/install/files/lib/action/CronjobPerformAction.class.php
index a663813097c..058df950ded 100644
--- a/wcfsetup/install/files/lib/action/CronjobPerformAction.class.php
+++ b/wcfsetup/install/files/lib/action/CronjobPerformAction.class.php
@@ -3,7 +3,6 @@
 namespace wcf\action;
 
 use Laminas\Diactoros\Response\EmptyResponse;
-use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\RequestHandlerInterface;
 use wcf\system\cronjob\CronjobScheduler;
@@ -19,7 +18,7 @@
  */
 final class CronjobPerformAction implements RequestHandlerInterface
 {
-    public function handle(ServerRequestInterface $request): ResponseInterface
+    public function handle(ServerRequestInterface $request): EmptyResponse
     {
         CronjobScheduler::getInstance()->executeCronjobs();
 
diff --git a/wcfsetup/install/files/lib/action/FileDownloadAction.class.php b/wcfsetup/install/files/lib/action/FileDownloadAction.class.php
index 52418b0f2bc..2d8696f40c0 100644
--- a/wcfsetup/install/files/lib/action/FileDownloadAction.class.php
+++ b/wcfsetup/install/files/lib/action/FileDownloadAction.class.php
@@ -159,6 +159,9 @@ public function handle(ServerRequestInterface $request): ResponseInterface
             ->withHeader('etag', $eTag);
     }
 
+    /**
+     * @return array{0: ?int, 1: ?int}
+     */
     private function parseRangeHeader(ServerRequestInterface $request, int $fileSize): array
     {
         $startByte = 0;
diff --git a/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php b/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
index ba8bd180dd0..e2b8de754d3 100644
--- a/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
@@ -19,10 +19,15 @@ final class GoogleAuthAction extends AbstractOauth2AuthAction
 {
     const AVAILABLE_DURING_OFFLINE_MODE = true;
 
+    /**
+     * @var mixed[]
+     */
     private array $configuration;
 
     /**
      * Returns Google's OpenID Connect configuration.
+     *
+     * @return mixed[]
      */
     private function getConfiguration(): array
     {
diff --git a/wcfsetup/install/files/lib/action/GridViewFilterAction.class.php b/wcfsetup/install/files/lib/action/GridViewFilterAction.class.php
index 6140fee218f..e93d00a2cde 100644
--- a/wcfsetup/install/files/lib/action/GridViewFilterAction.class.php
+++ b/wcfsetup/install/files/lib/action/GridViewFilterAction.class.php
@@ -6,6 +6,8 @@
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\RequestHandlerInterface;
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\http\Helper;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\exception\PermissionDeniedException;
@@ -42,7 +44,7 @@ public function handle(ServerRequestInterface $request): ResponseInterface
             throw new UserInputException('gridView', 'invalid');
         }
 
-        /** @var AbstractGridView $view */
+        /** @var AbstractGridView<DatabaseObject, DatabaseObjectList<DatabaseObject>> $view */
         $view = new $parameters['gridView'](...$parameters['gridViewParameters']);
 
         if (!$view->isAccessible()) {
@@ -78,6 +80,10 @@ public function handle(ServerRequestInterface $request): ResponseInterface
         }
     }
 
+    /**
+     * @param AbstractGridView<DatabaseObject, DatabaseObjectList<DatabaseObject>> $gridView
+     * @param array<string, mixed> $values
+     */
     private function getForm(AbstractGridView $gridView, array $values): Psr15DialogForm
     {
         $form = new Psr15DialogForm(
diff --git a/wcfsetup/install/files/lib/action/IAction.class.php b/wcfsetup/install/files/lib/action/IAction.class.php
index a1023e4c0df..42b839731be 100644
--- a/wcfsetup/install/files/lib/action/IAction.class.php
+++ b/wcfsetup/install/files/lib/action/IAction.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\action;
 
+use Psr\Http\Message\ResponseInterface;
+
 /**
  * All action classes should implement this interface.
  * An action executes a user input without showing a result page or a form.
@@ -14,26 +16,36 @@ interface IAction
 {
     /**
      * Initializes this action.
+     *
+     * @return void|ResponseInterface
      */
     public function __run();
 
     /**
      * Reads the given parameters.
+     *
+     * @return void|ResponseInterface
      */
     public function readParameters();
 
     /**
      * Checks the modules of this action.
+     *
+     * @return void
      */
     public function checkModules();
 
     /**
      * Checks the permissions of this action.
+     *
+     * @return void
      */
     public function checkPermissions();
 
     /**
      * Executes this action.
+     *
+     * @return void|ResponseInterface
      */
     public function execute();
 }
diff --git a/wcfsetup/install/files/lib/action/ImageProxyAction.class.php b/wcfsetup/install/files/lib/action/ImageProxyAction.class.php
index 0664460ddc9..8f86868f537 100644
--- a/wcfsetup/install/files/lib/action/ImageProxyAction.class.php
+++ b/wcfsetup/install/files/lib/action/ImageProxyAction.class.php
@@ -78,7 +78,7 @@ private function getHttpClient(): ClientInterface
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): RedirectResponse
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/action/NotificationConfirmAction.class.php b/wcfsetup/install/files/lib/action/NotificationConfirmAction.class.php
index 34758c5de61..648fee18249 100644
--- a/wcfsetup/install/files/lib/action/NotificationConfirmAction.class.php
+++ b/wcfsetup/install/files/lib/action/NotificationConfirmAction.class.php
@@ -64,7 +64,7 @@ public function readParameters()
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): RedirectResponse
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/action/NotificationDisableAction.class.php b/wcfsetup/install/files/lib/action/NotificationDisableAction.class.php
index ed84618ed22..438ef55bb95 100644
--- a/wcfsetup/install/files/lib/action/NotificationDisableAction.class.php
+++ b/wcfsetup/install/files/lib/action/NotificationDisableAction.class.php
@@ -38,7 +38,7 @@ final class NotificationDisableAction extends AbstractAction
     /**
      * @inheritDoc
      */
-    public function readParameters()
+    public function readParameters(): RedirectResponse
     {
         parent::readParameters();
 
diff --git a/wcfsetup/install/files/lib/action/PaypalCallbackAction.class.php b/wcfsetup/install/files/lib/action/PaypalCallbackAction.class.php
index f2a6c44cf4b..7adf6d39dde 100644
--- a/wcfsetup/install/files/lib/action/PaypalCallbackAction.class.php
+++ b/wcfsetup/install/files/lib/action/PaypalCallbackAction.class.php
@@ -5,6 +5,7 @@
 use GuzzleHttp\Psr7\Request;
 use Laminas\Diactoros\Response\EmptyResponse;
 use Psr\Http\Client\ClientExceptionInterface;
+use Psr\Http\Message\ResponseInterface;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\io\HttpFactory;
 use wcf\system\payment\type\IPaymentType;
@@ -22,7 +23,7 @@ final class PaypalCallbackAction extends AbstractAction
     /**
      * @inheritDoc
      */
-    public function execute()
+    public function execute(): ResponseInterface
     {
         parent::execute();
 
diff --git a/wcfsetup/install/files/lib/action/TAJAXException.class.php b/wcfsetup/install/files/lib/action/TAJAXException.class.php
index beccd550445..f6ede078722 100644
--- a/wcfsetup/install/files/lib/action/TAJAXException.class.php
+++ b/wcfsetup/install/files/lib/action/TAJAXException.class.php
@@ -27,9 +27,10 @@ trait TAJAXException
      * Throws an previously caught exception while maintaining the propriate stacktrace.
      *
      * @param \Exception|\Throwable $e
-     * @throws  AJAXException
-     * @throws  \Exception
-     * @throws  \Throwable
+     * @return never
+     * @throws AJAXException
+     * @throws \Exception
+     * @throws \Throwable
      */
     protected function throwException($e)
     {
diff --git a/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php b/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
index de9d676fcfa..7b6287e1dce 100644
--- a/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
@@ -202,6 +202,8 @@ protected function getAccessToken(OAuth2Success $auth2Success): array
 
     /**
      * Requests an request_token to initiate the OAuth flow.
+     *
+     * @return mixed[]
      */
     private function getRequestToken(): array
     {
@@ -264,7 +266,7 @@ protected function initiate(): ResponseInterface
     /**
      * Builds the OAuth authorization header.
      *
-     * @param array $parameters
+     * @param array<string, string|int> $parameters
      */
     public function buildOAuthHeader(array $parameters): string
     {
@@ -285,6 +287,8 @@ public function buildOAuthHeader(array $parameters): string
 
     /**
      * Creates an OAuth 1 signature.
+     *
+     * @param array<string, string|int> $parameters
      */
     public function createSignature(
         string $url,
diff --git a/wcfsetup/install/files/lib/core.functions.php b/wcfsetup/install/files/lib/core.functions.php
index b41e5d209a5..2f2ba6116e2 100644
--- a/wcfsetup/install/files/lib/core.functions.php
+++ b/wcfsetup/install/files/lib/core.functions.php
@@ -22,6 +22,8 @@
 	/**
 	 * Helper method to output debug data for all passed variables,
 	 * uses `print_r()` for arrays and objects, `var_dump()` otherwise.
+	 *
+	 * @return never
 	 */
 	function wcfDebug()
 	{
@@ -108,6 +110,8 @@ class SensitiveArgument {}
 	/**
 	 * If the stacktrace contains a compiled template, the context of the relevant template line
 	 * is returned, otherwise an empty array is returned.
+	 *
+	 * @return string[]
 	 */
 	function getTemplateContextLines(\Throwable $e): array
 	{
@@ -251,7 +255,8 @@ function logThrowable(\Throwable $e, &$logFile = null): string
 	 * Pretty prints the given Throwable. It is recommended to `exit;`
 	 * the request after calling this function.
 	 *
-	 * @throws	\Exception
+	 * @return void
+	 * @throws \Exception
 	 */
 	function printThrowable(\Throwable $e)
 	{
@@ -902,6 +907,8 @@ function sanitizeStacktrace(\Throwable $e, bool $ignorePaths = false)
 	 * This has the downside that the middleware is less transparent but they simply
 	 * rendered stack traces, especially those pasted into messages, unreadable.
 	 * In particular wrapped exceptions could yield massive stack traces.
+	 *
+	 * @return mixed[]
 	 */
 	function getTraceWithoutIntermediateMiddleware(\Throwable $e): array
 	{
@@ -959,6 +966,9 @@ function formatPath(string $path, int $lineNumber): string
 		);
 	}
 
+	/**
+	 * @param mixed[] $segment
+	 */
 	function isMiddlewareStart(array $segment): bool
 	{
 		if (!isset($segment['class'])) {
@@ -968,6 +978,9 @@ function isMiddlewareStart(array $segment): bool
 		return $segment['class'] === Pipeline::class && $segment['function'] === 'process';
 	}
 
+	/**
+	 * @param mixed[] $segment
+	 */
 	function isMiddlewareEnd(array $segment): bool
 	{
 		if (!isset($segment['class'])) {
diff --git a/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php b/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
index ff45dafdfa4..723550d8e51 100644
--- a/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
@@ -18,6 +18,9 @@
  * @author  Alexander Ebert
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @template TDatabaseObjectEditor of DatabaseObjectEditor<TDatabaseObject>
  */
 abstract class AbstractDatabaseObjectAction implements IDatabaseObjectAction, IDeleteAction
 {
@@ -41,13 +44,13 @@ abstract class AbstractDatabaseObjectAction implements IDatabaseObjectAction, ID
 
     /**
      * list of object editors
-     * @var DatabaseObjectEditor[]
+     * @var TDatabaseObjectEditor[]
      */
     protected $objects = [];
 
     /**
      * multi-dimensional array of parameters required by an action
-     * @var array
+     * @var mixed[]
      */
     protected $parameters = [];
 
@@ -83,7 +86,7 @@ abstract class AbstractDatabaseObjectAction implements IDatabaseObjectAction, ID
 
     /**
      * values returned by executed action
-     * @var mixed
+     * @var mixed|mixed[]
      */
     protected $returnValues;
 
@@ -111,8 +114,8 @@ abstract class AbstractDatabaseObjectAction implements IDatabaseObjectAction, ID
      *
      * @param mixed[] $objects
      * @param string $action
-     * @param array $parameters
-     * @throws  SystemException
+     * @param mixed[] $parameters
+     * @throws SystemException
      */
     public function __construct(array $objects, $action, array $parameters = [])
     {
@@ -161,6 +164,7 @@ public function __construct(array $objects, $action, array $parameters = [])
      *
      * @param string $baseClass
      * @param string $indexName
+     * @return void
      */
     protected function __init($baseClass, $indexName)
     {
@@ -227,6 +231,8 @@ public function executeAction()
 
     /**
      * Resets cache of database object.
+     *
+     * @return void
      */
     protected function resetCache()
     {
@@ -254,7 +260,8 @@ public function getObjectIDs()
     /**
      * Sets the database objects.
      *
-     * @param DatabaseObjectEditor[] $objects
+     * @param TDatabaseObjectEditor[] $objects
+     * @return void
      */
     public function setObjects(array $objects)
     {
@@ -289,6 +296,8 @@ public function getReturnValues()
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateCreate()
     {
@@ -324,6 +333,8 @@ public function validateDelete()
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateUpdate()
     {
@@ -347,7 +358,7 @@ public function validateUpdate()
     /**
      * Creates new database object.
      *
-     * @return  DatabaseObject
+     * @return TDatabaseObject
      */
     public function create()
     {
@@ -375,6 +386,8 @@ public function delete()
 
     /**
      * Updates data.
+     *
+     * @return void
      */
     public function update()
     {
@@ -397,6 +410,8 @@ public function update()
 
     /**
      * Reads data by data id.
+     *
+     * @return void
      */
     protected function readObjects()
     {
@@ -417,6 +432,7 @@ protected function readObjects()
                 WHERE   " . $indexName . " IN (" . \str_repeat('?,', \count($this->objectIDs) - 1) . "?)";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute($this->objectIDs);
+        // @phpstan-ignore argument.templateType
         while ($object = $statement->fetchObject($baseClass)) {
             $this->objects[] = new $this->className($object);
         }
@@ -425,8 +441,8 @@ protected function readObjects()
     /**
      * Returns a single object and throws a UserInputException if no or more than one object is given.
      *
-     * @return  DatabaseObjectEditor
-     * @throws  UserInputException
+     * @return TDatabaseObjectEditor
+     * @throws UserInputException
      */
     protected function getSingleObject()
     {
@@ -449,6 +465,7 @@ protected function getSingleObject()
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
+     * @return void
      */
     protected function readInteger($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -461,7 +478,8 @@ protected function readInteger($variableName, $allowEmpty = false, $arrayIndex =
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
-     * @since   3.0
+     * @return void
+     * @since 3.0
      */
     protected function readIntegerArray($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -474,6 +492,7 @@ protected function readIntegerArray($variableName, $allowEmpty = false, $arrayIn
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
+     * @return void
      */
     protected function readString($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -486,7 +505,8 @@ protected function readString($variableName, $allowEmpty = false, $arrayIndex =
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
-     * @since   3.0
+     * @return void
+     * @since 3.0
      */
     protected function readStringArray($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -499,6 +519,7 @@ protected function readStringArray($variableName, $allowEmpty = false, $arrayInd
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
+     * @return void
      */
     protected function readBoolean($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -511,6 +532,7 @@ protected function readBoolean($variableName, $allowEmpty = false, $arrayIndex =
      * @param string $variableName
      * @param bool $allowEmpty
      * @param string $arrayIndex
+     * @return void
      */
     protected function readJSON($variableName, $allowEmpty = false, $arrayIndex = '')
     {
@@ -527,8 +549,9 @@ protected function readJSON($variableName, $allowEmpty = false, $arrayIndex = ''
      * @param string $arrayIndex
      * @param int $type
      * @param int $structure
-     * @throws  SystemException
-     * @throws  UserInputException
+     * @return void
+     * @throws SystemException
+     * @throws UserInputException
      */
     protected function readValue($variableName, $allowEmpty, $arrayIndex, $type, $structure)
     {
@@ -648,7 +671,7 @@ protected function readValue($variableName, $allowEmpty, $arrayIndex, $type, $st
     /**
      * Returns object class name.
      *
-     * @return  string
+     * @return string
      */
     public function getClassName()
     {
@@ -658,7 +681,7 @@ public function getClassName()
     /**
      * Returns a list of currently loaded objects.
      *
-     * @return  DatabaseObjectEditor[]
+     * @return TDatabaseObjectEditor[]
      */
     public function getObjects()
     {
diff --git a/wcfsetup/install/files/lib/data/DatabaseObject.class.php b/wcfsetup/install/files/lib/data/DatabaseObject.class.php
index d680ab781bf..5bc2f040989 100644
--- a/wcfsetup/install/files/lib/data/DatabaseObject.class.php
+++ b/wcfsetup/install/files/lib/data/DatabaseObject.class.php
@@ -45,16 +45,16 @@ abstract class DatabaseObject implements IIDObject, IStorableObject
 
     /**
      * object data
-     * @var array
+     * @var mixed[]
      */
     protected $data;
 
     /**
      * Creates a new instance of the DatabaseObject class.
      *
-     * @param mixed $id
-     * @param array $row
-     * @param DatabaseObject $object
+     * @param string|int|null $id
+     * @param mixed[]|null $row
+     * @param ?static $object
      */
     public function __construct($id, ?array $row = null, ?self $object = null)
     {
@@ -80,7 +80,8 @@ public function __construct($id, ?array $row = null, ?self $object = null)
     /**
      * Stores the data of a database row.
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return void
      */
     protected function handleData($data)
     {
@@ -222,6 +223,7 @@ public static function getDatabaseTableIndexName()
      * @param mixed $sortBy
      * @param string $sortOrder
      * @param bool $maintainIndexAssociation
+     * @return void
      */
     public static function sort(&$objects, $sortBy, $sortOrder = 'ASC', $maintainIndexAssociation = true)
     {
diff --git a/wcfsetup/install/files/lib/data/DatabaseObjectDecorator.class.php b/wcfsetup/install/files/lib/data/DatabaseObjectDecorator.class.php
index d5c1eb64f65..e7a4e4bd832 100644
--- a/wcfsetup/install/files/lib/data/DatabaseObjectDecorator.class.php
+++ b/wcfsetup/install/files/lib/data/DatabaseObjectDecorator.class.php
@@ -10,6 +10,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject
  */
 abstract class DatabaseObjectDecorator extends DatabaseObject
 {
@@ -21,17 +23,13 @@ abstract class DatabaseObjectDecorator extends DatabaseObject
 
     /**
      * decorated object
-     * @var DatabaseObject
+     * @var TDatabaseObject
      */
     protected $object;
 
-    /** @noinspection PhpMissingParentConstructorInspection */
-
     /**
-     * Creates a new DatabaseObjectDecorator object.
-     *
-     * @param DatabaseObject $object
-     * @throws  SystemException
+     * @param TDatabaseObject $object
+     * @throws SystemException
      */
     public function __construct(DatabaseObject $object)
     {
@@ -82,9 +80,9 @@ public function getData()
      * Delegates inaccessible methods calls to the decorated object.
      *
      * @param string $name
-     * @param array $arguments
-     * @return  mixed
-     * @throws  SystemException
+     * @param mixed[] $arguments
+     * @return mixed
+     * @throws SystemException
      */
     public function __call($name, $arguments)
     {
@@ -130,7 +128,7 @@ public static function getDatabaseTableIndexName()
     /**
      * Returns the name of the base class.
      *
-     * @return  string
+     * @return string
      */
     public static function getBaseClass()
     {
@@ -140,7 +138,7 @@ public static function getBaseClass()
     /**
      * Returns the decorated object
      *
-     * @return  DatabaseObject
+     * @return TDatabaseObject
      */
     public function getDecoratedObject()
     {
diff --git a/wcfsetup/install/files/lib/data/DatabaseObjectEditor.class.php b/wcfsetup/install/files/lib/data/DatabaseObjectEditor.class.php
index cac3f74222b..768eb481887 100644
--- a/wcfsetup/install/files/lib/data/DatabaseObjectEditor.class.php
+++ b/wcfsetup/install/files/lib/data/DatabaseObjectEditor.class.php
@@ -12,6 +12,10 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends DatabaseObjectDecorator<TDatabaseObject>
+ * @implements IEditableObject<TDatabaseObject>
  */
 abstract class DatabaseObjectEditor extends DatabaseObjectDecorator implements IEditableObject
 {
@@ -116,9 +120,9 @@ public static function deleteAll(array $objectIDs = [])
     /**
      * Creates a new object, returns null if the row already exists.
      *
-     * @param array $parameters
-     * @return  IStorableObject|null
-     * @since       5.3
+     * @param array<string, mixed> $parameters
+     * @return ?TDatabaseObject
+     * @since 5.3
      */
     public static function createOrIgnore(array $parameters = [])
     {
@@ -136,6 +140,8 @@ public static function createOrIgnore(array $parameters = [])
 
     /**
      * Creates the object and returns the ID.
+     *
+     * @param array<string, mixed> $parameters
      */
     public static function fastCreate(array $parameters): int|string
     {
diff --git a/wcfsetup/install/files/lib/data/DatabaseObjectList.class.php b/wcfsetup/install/files/lib/data/DatabaseObjectList.class.php
index 73181ac403d..6231a84f1f5 100644
--- a/wcfsetup/install/files/lib/data/DatabaseObjectList.class.php
+++ b/wcfsetup/install/files/lib/data/DatabaseObjectList.class.php
@@ -13,6 +13,10 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template-covariant TDatabaseObject of DatabaseObject|DatabaseObjectDecorator<DatabaseObject>
+ * @implements ITraversableObject<TDatabaseObject>
+ * @phpstan-ignore generics.variance
  */
 abstract class DatabaseObjectList implements \Countable, ITraversableObject
 {
@@ -36,7 +40,8 @@ abstract class DatabaseObjectList implements \Countable, ITraversableObject
 
     /**
      * result objects
-     * @var DatabaseObject[]
+     * @var TDatabaseObject[]
+     * @phpstan-ignore generics.variance
      */
     public $objects = [];
 
@@ -106,9 +111,6 @@ abstract class DatabaseObjectList implements \Countable, ITraversableObject
      */
     protected $indexToObject = [];
 
-    /**
-     * Creates a new DatabaseObjectList object.
-     */
     public function __construct()
     {
         // set class name
@@ -141,7 +143,7 @@ public function __construct()
     /**
      * Counts the number of objects.
      *
-     * @return  int
+     * @return int
      */
     public function countObjects()
     {
@@ -157,6 +159,8 @@ public function countObjects()
 
     /**
      * Reads the object ids from database.
+     *
+     * @return void
      */
     public function readObjectIDs()
     {
@@ -173,6 +177,8 @@ public function readObjectIDs()
 
     /**
      * Reads the objects from database.
+     *
+     * @return void
      */
     public function readObjects()
     {
@@ -191,6 +197,7 @@ public function readObjects()
                             " . (!empty($this->sqlOrderBy) ? "ORDER BY " . $this->sqlOrderBy : '');
             $statement = WCF::getDB()->prepare($sql);
             $statement->execute($this->objectIDs);
+            // @phpstan-ignore argument.templateType
             $this->objects = $statement->fetchObjects(($this->objectClassName ?: $this->className));
         } else {
             $sql = "SELECT  " . (!empty($this->sqlSelects) ? $this->sqlSelects . ($this->useQualifiedShorthand ? ',' : '') : '') . "
@@ -201,6 +208,7 @@ public function readObjects()
                     " . (!empty($this->sqlOrderBy) ? "ORDER BY " . $this->sqlOrderBy : '');
             $statement = WCF::getDB()->prepare($sql, $this->sqlLimit, $this->sqlOffset);
             $statement->execute($this->getConditionBuilder()->getParameters());
+            // @phpstan-ignore argument.templateType
             $this->objects = $statement->fetchObjects(($this->objectClassName ?: $this->className));
         }
 
@@ -227,7 +235,7 @@ public function readObjects()
     /**
      * Returns the object ids of the list.
      *
-     * @return  int[]
+     * @return int[]
      */
     public function getObjectIDs()
     {
@@ -238,6 +246,7 @@ public function getObjectIDs()
      * Sets the object ids.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function setObjectIDs(array $objectIDs)
     {
@@ -247,7 +256,7 @@ public function setObjectIDs(array $objectIDs)
     /**
      * Returns the objects of the list.
      *
-     * @return  DatabaseObject[]
+     * @return TDatabaseObject[]
      */
     public function getObjects()
     {
@@ -257,7 +266,7 @@ public function getObjects()
     /**
      * Returns the condition builder object.
      *
-     * @return  PreparedStatementConditionBuilder
+     * @return PreparedStatementConditionBuilder
      */
     public function getConditionBuilder()
     {
@@ -267,8 +276,8 @@ public function getConditionBuilder()
     /**
      * Sets the condition builder dynamically.
      *
-     * @param PreparedStatementConditionBuilder $conditionBuilder
-     * @since   5.3
+     * @return void
+     * @since 5.3
      */
     public function setConditionBuilder(PreparedStatementConditionBuilder $conditionBuilder)
     {
@@ -278,7 +287,7 @@ public function setConditionBuilder(PreparedStatementConditionBuilder $condition
     /**
      * Returns the name of the database table.
      *
-     * @return  string
+     * @return string
      */
     public function getDatabaseTableName()
     {
@@ -288,7 +297,7 @@ public function getDatabaseTableName()
     /**
      * Returns the name of the database table.
      *
-     * @return  string
+     * @return string
      */
     public function getDatabaseTableIndexName()
     {
@@ -298,7 +307,7 @@ public function getDatabaseTableIndexName()
     /**
      * Returns the name of the database table alias.
      *
-     * @return  string
+     * @return string
      */
     public function getDatabaseTableAlias()
     {
@@ -401,8 +410,8 @@ public function search($objectID)
     /**
      * Returns the only object in this list or `null` if the list is empty.
      *
-     * @return  DatabaseObject|null
-     * @throws  \BadMethodCallException     if list contains more than one object
+     * @return ?TDatabaseObject
+     * @throws \BadMethodCallException     if list contains more than one object
      */
     public function getSingleObject()
     {
diff --git a/wcfsetup/install/files/lib/data/I18nDatabaseObjectList.class.php b/wcfsetup/install/files/lib/data/I18nDatabaseObjectList.class.php
index 191c2955a9c..6ade701f7fc 100644
--- a/wcfsetup/install/files/lib/data/I18nDatabaseObjectList.class.php
+++ b/wcfsetup/install/files/lib/data/I18nDatabaseObjectList.class.php
@@ -11,6 +11,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template-covariant TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 abstract class I18nDatabaseObjectList extends DatabaseObjectList
 {
@@ -29,7 +32,7 @@ abstract class I18nDatabaseObjectList extends DatabaseObjectList
 
     /**
      * @inheritDoc
-     * @param int $languageID id of the language that should be used
+     * @param ?int $languageID id of the language that should be used
      * @throws \DomainException
      */
     public function __construct($languageID = null)
diff --git a/wcfsetup/install/files/lib/data/IAttachmentMessageQuickReplyAction.class.php b/wcfsetup/install/files/lib/data/IAttachmentMessageQuickReplyAction.class.php
index 30d337d6674..6f400e70f32 100644
--- a/wcfsetup/install/files/lib/data/IAttachmentMessageQuickReplyAction.class.php
+++ b/wcfsetup/install/files/lib/data/IAttachmentMessageQuickReplyAction.class.php
@@ -2,19 +2,27 @@
 
 namespace wcf\data;
 
+use wcf\system\attachment\AttachmentHandler;
+
 /**
  * Default interface for actions implementing quick reply with attachment support.
  *
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TContainer of DatabaseObject
+ * @template TMessage of DatabaseObject
+ * @template TMessageList of DatabaseObjectList
+ * @extends IMessageQuickReplyAction<TContainer, TMessage, TMessageList>
  */
 interface IAttachmentMessageQuickReplyAction extends IMessageQuickReplyAction
 {
     /**
      * Returns an attachment handler object.
      *
-     * @param DatabaseObject $container
+     * @param TContainer $container
+     * @return AttachmentHandler
      */
     public function getAttachmentHandler(DatabaseObject $container);
 }
diff --git a/wcfsetup/install/files/lib/data/IClipboardAction.class.php b/wcfsetup/install/files/lib/data/IClipboardAction.class.php
index 6ef9c3ecadb..1334201033f 100644
--- a/wcfsetup/install/files/lib/data/IClipboardAction.class.php
+++ b/wcfsetup/install/files/lib/data/IClipboardAction.class.php
@@ -14,11 +14,15 @@ interface IClipboardAction
 {
     /**
      * Unmarks all marked objects.
+     *
+     * @return void
      */
     public function unmarkAll();
 
     /**
      * Validates the 'unmarkAll' action.
+     *
+     * @return void
      */
     public function validateUnmarkAll();
 }
diff --git a/wcfsetup/install/files/lib/data/IDatabaseObjectAction.class.php b/wcfsetup/install/files/lib/data/IDatabaseObjectAction.class.php
index f7f7d5f5494..ad77ac6dfc9 100644
--- a/wcfsetup/install/files/lib/data/IDatabaseObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/IDatabaseObjectAction.class.php
@@ -13,39 +13,47 @@ interface IDatabaseObjectAction
 {
     /**
      * Executes the previously chosen action.
+     *
+     * @return mixed|mixed[]
      */
     public function executeAction();
 
     /**
      * Validates action-related parameters.
+     *
+     * @return void
      */
     public function validateAction();
 
     /**
      * Returns active action name.
      *
-     * @return  string
+     * @return string
      */
     public function getActionName();
 
     /**
      * Returns DatabaseObject-related object ids.
      *
-     * @return  int[]
+     * @return int[]
      */
     public function getObjectIDs();
 
     /**
      * Returns action-related parameters.
      *
-     * @return  mixed[]
+     * @return mixed[]
      */
     public function getParameters();
 
     /**
      * Returns results returned by active action.
      *
-     * @return  mixed
+     * @return array{
+     *  actionName: string,
+     *  objectIDs: int[],
+     *  returnValues: mixed|mixed[]
+     * }
      */
     public function getReturnValues();
 }
diff --git a/wcfsetup/install/files/lib/data/IDatabaseObjectProcessor.class.php b/wcfsetup/install/files/lib/data/IDatabaseObjectProcessor.class.php
index 00d5f53d3b0..496b81e6060 100644
--- a/wcfsetup/install/files/lib/data/IDatabaseObjectProcessor.class.php
+++ b/wcfsetup/install/files/lib/data/IDatabaseObjectProcessor.class.php
@@ -11,18 +11,13 @@
  */
 interface IDatabaseObjectProcessor
 {
-    /**
-     * Creates a new instance of a database object processor.
-     *
-     * @param DatabaseObject $object
-     */
     public function __construct(DatabaseObject $object);
 
     /**
      * Delegates accesses to inaccessible object properties the processed object.
      *
      * @param string $name
-     * @return  mixed
+     * @return mixed
      */
     public function __get($name);
 
@@ -31,7 +26,7 @@ public function __get($name);
      * object.
      *
      * @param string $name
-     * @return  bool
+     * @return bool
      */
     public function __isset($name);
 
@@ -39,8 +34,8 @@ public function __isset($name);
      * Delegates inaccessible method calls to the processed database object.
      *
      * @param string $name
-     * @param array $arguments
-     * @return  mixed
+     * @param mixed[] $arguments
+     * @return mixed
      */
     public function __call($name, $arguments);
 }
diff --git a/wcfsetup/install/files/lib/data/IDeleteAction.class.php b/wcfsetup/install/files/lib/data/IDeleteAction.class.php
index 24fd063193d..55d36a84c62 100644
--- a/wcfsetup/install/files/lib/data/IDeleteAction.class.php
+++ b/wcfsetup/install/files/lib/data/IDeleteAction.class.php
@@ -15,12 +15,14 @@ interface IDeleteAction
     /**
      * Deletes the relevant objects and returns the number of deleted objects.
      *
-     * @return  int
+     * @return int
      */
     public function delete();
 
     /**
      * Validates the "delete" action.
+     *
+     * @return void
      */
     public function validateDelete();
 }
diff --git a/wcfsetup/install/files/lib/data/IEditableCachedObject.class.php b/wcfsetup/install/files/lib/data/IEditableCachedObject.class.php
index 98336219aed..5bd59fdce85 100644
--- a/wcfsetup/install/files/lib/data/IEditableCachedObject.class.php
+++ b/wcfsetup/install/files/lib/data/IEditableCachedObject.class.php
@@ -8,11 +8,16 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of IStorableObject
+ * @extends IEditableObject<T>
  */
 interface IEditableCachedObject extends IEditableObject
 {
     /**
      * Resets the cache of this object type.
+     *
+     * @return void
      */
     public static function resetCache();
 }
diff --git a/wcfsetup/install/files/lib/data/IEditableObject.class.php b/wcfsetup/install/files/lib/data/IEditableObject.class.php
index 5b1d32a339d..12cac74b713 100644
--- a/wcfsetup/install/files/lib/data/IEditableObject.class.php
+++ b/wcfsetup/install/files/lib/data/IEditableObject.class.php
@@ -8,33 +8,39 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of IStorableObject
  */
 interface IEditableObject extends IStorableObject
 {
     /**
      * Creates a new object.
      *
-     * @param array $parameters
-     * @return  IStorableObject
+     * @param array<string, mixed> $parameters
+     * @return T
      */
     public static function create(array $parameters = []);
 
     /**
      * Updates this object.
      *
-     * @param array $parameters
+     * @param array<string, mixed> $parameters
+     * @return void
      */
     public function update(array $parameters = []);
 
     /**
      * Updates the counters of this object.
      *
-     * @param array $counters
+     * @param array<string, int> $counters
+     * @return void
      */
     public function updateCounters(array $counters = []);
 
     /**
      * Deletes this object.
+     *
+     * @return void
      */
     public function delete();
 
@@ -42,8 +48,8 @@ public function delete();
      * Deletes all objects with the given ids and returns the number of deleted
      * objects.
      *
-     * @param array $objectIDs
-     * @return  int
+     * @param (string|int)[] $objectIDs
+     * @return int
      */
     public static function deleteAll(array $objectIDs = []);
 }
diff --git a/wcfsetup/install/files/lib/data/IExtendedMessageQuickReplyAction.class.php b/wcfsetup/install/files/lib/data/IExtendedMessageQuickReplyAction.class.php
index 8e7edb90d44..a90530472e5 100644
--- a/wcfsetup/install/files/lib/data/IExtendedMessageQuickReplyAction.class.php
+++ b/wcfsetup/install/files/lib/data/IExtendedMessageQuickReplyAction.class.php
@@ -3,6 +3,10 @@
 namespace wcf\data;
 
 /**
+ * @template TContainer of DatabaseObject
+ * @template TMessage of DatabaseObject
+ * @template TMessageList of DatabaseObjectList
+ * @extends IMessageQuickReplyAction<TContainer, TMessage, TMessageList>
  * @deprecated 5.5 The concept of starting a message in a simple editor and then migrating to an extended editor no longer exists.
  */
 interface IExtendedMessageQuickReplyAction extends IMessageQuickReplyAction
@@ -10,12 +14,14 @@ interface IExtendedMessageQuickReplyAction extends IMessageQuickReplyAction
     /**
      * Saves message and jumps to extended mode.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function jumpToExtended();
 
     /**
      * Validates parameters to jump to extended mode.
+     *
+     * @return void
      */
     public function validateJumpToExtended();
 }
diff --git a/wcfsetup/install/files/lib/data/IFile.class.php b/wcfsetup/install/files/lib/data/IFile.class.php
index 002c7033e41..62f694f782b 100644
--- a/wcfsetup/install/files/lib/data/IFile.class.php
+++ b/wcfsetup/install/files/lib/data/IFile.class.php
@@ -20,7 +20,7 @@ interface IFile extends IStorableObject
     /**
      * Returns the physical location of the file.
      *
-     * @return  string
+     * @return string
      */
     public function getLocation();
 }
diff --git a/wcfsetup/install/files/lib/data/IGroupedUserListAction.class.php b/wcfsetup/install/files/lib/data/IGroupedUserListAction.class.php
index a71aa0162b5..cca3ccc58c2 100644
--- a/wcfsetup/install/files/lib/data/IGroupedUserListAction.class.php
+++ b/wcfsetup/install/files/lib/data/IGroupedUserListAction.class.php
@@ -13,13 +13,15 @@ interface IGroupedUserListAction
 {
     /**
      * Validates parameters to return a parsed list of users.
+     *
+     * @return void
      */
     public function validateGetGroupedUserList();
 
     /**
      * Returns a parsed list of users.
      *
-     * @return  array
+     * @return array{pageCount: int, template: string}
      */
     public function getGroupedUserList();
 }
diff --git a/wcfsetup/install/files/lib/data/IIDObject.class.php b/wcfsetup/install/files/lib/data/IIDObject.class.php
index f3d9c366d0b..dd05fb97b03 100644
--- a/wcfsetup/install/files/lib/data/IIDObject.class.php
+++ b/wcfsetup/install/files/lib/data/IIDObject.class.php
@@ -15,7 +15,7 @@ interface IIDObject
     /**
      * Returns the unique id of the object.
      *
-     * @return  int
+     * @return int
      */
     public function getObjectID();
 }
diff --git a/wcfsetup/install/files/lib/data/IImageViewerAction.class.php b/wcfsetup/install/files/lib/data/IImageViewerAction.class.php
index a2e0dae79d0..9de923577e6 100644
--- a/wcfsetup/install/files/lib/data/IImageViewerAction.class.php
+++ b/wcfsetup/install/files/lib/data/IImageViewerAction.class.php
@@ -15,6 +15,8 @@ interface IImageViewerAction
 {
     /**
      * Validates parameters to load the next images.
+     *
+     * @return void
      */
     public function validateLoadNextImages();
 
@@ -64,7 +66,7 @@ public function validateLoadNextImages();
      *  [ 'items' => 123 ]
      * )
      *
-     * @return  array
+     * @return mixed[]
      */
     public function loadNextImages();
 }
diff --git a/wcfsetup/install/files/lib/data/ILoadableContainerAction.class.php b/wcfsetup/install/files/lib/data/ILoadableContainerAction.class.php
index 64373b1c664..6de9d85ab73 100644
--- a/wcfsetup/install/files/lib/data/ILoadableContainerAction.class.php
+++ b/wcfsetup/install/files/lib/data/ILoadableContainerAction.class.php
@@ -15,11 +15,15 @@ interface ILoadableContainerAction
     /**
      * Toggles the container state of the relevant objects and loads their
      * content if necessary.
+     *
+     * @return void
      */
     public function loadContainer();
 
     /**
      * Validates the 'loadContainer' action.
+     *
+     * @return void
      */
     public function validateLoadContainer();
 }
diff --git a/wcfsetup/install/files/lib/data/IMessageInlineEditorAction.class.php b/wcfsetup/install/files/lib/data/IMessageInlineEditorAction.class.php
index eda00e2634e..b26572b1842 100644
--- a/wcfsetup/install/files/lib/data/IMessageInlineEditorAction.class.php
+++ b/wcfsetup/install/files/lib/data/IMessageInlineEditorAction.class.php
@@ -14,24 +14,28 @@ interface IMessageInlineEditorAction
     /**
      * Provides WYSIWYG editor for message inline editing.
      *
-     * @return  array
+     * @return array{actionName: 'beginEdit', template: string}
      */
     public function beginEdit();
 
     /**
      * Saves changes made to a message.
      *
-     * @return  array
+     * @return array{actionName: 'save', message: string}
      */
     public function save();
 
     /**
      * Validates parameters to begin message inline editing.
+     *
+     * @return void
      */
     public function validateBeginEdit();
 
     /**
      * Validates parameters to save changes made to a message.
+     *
+     * @return void
      */
     public function validateSave();
 }
diff --git a/wcfsetup/install/files/lib/data/IMessageQuickReplyAction.class.php b/wcfsetup/install/files/lib/data/IMessageQuickReplyAction.class.php
index 804827b1d6d..e0f6a3c006b 100644
--- a/wcfsetup/install/files/lib/data/IMessageQuickReplyAction.class.php
+++ b/wcfsetup/install/files/lib/data/IMessageQuickReplyAction.class.php
@@ -10,74 +10,81 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TContainer of DatabaseObject
+ * @template TMessage of DatabaseObject
+ * @template TMessageList of DatabaseObjectList
  */
 interface IMessageQuickReplyAction
 {
     /**
      * Creates a new message object.
      *
-     * @return  DatabaseObject
+     * @return TMessage
      */
     public function create();
 
     /**
      * Returns the current html input processor or a new one if `$message` is not null.
      *
-     * @param string|null $message source message
-     * @return      HtmlInputProcessor
+     * @param ?string $message source message
+     * @return HtmlInputProcessor
      */
     public function getHtmlInputProcessor($message = null);
 
     /**
      * Returns a message list object.
      *
-     * @param DatabaseObject $container
+     * @param TContainer $container
      * @param int $lastMessageTime
-     * @return  DatabaseObjectList
+     * @return TMessageList
      */
     public function getMessageList(DatabaseObject $container, $lastMessageTime);
 
     /**
      * Returns page no for given container object.
      *
-     * @param DatabaseObject $container
-     * @return  array
+     * @param TContainer $container
+     * @return array{0: int, 1: int}
      */
     public function getPageNo(DatabaseObject $container);
 
     /**
      * Returns the redirect url.
      *
-     * @param DatabaseObject $container
-     * @param DatabaseObject $message
-     * @return  string
+     * @param TContainer $container
+     * @param TMessage $message
+     * @return string
      */
     public function getRedirectUrl(DatabaseObject $container, DatabaseObject $message);
 
     /**
      * Validates the message.
      *
-     * @param DatabaseObject $container
-     * @param HtmlInputProcessor $htmlInputProcessor
+     * @param TContainer $container
+     * @return void
      */
     public function validateMessage(DatabaseObject $container, HtmlInputProcessor $htmlInputProcessor);
 
     /**
      * Creates a new message and returns it.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function quickReply();
 
     /**
      * Validates the container object for quick reply.
      *
-     * @param DatabaseObject $container
+     * @param TContainer $container
+     * @return void
      */
     public function validateContainer(DatabaseObject $container);
 
     /**
      * Validates parameters for quick reply.
+     *
+     * @return void
      */
     public function validateQuickReply();
 }
diff --git a/wcfsetup/install/files/lib/data/IMessageQuickReplyParametersAction.class.php b/wcfsetup/install/files/lib/data/IMessageQuickReplyParametersAction.class.php
index 6e109cad7c0..4fed97d1e4d 100644
--- a/wcfsetup/install/files/lib/data/IMessageQuickReplyParametersAction.class.php
+++ b/wcfsetup/install/files/lib/data/IMessageQuickReplyParametersAction.class.php
@@ -8,6 +8,11 @@
  * @author      Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TContainer of DatabaseObject
+ * @template TMessage of DatabaseObject
+ * @template TMessageList of DatabaseObjectList
+ * @extends IMessageQuickReplyAction<TContainer, TMessage, TMessageList>
  */
 interface IMessageQuickReplyParametersAction extends IMessageQuickReplyAction
 {
diff --git a/wcfsetup/install/files/lib/data/IMessageQuoteAction.class.php b/wcfsetup/install/files/lib/data/IMessageQuoteAction.class.php
index c711053b299..7e4c37150b2 100644
--- a/wcfsetup/install/files/lib/data/IMessageQuoteAction.class.php
+++ b/wcfsetup/install/files/lib/data/IMessageQuoteAction.class.php
@@ -15,37 +15,43 @@ interface IMessageQuoteAction
 {
     /**
      * Validates parameters to return a parsed template of all associated quotes.
+     *
+     * @return void
      */
     public function validateGetRenderedQuotes();
 
     /**
      * Returns the parsed template for all associated quotes.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getRenderedQuotes();
 
     /**
      * Validates parameters to quote an entire message.
+     *
+     * @return void
      */
     public function validateSaveFullQuote();
 
     /**
      * Quotes an entire message.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function saveFullQuote();
 
     /**
      * Validates parameters to save a quote.
+     *
+     * @return void
      */
     public function validateSaveQuote();
 
     /**
      * Saves the quote message and returns the number of stored quotes.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function saveQuote();
 }
diff --git a/wcfsetup/install/files/lib/data/IObjectTreeNode.class.php b/wcfsetup/install/files/lib/data/IObjectTreeNode.class.php
index 7a08c1582eb..fba2b0eacfc 100644
--- a/wcfsetup/install/files/lib/data/IObjectTreeNode.class.php
+++ b/wcfsetup/install/files/lib/data/IObjectTreeNode.class.php
@@ -9,6 +9,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @extends \RecursiveIterator<int, static>
  */
 interface IObjectTreeNode extends \Countable, IIDObject, \RecursiveIterator
 {
@@ -16,7 +18,8 @@ interface IObjectTreeNode extends \Countable, IIDObject, \RecursiveIterator
      * Adds the given node as child node and sets the child node's parent node to this node.
      *
      * @param IObjectTreeNode $child added child node
-     * @throws  \InvalidArgumentException       if given object is no (deocrated) instance of this class
+     * @return void
+     * @throws \InvalidArgumentException if given object is no (deocrated) instance of this class
      */
     public function addChild(self $child);
 
@@ -25,36 +28,36 @@ public function addChild(self $child);
      *
      * The minimum depth is `1`.
      *
-     * @return  int
+     * @return int
      */
     public function getDepth();
 
     /**
      * Returns the number of open parent nodes.
      *
-     * @return  int
+     * @return int
      */
     public function getOpenParentNodes();
 
     /**
      * Retruns the parent node of this node.
      *
-     * @return  static      parent node
+     * @return static parent node
      */
     public function getParentNode();
 
     /**
      * Returns `true` if this node is the last sibling and `false` otherwise.
      *
-     * @return  bool
+     * @return bool
      */
     public function isLastSibling();
 
     /**
      * Sets the parent node of this node.
      *
-     * @param IObjectTreeNode $parentNode parent node
-     * @throws  \InvalidArgumentException       if given object is no (deocrated) instance of this class
+     * @return void
+     * @throws \InvalidArgumentException if given object is no (deocrated) instance of this class
      */
     public function setParentNode(self $parentNode);
 }
diff --git a/wcfsetup/install/files/lib/data/IPermissionObject.class.php b/wcfsetup/install/files/lib/data/IPermissionObject.class.php
index 533245e2a01..d714e4013c2 100644
--- a/wcfsetup/install/files/lib/data/IPermissionObject.class.php
+++ b/wcfsetup/install/files/lib/data/IPermissionObject.class.php
@@ -17,7 +17,8 @@ interface IPermissionObject
      * Checks if the active user has the given permissions for this object.
      *
      * @param string[] $permissions
-     * @throws  PermissionDeniedException   if the active user does not have at least one of the given permissions.
+     * @return void
+     * @throws PermissionDeniedException   if the active user does not have at least one of the given permissions.
      */
     public function checkPermissions(array $permissions);
 
@@ -26,7 +27,7 @@ public function checkPermissions(array $permissions);
      * and the active user.
      *
      * @param string $permission
-     * @return  mixed
+     * @return mixed
      */
     public function getPermission($permission);
 }
diff --git a/wcfsetup/install/files/lib/data/IPopoverAction.class.php b/wcfsetup/install/files/lib/data/IPopoverAction.class.php
index a8fba25457b..93dfb2f6978 100644
--- a/wcfsetup/install/files/lib/data/IPopoverAction.class.php
+++ b/wcfsetup/install/files/lib/data/IPopoverAction.class.php
@@ -14,18 +14,15 @@ interface IPopoverAction
 {
     /**
      * Validates the `getPopover` action.
+     *
+     * @return void
      */
     public function validateGetPopover();
 
     /**
      * Returns the requested popover for a specific object.
      *
-     * Return value:
-     *  [
-     *      'template' => '...'
-     *  ]
-     *
-     * @return  string[]
+     * @return array{template: string}
      */
     public function getPopover();
 }
diff --git a/wcfsetup/install/files/lib/data/IPopoverObject.class.php b/wcfsetup/install/files/lib/data/IPopoverObject.class.php
index 748d24f8830..49b2cbd95e2 100644
--- a/wcfsetup/install/files/lib/data/IPopoverObject.class.php
+++ b/wcfsetup/install/files/lib/data/IPopoverObject.class.php
@@ -18,7 +18,7 @@ interface IPopoverObject extends IIDObject, ITitledLinkObject
     /**
      * Returns the CSS class that objects of this type use for popover links.
      *
-     * @return  string
+     * @return string
      */
     public function getPopoverLinkClass();
 }
diff --git a/wcfsetup/install/files/lib/data/ISearchAction.class.php b/wcfsetup/install/files/lib/data/ISearchAction.class.php
index 030262013fb..c776e0163d4 100644
--- a/wcfsetup/install/files/lib/data/ISearchAction.class.php
+++ b/wcfsetup/install/files/lib/data/ISearchAction.class.php
@@ -21,6 +21,8 @@ public function getSearchResultList();
 
     /**
      * Validates the "getSearchResultList" action.
+     *
+     * @return void
      */
     public function validateGetSearchResultList();
 }
diff --git a/wcfsetup/install/files/lib/data/ISortableAction.class.php b/wcfsetup/install/files/lib/data/ISortableAction.class.php
index 8689072dc9f..bbdd811ba89 100644
--- a/wcfsetup/install/files/lib/data/ISortableAction.class.php
+++ b/wcfsetup/install/files/lib/data/ISortableAction.class.php
@@ -14,11 +14,15 @@ interface ISortableAction
 {
     /**
      * Validates the 'updatePosition' action.
+     *
+     * @return void
      */
     public function validateUpdatePosition();
 
     /**
      * Updates the position of given objects.
+     *
+     * @return void
      */
     public function updatePosition();
 }
diff --git a/wcfsetup/install/files/lib/data/IStorableObject.class.php b/wcfsetup/install/files/lib/data/IStorableObject.class.php
index ca6566c2117..a7fbb1f5e4f 100644
--- a/wcfsetup/install/files/lib/data/IStorableObject.class.php
+++ b/wcfsetup/install/files/lib/data/IStorableObject.class.php
@@ -16,7 +16,7 @@ interface IStorableObject
      * such data variable exists.
      *
      * @param string $name
-     * @return  mixed
+     * @return mixed
      */
     public function __get($name);
 
@@ -25,42 +25,42 @@ public function __get($name);
      * is not NULL.
      *
      * @param string $name
-     * @return  bool
+     * @return bool
      */
     public function __isset($name);
 
     /**
      * Returns the value of all object data variables.
      *
-     * @return  mixed[]
+     * @return mixed[]
      */
     public function getData();
 
     /**
      * Returns the name of the database table.
      *
-     * @return  string
+     * @return string
      */
     public static function getDatabaseTableName();
 
     /**
      * Returns the alias of the database table.
      *
-     * @return  string
+     * @return string
      */
     public static function getDatabaseTableAlias();
 
     /**
      * Returns true if database table index is an identity column.
      *
-     * @return  bool
+     * @return bool
      */
     public static function getDatabaseTableIndexIsIdentity();
 
     /**
      * Returns the name of the database table index.
      *
-     * @return  string
+     * @return string
      */
     public static function getDatabaseTableIndexName();
 }
diff --git a/wcfsetup/install/files/lib/data/IThumbnailFile.class.php b/wcfsetup/install/files/lib/data/IThumbnailFile.class.php
index 1a6b7f5a15e..e8b6e327756 100644
--- a/wcfsetup/install/files/lib/data/IThumbnailFile.class.php
+++ b/wcfsetup/install/files/lib/data/IThumbnailFile.class.php
@@ -17,7 +17,7 @@ interface IThumbnailFile extends IFile
      * Returns the link to the thumbnail file with the given size.
      *
      * @param string $size
-     * @return  string
+     * @return string
      */
     public function getThumbnailLink($size);
 
@@ -25,14 +25,18 @@ public function getThumbnailLink($size);
      * Returns the physical location of the thumbnail file with the given size.
      *
      * @param string $size
-     * @return  string
+     * @return string
      */
     public function getThumbnailLocation($size);
 
     /**
      * Returns the available thumbnail sizes.
      *
-     * @return  array
+     * @return array<string, array{
+     *  height: int,
+     *  retainDimensions: bool|int,
+     *  width: int,
+     * }>
      */
     public static function getThumbnailSizes();
 }
diff --git a/wcfsetup/install/files/lib/data/IToggleAction.class.php b/wcfsetup/install/files/lib/data/IToggleAction.class.php
index f16b0d0b434..4b988beaba5 100644
--- a/wcfsetup/install/files/lib/data/IToggleAction.class.php
+++ b/wcfsetup/install/files/lib/data/IToggleAction.class.php
@@ -14,11 +14,15 @@ interface IToggleAction
 {
     /**
      * Toggles the "isDisabled" status of the relevant objects.
+     *
+     * @return void
      */
     public function toggle();
 
     /**
      * Validates the "toggle" action.
+     *
+     * @return void
      */
     public function validateToggle();
 }
diff --git a/wcfsetup/install/files/lib/data/IToggleContainerAction.class.php b/wcfsetup/install/files/lib/data/IToggleContainerAction.class.php
index 2838dbaab82..a36028698d2 100644
--- a/wcfsetup/install/files/lib/data/IToggleContainerAction.class.php
+++ b/wcfsetup/install/files/lib/data/IToggleContainerAction.class.php
@@ -14,11 +14,15 @@ interface IToggleContainerAction
 {
     /**
      * Toggles the container state of the relevant objects.
+     *
+     * @return void
      */
     public function toggleContainer();
 
     /**
      * Validates the 'toggleContainer' action.
+     *
+     * @return void
      */
     public function validateToggleContainer();
 }
diff --git a/wcfsetup/install/files/lib/data/ITraversableObject.class.php b/wcfsetup/install/files/lib/data/ITraversableObject.class.php
index ea76e4f92a3..649ece197b1 100644
--- a/wcfsetup/install/files/lib/data/ITraversableObject.class.php
+++ b/wcfsetup/install/files/lib/data/ITraversableObject.class.php
@@ -8,6 +8,9 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator<DatabaseObject>
+ * @extends \SeekableIterator<int, TDatabaseObject>
  */
 interface ITraversableObject extends \SeekableIterator
 {
@@ -15,6 +18,7 @@ interface ITraversableObject extends \SeekableIterator
      * Sets internal iterator pointer based upon related object id.
      *
      * @param int $objectID
+     * @return void
      */
     public function seekTo($objectID);
 
@@ -23,7 +27,7 @@ public function seekTo($objectID);
      * pointer to found item. Returns `null` if object id is not found.
      *
      * @param int $objectID
-     * @return  DatabaseObject|null
+     * @return ?TDatabaseObject
      */
     public function search($objectID);
 }
diff --git a/wcfsetup/install/files/lib/data/IUploadAction.class.php b/wcfsetup/install/files/lib/data/IUploadAction.class.php
index 4c5a2bb9cd8..73011437749 100644
--- a/wcfsetup/install/files/lib/data/IUploadAction.class.php
+++ b/wcfsetup/install/files/lib/data/IUploadAction.class.php
@@ -14,13 +14,15 @@ interface IUploadAction
 {
     /**
      * Validates the 'upload' action.
+     *
+     * @return void
      */
     public function validateUpload();
 
     /**
      * Saves uploaded files and returns the data of the uploaded files.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function upload();
 }
diff --git a/wcfsetup/install/files/lib/data/IUserContent.class.php b/wcfsetup/install/files/lib/data/IUserContent.class.php
index c98a037808d..6eb387b9838 100644
--- a/wcfsetup/install/files/lib/data/IUserContent.class.php
+++ b/wcfsetup/install/files/lib/data/IUserContent.class.php
@@ -14,21 +14,21 @@ interface IUserContent extends ITitledLinkObject
     /**
      * Returns message creation timestamp.
      *
-     * @return  int
+     * @return int
      */
     public function getTime();
 
     /**
      * Returns author's user id.
      *
-     * @return  int
+     * @return int
      */
     public function getUserID();
 
     /**
      * Returns author's username.
      *
-     * @return  string
+     * @return string
      */
     public function getUsername();
 }
diff --git a/wcfsetup/install/files/lib/data/IVisitableObjectAction.class.php b/wcfsetup/install/files/lib/data/IVisitableObjectAction.class.php
index a8bd913b5bc..6318eb165ff 100644
--- a/wcfsetup/install/files/lib/data/IVisitableObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/IVisitableObjectAction.class.php
@@ -13,11 +13,15 @@ interface IVisitableObjectAction
 {
     /**
      * Marks objects as read.
+     *
+     * @return void
      */
     public function markAsRead();
 
     /**
      * Validates parameters to mark objects as read.
+     *
+     * @return void
      */
     public function validateMarkAsRead();
 }
diff --git a/wcfsetup/install/files/lib/data/TDatabaseObjectToggle.class.php b/wcfsetup/install/files/lib/data/TDatabaseObjectToggle.class.php
index e5b5f113df3..89799a873f0 100644
--- a/wcfsetup/install/files/lib/data/TDatabaseObjectToggle.class.php
+++ b/wcfsetup/install/files/lib/data/TDatabaseObjectToggle.class.php
@@ -10,12 +10,14 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @mixin   AbstractDatabaseObjectAction
+ * @mixin AbstractDatabaseObjectAction<DatabaseObject, DatabaseObjectEditor<DatabaseObject>>
  */
 trait TDatabaseObjectToggle
 {
     /**
      * Validates the "toggle" action.
+     *
+     * @return void
      */
     public function validateToggle()
     {
@@ -24,6 +26,8 @@ public function validateToggle()
 
     /**
      * Toggles the "isDisabled" status of the relevant objects.
+     *
+     * @return void
      */
     public function toggle()
     {
diff --git a/wcfsetup/install/files/lib/data/TI18nDatabaseObjectAction.class.php b/wcfsetup/install/files/lib/data/TI18nDatabaseObjectAction.class.php
index 8465a3945b7..4a07fb83e2d 100644
--- a/wcfsetup/install/files/lib/data/TI18nDatabaseObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/TI18nDatabaseObjectAction.class.php
@@ -15,7 +15,7 @@
  * @license   GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.0
  *
- * @mixin AbstractDatabaseObjectAction
+ * @mixin AbstractDatabaseObjectAction<DatabaseObject, DatabaseObjectEditor<DatabaseObject>>
  */
 trait TI18nDatabaseObjectAction
 {
@@ -38,6 +38,8 @@ protected function deleteI18nValues(): void
 
     /**
      * Deletes language items and clears the language cache.
+     *
+     * @param string[] $languageItems
      */
     private function deleteI18nItems(array $languageItems): void
     {
diff --git a/wcfsetup/install/files/lib/data/acl/option/ACLOptionAction.class.php b/wcfsetup/install/files/lib/data/acl/option/ACLOptionAction.class.php
index f64c6ebbf03..9aa431177b8 100644
--- a/wcfsetup/install/files/lib/data/acl/option/ACLOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/ACLOptionAction.class.php
@@ -12,9 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACLOption       create()
- * @method  ACLOptionEditor[]   getObjects()
- * @method  ACLOptionEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACLOption, ACLOptionEditor>
  */
 class ACLOptionAction extends AbstractDatabaseObjectAction
 {
@@ -30,6 +28,8 @@ class ACLOptionAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates parameters for ACL options.
+     *
+     * @return void
      */
     public function validateLoadAll()
     {
@@ -41,7 +41,7 @@ public function validateLoadAll()
     /**
      * Returns a set of permissions and their values if applicable.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function loadAll()
     {
diff --git a/wcfsetup/install/files/lib/data/acl/option/ACLOptionEditor.class.php b/wcfsetup/install/files/lib/data/acl/option/ACLOptionEditor.class.php
index 4d08858e388..0be2818ea4f 100644
--- a/wcfsetup/install/files/lib/data/acl/option/ACLOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/ACLOptionEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACLOption   create(array $parameters = [])
- * @method      ACLOption   getDecoratedObject()
  * @mixin       ACLOption
+ * @extends DatabaseObjectEditor<ACLOption>
  */
 class ACLOptionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acl/option/ACLOptionList.class.php b/wcfsetup/install/files/lib/data/acl/option/ACLOptionList.class.php
index 02f0526b40a..2cdc2775df6 100644
--- a/wcfsetup/install/files/lib/data/acl/option/ACLOptionList.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/ACLOptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACLOption       current()
- * @method  ACLOption[]     getObjects()
- * @method  ACLOption|null      getSingleObject()
- * @method  ACLOption|null      search($objectID)
- * @property    ACLOption[] $objects
+ * @extends DatabaseObjectList<ACLOption>
  */
 class ACLOptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategory.class.php b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategory.class.php
index f2341558c2e..ab1a0afa3e0 100644
--- a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategory.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategory.class.php
@@ -16,6 +16,4 @@
  * @property-read   int $objectTypeID       id of the `com.woltlab.wcf.acl` object type
  * @property-read   string $categoryName       name and textual identifier of the acl option category
  */
-class ACLOptionCategory extends DatabaseObject
-{
-}
+class ACLOptionCategory extends DatabaseObject {}
diff --git a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryAction.class.php b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryAction.class.php
index ddf2a7dcd6b..fccffb57323 100644
--- a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACLOptionCategory       create()
- * @method  ACLOptionCategoryEditor[]   getObjects()
- * @method  ACLOptionCategoryEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACLOptionCategory, ACLOptionCategoryEditor>
  */
 class ACLOptionCategoryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryEditor.class.php b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryEditor.class.php
index 2e5ce337797..b4a5bef3dab 100644
--- a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACLOptionCategory   create(array $parameters = [])
- * @method      ACLOptionCategory   getDecoratedObject()
  * @mixin       ACLOptionCategory
+ * @extends DatabaseObjectEditor<ACLOptionCategory>
  */
 class ACLOptionCategoryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryList.class.php b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryList.class.php
index 7ca6acd46d9..06370430e75 100644
--- a/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/acl/option/category/ACLOptionCategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACLOptionCategory       current()
- * @method  ACLOptionCategory[]     getObjects()
- * @method  ACLOptionCategory|null      getSingleObject()
- * @method  ACLOptionCategory|null      search($objectID)
- * @property    ACLOptionCategory[] $objects
+ * @extends DatabaseObjectList<ACLOptionCategory>
  */
 class ACLOptionCategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItem.class.php b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItem.class.php
index 126d627f3fa..0270c8d2a0c 100644
--- a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItem.class.php
+++ b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItem.class.php
@@ -94,6 +94,8 @@ public function getController()
 
     /**
      * Parses controller name.
+     *
+     * @return void
      */
     protected function parseController()
     {
diff --git a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemAction.class.php b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemAction.class.php
index 799a499e907..636e55df0ab 100644
--- a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPMenuItem     create()
- * @method  ACPMenuItemEditor[] getObjects()
- * @method  ACPMenuItemEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPMenuItem, ACPMenuItemEditor>
  */
 class ACPMenuItemAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemEditor.class.php b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemEditor.class.php
index c010985f993..10d83127573 100644
--- a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACPMenuItem create(array $parameters = [])
- * @method      ACPMenuItem getDecoratedObject()
  * @mixin       ACPMenuItem
+ * @extends DatabaseObjectEditor<ACPMenuItem>
+ * @implements IEditableCachedObject<ACPMenuItem>
  */
 class ACPMenuItemEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemList.class.php b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemList.class.php
index d6f96878085..de8df287c3c 100644
--- a/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/menu/item/ACPMenuItemList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPMenuItem     current()
- * @method  ACPMenuItem[]       getObjects()
- * @method  ACPMenuItem|null    getSingleObject()
- * @method  ACPMenuItem|null    search($objectID)
- * @property    ACPMenuItem[] $objects
+ * @extends DatabaseObjectList<ACPMenuItem>
  */
 class ACPMenuItemList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderAction.class.php b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderAction.class.php
index 732271fe05a..f900356fd3d 100644
--- a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderAction.class.php
@@ -13,9 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSearchProvider       create()
- * @method  ACPSearchProviderEditor[]   getObjects()
- * @method  ACPSearchProviderEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPSearchProvider, ACPSearchProviderEditor>
  */
 class ACPSearchProviderAction extends AbstractDatabaseObjectAction implements ISearchAction
 {
diff --git a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderEditor.class.php b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderEditor.class.php
index 5edf9a7b44c..b3bfc08d74e 100644
--- a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACPSearchProvider   create(array $parameters = [])
- * @method      ACPSearchProvider   getDecoratedObject()
  * @mixin       ACPSearchProvider
+ * @extends DatabaseObjectEditor<ACPSearchProvider>
  */
 class ACPSearchProviderEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderList.class.php b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderList.class.php
index 839acad3c14..e72672cb6e3 100644
--- a/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/search/provider/ACPSearchProviderList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSearchProvider       current()
- * @method  ACPSearchProvider[]     getObjects()
- * @method  ACPSearchProvider|null      getSingleObject()
- * @method  ACPSearchProvider|null      search($objectID)
- * @property    ACPSearchProvider[] $objects
+ * @extends DatabaseObjectList<ACPSearchProvider>
  */
 class ACPSearchProviderList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/ACPSession.class.php b/wcfsetup/install/files/lib/data/acp/session/ACPSession.class.php
index 3437c9c847e..7eb44a012fc 100644
--- a/wcfsetup/install/files/lib/data/acp/session/ACPSession.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/ACPSession.class.php
@@ -32,7 +32,7 @@ class ACPSession extends DatabaseObject
     /**
      * Returns true if this session type supports persistent logins.
      *
-     * @return  bool
+     * @return bool
      */
     public static function supportsPersistentLogins()
     {
diff --git a/wcfsetup/install/files/lib/data/acp/session/ACPSessionAction.class.php b/wcfsetup/install/files/lib/data/acp/session/ACPSessionAction.class.php
index 9d61df79608..b326bfcb0bd 100644
--- a/wcfsetup/install/files/lib/data/acp/session/ACPSessionAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/ACPSessionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSession      create()
- * @method  ACPSessionEditor[]  getObjects()
- * @method  ACPSessionEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPSession, ACPSessionEditor>
  * @deprecated  5.4 Distinct ACP sessions have been removed. This class is preserved due to its use in legacy sessions.
  */
 class ACPSessionAction extends AbstractDatabaseObjectAction
diff --git a/wcfsetup/install/files/lib/data/acp/session/ACPSessionEditor.class.php b/wcfsetup/install/files/lib/data/acp/session/ACPSessionEditor.class.php
index 6e33c89d3e2..0999773fd3e 100644
--- a/wcfsetup/install/files/lib/data/acp/session/ACPSessionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/ACPSessionEditor.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSession  getDecoratedObject()
- * @mixin   ACPSession
- * @deprecated  5.4 Distinct ACP sessions have been removed. This class is preserved due to its use in legacy sessions.
+ * @mixin ACPSession
+ * @extends DatabaseObjectEditor<ACPSession>
+ * @deprecated 5.4 Distinct ACP sessions have been removed. This class is preserved due to its use in legacy sessions.
  */
 class ACPSessionEditor extends DatabaseObjectEditor
 {
@@ -27,7 +27,6 @@ class ACPSessionEditor extends DatabaseObjectEditor
 
     /**
      * @inheritDoc
-     * @return  ACPSession
      */
     public static function create(array $parameters = [])
     {
@@ -35,9 +34,7 @@ public static function create(array $parameters = [])
             $parameters['userID'] = null;
         }
 
-        $object = parent::create($parameters);
-        \assert($object instanceof ACPSession);
-        return $object;
+        return parent::create($parameters);
     }
 
     /**
@@ -53,6 +50,8 @@ public function update(array $parameters = [])
     }
 
     /**
+     * @param int[] $userIDs
+     * @return void
      * @deprecated 5.4 - Sessions are managed via the SessionHandler.
      */
     public static function deleteUserSessions(array $userIDs = [])
@@ -69,6 +68,8 @@ public static function deleteUserSessions(array $userIDs = [])
     }
 
     /**
+     * @param int $timestamp
+     * @return void
      * @deprecated 5.4 - Sessions are managed via the SessionHandler.
      */
     public static function deleteExpiredSessions($timestamp)
diff --git a/wcfsetup/install/files/lib/data/acp/session/ACPSessionList.class.php b/wcfsetup/install/files/lib/data/acp/session/ACPSessionList.class.php
index 8cda74c867a..1950dae7bd6 100644
--- a/wcfsetup/install/files/lib/data/acp/session/ACPSessionList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/ACPSessionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSession      current()
- * @method  ACPSession[]        getObjects()
- * @method  ACPSession|null     getSingleObject()
- * @method  ACPSession|null     search($objectID)
- * @property    ACPSession[] $objects
+ * @extends DatabaseObjectList<ACPSession>
  * @deprecated  5.4 Distinct ACP sessions have been removed. This class is preserved due to its use in legacy sessions.
  */
 class ACPSessionList extends DatabaseObjectList
diff --git a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLog.class.php b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLog.class.php
index 8ec0e2165af..0d53db7191c 100644
--- a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLog.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLog.class.php
@@ -28,6 +28,7 @@ class ACPSessionAccessLog extends DatabaseObject
     protected static $databaseTableIndexName = 'sessionAccessLogID';
 
     /**
+     * @return true
      * @deprecated 5.5 This method is long broken.
      */
     public function hasProtectedURI()
diff --git a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogAction.class.php b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogAction.class.php
index e1a21b88bbe..1e5be7f263d 100644
--- a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSessionAccessLog     create()
- * @method  ACPSessionAccessLogEditor[] getObjects()
- * @method  ACPSessionAccessLogEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPSessionAccessLog, ACPSessionAccessLogEditor>
  */
 class ACPSessionAccessLogAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogEditor.class.php b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogEditor.class.php
index 68d5610ecc9..93091d129ec 100644
--- a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACPSessionAccessLog create(array $parameters = [])
- * @method      ACPSessionAccessLog getDecoratedObject()
  * @mixin       ACPSessionAccessLog
+ * @extends DatabaseObjectEditor<ACPSessionAccessLog>
  */
 class ACPSessionAccessLogEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogList.class.php b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogList.class.php
index 3730ac6c891..fdfa8f138b6 100644
--- a/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/access/log/ACPSessionAccessLogList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSessionAccessLog     current()
- * @method  ACPSessionAccessLog[]       getObjects()
- * @method  ACPSessionAccessLog|null    getSingleObject()
- * @method  ACPSessionAccessLog|null    search($objectID)
- * @property    ACPSessionAccessLog[] $objects
+ * @extends DatabaseObjectList<ACPSessionAccessLog>
  */
 class ACPSessionAccessLogList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLog.class.php b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLog.class.php
index 1ce711238fc..5dc9a79cf47 100644
--- a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLog.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLog.class.php
@@ -54,6 +54,7 @@ public function __construct($id, ?array $row = null, ?DatabaseObject $object = n
     }
 
     /**
+     * @return false
      * @deprecated 5.4 - This method always returns false.
      */
     public function isActive()
@@ -62,6 +63,7 @@ public function isActive()
     }
 
     /**
+     * @return false
      * @deprecated 5.4 - This method always returns false.
      */
     public function isActiveUserSession()
diff --git a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogAction.class.php b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogAction.class.php
index 947c8bb4bfb..aa3d7e4d41d 100644
--- a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSessionLog       create()
- * @method  ACPSessionLogEditor[]   getObjects()
- * @method  ACPSessionLogEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPSessionLog, ACPSessionLogEditor>
  */
 class ACPSessionLogAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogEditor.class.php b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogEditor.class.php
index 649fb8260f6..75f62d8eda1 100644
--- a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACPSessionLog   create(array $parameters = [])
- * @method      ACPSessionLog   getDecoratedObject()
  * @mixin       ACPSessionLog
+ * @extends DatabaseObjectEditor<ACPSessionLog>
  */
 class ACPSessionLogEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogList.class.php b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogList.class.php
index 29b769a88c0..5ac237705a3 100644
--- a/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/session/log/ACPSessionLogList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPSessionLog       current()
- * @method  ACPSessionLog[]     getObjects()
- * @method  ACPSessionLog|null  getSingleObject()
- * @method  ACPSessionLog|null  search($objectID)
- * @property    ACPSessionLog[] $objects
+ * @extends DatabaseObjectList<ACPSessionLog>
  */
 class ACPSessionLogList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateAction.class.php b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateAction.class.php
index a70123a47c4..c2fc066748c 100644
--- a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateAction.class.php
+++ b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPTemplate     create()
- * @method  ACPTemplateEditor[] getObjects()
- * @method  ACPTemplateEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ACPTemplate, ACPTemplateEditor>
  */
 class ACPTemplateAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateEditor.class.php b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateEditor.class.php
index ad02a244e12..9ab6baffc30 100644
--- a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateEditor.class.php
+++ b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ACPTemplate create(array $parameters = [])
- * @method      ACPTemplate getDecoratedObject()
  * @mixin       ACPTemplate
+ * @extends DatabaseObjectEditor<ACPTemplate>
  */
 class ACPTemplateEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateList.class.php b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateList.class.php
index 2728b66134a..e65fd0423b4 100644
--- a/wcfsetup/install/files/lib/data/acp/template/ACPTemplateList.class.php
+++ b/wcfsetup/install/files/lib/data/acp/template/ACPTemplateList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ACPTemplate     current()
- * @method  ACPTemplate[]       getObjects()
- * @method  ACPTemplate|null    getSingleObject()
- * @method  ACPTemplate|null    search($objectID)
- * @property    ACPTemplate[] $objects
+ * @extends DatabaseObjectList<ACPTemplate>
  */
 class ACPTemplateList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/ad/AdAction.class.php b/wcfsetup/install/files/lib/data/ad/AdAction.class.php
index 92a7c3ecc5f..bc273548244 100644
--- a/wcfsetup/install/files/lib/data/ad/AdAction.class.php
+++ b/wcfsetup/install/files/lib/data/ad/AdAction.class.php
@@ -17,9 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  AdEditor[]  getObjects()
- * @method  AdEditor    getSingleObject()
- * @property-read AdEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Ad, AdEditor>
  */
 class AdAction extends AbstractDatabaseObjectAction implements ISortableAction, IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/ad/AdEditor.class.php b/wcfsetup/install/files/lib/data/ad/AdEditor.class.php
index 1fdbccc7705..8c07c5d4ee7 100644
--- a/wcfsetup/install/files/lib/data/ad/AdEditor.class.php
+++ b/wcfsetup/install/files/lib/data/ad/AdEditor.class.php
@@ -16,9 +16,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Ad  create(array $parameters = [])
- * @method      Ad  getDecoratedObject()
  * @mixin       Ad
+ * @extends DatabaseObjectEditor<Ad>
+ * @implements IEditableCachedObject<Ad>
  */
 class AdEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -31,6 +31,7 @@ class AdEditor extends DatabaseObjectEditor implements IEditableCachedObject
      * Sets the show order of the ad.
      *
      * @param int $showOrder
+     * @return void
      */
     public function setShowOrder($showOrder = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/ad/AdList.class.php b/wcfsetup/install/files/lib/data/ad/AdList.class.php
index f3d48a1fc40..c3f81224b8f 100644
--- a/wcfsetup/install/files/lib/data/ad/AdList.class.php
+++ b/wcfsetup/install/files/lib/data/ad/AdList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Ad      current()
- * @method  Ad[]        getObjects()
- * @method  Ad|null     getSingleObject()
- * @method  Ad|null     search($objectID)
- * @property    Ad[] $objects
+ * @extends DatabaseObjectList<Ad>
  */
-class AdList extends DatabaseObjectList
-{
-}
+class AdList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/application/ApplicationAction.class.php b/wcfsetup/install/files/lib/data/application/ApplicationAction.class.php
index c91c4436180..ba2e1636105 100644
--- a/wcfsetup/install/files/lib/data/application/ApplicationAction.class.php
+++ b/wcfsetup/install/files/lib/data/application/ApplicationAction.class.php
@@ -15,9 +15,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Application     create()
- * @method  ApplicationEditor[] getObjects()
- * @method  ApplicationEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Application, ApplicationEditor>
  */
 class ApplicationAction extends AbstractDatabaseObjectAction
 {
@@ -34,6 +32,8 @@ class ApplicationAction extends AbstractDatabaseObjectAction
 
     /**
      * Assigns a list of applications to a group and computes cookie domain.
+     *
+     * @return void
      */
     public function rebuild()
     {
@@ -71,6 +71,8 @@ public function rebuild()
 
     /**
      * Marks an application as tainted, prevents loading it during uninstallation.
+     *
+     * @return void
      */
     public function markAsTainted()
     {
diff --git a/wcfsetup/install/files/lib/data/application/ApplicationEditor.class.php b/wcfsetup/install/files/lib/data/application/ApplicationEditor.class.php
index 2ab4a5d99d9..034faea2ee2 100644
--- a/wcfsetup/install/files/lib/data/application/ApplicationEditor.class.php
+++ b/wcfsetup/install/files/lib/data/application/ApplicationEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Application create(array $parameters = [])
- * @method      Application getDecoratedObject()
  * @mixin       Application
+ * @extends DatabaseObjectEditor<Application>
+ * @implements IEditableCachedObject<Application>
  */
 class ApplicationEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/application/ApplicationList.class.php b/wcfsetup/install/files/lib/data/application/ApplicationList.class.php
index 1f0f0908756..81bcea8b847 100644
--- a/wcfsetup/install/files/lib/data/application/ApplicationList.class.php
+++ b/wcfsetup/install/files/lib/data/application/ApplicationList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\application;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -11,11 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Application     current()
- * @method  Application[]       getObjects()
- * @method  Application|null    getSingleObject()
- * @method  Application|null    search($objectID)
- * @property    Application[] $objects
+ * @template TDatabaseObject of Application|DatabaseObjectDecorator<Application> = Application
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class ApplicationList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/application/ViewableApplication.class.php b/wcfsetup/install/files/lib/data/application/ViewableApplication.class.php
index 55743144a77..28e211d35a0 100644
--- a/wcfsetup/install/files/lib/data/application/ViewableApplication.class.php
+++ b/wcfsetup/install/files/lib/data/application/ViewableApplication.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Application     getDecoratedObject()
  * @mixin   Application
+ * @extends DatabaseObjectDecorator<Application>
  */
 class ViewableApplication extends DatabaseObjectDecorator
 {
diff --git a/wcfsetup/install/files/lib/data/application/ViewableApplicationList.class.php b/wcfsetup/install/files/lib/data/application/ViewableApplicationList.class.php
index 76154fc4633..04d11fd5e8a 100644
--- a/wcfsetup/install/files/lib/data/application/ViewableApplicationList.class.php
+++ b/wcfsetup/install/files/lib/data/application/ViewableApplicationList.class.php
@@ -9,11 +9,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ViewableApplication     current()
- * @method  ViewableApplication[]       getObjects()
- * @method  ViewableApplication|null    getSingleObject()
- * @method  ViewableApplication|null    search($objectID)
- * @property    ViewableApplication[] $objects
+ * @extends ApplicationList<ViewableApplication>
  */
 class ViewableApplicationList extends ApplicationList
 {
diff --git a/wcfsetup/install/files/lib/data/article/Article.class.php b/wcfsetup/install/files/lib/data/article/Article.class.php
index eb64d346bcd..47f179dbbde 100644
--- a/wcfsetup/install/files/lib/data/article/Article.class.php
+++ b/wcfsetup/install/files/lib/data/article/Article.class.php
@@ -337,7 +337,7 @@ public function getCategory()
     /**
      * Sets the discussion provider for this article.
      *
-     * @param IArticleDiscussionProvider $discussionProvider
+     * @return void
      * @since       5.2
      */
     public function setDiscussionProvider(IArticleDiscussionProvider $discussionProvider)
diff --git a/wcfsetup/install/files/lib/data/article/ArticleAction.class.php b/wcfsetup/install/files/lib/data/article/ArticleAction.class.php
index 19f019bb7c7..b8101d7291c 100644
--- a/wcfsetup/install/files/lib/data/article/ArticleAction.class.php
+++ b/wcfsetup/install/files/lib/data/article/ArticleAction.class.php
@@ -36,9 +36,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ArticleEditor[] getObjects()
- * @method  ArticleEditor   getSingleObject()
- * @property-read ArticleEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Article, ArticleEditor>
  */
 class ArticleAction extends AbstractDatabaseObjectAction
 {
@@ -86,7 +84,6 @@ class ArticleAction extends AbstractDatabaseObjectAction
 
     /**
      * @inheritDoc
-     * @return  Article
      */
     public function create()
     {
@@ -94,7 +91,6 @@ public function create()
             $this->parameters['data']['attachments'] = \count($this->parameters['attachmentHandler']);
         }
 
-        /** @var Article $article */
         $article = parent::create();
 
         // save article content
@@ -381,6 +377,7 @@ public function update()
     /**
      * Validates parameters to delete articles.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      */
@@ -479,6 +476,8 @@ public function delete()
     /**
      * Validates parameters to move articles to the trash bin.
      *
+     *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      */
@@ -505,6 +504,8 @@ public function validateTrash()
 
     /**
      * Moves articles to the trash bin.
+     *
+     * @return array{objectIDs: int[]}
      */
     public function trash()
     {
@@ -525,6 +526,7 @@ public function trash()
     /**
      * Validates parameters to restore articles.
      *
+     * @return void
      * @throws  UserInputException
      */
     public function validateRestore()
@@ -534,6 +536,8 @@ public function validateRestore()
 
     /**
      * Restores articles.
+     *
+     * @return array{objectIDs: int[]}
      */
     public function restore()
     {
@@ -554,6 +558,7 @@ public function restore()
     /**
      * Validates parameters to toggle between i18n and monolingual mode.
      *
+     * @return void
      * @throws      UserInputException
      */
     public function validateToggleI18n()
@@ -578,6 +583,8 @@ public function validateToggleI18n()
 
     /**
      * Toggles between i18n and monolingual mode.
+     *
+     * @return void
      */
     public function toggleI18n()
     {
@@ -632,6 +639,8 @@ public function toggleI18n()
 
     /**
      * Marks articles as read.
+     *
+     * @return void
      */
     public function markAsRead()
     {
@@ -673,6 +682,8 @@ public function markAsRead()
 
     /**
      * Marks all articles as read.
+     *
+     * @return void
      */
     public function markAllAsRead()
     {
@@ -688,6 +699,8 @@ public function markAllAsRead()
 
     /**
      * Validates the mark all as read action.
+     *
+     * @return void
      */
     public function validateMarkAllAsRead()
     {
@@ -697,6 +710,7 @@ public function validateMarkAllAsRead()
     /**
      * Validates the `setCategory` action.
      *
+     * @return void
      * @throws  UserInputException
      */
     public function validateSetCategory()
@@ -730,6 +744,8 @@ public function validateSetCategory()
 
     /**
      * Sets the category of articles.
+     *
+     * @return void
      */
     public function setCategory()
     {
@@ -743,6 +759,7 @@ public function setCategory()
     /**
      * Validates the `publish` action.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      */
@@ -769,6 +786,8 @@ public function validatePublish()
 
     /**
      * Publishes articles.
+     *
+     * @return void
      */
     public function publish()
     {
@@ -816,6 +835,7 @@ public function publish()
     /**
      * Validates the `unpublish` action.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      */
@@ -842,6 +862,8 @@ public function validateUnpublish()
 
     /**
      * Unpublishes articles.
+     *
+     * @return void
      */
     public function unpublish()
     {
@@ -877,6 +899,8 @@ public function unpublish()
 
     /**
      * Validates parameters to search for an article by its localized title.
+     *
+     * @return void
      */
     public function validateSearch()
     {
@@ -886,7 +910,11 @@ public function validateSearch()
     /**
      * Searches for an article by its localized title.
      *
-     * @return      array   list of matching articles
+     * @return list<array{
+     *  displayLink: string,
+     *  name: string,
+     *  articleID: int,
+     * }> list of matching articles
      */
     public function search()
     {
@@ -929,6 +957,7 @@ public function search()
      * Unmarks articles.
      *
      * @param int[] $articleIDs
+     * @return void
      */
     protected function unmarkItems(array $articleIDs = [])
     {
diff --git a/wcfsetup/install/files/lib/data/article/ArticleEditor.class.php b/wcfsetup/install/files/lib/data/article/ArticleEditor.class.php
index 1dd11f4b382..8a08971b9d0 100644
--- a/wcfsetup/install/files/lib/data/article/ArticleEditor.class.php
+++ b/wcfsetup/install/files/lib/data/article/ArticleEditor.class.php
@@ -13,9 +13,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static Article     create(array $parameters = [])
- * @method      Article     getDecoratedObject()
  * @mixin       Article
+ * @extends DatabaseObjectEditor<Article>
  */
 class ArticleEditor extends DatabaseObjectEditor
 {
@@ -27,8 +26,9 @@ class ArticleEditor extends DatabaseObjectEditor
     /**
      * Updates the article counter of the given user ids.
      *
-     * @param int[] $users user id => article counter increase/decrease
-     * @since       5.2
+     * @param array<int, int> $users user id => article counter increase/decrease
+     * @return void
+     * @since 5.2
      */
     public static function updateArticleCounter(array $users)
     {
diff --git a/wcfsetup/install/files/lib/data/article/ArticleList.class.php b/wcfsetup/install/files/lib/data/article/ArticleList.class.php
index b3890e67538..88de4e9dcb8 100644
--- a/wcfsetup/install/files/lib/data/article/ArticleList.class.php
+++ b/wcfsetup/install/files/lib/data/article/ArticleList.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\data\article;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -12,11 +14,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Article     current()
- * @method  Article[]       getObjects()
- * @method  Article|null    getSingleObject()
- * @method  Article|null    search($objectID)
- * @property    Article[] $objects
+ * @template-covariant TDatabaseObject of Article|DatabaseObjectDecorator = Article
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class ArticleList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/article/ArticleVersionTracker.class.php b/wcfsetup/install/files/lib/data/article/ArticleVersionTracker.class.php
index 090f7c55202..33af55af36b 100644
--- a/wcfsetup/install/files/lib/data/article/ArticleVersionTracker.class.php
+++ b/wcfsetup/install/files/lib/data/article/ArticleVersionTracker.class.php
@@ -15,8 +15,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  Article         getDecoratedObject()
  * @mixin   Article
+ * @extends DatabaseObjectDecorator<Article>
  */
 class ArticleVersionTracker extends DatabaseObjectDecorator implements IVersionTrackerObject
 {
@@ -43,6 +43,7 @@ public function getObjectID()
      * Adds an article content object as child.
      *
      * @param ArticleContent $content article content object
+     * @return void
      */
     public function addContent(ArticleContent $content)
     {
@@ -53,6 +54,7 @@ public function addContent(ArticleContent $content)
      * Sets the list of article content objects.
      *
      * @param ArticleContent[] $content article content objects
+     * @return void
      */
     public function setContent(array $content)
     {
diff --git a/wcfsetup/install/files/lib/data/article/LikeableArticle.class.php b/wcfsetup/install/files/lib/data/article/LikeableArticle.class.php
index fa4aa49110c..0044605aa30 100644
--- a/wcfsetup/install/files/lib/data/article/LikeableArticle.class.php
+++ b/wcfsetup/install/files/lib/data/article/LikeableArticle.class.php
@@ -17,8 +17,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Article getDecoratedObject()
  * @mixin   Article
+ * @extends AbstractLikeObject<Article>
  */
 class LikeableArticle extends AbstractLikeObject implements IReactionObject
 {
diff --git a/wcfsetup/install/files/lib/data/article/LikeableArticleProvider.class.php b/wcfsetup/install/files/lib/data/article/LikeableArticleProvider.class.php
index 2d4180b09d0..9a2985b7209 100644
--- a/wcfsetup/install/files/lib/data/article/LikeableArticleProvider.class.php
+++ b/wcfsetup/install/files/lib/data/article/LikeableArticleProvider.class.php
@@ -16,8 +16,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  LikeableArticle     getObjectByID($objectID)
- * @method  LikeableArticle[]       getObjectsByIDs(array $objectIDs)
+ * @extends AbstractObjectTypeProvider<LikeableArticle>
+ * @implements ILikeObjectTypeProvider<LikeableArticle>
  */
 class LikeableArticleProvider extends AbstractObjectTypeProvider implements
     ILikeObjectTypeProvider,
diff --git a/wcfsetup/install/files/lib/data/article/ViewableArticle.class.php b/wcfsetup/install/files/lib/data/article/ViewableArticle.class.php
index 6ca75f8b05e..5b0e10ee102 100644
--- a/wcfsetup/install/files/lib/data/article/ViewableArticle.class.php
+++ b/wcfsetup/install/files/lib/data/article/ViewableArticle.class.php
@@ -24,10 +24,10 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method          Article                 getDecoratedObject()
  * @method          ArticleContent|ViewableArticleContent|null   getArticleContent()
  * @mixin           Article
  * @property-read   int|null $visitTime  last time the active user has visited the time or `null` if object has not been fetched via `ViewableArticleList` or if the active user is a guest
+ * @extends DatabaseObjectDecorator<Article>
  */
 class ViewableArticle extends DatabaseObjectDecorator
 {
@@ -114,7 +114,7 @@ public function getUserProfile()
     /**
      * Sets the article's content.
      *
-     * @param ViewableArticleContent $articleContent
+     * @return void
      */
     public function setArticleContent(ViewableArticleContent $articleContent)
     {
@@ -193,7 +193,7 @@ public function isNew()
     /**
      * Adds a label.
      *
-     * @param Label $label
+     * @return void
      */
     public function addLabel(Label $label)
     {
diff --git a/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php b/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
index f7c27db127b..030f9baa529 100644
--- a/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
+++ b/wcfsetup/install/files/lib/data/article/ViewableArticleList.class.php
@@ -17,11 +17,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ViewableArticle     current()
- * @method  ViewableArticle[]   getObjects()
- * @method  ViewableArticle|null    getSingleObject()
- * @method  ViewableArticle|null    search($objectID)
- * @property    ViewableArticle[] $objects
+ * @extends ArticleList<ViewableArticle>
  */
 class ViewableArticleList extends ArticleList
 {
@@ -130,6 +126,7 @@ public function readObjects()
      * Enables/disables the loading of article content objects.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableContentLoading($enable = true)
     {
diff --git a/wcfsetup/install/files/lib/data/article/category/ArticleCategory.class.php b/wcfsetup/install/files/lib/data/article/category/ArticleCategory.class.php
index 386136c8f94..bc37bb761bf 100644
--- a/wcfsetup/install/files/lib/data/article/category/ArticleCategory.class.php
+++ b/wcfsetup/install/files/lib/data/article/category/ArticleCategory.class.php
@@ -44,7 +44,7 @@ class ArticleCategory extends AbstractDecoratedCategory implements IAccessibleOb
     /**
      * acl permissions of this category grouped by the id of the user they
      * belong to
-     * @var array
+     * @var array<int, array<string, mixed>>
      */
     protected $userPermissions = [];
 
@@ -72,7 +72,8 @@ public function isAccessible(?User $user = null)
     }
 
     /**
-     * @inheritDoc
+     * @param string $permission
+     * @return mixed
      */
     public function getPermission($permission, ?User $user = null)
     {
diff --git a/wcfsetup/install/files/lib/data/article/category/ArticleCategoryCache.class.php b/wcfsetup/install/files/lib/data/article/category/ArticleCategoryCache.class.php
index 1472b26c789..5ba8bc2e026 100644
--- a/wcfsetup/install/files/lib/data/article/category/ArticleCategoryCache.class.php
+++ b/wcfsetup/install/files/lib/data/article/category/ArticleCategoryCache.class.php
@@ -21,12 +21,14 @@ class ArticleCategoryCache extends SingletonFactory
 {
     /**
      * number of total articles
-     * @var int[]
+     * @var array<int, int>
      */
     protected $articles;
 
     /**
      * Calculates the number of articles.
+     *
+     * @return void
      */
     protected function initArticles()
     {
diff --git a/wcfsetup/install/files/lib/data/article/content/ArticleContentAction.class.php b/wcfsetup/install/files/lib/data/article/content/ArticleContentAction.class.php
index 557d44a5838..cfc90b8875b 100644
--- a/wcfsetup/install/files/lib/data/article/content/ArticleContentAction.class.php
+++ b/wcfsetup/install/files/lib/data/article/content/ArticleContentAction.class.php
@@ -15,8 +15,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ArticleContentEditor[]  getObjects()
- * @method  ArticleContentEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ArticleContent, ArticleContentEditor>
  */
 class ArticleContentAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/article/content/ArticleContentEditor.class.php b/wcfsetup/install/files/lib/data/article/content/ArticleContentEditor.class.php
index 71dd5cd3447..7b226cc884e 100644
--- a/wcfsetup/install/files/lib/data/article/content/ArticleContentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/article/content/ArticleContentEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static ArticleContent  create(array $parameters = [])
- * @method      ArticleContent  getDecoratedObject()
  * @mixin       ArticleContent
+ * @extends DatabaseObjectEditor<ArticleContent>
  */
 class ArticleContentEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/article/content/ArticleContentList.class.php b/wcfsetup/install/files/lib/data/article/content/ArticleContentList.class.php
index 2d34bfafa51..6e02250b3af 100644
--- a/wcfsetup/install/files/lib/data/article/content/ArticleContentList.class.php
+++ b/wcfsetup/install/files/lib/data/article/content/ArticleContentList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\article\content;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -12,11 +13,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ArticleContent      current()
- * @method  ArticleContent[]    getObjects()
- * @method  ArticleContent|null getSingleObject()
- * @method  ArticleContent|null search($objectID)
- * @property    ArticleContent[] $objects
+ * @template TDatabaseObject of ArticleContent|DatabaseObjectDecorator<ArticleContent> = ArticleContent
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class ArticleContentList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/article/content/ViewableArticleContent.class.php b/wcfsetup/install/files/lib/data/article/content/ViewableArticleContent.class.php
index 8d580147009..5719bd21578 100644
--- a/wcfsetup/install/files/lib/data/article/content/ViewableArticleContent.class.php
+++ b/wcfsetup/install/files/lib/data/article/content/ViewableArticleContent.class.php
@@ -14,8 +14,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ArticleContent  getDecoratedObject()
  * @mixin   ArticleContent
+ * @extends DatabaseObjectDecorator<ArticleContent>
  */
 class ViewableArticleContent extends DatabaseObjectDecorator
 {
@@ -59,7 +59,7 @@ public function getArticle()
     /**
      * Sets the article objects.
      *
-     * @param ViewableArticle $article
+     * @return void
      */
     public function setArticle(ViewableArticle $article)
     {
@@ -89,7 +89,7 @@ public function getImage()
     /**
      * Sets the article's image.
      *
-     * @param ViewableMedia $image
+     * @return void
      */
     public function setImage(ViewableMedia $image)
     {
@@ -121,7 +121,7 @@ public function getTeaserImage()
     /**
      * Sets the article's teaser image.
      *
-     * @param ViewableMedia $image
+     * @return void
      */
     public function setTeaserImage(ViewableMedia $image)
     {
diff --git a/wcfsetup/install/files/lib/data/article/content/ViewableArticleContentList.class.php b/wcfsetup/install/files/lib/data/article/content/ViewableArticleContentList.class.php
index 42119d1a276..40b1bdef07c 100644
--- a/wcfsetup/install/files/lib/data/article/content/ViewableArticleContentList.class.php
+++ b/wcfsetup/install/files/lib/data/article/content/ViewableArticleContentList.class.php
@@ -14,11 +14,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ViewableArticleContent      current()
- * @method  ViewableArticleContent[]    getObjects()
- * @method  ViewableArticleContent|null getSingleObject()
- * @method  ViewableArticleContent|null search($objectID)
- * @property    ViewableArticleContent[] $objects
+ * @extends ArticleContentList<ViewableArticleContent>
  */
 class ViewableArticleContentList extends ArticleContentList
 {
diff --git a/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachment.class.php b/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachment.class.php
index dede3d7d55a..871c6bf16a9 100644
--- a/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachment.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachment.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Attachment  getDecoratedObject()
  * @mixin   Attachment
  * @property-read string $username
+ * @extends DatabaseObjectDecorator<Attachment>
  */
 class AdministrativeAttachment extends DatabaseObjectDecorator
 {
diff --git a/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachmentList.class.php b/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachmentList.class.php
index 8ea4c893b2b..47162945b61 100644
--- a/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachmentList.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/AdministrativeAttachmentList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  AdministrativeAttachment    current()
- * @method  AdministrativeAttachment[]  getObjects()
- * @method  AdministrativeAttachment|null   getSingleObject()
- * @method  AdministrativeAttachment|null   search($objectID)
- * @property    AdministrativeAttachment[] $objects
+ * @extends AttachmentList<AdministrativeAttachment>
  */
 class AdministrativeAttachmentList extends AttachmentList
 {
diff --git a/wcfsetup/install/files/lib/data/attachment/Attachment.class.php b/wcfsetup/install/files/lib/data/attachment/Attachment.class.php
index c0add7d758d..232bd40cf95 100644
--- a/wcfsetup/install/files/lib/data/attachment/Attachment.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/Attachment.class.php
@@ -61,7 +61,7 @@ class Attachment extends DatabaseObject implements ILinkableObject, IRouteContro
 
     /**
      * user permissions for attachment access
-     * @var bool[]
+     * @var array<string, bool>
      */
     protected $permissions = [];
 
@@ -151,7 +151,8 @@ protected function getPermission($permission)
     /**
      * Sets the permissions for attachment access.
      *
-     * @param bool[] $permissions
+     * @param array<string, bool> $permissions
+     * @return void
      */
     public function setPermissions(array $permissions)
     {
@@ -210,6 +211,7 @@ public function getThumbnailLocation($size = '')
      * include the `.bin` suffix.
      *
      * @since   5.2
+     * @return void
      * @deprecated 6.1 This will no longer be required once the attachments have been migrated.
      */
     public function migrateStorage()
@@ -282,6 +284,8 @@ public function getTitle(): string
 
     /**
      * Marks this attachment as embedded.
+     *
+     * @return void
      */
     public function markAsEmbedded()
     {
diff --git a/wcfsetup/install/files/lib/data/attachment/AttachmentAction.class.php b/wcfsetup/install/files/lib/data/attachment/AttachmentAction.class.php
index d913269c8f1..11bc81370fd 100644
--- a/wcfsetup/install/files/lib/data/attachment/AttachmentAction.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/AttachmentAction.class.php
@@ -17,9 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Attachment      create()
- * @method  AttachmentEditor[]  getObjects()
- * @method  AttachmentEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Attachment, AttachmentEditor>
  */
 class AttachmentAction extends AbstractDatabaseObjectAction
 {
@@ -36,7 +34,7 @@ class AttachmentAction extends AbstractDatabaseObjectAction
 
     /**
      * current data, used to communicate with event listeners.
-     * @var array
+     * @var mixed[]
      */
     public $eventData = [];
 
@@ -65,6 +63,7 @@ public function validateDelete()
     /**
      * Generates thumbnails.
      *
+     * @return void
      * @deprecated 6.1
      */
     public function generateThumbnails()
@@ -74,6 +73,8 @@ public function generateThumbnails()
 
     /**
      * Copies attachments from one object id to another.
+     *
+     * @return array{attachmentIDs: array<int, int>}
      */
     public function copy()
     {
diff --git a/wcfsetup/install/files/lib/data/attachment/AttachmentEditor.class.php b/wcfsetup/install/files/lib/data/attachment/AttachmentEditor.class.php
index be58fdddb7d..69946645af5 100644
--- a/wcfsetup/install/files/lib/data/attachment/AttachmentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/AttachmentEditor.class.php
@@ -15,9 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Attachment  create(array $parameters = [])
- * @method      Attachment  getDecoratedObject()
  * @mixin       Attachment
+ * @extends DatabaseObjectEditor<Attachment>
  */
 class AttachmentEditor extends DatabaseObjectEditor
 {
@@ -53,7 +52,9 @@ public static function deleteAll(array $objectIDs = [])
                 " . $conditionBuilder;
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute($conditionBuilder->getParameters());
+        // @phpstan-ignore argument.templateType
         while ($attachment = $statement->fetchObject(static::$baseClass)) {
+            /** @var Attachment $attachment */
             $editor = new self($attachment);
             $editor->deleteFiles();
         }
@@ -63,6 +64,8 @@ public static function deleteAll(array $objectIDs = [])
 
     /**
      * Deletes attachment files.
+     *
+     * @return void
      */
     public function deleteFiles()
     {
diff --git a/wcfsetup/install/files/lib/data/attachment/AttachmentList.class.php b/wcfsetup/install/files/lib/data/attachment/AttachmentList.class.php
index 77636895d63..9e5650610c3 100644
--- a/wcfsetup/install/files/lib/data/attachment/AttachmentList.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/AttachmentList.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\data\attachment;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 use wcf\system\cache\runtime\FileRuntimeCache;
 
@@ -12,11 +14,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Attachment      current()
- * @method  Attachment[]        getObjects()
- * @method  Attachment|null     getSingleObject()
- * @method  Attachment|null     search($objectID)
- * @property    Attachment[] $objects
+ * @template-covariant TDatabaseObject of Attachment|DatabaseObjectDecorator = Attachment
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class AttachmentList extends DatabaseObjectList
 {
@@ -25,6 +24,9 @@ class AttachmentList extends DatabaseObjectList
      */
     public $className = Attachment::class;
 
+    /**
+     * @var bool
+     */
     public $enableFileLoading = true;
 
     #[\Override]
diff --git a/wcfsetup/install/files/lib/data/attachment/GroupedAttachmentList.class.php b/wcfsetup/install/files/lib/data/attachment/GroupedAttachmentList.class.php
index ff36fcabfde..0b6add691d5 100644
--- a/wcfsetup/install/files/lib/data/attachment/GroupedAttachmentList.class.php
+++ b/wcfsetup/install/files/lib/data/attachment/GroupedAttachmentList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\attachment;
 
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 
 /**
@@ -15,13 +16,13 @@ class GroupedAttachmentList extends AttachmentList
 {
     /**
      * grouped objects
-     * @var array
+     * @var array<int, array<int, Attachment>>
      */
     public $groupedObjects = [];
 
     /**
      * object type
-     * @var \wcf\data\object\type\ObjectType
+     * @var ObjectType
      */
     protected $objectType;
 
@@ -89,7 +90,8 @@ public function readObjects()
     /**
      * Sets the permissions for attachment access.
      *
-     * @param bool[] $permissions
+     * @param array<string, bool> $permissions
+     * @return void
      */
     public function setPermissions(array $permissions)
     {
diff --git a/wcfsetup/install/files/lib/data/bbcode/BBCode.class.php b/wcfsetup/install/files/lib/data/bbcode/BBCode.class.php
index fe8f50bfdea..80e08b55a93 100644
--- a/wcfsetup/install/files/lib/data/bbcode/BBCode.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/BBCode.class.php
@@ -32,7 +32,7 @@ class BBCode extends ProcessibleDatabaseObject implements IRouteController
 {
     /**
      * list of attributes
-     * @var BBCodeAttribute[]
+     * @var list<BBCodeAttribute>
      */
     protected $attributes;
 
@@ -54,7 +54,7 @@ class BBCode extends ProcessibleDatabaseObject implements IRouteController
     /**
      * Returns the attributes of this bbcode.
      *
-     * @return  BBCodeAttribute[]
+     * @return list<BBCodeAttribute>
      */
     public function getAttributes()
     {
@@ -68,7 +68,8 @@ public function getAttributes()
     /**
      * Sets the attributes of this bbcode.
      *
-     * @param BBCodeAttribute[] $attributes list of attributes
+     * @param list<BBCodeAttribute> $attributes list of attributes
+     * @return void
      */
     public function setAttributes(array $attributes)
     {
@@ -86,8 +87,8 @@ public function getTitle(): string
     /**
      * Returns the button label in the active user's language.
      *
-     * @return  string
-     * @since   5.2
+     * @return string
+     * @since 5.2
      */
     public function getButtonLabel()
     {
@@ -98,7 +99,7 @@ public function getButtonLabel()
      * Returns BBCode object with the given tag.
      *
      * @param string $tag
-     * @return  BBCode
+     * @return BBCode
      */
     public static function getBBCodeByTag($tag)
     {
@@ -122,7 +123,7 @@ public static function getBBCodeByTag($tag)
      *
      * @param string $bbcodeTag
      * @param string[] $allowedBBCodeTags
-     * @return  bool
+     * @return bool
      */
     public static function isAllowedBBCode($bbcodeTag, array $allowedBBCodeTags)
     {
@@ -147,7 +148,7 @@ public static function isAllowedBBCode($bbcodeTag, array $allowedBBCodeTags)
     /**
      * Returns true if this BBCode can be deleted.
      *
-     * @return  bool
+     * @return bool
      */
     public function canDelete()
     {
diff --git a/wcfsetup/install/files/lib/data/bbcode/BBCodeAction.class.php b/wcfsetup/install/files/lib/data/bbcode/BBCodeAction.class.php
index e53369159ff..e5b120d2978 100644
--- a/wcfsetup/install/files/lib/data/bbcode/BBCodeAction.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/BBCodeAction.class.php
@@ -16,8 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCodeEditor[]  getObjects()
- * @method  BBCodeEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BBCode, BBCodeEditor>
  */
 class BBCodeAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/BBCodeCache.class.php b/wcfsetup/install/files/lib/data/bbcode/BBCodeCache.class.php
index ca6a8c0a1c9..64558b05b06 100644
--- a/wcfsetup/install/files/lib/data/bbcode/BBCodeCache.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/BBCodeCache.class.php
@@ -17,7 +17,7 @@ class BBCodeCache extends SingletonFactory
 {
     /**
      * cached bbcodes
-     * @var BBCode[]
+     * @var array<string, BBCode>
      */
     protected $cachedBBCodes = [];
 
@@ -26,14 +26,13 @@ class BBCodeCache extends SingletonFactory
      */
     protected function init()
     {
-        // get bbcode cache
         $this->cachedBBCodes = BBCodeCacheBuilder::getInstance()->getData([], 'bbcodes');
     }
 
     /**
      * Returns all bbcodes.
      *
-     * @return  BBCode[]
+     * @return array<string, BBCode>
      */
     public function getBBCodes()
     {
@@ -44,7 +43,7 @@ public function getBBCodes()
      * Returns the BBCode with the given tag or `null` if no such BBCode exists.
      *
      * @param string $tag
-     * @return  BBCode|null
+     * @return ?BBCode
      */
     public function getBBCodeByTag($tag)
     {
@@ -55,7 +54,7 @@ public function getBBCodeByTag($tag)
      * Returns all attributes of a bbcode.
      *
      * @param string $tag
-     * @return  BBCodeAttribute[]
+     * @return list<BBCodeAttribute>
      */
     public function getBBCodeAttributes($tag)
     {
diff --git a/wcfsetup/install/files/lib/data/bbcode/BBCodeEditor.class.php b/wcfsetup/install/files/lib/data/bbcode/BBCodeEditor.class.php
index 48760a7721c..cdf5bd0386d 100644
--- a/wcfsetup/install/files/lib/data/bbcode/BBCodeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/BBCodeEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static BBCode      create(array $parameters = [])
- * @method      BBCode      getDecoratedObject()
  * @mixin       BBCode
+ * @extends DatabaseObjectEditor<BBCode>
+ * @implements IEditableCachedObject<BBCode>
  */
 class BBCodeEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/BBCodeList.class.php b/wcfsetup/install/files/lib/data/bbcode/BBCodeList.class.php
index 60d57885183..0f94adffc7b 100644
--- a/wcfsetup/install/files/lib/data/bbcode/BBCodeList.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/BBCodeList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCode      current()
- * @method  BBCode[]    getObjects()
- * @method  BBCode|null getSingleObject()
- * @method  BBCode|null search($objectID)
- * @property    BBCode[] $objects
+ * @extends DatabaseObjectList<BBCode>
  */
 class BBCodeList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/MessagePreviewAction.class.php b/wcfsetup/install/files/lib/data/bbcode/MessagePreviewAction.class.php
index ea86aa36b37..290118881e5 100644
--- a/wcfsetup/install/files/lib/data/bbcode/MessagePreviewAction.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/MessagePreviewAction.class.php
@@ -27,6 +27,8 @@ class MessagePreviewAction extends BBCodeAction
 
     /**
      * Validates parameters for message preview.
+     *
+     * @return void
      */
     public function validateGetMessagePreview()
     {
@@ -46,8 +48,8 @@ public function validateGetMessagePreview()
     /**
      * Returns a rendered message preview.
      *
-     * @return  array
-     * @throws  UserInputException
+     * @return array{message: string, raw: string}
+     * @throws UserInputException
      */
     public function getMessagePreview()
     {
diff --git a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeAction.class.php b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeAction.class.php
index 925aca6e093..cf049c30c26 100644
--- a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeAction.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCodeAttribute         create()
- * @method  BBCodeAttributeEditor[]     getObjects()
- * @method  BBCodeAttributeEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BBCodeAttribute, BBCodeAttributeEditor>
  */
 class BBCodeAttributeAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeEditor.class.php b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeEditor.class.php
index 9c9b72d8483..4fc68529146 100644
--- a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static BBCodeAttribute     create(array $parameters = [])
- * @method      BBCodeAttribute     getDecoratedObject()
  * @mixin       BBCodeAttribute
+ * @extends DatabaseObjectEditor<BBCodeAttribute>
  */
 class BBCodeAttributeEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeList.class.php b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeList.class.php
index abe48e7a196..5214d177019 100644
--- a/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeList.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/attribute/BBCodeAttributeList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCodeAttribute     current()
- * @method  BBCodeAttribute[]   getObjects()
- * @method  BBCodeAttribute|null    getSingleObject()
- * @method  BBCodeAttribute|null    search($objectID)
- * @property    BBCodeAttribute[] $objects
+ * @extends DatabaseObjectList<BBCodeAttribute>
  */
 class BBCodeAttributeList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderAction.class.php b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderAction.class.php
index 1a0b2886e24..3e79c11cea1 100644
--- a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderAction.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderAction.class.php
@@ -13,9 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCodeMediaProvider     create()
- * @method  BBCodeMediaProviderEditor[] getObjects()
- * @method  BBCodeMediaProviderEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BBCodeMediaProvider, BBCodeMediaProviderEditor>
  */
 class BBCodeMediaProviderAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderEditor.class.php b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderEditor.class.php
index 20d88687801..1d928649ed7 100644
--- a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderEditor.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static BBCodeMediaProvider create(array $parameters = [])
- * @method      BBCodeMediaProvider getDecoratedObject()
  * @mixin       BBCodeMediaProvider
+ * @extends DatabaseObjectEditor<BBCodeMediaProvider>
+ * @implements IEditableCachedObject<BBCodeMediaProvider>
  */
 class BBCodeMediaProviderEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderList.class.php b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderList.class.php
index ca8d05c65cc..bccb323dc6f 100644
--- a/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderList.class.php
+++ b/wcfsetup/install/files/lib/data/bbcode/media/provider/BBCodeMediaProviderList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCodeMediaProvider     current()
- * @method  BBCodeMediaProvider[]       getObjects()
- * @method  BBCodeMediaProvider|null    getSingleObject()
- * @method  BBCodeMediaProvider|null    search($objectID)
- * @property    BBCodeMediaProvider[] $objects
+ * @extends DatabaseObjectList<BBCodeMediaProvider>
  */
 class BBCodeMediaProviderList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntry.class.php b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntry.class.php
index da254f4614c..730611ff954 100644
--- a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntry.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntry.class.php
@@ -75,11 +75,20 @@ public static function getMatches($username, $email, $ipAddress)
         return $matches;
     }
 
+    /**
+     * @param string $string
+     * @return string
+     */
     protected static function getHash($string)
     {
         return \hash('sha256', $string, true);
     }
 
+    /**
+     * @param string $type
+     * @param int $occurrences
+     * @return bool
+     */
     protected static function isMatch($type, $occurrences)
     {
         $setting = [
@@ -107,6 +116,10 @@ protected static function isMatch($type, $occurrences)
         return false;
     }
 
+    /**
+     * @param string $type
+     * @return int
+     */
     protected static function get90Percentile($type)
     {
         static $percentile = [];
diff --git a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
index 71b28c7c53f..8d8817df4cd 100644
--- a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
@@ -18,8 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method BlacklistEntryEditor[] getObjects()
- * @method BlacklistEntryEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BlacklistEntry, BlacklistEntryEditor>
  * @since 5.2
  */
 class BlacklistEntryAction extends AbstractDatabaseObjectAction
@@ -29,6 +28,9 @@ class BlacklistEntryAction extends AbstractDatabaseObjectAction
      */
     protected $className = BlacklistEntryEditor::class;
 
+    /**
+     * @return void
+     */
     public function import()
     {
         $client = HttpFactory::makeClientWithTimeout(5);
diff --git a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryEditor.class.php b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryEditor.class.php
index 7939bbbda4f..06c607d1293 100644
--- a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static BlacklistEntry create(array $parameters = [])
- * @method BlacklistEntry getDecoratedObject()
  * @mixin BlacklistEntry
+ * @extends DatabaseObjectEditor<BlacklistEntry>
  * @since 5.2
  */
 class BlacklistEntryEditor extends DatabaseObjectEditor
diff --git a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryList.class.php b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryList.class.php
index e452236bd29..4ddd5a1d23f 100644
--- a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryList.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryList.class.php
@@ -11,10 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method BlacklistEntry current()
- * @method BlacklistEntry[] getObjects()
- * @method BlacklistEntry|null search($objectID)
- * @property BlacklistEntry[] $objects
+ * @extends DatabaseObjectList<BlacklistEntry>
  * @since 5.2
  */
 class BlacklistEntryList extends DatabaseObjectList
diff --git a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusAction.class.php b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusAction.class.php
index 76fe6a2aa2a..a217eceff62 100644
--- a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusAction.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusAction.class.php
@@ -11,8 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method BlacklistStatusEditor[] getObjects()
- * @method BlacklistStatusEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BlacklistStatus, BlacklistStatusEditor>
  * @since 5.2
  */
 class BlacklistStatusAction extends AbstractDatabaseObjectAction
diff --git a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusEditor.class.php b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusEditor.class.php
index aff99754b3b..6f9c7373ec0 100644
--- a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusEditor.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static BlacklistStatus create(array $parameters = [])
- * @method BlacklistStatus getDecoratedObject()
  * @mixin BlacklistStatus
+ * @extends DatabaseObjectEditor<BlacklistStatus>
  * @since 5.2
  */
 class BlacklistStatusEditor extends DatabaseObjectEditor
diff --git a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusList.class.php b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusList.class.php
index a827b74f8bd..b1f6af62194 100644
--- a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusList.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatusList.class.php
@@ -11,10 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method BlacklistStatus current()
- * @method BlacklistStatus[] getObjects()
- * @method BlacklistStatus|null search($objectID)
- * @property BlacklistStatus[] $objects
+ * @extends DatabaseObjectList<BlacklistStatus>
  * @since 5.2
  */
 class BlacklistStatusList extends DatabaseObjectList
diff --git a/wcfsetup/install/files/lib/data/box/Box.class.php b/wcfsetup/install/files/lib/data/box/Box.class.php
index f4a997eb3ad..5f6c417251b 100644
--- a/wcfsetup/install/files/lib/data/box/Box.class.php
+++ b/wcfsetup/install/files/lib/data/box/Box.class.php
@@ -46,7 +46,7 @@
  * @property-read   int|null $linkPageID     id of the (internal) page the box image and box title are linking to or `null` if no internal page is linked
  * @property-read   int $linkPageObjectID   id of the object the (internal) page links refers to or `0` if no internal link is used or no specific object is linked
  * @property-read   string $externalURL        external link used to for the box image and box title or empty if no external link is set
- * @property-read   array $additionalData     array with additional data of the box
+ * @property-read   mixed[] $additionalData     array with additional data of the box
  * @property-read   int|null $limit          number of objects shown in the box for `AbstractDatabaseObjectListBoxController` controllers or `null` otherwise
  * @property-read   string|null $sortField      sort field of the objects shown in the box for `AbstractDatabaseObjectListBoxController` controllers or `null` otherwise
  * @property-read   string|null $sortOrder      sort order of the objects shown in the box for `AbstractDatabaseObjectListBoxController` controllers or `null` otherwise
@@ -224,6 +224,7 @@ public function getBoxContents()
      * Sets the box's content.
      *
      * @param BoxContent[] $boxContents
+     * @return void
      */
     public function setBoxContents($boxContents)
     {
@@ -608,6 +609,7 @@ public function isAccessible()
      * Sets the virtual show order of this box.
      *
      * @param int $virtualShowOrder
+     * @return void
      */
     public function setVirtualShowOrder($virtualShowOrder)
     {
diff --git a/wcfsetup/install/files/lib/data/box/BoxAction.class.php b/wcfsetup/install/files/lib/data/box/BoxAction.class.php
index 4d3a6f10b2d..a3a46ee01d2 100644
--- a/wcfsetup/install/files/lib/data/box/BoxAction.class.php
+++ b/wcfsetup/install/files/lib/data/box/BoxAction.class.php
@@ -25,8 +25,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  BoxEditor[] getObjects()
- * @method  BoxEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Box, BoxEditor>
  */
 class BoxAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
@@ -295,6 +294,8 @@ public function delete()
 
     /**
      * Validates the 'getBoxConditionsTemplate' action.
+     *
+     * @return void
      */
     public function validateGetBoxConditionsTemplate()
     {
diff --git a/wcfsetup/install/files/lib/data/box/BoxEditor.class.php b/wcfsetup/install/files/lib/data/box/BoxEditor.class.php
index f31fdbf2fe0..6a7ddec57bc 100644
--- a/wcfsetup/install/files/lib/data/box/BoxEditor.class.php
+++ b/wcfsetup/install/files/lib/data/box/BoxEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static Box create(array $parameters = [])
- * @method      Box getDecoratedObject()
  * @mixin       Box
+ * @extends DatabaseObjectEditor<Box>
  */
 class BoxEditor extends DatabaseObjectEditor
 {
@@ -28,6 +27,7 @@ class BoxEditor extends DatabaseObjectEditor
      *
      * @param int $languageID
      * @param string $content
+     * @return void
      */
     public function writeTemplate($languageID, $content)
     {
diff --git a/wcfsetup/install/files/lib/data/box/BoxList.class.php b/wcfsetup/install/files/lib/data/box/BoxList.class.php
index a7bf86f2c54..dc92e80a365 100644
--- a/wcfsetup/install/files/lib/data/box/BoxList.class.php
+++ b/wcfsetup/install/files/lib/data/box/BoxList.class.php
@@ -14,11 +14,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Box     current()
- * @method  Box[]       getObjects()
- * @method  Box|null    getSingleObject()
- * @method  Box|null    search($objectID)
- * @property    Box[] $objects
+ * @extends DatabaseObjectList<Box>
  */
 class BoxList extends DatabaseObjectList
 {
@@ -63,6 +59,7 @@ public function readObjects()
      * Enables/disables the loading of box content objects.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableContentLoading($enable = true)
     {
diff --git a/wcfsetup/install/files/lib/data/box/BoxVersionTracker.class.php b/wcfsetup/install/files/lib/data/box/BoxVersionTracker.class.php
index bd936184ac7..4fcadc16cb1 100644
--- a/wcfsetup/install/files/lib/data/box/BoxVersionTracker.class.php
+++ b/wcfsetup/install/files/lib/data/box/BoxVersionTracker.class.php
@@ -15,8 +15,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  Box     getDecoratedObject()
  * @mixin   Box
+ * @extends DatabaseObjectDecorator<Box>
  */
 class BoxVersionTracker extends DatabaseObjectDecorator implements IVersionTrackerObject
 {
@@ -43,6 +43,7 @@ public function getObjectID()
      * Adds an box content object as child.
      *
      * @param BoxContent $content box content object
+     * @return void
      */
     public function addContent(BoxContent $content)
     {
@@ -53,6 +54,7 @@ public function addContent(BoxContent $content)
      * Sets the list of box content objects.
      *
      * @param BoxContent[] $content box content objects
+     * @return void
      */
     public function setContent(array $content)
     {
diff --git a/wcfsetup/install/files/lib/data/box/content/BoxContent.class.php b/wcfsetup/install/files/lib/data/box/content/BoxContent.class.php
index 9391ca361cd..0bbae521666 100644
--- a/wcfsetup/install/files/lib/data/box/content/BoxContent.class.php
+++ b/wcfsetup/install/files/lib/data/box/content/BoxContent.class.php
@@ -93,7 +93,7 @@ public function getImage()
     /**
      * Sets the image of this box content.
      *
-     * @param ViewableMedia $image
+     * @return void
      */
     public function setImage(ViewableMedia $image)
     {
diff --git a/wcfsetup/install/files/lib/data/box/content/BoxContentAction.class.php b/wcfsetup/install/files/lib/data/box/content/BoxContentAction.class.php
index e531e6e0a25..19ff9a91b32 100644
--- a/wcfsetup/install/files/lib/data/box/content/BoxContentAction.class.php
+++ b/wcfsetup/install/files/lib/data/box/content/BoxContentAction.class.php
@@ -12,8 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  BoxContentEditor[]  getObjects()
- * @method  BoxContentEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<BoxContent, BoxContentEditor>
  */
 class BoxContentAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/box/content/BoxContentEditor.class.php b/wcfsetup/install/files/lib/data/box/content/BoxContentEditor.class.php
index 12e79f6681c..09d753207ec 100644
--- a/wcfsetup/install/files/lib/data/box/content/BoxContentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/box/content/BoxContentEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static BoxContent  create(array $parameters = [])
- * @method      BoxContent  getDecoratedObject()
  * @mixin       BoxContent
+ * @extends DatabaseObjectEditor<BoxContent>
  */
 class BoxContentEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/box/content/BoxContentList.class.php b/wcfsetup/install/files/lib/data/box/content/BoxContentList.class.php
index d59e724614c..3162cd04639 100644
--- a/wcfsetup/install/files/lib/data/box/content/BoxContentList.class.php
+++ b/wcfsetup/install/files/lib/data/box/content/BoxContentList.class.php
@@ -14,11 +14,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  BoxContent      current()
- * @method  BoxContent[]            getObjects()
- * @method  BoxContent|null         getSingleObject()
- * @method  BoxContent|null         search($objectID)
- * @property    BoxContent[] $objects
+ * @extends DatabaseObjectList<BoxContent>
  */
 class BoxContentList extends DatabaseObjectList
 {
@@ -86,6 +82,7 @@ public function readObjects()
      * Enables/disables the loading of box content images.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableImageLoading($enable = true)
     {
@@ -96,6 +93,7 @@ public function enableImageLoading($enable = true)
      * Enables/disables the loading of embedded objects.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableEmbeddedObjectLoading($enable = true)
     {
diff --git a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionAction.class.php b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionAction.class.php
index abb4fcd1c40..52651d3201c 100644
--- a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionAction.class.php
+++ b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CaptchaQuestionEditor[]     getObjects()
- * @method  CaptchaQuestionEditor       getSingleObject()
- * @property    CaptchaQuestionEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<CaptchaQuestion, CaptchaQuestionEditor>
  */
 class CaptchaQuestionAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
@@ -33,6 +31,9 @@ class CaptchaQuestionAction extends AbstractDatabaseObjectAction implements ITog
      */
     protected $permissionsUpdate = ['admin.captcha.canManageCaptchaQuestion'];
 
+    /**
+     * @return array<string, string>
+     */
     #[\Override]
     public function getI18nSaveTypes(): array
     {
diff --git a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionEditor.class.php b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionEditor.class.php
index ca8ca6919c8..839dea59661 100644
--- a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static CaptchaQuestion     create(array $parameters = [])
- * @method      CaptchaQuestion     getDecoratedObject()
  * @mixin       CaptchaQuestion
+ * @extends DatabaseObjectEditor<CaptchaQuestion>
+ * @implements IEditableCachedObject<CaptchaQuestion>
  */
 class CaptchaQuestionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionList.class.php b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionList.class.php
index 2500ce87a71..5cfaa578011 100644
--- a/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionList.class.php
+++ b/wcfsetup/install/files/lib/data/captcha/question/CaptchaQuestionList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CaptchaQuestion     current()
- * @method  CaptchaQuestion[]   getObjects()
- * @method  CaptchaQuestion|null    getSingleObject()
- * @method  CaptchaQuestion|null    search($objectID)
- * @property    CaptchaQuestion[] $objects
+ * @extends DatabaseObjectList<CaptchaQuestion>
  */
-class CaptchaQuestionList extends DatabaseObjectList
-{
-}
+class CaptchaQuestionList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/captcha/question/I18nCaptchaQuestionList.class.php b/wcfsetup/install/files/lib/data/captcha/question/I18nCaptchaQuestionList.class.php
index 439517ac366..4784e731df5 100644
--- a/wcfsetup/install/files/lib/data/captcha/question/I18nCaptchaQuestionList.class.php
+++ b/wcfsetup/install/files/lib/data/captcha/question/I18nCaptchaQuestionList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method      CaptchaQuestion        current()
- * @method      CaptchaQuestion[]      getObjects()
- * @method      CaptchaQuestion|null   getSingleObject()
- * @method      CaptchaQuestion|null   search($objectID)
- * @property    CaptchaQuestion[] $objects
+ * @extends I18nDatabaseObjectList<CaptchaQuestion>
  */
 class I18nCaptchaQuestionList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/category/AbstractDecoratedCategory.class.php b/wcfsetup/install/files/lib/data/category/AbstractDecoratedCategory.class.php
index 7ddf9fa6c07..a8881f2fbb5 100644
--- a/wcfsetup/install/files/lib/data/category/AbstractDecoratedCategory.class.php
+++ b/wcfsetup/install/files/lib/data/category/AbstractDecoratedCategory.class.php
@@ -13,32 +13,35 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category    getDecoratedObject()
- * @mixin   Category
+ * @mixin Category
+ * @template TCategory of Category = Category
+ * @extends DatabaseObjectDecorator<TCategory>
  */
 abstract class AbstractDecoratedCategory extends DatabaseObjectDecorator
 {
     /**
      * list of child categories of this category
-     * @var Category[]
+     *
+     * @var static[]
      */
     protected $childCategories;
 
     /**
      * list of all child categories of this category
-     * @var Category[]
+     *
+     * @var static[]
      */
     protected $allChildCategories;
 
     /**
      * list of all parent category generations of this category
-     * @var AbstractDecoratedCategory[]
+     * @var static[]
      */
     protected $parentCategories;
 
     /**
      * parent category of this category
-     * @var ?AbstractDecoratedCategory
+     * @var ?static
      */
     protected $parentCategory;
 
@@ -48,7 +51,8 @@ abstract class AbstractDecoratedCategory extends DatabaseObjectDecorator
     protected static $baseClass = Category::class;
 
     /**
-     * @inheritDoc
+     * @param string[] $permissions
+     * @return void
      */
     public function checkPermissions(array $permissions)
     {
@@ -60,7 +64,7 @@ public function checkPermissions(array $permissions)
     }
 
     /**
-     * @inheritDoc
+     * @return array<int, static>
      */
     public function getChildCategories()
     {
@@ -75,7 +79,7 @@ public function getChildCategories()
     }
 
     /**
-     * @inheritDoc
+     * @return array<int, static>
      */
     public function getAllChildCategories()
     {
@@ -90,7 +94,7 @@ public function getAllChildCategories()
     }
 
     /**
-     * @inheritDoc
+     * @return array<int, static>
      */
     public function getParentCategories()
     {
@@ -105,7 +109,7 @@ public function getParentCategories()
     }
 
     /**
-     * @inheritDoc
+     * @return static
      */
     public function getParentCategory()
     {
@@ -117,7 +121,7 @@ public function getParentCategory()
     }
 
     /**
-     * @inheritDoc
+     * @return bool
      */
     public function isParentCategory(self $category)
     {
@@ -129,7 +133,7 @@ public function isParentCategory(self $category)
      * category exists.
      *
      * @param int $categoryID
-     * @return  AbstractDecoratedCategory|null
+     * @return ?static
      */
     public static function getCategory($categoryID)
     {
diff --git a/wcfsetup/install/files/lib/data/category/Category.class.php b/wcfsetup/install/files/lib/data/category/Category.class.php
index 5f8e15566d5..d6d602174aa 100644
--- a/wcfsetup/install/files/lib/data/category/Category.class.php
+++ b/wcfsetup/install/files/lib/data/category/Category.class.php
@@ -29,7 +29,7 @@
  * @property-read   int $showOrder      position of the category in relation to its siblings
  * @property-read   int $time           timestamp at which the comment has been created
  * @property-read   int $isDisabled     is `1` if the category is disabled and thus neither accessible nor selectable, otherwise `0`
- * @property-read   array $additionalData     array with additional data of the category
+ * @property-read   mixed[] $additionalData     array with additional data of the category
  */
 class Category extends ProcessibleDatabaseObject implements IPermissionObject, IRouteController
 {
@@ -60,7 +60,7 @@ class Category extends ProcessibleDatabaseObject implements IPermissionObject, I
     /**
      * acl permissions of this category grouped by the id of the user they
      * belong to
-     * @var array
+     * @var array<int, array<string, int>>
      */
     protected $userPermissions = [];
 
diff --git a/wcfsetup/install/files/lib/data/category/CategoryAction.class.php b/wcfsetup/install/files/lib/data/category/CategoryAction.class.php
index 312e6b5c63e..be8b9e11bb1 100644
--- a/wcfsetup/install/files/lib/data/category/CategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/category/CategoryAction.class.php
@@ -24,10 +24,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category        create()
- * @method  CategoryEditor[]    getObjects()
- * @method  CategoryEditor      getSingleObject()
- * @property-read CategoryEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Category, CategoryEditor>
  */
 class CategoryAction extends AbstractDatabaseObjectAction implements
     ISortableAction,
diff --git a/wcfsetup/install/files/lib/data/category/CategoryEditor.class.php b/wcfsetup/install/files/lib/data/category/CategoryEditor.class.php
index 88509e396e1..3e673017b53 100644
--- a/wcfsetup/install/files/lib/data/category/CategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/category/CategoryEditor.class.php
@@ -15,8 +15,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category    getDecoratedObject()
  * @mixin   Category
+ * @extends DatabaseObjectEditor<Category>
+ * @implements IEditableCachedObject<Category>
  */
 class CategoryEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -31,7 +32,7 @@ class CategoryEditor extends DatabaseObjectEditor implements IEditableCachedObje
      *
      * @param int $parentCategoryID
      * @param ?int $showOrder
-     * @return  int
+     * @return int
      */
     public function updateShowOrder($parentCategoryID, $showOrder)
     {
@@ -108,7 +109,6 @@ public function updateShowOrder($parentCategoryID, $showOrder)
 
     /**
      * @inheritDoc
-     * @return  Category
      */
     public static function create(array $parameters = [])
     {
@@ -129,9 +129,7 @@ public static function create(array $parameters = [])
             $parameters['additionalData'] = \serialize([]);
         }
 
-        $object = parent::create($parameters);
-        \assert($object instanceof Category);
-        return $object;
+        return parent::create($parameters);
     }
 
     /**
@@ -160,7 +158,7 @@ public static function deleteAll(array $objectIDs = [])
      * @param int $objectTypeID
      * @param int $parentCategoryID
      * @param ?int $showOrder
-     * @return  int
+     * @return int
      */
     protected static function getShowOrder($objectTypeID, $parentCategoryID, $showOrder)
     {
diff --git a/wcfsetup/install/files/lib/data/category/CategoryList.class.php b/wcfsetup/install/files/lib/data/category/CategoryList.class.php
index e9151aeeb00..4c1ba4386dd 100644
--- a/wcfsetup/install/files/lib/data/category/CategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/category/CategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category    current()
- * @method  Category[]  getObjects()
- * @method  Category|null   getSingleObject()
- * @method  Category|null   search($objectID)
- * @property    Category[] $objects
+ * @extends DatabaseObjectList<Category>
  */
 class CategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/category/CategoryNode.class.php b/wcfsetup/install/files/lib/data/category/CategoryNode.class.php
index aa6eb22ff9a..c11b600427e 100644
--- a/wcfsetup/install/files/lib/data/category/CategoryNode.class.php
+++ b/wcfsetup/install/files/lib/data/category/CategoryNode.class.php
@@ -14,8 +14,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category    getDecoratedObject()
  * @mixin   Category
+ * @extends DatabaseObjectDecorator<Category>
  */
 class CategoryNode extends DatabaseObjectDecorator implements IObjectTreeNode
 {
diff --git a/wcfsetup/install/files/lib/data/category/CategoryNodeTree.class.php b/wcfsetup/install/files/lib/data/category/CategoryNodeTree.class.php
index 864dfe6b777..ffa8a6d92f0 100644
--- a/wcfsetup/install/files/lib/data/category/CategoryNodeTree.class.php
+++ b/wcfsetup/install/files/lib/data/category/CategoryNodeTree.class.php
@@ -11,6 +11,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements \IteratorAggregate<int, CategoryNode>
  */
 class CategoryNodeTree implements \IteratorAggregate
 {
@@ -82,6 +84,8 @@ public function __construct(
     /**
      * Sets the maximum depth considered when building the node tree, defaults
      * to -1 which equals infinite.
+     *
+     * @return void
      */
     public function setMaxDepth(int $maxDepth)
     {
@@ -90,6 +94,8 @@ public function setMaxDepth(int $maxDepth)
 
     /**
      * Builds the category node tree.
+     *
+     * @return void
      */
     protected function buildTree()
     {
@@ -99,6 +105,8 @@ protected function buildTree()
 
     /**
      * Builds a certain level of the tree.
+     *
+     * @return void
      */
     protected function buildTreeLevel(CategoryNode $parentNode, int $depth = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/category/UncachedCategoryNodeTree.class.php b/wcfsetup/install/files/lib/data/category/UncachedCategoryNodeTree.class.php
index 6efc9765557..14a81ed484d 100644
--- a/wcfsetup/install/files/lib/data/category/UncachedCategoryNodeTree.class.php
+++ b/wcfsetup/install/files/lib/data/category/UncachedCategoryNodeTree.class.php
@@ -15,13 +15,13 @@ class UncachedCategoryNodeTree extends CategoryNodeTree
 {
     /**
      * locally cached categories
-     * @var Category[]
+     * @var array<int, Category>
      */
     protected $categoryCache = [];
 
     /**
      * locally cached category ids grouped by the id of their parent category
-     * @var array
+     * @var array<int, list<int>>
      */
     protected $categoryStructureCache = [];
 
@@ -52,7 +52,7 @@ protected function buildTree()
     /**
      * @inheritDoc
      */
-    protected function getCategory($categoryID)
+    protected function getCategory(int $categoryID)
     {
         return $this->categoryCache[$categoryID];
     }
diff --git a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionAction.class.php b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionAction.class.php
index 20ab65d770a..03bd30c5d61 100644
--- a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionAction.class.php
+++ b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ClipboardAction         create()
- * @method  ClipboardActionEditor[]     getObjects()
- * @method  ClipboardActionEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ClipboardAction, ClipboardActionEditor>
  */
 class ClipboardActionAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionEditor.class.php b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionEditor.class.php
index 48c1ba9befc..828d5bcc028 100644
--- a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ClipboardAction     create(array $parameters = [])
- * @method      ClipboardAction     getDecoratedObject()
  * @mixin       ClipboardAction
+ * @extends DatabaseObjectEditor<ClipboardAction>
  */
 class ClipboardActionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionList.class.php b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionList.class.php
index b33e177b173..0e9e3d96ac3 100644
--- a/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionList.class.php
+++ b/wcfsetup/install/files/lib/data/clipboard/action/ClipboardActionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ClipboardAction     current()
- * @method  ClipboardAction[]   getObjects()
- * @method  ClipboardAction|null    getSingleObject()
- * @method  ClipboardAction|null    search($objectID)
- * @property    ClipboardAction[] $objects
+ * @extends DatabaseObjectList<ClipboardAction>
  */
 class ClipboardActionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/clipboard/item/ClipboardItemAction.class.php b/wcfsetup/install/files/lib/data/clipboard/item/ClipboardItemAction.class.php
index 1cad937b179..33d58ab2645 100644
--- a/wcfsetup/install/files/lib/data/clipboard/item/ClipboardItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/clipboard/item/ClipboardItemAction.class.php
@@ -3,6 +3,8 @@
 namespace wcf\data\clipboard\item;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectEditor;
 use wcf\system\clipboard\ClipboardEditorItem;
 use wcf\system\clipboard\ClipboardHandler;
 use wcf\system\event\EventHandler;
@@ -16,6 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectAction<DatabaseObject, DatabaseObjectEditor<DatabaseObject>>
  */
 class ClipboardItemAction extends AbstractDatabaseObjectAction
 {
@@ -31,7 +35,8 @@ class ClipboardItemAction extends AbstractDatabaseObjectAction
      * This is a heavily modified constructor which behaves differently from other DBOActions,
      * primarily because this class just masquerades as a regular DBOAction.
      *
-     * @inheritDoc
+     * @param object[] $objects
+     * @param mixed[] $parameters
      */
     public function __construct(array $objects, $action, array $parameters = [])
     {
@@ -44,6 +49,8 @@ public function __construct(array $objects, $action, array $parameters = [])
 
     /**
      * Validates parameters to set an item as marked.
+     *
+     * @return void
      */
     public function validateMark()
     {
@@ -68,6 +75,8 @@ public function mark()
 
     /**
      * Validates parameters to unset an item as marked.
+     *
+     * @return void
      */
     public function validateUnmark()
     {
@@ -88,6 +97,8 @@ public function unmark()
 
     /**
      * Validates parameters to fetch the list of marked items.
+     *
+     * @return void
      */
     public function validateGetMarkedItems()
     {
@@ -106,6 +117,8 @@ public function getMarkedItems()
 
     /**
      * Validates parameters to unmark all items of a type.
+     *
+     * @return void
      */
     public function validateUnmarkAll()
     {
@@ -126,6 +139,8 @@ public function unmarkAll()
 
     /**
      * Validates generic parameters used for most clipboard actions.
+     *
+     * @return void
      */
     protected function validateDefaultParameters()
     {
@@ -136,6 +151,8 @@ protected function validateDefaultParameters()
 
     /**
      * Reads the object type and sets the internal object type id.
+     *
+     * @return void
      */
     protected function readObjectType()
     {
diff --git a/wcfsetup/install/files/lib/data/comment/CommentAction.class.php b/wcfsetup/install/files/lib/data/comment/CommentAction.class.php
index e33ecf1de82..885343f9f5b 100644
--- a/wcfsetup/install/files/lib/data/comment/CommentAction.class.php
+++ b/wcfsetup/install/files/lib/data/comment/CommentAction.class.php
@@ -45,10 +45,7 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment         create()
- * @method  CommentEditor[]     getObjects()
- * @method  CommentEditor       getSingleObject()
- * @property-read CommentEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Comment, CommentEditor>
  */
 class CommentAction extends AbstractDatabaseObjectAction implements IMessageInlineEditorAction
 {
@@ -118,7 +115,7 @@ class CommentAction extends AbstractDatabaseObjectAction implements IMessageInli
 
     /**
      * errors occurring through the validation of addComment or addResponse
-     * @var array
+     * @var array<string, string>
      * @deprecated 6.1
      */
     public $validationErrors = [];
@@ -126,6 +123,7 @@ class CommentAction extends AbstractDatabaseObjectAction implements IMessageInli
     /**
      * Validates parameters to load comments.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -144,7 +142,7 @@ public function validateLoadComments()
     /**
      * Returns parsed comments.
      *
-     * @return  array
+     * @return array{lastCommentTime: int, template: string}
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function loadComments()
@@ -176,6 +174,7 @@ public function loadComments()
     /**
      * Validates the `loadComment` action.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @since   3.1
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
@@ -243,6 +242,7 @@ public function loadComment()
     /**
      * Validates the `loadResponse` action.
      *
+     * @return void
      * @since   3.1
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -284,6 +284,7 @@ public function loadResponse()
     /**
      * Validates parameters to add a comment.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -392,6 +393,7 @@ public function addComment()
     }
 
     /**
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function triggerPublication()
@@ -458,6 +460,7 @@ public function triggerPublication()
     /**
      * Validates parameters to add a response.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -497,7 +500,7 @@ public function validateAddResponse()
     /**
      * Adds a response.
      *
-     * @return  array
+     * @return mixed[]
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function addResponse()
@@ -595,6 +598,8 @@ public function addResponse()
 
     /**
      * Publishes a response.
+     *
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function triggerPublicationResponse()
@@ -705,6 +710,7 @@ public function triggerPublicationResponse()
     /**
      * Validates the `enable` action.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -752,6 +758,8 @@ public function enable()
     /**
      * Validates the `enableResponse` action.
      *
+     *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      * @deprecated 6.0 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
@@ -898,6 +906,7 @@ public function save()
     /**
      * Validates parameters to remove a comment or response.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      * @deprecated 6.0 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
@@ -953,6 +962,7 @@ public function remove()
     }
 
     /**
+     * @return void
      * @since 6.0
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -970,6 +980,7 @@ private function validateGetGuestDialog(): void
      * Returns the dialog for guests when they try to write a comment letting
      * them enter a username and solving a captcha.
      *
+     * @return ?string
      * @throws  SystemException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -1139,6 +1150,7 @@ protected function renderResponse(CommentResponse $response)
     /**
      * Validates message parameters.
      *
+     * @return void
      * @throws      UserInputException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -1228,6 +1240,7 @@ protected function validateObjectType($objectTypeID = null)
     /**
      * Validates comment id parameter.
      *
+     * @return void
      * @throws  UserInputException
      * @deprecated 6.0 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -1244,6 +1257,7 @@ protected function validateCommentID()
     /**
      * Validates response id parameter.
      *
+     * @return void
      * @throws  UserInputException
      * @deprecated 6.0 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -1259,6 +1273,8 @@ protected function validateResponseID()
 
     /**
      * Validates the username parameter.
+     *
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     protected function validateUsername()
@@ -1284,6 +1300,7 @@ protected function validateUsername()
     /**
      * Validates the captcha challenge.
      *
+     * @return void
      * @throws  SystemException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -1318,6 +1335,8 @@ protected function validateCaptcha()
 
     /**
      * Sets the list of disallowed bbcodes for comments.
+     *
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     protected function setDisallowedBBCodes()
diff --git a/wcfsetup/install/files/lib/data/comment/CommentEditor.class.php b/wcfsetup/install/files/lib/data/comment/CommentEditor.class.php
index 0559bb032da..80bada834c0 100644
--- a/wcfsetup/install/files/lib/data/comment/CommentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/comment/CommentEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Comment     create(array $parameters = [])
- * @method      Comment     getDecoratedObject()
  * @mixin       Comment
+ * @extends DatabaseObjectEditor<Comment>
  */
 class CommentEditor extends DatabaseObjectEditor
 {
@@ -25,6 +24,8 @@ class CommentEditor extends DatabaseObjectEditor
 
     /**
      * Updates response ids.
+     *
+     * @return void
      */
     public function updateResponseIDs()
     {
@@ -42,6 +43,8 @@ public function updateResponseIDs()
 
     /**
      * Updates response ids, including disabled ones.
+     *
+     * @return void
      */
     public function updateUnfilteredResponseIDs()
     {
diff --git a/wcfsetup/install/files/lib/data/comment/CommentList.class.php b/wcfsetup/install/files/lib/data/comment/CommentList.class.php
index 1e53085b6f4..efc183db486 100644
--- a/wcfsetup/install/files/lib/data/comment/CommentList.class.php
+++ b/wcfsetup/install/files/lib/data/comment/CommentList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\comment;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -11,11 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment     current()
- * @method  Comment[]   getObjects()
- * @method  Comment|null    getSingleObject()
- * @method  Comment|null    search($objectID)
- * @property    Comment[] $objects
+ * @template-covariant TDatabaseObject of Comment|DatabaseObjectDecorator<Comment> = Comment
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class CommentList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/comment/LikeableComment.class.php b/wcfsetup/install/files/lib/data/comment/LikeableComment.class.php
index c02aa23865f..8308ca0aa25 100644
--- a/wcfsetup/install/files/lib/data/comment/LikeableComment.class.php
+++ b/wcfsetup/install/files/lib/data/comment/LikeableComment.class.php
@@ -17,8 +17,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment     getDecoratedObject()
  * @mixin   Comment
+ * @extends AbstractLikeObject<Comment>
  */
 class LikeableComment extends AbstractLikeObject implements IReactionObject
 {
diff --git a/wcfsetup/install/files/lib/data/comment/LikeableCommentProvider.class.php b/wcfsetup/install/files/lib/data/comment/LikeableCommentProvider.class.php
index 956b9ff1e83..ea729f29c4a 100644
--- a/wcfsetup/install/files/lib/data/comment/LikeableCommentProvider.class.php
+++ b/wcfsetup/install/files/lib/data/comment/LikeableCommentProvider.class.php
@@ -16,8 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LikeableComment     getObjectByID($objectID)
- * @method  LikeableComment[]   getObjectsByIDs(array $objectIDs)
+ * @extends AbstractObjectTypeProvider<LikeableComment>
+ * @implements ILikeObjectTypeProvider<LikeableComment>
  */
 class LikeableCommentProvider extends AbstractObjectTypeProvider implements
     ILikeObjectTypeProvider,
@@ -80,9 +80,9 @@ public function prepare(array $likes)
 
         foreach ($likeData as $objectTypeID => $likes) {
             $objectType = CommentHandler::getInstance()->getObjectType($objectTypeID);
-            if (CommentHandler::getInstance()->getCommentManager($objectType->objectType) instanceof IViewableLikeProvider) {
-                /** @noinspection PhpUndefinedMethodInspection */
-                CommentHandler::getInstance()->getCommentManager($objectType->objectType)->prepare($likes);
+            $commentManager = CommentHandler::getInstance()->getCommentManager($objectType->objectType);
+            if ($commentManager instanceof IViewableLikeProvider) {
+                $commentManager->prepare($likes);
             }
         }
     }
diff --git a/wcfsetup/install/files/lib/data/comment/StructuredComment.class.php b/wcfsetup/install/files/lib/data/comment/StructuredComment.class.php
index 27210acd4c0..fcbc35ffc9d 100644
--- a/wcfsetup/install/files/lib/data/comment/StructuredComment.class.php
+++ b/wcfsetup/install/files/lib/data/comment/StructuredComment.class.php
@@ -14,8 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment     getDecoratedObject()
  * @mixin   Comment
+ * @extends DatabaseObjectDecorator<Comment>
+ * @implements \Iterator<int, StructuredCommentResponse>
  */
 class StructuredComment extends DatabaseObjectDecorator implements \Countable, \Iterator
 {
@@ -110,6 +111,7 @@ public function getLastResponseID(): int
     /**
      * Sets the user's profile.
      *
+     * @return void
      * @deprecated  3.0
      */
     public function setUserProfile(UserProfile $userProfile)
diff --git a/wcfsetup/install/files/lib/data/comment/StructuredCommentList.class.php b/wcfsetup/install/files/lib/data/comment/StructuredCommentList.class.php
index 635f4f2fce2..214449ca548 100644
--- a/wcfsetup/install/files/lib/data/comment/StructuredCommentList.class.php
+++ b/wcfsetup/install/files/lib/data/comment/StructuredCommentList.class.php
@@ -17,11 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StructuredComment       current()
- * @method  StructuredComment[]     getObjects()
- * @method  StructuredComment|null      getSingleObject()
- * @method  StructuredComment|null      search($objectID)
- * @property    StructuredComment[] $objects
+ * @extends CommentList<StructuredComment>
  */
 class StructuredCommentList extends CommentList
 {
@@ -190,7 +186,7 @@ public function readObjects()
     /**
      * Fetches the like data.
      *
-     * @return  LikeObject[][]
+     * @return array{comment: LikeObject[], response?: LikeObject[]}|array{}
      */
     public function getLikeData()
     {
diff --git a/wcfsetup/install/files/lib/data/comment/ViewableComment.class.php b/wcfsetup/install/files/lib/data/comment/ViewableComment.class.php
index d91f8a2cd20..239b802d39a 100644
--- a/wcfsetup/install/files/lib/data/comment/ViewableComment.class.php
+++ b/wcfsetup/install/files/lib/data/comment/ViewableComment.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment     getDecoratedObject()
  * @mixin   Comment
+ * @extends DatabaseObjectDecorator<Comment>
  */
 class ViewableComment extends DatabaseObjectDecorator
 {
diff --git a/wcfsetup/install/files/lib/data/comment/response/CommentResponse.class.php b/wcfsetup/install/files/lib/data/comment/response/CommentResponse.class.php
index a9d64d1fd62..d53e9d29fdd 100644
--- a/wcfsetup/install/files/lib/data/comment/response/CommentResponse.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/CommentResponse.class.php
@@ -134,7 +134,7 @@ public function getComment()
     /**
      * Sets related comment object.
      *
-     * @param Comment $comment
+     * @return void
      */
     public function setComment(Comment $comment)
     {
diff --git a/wcfsetup/install/files/lib/data/comment/response/CommentResponseAction.class.php b/wcfsetup/install/files/lib/data/comment/response/CommentResponseAction.class.php
index e5f0365dcda..627e8d684b0 100644
--- a/wcfsetup/install/files/lib/data/comment/response/CommentResponseAction.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/CommentResponseAction.class.php
@@ -26,9 +26,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse         create()
- * @method  CommentResponseEditor[]     getObjects()
- * @method  CommentResponseEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<CommentResponse, CommentResponseEditor>
  */
 class CommentResponseAction extends AbstractDatabaseObjectAction
 {
@@ -71,13 +69,15 @@ class CommentResponseAction extends AbstractDatabaseObjectAction
 
     /**
      * response object
-     * @var CommentResponse
+     * @var CommentResponseEditor
      * @deprecated 6.1
      */
     protected $response;
 
     /**
      * Validates parameters to load responses for a given comment id.
+     *
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function validateLoadResponses()
@@ -100,7 +100,12 @@ public function validateLoadResponses()
     /**
      * Returns parsed responses for given comment id.
      *
-     * @return  array
+     * @return array{
+     *  commentID: int,
+     *  lastResponseTime: int,
+     *  lastResponseID: int,
+     *  template: string,
+     * }
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function loadResponses()
@@ -165,7 +170,7 @@ public function loadResponses()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function validateBeginEdit()
@@ -182,7 +187,7 @@ public function validateBeginEdit()
     }
 
     /**
-     * @inheritDoc
+     * @return array{actionName: 'beginEdit', template: string}
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function beginEdit()
@@ -201,7 +206,7 @@ public function beginEdit()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function validateSave()
@@ -212,7 +217,7 @@ public function validateSave()
     }
 
     /**
-     * @inheritDoc
+     * @return array{actionName: 'save', message: string}
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     public function save()
@@ -252,6 +257,7 @@ public function save()
     /**
      * Validates message parameter.
      *
+     * @return void
      * @throws      UserInputException
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
@@ -316,6 +322,8 @@ protected function validateObjectType($objectTypeID = null)
 
     /**
      * Sets the list of disallowed bbcodes for comments.
+     *
+     * @return void
      * @deprecated 6.1 see https://docs.woltlab.com/6.1/migration/wsc60/php/#comment-backend
      */
     protected function setDisallowedBBCodes()
diff --git a/wcfsetup/install/files/lib/data/comment/response/CommentResponseEditor.class.php b/wcfsetup/install/files/lib/data/comment/response/CommentResponseEditor.class.php
index 2753895b89c..db2abfb4378 100644
--- a/wcfsetup/install/files/lib/data/comment/response/CommentResponseEditor.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/CommentResponseEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static CommentResponse     create(array $parameters = [])
- * @method      CommentResponse     getDecoratedObject()
  * @mixin       CommentResponse
+ * @extends DatabaseObjectEditor<CommentResponse>
  */
 class CommentResponseEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/comment/response/CommentResponseList.class.php b/wcfsetup/install/files/lib/data/comment/response/CommentResponseList.class.php
index cc691830c23..b8735144abe 100644
--- a/wcfsetup/install/files/lib/data/comment/response/CommentResponseList.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/CommentResponseList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse     current()
- * @method  CommentResponse[]   getObjects()
- * @method  CommentResponse|null    getSingleObject()
- * @method  CommentResponse|null    search($objectID)
- * @property    CommentResponse[] $objects
+ * @extends DatabaseObjectList<CommentResponse>
  */
 class CommentResponseList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponse.class.php b/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponse.class.php
index 186bb2ff05c..9e9598dfa1f 100644
--- a/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponse.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponse.class.php
@@ -18,8 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse     getDecoratedObject()
  * @mixin   CommentResponse
+ * @extends AbstractLikeObject<CommentResponse>
  */
 class LikeableCommentResponse extends AbstractLikeObject implements IReactionObject
 {
diff --git a/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponseProvider.class.php b/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponseProvider.class.php
index 42b7ccd4df4..972d78b8a09 100644
--- a/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponseProvider.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/LikeableCommentResponseProvider.class.php
@@ -18,8 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LikeableCommentResponse     getObjectByID($objectID)
- * @method  LikeableCommentResponse[]   getObjectsByIDs(array $objectIDs)
+ * @extends AbstractObjectTypeProvider<LikeableCommentResponse>
+ * @implements ILikeObjectTypeProvider<LikeableCommentResponse>
  */
 class LikeableCommentResponseProvider extends AbstractObjectTypeProvider implements
     ILikeObjectTypeProvider,
diff --git a/wcfsetup/install/files/lib/data/comment/response/StructuredCommentResponse.class.php b/wcfsetup/install/files/lib/data/comment/response/StructuredCommentResponse.class.php
index 433cb41efd0..4f82add199b 100644
--- a/wcfsetup/install/files/lib/data/comment/response/StructuredCommentResponse.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/StructuredCommentResponse.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse     getDecoratedObject()
  * @mixin   CommentResponse
+ * @extends DatabaseObjectDecorator<CommentResponse>
  */
 class StructuredCommentResponse extends DatabaseObjectDecorator
 {
@@ -44,7 +44,7 @@ class StructuredCommentResponse extends DatabaseObjectDecorator
     /**
      * Sets the user's profile.
      *
-     * @param UserProfile $userProfile
+     * @return void
      * @deprecated  3.0
      */
     public function setUserProfile(UserProfile $userProfile)
@@ -98,6 +98,7 @@ public static function getResponse($responseID)
      * Sets deletable state.
      *
      * @param bool $deletable
+     * @return void
      */
     public function setIsDeletable($deletable)
     {
@@ -108,6 +109,7 @@ public function setIsDeletable($deletable)
      * Sets editable state.
      *
      * @param bool $editable
+     * @return void
      */
     public function setIsEditable($editable)
     {
diff --git a/wcfsetup/install/files/lib/data/comment/response/ViewableCommentResponse.class.php b/wcfsetup/install/files/lib/data/comment/response/ViewableCommentResponse.class.php
index be1e5b2733f..678739de976 100644
--- a/wcfsetup/install/files/lib/data/comment/response/ViewableCommentResponse.class.php
+++ b/wcfsetup/install/files/lib/data/comment/response/ViewableCommentResponse.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse     getDecoratedObject()
  * @mixin   CommentResponse
+ * @extends DatabaseObjectDecorator<CommentResponse>
  */
 class ViewableCommentResponse extends DatabaseObjectDecorator
 {
diff --git a/wcfsetup/install/files/lib/data/condition/Condition.class.php b/wcfsetup/install/files/lib/data/condition/Condition.class.php
index 6bca7549b64..ee07a33bdec 100644
--- a/wcfsetup/install/files/lib/data/condition/Condition.class.php
+++ b/wcfsetup/install/files/lib/data/condition/Condition.class.php
@@ -15,7 +15,7 @@
  * @property-read   int $conditionID        unique id of the condition
  * @property-read   int $objectTypeID       id of the condition object type (of different condition object type definitions)
  * @property-read   int $objectID       id of the conditioned object of the object type represented by `$objectTypeID`
- * @property-read   array $conditionData      array with the condition data with is processed by the condition object type's processor
+ * @property-read   mixed[] $conditionData      array with the condition data with is processed by the condition object type's processor
  */
 class Condition extends DatabaseObject
 {
diff --git a/wcfsetup/install/files/lib/data/condition/ConditionAction.class.php b/wcfsetup/install/files/lib/data/condition/ConditionAction.class.php
index 79bf2ca7bcf..2657569d056 100644
--- a/wcfsetup/install/files/lib/data/condition/ConditionAction.class.php
+++ b/wcfsetup/install/files/lib/data/condition/ConditionAction.class.php
@@ -11,10 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Condition       create()
- * @method  ConditionEditor[]   getObjects()
- * @method  ConditionEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Condition, ConditionEditor>
  */
-class ConditionAction extends AbstractDatabaseObjectAction
-{
-}
+class ConditionAction extends AbstractDatabaseObjectAction {}
diff --git a/wcfsetup/install/files/lib/data/condition/ConditionEditor.class.php b/wcfsetup/install/files/lib/data/condition/ConditionEditor.class.php
index ce7ca9b1b66..e48bfa35d36 100644
--- a/wcfsetup/install/files/lib/data/condition/ConditionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/condition/ConditionEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Condition   create(array $parameters = [])
- * @method      Condition   getDecoratedObject()
  * @mixin       Condition
+ * @extends DatabaseObjectEditor<Condition>
+ * @implements IEditableCachedObject<Condition>
  */
 class ConditionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/condition/ConditionList.class.php b/wcfsetup/install/files/lib/data/condition/ConditionList.class.php
index 4d08b0ffab0..ba7f1c71cf4 100644
--- a/wcfsetup/install/files/lib/data/condition/ConditionList.class.php
+++ b/wcfsetup/install/files/lib/data/condition/ConditionList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Condition       current()
- * @method  Condition[]     getObjects()
- * @method  Condition|null      getSingleObject()
- * @method  Condition|null      search($objectID)
- * @property    Condition[] $objects
+ * @extends DatabaseObjectList<Condition>
  */
-class ConditionList extends DatabaseObjectList
-{
-}
+class ConditionList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentAction.class.php b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentAction.class.php
index ecb7f3921f9..e566df2a534 100644
--- a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentAction.class.php
+++ b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentAction.class.php
@@ -12,8 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method ContactAttachmentEditor[] getObjects()
- * @method ContactAttachmentEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ContactAttachment, ContactAttachmentEditor>
  */
 class ContactAttachmentAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentEditor.class.php b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentEditor.class.php
index 19ac12fa3d7..d84f0e43c93 100644
--- a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentEditor.class.php
@@ -12,9 +12,8 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method static ContactAttachment create(array $parameters = [])
- * @method ContactAttachment getDecoratedObject()
  * @mixin ContactAttachment
+ * @extends DatabaseObjectEditor<ContactAttachment>
  */
 class ContactAttachmentEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentList.class.php b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentList.class.php
index cf21486d003..6d2c36963fa 100644
--- a/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentList.class.php
+++ b/wcfsetup/install/files/lib/data/contact/attachment/ContactAttachmentList.class.php
@@ -12,10 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method ContactAttachment current()
- * @method ContactAttachment[] getObjects()
- * @method ContactAttachment|null search($objectID)
- * @property ContactAttachment[] $objects
+ * @extends DatabaseObjectList<ContactAttachment>
  */
 class ContactAttachmentList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/contact/option/ContactOptionAction.class.php b/wcfsetup/install/files/lib/data/contact/option/ContactOptionAction.class.php
index cf46e0114c0..af03147be92 100644
--- a/wcfsetup/install/files/lib/data/contact/option/ContactOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/contact/option/ContactOptionAction.class.php
@@ -25,9 +25,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
- *
- * @method  ContactOptionEditor[]   getObjects()
- * @method  ContactOptionEditor getSingleObject()
  */
 class ContactOptionAction extends CustomOptionAction implements ISortableAction
 {
@@ -58,6 +55,8 @@ class ContactOptionAction extends CustomOptionAction implements ISortableAction
 
     /**
      * Sends an email to the selected recipient.
+     *
+     * @return void
      */
     public function send()
     {
diff --git a/wcfsetup/install/files/lib/data/contact/option/ContactOptionEditor.class.php b/wcfsetup/install/files/lib/data/contact/option/ContactOptionEditor.class.php
index c4d0ffc36d2..c7a4b70aa2d 100644
--- a/wcfsetup/install/files/lib/data/contact/option/ContactOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/contact/option/ContactOptionEditor.class.php
@@ -14,9 +14,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method static ContactOption   create(array $parameters = [])
- * @method      ContactOption   getDecoratedObject()
  * @mixin       ContactOption
+ * @extends CustomOptionEditor<ContactOption>
+ * @implements IEditableCachedObject<ContactOption>
  */
 class ContactOptionEditor extends CustomOptionEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientAction.class.php b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientAction.class.php
index 1142fa67ff0..9e6d7220c47 100644
--- a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientAction.class.php
+++ b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientAction.class.php
@@ -18,8 +18,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  ContactRecipientEditor[]    getObjects()
- * @method  ContactRecipientEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ContactRecipient, ContactRecipientEditor>
  */
 class ContactRecipientAction extends AbstractDatabaseObjectAction implements ISortableAction, IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientEditor.class.php b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientEditor.class.php
index 5603c3a03d7..67924d103c4 100644
--- a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientEditor.class.php
+++ b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method static ContactRecipient    create(array $parameters = [])
- * @method      ContactRecipient    getDecoratedObject()
  * @mixin       ContactRecipient
+ * @extends DatabaseObjectEditor<ContactRecipient>
  */
 class ContactRecipientEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientList.class.php b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientList.class.php
index cacdef44330..1cf17398e1a 100644
--- a/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientList.class.php
+++ b/wcfsetup/install/files/lib/data/contact/recipient/ContactRecipientList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  ContactRecipient        current()
- * @method  ContactRecipient[]      getObjects()
- * @method  ContactRecipient|null       getSingleObject()
- * @method  ContactRecipient|null       search($objectID)
- * @property    ContactRecipient[] $objects
+ * @extends DatabaseObjectList<ContactRecipient>
  */
 class ContactRecipientList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/core/object/CoreObjectAction.class.php b/wcfsetup/install/files/lib/data/core/object/CoreObjectAction.class.php
index b8c7d136456..561c27587b7 100644
--- a/wcfsetup/install/files/lib/data/core/object/CoreObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/core/object/CoreObjectAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CoreObject      create()
- * @method  CoreObjectEditor[]  getObjects()
- * @method  CoreObjectEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<CoreObject, CoreObjectEditor>
  */
 class CoreObjectAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/core/object/CoreObjectEditor.class.php b/wcfsetup/install/files/lib/data/core/object/CoreObjectEditor.class.php
index 47341dbe44b..6b7d0dc17ad 100644
--- a/wcfsetup/install/files/lib/data/core/object/CoreObjectEditor.class.php
+++ b/wcfsetup/install/files/lib/data/core/object/CoreObjectEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static CoreObject  create(array $parameters = [])
- * @method      CoreObject  getDecoratedObject()
  * @mixin       CoreObject
+ * @extends DatabaseObjectEditor<CoreObject>
  */
 class CoreObjectEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/core/object/CoreObjectList.class.php b/wcfsetup/install/files/lib/data/core/object/CoreObjectList.class.php
index 28b5b50b1a3..6cf653ff2f9 100644
--- a/wcfsetup/install/files/lib/data/core/object/CoreObjectList.class.php
+++ b/wcfsetup/install/files/lib/data/core/object/CoreObjectList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CoreObject      current()
- * @method  CoreObject[]        getObjects()
- * @method  CoreObject|null     getSingleObject()
- * @method  CoreObject|null     search($objectID)
- * @property    CoreObject[] $objects
+ * @extends DatabaseObjectList<CoreObject>
  */
 class CoreObjectList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/cronjob/CronjobAction.class.php b/wcfsetup/install/files/lib/data/cronjob/CronjobAction.class.php
index 493b91b4e88..0e110e422a6 100644
--- a/wcfsetup/install/files/lib/data/cronjob/CronjobAction.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/CronjobAction.class.php
@@ -20,9 +20,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Cronjob         create()
- * @method  CronjobEditor[]     getObjects()
- * @method  CronjobEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Cronjob, CronjobEditor>
  */
 class CronjobAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
@@ -102,6 +100,8 @@ public function validateToggle()
 
     /**
      * Validates the 'execute' action.
+     *
+     * @return void
      */
     public function validateExecute()
     {
@@ -110,6 +110,11 @@ public function validateExecute()
 
     /**
      * Executes cronjobs.
+     *
+     * @return array<int, array{
+     *  time: int,
+     *  formatted: string,
+     * }>
      */
     public function execute()
     {
@@ -217,6 +222,7 @@ public function execute()
     }
 
     /**
+     * @return void
      * @deprecated 6.0 Either use CronjobScheduler::executeCronjobs() directly, or query CronjobPerformAction.
      */
     public function validateExecuteCronjobs()
@@ -225,6 +231,7 @@ public function validateExecuteCronjobs()
     }
 
     /**
+     * @return void
      * @deprecated 6.0 Either use CronjobScheduler::executeCronjobs() directly, or query CronjobPerformAction.
      */
     public function executeCronjobs()
diff --git a/wcfsetup/install/files/lib/data/cronjob/CronjobEditor.class.php b/wcfsetup/install/files/lib/data/cronjob/CronjobEditor.class.php
index e672e0df676..9d17111d049 100644
--- a/wcfsetup/install/files/lib/data/cronjob/CronjobEditor.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/CronjobEditor.class.php
@@ -17,8 +17,9 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Cronjob     getDecoratedObject()
  * @mixin   Cronjob
+ * @extends DatabaseObjectEditor<Cronjob>
+ * @implements IEditableCachedObject<Cronjob>
  */
 class CronjobEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -29,7 +30,6 @@ class CronjobEditor extends DatabaseObjectEditor implements IEditableCachedObjec
 
     /**
      * @inheritDoc
-     * @return  Cronjob
      */
     public static function create(array $parameters = [])
     {
@@ -44,7 +44,6 @@ public static function create(array $parameters = [])
         }
 
         $cronjob = parent::create($parameters);
-        \assert($cronjob instanceof Cronjob);
 
         // save cronjob description
         if (!empty($descriptions)) {
@@ -59,6 +58,7 @@ public static function create(array $parameters = [])
      * Saves the descriptions of the cronjob in language items.
      *
      * @param string[] $descriptions
+     * @return void
      * @since   3.0
      */
     protected function saveDescriptions(array $descriptions)
diff --git a/wcfsetup/install/files/lib/data/cronjob/CronjobList.class.php b/wcfsetup/install/files/lib/data/cronjob/CronjobList.class.php
index 11de1f27089..13d396e7d8e 100644
--- a/wcfsetup/install/files/lib/data/cronjob/CronjobList.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/CronjobList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Cronjob     current()
- * @method  Cronjob[]   getObjects()
- * @method  Cronjob|null    getSingleObject()
- * @method  Cronjob|null    search($objectID)
- * @property    Cronjob[] $objects
+ * @extends DatabaseObjectList<Cronjob>
  */
 class CronjobList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/cronjob/I18nCronjobList.class.php b/wcfsetup/install/files/lib/data/cronjob/I18nCronjobList.class.php
index 56e2ca4d7f8..5c349c1e23c 100644
--- a/wcfsetup/install/files/lib/data/cronjob/I18nCronjobList.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/I18nCronjobList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.3
  *
- * @method  Cronjob     current()
- * @method  Cronjob[]   getObjects()
- * @method  Cronjob|null    getSingleObject()
- * @method  Cronjob|null    search($objectID)
- * @property    Cronjob[] $objects
+ * @extends I18nDatabaseObjectList<Cronjob>
  */
 class I18nCronjobList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogAction.class.php b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogAction.class.php
index b3da9bfe79f..d96c5634a7a 100644
--- a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogAction.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CronjobLog      create()
- * @method  CronjobLogEditor[]  getObjects()
- * @method  CronjobLogEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<CronjobLog, CronjobLogEditor>
  */
 class CronjobLogAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogEditor.class.php b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogEditor.class.php
index a415abf7295..c60a5677d24 100644
--- a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogEditor.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static CronjobLog  create(array $parameters = [])
- * @method      CronjobLog  getDecoratedObject()
  * @mixin       CronjobLog
+ * @extends DatabaseObjectEditor<CronjobLog>
  */
 class CronjobLogEditor extends DatabaseObjectEditor
 {
@@ -25,6 +24,8 @@ class CronjobLogEditor extends DatabaseObjectEditor
 
     /**
      * Deletes all cronjob logs.
+     *
+     * @return void
      */
     public static function clearLogs()
     {
diff --git a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogList.class.php b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogList.class.php
index fc82e184f5b..126387278a6 100644
--- a/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogList.class.php
+++ b/wcfsetup/install/files/lib/data/cronjob/log/CronjobLogList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CronjobLog      current()
- * @method  CronjobLog[]        getObjects()
- * @method  CronjobLog|null     getSingleObject()
- * @method  CronjobLog|null     search($objectID)
- * @property    CronjobLog[] $objects
+ * @extends DatabaseObjectList<CronjobLog>
  */
 class CronjobLogList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/custom/option/CustomOption.class.php b/wcfsetup/install/files/lib/data/custom/option/CustomOption.class.php
index d3ed4035b34..3b7328f7aeb 100644
--- a/wcfsetup/install/files/lib/data/custom/option/CustomOption.class.php
+++ b/wcfsetup/install/files/lib/data/custom/option/CustomOption.class.php
@@ -106,6 +106,7 @@ public function getOptionValue()
      * Sets the value of this option.
      *
      * @param string $value
+     * @return void
      */
     public function setOptionValue($value)
     {
diff --git a/wcfsetup/install/files/lib/data/custom/option/CustomOptionAction.class.php b/wcfsetup/install/files/lib/data/custom/option/CustomOptionAction.class.php
index 15db263a1f4..bbd38816e65 100644
--- a/wcfsetup/install/files/lib/data/custom/option/CustomOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/custom/option/CustomOptionAction.class.php
@@ -14,9 +14,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  CustomOption        create()
- * @method  CustomOptionEditor[]    getObjects()
- * @method  CustomOptionEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<CustomOption, CustomOptionEditor>
  */
 abstract class CustomOptionAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/custom/option/CustomOptionEditor.class.php b/wcfsetup/install/files/lib/data/custom/option/CustomOptionEditor.class.php
index 6b53e75dd5d..46d7f91221f 100644
--- a/wcfsetup/install/files/lib/data/custom/option/CustomOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/custom/option/CustomOptionEditor.class.php
@@ -12,9 +12,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method static CustomOption    create(array $parameters = [])
- * @method      CustomOption    getDecoratedObject()
  * @mixin       CustomOption
+ * @template TCustomOption of CustomOption = CustomOption
+ * @extends DatabaseObjectEditor<TCustomOption>
  */
 abstract class CustomOptionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/custom/option/CustomOptionList.class.php b/wcfsetup/install/files/lib/data/custom/option/CustomOptionList.class.php
index d090e0b8111..30345774e72 100644
--- a/wcfsetup/install/files/lib/data/custom/option/CustomOptionList.class.php
+++ b/wcfsetup/install/files/lib/data/custom/option/CustomOptionList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  CustomOption        current()
- * @method  CustomOption[]      getObjects()
- * @method  CustomOption|null   getSingleObject()
- * @method  CustomOption|null   search($objectID)
- * @property    CustomOption[] $objects
+ * @extends DatabaseObjectList<CustomOption>
  */
 abstract class CustomOptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
index a131377042a..d9bcd8c90ae 100644
--- a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
@@ -17,8 +17,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
  *
- * @method  DevtoolsMissingLanguageItemEditor[] getObjects()
- * @method  DevtoolsMissingLanguageItemEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<DevtoolsMissingLanguageItem, DevtoolsMissingLanguageItemEditor>
  */
 class DevtoolsMissingLanguageItemAction extends AbstractDatabaseObjectAction implements IDeleteAction
 {
@@ -29,6 +28,8 @@ class DevtoolsMissingLanguageItemAction extends AbstractDatabaseObjectAction imp
 
     /**
      * Logs a missing language item.
+     *
+     * @return void
      */
     public function logLanguageItem()
     {
@@ -102,6 +103,8 @@ public function validateDelete()
 
     /**
      * Validates the `clearLog` action.
+     *
+     * @return void
      */
     public function validateClearLog()
     {
@@ -114,6 +117,8 @@ public function validateClearLog()
 
     /**
      * Removes all entries from the missing language item log.
+     *
+     * @return void
      */
     public function clearLog()
     {
diff --git a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemEditor.class.php b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemEditor.class.php
index ea06a64ad9b..a74be57ccbf 100644
--- a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
  *
- * @method static DevtoolsMissingLanguageItem create(array $parameters = [])
- * @method      DevtoolsMissingLanguageItem getDecoratedObject()
  * @mixin       DevtoolsMissingLanguageItem
+ * @extends DatabaseObjectEditor<DevtoolsMissingLanguageItem>
  */
 class DevtoolsMissingLanguageItemEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemList.class.php b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemList.class.php
index 10837005cd8..00693640bc4 100644
--- a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemList.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
  *
- * @method  DevtoolsMissingLanguageItem     current()
- * @method  DevtoolsMissingLanguageItem[]       getObjects()
- * @method  DevtoolsMissingLanguageItem|null    getSingleObject()
- * @method  DevtoolsMissingLanguageItem|null    search($objectID)
- * @property    DevtoolsMissingLanguageItem[] $objects
+ * @extends DatabaseObjectList<DevtoolsMissingLanguageItem>
  */
 class DevtoolsMissingLanguageItemList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProject.class.php b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProject.class.php
index 821dd98ca51..55d42426afd 100644
--- a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProject.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProject.class.php
@@ -106,7 +106,7 @@ public function validate($pathOnly = false)
     /**
      * Returns true if this project appears to be `WoltLab Suite Core`.
      *
-     * @return      bool
+     * @return bool
      */
     public function isCore()
     {
@@ -225,7 +225,7 @@ public function getLanguageFiles()
     /**
      * Sets the package that belongs to this project.
      *
-     * @param Package $package
+     * @return void
      * @throws  \InvalidArgumentException   if the identifier of the given package does not match
      * @since   5.2
      */
@@ -272,7 +272,7 @@ public static function validatePath($path)
      * Returns true if the path appears to point to `WoltLab Suite Core`.
      *
      * @param string $path
-     * @return      bool
+     * @return bool
      */
     public static function pathIsCore($path)
     {
diff --git a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectAction.class.php b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectAction.class.php
index c9f75bf66a6..c5b5716be31 100644
--- a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectAction.class.php
@@ -20,8 +20,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  DevtoolsProjectEditor[] getObjects()
- * @method  DevtoolsProjectEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<DevtoolsProject, DevtoolsProjectEditor>
  */
 class DevtoolsProjectAction extends AbstractDatabaseObjectAction
 {
@@ -56,14 +55,12 @@ class DevtoolsProjectAction extends AbstractDatabaseObjectAction
 
     /**
      * @inheritDoc
-     * @return  DevtoolsProject
      * @since   5.2
      */
     public function create()
     {
         $this->parameters['data']['path'] = FileUtil::addTrailingSlash($this->parameters['data']['path']);
 
-        /** @var DevtoolsProject $project */
         $project = parent::create();
 
         // ensure that the project directory exists
@@ -87,6 +84,7 @@ public function validateDelete()
     /**
      * Validates the 'quickSetup' action.
      *
+     * @return void
      * @throws  IllegalLinkException
      */
     public function validateQuickSetup()
@@ -103,7 +101,12 @@ public function validateQuickSetup()
     /**
      * Quickly setups multiple projects by scanning a directory.
      *
-     * @return  array
+     * @return array{
+     *  successMessage: string,
+     * }|array{
+     *  errorMessage: string,
+     *  errorType: string,
+     * }
      */
     public function quickSetup()
     {
@@ -182,6 +185,7 @@ public function quickSetup()
     /**
      * Checks if the `installPackage` action can be executed.
      *
+     * @return void
      * @throws  IllegalLinkException
      * @since   5.2
      */
@@ -199,8 +203,8 @@ public function validateInstallPackage()
     /**
      * Installs a package that is currently only available as a project.
      *
-     * @return  int[]       id of the package installation queue for the
-     * @since   5.2
+     * @return array{isApplication: int, queueID: int}
+     * @since 5.2
      */
     public function installPackage()
     {
@@ -227,6 +231,7 @@ public function installPackage()
     /**
      * Checks if the `deletePipEntry` action can be executed.
      *
+     * @return void
      * @throws  IllegalLinkException
      * @since   5.2
      */
diff --git a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectEditor.class.php b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectEditor.class.php
index c3902d41104..fdb819fe150 100644
--- a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectEditor.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method static DevtoolsProject create(array $parameters = [])
- * @method      DevtoolsProject getDecoratedObject()
  * @mixin       DevtoolsProject
+ * @extends DatabaseObjectEditor<DevtoolsProject>
  */
 class DevtoolsProjectEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectList.class.php b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectList.class.php
index 06661821886..371afeb69c0 100644
--- a/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectList.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/project/DevtoolsProjectList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  DevtoolsProject     current()
- * @method  DevtoolsProject[]   getObjects()
- * @method  DevtoolsProject|null    getSingleObject()
- * @method  DevtoolsProject|null    search($objectID)
- * @property    DevtoolsProject[] $objects
+ * @extends DatabaseObjectList<DevtoolsProject>
  */
 class DevtoolsProjectList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntry.class.php b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntry.class.php
index 34af381bc81..32f0b7b2781 100644
--- a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntry.class.php
+++ b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntry.class.php
@@ -4,6 +4,7 @@
 
 use wcf\data\DatabaseObject;
 use wcf\data\object\type\ObjectTypeCache;
+use wcf\system\edit\IHistorySavingObject;
 
 /**
  * Represents an edit history entry.
@@ -26,14 +27,14 @@
 class EditHistoryEntry extends DatabaseObject
 {
     /**
-     * @inheritDoc
+     * @var ?IHistorySavingObject
      */
     protected $object;
 
     /**
      * Returns the message text of the history entry.
      *
-     * @return  string
+     * @return string
      */
     public function getMessage()
     {
@@ -43,7 +44,7 @@ public function getMessage()
     /**
      * Returns the corresponding IHistorySavingObject
      *
-     * @return  \wcf\system\edit\IHistorySavingObject
+     * @return IHistorySavingObject
      */
     public function getObject()
     {
diff --git a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryAction.class.php b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryAction.class.php
index 313d450e599..54e7a093c16 100644
--- a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryAction.class.php
+++ b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryAction.class.php
@@ -13,9 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EditHistoryEntry        create()
- * @method  EditHistoryEntryEditor[]    getObjects()
- * @method  EditHistoryEntryEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<EditHistoryEntry, EditHistoryEntryEditor>
  */
 class EditHistoryEntryAction extends AbstractDatabaseObjectAction
 {
@@ -26,6 +24,8 @@ class EditHistoryEntryAction extends AbstractDatabaseObjectAction
 
     /**
      * Checks permissions to revert.
+     *
+     * @return void
      */
     public function validateRevert()
     {
@@ -43,6 +43,8 @@ public function validateRevert()
 
     /**
      * Reverts the objects back to this history entry.
+     *
+     * @return void
      */
     public function revert()
     {
diff --git a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryEditor.class.php b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryEditor.class.php
index b55b90930ff..c1c445166b5 100644
--- a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static EditHistoryEntry    create(array $parameters = [])
- * @method      EditHistoryEntry    getDecoratedObject()
  * @mixin       EditHistoryEntry
+ * @extends DatabaseObjectEditor<EditHistoryEntry>
  */
 class EditHistoryEntryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryList.class.php b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryList.class.php
index 6c84822dddc..6c19b31c6ff 100644
--- a/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryList.class.php
+++ b/wcfsetup/install/files/lib/data/edit/history/entry/EditHistoryEntryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EditHistoryEntry        current()
- * @method  EditHistoryEntry[]      getObjects()
- * @method  EditHistoryEntry|null       getSingleObject()
- * @method  EditHistoryEntry|null       search($objectID)
- * @property    EditHistoryEntry[] $objects
+ * @extends DatabaseObjectList<EditHistoryEntry>
  */
 class EditHistoryEntryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryAction.class.php b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryAction.class.php
index d7b39e25947..b48048b23c2 100644
--- a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryAction.class.php
+++ b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryAction.class.php
@@ -12,9 +12,7 @@
  * @copyright   2001-2021 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EmailLogEntry        create()
- * @method  EmailLogEntryEditor[]    getObjects()
- * @method  EmailLogEntryEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<EmailLogEntry, EmailLogEntryEditor>
  */
 class EmailLogEntryAction extends AbstractDatabaseObjectAction
 {
@@ -25,6 +23,8 @@ class EmailLogEntryAction extends AbstractDatabaseObjectAction
 
     /**
      * Deletes old log entries.
+     *
+     * @return void
      */
     public function prune()
     {
diff --git a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryEditor.class.php b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryEditor.class.php
index d5daf5bf6fc..cd1d8b4aab5 100644
--- a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2021 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static EmailLogEntry    create(array $parameters = [])
- * @method      EmailLogEntry    getDecoratedObject()
  * @mixin       EmailLogEntry
+ * @extends DatabaseObjectEditor<EmailLogEntry>
  */
 class EmailLogEntryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryList.class.php b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryList.class.php
index 320ac129af5..d60bd2b28be 100644
--- a/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryList.class.php
+++ b/wcfsetup/install/files/lib/data/email/log/entry/EmailLogEntryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2021 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EmailLogEntry        current()
- * @method  EmailLogEntry[]      getObjects()
- * @method  EmailLogEntry|null       getSingleObject()
- * @method  EmailLogEntry|null       search($objectID)
- * @property    EmailLogEntry[] $objects
+ * @extends DatabaseObjectList<EmailLogEntry>
  */
 class EmailLogEntryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/event/listener/EventListenerAction.class.php b/wcfsetup/install/files/lib/data/event/listener/EventListenerAction.class.php
index 7b8de8a61d8..97abd4dc8a1 100644
--- a/wcfsetup/install/files/lib/data/event/listener/EventListenerAction.class.php
+++ b/wcfsetup/install/files/lib/data/event/listener/EventListenerAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EventListener       create()
- * @method  EventListenerEditor[]   getObjects()
- * @method  EventListenerEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<EventListener, EventListenerEditor>
  */
 class EventListenerAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/event/listener/EventListenerEditor.class.php b/wcfsetup/install/files/lib/data/event/listener/EventListenerEditor.class.php
index 7e416a9ce05..996075d264b 100644
--- a/wcfsetup/install/files/lib/data/event/listener/EventListenerEditor.class.php
+++ b/wcfsetup/install/files/lib/data/event/listener/EventListenerEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static EventListener   create(array $parameters = [])
- * @method      EventListener   getDecoratedObject()
  * @mixin       EventListener
+ * @extends DatabaseObjectEditor<EventListener>
+ * @implements IEditableCachedObject<EventListener>
  */
 class EventListenerEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/event/listener/EventListenerList.class.php b/wcfsetup/install/files/lib/data/event/listener/EventListenerList.class.php
index a49db59002b..e6bd48d1ef4 100644
--- a/wcfsetup/install/files/lib/data/event/listener/EventListenerList.class.php
+++ b/wcfsetup/install/files/lib/data/event/listener/EventListenerList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  EventListener       current()
- * @method  EventListener[]     getObjects()
- * @method  EventListener|null  getSingleObject()
- * @method  EventListener|null  search($objectID)
- * @property    EventListener[] $objects
+ * @extends DatabaseObjectList<EventListener>
  */
 class EventListenerList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/file/File.class.php b/wcfsetup/install/files/lib/data/file/File.class.php
index 3087422e875..b72e116f27c 100644
--- a/wcfsetup/install/files/lib/data/file/File.class.php
+++ b/wcfsetup/install/files/lib/data/file/File.class.php
@@ -189,6 +189,9 @@ public function getThumbnails(): array
         return $this->thumbnails;
     }
 
+    /**
+     * @param ?mixed[] $metaData
+     */
     public function toHtmlElement(?array $metaData = null): string
     {
         $thumbnails = [];
diff --git a/wcfsetup/install/files/lib/data/file/FileAction.class.php b/wcfsetup/install/files/lib/data/file/FileAction.class.php
index 001bcb064a1..7fca3e2c933 100644
--- a/wcfsetup/install/files/lib/data/file/FileAction.class.php
+++ b/wcfsetup/install/files/lib/data/file/FileAction.class.php
@@ -10,9 +10,7 @@
  * @copyright 2001-2023 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method File create()
- * @method FileEditor[] getObjects()
- * @method FileEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<File, FileEditor>
  */
 class FileAction extends AbstractDatabaseObjectAction
 {
@@ -26,7 +24,12 @@ public function delete()
         }
 
         if ($this->objects !== []) {
-            FileProcessor::getInstance()->delete($this->objects);
+            FileProcessor::getInstance()->delete(
+                \array_map(
+                    static fn(FileEditor $editor) => $editor->getDecoratedObject(),
+                    $this->objects
+                )
+            );
         }
 
         return parent::delete();
diff --git a/wcfsetup/install/files/lib/data/file/FileEditor.class.php b/wcfsetup/install/files/lib/data/file/FileEditor.class.php
index 5ae0dde3472..d7cd358fb32 100644
--- a/wcfsetup/install/files/lib/data/file/FileEditor.class.php
+++ b/wcfsetup/install/files/lib/data/file/FileEditor.class.php
@@ -16,9 +16,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method static File create(array $parameters = [])
- * @method File getDecoratedObject()
  * @mixin File
+ * @extends DatabaseObjectEditor<File>
  */
 class FileEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/file/FileList.class.php b/wcfsetup/install/files/lib/data/file/FileList.class.php
index 22b16c0a776..df756fbad9b 100644
--- a/wcfsetup/install/files/lib/data/file/FileList.class.php
+++ b/wcfsetup/install/files/lib/data/file/FileList.class.php
@@ -10,11 +10,7 @@
  * @copyright 2001-2023 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method File current()
- * @method File[] getObjects()
- * @method File|null getSingleObject()
- * @method File|null search($objectID)
- * @property File[] $objects
+ * @extends DatabaseObjectList<File>
  */
 class FileList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php b/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
index bd0fc030fca..35161f33829 100644
--- a/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
+++ b/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
@@ -74,6 +74,9 @@ public function getPathname(): string
         return $this->getPath() . $this->getFilename();
     }
 
+    /**
+     * @return mixed[]
+     */
     public function getContext(): array
     {
         return JSON::decode($this->context);
diff --git a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryAction.class.php b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryAction.class.php
index 8fbb72adb6a..f7d47c3d5e1 100644
--- a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryAction.class.php
+++ b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryAction.class.php
@@ -10,9 +10,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method FileTemporary create()
- * @method FileTemporaryEditor[] getObjects()
- * @method FileTemporaryEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<FileTemporary, FileTemporaryEditor>
  */
 class FileTemporaryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryEditor.class.php b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryEditor.class.php
index 7148784ee5b..3ce0b8a3566 100644
--- a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryEditor.class.php
@@ -10,9 +10,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method static FileTemporary create(array $parameters = [])
- * @method FileTemporary getDecoratedObject()
  * @mixin FileTemporary
+ * @extends DatabaseObjectEditor<FileTemporary>
  */
 class FileTemporaryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryList.class.php b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryList.class.php
index fe6c3a835c7..46a3d9d4031 100644
--- a/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryList.class.php
+++ b/wcfsetup/install/files/lib/data/file/temporary/FileTemporaryList.class.php
@@ -10,11 +10,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method FileTemporary current()
- * @method FileTemporary[] getObjects()
- * @method FileTemporary|null getSingleObject()
- * @method FileTemporary|null search($objectID)
- * @property FileTemporary[] $objects
+ * @extends DatabaseObjectList<FileTemporary>
  */
 class FileTemporaryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailAction.class.php b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailAction.class.php
index f502b2e746d..19573512c19 100644
--- a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailAction.class.php
+++ b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailAction.class.php
@@ -10,9 +10,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method FileThumbnail create()
- * @method FileThumbnailEditor[] getObjects()
- * @method FileThumbnailEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<FileThumbnail, FileThumbnailEditor>
  */
 class FileThumbnailAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailEditor.class.php b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailEditor.class.php
index c94b5b6caf3..187c1575755 100644
--- a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailEditor.class.php
+++ b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method static FileThumbnail create(array $parameters = [])
- * @method FileThumbnail getDecoratedObject()
  * @mixin FileThumbnail
+ * @extends DatabaseObjectEditor<FileThumbnail>
  */
 class FileThumbnailEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailList.class.php b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailList.class.php
index 05813ea3535..0c407a920a7 100644
--- a/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailList.class.php
+++ b/wcfsetup/install/files/lib/data/file/thumbnail/FileThumbnailList.class.php
@@ -10,11 +10,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method FileThumbnail current()
- * @method FileThumbnail[] getObjects()
- * @method FileThumbnail|null getSingleObject()
- * @method FileThumbnail|null search($objectID)
- * @property FileThumbnail[] $objects
+ * @extends DatabaseObjectList<FileThumbnail>
  */
 class FileThumbnailList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/label/LabelAction.class.php b/wcfsetup/install/files/lib/data/label/LabelAction.class.php
index 3460a4ab504..c635cf23ef8 100644
--- a/wcfsetup/install/files/lib/data/label/LabelAction.class.php
+++ b/wcfsetup/install/files/lib/data/label/LabelAction.class.php
@@ -16,8 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LabelEditor[]   getObjects()
- * @method  LabelEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Label, LabelEditor>
  */
 class LabelAction extends AbstractDatabaseObjectAction implements ISortableAction
 {
@@ -165,6 +164,9 @@ public function updatePosition()
         WCF::getDB()->commitTransaction();
     }
 
+    /**
+     * @return array<string, string>
+     */
     #[\Override]
     public function getI18nSaveTypes(): array
     {
diff --git a/wcfsetup/install/files/lib/data/label/LabelEditor.class.php b/wcfsetup/install/files/lib/data/label/LabelEditor.class.php
index a656591e9f1..17eb8cf50fb 100644
--- a/wcfsetup/install/files/lib/data/label/LabelEditor.class.php
+++ b/wcfsetup/install/files/lib/data/label/LabelEditor.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Label   create(array $parameters = [])
- * @method      Label   getDecoratedObject()
  * @mixin       Label
+ * @extends DatabaseObjectEditor<Label>
+ * @implements IEditableCachedObject<Label>
  */
 class LabelEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -38,6 +38,7 @@ public static function resetCache()
      *
      * @param int $groupID
      * @param int $showOrder
+     * @return void
      */
     public function setShowOrder($groupID, $showOrder = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/label/LabelList.class.php b/wcfsetup/install/files/lib/data/label/LabelList.class.php
index 0e35d18549e..206120b58a4 100644
--- a/wcfsetup/install/files/lib/data/label/LabelList.class.php
+++ b/wcfsetup/install/files/lib/data/label/LabelList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Label       current()
- * @method  Label[]     getObjects()
- * @method  Label|null  getSingleObject()
- * @method  Label|null  search($objectID)
- * @property    Label[] $objects
+ * @extends DatabaseObjectList<Label>
  */
 class LabelList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/label/group/I18nLabelGroupList.class.php b/wcfsetup/install/files/lib/data/label/group/I18nLabelGroupList.class.php
index 86181a5867e..8274780d436 100644
--- a/wcfsetup/install/files/lib/data/label/group/I18nLabelGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/label/group/I18nLabelGroupList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method      LabelGroup        current()
- * @method      LabelGroup[]      getObjects()
- * @method      LabelGroup|null   getSingleObject()
- * @method      LabelGroup|null   search($objectID)
- * @property    LabelGroup[] $objects
+ * @extends I18nDatabaseObjectList<LabelGroup>
  */
 class I18nLabelGroupList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/label/group/LabelGroupAction.class.php b/wcfsetup/install/files/lib/data/label/group/LabelGroupAction.class.php
index 8aa8a474a81..a0fbadd459a 100644
--- a/wcfsetup/install/files/lib/data/label/group/LabelGroupAction.class.php
+++ b/wcfsetup/install/files/lib/data/label/group/LabelGroupAction.class.php
@@ -16,9 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LabelGroup      create()
- * @method  LabelGroupEditor[]  getObjects()
- * @method  LabelGroupEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<LabelGroup, LabelGroupEditor>
  */
 class LabelGroupAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/label/group/LabelGroupEditor.class.php b/wcfsetup/install/files/lib/data/label/group/LabelGroupEditor.class.php
index fc4c1ca082b..f90f1499be4 100644
--- a/wcfsetup/install/files/lib/data/label/group/LabelGroupEditor.class.php
+++ b/wcfsetup/install/files/lib/data/label/group/LabelGroupEditor.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static LabelGroup  create(array $parameters = [])
- * @method      LabelGroup  getDecoratedObject()
  * @mixin       LabelGroup
+ * @extends DatabaseObjectEditor<LabelGroup>
+ * @implements IEditableCachedObject<LabelGroup>
  */
 class LabelGroupEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/label/group/LabelGroupList.class.php b/wcfsetup/install/files/lib/data/label/group/LabelGroupList.class.php
index 5bd43fc1b3f..e4444c79082 100644
--- a/wcfsetup/install/files/lib/data/label/group/LabelGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/label/group/LabelGroupList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LabelGroup      current()
- * @method  LabelGroup[]        getObjects()
- * @method  LabelGroup|null     getSingleObject()
- * @method  LabelGroup|null     search($objectID)
- * @property    LabelGroup[] $objects
+ * @extends DatabaseObjectList<LabelGroup>
  */
 class LabelGroupList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/label/group/ViewableLabelGroup.class.php b/wcfsetup/install/files/lib/data/label/group/ViewableLabelGroup.class.php
index 0dc95b2f38d..8d2bbfbd749 100644
--- a/wcfsetup/install/files/lib/data/label/group/ViewableLabelGroup.class.php
+++ b/wcfsetup/install/files/lib/data/label/group/ViewableLabelGroup.class.php
@@ -16,8 +16,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LabelGroup  getDecoratedObject()
  * @mixin   LabelGroup
+ * @extends DatabaseObjectDecorator<LabelGroup>
+ * @implements ITraversableObject<Label>
  */
 class ViewableLabelGroup extends DatabaseObjectDecorator implements \Countable, ITraversableObject
 {
@@ -56,7 +57,7 @@ class ViewableLabelGroup extends DatabaseObjectDecorator implements \Countable,
     /**
      * Adds a label.
      *
-     * @param Label $label
+     * @return void
      */
     public function addLabel(Label $label)
     {
@@ -67,7 +68,8 @@ public function addLabel(Label $label)
     /**
      * Sets group permissions.
      *
-     * @param array $permissions
+     * @param mixed[] $permissions
+     * @return void
      */
     public function setGroupPermissions(array $permissions)
     {
@@ -77,7 +79,8 @@ public function setGroupPermissions(array $permissions)
     /**
      * Sets user permissions.
      *
-     * @param array $permissions
+     * @param mixed[] $permissions
+     * @return void
      */
     public function setUserPermissions(array $permissions)
     {
@@ -139,7 +142,7 @@ public function getPermission($optionID, ?User $user = null)
     /**
      * Returns a list of label ids.
      *
-     * @return  int[]
+     * @return int[]
      */
     public function getLabelIDs()
     {
@@ -149,7 +152,7 @@ public function getLabelIDs()
     /**
      * Returns a list of labels.
      *
-     * @return  Label[]
+     * @return Label[]
      */
     public function getLabels()
     {
@@ -160,7 +163,7 @@ public function getLabels()
      * Returns a label by id.
      *
      * @param int $labelID
-     * @return  Label|null
+     * @return ?Label
      */
     public function getLabel($labelID)
     {
diff --git a/wcfsetup/install/files/lib/data/language/Language.class.php b/wcfsetup/install/files/lib/data/language/Language.class.php
index 2250cc55072..df6afa41ffa 100644
--- a/wcfsetup/install/files/lib/data/language/Language.class.php
+++ b/wcfsetup/install/files/lib/data/language/Language.class.php
@@ -128,6 +128,8 @@ public function get(string $item, bool $optional = false): string
 
     /**
      * Executes template scripting in a language variable.
+     *
+     * @param array<string, mixed> $variables
      */
     public function getDynamicVariable(string $item, array $variables = [], bool $optional = false): string
     {
diff --git a/wcfsetup/install/files/lib/data/language/LanguageAction.class.php b/wcfsetup/install/files/lib/data/language/LanguageAction.class.php
index cef2911d27e..8896243dc86 100644
--- a/wcfsetup/install/files/lib/data/language/LanguageAction.class.php
+++ b/wcfsetup/install/files/lib/data/language/LanguageAction.class.php
@@ -17,8 +17,7 @@
  * @copyright   2001-2023 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LanguageEditor[]    getObjects()
- * @method  LanguageEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Language, LanguageEditor>
  */
 class LanguageAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
@@ -57,12 +56,10 @@ class LanguageAction extends AbstractDatabaseObjectAction implements IToggleActi
 
     /**
      * @inheritDoc
-     * @return  Language
      */
     public function create()
     {
         $object = parent::create();
-        \assert($object instanceof Language);
 
         if (isset($this->parameters['sourceLanguageID']) && $this->parameters['sourceLanguageID']) {
             $sourceLanguage = LanguageFactory::getInstance()->getLanguage($this->parameters['sourceLanguageID']);
@@ -80,6 +77,8 @@ public function create()
 
     /**
      * Validates permission to set a language as default.
+     *
+     * @return void
      */
     public function validateSetAsDefault()
     {
@@ -90,6 +89,8 @@ public function validateSetAsDefault()
 
     /**
      * Sets language as default
+     *
+     * @return void
      */
     public function setAsDefault()
     {
diff --git a/wcfsetup/install/files/lib/data/language/LanguageEditor.class.php b/wcfsetup/install/files/lib/data/language/LanguageEditor.class.php
index fc968cebb35..02c077df45e 100644
--- a/wcfsetup/install/files/lib/data/language/LanguageEditor.class.php
+++ b/wcfsetup/install/files/lib/data/language/LanguageEditor.class.php
@@ -30,9 +30,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Language    create(array $parameters = [])
- * @method      Language    getDecoratedObject()
  * @mixin       Language
+ * @extends DatabaseObjectEditor<Language>
+ * @implements IEditableCachedObject<Language>
  */
 class LanguageEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -54,7 +54,7 @@ public function delete()
     /**
      * Updates the language files for the given category.
      *
-     * @param LanguageCategory $languageCategory
+     * @return void
      */
     public function updateCategory(LanguageCategory $languageCategory)
     {
@@ -65,6 +65,7 @@ public function updateCategory(LanguageCategory $languageCategory)
      * Write the languages files.
      *
      * @param int[] $languageCategoryIDs
+     * @return void
      */
     protected function writeLanguageFiles(array $languageCategoryIDs)
     {
@@ -125,6 +126,8 @@ protected function writeLanguageFiles(array $languageCategoryIDs)
 
     /**
      * Exports this language.
+     *
+     * @return void
      */
     public function export(int $packageID, bool $exportCustomValues = false)
     {
@@ -310,10 +313,10 @@ protected function validateXMLStructure(XML $xml): void
      * Imports language items from an XML file into this language.
      * Updates the relevant language files automatically.
      *
-     * @param XML $xml
      * @param int $packageID
      * @param bool $updateFiles
      * @param bool $updateExistingItems
+     * @return void
      * @throws  \InvalidArgumentException   if given XML file is invalid
      */
     public function updateFromXML(XML $xml, $packageID, $updateFiles = true, $updateExistingItems = true)
@@ -691,6 +694,7 @@ final public static function validateItemName(string $itemName, string $category
      *
      * @param string $languageID
      * @param string $category
+     * @return void
      */
     public static function deleteLanguageFiles($languageID = '.*', $category = '.*')
     {
@@ -706,6 +710,8 @@ public static function deleteLanguageFiles($languageID = '.*', $category = '.*')
 
     /**
      * Deletes relevant template compilations.
+     *
+     * @return void
      */
     public function deleteCompiledTemplates()
     {
@@ -717,6 +723,8 @@ public function deleteCompiledTemplates()
 
     /**
      * Updates all language files of the given package id.
+     *
+     * @return void
      */
     public static function updateAll()
     {
@@ -726,9 +734,8 @@ public static function updateAll()
     /**
      * Takes an XML object and returns the specific language code.
      *
-     * @param XML $xml
-     * @return  string
-     * @throws  SystemException
+     * @return string
+     * @throws SystemException
      */
     public static function readLanguageCodeFromXML(XML $xml)
     {
@@ -747,9 +754,8 @@ public static function readLanguageCodeFromXML(XML $xml)
     /**
      * Takes an XML object and returns the specific language name.
      *
-     * @param XML $xml
-     * @return  string      language name
-     * @throws  SystemException
+     * @return string language name
+     * @throws SystemException
      */
     public static function readLanguageNameFromXML(XML $xml)
     {
@@ -768,9 +774,8 @@ public static function readLanguageNameFromXML(XML $xml)
     /**
      * Takes an XML object and returns the specific country code.
      *
-     * @param XML $xml
-     * @return  string      country code
-     * @throws  SystemException
+     * @return string country code
+     * @throws SystemException
      */
     public static function readCountryCodeFromXML(XML $xml)
     {
@@ -790,10 +795,8 @@ public static function readCountryCodeFromXML(XML $xml)
      * Imports language items from an XML file into a new or a current language.
      * Updates the relevant language files automatically.
      *
-     * @param XML $xml
      * @param int $packageID
-     * @param Language $source
-     * @return  LanguageEditor
+     * @return LanguageEditor
      */
     public static function importFromXML(XML $xml, $packageID, ?Language $source = null)
     {
@@ -836,6 +839,7 @@ public static function importFromXML(XML $xml, $packageID, ?Language $source = n
      * Caution: This method expects that target language does not have any items!
      *
      * @param Language $destination
+     * @return void
      */
     public function copy(Language $destination)
     {
@@ -854,10 +858,11 @@ public function copy(Language $destination)
     /**
      * Updates the language items of a language category.
      *
-     * @param array $items
+     * @param array<string, string> $items
      * @param LanguageCategory $category
      * @param int $packageID
-     * @param array $useCustom
+     * @param array<int, int> $useCustom
+     * @return void
      */
     public function updateItems(
         array $items,
@@ -915,6 +920,8 @@ public function updateItems(
 
     /**
      * Sets current language as default language.
+     *
+     * @return void
      */
     public function setAsDefault()
     {
@@ -932,6 +939,8 @@ public function setAsDefault()
 
     /**
      * Clears language cache.
+     *
+     * @return void
      */
     public function clearCache()
     {
@@ -941,7 +950,8 @@ public function clearCache()
     /**
      * Enables the multilingualism feature for given languages.
      *
-     * @param array $languageIDs
+     * @param int[] $languageIDs
+     * @return void
      */
     public static function enableMultilingualism(array $languageIDs = [])
     {
@@ -983,6 +993,7 @@ public static function resetCache()
      *
      * @param int $sourceLanguageID
      * @param int $destinationLanguageID
+     * @return void
      */
     public static function copyLanguageContent($sourceLanguageID, $destinationLanguageID)
     {
diff --git a/wcfsetup/install/files/lib/data/language/LanguageList.class.php b/wcfsetup/install/files/lib/data/language/LanguageList.class.php
index ef15b21c0da..cf247b1d982 100644
--- a/wcfsetup/install/files/lib/data/language/LanguageList.class.php
+++ b/wcfsetup/install/files/lib/data/language/LanguageList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Language    current()
- * @method  Language[]  getObjects()
- * @method  Language|null   getSingleObject()
- * @method  Language|null   search($objectID)
- * @property    Language[] $objects
+ * @extends DatabaseObjectList<Language>
  */
 class LanguageList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryAction.class.php b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryAction.class.php
index a4161f896f9..59b2027c13b 100644
--- a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LanguageCategory        create()
- * @method  LanguageCategoryEditor[]    getObjects()
- * @method  LanguageCategoryEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<LanguageCategory, LanguageCategoryEditor>
  */
 class LanguageCategoryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryEditor.class.php b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryEditor.class.php
index 3c77ab2e4ea..63551f3416c 100644
--- a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static LanguageCategory    create(array $parameters = [])
- * @method      LanguageCategory    getDecoratedObject()
  * @mixin       LanguageCategory
+ * @extends DatabaseObjectEditor<LanguageCategory>
  */
 class LanguageCategoryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryList.class.php b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryList.class.php
index 9dbdf69bbc5..14182038605 100644
--- a/wcfsetup/install/files/lib/data/language/category/LanguageCategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/language/category/LanguageCategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LanguageCategory    current()
- * @method  LanguageCategory[]  getObjects()
- * @method  LanguageCategory|null   getSingleObject()
- * @method  LanguageCategory|null   search($objectID)
- * @property    LanguageCategory[] $objects
+ * @extends DatabaseObjectList<LanguageCategory>
  */
 class LanguageCategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/language/item/LanguageItemAction.class.php b/wcfsetup/install/files/lib/data/language/item/LanguageItemAction.class.php
index ddf042ba330..4a1b819b7d6 100644
--- a/wcfsetup/install/files/lib/data/language/item/LanguageItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/language/item/LanguageItemAction.class.php
@@ -12,10 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LanguageItem        create()
- * @method  LanguageItemEditor[]    getObjects()
- * @method  LanguageItemEditor  getSingleObject()
- * @property-read LanguageItemEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<LanguageItem, LanguageItemEditor>
  */
 class LanguageItemAction extends AbstractDatabaseObjectAction
 {
@@ -47,6 +44,7 @@ class LanguageItemAction extends AbstractDatabaseObjectAction
     /**
      * Creates multiple language items.
      *
+     * @return void
      * @since   5.2
      */
     public function createLanguageItems()
diff --git a/wcfsetup/install/files/lib/data/language/item/LanguageItemEditor.class.php b/wcfsetup/install/files/lib/data/language/item/LanguageItemEditor.class.php
index aa1db9c7326..c32880996bd 100644
--- a/wcfsetup/install/files/lib/data/language/item/LanguageItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/language/item/LanguageItemEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static LanguageItem    create(array $parameters = [])
- * @method      LanguageItem    getDecoratedObject()
  * @mixin       LanguageItem
+ * @extends DatabaseObjectEditor<LanguageItem>
  */
 class LanguageItemEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/language/item/LanguageItemList.class.php b/wcfsetup/install/files/lib/data/language/item/LanguageItemList.class.php
index 74eb2962f1d..0c16f4fbea5 100644
--- a/wcfsetup/install/files/lib/data/language/item/LanguageItemList.class.php
+++ b/wcfsetup/install/files/lib/data/language/item/LanguageItemList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LanguageItem        current()
- * @method  LanguageItem[]      getObjects()
- * @method  LanguageItem|null   getSingleObject()
- * @method  LanguageItem|null   search($objectID)
- * @property    LanguageItem[] $objects
+ * @extends DatabaseObjectList<LanguageItem>
  */
 class LanguageItemList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/like/ILikeObjectTypeProvider.class.php b/wcfsetup/install/files/lib/data/like/ILikeObjectTypeProvider.class.php
index 3f255e6d8ae..689e0fbeddb 100644
--- a/wcfsetup/install/files/lib/data/like/ILikeObjectTypeProvider.class.php
+++ b/wcfsetup/install/files/lib/data/like/ILikeObjectTypeProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\like;
 
+use wcf\data\DatabaseObject;
 use wcf\data\like\object\ILikeObject;
 use wcf\data\object\type\IObjectTypeProvider;
 
@@ -11,6 +12,9 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends IObjectTypeProvider<TDatabaseObject>
  */
 interface ILikeObjectTypeProvider extends IObjectTypeProvider
 {
diff --git a/wcfsetup/install/files/lib/data/like/IRestrictedLikeObjectTypeProvider.class.php b/wcfsetup/install/files/lib/data/like/IRestrictedLikeObjectTypeProvider.class.php
index 070a6134167..b6e297da192 100644
--- a/wcfsetup/install/files/lib/data/like/IRestrictedLikeObjectTypeProvider.class.php
+++ b/wcfsetup/install/files/lib/data/like/IRestrictedLikeObjectTypeProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\like;
 
+use wcf\data\DatabaseObject;
 use wcf\data\like\object\ILikeObject;
 
 /**
@@ -12,6 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends ILikeObjectTypeProvider<TDatabaseObject>
  */
 interface IRestrictedLikeObjectTypeProvider extends ILikeObjectTypeProvider
 {
diff --git a/wcfsetup/install/files/lib/data/like/LikeAction.class.php b/wcfsetup/install/files/lib/data/like/LikeAction.class.php
index 3ac12c25a18..6fae4c8495a 100644
--- a/wcfsetup/install/files/lib/data/like/LikeAction.class.php
+++ b/wcfsetup/install/files/lib/data/like/LikeAction.class.php
@@ -3,6 +3,7 @@
 namespace wcf\data\like;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
 use wcf\data\IGroupedUserListAction;
 use wcf\data\like\object\ILikeObject;
 use wcf\data\reaction\ReactionAction;
@@ -24,9 +25,18 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @deprecated  since 5.2, use \wcf\data\reaction\ReactionAction instead
  *
- * @method  Like        create()
- * @method  LikeEditor[]    getObjects()
- * @method  LikeEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Like, LikeEditor>
+ * @phpstan-type LikeData array{
+ *  likes: int,
+ *  dislikes: int,
+ *  cumulativeLikes: int,
+ *  isLiked: 1|0,
+ *  isDisliked: 1|0,
+ *  containerID: int,
+ *  newValue: 0,
+ *  oldValue: 0,
+ *  users: array{}
+ * }
  */
 class LikeAction extends AbstractDatabaseObjectAction implements IGroupedUserListAction
 {
@@ -54,12 +64,14 @@ class LikeAction extends AbstractDatabaseObjectAction implements IGroupedUserLis
 
     /**
      * like object type provider object
-     * @var ILikeObjectTypeProvider
+     * @var ILikeObjectTypeProvider<DatabaseObject>
      */
     public $objectTypeProvider;
 
     /**
      * Validates parameters to fetch like details.
+     *
+     * @return void
      */
     public function validateGetLikeDetails()
     {
@@ -69,7 +81,7 @@ public function validateGetLikeDetails()
     /**
      * Returns like details.
      *
-     * @return  string[]
+     * @return array{containerID: int, template: string}
      */
     public function getLikeDetails()
     {
@@ -116,6 +128,8 @@ public function getLikeDetails()
 
     /**
      * Validates parameters for like-related actions.
+     *
+     * @return void
      */
     public function validateLike()
     {
@@ -137,7 +151,7 @@ public function validateLike()
     }
 
     /**
-     * @inheritDoc
+     * @return LikeData
      */
     public function like()
     {
@@ -145,7 +159,7 @@ public function like()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     public function validateDislike()
     {
@@ -154,7 +168,7 @@ public function validateDislike()
     }
 
     /**
-     * @inheritDoc
+     * @return LikeData
      */
     public function dislike()
     {
@@ -166,7 +180,7 @@ public function dislike()
      * will revert the status (removing like/dislike).
      *
      * @param int $likeValue
-     * @return  array
+     * @return LikeData
      */
     protected function updateLike($likeValue)
     {
@@ -190,9 +204,9 @@ protected function updateLike($likeValue)
 
         // get stats
         return [
-            'likes' => ($likeData['data']['likes'] === null) ? 0 : $likeData['data']['likes'],
-            'dislikes' => ($likeData['data']['dislikes'] === null) ? 0 : $likeData['data']['dislikes'],
-            'cumulativeLikes' => ($likeData['data']['cumulativeLikes'] === null) ? 0 : $likeData['data']['cumulativeLikes'],
+            'likes' => $likeData['data']['likes'],
+            'dislikes' => $likeData['data']['dislikes'],
+            'cumulativeLikes' => $likeData['data']['cumulativeLikes'],
             'isLiked' => ($likeData['data']['liked'] == 1) ? 1 : 0,
             'isDisliked' => ($likeData['data']['liked'] == -1) ? 1 : 0,
             'containerID' => $this->parameters['data']['containerID'],
@@ -204,6 +218,8 @@ protected function updateLike($likeValue)
 
     /**
      * Validates permissions for given object.
+     *
+     * @return void
      */
     protected function validateObjectParameters()
     {
@@ -261,7 +277,7 @@ public function getGroupedUserList()
             $this->parameters['data']['objectID'],
             $this->objectType->objectTypeID,
         ]);
-        $pageCount = \ceil($statement->fetchSingleColumn() / 20);
+        $pageCount = (int)\ceil($statement->fetchSingleColumn() / 20);
 
         $sql = "SELECT      userID, likeValue
                 FROM        wcf1_like
@@ -307,6 +323,8 @@ public function getGroupedUserList()
 
     /**
      * Validates parameters to load likes.
+     *
+     * @return void
      */
     public function validateLoad()
     {
@@ -333,7 +351,7 @@ public function validateLoad()
     /**
      * Loads a list of likes.
      *
-     * @return  array
+     * @return array{lastLikeTime: int, template: string}|array{}
      */
     public function load()
     {
@@ -362,6 +380,8 @@ public function load()
 
     /**
      * Copies likes from one object id to another.
+     *
+     * @return void
      */
     public function copy()
     {
diff --git a/wcfsetup/install/files/lib/data/like/LikeEditor.class.php b/wcfsetup/install/files/lib/data/like/LikeEditor.class.php
index 6bd1a83518e..13d6341e53a 100644
--- a/wcfsetup/install/files/lib/data/like/LikeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/like/LikeEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Like    create(array $parameters = [])
- * @method      Like    getDecoratedObject()
  * @mixin       Like
+ * @extends DatabaseObjectEditor<Like>
  */
 class LikeEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/like/LikeList.class.php b/wcfsetup/install/files/lib/data/like/LikeList.class.php
index fc189d6b55e..68352ed8ebd 100644
--- a/wcfsetup/install/files/lib/data/like/LikeList.class.php
+++ b/wcfsetup/install/files/lib/data/like/LikeList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Like        current()
- * @method  Like[]      getObjects()
- * @method  Like|null   getSingleObject()
- * @method  Like|null   search($objectID)
- * @property    Like[] $objects
+ * @extends DatabaseObjectList<Like>
  */
 class LikeList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/like/ViewableLike.class.php b/wcfsetup/install/files/lib/data/like/ViewableLike.class.php
index d3892ee4aff..29802e18ed2 100644
--- a/wcfsetup/install/files/lib/data/like/ViewableLike.class.php
+++ b/wcfsetup/install/files/lib/data/like/ViewableLike.class.php
@@ -17,6 +17,7 @@
  *
  * @method  Like    getDecoratedObject()
  * @mixin   Like
+ * @extends DatabaseObjectDecorator<Like>
  */
 class ViewableLike extends DatabaseObjectDecorator
 {
@@ -58,6 +59,8 @@ class ViewableLike extends DatabaseObjectDecorator
 
     /**
      * Marks this like as accessible for current user.
+     *
+     * @return void
      */
     public function setIsAccessible()
     {
@@ -77,7 +80,7 @@ public function isAccessible()
     /**
      * Sets user profile.
      *
-     * @param UserProfile $userProfile
+     * @return void
      * @deprecated  3.0
      */
     public function setUserProfile(UserProfile $userProfile)
@@ -103,6 +106,7 @@ public function getUserProfile()
      * Sets like description.
      *
      * @param string $description
+     * @return void
      */
     public function setDescription($description)
     {
@@ -123,6 +127,7 @@ public function getDescription()
      * Sets like title.
      *
      * @param string $title
+     * @return void
      */
     public function setTitle($title)
     {
@@ -153,6 +158,7 @@ public function getObjectTypeName()
      * Sets the description of the object type displayed in the list of likes.
      *
      * @param string $name
+     * @return void
      * @since   3.1
      */
     public function setObjectTypeDescription($name)
diff --git a/wcfsetup/install/files/lib/data/like/object/AbstractLikeObject.class.php b/wcfsetup/install/files/lib/data/like/object/AbstractLikeObject.class.php
index 76575a4c06e..ccc140e7830 100644
--- a/wcfsetup/install/files/lib/data/like/object/AbstractLikeObject.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/AbstractLikeObject.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\like\object;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectDecorator;
 use wcf\data\like\Like;
 use wcf\data\object\type\ObjectType;
@@ -13,8 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LikeObject  getDecoratedObject()
  * @mixin   LikeObject
+ * @template TDatabaseObject of DatabaseObject
+ * @extends DatabaseObjectDecorator<TDatabaseObject>
  */
 abstract class AbstractLikeObject extends DatabaseObjectDecorator implements ILikeObject
 {
diff --git a/wcfsetup/install/files/lib/data/like/object/ILikeObject.class.php b/wcfsetup/install/files/lib/data/like/object/ILikeObject.class.php
index d37fed5bb2e..09014a5f575 100644
--- a/wcfsetup/install/files/lib/data/like/object/ILikeObject.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/ILikeObject.class.php
@@ -20,21 +20,21 @@ interface ILikeObject extends IDatabaseObjectProcessor, IIDObject, ITitledObject
     /**
      * Returns the url to this likeable.
      *
-     * @return  string
+     * @return string
      */
     public function getURL();
 
     /**
      * Returns the user id of the owner of this object.
      *
-     * @return  int
+     * @return int
      */
     public function getUserID();
 
     /**
      * Returns the likeable object type previously set via `setObjectType()`.
      *
-     * @return  ObjectType
+     * @return ObjectType
      */
     public function getObjectType();
 
@@ -42,27 +42,28 @@ public function getObjectType();
      * Updates the cumulative likes for this object.
      *
      * @param int $cumulativeLikes
+     * @return void
      */
     public function updateLikeCounter($cumulativeLikes);
 
     /**
      * Sets the likable object type.
      *
-     * @param ObjectType $objectType
+     * @return void
      */
     public function setObjectType(ObjectType $objectType);
 
     /**
      * Sends a notification for this like.
      *
-     * @param Like $like
+     * @return void
      */
     public function sendNotification(Like $like);
 
     /**
      * Returns the language id of this object or its parent or `null` if no explicit language is set.
      *
-     * @return  int|null
+     * @return ?int
      */
     public function getLanguageID();
 }
diff --git a/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php b/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
index 128c840b8b7..4711279ca02 100644
--- a/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
@@ -26,6 +26,12 @@
  * @property-read   string $cachedUsers        serialized array with the ids and names of the three users who liked (+1) the object last
  * @property-read   string $cachedReactions    serialized array with the reactionTypeIDs and the count of the reactions
  * @property-read   int $reactionTypeID
+ * @phpstan-type ReactionData array{
+ *  reactionCount: int,
+ *  renderedReactionIcon: string,
+ *  renderedReactionIconEncoded: string,
+ *  reactionTitle: string,
+ * }
  */
 class LikeObject extends DatabaseObject
 {
@@ -50,7 +56,7 @@ class LikeObject extends DatabaseObject
      * An array with all reaction types, which were received for the object. As key, the reactionTypeID
      * is used. As value there is another array. If the object does not received any reaction yet,
      * an empty array is returned.
-     * @var array
+     * @var array<int, ReactionData>
      */
     protected $reactions = [];
 
@@ -106,8 +112,8 @@ protected function handleData($data)
      * instead of the user (as the method name suggests). This behavior is intentional and helps
      * to establish backward compatibility.
      *
-     * @return  mixed[]
-     * @deprecated  since 5.2
+     * @return mixed[]
+     * @deprecated since 5.2
      */
     public function getUsers()
     {
@@ -134,7 +140,7 @@ public function getUsers()
     /**
      * Returns the liked object.
      *
-     * @return  ILikeObject
+     * @return ILikeObject
      */
     public function getLikedObject()
     {
@@ -149,20 +155,10 @@ public function getLikedObject()
     }
 
     /**
-     * Returns an array with all reaction types, which were received for the object. As key, the reactionTypeID
-     * is used. As value there is another array, which has the following structure:
+     * Returns an array with all reaction types, which were received for the object.
      *
-     * [
-     *      'reactionCount' => int,
-     *      'renderedReactionIcon' => string,
-     *      'renderedReactionIconEncoded' => string,
-     *      'reactionTitle' => string,
-     * ]
-     *
-     * If the object does not received any reaction yet, an empty array is returned.
-     *
-     * @return  array
-     * @since   5.2
+     * @return array<int, ReactionData>
+     * @since 5.2
      */
     public function getReactions()
     {
@@ -188,7 +184,7 @@ public function getReactionsJson(): string
     /**
      * Sets the liked object.
      *
-     * @param ILikeObject $likedObject
+     * @return void
      */
     public function setLikedObject(ILikeObject $likedObject)
     {
diff --git a/wcfsetup/install/files/lib/data/like/object/LikeObjectAction.class.php b/wcfsetup/install/files/lib/data/like/object/LikeObjectAction.class.php
index 0d1af15035b..a1bbc0e2b72 100644
--- a/wcfsetup/install/files/lib/data/like/object/LikeObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/LikeObjectAction.class.php
@@ -12,10 +12,6 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since        5.2
  *
- * @method  LikeObject  create()
- * @method  LikeObject[]    getObjects()
- * @method  LikeObject  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<LikeObject, LikeObjectEditor>
  */
-class LikeObjectAction extends AbstractDatabaseObjectAction
-{
-}
+class LikeObjectAction extends AbstractDatabaseObjectAction {}
diff --git a/wcfsetup/install/files/lib/data/like/object/LikeObjectEditor.class.php b/wcfsetup/install/files/lib/data/like/object/LikeObjectEditor.class.php
index 9bc402616df..19cd6278f28 100644
--- a/wcfsetup/install/files/lib/data/like/object/LikeObjectEditor.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/LikeObjectEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static LikeObject  create(array $parameters = [])
- * @method      LikeObject  getDecoratedObject()
  * @mixin       LikeObject
+ * @extends DatabaseObjectEditor<LikeObject>
  */
 class LikeObjectEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/like/object/LikeObjectList.class.php b/wcfsetup/install/files/lib/data/like/object/LikeObjectList.class.php
index c496ef221de..98860820309 100644
--- a/wcfsetup/install/files/lib/data/like/object/LikeObjectList.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/LikeObjectList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LikeObject      current()
- * @method  LikeObject[]        getObjects()
- * @method  LikeObject|null     getSingleObject()
- * @method  LikeObject|null     search($objectID)
- * @property    LikeObject[] $objects
+ * @extends DatabaseObjectList<LikeObject>
  */
 class LikeObjectList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/media/Media.class.php b/wcfsetup/install/files/lib/data/media/Media.class.php
index 862497bb9cb..4924c91938d 100644
--- a/wcfsetup/install/files/lib/data/media/Media.class.php
+++ b/wcfsetup/install/files/lib/data/media/Media.class.php
@@ -65,7 +65,11 @@ class Media extends DatabaseObject implements ILinkableObject, IRouteController,
 
     /**
      * data of the different thumbnail sizes
-     * @var array
+     * @var array<string, array{
+     *  height: int,
+     *  retainDimensions: bool|int,
+     *  width: int,
+     * }>
      */
     protected static $thumbnailSizes = [
         'tiny' => [
diff --git a/wcfsetup/install/files/lib/data/media/MediaAction.class.php b/wcfsetup/install/files/lib/data/media/MediaAction.class.php
index 2b84cab9958..a60f73dce03 100644
--- a/wcfsetup/install/files/lib/data/media/MediaAction.class.php
+++ b/wcfsetup/install/files/lib/data/media/MediaAction.class.php
@@ -31,10 +31,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Media       create()
- * @method  MediaEditor[]   getObjects()
- * @method  MediaEditor getSingleObject()
- * @property-read MediaEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Media, MediaEditor>
  */
 class MediaAction extends AbstractDatabaseObjectAction implements ISearchAction, IUploadAction
 {
@@ -126,6 +123,8 @@ public function upload()
 
     /**
      * Generates thumbnails.
+     *
+     * @return void
      */
     public function generateThumbnails()
     {
@@ -209,6 +208,8 @@ protected function getMediaData($media)
 
     /**
      * Validates the 'getManagementDialog' action.
+     *
+     * @return void
      */
     public function validateGetManagementDialog()
     {
@@ -260,8 +261,7 @@ public function getManagementDialog()
     /**
      * Returns the complete i18n data of the media files in the given list.
      *
-     * @param MediaList $mediaList
-     * @return  array
+     * @return mixed[]|array{}
      */
     protected function getI18nMediaData(MediaList $mediaList)
     {
@@ -307,6 +307,8 @@ protected function getI18nMediaData(MediaList $mediaList)
 
     /**
      * Validates the 'getEditorDialog' action.
+     *
+     * @return void
      */
     public function validateGetEditorDialog()
     {
@@ -641,6 +643,7 @@ public function delete()
      * all media files currently loaded are unmarked.
      *
      * @param int[] $mediaIDs ids of the media files to be unmarked
+     * @return void
      */
     protected function unmarkItems(array $mediaIDs = [])
     {
@@ -661,6 +664,7 @@ protected function unmarkItems(array $mediaIDs = [])
     /**
      * Validates the `getSetCategoryDialog` action.
      *
+     * @return void
      * @throws  PermissionDeniedException   if user is not allowed to set category of media files
      * @throws  IllegalLinkException        if no media file categories exist
      */
@@ -678,7 +682,7 @@ public function validateGetSetCategoryDialog()
     /**
      * Returns the dialog to set the category of multiple media files.
      *
-     * @return  string[]
+     * @return array{template: string}
      */
     public function getSetCategoryDialog()
     {
@@ -695,6 +699,7 @@ public function getSetCategoryDialog()
     /**
      * Validates the `setCategory` action.
      *
+     * @return void
      * @throws  PermissionDeniedException   if user is not allowed to edit a requested media file
      * @throws  UserInputException      if no object ids are given
      */
@@ -723,6 +728,8 @@ public function validateSetCategory()
 
     /**
      * Sets the category of multiple media files.
+     *
+     * @return void
      */
     public function setCategory()
     {
@@ -744,7 +751,8 @@ public function setCategory()
     /**
      * Validates the `replaceFile` action.
      *
-     * @since       5.3
+     * @return void
+     * @since 5.3
      */
     public function validateReplaceFile()
     {
@@ -761,8 +769,15 @@ public function validateReplaceFile()
     /**
      * Replaces the actual file of a media file.
      *
-     * @return      array
-     * @since       5.3
+     * @return array{
+     *  errors: array<int, array{
+     *      filename: string,
+     *      filesize: int,
+     *      errorType: string,
+     *  }>,
+     *  media: array<int, mixed[]>,
+     * }
+     * @since 5.3
      */
     public function replaceFile()
     {
diff --git a/wcfsetup/install/files/lib/data/media/MediaEditor.class.php b/wcfsetup/install/files/lib/data/media/MediaEditor.class.php
index e158b67a1f6..b406d182c6f 100644
--- a/wcfsetup/install/files/lib/data/media/MediaEditor.class.php
+++ b/wcfsetup/install/files/lib/data/media/MediaEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static Media   create(array $parameters = [])
- * @method      Media   getDecoratedObject()
  * @mixin       Media
+ * @extends DatabaseObjectEditor<Media>
  */
 class MediaEditor extends DatabaseObjectEditor
 {
@@ -25,6 +24,8 @@ class MediaEditor extends DatabaseObjectEditor
 
     /**
      * Deletes the physical files of the media file.
+     *
+     * @return void
      */
     public function deleteFiles()
     {
diff --git a/wcfsetup/install/files/lib/data/media/MediaList.class.php b/wcfsetup/install/files/lib/data/media/MediaList.class.php
index 685655cc388..31049a3d2ab 100644
--- a/wcfsetup/install/files/lib/data/media/MediaList.class.php
+++ b/wcfsetup/install/files/lib/data/media/MediaList.class.php
@@ -13,11 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Media       current()
- * @method  Media[]     getObjects()
- * @method  Media|null  getSingleObject()
- * @method  Media|null  search($objectID)
- * @property    Media[] $objects
+ * @extends DatabaseObjectList<Media>
  */
 class MediaList extends DatabaseObjectList
 {
@@ -30,6 +26,7 @@ class MediaList extends DatabaseObjectList
      * Adds conditions to search the media files by a certain search string.
      *
      * @param string $searchString
+     * @return void
      */
     public function addSearchConditions($searchString)
     {
diff --git a/wcfsetup/install/files/lib/data/media/ViewableMedia.class.php b/wcfsetup/install/files/lib/data/media/ViewableMedia.class.php
index 2c457cc60b3..324a6e19da6 100644
--- a/wcfsetup/install/files/lib/data/media/ViewableMedia.class.php
+++ b/wcfsetup/install/files/lib/data/media/ViewableMedia.class.php
@@ -17,11 +17,11 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Media   getDecoratedObject()
  * @mixin   Media
  * @property-read   string|null $title      title of the media file in the active user's language or `null` if object has not been fetched via `ViewableMediaList`
  * @property-read   string|null $caption    caption of the media file in the active user's language or `null` if object has not been fetched via `ViewableMediaList`
  * @property-read   string|null $altText    alternative text of the media file in the active user's language or `null` if object has not been fetched via `ViewableMediaList`
+ * @extends DatabaseObjectDecorator<Media>
  */
 class ViewableMedia extends DatabaseObjectDecorator
 {
@@ -53,6 +53,7 @@ class ViewableMedia extends DatabaseObjectDecorator
      *
      * @param int $languageID
      * @param string[] $content
+     * @return void
      */
     public function setLocalizedContent($languageID, array $content)
     {
@@ -63,7 +64,7 @@ public function setLocalizedContent($languageID, array $content)
      * Returns an instance of this class with localized versions.
      *
      * @param int $languageID
-     * @return      ViewableMedia
+     * @return ViewableMedia
      */
     public function getLocalizedVersion($languageID)
     {
@@ -81,6 +82,7 @@ public function getLocalizedVersion($languageID)
      * Forces the localized values by language id.
      *
      * @param int $languageID
+     * @return void
      */
     protected function forceLanguageID($languageID)
     {
@@ -100,7 +102,7 @@ public function __get($name)
     }
 
     /**
-     * @inheritDoc
+     * @return string
      */
     public function getTitle()
     {
diff --git a/wcfsetup/install/files/lib/data/menu/I18nMenuList.class.php b/wcfsetup/install/files/lib/data/menu/I18nMenuList.class.php
index 2eb453437a8..7ae6a467fcc 100644
--- a/wcfsetup/install/files/lib/data/menu/I18nMenuList.class.php
+++ b/wcfsetup/install/files/lib/data/menu/I18nMenuList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method  Menu        current()
- * @method  Menu[]      getObjects()
- * @method  Menu|null   getSingleObject()
- * @method  Menu|null   search($objectID)
- * @property    Menu[] $objects
+ * @extends I18nDatabaseObjectList<Menu>
  */
 class I18nMenuList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/menu/Menu.class.php b/wcfsetup/install/files/lib/data/menu/Menu.class.php
index ece4041cce0..cb93b82c7fe 100644
--- a/wcfsetup/install/files/lib/data/menu/Menu.class.php
+++ b/wcfsetup/install/files/lib/data/menu/Menu.class.php
@@ -5,6 +5,7 @@
 use wcf\data\box\Box;
 use wcf\data\DatabaseObject;
 use wcf\data\ITitledObject;
+use wcf\data\menu\item\MenuItemNode;
 use wcf\data\menu\item\MenuItemNodeTree;
 use wcf\system\WCF;
 
@@ -53,7 +54,7 @@ public function canDelete()
     /**
      * Returns the items of this menu.
      *
-     * @return  \RecursiveIteratorIterator
+     * @return  \RecursiveIteratorIterator<MenuItemNode>
      */
     public function getMenuItemNodeList()
     {
diff --git a/wcfsetup/install/files/lib/data/menu/MenuAction.class.php b/wcfsetup/install/files/lib/data/menu/MenuAction.class.php
index a0c73611b57..062339b7504 100644
--- a/wcfsetup/install/files/lib/data/menu/MenuAction.class.php
+++ b/wcfsetup/install/files/lib/data/menu/MenuAction.class.php
@@ -17,8 +17,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  MenuEditor[]    getObjects()
- * @method  MenuEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Menu, MenuEditor>
  */
 class MenuAction extends AbstractDatabaseObjectAction
 {
@@ -108,6 +107,9 @@ public function validateDelete()
         }
     }
 
+    /**
+     * @return array<string, string>
+     */
     #[\Override]
     public function getI18nSaveTypes(): array
     {
diff --git a/wcfsetup/install/files/lib/data/menu/MenuEditor.class.php b/wcfsetup/install/files/lib/data/menu/MenuEditor.class.php
index 304a7f53565..c4b2e6abb95 100644
--- a/wcfsetup/install/files/lib/data/menu/MenuEditor.class.php
+++ b/wcfsetup/install/files/lib/data/menu/MenuEditor.class.php
@@ -16,8 +16,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Menu    getDecoratedObject()
  * @mixin   Menu
+ * @extends DatabaseObjectEditor<Menu>
+ * @implements IEditableCachedObject<Menu>
  */
 class MenuEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/menu/MenuList.class.php b/wcfsetup/install/files/lib/data/menu/MenuList.class.php
index 8dc33d623e9..cafee85fade 100644
--- a/wcfsetup/install/files/lib/data/menu/MenuList.class.php
+++ b/wcfsetup/install/files/lib/data/menu/MenuList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Menu        current()
- * @method  Menu[]      getObjects()
- * @method  Menu|null   getSingleObject()
- * @method  Menu|null   search($objectID)
- * @property    Menu[] $objects
+ * @extends DatabaseObjectList<Menu>
  */
 class MenuList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/menu/item/MenuItemAction.class.php b/wcfsetup/install/files/lib/data/menu/item/MenuItemAction.class.php
index 644aba7a4f0..e44373ddd1a 100644
--- a/wcfsetup/install/files/lib/data/menu/item/MenuItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/menu/item/MenuItemAction.class.php
@@ -21,8 +21,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  MenuItemEditor[]    getObjects()
- * @method  MenuItemEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<MenuItem, MenuItemEditor>
  */
 class MenuItemAction extends AbstractDatabaseObjectAction implements ISortableAction, IToggleAction
 {
@@ -168,6 +167,9 @@ public function updatePosition()
         WCF::getDB()->commitTransaction();
     }
 
+    /**
+     * @return array<string, string>
+     */
     #[\Override]
     public function getI18nSaveTypes(): array
     {
diff --git a/wcfsetup/install/files/lib/data/menu/item/MenuItemEditor.class.php b/wcfsetup/install/files/lib/data/menu/item/MenuItemEditor.class.php
index df678947e90..1a95c414162 100644
--- a/wcfsetup/install/files/lib/data/menu/item/MenuItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/menu/item/MenuItemEditor.class.php
@@ -16,8 +16,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  MenuItem    getDecoratedObject()
  * @mixin   MenuItem
+ * @extends DatabaseObjectEditor<MenuItem>
+ * @implements IEditableCachedObject<MenuItem>
  */
 class MenuItemEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/menu/item/MenuItemList.class.php b/wcfsetup/install/files/lib/data/menu/item/MenuItemList.class.php
index 122a5fcff56..9c4a2c29db8 100644
--- a/wcfsetup/install/files/lib/data/menu/item/MenuItemList.class.php
+++ b/wcfsetup/install/files/lib/data/menu/item/MenuItemList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  MenuItem    current()
- * @method  MenuItem[]  getObjects()
- * @method  MenuItem|null   getSingleObject()
- * @method  MenuItem|null   search($objectID)
- * @property    MenuItem[] $objects
+ * @extends DatabaseObjectList<MenuItem>
  */
 class MenuItemList extends DatabaseObjectList
 {
@@ -29,6 +25,7 @@ class MenuItemList extends DatabaseObjectList
      * Sets the menu items used to improve menu cache performance.
      *
      * @param MenuItem[] $menuItems list of menu item objects
+     * @return void
      */
     public function setMenuItems(array $menuItems)
     {
diff --git a/wcfsetup/install/files/lib/data/menu/item/MenuItemNode.class.php b/wcfsetup/install/files/lib/data/menu/item/MenuItemNode.class.php
index 9636da8e5c7..abc9f02d945 100644
--- a/wcfsetup/install/files/lib/data/menu/item/MenuItemNode.class.php
+++ b/wcfsetup/install/files/lib/data/menu/item/MenuItemNode.class.php
@@ -14,8 +14,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  MenuItem    getDecoratedObject()
  * @mixin   MenuItem
+ * @extends DatabaseObjectDecorator<MenuItem>
  */
 class MenuItemNode extends DatabaseObjectDecorator implements IObjectTreeNode
 {
diff --git a/wcfsetup/install/files/lib/data/menu/item/MenuItemNodeTree.class.php b/wcfsetup/install/files/lib/data/menu/item/MenuItemNodeTree.class.php
index 2b434a954c9..eee399551f1 100644
--- a/wcfsetup/install/files/lib/data/menu/item/MenuItemNodeTree.class.php
+++ b/wcfsetup/install/files/lib/data/menu/item/MenuItemNodeTree.class.php
@@ -176,7 +176,7 @@ public function getNodeTree()
     /**
      * Returns the iterable node list.
      *
-     * @return  \RecursiveIteratorIterator
+     * @return \RecursiveIteratorIterator<MenuItemNode>
      */
     public function getNodeList()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueue.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueue.class.php
index 342d267cb3f..ffc888d2637 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueue.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueue.class.php
@@ -24,7 +24,7 @@
  * @property-read   int $status         status of the moderation queue entry (see `ModerationQueue::STATUS_*` constants)
  * @property-read   int $comments       number of comments on the moderation queue entry
  * @property-read   int $lastChangeTime     timestamp at which the moderation queue entry has been changed the last time
- * @property-read   array $additionalData     array with additional data of the moderation queue entry
+ * @property-read   mixed[] $additionalData     array with additional data of the moderation queue entry
  * @property-read   bool $markAsJustified    true if the report was closed, but it was actually justified and other actions may have been taken
  * @property-read   string $message
  */
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueAction.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueAction.class.php
index c673cfba9df..4a107576636 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueAction.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueAction.class.php
@@ -23,9 +23,7 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ModerationQueueEditor[]     getObjects()
- * @method  ModerationQueueEditor       getSingleObject()
- * @property-read ModerationQueueEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<ModerationQueue, ModerationQueueEditor>
  */
 class ModerationQueueAction extends AbstractDatabaseObjectAction
 {
@@ -48,7 +46,6 @@ class ModerationQueueAction extends AbstractDatabaseObjectAction
 
     /**
      * @inheritDoc
-     * @return  ModerationQueue
      */
     public function create()
     {
@@ -56,9 +53,7 @@ public function create()
             $this->parameters['data']['lastChangeTime'] = TIME_NOW;
         }
 
-        $object = parent::create();
-        \assert($object instanceof ModerationQueue);
-        return $object;
+        return parent::create();
     }
 
     /**
@@ -75,6 +70,8 @@ public function update()
 
     /**
      * Marks a list of objects as done.
+     *
+     * @return void
      */
     public function markAsDone()
     {
@@ -101,6 +98,7 @@ public function markAsDone()
     }
 
     /**
+     * @return void
      * @since 5.5
      */
     public function validateGetModerationQueueData(): void
@@ -109,6 +107,15 @@ public function validateGetModerationQueueData(): void
     }
 
     /**
+     * @return array{items: list<array{
+     *  content: string,
+     *  image: string,
+     *  isUnread: bool,
+     *  link: string,
+     *  objectId: int,
+     *  time: int,
+     *  usernames: string[],
+     * }>, totalCount: int}
      * @since 5.5
      */
     public function getModerationQueueData(): array
@@ -134,6 +141,7 @@ public function getModerationQueueData(): array
     }
 
     /**
+     * @return array{queues: list<ViewableModerationQueue>, totalCount: int}
      * @since 5.5
      * @deprecated 5.5 This method will be merged with `getModerationQueueData`
      */
@@ -220,6 +228,8 @@ private function getModerationQueues(): array
 
     /**
      * Marks queue entries as read.
+     *
+     * @return void|array{markAsRead: int, totalCount: int}
      */
     public function markAsRead()
     {
@@ -253,7 +263,7 @@ public function markAsRead()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     public function validateMarkAsRead()
     {
@@ -270,6 +280,8 @@ public function validateMarkAsRead()
 
     /**
      * Marks all queue entries as read.
+     *
+     * @return array{markAllAsRead: bool}
      */
     public function markAllAsRead()
     {
@@ -285,6 +297,8 @@ public function markAllAsRead()
 
     /**
      * Validates the mark all as read action.
+     *
+     * @return void
      */
     public function validateMarkAllAsRead()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueActivationAction.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueActivationAction.class.php
index 8a43b40ad68..162ce8af432 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueActivationAction.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueActivationAction.class.php
@@ -30,6 +30,8 @@ class ModerationQueueActivationAction extends ModerationQueueAction
 
     /**
      * Validates parameters to enable content.
+     *
+     * @return void
      */
     public function validateEnableContent()
     {
@@ -50,6 +52,8 @@ public function validateEnableContent()
 
     /**
      * Enables content.
+     *
+     * @return void
      */
     public function enableContent()
     {
@@ -68,6 +72,8 @@ public function enableContent()
 
     /**
      * Validates parameters to delete reported content.
+     *
+     * @return void
      */
     public function validateRemoveContent()
     {
@@ -83,6 +89,8 @@ public function validateRemoveContent()
 
     /**
      * Deletes reported content.
+     *
+     * @return void
      */
     public function removeContent()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueEditor.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueEditor.class.php
index a0977da3f4c..27e717cea64 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueEditor.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ModerationQueue     create(array $parameters = [])
- * @method      ModerationQueue     getDecoratedObject()
  * @mixin       ModerationQueue
+ * @extends DatabaseObjectEditor<ModerationQueue>
  */
 class ModerationQueueEditor extends DatabaseObjectEditor
 {
@@ -26,6 +25,8 @@ class ModerationQueueEditor extends DatabaseObjectEditor
     /**
      * Marks this entry as confirmed, e.g. report was justified and content was deleted or
      * content was approved.
+     *
+     * @return void
      */
     public function markAsConfirmed()
     {
@@ -39,6 +40,7 @@ public function markAsConfirmed()
      * Marks this entry as rejected, e.g. report was unjustified or content approval was denied.
      *
      * @param bool $markAsJustified
+     * @return void
      */
     public function markAsRejected($markAsJustified = false)
     {
@@ -58,6 +60,8 @@ public function markAsRejected($markAsJustified = false)
 
     /**
      * Marks this entry as in progress.
+     *
+     * @return void
      */
     public function markAsInProgress()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueList.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueList.class.php
index 8d20cf73a06..a40292899b1 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueList.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\moderation\queue;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -11,11 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ModerationQueue     current()
- * @method  ModerationQueue[]   getObjects()
- * @method  ModerationQueue|null    getSingleObject()
- * @method  ModerationQueue|null    search($objectID)
- * @property    ModerationQueue[] $objects
+ * @template-covariant TDatabaseObject of ModerationQueue|DatabaseObjectDecorator<ModerationQueue> = ModerationQueue
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class ModerationQueueList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueReportAction.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueReportAction.class.php
index b563aa76b01..8a5811464f4 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueReportAction.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ModerationQueueReportAction.class.php
@@ -34,6 +34,8 @@ class ModerationQueueReportAction extends ModerationQueueAction
 
     /**
      * Validates parameters to delete reported content.
+     *
+     * @return void
      */
     public function validateRemoveContent()
     {
@@ -50,6 +52,8 @@ public function validateRemoveContent()
 
     /**
      * Deletes reported content.
+     *
+     * @return void
      */
     public function removeContent()
     {
@@ -67,6 +71,8 @@ public function removeContent()
 
     /**
      * Validates parameters to mark this report as done.
+     *
+     * @return void
      */
     public function validateRemoveReport()
     {
@@ -96,6 +102,8 @@ public function validateRemoveReport()
 
     /**
      * Removes this report by marking it as done without further processing.
+     *
+     * @return void
      */
     public function removeReport()
     {
@@ -110,6 +118,8 @@ public function removeReport()
 
     /**
      * Validates parameters to prepare a report.
+     *
+     * @return void
      */
     public function validatePrepareReport()
     {
@@ -145,6 +155,8 @@ public function validatePrepareReport()
 
     /**
      * Prepares a report.
+     *
+     * @return array{alreadyReported: 0|1, template: string}
      */
     public function prepareReport()
     {
@@ -168,6 +180,8 @@ public function prepareReport()
 
     /**
      * Validates parameters for reporting.
+     *
+     * @return void
      */
     public function validateReport()
     {
@@ -192,6 +206,8 @@ public function validateReport()
 
     /**
      * Reports an item.
+     *
+     * @return array{reported: 1}
      */
     public function report()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueue.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueue.class.php
index e5b607d88d2..84c8a756c3f 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueue.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueue.class.php
@@ -26,8 +26,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ModerationQueue     getDecoratedObject()
  * @mixin   ModerationQueue
+ * @extends DatabaseObjectDecorator<ModerationQueue>
  */
 class ViewableModerationQueue extends DatabaseObjectDecorator implements ILinkableObject, ITitledObject
 {
@@ -57,7 +57,7 @@ class ViewableModerationQueue extends DatabaseObjectDecorator implements ILinkab
     /**
      * Sets link for viewing/editing.
      *
-     * @param IUserContent $object
+     * @return void
      */
     public function setAffectedObject(IUserContent $object)
     {
@@ -93,7 +93,7 @@ public function getAffectedObject()
     /**
      * Sets associated user profile object.
      *
-     * @param UserProfile $userProfile
+     * @return void
      * @deprecated  3.0
      */
     public function setUserProfile(UserProfile $userProfile)
@@ -147,6 +147,8 @@ public function isOrphaned()
 
     /**
      * Marks associated objects as removed.
+     *
+     * @return void
      */
     public function setIsOrphaned()
     {
diff --git a/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueueList.class.php b/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueueList.class.php
index ccd8ca2d63f..a1d8db55bff 100644
--- a/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueueList.class.php
+++ b/wcfsetup/install/files/lib/data/moderation/queue/ViewableModerationQueueList.class.php
@@ -18,11 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ViewableModerationQueue     current()
- * @method  ViewableModerationQueue[]   getObjects()
- * @method  ViewableModerationQueue|null    getSingleObject()
- * @method  ViewableModerationQueue|null    search($objectID)
- * @property    ViewableModerationQueue[] $objects
+ * @extends ModerationQueueList<ViewableModerationQueue>
  */
 class ViewableModerationQueueList extends ModerationQueueList
 {
diff --git a/wcfsetup/install/files/lib/data/modification/log/ModificationLog.class.php b/wcfsetup/install/files/lib/data/modification/log/ModificationLog.class.php
index 016fab4c1ac..1ba34b0e529 100644
--- a/wcfsetup/install/files/lib/data/modification/log/ModificationLog.class.php
+++ b/wcfsetup/install/files/lib/data/modification/log/ModificationLog.class.php
@@ -19,7 +19,7 @@
  * @property-read   string $username       name of the user or guest who caused the modification log entry
  * @property-read   int $time           timestamp at which the modification log entry has been created
  * @property-read   string $action         name of the modification action that is logged
- * @property-read   array $additionalData     array with additional data of the modification log entry
+ * @property-read   mixed[] $additionalData     array with additional data of the modification log entry
  */
 class ModificationLog extends DatabaseObject
 {
diff --git a/wcfsetup/install/files/lib/data/modification/log/ModificationLogAction.class.php b/wcfsetup/install/files/lib/data/modification/log/ModificationLogAction.class.php
index 1cf5d0689e9..1201d0abbfe 100644
--- a/wcfsetup/install/files/lib/data/modification/log/ModificationLogAction.class.php
+++ b/wcfsetup/install/files/lib/data/modification/log/ModificationLogAction.class.php
@@ -11,10 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ModificationLog         create()
- * @method  ModificationLogEditor[]     getObjects()
- * @method  ModificationLogEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ModificationLog, ModificationLogEditor>
  */
-class ModificationLogAction extends AbstractDatabaseObjectAction
-{
-}
+class ModificationLogAction extends AbstractDatabaseObjectAction {}
diff --git a/wcfsetup/install/files/lib/data/modification/log/ModificationLogEditor.class.php b/wcfsetup/install/files/lib/data/modification/log/ModificationLogEditor.class.php
index b77d64af1c2..6fea6633897 100644
--- a/wcfsetup/install/files/lib/data/modification/log/ModificationLogEditor.class.php
+++ b/wcfsetup/install/files/lib/data/modification/log/ModificationLogEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ModificationLog     create(array $parameters = [])
- * @method      ModificationLog     getDecoratedObject()
  * @mixin       ModificationLog
+ * @extends DatabaseObjectEditor<ModificationLog>
  */
 class ModificationLogEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/modification/log/ModificationLogList.class.php b/wcfsetup/install/files/lib/data/modification/log/ModificationLogList.class.php
index 6e3c83c959c..9112f8f7d67 100644
--- a/wcfsetup/install/files/lib/data/modification/log/ModificationLogList.class.php
+++ b/wcfsetup/install/files/lib/data/modification/log/ModificationLogList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ModificationLog     current()
- * @method  ModificationLog[]   getObjects()
- * @method  ModificationLog|null    getSingleObject()
- * @method  ModificationLog|null    search($objectID)
- * @property    ModificationLog[] $objects
+ * @extends DatabaseObjectList<ModificationLog>
  */
 class ModificationLogList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/notice/NoticeAction.class.php b/wcfsetup/install/files/lib/data/notice/NoticeAction.class.php
index fab8522bd38..467a2487ce0 100644
--- a/wcfsetup/install/files/lib/data/notice/NoticeAction.class.php
+++ b/wcfsetup/install/files/lib/data/notice/NoticeAction.class.php
@@ -18,9 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  NoticeEditor[]      getObjects()
- * @method  NoticeEditor        getSingleObject()
- * @property-read NoticeEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Notice, NoticeEditor>
  */
 class NoticeAction extends AbstractDatabaseObjectAction implements ISortableAction, IToggleAction
 {
@@ -115,6 +113,8 @@ public function dismiss()
 
     /**
      * Validates the 'dismiss' action.
+     *
+     * @return void
      */
     public function validateDismiss()
     {
diff --git a/wcfsetup/install/files/lib/data/notice/NoticeEditor.class.php b/wcfsetup/install/files/lib/data/notice/NoticeEditor.class.php
index f74e3ecce2e..c1baac8bf72 100644
--- a/wcfsetup/install/files/lib/data/notice/NoticeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/notice/NoticeEditor.class.php
@@ -16,9 +16,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Notice      create(array $parameters = [])
- * @method      Notice      getDecoratedObject()
  * @mixin       Notice
+ * @extends DatabaseObjectEditor<Notice>
+ * @implements IEditableCachedObject<Notice>
  */
 class NoticeEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -31,6 +31,7 @@ class NoticeEditor extends DatabaseObjectEditor implements IEditableCachedObject
      * Sets the show order of the notice.
      *
      * @param int $showOrder
+     * @return void
      */
     public function setShowOrder($showOrder = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/notice/NoticeList.class.php b/wcfsetup/install/files/lib/data/notice/NoticeList.class.php
index 7225e07cce4..b3b10aada1b 100644
--- a/wcfsetup/install/files/lib/data/notice/NoticeList.class.php
+++ b/wcfsetup/install/files/lib/data/notice/NoticeList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Notice      current()
- * @method  Notice[]    getObjects()
- * @method  Notice|null getSingleObject()
- * @method  Notice|null search($objectID)
- * @property    Notice[] $objects
+ * @extends DatabaseObjectList<Notice>
  */
-class NoticeList extends DatabaseObjectList
-{
-}
+class NoticeList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProcessor.class.php b/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProcessor.class.php
index 16163dfaf71..ec2f09f8fc3 100644
--- a/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProcessor.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProcessor.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectType  getDecoratedObject()
  * @mixin   ObjectType
+ * @extends DatabaseObjectDecorator<ObjectType>
  */
 abstract class AbstractObjectTypeProcessor extends DatabaseObjectDecorator implements IDatabaseObjectProcessor
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProvider.class.php b/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProvider.class.php
index da829f6a939..090ce33b089 100644
--- a/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProvider.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/AbstractObjectTypeProvider.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\data\object\type;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -10,6 +12,9 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @implements IObjectTypeProvider<TDatabaseObject>
  */
 abstract class AbstractObjectTypeProvider implements IObjectTypeProvider
 {
@@ -52,7 +57,7 @@ public function getObjectsByIDs(array $objectIDs)
         $tableAlias = \call_user_func([$this->className, 'getDatabaseTableAlias']);
         $tableIndex = \call_user_func([$this->className, 'getDatabaseTableIndexName']);
 
-        /** @var DatabaseObjectList $objectList */
+        /** @var DatabaseObjectList<TDatabaseObject> $objectList */
         $objectList = new $this->listClassName();
         if ($this->decoratorClassName) {
             $objectList->decoratorClassName = $this->decoratorClassName;
diff --git a/wcfsetup/install/files/lib/data/object/type/IObjectTypeProvider.class.php b/wcfsetup/install/files/lib/data/object/type/IObjectTypeProvider.class.php
index 6101a740a08..0c724e92b39 100644
--- a/wcfsetup/install/files/lib/data/object/type/IObjectTypeProvider.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/IObjectTypeProvider.class.php
@@ -3,6 +3,7 @@
 namespace wcf\data\object\type;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 
 /**
  * Any object type provider should implement this interface.
@@ -10,6 +11,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
  */
 interface IObjectTypeProvider
 {
@@ -17,7 +20,7 @@ interface IObjectTypeProvider
      * Returns an object by its ID.
      *
      * @param int $objectID
-     * @return  DatabaseObject
+     * @return TDatabaseObject
      */
     public function getObjectByID($objectID);
 
@@ -25,7 +28,7 @@ public function getObjectByID($objectID);
      * Returns objects by their IDs.
      *
      * @param int[] $objectIDs
-     * @return  DatabaseObject[]
+     * @return TDatabaseObject[]
      */
     public function getObjectsByIDs(array $objectIDs);
 }
diff --git a/wcfsetup/install/files/lib/data/object/type/ObjectType.class.php b/wcfsetup/install/files/lib/data/object/type/ObjectType.class.php
index 1a795dc1e52..25a23061f51 100644
--- a/wcfsetup/install/files/lib/data/object/type/ObjectType.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/ObjectType.class.php
@@ -25,7 +25,7 @@
  * @property-read   int $packageID      id of the package the which delivers the object type
  * @property-read   string $objectType     textual identifier of the object type
  * @property-read   string $className      PHP class name of the object type processor (implementing the interface forced by the object type definition)
- * @property-read   array $additionalData     array with additional data of the object type
+ * @property-read   mixed[] $additionalData     array with additional data of the object type
  */
 class ObjectType extends ProcessibleDatabaseObject
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/ObjectTypeAction.class.php b/wcfsetup/install/files/lib/data/object/type/ObjectTypeAction.class.php
index 67aabaa8ae7..2d4a63a540f 100644
--- a/wcfsetup/install/files/lib/data/object/type/ObjectTypeAction.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/ObjectTypeAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectType      create()
- * @method  ObjectTypeEditor[]  getObjects()
- * @method  ObjectTypeEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ObjectType, ObjectTypeEditor>
  */
 class ObjectTypeAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/ObjectTypeCache.class.php b/wcfsetup/install/files/lib/data/object/type/ObjectTypeCache.class.php
index 059101989f7..1e3913b47fa 100644
--- a/wcfsetup/install/files/lib/data/object/type/ObjectTypeCache.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/ObjectTypeCache.class.php
@@ -17,31 +17,31 @@ class ObjectTypeCache extends SingletonFactory
 {
     /**
      * object type definitions
-     * @var ObjectTypeDefinition[]
+     * @var array<int, ObjectTypeDefinition>
      */
     protected $definitions = [];
 
     /**
      * object type definition ids grouped by category name
-     * @var int[][]
+     * @var array<string, list<int>>
      */
     protected $definitionsByCategory = [];
 
     /**
      * object type definitions sorted by name
-     * @var ObjectTypeDefinition[]
+     * @var array<string, ObjectTypeDefinition>
      */
     protected $definitionsByName = [];
 
     /**
      * object types
-     * @var ObjectType[]
+     * @var array<int, ObjectType>
      */
     protected $objectTypes = [];
 
     /**
      * object types grouped by definition
-     * @var array
+     * @var array<string, array<string, ObjectType>>
      */
     protected $groupedObjectTypes = [];
 
@@ -67,7 +67,7 @@ protected function init()
      * object type definition exists.
      *
      * @param int $definitionID
-     * @return  ObjectTypeDefinition|null
+     * @return ?ObjectTypeDefinition
      */
     public function getDefinition($definitionID)
     {
@@ -79,7 +79,7 @@ public function getDefinition($definitionID)
      * such object type definition exists.
      *
      * @param string $definitionName
-     * @return  ObjectTypeDefinition|null
+     * @return ?ObjectTypeDefinition
      */
     public function getDefinitionByName($definitionName)
     {
@@ -91,7 +91,7 @@ public function getDefinitionByName($definitionName)
      * category name is invalid.
      *
      * @param string $categoryName
-     * @return  ObjectTypeDefinition[]|null
+     * @return array<int, ObjectTypeDefinition>|null
      */
     public function getDefinitionsByCategory($categoryName)
     {
@@ -112,7 +112,7 @@ public function getDefinitionsByCategory($categoryName)
      * exists.
      *
      * @param int $objectTypeID
-     * @return  ObjectType|null
+     * @return ?ObjectType
      */
     public function getObjectType($objectTypeID)
     {
@@ -123,7 +123,7 @@ public function getObjectType($objectTypeID)
      * Returns the list of object type with the given definition name.
      *
      * @param string $definitionName
-     * @return  ObjectType[]
+     * @return array<string, ObjectType>
      */
     public function getObjectTypes($definitionName)
     {
@@ -140,7 +140,7 @@ public function getObjectTypes($definitionName)
      *
      * @param string $definitionName
      * @param string $objectTypeName
-     * @return  ObjectType|null
+     * @return ?ObjectType
      */
     public function getObjectTypeByName($definitionName, $objectTypeName)
     {
@@ -159,7 +159,7 @@ public function getObjectTypeByName($definitionName, $objectTypeName)
      *
      * @param string $definitionName
      * @param string $objectTypeName
-     * @return  int|null
+     * @return ?int
      */
     public function getObjectTypeIDByName($definitionName, $objectTypeName)
     {
@@ -173,6 +173,8 @@ public function getObjectTypeIDByName($definitionName, $objectTypeName)
 
     /**
      * Resets and reloads the object type cache.
+     *
+     * @return void
      */
     public function resetCache()
     {
diff --git a/wcfsetup/install/files/lib/data/object/type/ObjectTypeEditor.class.php b/wcfsetup/install/files/lib/data/object/type/ObjectTypeEditor.class.php
index 6a3f35de15d..81c49c6c964 100644
--- a/wcfsetup/install/files/lib/data/object/type/ObjectTypeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/ObjectTypeEditor.class.php
@@ -12,9 +12,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ObjectType  create(array $parameters = [])
- * @method      ObjectType  getDecoratedObject()
  * @mixin       ObjectType
+ * @extends DatabaseObjectEditor<ObjectType>
+ * @implements IEditableCachedObject<ObjectType>
  */
 class ObjectTypeEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/ObjectTypeList.class.php b/wcfsetup/install/files/lib/data/object/type/ObjectTypeList.class.php
index 7a59b2711c3..bd4663e0dff 100644
--- a/wcfsetup/install/files/lib/data/object/type/ObjectTypeList.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/ObjectTypeList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectType      current()
- * @method  ObjectType[]        getObjects()
- * @method  ObjectType|null     getSingleObject()
- * @method  ObjectType|null     search($objectID)
- * @property    ObjectType[] $objects
+ * @extends DatabaseObjectList<ObjectType>
  */
 class ObjectTypeList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionAction.class.php b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionAction.class.php
index 9170964b1bd..0f89b7907ef 100644
--- a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionAction.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectTypeDefinition        create()
- * @method  ObjectTypeDefinitionEditor[]    getObjects()
- * @method  ObjectTypeDefinitionEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ObjectTypeDefinition, ObjectTypeDefinitionEditor>
  */
 class ObjectTypeDefinitionAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionEditor.class.php b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionEditor.class.php
index f0d8c66beac..16d37b8da66 100644
--- a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static ObjectTypeDefinition    create(array $parameters = [])
- * @method      ObjectTypeDefinition    getDecoratedObject()
  * @mixin       ObjectTypeDefinition
+ * @extends DatabaseObjectEditor<ObjectTypeDefinition>
  */
 class ObjectTypeDefinitionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionList.class.php b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionList.class.php
index f03a0c7e737..43d87513d93 100644
--- a/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionList.class.php
+++ b/wcfsetup/install/files/lib/data/object/type/definition/ObjectTypeDefinitionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectTypeDefinition        current()
- * @method  ObjectTypeDefinition[]      getObjects()
- * @method  ObjectTypeDefinition|null   getSingleObject()
- * @method  ObjectTypeDefinition|null   search($objectID)
- * @property    ObjectTypeDefinition[] $objects
+ * @extends DatabaseObjectList<ObjectTypeDefinition>
  */
 class ObjectTypeDefinitionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/option/Option.class.php b/wcfsetup/install/files/lib/data/option/Option.class.php
index 34ec6e304ca..7210ee9a7f5 100644
--- a/wcfsetup/install/files/lib/data/option/Option.class.php
+++ b/wcfsetup/install/files/lib/data/option/Option.class.php
@@ -31,7 +31,7 @@
  * @property-read   string $options        comma separated list of options of which at least one needs to be enabled for the option to be editable
  * @property-read   int $supportI18n        is `1` if the option supports different values for all available languages, otherwise `0`
  * @property-read   int $requireI18n        is `1` if `$supportI18n = 1` and the option's value has to explicitly set for all values so that the `monolingual` option is not available, otherwise `0`
- * @property-read   array $additionalData     array with additional data of the option
+ * @property-read   mixed[] $additionalData     array with additional data of the option
  */
 class Option extends DatabaseObject
 {
@@ -69,7 +69,7 @@ protected function handleData($data)
     /**
      * Returns a list of options.
      *
-     * @return  static[]
+     * @return static[]
      */
     public static function getOptions(): array
     {
@@ -105,7 +105,7 @@ public static function getOptionByName(string $optionName): static|null
      * Parses enableOptions.
      *
      * @param string $optionData
-     * @return  array
+     * @return array{disableOptions: string, enableOptions: string}
      */
     public static function parseEnableOptions($optionData)
     {
@@ -138,7 +138,7 @@ public static function parseEnableOptions($optionData)
     /**
      * Returns a list of the available options.
      *
-     * @return  array
+     * @return array<string, string>
      */
     public function parseSelectOptions()
     {
@@ -161,7 +161,7 @@ public function parseSelectOptions()
     /**
      * Returns a list of the enable options.
      *
-     * @return  array
+     * @return array<string, string>
      */
     public function parseMultipleEnableOptions()
     {
@@ -189,7 +189,7 @@ public function parseMultipleEnableOptions()
     /**
      * Returns true if option is visible
      *
-     * @return  bool
+     * @return bool
      */
     public function isVisible()
     {
@@ -207,7 +207,7 @@ public static function getDatabaseTableAlias()
     /**
      * Returns the constant name.
      *
-     * @return  string
+     * @return string
      */
     public function getConstantName()
     {
@@ -218,6 +218,7 @@ public function getConstantName()
      * Allows modifications of select options.
      *
      * @param string $selectOptions
+     * @return void
      */
     public function modifySelectOptions($selectOptions)
     {
@@ -228,6 +229,7 @@ public function modifySelectOptions($selectOptions)
      * Allows modifications of enable options.
      *
      * @param string $enableOptions
+     * @return void
      */
     public function modifyEnableOptions($enableOptions)
     {
@@ -238,6 +240,7 @@ public function modifyEnableOptions($enableOptions)
      * Allows modifications of hidden option.
      *
      * @param string $hiddenOption
+     * @return void
      */
     public function modifyHiddenOption($hiddenOption)
     {
diff --git a/wcfsetup/install/files/lib/data/option/OptionAction.class.php b/wcfsetup/install/files/lib/data/option/OptionAction.class.php
index 0f67249aace..97ed9f4f575 100644
--- a/wcfsetup/install/files/lib/data/option/OptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/option/OptionAction.class.php
@@ -16,9 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Option      create()
- * @method  OptionEditor[]  getObjects()
- * @method  OptionEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Option, OptionEditor>
  */
 class OptionAction extends AbstractDatabaseObjectAction
 {
@@ -57,6 +55,8 @@ class OptionAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateImport()
     {
@@ -65,6 +65,8 @@ public function validateImport()
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateUpdateAll()
     {
@@ -73,6 +75,8 @@ public function validateUpdateAll()
 
     /**
      * Imports options.
+     *
+     * @return void
      */
     public function import()
     {
@@ -82,6 +86,8 @@ public function import()
 
     /**
      * Updates the value of all given options.
+     *
+     * @return void
      */
     public function updateAll()
     {
@@ -92,7 +98,8 @@ public function updateAll()
     /**
      * Validates the basic SMTP connection parameters.
      *
-     * @throws      UserInputException
+     * @return void
+     * @throws UserInputException
      */
     public function validateEmailSmtpTest()
     {
@@ -114,7 +121,7 @@ public function validateEmailSmtpTest()
     /**
      * Runs a simple test of the SMTP connection.
      *
-     * @return      string[]
+     * @return array{validationResult: string}
      */
     public function emailSmtpTest()
     {
@@ -129,6 +136,9 @@ public function emailSmtpTest()
         return ['validationResult' => $smtp->testConnection()];
     }
 
+    /**
+     * @return void
+     */
     public function validateGenerateRewriteRules()
     {
         WCF::getSession()->checkPermissions(['admin.configuration.canEditOption']);
diff --git a/wcfsetup/install/files/lib/data/option/OptionEditor.class.php b/wcfsetup/install/files/lib/data/option/OptionEditor.class.php
index a5fbf0f13d4..8b48d8c182d 100644
--- a/wcfsetup/install/files/lib/data/option/OptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/option/OptionEditor.class.php
@@ -19,9 +19,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Option      create(array $parameters = [])
- * @method      Option      getDecoratedObject()
  * @mixin       Option
+ * @extends DatabaseObjectEditor<Option>
+ * @implements IEditableCachedObject<Option>
  */
 class OptionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -39,7 +39,8 @@ class OptionEditor extends DatabaseObjectEditor implements IEditableCachedObject
     /**
      * Imports the given options.
      *
-     * @param array $options name to value
+     * @param array<string, string|int|float> $options name to value
+     * @return void
      */
     public static function import(array $options)
     {
@@ -63,7 +64,8 @@ public static function import(array $options)
     /**
      * Updates the values of the given options.
      *
-     * @param array $options id to value
+     * @param array<int, string|int|float> $options id to value
+     * @return void
      */
     public static function updateAll(array $options)
     {
@@ -137,6 +139,8 @@ public static function resetCache()
 
     /**
      * Rebuilds the option file.
+     *
+     * @return void
      */
     public static function rebuild()
     {
diff --git a/wcfsetup/install/files/lib/data/option/OptionList.class.php b/wcfsetup/install/files/lib/data/option/OptionList.class.php
index 8487748ed50..73cdd78e46e 100644
--- a/wcfsetup/install/files/lib/data/option/OptionList.class.php
+++ b/wcfsetup/install/files/lib/data/option/OptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Option      current()
- * @method  Option[]    getObjects()
- * @method  Option|null getSingleObject()
- * @method  Option|null search($objectID)
- * @property    Option[] $objects
+ * @extends DatabaseObjectList<Option>
  */
 class OptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/option/category/OptionCategoryAction.class.php b/wcfsetup/install/files/lib/data/option/category/OptionCategoryAction.class.php
index 41ee26c01d1..e91ab3c6542 100644
--- a/wcfsetup/install/files/lib/data/option/category/OptionCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/option/category/OptionCategoryAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  OptionCategory      create()
- * @method  OptionCategoryEditor[]  getObjects()
- * @method  OptionCategoryEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<OptionCategory, OptionCategoryEditor>
  */
 class OptionCategoryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/option/category/OptionCategoryEditor.class.php b/wcfsetup/install/files/lib/data/option/category/OptionCategoryEditor.class.php
index f5b12a3c0da..c1dcbbaefd5 100644
--- a/wcfsetup/install/files/lib/data/option/category/OptionCategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/option/category/OptionCategoryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static OptionCategory      create(array $parameters = [])
- * @method      OptionCategory      getDecoratedObject()
  * @mixin       OptionCategory
+ * @extends DatabaseObjectEditor<OptionCategory>
  */
 class OptionCategoryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/option/category/OptionCategoryList.class.php b/wcfsetup/install/files/lib/data/option/category/OptionCategoryList.class.php
index 53720680603..76ef2831aac 100644
--- a/wcfsetup/install/files/lib/data/option/category/OptionCategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/option/category/OptionCategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  OptionCategory      current()
- * @method  OptionCategory[]    getObjects()
- * @method  OptionCategory|null getSingleObject()
- * @method  OptionCategory|null search($objectID)
- * @property    OptionCategory[] $objects
+ * @extends DatabaseObjectList<OptionCategory>
  */
 class OptionCategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/I18nPackageList.class.php b/wcfsetup/install/files/lib/data/package/I18nPackageList.class.php
index e9bd0249659..1213a21a619 100644
--- a/wcfsetup/install/files/lib/data/package/I18nPackageList.class.php
+++ b/wcfsetup/install/files/lib/data/package/I18nPackageList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method      Package       current()
- * @method      Package[]     getObjects()
- * @method      Package|null  getSingleObject()
- * @method      Package|null  search($objectID)
- * @property    Package[]     $objects
+ * @extends I18nDatabaseObjectList<Package>
  */
 class I18nPackageList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/Package.class.php b/wcfsetup/install/files/lib/data/package/Package.class.php
index 6af985aaacc..0a5530e21c2 100644
--- a/wcfsetup/install/files/lib/data/package/Package.class.php
+++ b/wcfsetup/install/files/lib/data/package/Package.class.php
@@ -73,7 +73,7 @@ class Package extends DatabaseObject implements ILinkableObject, IRouteControlle
 
     /**
      * package requirements
-     * @var array
+     * @var array<int, int[]>
      */
     protected static $requirements;
 
@@ -263,6 +263,7 @@ public function getDependentPackages()
      * DO NOT call this method outside the package installation!
      *
      * @param string $packageVersion
+     * @return void
      */
     public function setPackageVersion($packageVersion)
     {
@@ -282,6 +283,8 @@ public function getAbsolutePackageDir()
 
     /**
      * Loads package requirements.
+     *
+     * @return void
      */
     protected static function loadRequirements()
     {
@@ -431,6 +434,7 @@ private static function formatVersionForCompare(string $version): string
      * Writes the config.inc.php for an application.
      *
      * @param int $packageID
+     * @return void
      */
     public static function writeConfigFile($packageID)
     {
diff --git a/wcfsetup/install/files/lib/data/package/PackageAction.class.php b/wcfsetup/install/files/lib/data/package/PackageAction.class.php
index 7045b4356d6..a17ec72f3d2 100644
--- a/wcfsetup/install/files/lib/data/package/PackageAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/PackageAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Package         create()
- * @method  PackageEditor[]     getObjects()
- * @method  PackageEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Package, PackageEditor>
  */
 class PackageAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/package/PackageEditor.class.php b/wcfsetup/install/files/lib/data/package/PackageEditor.class.php
index 1c4699a66fe..db9c6fb0871 100644
--- a/wcfsetup/install/files/lib/data/package/PackageEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/PackageEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Package     create(array $parameters = [])
- * @method      Package     getDecoratedObject()
  * @mixin       Package
+ * @extends DatabaseObjectEditor<Package>
+ * @implements IEditableCachedObject<Package>
  */
 class PackageEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/package/PackageList.class.php b/wcfsetup/install/files/lib/data/package/PackageList.class.php
index 971c402ae32..106d865f5ee 100644
--- a/wcfsetup/install/files/lib/data/package/PackageList.class.php
+++ b/wcfsetup/install/files/lib/data/package/PackageList.class.php
@@ -12,11 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Package     current()
- * @method  Package[]   getObjects()
- * @method  Package|null    getSingleObject()
- * @method  Package|null    search($objectID)
- * @property    Package[] $objects
+ * @extends DatabaseObjectList<Package>
  */
 class PackageList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginAction.class.php b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginAction.class.php
index b5b4350758d..f2bddb45610 100644
--- a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginAction.class.php
@@ -28,9 +28,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageInstallationPlugin       create()
- * @method  PackageInstallationPluginEditor[]   getObjects()
- * @method  PackageInstallationPluginEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PackageInstallationPlugin, PackageInstallationPluginEditor>
  */
 class PackageInstallationPluginAction extends AbstractDatabaseObjectAction
 {
@@ -62,8 +60,9 @@ class PackageInstallationPluginAction extends AbstractDatabaseObjectAction
     /**
      * Validates parameters to invoke a single PIP.
      *
-     * @throws      PermissionDeniedException
-     * @throws      UserInputException
+     * @return void
+     * @throws PermissionDeniedException
+     * @throws UserInputException
      */
     public function validateInvoke()
     {
diff --git a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginEditor.class.php b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginEditor.class.php
index 5dbb1378487..f12c2bb3436 100644
--- a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PackageInstallationPlugin   create(array $parameters = [])
- * @method      PackageInstallationPlugin   getDecoratedObject()
  * @mixin       PackageInstallationPlugin
+ * @extends DatabaseObjectEditor<PackageInstallationPlugin>
  */
 class PackageInstallationPluginEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginList.class.php b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginList.class.php
index 9550a671a7f..31b749241d8 100644
--- a/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginList.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/plugin/PackageInstallationPluginList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageInstallationPlugin       current()
- * @method  PackageInstallationPlugin[]     getObjects()
- * @method  PackageInstallationPlugin|null      getSingleObject()
- * @method  PackageInstallationPlugin|null      search($objectID)
- * @property    PackageInstallationPlugin[] $objects
+ * @extends DatabaseObjectList<PackageInstallationPlugin>
  */
 class PackageInstallationPluginList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueAction.class.php b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueAction.class.php
index 927c639f563..91b48bbf919 100644
--- a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueAction.class.php
@@ -16,9 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageInstallationQueue        create()
- * @method  PackageInstallationQueueEditor[]    getObjects()
- * @method  PackageInstallationQueueEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PackageInstallationQueue, PackageInstallationQueueEditor>
  */
 class PackageInstallationQueueAction extends AbstractDatabaseObjectAction
 {
@@ -46,6 +44,8 @@ class PackageInstallationQueueAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates the 'cancelInstallation' action.
+     *
+     * @return void
      */
     public function validateCancelInstallation()
     {
@@ -65,6 +65,8 @@ public function validateCancelInstallation()
 
     /**
      * Cancels a certain installation.
+     *
+     * @return array{url: string}
      */
     public function cancelInstallation()
     {
diff --git a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueEditor.class.php b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueEditor.class.php
index 11c228b1c40..3ffb887930f 100644
--- a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PackageInstallationQueue    create(array $parameters = [])
- * @method      PackageInstallationQueue    getDecoratedObject()
  * @mixin       PackageInstallationQueue
+ * @extends DatabaseObjectEditor<PackageInstallationQueue>
  */
 class PackageInstallationQueueEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueList.class.php b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueList.class.php
index d43c9f3fb10..4865ad87d0d 100644
--- a/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueList.class.php
+++ b/wcfsetup/install/files/lib/data/package/installation/queue/PackageInstallationQueueList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageInstallationQueue        current()
- * @method  PackageInstallationQueue[]      getObjects()
- * @method  PackageInstallationQueue|null       getSingleObject()
- * @method  PackageInstallationQueue|null       search($objectID)
- * @property    PackageInstallationQueue[] $objects
+ * @extends DatabaseObjectList<PackageInstallationQueue>
  */
 class PackageInstallationQueueList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/PackageUpdateAction.class.php b/wcfsetup/install/files/lib/data/package/update/PackageUpdateAction.class.php
index 545e09b14f2..60342d96edd 100644
--- a/wcfsetup/install/files/lib/data/package/update/PackageUpdateAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/PackageUpdateAction.class.php
@@ -26,9 +26,17 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdate       create()
- * @method  PackageUpdateEditor[]   getObjects()
- * @method  PackageUpdateEditor getSingleObject()
+ * @phpstan-type QueueEntry array{
+ *  template: string,
+ *  type: 'authorizationRequired',
+ * }|array{
+ *  template: string,
+ *  type: 'conflict',
+ * }|array{
+ *  queueID: int,
+ *  type: 'queue',
+ * }
+ * @extends AbstractDatabaseObjectAction<PackageUpdate, PackageUpdateEditor>
  */
 class PackageUpdateAction extends AbstractDatabaseObjectAction
 {
@@ -50,6 +58,8 @@ class PackageUpdateAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates parameters to search for installable packages.
+     *
+     * @return void
      */
     public function validateSearch()
     {
@@ -61,7 +71,7 @@ public function validateSearch()
     /**
      * Returns a result list of a search for installable packages.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function search()
     {
@@ -270,7 +280,7 @@ static function ($packageUpdateServerID) use ($trustedServerIDs) {
      * @param string|null $minVersion
      * @param string[] $installedPackages
      * @param string[] $excludedPackagesOfInstalledPackages
-     * @return      string[][]
+     * @return string[][]
      */
     protected function canInstall(
         $packageUpdateID,
@@ -496,8 +506,8 @@ protected function canInstall(
      * Returns a result list for a previous search.
      *
      * @param PackageUpdateServer[] $updateServers
-     * @param array $updateData
-     * @return  array
+     * @param mixed[] $updateData
+     * @return array{count: int, template: string}
      */
     protected function getResultList(array $updateServers, array $updateData)
     {
@@ -578,6 +588,8 @@ protected function getResultList(array $updateServers, array $updateData)
 
     /**
      * Validates permissions to search for updates.
+     *
+     * @return void
      */
     public function validateSearchForUpdates()
     {
@@ -593,7 +605,7 @@ public function validateSearchForUpdates()
     /**
      * Searches for updates.
      *
-     * @return  array
+     * @return array{url: string}
      */
     public function searchForUpdates()
     {
@@ -612,6 +624,8 @@ public function searchForUpdates()
 
     /**
      * Validates parameters to perform a system update.
+     *
+     * @return void
      */
     public function validatePrepareUpdate()
     {
@@ -657,7 +671,7 @@ public function validatePrepareUpdate()
     /**
      * Prepares a system update.
      *
-     * @return  array
+     * @return QueueEntry
      */
     public function prepareUpdate()
     {
@@ -666,6 +680,8 @@ public function prepareUpdate()
 
     /**
      * Validates parameters to prepare a package installation.
+     *
+     * @return void
      */
     public function validatePrepareInstallation()
     {
@@ -695,13 +711,16 @@ public function validatePrepareInstallation()
     /**
      * Prepares a package installation.
      *
-     * @return  array
+     * @return QueueEntry
      */
     public function prepareInstallation()
     {
         return $this->createQueue('install');
     }
 
+    /**
+     * @return void
+     */
     public function validateRefreshDatabase()
     {
         WCF::getSession()->checkPermissions(['admin.configuration.package.canInstallPackage']);
@@ -713,6 +732,9 @@ public function validateRefreshDatabase()
         }
     }
 
+    /**
+     * @return void
+     */
     public function refreshDatabase()
     {
         PackageUpdateDispatcher::getInstance()->refreshPackageDatabase();
@@ -722,8 +744,8 @@ public function refreshDatabase()
      * Creates a new package installation queue.
      *
      * @param string $queueType
-     * @return  array
-     * @throws  SystemException
+     * @return QueueEntry
+     * @throws SystemException
      */
     protected function createQueue($queueType)
     {
diff --git a/wcfsetup/install/files/lib/data/package/update/PackageUpdateEditor.class.php b/wcfsetup/install/files/lib/data/package/update/PackageUpdateEditor.class.php
index ccad26b3ddb..34c2630b889 100644
--- a/wcfsetup/install/files/lib/data/package/update/PackageUpdateEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/PackageUpdateEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PackageUpdate   create(array $parameters = [])
- * @method      PackageUpdate   getDecoratedObject()
  * @mixin       PackageUpdate
+ * @extends DatabaseObjectEditor<PackageUpdate>
  */
 class PackageUpdateEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/PackageUpdateList.class.php b/wcfsetup/install/files/lib/data/package/update/PackageUpdateList.class.php
index e88a9c349e1..1addc389c1f 100644
--- a/wcfsetup/install/files/lib/data/package/update/PackageUpdateList.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/PackageUpdateList.class.php
@@ -12,11 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdate       current()
- * @method  PackageUpdate[]     getObjects()
- * @method  PackageUpdate|null  getSingleObject()
- * @method  PackageUpdate|null  search($objectID)
- * @property    PackageUpdate[] $objects
+ * @extends DatabaseObjectList<PackageUpdate>
  */
 class PackageUpdateList extends DatabaseObjectList
 {
@@ -27,6 +23,7 @@ class PackageUpdateList extends DatabaseObjectList
 
     /**
      * @inheritDoc
+     * @param bool $useSqlOr
      */
     public function __construct($useSqlOr = false)
     {
diff --git a/wcfsetup/install/files/lib/data/package/update/ViewablePackageUpdate.class.php b/wcfsetup/install/files/lib/data/package/update/ViewablePackageUpdate.class.php
index 2810fccdc89..12dfaf6c924 100644
--- a/wcfsetup/install/files/lib/data/package/update/ViewablePackageUpdate.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/ViewablePackageUpdate.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdate   getDecoratedObject()
  * @mixin   PackageUpdate
+ * @extends DatabaseObjectDecorator<PackageUpdate>
  */
 class ViewablePackageUpdate extends DatabaseObjectDecorator
 {
@@ -43,7 +43,7 @@ class ViewablePackageUpdate extends DatabaseObjectDecorator
     /**
      * Sets latest accessible package update version object.
      *
-     * @param PackageUpdateVersion $latestVersion
+     * @return void
      */
     public function setAccessibleVersion(PackageUpdateVersion $latestVersion)
     {
@@ -53,7 +53,7 @@ public function setAccessibleVersion(PackageUpdateVersion $latestVersion)
     /**
      * Sets latest package update version object.
      *
-     * @param PackageUpdateVersion $latestVersion
+     * @return void
      */
     public function setLatestVersion(PackageUpdateVersion $latestVersion)
     {
@@ -63,7 +63,7 @@ public function setLatestVersion(PackageUpdateVersion $latestVersion)
     /**
      * Returns latest accessible package update version object.
      *
-     * @return  PackageUpdateVersion
+     * @return PackageUpdateVersion
      */
     public function getAccessibleVersion()
     {
@@ -73,7 +73,7 @@ public function getAccessibleVersion()
     /**
      * Returns latest package update version object.
      *
-     * @return  PackageUpdateVersion
+     * @return PackageUpdateVersion
      */
     public function getLatestVersion()
     {
@@ -81,7 +81,7 @@ public function getLatestVersion()
     }
 
     /**
-     * @param PackageUpdateServer $updateServer
+     * @return void
      * @since 5.2
      */
     public function setUpdateServer(PackageUpdateServer $updateServer)
diff --git a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServer.class.php b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServer.class.php
index 94b00d56c0b..ea77f55499c 100644
--- a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServer.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServer.class.php
@@ -37,7 +37,7 @@ class PackageUpdateServer extends DatabaseObject
 
     /**
      * API meta data
-     * @var array
+     * @var mixed[]
      */
     protected $metaData = [];
 
@@ -45,6 +45,8 @@ class PackageUpdateServer extends DatabaseObject
      * Restricts the package server selection to include only
      * official package servers in case a secure download is
      * requested.
+     *
+     * @var bool
      */
     private static $secureMode = false;
 
@@ -170,6 +172,7 @@ final public static function enableSecureMode(): void
     }
 
     /**
+     * @param string $serverURL
      * @deprecated 6.0 This method was only used in PackageUpdateServerAddForm.
      */
     public static function isValidServerURL($serverURL): bool
@@ -305,7 +308,7 @@ public function getDownloadURL(): string
     /**
      * Returns API meta data.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getMetaData()
     {
diff --git a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerAction.class.php b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerAction.class.php
index a17659ad233..26b510a0b92 100644
--- a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdateServer     create()
- * @method  PackageUpdateServerEditor[] getObjects()
- * @method  PackageUpdateServerEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PackageUpdateServer, PackageUpdateServerEditor>
  */
 class PackageUpdateServerAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerEditor.class.php b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerEditor.class.php
index aa46781e1ee..62e62fd8c57 100644
--- a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PackageUpdateServer create(array $parameters = [])
- * @method      PackageUpdateServer getDecoratedObject()
  * @mixin       PackageUpdateServer
+ * @extends DatabaseObjectEditor<PackageUpdateServer>
+ * @implements IEditableCachedObject<PackageUpdateServer>
  */
 class PackageUpdateServerEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerList.class.php b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerList.class.php
index fa4ca02247d..00249eeb2b6 100644
--- a/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerList.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/server/PackageUpdateServerList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdateServer     current()
- * @method  PackageUpdateServer[]       getObjects()
- * @method  PackageUpdateServer|null    getSingleObject()
- * @method  PackageUpdateServer|null    search($objectID)
- * @property    PackageUpdateServer[] $objects
+ * @extends DatabaseObjectList<PackageUpdateServer>
  */
 class PackageUpdateServerList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionAction.class.php b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionAction.class.php
index e84bae34b04..8611b79707f 100644
--- a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionAction.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdateVersion        create()
- * @method  PackageUpdateVersionEditor[]    getObjects()
- * @method  PackageUpdateVersionEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PackageUpdateVersion, PackageUpdateVersionEditor>
  */
 class PackageUpdateVersionAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionEditor.class.php b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionEditor.class.php
index d8ccd9374da..b5fce4a2c16 100644
--- a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PackageUpdateVersion    create(array $parameters = [])
- * @method      PackageUpdateVersion    getDecoratedObject()
  * @mixin       PackageUpdateVersion
+ * @extends DatabaseObjectEditor<PackageUpdateVersion>
  */
 class PackageUpdateVersionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionList.class.php b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionList.class.php
index 84f61b98c90..a5579812c45 100644
--- a/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionList.class.php
+++ b/wcfsetup/install/files/lib/data/package/update/version/PackageUpdateVersionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PackageUpdateVersion        current()
- * @method  PackageUpdateVersion[]      getObjects()
- * @method  PackageUpdateVersion|null   getSingleObject()
- * @method  PackageUpdateVersion|null   search($objectID)
- * @property    PackageUpdateVersion[] $objects
+ * @extends DatabaseObjectList<PackageUpdateVersion>
  */
 class PackageUpdateVersionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/page/Page.class.php b/wcfsetup/install/files/lib/data/page/Page.class.php
index cca3377c968..e67e475c187 100644
--- a/wcfsetup/install/files/lib/data/page/Page.class.php
+++ b/wcfsetup/install/files/lib/data/page/Page.class.php
@@ -276,6 +276,7 @@ public function isAccessible(?User $user = null)
     }
 
     /**
+     * @return void
      * @deprecated 6.0 The landing page is a property of the 'wcf' app.
      */
     public function setAsLandingPage()
diff --git a/wcfsetup/install/files/lib/data/page/PageAction.class.php b/wcfsetup/install/files/lib/data/page/PageAction.class.php
index 014edbadbae..dcee84d960c 100644
--- a/wcfsetup/install/files/lib/data/page/PageAction.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageAction.class.php
@@ -29,8 +29,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  PageEditor[]    getObjects()
- * @method  PageEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Page, PageEditor>
  */
 class PageAction extends AbstractDatabaseObjectAction implements ISearchAction, ISortableAction, IToggleAction
 {
@@ -345,6 +344,8 @@ public function getSearchResultList()
 
     /**
      * Validates parameters to search for a page by its internal name.
+     *
+     * @return void
      */
     public function validateSearch()
     {
@@ -354,7 +355,11 @@ public function validateSearch()
     /**
      * Searches for a page by its internal name.
      *
-     * @return      array   list of matching pages
+     * @return list<array{
+     *  displayLink: string,
+     *  name: string,
+     *  pageID: int,
+     * }> list of matching pages
      */
     public function search()
     {
@@ -503,6 +508,8 @@ public function updatePosition()
 
     /**
      * Validates parameters to reset the custom box positions for provided page.
+     *
+     * @return void
      */
     public function validateResetPosition()
     {
@@ -513,6 +520,8 @@ public function validateResetPosition()
 
     /**
      * Resets the custom box positions for provided page.
+     *
+     * @return void
      */
     public function resetPosition()
     {
diff --git a/wcfsetup/install/files/lib/data/page/PageCache.class.php b/wcfsetup/install/files/lib/data/page/PageCache.class.php
index 331c4aa1372..c5f53a5c7ac 100644
--- a/wcfsetup/install/files/lib/data/page/PageCache.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageCache.class.php
@@ -17,8 +17,14 @@
 class PageCache extends SingletonFactory
 {
     /**
-     * page cache
-     * @var array
+     * @var array{
+     *  identifier: array<string, int>,
+     *  controller: array<string, int>,
+     *  pages: array<int, Page>,
+     *  pageTitles: array<int, array<int, string>>,
+     *  landingPage: Page,
+     *  pageMetaDescriptions: array<int, array<int, string>>,
+     * }
      */
     protected $cache;
 
diff --git a/wcfsetup/install/files/lib/data/page/PageEditor.class.php b/wcfsetup/install/files/lib/data/page/PageEditor.class.php
index de5c97ab3d4..96f763a47dd 100644
--- a/wcfsetup/install/files/lib/data/page/PageEditor.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageEditor.class.php
@@ -20,9 +20,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static Page    create(array $parameters = [])
- * @method      Page    getDecoratedObject()
  * @mixin       Page
+ * @extends DatabaseObjectEditor<Page>
+ * @implements IEditableCachedObject<Page>
  */
 class PageEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -36,6 +36,7 @@ class PageEditor extends DatabaseObjectEditor implements IEditableCachedObject
      *
      * @param int $languageID language id or `null`
      * @param string $content template content
+     * @return void
      */
     public function updateTemplate($languageID, $content)
     {
diff --git a/wcfsetup/install/files/lib/data/page/PageList.class.php b/wcfsetup/install/files/lib/data/page/PageList.class.php
index f4b2e057734..310109312e3 100644
--- a/wcfsetup/install/files/lib/data/page/PageList.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Page        current()
- * @method  Page[]      getObjects()
- * @method  Page|null   getSingleObject()
- * @method  Page|null   search($objectID)
- * @property    Page[] $objects
+ * @extends DatabaseObjectList<Page>
  */
 class PageList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/page/PageNode.class.php b/wcfsetup/install/files/lib/data/page/PageNode.class.php
index 0a66552abc9..0d14ed12922 100644
--- a/wcfsetup/install/files/lib/data/page/PageNode.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageNode.class.php
@@ -14,8 +14,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Page    getDecoratedObject()
  * @mixin   Page
+ * @extends DatabaseObjectDecorator<Page>
  */
 class PageNode extends DatabaseObjectDecorator implements IObjectTreeNode
 {
diff --git a/wcfsetup/install/files/lib/data/page/PageNodeTree.class.php b/wcfsetup/install/files/lib/data/page/PageNodeTree.class.php
index f4b758d1cf3..c69cada32f4 100644
--- a/wcfsetup/install/files/lib/data/page/PageNodeTree.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageNodeTree.class.php
@@ -110,7 +110,7 @@ public function getNodeTree()
     /**
      * Returns the iterable node list.
      *
-     * @return  \RecursiveIteratorIterator
+     * @return  \RecursiveIteratorIterator<PageNode>
      */
     public function getNodeList()
     {
diff --git a/wcfsetup/install/files/lib/data/page/PageVersionTracker.class.php b/wcfsetup/install/files/lib/data/page/PageVersionTracker.class.php
index 867cdc79b60..63702c2f7ca 100644
--- a/wcfsetup/install/files/lib/data/page/PageVersionTracker.class.php
+++ b/wcfsetup/install/files/lib/data/page/PageVersionTracker.class.php
@@ -15,8 +15,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  Page    getDecoratedObject()
  * @mixin   Page
+ * @extends DatabaseObjectDecorator<Page>
  */
 class PageVersionTracker extends DatabaseObjectDecorator implements IVersionTrackerObject
 {
@@ -43,6 +43,7 @@ public function getObjectID()
      * Adds an page content object as child.
      *
      * @param PageContent $content page content object
+     * @return void
      */
     public function addContent(PageContent $content)
     {
@@ -53,6 +54,7 @@ public function addContent(PageContent $content)
      * Sets the list of page content objects.
      *
      * @param PageContent[] $content page content objects
+     * @return void
      */
     public function setContent(array $content)
     {
@@ -62,7 +64,7 @@ public function setContent(array $content)
     /**
      * Returns the list of stored page content objects.
      *
-     * @return      PageContent[]   stored page content objects
+     * @return PageContent[]   stored page content objects
      */
     public function getContent()
     {
diff --git a/wcfsetup/install/files/lib/data/page/content/PageContentAction.class.php b/wcfsetup/install/files/lib/data/page/content/PageContentAction.class.php
index b399dd29390..92c786a8352 100644
--- a/wcfsetup/install/files/lib/data/page/content/PageContentAction.class.php
+++ b/wcfsetup/install/files/lib/data/page/content/PageContentAction.class.php
@@ -12,8 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  PageContentEditor[] getObjects()
- * @method  PageContentEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PageContent, PageContentEditor>
  */
 class PageContentAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/page/content/PageContentEditor.class.php b/wcfsetup/install/files/lib/data/page/content/PageContentEditor.class.php
index 875554f2866..16db34e681e 100644
--- a/wcfsetup/install/files/lib/data/page/content/PageContentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/page/content/PageContentEditor.class.php
@@ -12,9 +12,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method static PageContent create(array $parameters = [])
- * @method      PageContent getDecoratedObject()
  * @mixin       PageContent
+ * @extends DatabaseObjectEditor<PageContent>
  */
 class PageContentEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/page/content/PageContentList.class.php b/wcfsetup/install/files/lib/data/page/content/PageContentList.class.php
index fd7b32a6398..c32dae3f803 100644
--- a/wcfsetup/install/files/lib/data/page/content/PageContentList.class.php
+++ b/wcfsetup/install/files/lib/data/page/content/PageContentList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  PageContent     current()
- * @method  PageContent[]           getObjects()
- * @method  PageContent|null    getSingleObject()
- * @method  PageContent|null    search($objectID)
- * @property    PageContent[] $objects
+ * @extends DatabaseObjectList<PageContent>
  */
 class PageContentList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/page/content/SearchResultPageContent.class.php b/wcfsetup/install/files/lib/data/page/content/SearchResultPageContent.class.php
index 6728e64259b..5e5c8f1f49d 100644
--- a/wcfsetup/install/files/lib/data/page/content/SearchResultPageContent.class.php
+++ b/wcfsetup/install/files/lib/data/page/content/SearchResultPageContent.class.php
@@ -16,8 +16,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  PageContent getDecoratedObject()
  * @mixin   PageContent
+ * @extends DatabaseObjectDecorator<PageContent>
  */
 class SearchResultPageContent extends DatabaseObjectDecorator implements ISearchResultObject
 {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/I18nPaidSubscriptionList.class.php b/wcfsetup/install/files/lib/data/paid/subscription/I18nPaidSubscriptionList.class.php
index ddb2dccfea3..4fef56c84a5 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/I18nPaidSubscriptionList.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/I18nPaidSubscriptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscription    current()
- * @method  PaidSubscription[]  getObjects()
- * @method  PaidSubscription|null   getSingleObject()
- * @method  PaidSubscription|null   search($objectID)
- * @property    PaidSubscription[] $objects
+ * @extends I18nDatabaseObjectList<PaidSubscription>
  */
 class I18nPaidSubscriptionList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionAction.class.php b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionAction.class.php
index 6b08682d070..1936ef14986 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionAction.class.php
@@ -13,9 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscriptionEditor[]    getObjects()
- * @method  PaidSubscriptionEditor      getSingleObject()
- * @property PaidSubscriptionEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<PaidSubscription, PaidSubscriptionEditor>
  */
 class PaidSubscriptionAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionEditor.class.php b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionEditor.class.php
index e960759384c..4b38b549bb3 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionEditor.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PaidSubscription    create(array $parameters = [])
- * @method      PaidSubscription    getDecoratedObject()
  * @mixin       PaidSubscription
+ * @extends DatabaseObjectEditor<PaidSubscription>
+ * @implements IEditableCachedObject<PaidSubscription>
  */
 class PaidSubscriptionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -29,6 +29,7 @@ class PaidSubscriptionEditor extends DatabaseObjectEditor implements IEditableCa
      * Sets the show order of the subscription.
      *
      * @param int $showOrder
+     * @return void
      */
     public function setShowOrder($showOrder = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionList.class.php b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionList.class.php
index 1d138212b26..10a53050cc3 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionList.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/PaidSubscriptionList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscription    current()
- * @method  PaidSubscription[]  getObjects()
- * @method  PaidSubscription|null   getSingleObject()
- * @method  PaidSubscription|null   search($objectID)
- * @property    PaidSubscription[] $objects
+ * @extends DatabaseObjectList<PaidSubscription>
  */
-class PaidSubscriptionList extends DatabaseObjectList
-{
-}
+class PaidSubscriptionList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLog.class.php b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLog.class.php
index acb0fed9938..4037af5cd72 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLog.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLog.class.php
@@ -54,7 +54,7 @@ public function getPaymentMethodName()
     /**
      * Returns transaction details.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getTransactionDetails()
     {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogAction.class.php b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogAction.class.php
index f03f5f0ee53..364e7490644 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogAction.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogAction.class.php
@@ -11,10 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscriptionTransactionLog      create()
- * @method  PaidSubscriptionTransactionLogEditor[]  getObjects()
- * @method  PaidSubscriptionTransactionLogEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PaidSubscriptionTransactionLog, PaidSubscriptionTransactionLogEditor>
  */
-class PaidSubscriptionTransactionLogAction extends AbstractDatabaseObjectAction
-{
-}
+class PaidSubscriptionTransactionLogAction extends AbstractDatabaseObjectAction {}
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogEditor.class.php b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogEditor.class.php
index 37ee8b07d14..3dc2a745732 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogEditor.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PaidSubscriptionTransactionLog      create(array $parameters = [])
- * @method      PaidSubscriptionTransactionLog      getDecoratedObject()
  * @mixin       PaidSubscriptionTransactionLog
+ * @extends DatabaseObjectEditor<PaidSubscriptionTransactionLog>
  */
 class PaidSubscriptionTransactionLogEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogList.class.php b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogList.class.php
index fffbcdec0e8..3ed40779b78 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogList.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/transaction/log/PaidSubscriptionTransactionLogList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscriptionTransactionLog      current()
- * @method  PaidSubscriptionTransactionLog[]    getObjects()
- * @method  PaidSubscriptionTransactionLog|null getSingleObject()
- * @method  PaidSubscriptionTransactionLog|null search($objectID)
- * @property    PaidSubscriptionTransactionLog[] $objects
+ * @extends DatabaseObjectList<PaidSubscriptionTransactionLog>
  */
-class PaidSubscriptionTransactionLogList extends DatabaseObjectList
-{
-}
+class PaidSubscriptionTransactionLogList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUser.class.php b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUser.class.php
index b7128a66776..605844ab49a 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUser.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUser.class.php
@@ -58,7 +58,7 @@ public function getSubscription()
     /**
      * Sets the paid subscription object.
      *
-     * @param PaidSubscription $subscription
+     * @return void
      */
     public function setSubscription(PaidSubscription $subscription)
     {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserAction.class.php b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserAction.class.php
index a91463d45d9..0a4c33bea3f 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserAction.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserAction.class.php
@@ -17,8 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscriptionUserEditor[]    getObjects()
- * @method  PaidSubscriptionUserEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PaidSubscriptionUser, PaidSubscriptionUserEditor>
  */
 class PaidSubscriptionUserAction extends AbstractDatabaseObjectAction
 {
@@ -39,7 +38,6 @@ class PaidSubscriptionUserAction extends AbstractDatabaseObjectAction
 
     /**
      * @inheritDoc
-     * @return  PaidSubscriptionUser
      */
     public function create()
     {
@@ -62,7 +60,6 @@ public function create()
             $this->parameters['data']['isActive'] = 1;
         }
 
-        /** @var PaidSubscriptionUser $subscriptionUser */
         $subscriptionUser = parent::create();
 
         // update group memberships
@@ -92,6 +89,8 @@ public function validateCreate()
 
     /**
      * Extends an existing subscription.
+     *
+     * @return void
      */
     public function extend()
     {
@@ -138,6 +137,8 @@ public function delete()
 
     /**
      * Revokes an existing subscription.
+     *
+     * @return void
      */
     public function revoke()
     {
@@ -172,6 +173,8 @@ public function revoke()
 
     /**
      * Validates the revoke action.
+     *
+     * @return void
      */
     public function validateRevoke()
     {
@@ -188,6 +191,8 @@ public function validateRevoke()
 
     /**
      * Restores an existing subscription.
+     *
+     * @return void
      */
     public function restore()
     {
@@ -206,6 +211,8 @@ public function restore()
 
     /**
      * Validates the restore action.
+     *
+     * @return void
      */
     public function validateRestore()
     {
@@ -222,6 +229,8 @@ public function validateRestore()
 
     /**
      * Applies group memberships.
+     *
+     * @return void
      */
     public function addGroupMemberships()
     {
@@ -250,6 +259,8 @@ public function addGroupMemberships()
 
     /**
      * Removes group memberships.
+     *
+     * @return void
      */
     public function removeGroupMemberships()
     {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserEditor.class.php b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserEditor.class.php
index ddaa816e47a..bca1823625f 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserEditor.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PaidSubscriptionUser    create(array $parameters = [])
- * @method      PaidSubscriptionUser    getDecoratedObject()
  * @mixin       PaidSubscriptionUser
+ * @extends DatabaseObjectEditor<PaidSubscriptionUser>
  */
 class PaidSubscriptionUserEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserList.class.php b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserList.class.php
index c23bc4cf1b8..e88bebfc6f3 100644
--- a/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserList.class.php
+++ b/wcfsetup/install/files/lib/data/paid/subscription/user/PaidSubscriptionUserList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PaidSubscriptionUser        current()
- * @method  PaidSubscriptionUser[]      getObjects()
- * @method  PaidSubscriptionUser|null   getSingleObject()
- * @method  PaidSubscriptionUser|null   search($objectID)
- * @property    PaidSubscriptionUser[] $objects
+ * @extends DatabaseObjectList<PaidSubscriptionUser>
  */
-class PaidSubscriptionUserList extends DatabaseObjectList
-{
-}
+class PaidSubscriptionUserList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/poll/Poll.class.php b/wcfsetup/install/files/lib/data/poll/Poll.class.php
index 857b9e66d01..975522dc27d 100644
--- a/wcfsetup/install/files/lib/data/poll/Poll.class.php
+++ b/wcfsetup/install/files/lib/data/poll/Poll.class.php
@@ -51,7 +51,7 @@ class Poll extends DatabaseObject
     /**
      * Adds an option to current poll.
      *
-     * @param PollOption $option
+     * @return void
      */
     public function addOption(PollOption $option)
     {
@@ -69,7 +69,7 @@ public function addOption(PollOption $option)
      * Returns a list of poll options.
      *
      * @param bool $isResultDisplay
-     * @return  PollOption[]
+     * @return PollOption[]
      */
     public function getOptions($isResultDisplay = false)
     {
@@ -96,7 +96,7 @@ public function getOptions($isResultDisplay = false)
     /**
      * Returns true if current user is a participant.
      *
-     * @return  bool
+     * @return bool
      */
     public function isParticipant()
     {
@@ -107,6 +107,8 @@ public function isParticipant()
 
     /**
      * Loads associated options.
+     *
+     * @return void
      */
     protected function loadOptions()
     {
@@ -128,7 +130,7 @@ protected function loadOptions()
     /**
      * Returns true if poll is already finished.
      *
-     * @return  bool
+     * @return bool
      */
     public function isFinished()
     {
@@ -138,7 +140,7 @@ public function isFinished()
     /**
      * Returns true if current user can vote.
      *
-     * @return  bool
+     * @return bool
      */
     public function canVote()
     {
@@ -169,7 +171,7 @@ public function canVote()
     /**
      * Returns true if current user can see the result.
      *
-     * @return  bool
+     * @return bool
      */
     public function canSeeResult()
     {
@@ -183,7 +185,7 @@ public function canSeeResult()
     /**
      * Returns true if current user can view the participant list.
      *
-     * @return  bool
+     * @return bool
      */
     public function canViewParticipants()
     {
@@ -197,7 +199,7 @@ public function canViewParticipants()
     /**
      * Sets related object for this poll.
      *
-     * @param IPollObject $object
+     * @return void
      */
     public function setRelatedObject(IPollObject $object)
     {
@@ -207,7 +209,7 @@ public function setRelatedObject(IPollObject $object)
     /**
      * Returns related object.
      *
-     * @return  IPollObject
+     * @return IPollObject
      */
     public function getRelatedObject()
     {
diff --git a/wcfsetup/install/files/lib/data/poll/PollAction.class.php b/wcfsetup/install/files/lib/data/poll/PollAction.class.php
index 3c40651c7b6..36bf34d8365 100644
--- a/wcfsetup/install/files/lib/data/poll/PollAction.class.php
+++ b/wcfsetup/install/files/lib/data/poll/PollAction.class.php
@@ -20,9 +20,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PollEditor[]    getObjects()
- * @method  PollEditor  getSingleObject()
- * @property-read PollEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Poll, PollEditor>
  */
 class PollAction extends AbstractDatabaseObjectAction implements IGroupedUserListAction
 {
@@ -199,6 +197,13 @@ public function validateVote(): void
 
     /**
      * Executes a user's vote.
+     *
+     * @return array{
+     *  changeableVote: int,
+     *  totalVotes: int,
+     *  totalVotesTooltip: string,
+     *  template: string,
+     * }
      */
     public function vote()
     {
@@ -335,12 +340,11 @@ public function validateGetResultTemplate(): void
     }
 
     /**
+     * @return array{template: string}
      * @since  5.5
      */
     public function getResultTemplate(): array
     {
-        \assert($this->poll instanceof PollEditor);
-
         return [
             'template' => WCF::getTPL()->render('wcf', 'pollResult', [
                 'poll' => $this->poll->getDecoratedObject(),
@@ -368,6 +372,7 @@ public function validateGetVoteTemplate(): void
     }
 
     /**
+     * @return array{template: string}
      * @since  5.5
      */
     public function getVoteTemplate(): array
@@ -431,6 +436,8 @@ public function getGroupedUserList()
 
     /**
      * Copies a poll from one object id to another.
+     *
+     * @return array{pollID: ?int}
      */
     public function copy()
     {
diff --git a/wcfsetup/install/files/lib/data/poll/PollEditor.class.php b/wcfsetup/install/files/lib/data/poll/PollEditor.class.php
index 38b433d6c29..0efe10deb3f 100644
--- a/wcfsetup/install/files/lib/data/poll/PollEditor.class.php
+++ b/wcfsetup/install/files/lib/data/poll/PollEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Poll    create(array $parameters = [])
- * @method      Poll    getDecoratedObject()
  * @mixin       Poll
+ * @extends DatabaseObjectEditor<Poll>
  */
 class PollEditor extends DatabaseObjectEditor
 {
@@ -25,6 +24,8 @@ class PollEditor extends DatabaseObjectEditor
 
     /**
      * Calculates poll votes.
+     *
+     * @return void
      */
     public function calculateVotes()
     {
@@ -53,6 +54,8 @@ public function calculateVotes()
 
     /**
      * Increase votes by one.
+     *
+     * @return void
      */
     public function increaseVotes()
     {
diff --git a/wcfsetup/install/files/lib/data/poll/PollList.class.php b/wcfsetup/install/files/lib/data/poll/PollList.class.php
index fd80a5cedeb..79bc7cc89fc 100644
--- a/wcfsetup/install/files/lib/data/poll/PollList.class.php
+++ b/wcfsetup/install/files/lib/data/poll/PollList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Poll        current()
- * @method  Poll[]      getObjects()
- * @method  Poll|null   getSingleObject()
- * @method  Poll|null   search($objectID)
- * @property    Poll[] $objects
+ * @extends DatabaseObjectList<Poll>
  */
 class PollList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/poll/option/PollOptionAction.class.php b/wcfsetup/install/files/lib/data/poll/option/PollOptionAction.class.php
index bb6a56e863a..f595386d0cc 100644
--- a/wcfsetup/install/files/lib/data/poll/option/PollOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/poll/option/PollOptionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PollOption      create()
- * @method  PollOptionEditor[]  getObjects()
- * @method  PollOptionEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<PollOption, PollOptionEditor>
  */
 class PollOptionAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/poll/option/PollOptionEditor.class.php b/wcfsetup/install/files/lib/data/poll/option/PollOptionEditor.class.php
index 63519054de4..0b72882c679 100644
--- a/wcfsetup/install/files/lib/data/poll/option/PollOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/poll/option/PollOptionEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static PollOption  create(array $parameters = [])
- * @method      PollOption  getDecoratedObject()
  * @mixin       PollOption
+ * @extends DatabaseObjectEditor<PollOption>
  */
 class PollOptionEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/poll/option/PollOptionList.class.php b/wcfsetup/install/files/lib/data/poll/option/PollOptionList.class.php
index 3049940ed65..fd7225f82dd 100644
--- a/wcfsetup/install/files/lib/data/poll/option/PollOptionList.class.php
+++ b/wcfsetup/install/files/lib/data/poll/option/PollOptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PollOption      current()
- * @method  PollOption[]        getObjects()
- * @method  PollOption|null     getSingleObject()
- * @method  PollOption|null     search($objectID)
- * @property    PollOption[] $objects
+ * @extends DatabaseObjectList<PollOption>
  */
 class PollOptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/reaction/ReactionAction.class.php b/wcfsetup/install/files/lib/data/reaction/ReactionAction.class.php
index 54739a5b639..7486b318c91 100644
--- a/wcfsetup/install/files/lib/data/reaction/ReactionAction.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/ReactionAction.class.php
@@ -3,6 +3,7 @@
 namespace wcf\data\reaction;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
 use wcf\data\like\ILikeObjectTypeProvider;
 use wcf\data\like\IRestrictedLikeObjectTypeProvider;
 use wcf\data\like\Like;
@@ -34,9 +35,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method  Like        create()
- * @method  LikeEditor[]    getObjects()
- * @method  LikeEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Like, LikeEditor>
  */
 class ReactionAction extends AbstractDatabaseObjectAction
 {
@@ -64,7 +63,7 @@ class ReactionAction extends AbstractDatabaseObjectAction
 
     /**
      * like object type provider object
-     * @var ILikeObjectTypeProvider
+     * @var ILikeObjectTypeProvider<DatabaseObject>
      */
     public $objectTypeProvider;
 
@@ -76,6 +75,8 @@ class ReactionAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates parameters to fetch like details.
+     *
+     * @return void
      */
     public function validateGetReactionDetails()
     {
@@ -89,7 +90,7 @@ public function validateGetReactionDetails()
     /**
      * Returns like details.
      *
-     * @return  string[]
+     * @return array{template: string, title: string}
      */
     public function getReactionDetails()
     {
@@ -127,6 +128,8 @@ public function getReactionDetails()
 
     /**
      * Validates permissions for given object.
+     *
+     * @return void
      */
     protected function validateObjectParameters()
     {
@@ -157,7 +160,13 @@ protected function validateObjectParameters()
     /**
      * React on an given object with the given reactionType.
      *
-     * @return array
+     * @return array{
+     *  reactions: array<int, int>,
+     *  objectID: int,
+     *  objectType: string,
+     *  reactionTypeID: int,
+     *  reputationCount: int,
+     * }
      */
     public function react()
     {
@@ -179,6 +188,8 @@ public function react()
 
     /**
      * Validates the 'react' method.
+     *
+     * @return void
      */
     public function validateReact()
     {
@@ -228,6 +239,8 @@ public function validateReact()
 
     /**
      * Validates parameters to load reactions.
+     *
+     * @return void
      */
     public function validateLoad()
     {
@@ -254,7 +267,7 @@ public function validateLoad()
     /**
      * Loads a list of reactions.
      *
-     * @return  array
+     * @return array{lastLikeTime: int, template: string}|array{}
      */
     public function load()
     {
@@ -289,6 +302,8 @@ public function load()
 
     /**
      * Copies likes from one object id to another.
+     *
+     * @return void
      */
     public function copy()
     {
diff --git a/wcfsetup/install/files/lib/data/reaction/object/IReactionObject.class.php b/wcfsetup/install/files/lib/data/reaction/object/IReactionObject.class.php
index edc10fefc9b..ba019b8984d 100644
--- a/wcfsetup/install/files/lib/data/reaction/object/IReactionObject.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/object/IReactionObject.class.php
@@ -17,7 +17,7 @@ interface IReactionObject
     /**
      * Sends a notification for this reaction.
      *
-     * @param Like $like
+     * @return void
      */
     public function sendNotification(Like $like);
 }
diff --git a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeAction.class.php b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeAction.class.php
index 2620e615a51..0a9045aa489 100644
--- a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeAction.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeAction.class.php
@@ -20,8 +20,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method  ReactionTypeEditor[]        getObjects()
- * @method  ReactionTypeEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ReactionType, ReactionTypeEditor>
  */
 class ReactionTypeAction extends AbstractDatabaseObjectAction implements ISortableAction, IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeCache.class.php b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeCache.class.php
index 05ba678c9a9..8df74969f9d 100644
--- a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeCache.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeCache.class.php
@@ -33,7 +33,7 @@ protected function init()
      * Returns the reaction type with the given reactionTypeID.
      *
      * @param int $reactionTypeID
-     * @return  ReactionType|null
+     * @return ?ReactionType
      */
     public function getReactionTypeByID($reactionTypeID)
     {
@@ -44,7 +44,7 @@ public function getReactionTypeByID($reactionTypeID)
      * Returns the reaction types with the given reactionTypeIDs.
      *
      * @param int[] $reactionTypeIDs
-     * @return  ReactionType[]
+     * @return ReactionType[]
      */
     public function getReactionTypesByID(array $reactionTypeIDs)
     {
@@ -60,7 +60,7 @@ public function getReactionTypesByID(array $reactionTypeIDs)
     /**
      * Return all reaction types.
      *
-     * @return  ReactionType[]
+     * @return ReactionType[]
      */
     public function getReactionTypes()
     {
@@ -69,6 +69,8 @@ public function getReactionTypes()
 
     /**
      * Resets the cache for the trophies.
+     *
+     * @return void
      */
     public function clearCache()
     {
diff --git a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeEditor.class.php b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeEditor.class.php
index b11e5a39dba..1c067097b48 100644
--- a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeEditor.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeEditor.class.php
@@ -13,9 +13,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method      static ReactionType    create(array $parameters = [])
- * @method              ReactionType    getDecoratedObject()
- * @mixin                   ReactionType
+ * @mixin ReactionType
+ * @extends DatabaseObjectEditor<ReactionType>
+ * @implements IEditableCachedObject<ReactionType>
  */
 class ReactionTypeEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeList.class.php b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeList.class.php
index 5af5522e415..3bb3624f309 100644
--- a/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeList.class.php
+++ b/wcfsetup/install/files/lib/data/reaction/type/ReactionTypeList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method  ReactionType        current()
- * @method  ReactionType[]          getObjects()
- * @method  ReactionType|null   getSingleObject()
- * @method  ReactionType|null   search($objectID)
- * @property    ReactionType[] $objects
+ * @extends DatabaseObjectList<ReactionType>
  */
 class ReactionTypeList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/search/SearchAction.class.php b/wcfsetup/install/files/lib/data/search/SearchAction.class.php
index 37a065966c9..68123b4fd1b 100644
--- a/wcfsetup/install/files/lib/data/search/SearchAction.class.php
+++ b/wcfsetup/install/files/lib/data/search/SearchAction.class.php
@@ -19,9 +19,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Search      create()
- * @method  SearchEditor[]  getObjects()
- * @method  SearchEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Search, SearchEditor>
  */
 class SearchAction extends AbstractDatabaseObjectAction
 {
@@ -91,6 +89,14 @@ public function validateSearch(): void
     }
 
     /**
+     * @return array{
+     *  count: int,
+     *  title: string,
+     *  pages: int,
+     *  pageNo: int,
+     *  searchID: int,
+     *  template: string,
+     * }|array{count: int, title: string}
      * @since 5.5
      */
     public function search(): array
@@ -123,7 +129,7 @@ public function search(): array
                 'count' => $resultHandler->countSearchResults(),
                 'query' => $resultHandler->getQuery(),
             ]),
-            'pages' => \ceil($resultHandler->countSearchResults() / SEARCH_RESULTS_PER_PAGE),
+            'pages' => (int)\ceil($resultHandler->countSearchResults() / SEARCH_RESULTS_PER_PAGE),
             'pageNo' => $this->parameters['pageNo'] ?: 1,
             'searchID' => $search->searchID,
             'template' => WCF::getTPL()->render($templateName['application'], $templateName['templateName'], [
@@ -152,6 +158,7 @@ public function validateGetSearchResults(): void
     }
 
     /**
+     * @return array{template: string}
      * @since 5.5
      */
     public function getSearchResults(): array
diff --git a/wcfsetup/install/files/lib/data/search/SearchEditor.class.php b/wcfsetup/install/files/lib/data/search/SearchEditor.class.php
index b84d3318ee7..ba7c5f739f3 100644
--- a/wcfsetup/install/files/lib/data/search/SearchEditor.class.php
+++ b/wcfsetup/install/files/lib/data/search/SearchEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Search      create(array $parameters = [])
- * @method      Search      getDecoratedObject()
- * @mixin       Search
+ * @mixin Search
+ * @extends DatabaseObjectEditor<Search>
  */
 class SearchEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/search/SearchList.class.php b/wcfsetup/install/files/lib/data/search/SearchList.class.php
index b5d85ce39d4..d4b007a522b 100644
--- a/wcfsetup/install/files/lib/data/search/SearchList.class.php
+++ b/wcfsetup/install/files/lib/data/search/SearchList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Search      current()
- * @method  Search[]    getObjects()
- * @method  Search|null getSingleObject()
- * @method  Search|null search($objectID)
- * @property    Search[] $objects
+ * @extends DatabaseObjectList<Search>
  */
 class SearchList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordAction.class.php b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordAction.class.php
index 460b7d9b56d..4b57236f281 100644
--- a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordAction.class.php
+++ b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  SearchKeyword       create()
- * @method  SearchKeywordEditor[]   getObjects()
- * @method  SearchKeywordEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<SearchKeyword, SearchKeywordEditor>
  */
 class SearchKeywordAction extends AbstractDatabaseObjectAction implements ISearchAction
 {
@@ -68,6 +66,8 @@ public function getSearchResultList()
 
     /**
      * Inserts a new keyword if it does not already exist, or updates it if it does.
+     *
+     * @return void
      * @since 5.2
      */
     public function registerSearch()
diff --git a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordEditor.class.php b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordEditor.class.php
index 7fd686937f5..759b00552c4 100644
--- a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordEditor.class.php
+++ b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static SearchKeyword   create(array $parameters = [])
- * @method      SearchKeyword   getDecoratedObject()
- * @mixin       SearchKeyword
+ * @mixin SearchKeyword
+ * @extends DatabaseObjectEditor<SearchKeyword>
  */
 class SearchKeywordEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordList.class.php b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordList.class.php
index 1be4a7ef7f3..3920eecdec8 100644
--- a/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordList.class.php
+++ b/wcfsetup/install/files/lib/data/search/keyword/SearchKeywordList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  SearchKeyword       current()
- * @method  SearchKeyword[]     getObjects()
- * @method  SearchKeyword|null  getSingleObject()
- * @method  SearchKeyword|null  search($objectID)
- * @property    SearchKeyword[] $objects
+ * @extends DatabaseObjectList<SearchKeyword>
  */
 class SearchKeywordList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerAction.class.php b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerAction.class.php
index fed856da656..11d246d3fc3 100644
--- a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerAction.class.php
+++ b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerAction.class.php
@@ -10,9 +10,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method  ServiceWorker         create()
- * @method  ServiceWorkerEditor[]     getObjects()
- * @method  ServiceWorkerEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<ServiceWorker, ServiceWorkerEditor>
  */
 class ServiceWorkerAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerEditor.class.php b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerEditor.class.php
index 5caa8cd16fd..22571256bed 100644
--- a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerEditor.class.php
+++ b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerEditor.class.php
@@ -10,9 +10,8 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method  ServiceWorker     getDecoratedObject()
- * @method static ServiceWorker     create(array $parameters = [])
  * @mixin   ServiceWorker
+ * @extends DatabaseObjectEditor<ServiceWorker>
  */
 class ServiceWorkerEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerList.class.php b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerList.class.php
index 8becac07332..23d4d0f5022 100644
--- a/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerList.class.php
+++ b/wcfsetup/install/files/lib/data/service/worker/ServiceWorkerList.class.php
@@ -10,11 +10,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method  ServiceWorker     current()
- * @method  ServiceWorker[]   getObjects()
- * @method  ServiceWorker|null    getSingleObject()
- * @method  ServiceWorker|null    search($objectID)
- * @property    ServiceWorker[] $objects
+ * @extends DatabaseObjectList<ServiceWorker>
  */
 class ServiceWorkerList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/session/SessionAction.class.php b/wcfsetup/install/files/lib/data/session/SessionAction.class.php
index d85165f332a..f634880e28d 100644
--- a/wcfsetup/install/files/lib/data/session/SessionAction.class.php
+++ b/wcfsetup/install/files/lib/data/session/SessionAction.class.php
@@ -15,9 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Session         create()
- * @method  SessionEditor[]     getObjects()
- * @method  SessionEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Session, SessionEditor>
+ * @phpstan-ignore generics.notSubtype
  */
 class SessionAction extends AbstractDatabaseObjectAction
 {
@@ -39,6 +38,8 @@ class SessionAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates the 'keepAlive' action.
+     *
+     * @return void
      */
     public function validateKeepAlive()
     {
@@ -49,7 +50,7 @@ public function validateKeepAlive()
      * Updates session's last activity time to prevent it from expiring. In addition this method
      * will return updated counters for notifications and 3rd party components.
      *
-     * @return  mixed[]
+     * @return mixed[]
      */
     public function keepAlive()
     {
@@ -66,6 +67,8 @@ public function keepAlive()
 
     /**
      * Validates parameters to poll notification data.
+     *
+     * @return void
      */
     public function validatePoll()
     {
diff --git a/wcfsetup/install/files/lib/data/session/SessionEditor.class.php b/wcfsetup/install/files/lib/data/session/SessionEditor.class.php
index fd5217c27b0..40bf3923c43 100644
--- a/wcfsetup/install/files/lib/data/session/SessionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/session/SessionEditor.class.php
@@ -11,9 +11,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Session     getDecoratedObject()
- * @method static  Session     create(array $parameters = [])
- * @mixin   Session
+ * @method Session getDecoratedObject()
+ * @method static Session create(mixed[] $parameters = [])
+ * @mixin Session
  */
 class SessionEditor extends ACPSessionEditor
 {
diff --git a/wcfsetup/install/files/lib/data/session/SessionList.class.php b/wcfsetup/install/files/lib/data/session/SessionList.class.php
index 06be946b7de..8653927ccd5 100644
--- a/wcfsetup/install/files/lib/data/session/SessionList.class.php
+++ b/wcfsetup/install/files/lib/data/session/SessionList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\session;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -11,11 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Session     current()
- * @method  Session[]   getObjects()
- * @method  Session|null    getSingleObject()
- * @method  Session|null    search($objectID)
- * @property    Session[] $objects
+ * @template-covariant TDatabaseObject of Session|DatabaseObjectDecorator = Session
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class SessionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/smiley/Smiley.class.php b/wcfsetup/install/files/lib/data/smiley/Smiley.class.php
index ee129f663af..f2eebb2342f 100644
--- a/wcfsetup/install/files/lib/data/smiley/Smiley.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/Smiley.class.php
@@ -26,10 +26,19 @@
  */
 class Smiley extends DatabaseObject implements ITitledObject
 {
+    /**
+     * @var ?int
+     */
     protected $height;
 
+    /**
+     * @var ?int
+     */
     protected $width;
 
+    /**
+     * @var string[]
+     */
     public $smileyCodes;
 
     /**
diff --git a/wcfsetup/install/files/lib/data/smiley/SmileyAction.class.php b/wcfsetup/install/files/lib/data/smiley/SmileyAction.class.php
index b071a80e3c4..bc8cadeec11 100644
--- a/wcfsetup/install/files/lib/data/smiley/SmileyAction.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/SmileyAction.class.php
@@ -15,9 +15,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  SmileyEditor[]  getObjects()
- * @method  SmileyEditor    getSingleObject()
- * @property-read SmileyEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Smiley, SmileyEditor>
  */
 class SmileyAction extends AbstractDatabaseObjectAction implements ISortableAction
 {
diff --git a/wcfsetup/install/files/lib/data/smiley/SmileyCache.class.php b/wcfsetup/install/files/lib/data/smiley/SmileyCache.class.php
index aa9f70849d0..f17a33d3737 100644
--- a/wcfsetup/install/files/lib/data/smiley/SmileyCache.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/SmileyCache.class.php
@@ -20,19 +20,19 @@ class SmileyCache extends SingletonFactory
 {
     /**
      * cached smilies
-     * @var Smiley[][]
+     * @var array<int, array<int, Smiley>>
      */
     protected $cachedSmilies = [];
 
     /**
      * cached smilies with smiley code as key
-     * @var Smiley[]
+     * @var array<string, Smiley>
      */
     protected $cachedSmileyByCode = [];
 
     /**
      * cached smiley categories
-     * @var SmileyCategory[]
+     * @var array<?int, SmileyCategory>
      */
     protected $cachedCategories = [];
 
@@ -43,7 +43,7 @@ class SmileyCache extends SingletonFactory
     protected $visibleCategories;
 
     /**
-     * @var Smiley[]
+     * @var array<string, Smiley>
      */
     protected array $emojis;
 
@@ -57,6 +57,7 @@ protected function init()
         $this->cachedSmileyByCode = SmileyCacheBuilder::getInstance()->getData([], 'codes');
         $smileyCategories = CategoryHandler::getInstance()->getCategories('com.woltlab.wcf.bbcode.smiley');
 
+        // @phpstan-ignore assign.propertyType
         $this->cachedCategories[null] = new SmileyCategory(new Category(null, [
             'categoryID' => null,
             'parentCategoryID' => 0,
@@ -74,7 +75,7 @@ protected function init()
     /**
      * Returns all smilies.
      *
-     * @return  Smiley[][]
+     * @return array<int, array<int, Smiley>>
      */
     public function getSmilies()
     {
@@ -85,7 +86,7 @@ public function getSmilies()
      * Returns the smiley with the given smiley code or `null` if no such smiley exists.
      *
      * @param string $code
-     * @return  Smiley|null
+     * @return ?Smiley
      */
     public function getSmileyByCode($code)
     {
@@ -95,7 +96,7 @@ public function getSmileyByCode($code)
     /**
      * Returns all smiley categories.
      *
-     * @return  SmileyCategory[]
+     * @return array<?int, SmileyCategory>
      */
     public function getCategories()
     {
@@ -105,7 +106,7 @@ public function getCategories()
     /**
      * Returns all enabled smiley categories with at least one smiley.
      *
-     * @return  SmileyCategory[]
+     * @return array<int, SmileyCategory>
      */
     public function getVisibleCategories()
     {
@@ -129,8 +130,8 @@ public function getVisibleCategories()
     /**
      * Returns all the smilies of a category.
      *
-     * @param int $categoryID
-     * @return  array
+     * @param ?int $categoryID
+     * @return array<int, Smiley>
      */
     public function getCategorySmilies($categoryID = null)
     {
@@ -144,7 +145,8 @@ public function getCategorySmilies($categoryID = null)
     /**
      * Assigns the smilies and their categories to the template.
      *
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function assignVariables()
     {
@@ -168,7 +170,7 @@ public function assignVariables()
     /**
      * Return all smileys that match `:[a-z][a-z0-9]*+(?:_[a-z0-9]+)*:`.
      *
-     * @return Smiley[]
+     * @return array<string, Smiley>
      * @since 6.1
      */
     public function getEmojis(): array
diff --git a/wcfsetup/install/files/lib/data/smiley/SmileyEditor.class.php b/wcfsetup/install/files/lib/data/smiley/SmileyEditor.class.php
index 3288cbf90ee..5d968630aff 100644
--- a/wcfsetup/install/files/lib/data/smiley/SmileyEditor.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/SmileyEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Smiley      create(array $parameters = [])
- * @method      Smiley      getDecoratedObject()
  * @mixin       Smiley
+ * @extends DatabaseObjectEditor<Smiley>
+ * @implements IEditableCachedObject<Smiley>
  */
 class SmileyEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/smiley/SmileyList.class.php b/wcfsetup/install/files/lib/data/smiley/SmileyList.class.php
index f87aedf5a01..f3e080efb79 100644
--- a/wcfsetup/install/files/lib/data/smiley/SmileyList.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/SmileyList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Smiley      current()
- * @method  Smiley[]    getObjects()
- * @method  Smiley|null getSingleObject()
- * @method  Smiley|null search($objectID)
- * @property    Smiley[] $objects
+ * @extends DatabaseObjectList<Smiley>
  */
 class SmileyList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/smiley/category/SmileyCategory.class.php b/wcfsetup/install/files/lib/data/smiley/category/SmileyCategory.class.php
index 0f632ae6b9f..c36d1957f74 100644
--- a/wcfsetup/install/files/lib/data/smiley/category/SmileyCategory.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/category/SmileyCategory.class.php
@@ -16,11 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method      SmileyCategory[]    getChildCategories()
- * @method      SmileyCategory[]    getAllChildCategories()
- * @method      SmileyCategory      getParentCategory()
- * @method      SmileyCategory[]    getParentCategories()
- * @method static SmileyCategory|null getCategory($categoryID)
+ * @phpstan-ignore missingType.generics
  */
 class SmileyCategory extends AbstractDecoratedCategory implements \Countable, ITraversableObject
 {
@@ -44,6 +40,8 @@ class SmileyCategory extends AbstractDecoratedCategory implements \Countable, IT
 
     /**
      * Loads associated smilies from cache.
+     *
+     * @return void
      */
     public function loadSmilies()
     {
diff --git a/wcfsetup/install/files/lib/data/smiley/category/SmileyCategoryAction.class.php b/wcfsetup/install/files/lib/data/smiley/category/SmileyCategoryAction.class.php
index d928388a093..56fca2a2a1c 100644
--- a/wcfsetup/install/files/lib/data/smiley/category/SmileyCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/smiley/category/SmileyCategoryAction.class.php
@@ -15,9 +15,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Category        create()
- * @method  CategoryEditor[]    getObjects()
- * @method  CategoryEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Category, CategoryEditor>
  */
 class SmileyCategoryAction extends AbstractDatabaseObjectAction
 {
@@ -33,13 +31,14 @@ class SmileyCategoryAction extends AbstractDatabaseObjectAction
 
     /**
      * active smiley category
-     * @var SmileyCategory
+     * @var ?SmileyCategory
      */
     public $smileyCategory;
 
     /**
      * Validates smiley category id.
      *
+     * @return void
      * @deprecated 6.2 No longer in use.
      */
     public function validateGetSmilies()
@@ -54,7 +53,7 @@ public function validateGetSmilies()
     /**
      * Returns parsed template for smiley category's smilies.
      *
-     * @return  array
+     * @return array{smileyCategoryID: int, template: string}
      * @deprecated 6.2 No longer in use.
      */
     public function getSmilies()
diff --git a/wcfsetup/install/files/lib/data/stat/daily/StatDailyAction.class.php b/wcfsetup/install/files/lib/data/stat/daily/StatDailyAction.class.php
index c93a91d055e..e045e6be73f 100644
--- a/wcfsetup/install/files/lib/data/stat/daily/StatDailyAction.class.php
+++ b/wcfsetup/install/files/lib/data/stat/daily/StatDailyAction.class.php
@@ -6,6 +6,7 @@
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\exception\UserInputException;
+use wcf\system\stat\IStatDailyHandler;
 use wcf\system\WCF;
 
 /**
@@ -15,9 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StatDaily       create()
- * @method  StatDailyEditor[]   getObjects()
- * @method  StatDailyEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<StatDaily, StatDailyEditor>
  */
 class StatDailyAction extends AbstractDatabaseObjectAction
 {
@@ -28,6 +27,8 @@ class StatDailyAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates the getData action.
+     *
+     * @return void
      */
     public function validateGetData()
     {
@@ -72,6 +73,11 @@ public function validateGetData()
 
     /**
      * Returns the stat data.
+     *
+     * @return array<int, array{
+     *  label: string,
+     *  data: list<array{0: int, 1: mixed}>
+     * }>
      */
     public function getData()
     {
@@ -129,9 +135,15 @@ public function getData()
                 ];
             }
 
+            $processor = $objectType->getProcessor();
+            \assert($processor instanceof IStatDailyHandler);
+
+            $timestamp = \strtotime($row['date'] . ' UTC');
+            \assert($timestamp !== false);
+
             $data[$row['objectTypeID']]['data'][] = [
-                \strtotime($row['date'] . ' UTC'),
-                $objectType->getProcessor()->getFormattedCounter($value),
+                $timestamp,
+                $processor->getFormattedCounter($value),
             ];
         }
 
diff --git a/wcfsetup/install/files/lib/data/stat/daily/StatDailyEditor.class.php b/wcfsetup/install/files/lib/data/stat/daily/StatDailyEditor.class.php
index 9a35a353baf..4ceb52283bc 100644
--- a/wcfsetup/install/files/lib/data/stat/daily/StatDailyEditor.class.php
+++ b/wcfsetup/install/files/lib/data/stat/daily/StatDailyEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static StatDaily   create(array $parameters = [])
- * @method      StatDaily   getDecoratedObject()
  * @mixin       StatDaily
+ * @extends DatabaseObjectEditor<StatDaily>
  */
 class StatDailyEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/stat/daily/StatDailyList.class.php b/wcfsetup/install/files/lib/data/stat/daily/StatDailyList.class.php
index a9acf3d13f6..28f7e912af0 100644
--- a/wcfsetup/install/files/lib/data/stat/daily/StatDailyList.class.php
+++ b/wcfsetup/install/files/lib/data/stat/daily/StatDailyList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StatDaily       current()
- * @method  StatDaily[]     getObjects()
- * @method  StatDaily|null      getSingleObject()
- * @method  StatDaily|null      search($objectID)
- * @property    StatDaily[] $objects
+ * @extends DatabaseObjectList<StatDaily>
  */
 class StatDailyList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/style/ActiveStyle.class.php b/wcfsetup/install/files/lib/data/style/ActiveStyle.class.php
index 49b8721761c..c4bb217593d 100644
--- a/wcfsetup/install/files/lib/data/style/ActiveStyle.class.php
+++ b/wcfsetup/install/files/lib/data/style/ActiveStyle.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Style   getDecoratedObject()
  * @mixin   Style
+ * @extends DatabaseObjectDecorator<Style>
  */
 class ActiveStyle extends DatabaseObjectDecorator
 {
@@ -27,7 +27,7 @@ class ActiveStyle extends DatabaseObjectDecorator
      * Returns full path to specified image.
      *
      * @param string $image
-     * @return  string
+     * @return string
      */
     public function getImage($image)
     {
@@ -50,7 +50,7 @@ public function getImage($image)
     /**
      * Returns page logo.
      *
-     * @return  string
+     * @return string
      */
     public function getPageLogo()
     {
@@ -64,7 +64,7 @@ public function getPageLogo()
     /**
      * Returns mobile page logo.
      *
-     * @return  string
+     * @return string
      */
     public function getPageLogoMobile()
     {
diff --git a/wcfsetup/install/files/lib/data/style/Style.class.php b/wcfsetup/install/files/lib/data/style/Style.class.php
index e9d2da890cb..ee886f9984e 100644
--- a/wcfsetup/install/files/lib/data/style/Style.class.php
+++ b/wcfsetup/install/files/lib/data/style/Style.class.php
@@ -41,21 +41,25 @@
 class Style extends DatabaseObject implements ITitledObject
 {
     /**
+     * @var int
      * @since 5.4
      */
     protected $coverPhotoHeight = 0;
 
     /**
+     * @var int
      * @since 5.4
      */
     protected $coverPhotoWidth = 0;
 
     /**
+     * @var int
      * @since 5.4
      */
     protected $pageLogoSmallHeight = 0;
 
     /**
+     * @var int
      * @since 5.4
      */
     protected $pageLogoSmallWidth = 0;
@@ -182,6 +186,8 @@ public function getEmailFontFamily(): string
 
     /**
      * Loads style-specific variables.
+     *
+     * @return void
      */
     public function loadVariables()
     {
@@ -324,6 +330,7 @@ public function getFavicon(): string
     }
 
     /**
+     * @return string
      * @deprecated 6.0 Use Style::getFavicon() instead.
      */
     public function getRelativeFavicon()
@@ -413,6 +420,8 @@ public function getPageLogoSmallWidth(): int
      * Serve the WebP variant of the cover photo if the browser supports
      * it and the original cover photo is not a GIF.
      *
+     * @param bool $forceWebP
+     * @return bool
      * @since 5.4
      */
     protected function useWebP($forceWebP = null): bool
@@ -450,8 +459,8 @@ protected function getFaviconPath($filename, $absolutePath = true)
      * Splits the less variables string.
      *
      * @param string $variables
-     * @return  array
-     * @since   3.0
+     * @return array{preset: string, custom: string}
+     * @since 3.0
      */
     public static function splitLessVariables($variables)
     {
diff --git a/wcfsetup/install/files/lib/data/style/StyleAction.class.php b/wcfsetup/install/files/lib/data/style/StyleAction.class.php
index 9604c70c60d..8575be3fe7b 100644
--- a/wcfsetup/install/files/lib/data/style/StyleAction.class.php
+++ b/wcfsetup/install/files/lib/data/style/StyleAction.class.php
@@ -24,9 +24,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StyleEditor[]   getObjects()
- * @method  StyleEditor getSingleObject()
- * @property-read StyleEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Style, StyleEditor>
  */
 class StyleAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
@@ -59,23 +57,21 @@ class StyleAction extends AbstractDatabaseObjectAction implements IToggleAction
 
     /**
      * style object
-     * @var Style
+     * @var ?Style
      */
     public $style;
 
     /**
      * style editor object
-     * @var StyleEditor
+     * @var ?StyleEditor
      */
     public $styleEditor;
 
     /**
      * @inheritDoc
-     * @return  Style
      */
     public function create()
     {
-        /** @var Style $style */
         $style = parent::create();
 
         // add variables
@@ -125,6 +121,8 @@ public function update()
     }
 
     /**
+     * @param string $pathComponent
+     * @return void
      * @deprecated 5.4 This method is unused.
      */
     protected function removeDirectory($pathComponent)
@@ -263,7 +261,7 @@ private function setStyleVariables(Style $style, bool $isDarkMode): void
     /**
      * Updates style preview image.
      *
-     * @param Style $style
+     * @return void
      */
     protected function updateStylePreviewImage(Style $style)
     {
@@ -309,8 +307,8 @@ protected function updateStylePreviewImage(Style $style)
     /**
      * Updates style favicon files.
      *
-     * @param Style $style
-     * @since       3.1
+     * @return void
+     * @since 3.1
      */
     protected function updateFavicons(Style $style)
     {
@@ -414,8 +412,8 @@ protected function updateFavicons(Style $style)
     /**
      * Updates the style cover photo.
      *
-     * @param Style $style
-     * @since       3.1
+     * @return void
+     * @since 3.1
      */
     protected function updateCoverPhoto(Style $style)
     {
@@ -461,7 +459,8 @@ protected function updateCoverPhoto(Style $style)
     }
 
     /**
-     * @since       5.3
+     * @return void
+     * @since 5.3
      */
     protected function updateCustomAssets(Style $style)
     {
@@ -489,6 +488,7 @@ protected function updateCustomAssets(Style $style)
     /**
      * Validates parameters to copy a style.
      *
+     * @return void
      * @deprecated 6.2
      */
     public function validateCopy()
@@ -503,7 +503,7 @@ public function validateCopy()
     /**
      * Copies a style.
      *
-     * @return  string[]
+     * @return array{redirectURL: string}
      * @deprecated 6.2 Use `wcf\system\style\command\CopyStyle` instead.
      */
     public function copy()
@@ -518,10 +518,12 @@ public function copy()
 
     /**
      * Validates parameters to change user style.
+     *
+     * @return void
      */
     public function validateChangeStyle()
     {
-        $this->style = $this->getSingleObject();
+        $this->style = $this->getSingleObject()->getDecoratedObject();
         if ($this->style->isDisabled && !WCF::getSession()->getPermission('admin.style.canUseDisabledStyle')) {
             throw new PermissionDeniedException();
         }
@@ -529,6 +531,8 @@ public function validateChangeStyle()
 
     /**
      * Changes user style.
+     *
+     * @return void
      */
     public function changeStyle()
     {
@@ -554,6 +558,8 @@ public function changeStyle()
 
     /**
      * Validates the 'getStyleChooser' action.
+     *
+     * @return void
      */
     public function validateGetStyleChooser()
     {
@@ -563,7 +569,7 @@ public function validateGetStyleChooser()
     /**
      * Returns the style chooser dialog.
      *
-     * @return  string[]
+     * @return array{actionName: string, template: string}
      */
     public function getStyleChooser()
     {
@@ -585,7 +591,8 @@ public function getStyleChooser()
     /**
      * Validates the mark as tainted action.
      *
-     * @since   3.0
+     * @return void
+     * @since 3.0
      */
     public function validateMarkAsTainted()
     {
diff --git a/wcfsetup/install/files/lib/data/style/StyleEditor.class.php b/wcfsetup/install/files/lib/data/style/StyleEditor.class.php
index 7388a04c5ba..d8f64dbe8d7 100644
--- a/wcfsetup/install/files/lib/data/style/StyleEditor.class.php
+++ b/wcfsetup/install/files/lib/data/style/StyleEditor.class.php
@@ -39,8 +39,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Style   getDecoratedObject()
  * @mixin   Style
+ * @extends DatabaseObjectEditor<Style>
+ * @implements IEditableCachedObject<Style>
  */
 final class StyleEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -145,7 +146,7 @@ public static function deleteAll(array $objectIDs = [])
      *
      * @since 5.4
      */
-    private function removeDirectory(string $pathComponent)
+    private function removeDirectory(string $pathComponent): void
     {
         $dir = WCF_DIR . $pathComponent;
         if (\is_dir($dir)) {
@@ -167,6 +168,8 @@ private function removeDirectory(string $pathComponent)
 
     /**
      * Sets this style as default style.
+     *
+     * @return void
      */
     public function setAsDefault()
     {
@@ -188,6 +191,8 @@ public function setAsDefault()
 
     /**
      * Deletes the style's default cover photo.
+     *
+     * @return void
      */
     public function deleteCoverPhoto()
     {
@@ -245,8 +250,7 @@ public function createCoverPhotoVariant(?string $sourceLocation = null)
     /**
      * Reads the data of a style exchange format file.
      *
-     * @param Tar $tar
-     * @return  array
+     * @return mixed[]
      * @throws  SystemException
      */
     public static function readStyleData(Tar $tar)
@@ -397,7 +401,7 @@ public static function readStyleData(Tar $tar)
      *
      * @param string $filename
      * @param string $content
-     * @return  array
+     * @return array<string, string>
      */
     public static function readVariablesData($filename, $content)
     {
@@ -410,7 +414,7 @@ public static function readVariablesData($filename, $content)
 
         /** @var \DOMElement $variable */
         foreach ($variables as $variable) {
-            $data[$variable->getAttribute('name')] = $variable->nodeValue;
+            $data[$variable->getAttribute('name')] = $variable->textContent;
         }
 
         return $data;
@@ -420,7 +424,7 @@ public static function readVariablesData($filename, $content)
      * Returns the data of a style exchange format file.
      *
      * @param string $filename
-     * @return  array
+     * @return mixed[]
      */
     public static function getStyleData($filename)
     {
@@ -839,6 +843,7 @@ public static function import($filename, $packageID = 1, ?self $style = null, $s
      *
      * @param StyleEditor $styleEditor
      * @param string[] $descriptions
+     * @return void
      */
     protected static function saveLocalizedDescriptions(self $styleEditor, array $descriptions)
     {
@@ -912,6 +917,7 @@ protected static function getFileLocation($location)
      * @param bool $templates
      * @param bool $images
      * @param string $packageName
+     * @return void
      */
     public function export($templates = false, $images = false, $packageName = '')
     {
@@ -1274,6 +1280,8 @@ public function setVariables(array $variables, array $variablesDarkMode): void
 
     /**
      * Writes the style-*.css file.
+     *
+     * @return void
      */
     public function writeStyleFile()
     {
@@ -1282,7 +1290,6 @@ public function writeStyleFile()
 
     /**
      * @inheritDoc
-     * @return  Style
      */
     public static function create(array $parameters = [])
     {
diff --git a/wcfsetup/install/files/lib/data/style/StyleList.class.php b/wcfsetup/install/files/lib/data/style/StyleList.class.php
index 45475f52de5..539ee5586b5 100644
--- a/wcfsetup/install/files/lib/data/style/StyleList.class.php
+++ b/wcfsetup/install/files/lib/data/style/StyleList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Style       current()
- * @method  Style[]     getObjects()
- * @method  Style|null  getSingleObject()
- * @method  Style|null  search($objectID)
- * @property    Style[] $objects
+ * @extends DatabaseObjectList<Style>
  */
 class StyleList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/style/variable/StyleVariableAction.class.php b/wcfsetup/install/files/lib/data/style/variable/StyleVariableAction.class.php
index ec337ee6937..f2f6b6dc9c4 100644
--- a/wcfsetup/install/files/lib/data/style/variable/StyleVariableAction.class.php
+++ b/wcfsetup/install/files/lib/data/style/variable/StyleVariableAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StyleVariable       create()
- * @method  StyleVariableEditor[]   getObjects()
- * @method  StyleVariableEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<StyleVariable, StyleVariableEditor>
  */
 class StyleVariableAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/style/variable/StyleVariableEditor.class.php b/wcfsetup/install/files/lib/data/style/variable/StyleVariableEditor.class.php
index c4eb80adb6b..e0d9a5b7c75 100644
--- a/wcfsetup/install/files/lib/data/style/variable/StyleVariableEditor.class.php
+++ b/wcfsetup/install/files/lib/data/style/variable/StyleVariableEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static StyleVariable   create(array $parameters = [])
- * @method      StyleVariable   getDecoratedObject()
  * @mixin       StyleVariable
+ * @extends DatabaseObjectEditor<StyleVariable>
  */
 class StyleVariableEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/style/variable/StyleVariableList.class.php b/wcfsetup/install/files/lib/data/style/variable/StyleVariableList.class.php
index 280e22ff45b..891e94a6a7b 100644
--- a/wcfsetup/install/files/lib/data/style/variable/StyleVariableList.class.php
+++ b/wcfsetup/install/files/lib/data/style/variable/StyleVariableList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  StyleVariable       current()
- * @method  StyleVariable[]     getObjects()
- * @method  StyleVariable|null  getSingleObject()
- * @method  StyleVariable|null  search($objectID)
- * @property    StyleVariable[] $objects
+ * @extends DatabaseObjectList<StyleVariable>
  */
 class StyleVariableList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/tag/TagAction.class.php b/wcfsetup/install/files/lib/data/tag/TagAction.class.php
index f0b9e689538..d0b76458c60 100644
--- a/wcfsetup/install/files/lib/data/tag/TagAction.class.php
+++ b/wcfsetup/install/files/lib/data/tag/TagAction.class.php
@@ -15,9 +15,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TagEditor[] getObjects()
- * @method  TagEditor   getSingleObject()
- * @property TagEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Tag, TagEditor>
  */
 class TagAction extends AbstractDatabaseObjectAction implements ISearchAction
 {
@@ -63,7 +61,6 @@ public function validateGetSearchResultList()
     public function create()
     {
         $tag = parent::create();
-        \assert($tag instanceof Tag);
 
         $editor = new TagEditor($tag);
         $this->saveSynonyms($editor);
diff --git a/wcfsetup/install/files/lib/data/tag/TagCloudTag.class.php b/wcfsetup/install/files/lib/data/tag/TagCloudTag.class.php
index adc5d3e1b11..9c0bc3e379a 100644
--- a/wcfsetup/install/files/lib/data/tag/TagCloudTag.class.php
+++ b/wcfsetup/install/files/lib/data/tag/TagCloudTag.class.php
@@ -11,10 +11,10 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Tag getDecoratedObject()
  * @mixin   Tag
  *
  * @property-read   int|null $counter    number of the times the tag has been used for a certain object type or `null`
+ * @extends DatabaseObjectDecorator<Tag>
  */
 class TagCloudTag extends DatabaseObjectDecorator
 {
@@ -33,6 +33,7 @@ class TagCloudTag extends DatabaseObjectDecorator
      * Sets the weight of the tag.
      *
      * @param int $weight
+     * @return void
      */
     public function setWeight($weight)
     {
@@ -42,7 +43,7 @@ public function setWeight($weight)
     /**
      * Returns the weight of the tag.
      *
-     * @return  int
+     * @return int
      */
     public function getWeight()
     {
diff --git a/wcfsetup/install/files/lib/data/tag/TagEditor.class.php b/wcfsetup/install/files/lib/data/tag/TagEditor.class.php
index 617a9ff95bc..aaed5635260 100644
--- a/wcfsetup/install/files/lib/data/tag/TagEditor.class.php
+++ b/wcfsetup/install/files/lib/data/tag/TagEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static Tag create(array $parameters = [])
- * @method      Tag getDecoratedObject()
  * @mixin       Tag
+ * @extends DatabaseObjectEditor<Tag>
  */
 class TagEditor extends DatabaseObjectEditor
 {
@@ -26,7 +25,7 @@ class TagEditor extends DatabaseObjectEditor
     /**
      * Adds the given tag, and all of it's synonyms as a synonym.
      *
-     * @param Tag $synonym
+     * @return void
      */
     public function addSynonym(Tag $synonym)
     {
diff --git a/wcfsetup/install/files/lib/data/tag/TagList.class.php b/wcfsetup/install/files/lib/data/tag/TagList.class.php
index b90f81f0d0c..c9152b3393e 100644
--- a/wcfsetup/install/files/lib/data/tag/TagList.class.php
+++ b/wcfsetup/install/files/lib/data/tag/TagList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Tag     current()
- * @method  Tag[]       getObjects()
- * @method  Tag|null    getSingleObject()
- * @method  Tag|null    search($objectID)
- * @property    Tag[] $objects
+ * @extends DatabaseObjectList<Tag>
  */
 class TagList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/template/TemplateAction.class.php b/wcfsetup/install/files/lib/data/template/TemplateAction.class.php
index 1eef9a04a25..cb56c709560 100644
--- a/wcfsetup/install/files/lib/data/template/TemplateAction.class.php
+++ b/wcfsetup/install/files/lib/data/template/TemplateAction.class.php
@@ -12,8 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateEditor[]    getObjects()
- * @method  TemplateEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<Template, TemplateEditor>
  */
 class TemplateAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/template/TemplateEditor.class.php b/wcfsetup/install/files/lib/data/template/TemplateEditor.class.php
index 1611ce0b276..52a5a72f008 100644
--- a/wcfsetup/install/files/lib/data/template/TemplateEditor.class.php
+++ b/wcfsetup/install/files/lib/data/template/TemplateEditor.class.php
@@ -15,8 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Template    getDecoratedObject()
  * @mixin   Template
+ * @extends DatabaseObjectEditor<Template>
  */
 class TemplateEditor extends DatabaseObjectEditor
 {
@@ -27,7 +27,6 @@ class TemplateEditor extends DatabaseObjectEditor
 
     /**
      * @inheritDoc
-     * @return  Template
      */
     public static function create(array $parameters = [])
     {
@@ -36,13 +35,13 @@ public static function create(array $parameters = [])
             $parameters['packageID'] = PACKAGE_ID;
         }
 
-        $object = parent::create($parameters);
-        \assert($object instanceof Template);
-        return $object;
+        return parent::create($parameters);
     }
 
     /**
      * Saves the source of this template.
+     *
+     * @return void
      */
     public function setSource(string $source)
     {
@@ -63,6 +62,7 @@ public function setSource(string $source)
      *
      * @param string $name
      * @param int $templateGroupID
+     * @return void
      */
     public function rename($name, $templateGroupID = 0)
     {
@@ -94,6 +94,8 @@ public function rename($name, $templateGroupID = 0)
 
     /**
      * Deletes this template.
+     *
+     * @return void
      */
     public function delete()
     {
@@ -107,6 +109,8 @@ public function delete()
 
     /**
      * Deletes the file of this template.
+     *
+     * @return void
      */
     public function deleteFile()
     {
@@ -135,6 +139,8 @@ public static function deleteAll(array $objectIDs = [])
 
     /**
      * Deletes the compiled files of this template.
+     *
+     * @return void
      */
     public function deleteCompiledFiles()
     {
diff --git a/wcfsetup/install/files/lib/data/template/TemplateList.class.php b/wcfsetup/install/files/lib/data/template/TemplateList.class.php
index 14d3356c77b..f6dcd32627e 100644
--- a/wcfsetup/install/files/lib/data/template/TemplateList.class.php
+++ b/wcfsetup/install/files/lib/data/template/TemplateList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Template        current()
- * @method  Template[]      getObjects()
- * @method  Template|null       getSingleObject()
- * @method  Template|null       search($objectID)
- * @property    Template[] $objects
+ * @extends DatabaseObjectList<Template>
  */
 class TemplateList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/template/group/I18nTemplateGroupList.class.php b/wcfsetup/install/files/lib/data/template/group/I18nTemplateGroupList.class.php
index a7a9d4e41f7..90cc70ad967 100644
--- a/wcfsetup/install/files/lib/data/template/group/I18nTemplateGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/I18nTemplateGroupList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method  TemplateGroup       current()
- * @method  TemplateGroup[]     getObjects()
- * @method  TemplateGroup|null  getSingleObject()
- * @method  TemplateGroup|null  search($objectID)
- * @property    TemplateGroup[] $objects
+ * @extends I18nDatabaseObjectList<TemplateGroup>
  */
 class I18nTemplateGroupList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroup.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroup.class.php
index 19b63e31fe5..4d28aae2cba 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroup.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroup.class.php
@@ -31,13 +31,16 @@ class TemplateGroup extends DatabaseObject implements ITitledObject
      */
     protected static $templateGroupStructure;
 
+    /**
+     * @var array<int, string>
+     */
     protected static $selectList;
 
     /**
      * Returns whether the template group is immutable (i.e. whether it's the email
      * or shared template group).
      *
-     * @return  bool
+     * @return bool
      */
     public function isImmutable()
     {
@@ -47,7 +50,7 @@ public function isImmutable()
     /**
      * Returns the localized name of the template group.
      *
-     * @return  string
+     * @return string
      */
     public function getName()
     {
@@ -66,7 +69,7 @@ public function getTitle(): string
      * @param int[] $ignore Array of template group ids that should be excluded with all of their children.
      *                      -1 denotes that all immutable groups should be ignored.
      * @param int $initialDepth Specifies the initial indentation depth of the list
-     * @return  array
+     * @return array<int, string>
      */
     public static function getSelectList($ignore = [], $initialDepth = 0)
     {
@@ -78,7 +81,7 @@ public static function getSelectList($ignore = [], $initialDepth = 0)
         return self::$selectList;
     }
 
-    private static function buildTemplateGroupStructure()
+    private static function buildTemplateGroupStructure(): void
     {
         if (self::$templateGroupStructure === null) {
             self::$templateGroupStructure = [];
@@ -97,6 +100,7 @@ private static function buildTemplateGroupStructure()
     /**
      * Returns a list of all parent template groups.
      *
+     * @param int $parentID
      * @return \Generator<TemplateGroup>
      */
     public static function getParentTemplatesGroups($parentID = 0): \Generator
@@ -114,7 +118,8 @@ public static function getParentTemplatesGroups($parentID = 0): \Generator
      *
      * @param int $parentID id of the parent template group
      * @param int $depth current list depth
-     * @param array $ignore list of template group ids to ignore in result
+     * @param int[] $ignore list of template group ids to ignore in result
+     * @return void
      */
     protected static function makeSelectList($parentID = 0, $depth = 0, $ignore = [])
     {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroupAction.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroupAction.class.php
index b5e17958ef2..f706eab2a55 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroupAction.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroupAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateGroup       create()
- * @method  TemplateGroupEditor[]   getObjects()
- * @method  TemplateGroupEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<TemplateGroup, TemplateGroupEditor>
  */
 class TemplateGroupAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroupEditor.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroupEditor.class.php
index 76ea1d9e5ff..04d37ad01b0 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroupEditor.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroupEditor.class.php
@@ -17,9 +17,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static TemplateGroup   create(array $parameters = [])
- * @method      TemplateGroup   getDecoratedObject()
  * @mixin       TemplateGroup
+ * @extends DatabaseObjectEditor<TemplateGroup>
+ * @implements IEditableCachedObject<TemplateGroup>
  */
 class TemplateGroupEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -78,6 +78,8 @@ public static function deleteAll(array $objectIDs = [])
 
     /**
      * Deletes the folder of this template group.
+     *
+     * @return void
      */
     public function deleteFolder()
     {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroupList.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroupList.class.php
index 053c993c104..3ef160b9c07 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroupList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateGroup       current()
- * @method  TemplateGroup[]     getObjects()
- * @method  TemplateGroup|null  getSingleObject()
- * @method  TemplateGroup|null  search($objectID)
- * @property    TemplateGroup[] $objects
+ * @extends DatabaseObjectList<TemplateGroup>
  */
 class TemplateGroupList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroupNode.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroupNode.class.php
index 0514f08846f..a47e71a8751 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroupNode.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroupNode.class.php
@@ -13,8 +13,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateGroup    getDecoratedObject()
  * @mixin   TemplateGroup
+ * @extends DatabaseObjectDecorator<TemplateGroup>
  */
 final class TemplateGroupNode extends DatabaseObjectDecorator implements IObjectTreeNode
 {
diff --git a/wcfsetup/install/files/lib/data/template/group/TemplateGroupNodeTree.class.php b/wcfsetup/install/files/lib/data/template/group/TemplateGroupNodeTree.class.php
index 7eb7e132341..755640ce740 100644
--- a/wcfsetup/install/files/lib/data/template/group/TemplateGroupNodeTree.class.php
+++ b/wcfsetup/install/files/lib/data/template/group/TemplateGroupNodeTree.class.php
@@ -8,6 +8,8 @@
  * @author  Olaf Braun
  * @copyright   2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements \IteratorAggregate<int, TemplateGroupNode>
  */
 final class TemplateGroupNodeTree implements \IteratorAggregate
 {
@@ -15,30 +17,26 @@ final class TemplateGroupNodeTree implements \IteratorAggregate
      * list of ids of template group which will not be included in the node tree
      * @var int[]
      */
-    protected array $excludedTemplateGroupIDs = [];
+    private array $excludedTemplateGroupIDs = [];
 
     /**
      * maximum depth considered when building the node tree
-     * @var int
      */
-    protected int $maxDepth = -1;
+    private int $maxDepth = -1;
 
     /**
      * id of the template group
-     * @var int
      */
-    protected int $parentTemplateGroupID = 0;
+    private int $parentTemplateGroupID = 0;
 
     /**
      * parent template group node
-     * @var TemplateGroupNode
      */
-    protected TemplateGroupNode $parentNode;
+    private TemplateGroupNode $parentNode;
 
     /**
      * Creates a new instance of TemplateGroupNodeTree.
      *
-     * @param int $parentTemplateGroupID
      * @param int[] $excludedTemplateGroupIDs
      */
     public function __construct(
@@ -53,14 +51,15 @@ public function __construct(
      * Sets the maximum depth considered when building the node tree, defaults
      * to -1 which equals infinite.
      */
-    public function setMaxDepth(int $maxDepth)
+    public function setMaxDepth(int $maxDepth): void
     {
         $this->maxDepth = $maxDepth;
     }
 
     /**
-     * @inheritDoc
+     * @return \RecursiveIteratorIterator<TemplateGroupNode>
      */
+    #[\Override]
     public function getIterator(): \Traversable
     {
         if (!isset($this->parentNode)) {
@@ -73,7 +72,7 @@ public function getIterator(): \Traversable
     /**
      * Builds the template group node tree.
      */
-    protected function buildTree()
+    private function buildTree(): void
     {
         $this->parentNode = $this->getNode($this->parentTemplateGroupID);
         $this->buildTreeLevel($this->parentNode, $this->maxDepth);
@@ -81,11 +80,8 @@ protected function buildTree()
 
     /**
      * Returns the template group node for the template group with the given id.
-     *
-     * @param int $templateGroupID
-     * @return  TemplateGroupNode
      */
-    protected function getNode(int $templateGroupID): TemplateGroupNode
+    private function getNode(int $templateGroupID): TemplateGroupNode
     {
         if (!$templateGroupID) {
             $templateGroup = new TemplateGroup(null, [
@@ -101,7 +97,7 @@ protected function getNode(int $templateGroupID): TemplateGroupNode
     /**
      * Builds a certain level of the tree.
      */
-    protected function buildTreeLevel(TemplateGroupNode $parentNode, int $depth = 0)
+    private function buildTreeLevel(TemplateGroupNode $parentNode, int $depth = 0): void
     {
         if ($this->maxDepth != -1 && $depth < 0) {
             return;
@@ -123,7 +119,7 @@ protected function buildTreeLevel(TemplateGroupNode $parentNode, int $depth = 0)
      * Returns true if the given template group node fulfils all relevant conditions
      * to be included in this tree.
      */
-    protected function isIncluded(TemplateGroupNode $templateGroupNode): bool
+    private function isIncluded(TemplateGroupNode $templateGroupNode): bool
     {
         return !\in_array(
             $templateGroupNode->templateGroupID,
diff --git a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerAction.class.php b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerAction.class.php
index ffe65b484f9..1a5eb1ebb89 100644
--- a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerAction.class.php
+++ b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateListener        create()
- * @method  TemplateListenerEditor[]    getObjects()
- * @method  TemplateListenerEditor      getSingleObject()
+ * @extends AbstractDatabaseObjectAction<TemplateListener, TemplateListenerEditor>
  */
 class TemplateListenerAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerEditor.class.php b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerEditor.class.php
index aa6c0a10a0e..86d8eb1f8f1 100644
--- a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerEditor.class.php
+++ b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerEditor.class.php
@@ -14,9 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static TemplateListener    create(array $parameters = [])
- * @method      TemplateListener    getDecoratedObject()
  * @mixin       TemplateListener
+ * @extends DatabaseObjectEditor<TemplateListener>
+ * @implements IEditableCachedObject<TemplateListener>
  */
 class TemplateListenerEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerList.class.php b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerList.class.php
index 5af641bf7a2..459a39aac47 100644
--- a/wcfsetup/install/files/lib/data/template/listener/TemplateListenerList.class.php
+++ b/wcfsetup/install/files/lib/data/template/listener/TemplateListenerList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  TemplateListener        current()
- * @method  TemplateListener[]      getObjects()
- * @method  TemplateListener|null       getSingleObject()
- * @method  TemplateListener|null       search($objectID)
- * @property    TemplateListener[] $objects
+ * @extends DatabaseObjectList<TemplateListener>
  */
 class TemplateListenerList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/trophy/TrophyAction.class.php b/wcfsetup/install/files/lib/data/trophy/TrophyAction.class.php
index a993051ddcf..876ceb97c17 100644
--- a/wcfsetup/install/files/lib/data/trophy/TrophyAction.class.php
+++ b/wcfsetup/install/files/lib/data/trophy/TrophyAction.class.php
@@ -27,9 +27,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  TrophyEditor[]      getObjects()
- * @method  TrophyEditor        getSingleObject()
- * @property-read TrophyEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<Trophy, TrophyEditor>
  */
 class TrophyAction extends AbstractDatabaseObjectAction implements IToggleAction, IUploadAction, ISortableAction
 {
@@ -52,7 +50,6 @@ class TrophyAction extends AbstractDatabaseObjectAction implements IToggleAction
 
     /**
      * @inheritDoc
-     * @return  Trophy
      */
     public function create()
     {
@@ -62,7 +59,6 @@ public function create()
             unset($this->parameters['data']['showOrder']);
         }
 
-        /** @var Trophy $trophy */
         $trophy = parent::create();
 
         if (isset($this->parameters['tmpHash']) && $this->parameters['data']['type'] === Trophy::TYPE_IMAGE) {
@@ -284,7 +280,7 @@ public function upload()
     /**
      * Updates style preview image.
      *
-     * @param Trophy $trophy
+     * @return void
      */
     protected function updateTrophyImage(Trophy $trophy)
     {
diff --git a/wcfsetup/install/files/lib/data/trophy/TrophyCache.class.php b/wcfsetup/install/files/lib/data/trophy/TrophyCache.class.php
index aeb01449bb8..23f96d7b9a5 100644
--- a/wcfsetup/install/files/lib/data/trophy/TrophyCache.class.php
+++ b/wcfsetup/install/files/lib/data/trophy/TrophyCache.class.php
@@ -139,6 +139,8 @@ public function getEnabledTrophies()
 
     /**
      * Resets the cache for the trophies.
+     *
+     * @return void
      */
     public function clearCache()
     {
diff --git a/wcfsetup/install/files/lib/data/trophy/TrophyEditor.class.php b/wcfsetup/install/files/lib/data/trophy/TrophyEditor.class.php
index fa1c2d39e91..c31bde5f260 100644
--- a/wcfsetup/install/files/lib/data/trophy/TrophyEditor.class.php
+++ b/wcfsetup/install/files/lib/data/trophy/TrophyEditor.class.php
@@ -14,9 +14,9 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method static Trophy create(array $parameters = [])
- * @method Trophy getDecoratedObject()
  * @mixin   Trophy
+ * @extends DatabaseObjectEditor<Trophy>
+ * @implements IEditableCachedObject<Trophy>
  */
 class TrophyEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -29,6 +29,7 @@ class TrophyEditor extends DatabaseObjectEditor implements IEditableCachedObject
      * Sets the show order of the trophy.
      *
      * @param int $showOrder
+     * @return void
      */
     public function setShowOrder($showOrder = 0)
     {
diff --git a/wcfsetup/install/files/lib/data/trophy/TrophyList.class.php b/wcfsetup/install/files/lib/data/trophy/TrophyList.class.php
index 3cedd11d23c..ace4e1b13c3 100644
--- a/wcfsetup/install/files/lib/data/trophy/TrophyList.class.php
+++ b/wcfsetup/install/files/lib/data/trophy/TrophyList.class.php
@@ -12,12 +12,6 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  Trophy      current()
- * @method  Trophy[]    getObjects()
- * @method  Trophy|null getSingleObject()
- * @method  Trophy|null search($objectID)
- * @property    Trophy[] $objects
+ * @extends DatabaseObjectList<Trophy>
  */
-class TrophyList extends DatabaseObjectList
-{
-}
+class TrophyList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/trophy/category/TrophyCategory.class.php b/wcfsetup/install/files/lib/data/trophy/category/TrophyCategory.class.php
index 3cca2b588c4..124a6b04bcf 100644
--- a/wcfsetup/install/files/lib/data/trophy/category/TrophyCategory.class.php
+++ b/wcfsetup/install/files/lib/data/trophy/category/TrophyCategory.class.php
@@ -33,7 +33,7 @@ class TrophyCategory extends AbstractDecoratedCategory implements ITitledLinkObj
     const OBJECT_TYPE_NAME = 'com.woltlab.wcf.trophy.category';
 
     /**
-     * @inheritDoc
+     * @return bool
      */
     public function isAccessible(?User $user = null)
     {
diff --git a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlAction.class.php b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlAction.class.php
index 3d922c7e572..412b8b1b3fc 100644
--- a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlAction.class.php
+++ b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlAction.class.php
@@ -15,8 +15,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.4
  *
- * @method  UnfurlUrlEditor[]   getObjects()
- * @method  UnfurlUrlEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UnfurlUrl, UnfurlUrlEditor>
  */
 class UnfurlUrlAction extends AbstractDatabaseObjectAction
 {
@@ -53,6 +52,9 @@ public function update()
         parent::update();
     }
 
+    /**
+     * @param array<string, int|float|string> $imageData
+     */
     private function saveImageData(array $imageData): int
     {
         $keys = $values = '';
diff --git a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlEditor.class.php b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlEditor.class.php
index 249e4a788b1..0ab42bf96ca 100644
--- a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlEditor.class.php
+++ b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlEditor.class.php
@@ -21,8 +21,8 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.4
  *
- * @method  UnfurlUrl   getDecoratedObject()
  * @mixin   UnfurlUrl
+ * @extends DatabaseObjectEditor<UnfurlUrl>
  */
 class UnfurlUrlEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlList.class.php b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlList.class.php
index 2a888fc9f7f..bc7e595be4b 100644
--- a/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlList.class.php
+++ b/wcfsetup/install/files/lib/data/unfurl/url/UnfurlUrlList.class.php
@@ -13,11 +13,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.4
  *
- * @method      UnfurlUrl           current()
- * @method      UnfurlUrl[]         getObjects()
- * @method      UnfurlUrl|null      getSingleObject()
- * @method      UnfurlUrl|null      search($objectID)
- * @property    UnfurlUrl[]         $objects
+ * @extends DatabaseObjectList<UnfurlUrl>
  */
 class UnfurlUrlList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/TUserAvatarObjectList.class.php b/wcfsetup/install/files/lib/data/user/TUserAvatarObjectList.class.php
index 238c4a6eaab..645465f5dd0 100644
--- a/wcfsetup/install/files/lib/data/user/TUserAvatarObjectList.class.php
+++ b/wcfsetup/install/files/lib/data/user/TUserAvatarObjectList.class.php
@@ -2,7 +2,7 @@
 
 namespace wcf\data\user;
 
-use wcf\data\DatabaseObjectList;
+use wcf\data\user\UserProfileList;
 use wcf\system\cache\runtime\FileRuntimeCache;
 
 /**
@@ -13,7 +13,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
  * @property    UserProfile[] $objects
- * @mixin DatabaseObjectList
+ * @mixin UserProfileList
  *
  * @since 6.2
  */
diff --git a/wcfsetup/install/files/lib/data/user/User.class.php b/wcfsetup/install/files/lib/data/user/User.class.php
index 9157ee859a2..b2fb91e7eab 100644
--- a/wcfsetup/install/files/lib/data/user/User.class.php
+++ b/wcfsetup/install/files/lib/data/user/User.class.php
@@ -98,7 +98,7 @@ final class User extends DatabaseObject implements IPopoverObject, IRouteControl
 
     /**
      * date time zone object
-     * @var \DateTimeZone
+     * @var ?\DateTimeZone
      */
     protected $timezoneObj;
 
@@ -116,8 +116,6 @@ final class User extends DatabaseObject implements IPopoverObject, IRouteControl
 
     const REGISTER_ACTIVATION_USER_AND_ADMIN = self::REGISTER_ACTIVATION_USER | self::REGISTER_ACTIVATION_ADMIN;
 
-    /** @noinspection PhpMissingParentConstructorInspection */
-
     /**
      * @inheritDoc
      */
@@ -148,7 +146,7 @@ public function __construct($id, $row = null, ?DatabaseObject $object = null)
      * Returns true if the given password is the correct password for this user.
      *
      * @param string $password
-     * @return  bool        password correct
+     * @return bool password correct
      */
     public function checkPassword(
         #[\SensitiveParameter]
@@ -191,6 +189,8 @@ public function checkPassword(
     }
 
     /**
+     * @param string $passwordHash
+     * @return false
      * @deprecated 5.4 - This method always returns false, as user sessions are long-lived now.
      */
     public function checkCookiePassword($passwordHash)
@@ -202,7 +202,7 @@ public function checkCookiePassword($passwordHash)
      * Returns an array with all the groups in which the actual user is a member.
      *
      * @param bool $skipCache
-     * @return  int[]
+     * @return int[]
      */
     public function getGroupIDs($skipCache = false)
     {
@@ -245,7 +245,7 @@ public function getGroupIDs($skipCache = false)
     /**
      * Returns a list of language ids for this user.
      *
-     * @return  int[]
+     * @return int[]
      */
     public function getLanguageIDs()
     {
@@ -287,7 +287,7 @@ public function getLanguageIDs()
      *
      * @param string $name user option name
      * @param bool $filterDisabled suppress values for disabled options
-     * @return  mixed               user option value
+     * @return mixed user option value
      */
     public function getUserOption($name, $filterDisabled = false)
     {
@@ -303,6 +303,8 @@ public function getUserOption($name, $filterDisabled = false)
 
     /**
      * Fetches all user options from cache.
+     *
+     * @return void
      */
     protected static function getUserOptionCache()
     {
@@ -313,7 +315,7 @@ protected static function getUserOptionCache()
      * Returns the id of a user option.
      *
      * @param string $name
-     * @return  int|null
+     * @return ?int
      */
     public static function getUserOptionID($name)
     {
@@ -341,7 +343,7 @@ public function __get($name)
      * Returns the user with the given username.
      *
      * @param string $username
-     * @return  User
+     * @return User
      */
     public static function getUserByUsername($username)
     {
@@ -364,7 +366,7 @@ public static function getUserByUsername($username)
      * Returns the user with the given email.
      *
      * @param string $email
-     * @return  User
+     * @return User
      */
     public static function getUserByEmail($email)
     {
@@ -387,7 +389,7 @@ public static function getUserByEmail($email)
      * Returns the user with the given authData.
      *
      * @param string $authData
-     * @return  User
+     * @return User
      */
     public static function getUserByAuthData($authData)
     {
@@ -409,8 +411,8 @@ public static function getUserByAuthData($authData)
     /**
      * Returns 3rd party auth provider name.
      *
-     * @return  string
-     * @since       5.2
+     * @return string
+     * @since 5.2
      */
     public function getAuthProvider()
     {
@@ -441,8 +443,8 @@ public function isMarked()
     /**
      * Returns true if the email is confirmed.
      *
-     * @return  bool
-     * @since       5.3
+     * @return bool
+     * @since 5.3
      */
     public function isEmailConfirmed()
     {
@@ -452,7 +454,7 @@ public function isEmailConfirmed()
     /**
      * Returns the time zone of this user.
      *
-     * @return  \DateTimeZone
+     * @return \DateTimeZone
      */
     public function getTimeZone()
     {
@@ -481,8 +483,8 @@ public function getLocalDate(int $timestamp): \DateTimeImmutable
     /**
      * Returns a list of users.
      *
-     * @param array $userIDs
-     * @return  User[]
+     * @param int[] $userIDs
+     * @return User[]
      */
     public static function getUsers(array $userIDs)
     {
diff --git a/wcfsetup/install/files/lib/data/user/UserAction.class.php b/wcfsetup/install/files/lib/data/user/UserAction.class.php
index dffeb595116..00a13dcddec 100644
--- a/wcfsetup/install/files/lib/data/user/UserAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserAction.class.php
@@ -36,9 +36,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserEditor[]    getObjects()
- * @method  UserEditor  getSingleObject()
- * @property-read UserEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<User, UserEditor>
  */
 class UserAction extends AbstractDatabaseObjectAction implements IClipboardAction, ISearchAction
 {
@@ -74,6 +72,8 @@ class UserAction extends AbstractDatabaseObjectAction implements IClipboardActio
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateCreate()
     {
@@ -84,6 +84,7 @@ public function validateCreate()
      * Validates accessible groups.
      *
      * @param bool $ignoreOwnUser
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      */
@@ -161,6 +162,8 @@ public function delete()
 
     /**
      * Validates permissions and parameters.
+     *
+     * @return void
      */
     public function validateUpdate()
     {
@@ -195,6 +198,8 @@ public function validateUpdate()
 
     /**
      * Validates the ban action.
+     *
+     * @return void
      */
     public function validateBan()
     {
@@ -206,6 +211,8 @@ public function validateBan()
 
     /**
      * Validates the unban action.
+     *
+     * @return void
      */
     public function validateUnban()
     {
@@ -216,6 +223,8 @@ public function validateUnban()
 
     /**
      * Bans users.
+     *
+     * @return string
      */
     public function ban()
     {
@@ -255,6 +264,8 @@ public function ban()
 
     /**
      * Unbans users.
+     *
+     * @return void
      */
     public function unban()
     {
@@ -276,7 +287,6 @@ public function unban()
 
     /**
      * @inheritDoc
-     * @return  User
      */
     public function create()
     {
@@ -445,6 +455,8 @@ public function update()
 
     /**
      * Remove users from given groups.
+     *
+     * @return void
      */
     public function removeFromGroups()
     {
@@ -475,6 +487,8 @@ public function removeFromGroups()
 
     /**
      * Add users to given groups.
+     *
+     * @return void
      */
     public function addToGroups()
     {
@@ -637,6 +651,7 @@ public function unmarkAll()
      * Unmarks users.
      *
      * @param int[] $userIDs
+     * @return void
      */
     protected function unmarkItems(array $userIDs = [])
     {
@@ -654,6 +669,8 @@ protected function unmarkItems(array $userIDs = [])
 
     /**
      * Validates the enable action.
+     *
+     * @return void
      */
     public function validateEnable()
     {
@@ -664,6 +681,8 @@ public function validateEnable()
 
     /**
      * Validates the disable action.
+     *
+     * @return void
      */
     public function validateDisable()
     {
@@ -672,6 +691,8 @@ public function validateDisable()
 
     /**
      * Validates the confirm email action.
+     *
+     * @return void
      * @since       5.3
      */
     public function validateConfirmEmail()
@@ -681,6 +702,8 @@ public function validateConfirmEmail()
 
     /**
      * Validates the unconfirm email action.
+     *
+     * @return void
      * @since       5.3
      */
     public function validateUnconfirmEmail()
@@ -690,6 +713,8 @@ public function validateUnconfirmEmail()
 
     /**
      * Marks the email address as confirmed. It also enables the user, iff the register method is user activation only.
+     *
+     * @return void
      * @since       5.3
      */
     public function confirmEmail()
@@ -713,6 +738,8 @@ public function confirmEmail()
 
     /**
      * Marks the email address as unconfirmed.
+     *
+     * @return void
      * @since       5.3
      */
     public function unconfirmEmail()
@@ -734,6 +761,8 @@ public function unconfirmEmail()
 
     /**
      * Enables users.
+     *
+     * @return void
      */
     public function enable()
     {
@@ -793,6 +822,8 @@ public function enable()
 
     /**
      * Disables users.
+     *
+     * @return void
      */
     public function disable()
     {
@@ -842,6 +873,7 @@ protected function readObjects()
                 WHERE       user_table.userID IN (" . \str_repeat('?,', \count($this->objectIDs) - 1) . "?)";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute($this->objectIDs);
+        // @phpstan-ignore argument.templateType
         while ($object = $statement->fetchObject($baseClass)) {
             $this->objects[] = new $this->className($object);
         }
@@ -849,6 +881,8 @@ protected function readObjects()
 
     /**
      * Validates the 'disableSignature' action.
+     *
+     * @return void
      */
     public function validateDisableSignature()
     {
@@ -860,6 +894,8 @@ public function validateDisableSignature()
 
     /**
      * Disables the signature of the handled users.
+     *
+     * @return void
      */
     public function disableSignature()
     {
@@ -885,6 +921,8 @@ public function disableSignature()
 
     /**
      * Validates the 'enableSignature' action.
+     *
+     * @return void
      */
     public function validateEnableSignature()
     {
@@ -903,6 +941,8 @@ public function validateEnableSignature()
 
     /**
      * Enables the signature of the handled users.
+     *
+     * @return void
      */
     public function enableSignature()
     {
@@ -919,6 +959,8 @@ public function enableSignature()
 
     /**
      * Validates the 'disableAvatar' action.
+     *
+     * @return void
      */
     public function validateDisableAvatar()
     {
@@ -930,6 +972,8 @@ public function validateDisableAvatar()
 
     /**
      * Disables the avatar of the handled users.
+     *
+     * @return void
      */
     public function disableAvatar()
     {
@@ -956,6 +1000,7 @@ public function disableAvatar()
     /**
      * Validates the 'disableCoverPhoto' action.
      *
+     * @return void
      * @since   5.2
      */
     public function validateDisableCoverPhoto()
@@ -969,6 +1014,7 @@ public function validateDisableCoverPhoto()
     /**
      * Disables the cover photo of the handled users.
      *
+     * @return void
      * @since   5.2
      */
     public function disableCoverPhoto()
@@ -995,6 +1041,8 @@ public function disableCoverPhoto()
 
     /**
      * Validates the 'enableAvatar' action.
+     *
+     * @return void
      */
     public function validateEnableAvatar()
     {
@@ -1013,6 +1061,8 @@ public function validateEnableAvatar()
 
     /**
      * Enables the avatar of the handled users.
+     *
+     * @return void
      */
     public function enableAvatar()
     {
@@ -1030,6 +1080,7 @@ public function enableAvatar()
     /**
      * Validates the 'enableCoverPhoto' action.
      *
+     * @return void
      * @since   5.2
      */
     public function validateEnableCoverPhoto()
@@ -1050,6 +1101,7 @@ public function validateEnableCoverPhoto()
     /**
      * Enables the cover photo of the handled users.
      *
+     * @return void
      * @since   5.2
      */
     public function enableCoverPhoto()
@@ -1068,8 +1120,8 @@ public function enableCoverPhoto()
     /**
      * Returns the remove content dialog.
      *
-     * @return      String[]
-     * @since       5.2
+     * @return array{template: string}
+     * @since 5.2
      */
     public function prepareRemoveContent()
     {
@@ -1096,7 +1148,8 @@ static function ($contentProvider) {
     /**
      * Validates the prepareRemoveContent method.
      *
-     * @since       5.2
+     * @return void
+     * @since 5.2
      */
     public function validatePrepareRemoveContent()
     {
@@ -1133,11 +1186,13 @@ public function validatePrepareRemoveContent()
     }
 
     /**
+     * @return void
      * @since 5.3
      */
     public function validateSaveUserConsent() {}
 
     /**
+     * @return void
      * @since 5.3
      */
     public function saveUserConsent()
@@ -1151,6 +1206,7 @@ public function saveUserConsent()
     /**
      * Validates the 'resendActivationMail' action.
      *
+     * @return void
      * @throws  IllegalLinkException
      * @throws  PermissionDeniedException
      * @throws  UserInputException
@@ -1169,7 +1225,6 @@ public function validateResendActivationMail()
         }
 
         foreach ($this->objects as $object) {
-            /** @var UserEditor $object */
             if (!$object->canEmailConfirm()) {
                 throw new UserInputException('objectIDs');
             }
@@ -1178,6 +1233,8 @@ public function validateResendActivationMail()
 
     /**
      * Triggers a new activation email.
+     *
+     * @return void
      * @since   5.2
      */
     public function resendActivationMail()
@@ -1211,6 +1268,7 @@ public function resendActivationMail()
     }
 
     /**
+     * @return void
      * @since   5.2
      */
     public function validateDevtoolsSetLanguage()
@@ -1227,6 +1285,7 @@ public function validateDevtoolsSetLanguage()
     }
 
     /**
+     * @return void
      * @since   5.2
      */
     public function devtoolsSetLanguage()
diff --git a/wcfsetup/install/files/lib/data/user/UserContentAction.class.php b/wcfsetup/install/files/lib/data/user/UserContentAction.class.php
index b5e8755ae40..b6abdaacf93 100644
--- a/wcfsetup/install/files/lib/data/user/UserContentAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserContentAction.class.php
@@ -16,6 +16,8 @@ class UserContentAction extends UserAction
 {
     /**
      * Checks permissions to bulk revert.
+     *
+     * @return void
      */
     public function validateBulkRevert()
     {
@@ -24,6 +26,8 @@ public function validateBulkRevert()
 
     /**
      * Bulk reverts changes made to history saving objects.
+     *
+     * @return void
      */
     public function bulkRevert()
     {
diff --git a/wcfsetup/install/files/lib/data/user/UserEditor.class.php b/wcfsetup/install/files/lib/data/user/UserEditor.class.php
index a21dc933af0..53d8c5caf62 100644
--- a/wcfsetup/install/files/lib/data/user/UserEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserEditor.class.php
@@ -20,8 +20,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  User    getDecoratedObject()
  * @mixin   User
+ * @extends DatabaseObjectEditor<User>
+ * @implements IEditableCachedObject<User>
  */
 class UserEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -32,7 +33,7 @@ class UserEditor extends DatabaseObjectEditor implements IEditableCachedObject
 
     /**
      * list of user options default values
-     * @var array
+     * @var array<int, int|float|string>
      */
     protected static $userOptionDefaultValues;
 
@@ -61,7 +62,6 @@ private static function getPasswordHash(
 
     /**
      * @inheritDoc
-     * @return  User
      */
     public static function create(array $parameters = [])
     {
@@ -117,6 +117,8 @@ public function update(array $parameters = [])
 
     /**
      * Inserts default options.
+     *
+     * @return void
      */
     protected static function createUserOptions(int $userID)
     {
@@ -153,7 +155,7 @@ protected static function createUserOptions(int $userID)
     /**
      * Updates user options.
      *
-     * @param array $userOptions
+     * @param array<int, int|float|string> $userOptions
      */
     public function updateUserOptions(array $userOptions = []): void
     {
diff --git a/wcfsetup/install/files/lib/data/user/UserList.class.php b/wcfsetup/install/files/lib/data/user/UserList.class.php
index 5dc3df47a13..ec2c2285e23 100644
--- a/wcfsetup/install/files/lib/data/user/UserList.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserList.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\data\user;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -11,11 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  User        current()
- * @method  User[]      getObjects()
- * @method  User|null   getSingleObject()
- * @method  User|null   search($objectID)
- * @property    User[] $objects
+ * @template-covariant TDatabaseObject of User|DatabaseObjectDecorator<User> = User
+ * @extends DatabaseObjectList<TDatabaseObject>
  */
 class UserList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/UserProfile.class.php b/wcfsetup/install/files/lib/data/user/UserProfile.class.php
index 6cb55f4ca19..3913e010668 100644
--- a/wcfsetup/install/files/lib/data/user/UserProfile.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserProfile.class.php
@@ -39,11 +39,11 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  User    getDecoratedObject()
  * @mixin   User
  * @property-read   int $sessionLastActivityTime
  * @property-read   bool $birthdayShowYear
  * @property-read   string $birthday
+ * @extends DatabaseObjectDecorator<User>
  */
 class UserProfile extends DatabaseObjectDecorator implements ITitledLinkObject
 {
@@ -560,6 +560,7 @@ public function getSpecialTrophies()
      * Prepares the special trophies for the given user ids.
      *
      * @param int[] $userIDs
+     * @return void
      * @since       5.2
      */
     public static function prepareSpecialTrophies(array $userIDs)
@@ -624,7 +625,7 @@ public static function prepareSpecialTrophies(array $userIDs)
     /**
      * Returns the last activity time.
      *
-     * @return  int
+     * @return int
      */
     public function getLastActivityTime()
     {
@@ -635,7 +636,7 @@ public function getLastActivityTime()
      * Returns a new user profile object.
      *
      * @param int $userID
-     * @return  UserProfile
+     * @return ?UserProfile
      * @deprecated  3.0, use UserProfileRuntimeCache::getObject()
      */
     public static function getUserProfile($userID)
@@ -647,7 +648,7 @@ public static function getUserProfile($userID)
      * Returns a list of user profiles.
      *
      * @param int[] $userIDs
-     * @return  UserProfile[]
+     * @return (UserProfile|null)[]
      * @deprecated  3.0, use UserProfileRuntimeCache::getObjects()
      */
     public static function getUserProfiles(array $userIDs)
@@ -681,7 +682,7 @@ public static function getUserProfileByUsername($username)
      * Returns the user profiles of the users with the given names.
      *
      * @param string[] $usernames
-     * @return  array<string, UserProfile|null>
+     * @return array<string, UserProfile|null>
      */
     public static function getUserProfilesByUsername(array $usernames)
     {
@@ -784,7 +785,7 @@ public function isAccessible(string $name, ?int $userID = null): bool
     /**
      * Returns true if current user profile is protected.
      *
-     * @return  bool
+     * @return bool
      */
     public function isProtected()
     {
@@ -795,7 +796,7 @@ public function isProtected()
      * Returns the age of this user.
      *
      * @param int $year
-     * @return  int
+     * @return int
      */
     public function getAge($year = null)
     {
@@ -829,7 +830,7 @@ public function getAge($year = null)
      * Returns the formatted birthday of this user.
      *
      * @param int $year
-     * @return  string
+     * @return string
      */
     public function getBirthday($year = null)
     {
@@ -871,7 +872,7 @@ public function getBirthday($year = null)
     /**
      * Returns the age of user account in days.
      *
-     * @return  int
+     * @return int
      */
     public function getProfileAge()
     {
@@ -882,7 +883,7 @@ public function getProfileAge()
      * Returns the value of the permission with the given name.
      *
      * @param string $permission
-     * @return  mixed       permission value
+     * @return mixed permission value
      */
     public function getPermission($permission)
     {
@@ -902,7 +903,7 @@ public function getPermission($permission)
      * compatibility, while preventing ACLs from overruling a 'Never' setting.
      *
      * @param string $permission
-     * @return      bool
+     * @return bool
      */
     public function getNeverPermission($permission)
     {
@@ -914,7 +915,7 @@ public function getNeverPermission($permission)
     /**
      * Returns the user title of this user.
      *
-     * @return  string
+     * @return string
      */
     public function getUserTitle()
     {
@@ -943,6 +944,8 @@ public function getRank(): ?UserRank
 
     /**
      * Loads group data from cache.
+     *
+     * @return void
      */
     protected function loadGroupData()
     {
@@ -952,7 +955,7 @@ protected function loadGroupData()
     /**
      * Returns the old username of this user.
      *
-     * @return  string
+     * @return string
      */
     public function getOldUsername()
     {
@@ -968,7 +971,7 @@ public function getOldUsername()
     /**
      * Returns true if this user can edit his profile.
      *
-     * @return  bool
+     * @return bool
      */
     public function canEditOwnProfile()
     {
@@ -999,6 +1002,7 @@ public function getEncodedEmail(): string
     }
 
     /**
+     * @return bool
      * @deprecated 5.4 This method is unused internally and redundant with `User::getAuthProvider()`.
      */
     public function isConnectedWithFacebook()
@@ -1007,6 +1011,7 @@ public function isConnectedWithFacebook()
     }
 
     /**
+     * @return bool
      * @deprecated 5.4 This method is unused internally and redundant with `User::getAuthProvider()`.
      */
     public function isConnectedWithGithub()
@@ -1015,6 +1020,7 @@ public function isConnectedWithGithub()
     }
 
     /**
+     * @return bool
      * @deprecated 5.4 This method is unused internally and redundant with `User::getAuthProvider()`.
      */
     public function isConnectedWithGoogle()
@@ -1023,6 +1029,7 @@ public function isConnectedWithGoogle()
     }
 
     /**
+     * @return bool
      * @deprecated 5.4 This method is unused internally and redundant with `User::getAuthProvider()`.
      */
     public function isConnectedWithTwitter()
@@ -1033,7 +1040,7 @@ public function isConnectedWithTwitter()
     /**
      * Returns 3rd party auth provider name.
      *
-     * @return  string
+     * @return string
      */
     public function getAuthProvider()
     {
@@ -1043,7 +1050,7 @@ public function getAuthProvider()
     /**
      * Return true if the user's signature is visible.
      *
-     * @return  bool
+     * @return bool
      */
     public function showSignature()
     {
@@ -1069,7 +1076,7 @@ public function showSignature()
     /**
      * Returns the parsed signature.
      *
-     * @return  string
+     * @return string
      */
     public function getSignature()
     {
@@ -1080,7 +1087,7 @@ public function getSignature()
      * Returns the formatted value of the user option with the given name.
      *
      * @param string $name
-     * @return  mixed
+     * @return mixed
      */
     public function getFormattedUserOption($name)
     {
@@ -1103,7 +1110,7 @@ public function getFormattedUserOption($name)
      * Returns true, if the active user has access to the user option with the given name.
      *
      * @param string $name
-     * @return  bool
+     * @return bool
      */
     public function isVisibleOption($name)
     {
@@ -1115,7 +1122,7 @@ public function isVisibleOption($name)
     /**
      * Returns the formatted username.
      *
-     * @return  string
+     * @return string
      */
     public function getFormattedUsername()
     {
@@ -1134,7 +1141,7 @@ public function getFormattedUsername()
     /**
      * Returns a HTML anchor link pointing to the decorated user.
      *
-     * @return  string
+     * @return string
      */
     public function getAnchorTag()
     {
@@ -1161,6 +1168,7 @@ public function getTitle(): string
      * Sets the session-based last activity time.
      *
      * @param int $timestamp
+     * @return void
      */
     public function setSessionLastActivityTime($timestamp)
     {
diff --git a/wcfsetup/install/files/lib/data/user/UserProfileAction.class.php b/wcfsetup/install/files/lib/data/user/UserProfileAction.class.php
index 607c1280543..95989a19143 100644
--- a/wcfsetup/install/files/lib/data/user/UserProfileAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserProfileAction.class.php
@@ -42,18 +42,20 @@ class UserProfileAction extends UserAction
 
     /**
      * user profile object
-     * @var UserProfile
+     * @var ?UserProfile
      */
     public $userProfile;
 
     /**
      * uploaded file
-     * @var UploadFile
+     * @var ?UploadFile
      */
     public $uploadFile;
 
     /**
      * Validates parameters for signature preview.
+     *
+     * @return void
      */
     public function validateGetMessagePreview()
     {
@@ -63,8 +65,8 @@ public function validateGetMessagePreview()
     /**
      * Returns a rendered signature preview.
      *
-     * @return  array
-     * @throws  UserInputException
+     * @return array{message: string, raw: string}
+     * @throws UserInputException
      */
     public function getMessagePreview()
     {
@@ -107,7 +109,8 @@ public function getMessagePreview()
     /**
      * Validates detailed activity point list
      *
-     * @throws  UserInputException
+     * @return void
+     * @throws UserInputException
      */
     public function validateGetDetailedActivityPointList()
     {
@@ -124,7 +127,7 @@ public function validateGetDetailedActivityPointList()
     /**
      * Returns detailed activity point list.
      *
-     * @return  array
+     * @return array{template: string, userID: int}
      */
     public function getDetailedActivityPointList()
     {
@@ -167,8 +170,9 @@ public function getDetailedActivityPointList()
     /**
      * Validates parameters to begin profile inline editing.
      *
-     * @throws  PermissionDeniedException
-     * @throws  UserInputException
+     * @return void
+     * @throws PermissionDeniedException
+     * @throws UserInputException
      */
     public function validateBeginEdit()
     {
@@ -193,7 +197,7 @@ public function validateBeginEdit()
     /**
      * Begins profile inline editing.
      *
-     * @return  array
+     * @return array{template: string}
      */
     public function beginEdit()
     {
@@ -211,7 +215,8 @@ public function beginEdit()
     /**
      * Validates parameters to save changes to user profile.
      *
-     * @throws  PermissionDeniedException
+     * @return void
+     * @throws PermissionDeniedException
      */
     public function validateSave()
     {
@@ -232,7 +237,7 @@ public function validateSave()
     /**
      * Saves changes to user profile.
      *
-     * @return  array
+     * @return array{success: bool, template: string}
      */
     public function save()
     {
@@ -319,6 +324,8 @@ public function save()
 
     /**
      * Updates user ranks.
+     *
+     * @return void
      */
     public function updateUserRank()
     {
@@ -376,6 +383,8 @@ public function updateUserRank()
 
     /**
      * Updates user online markings.
+     *
+     * @return void
      */
     public function updateUserOnlineMarking()
     {
@@ -462,6 +471,8 @@ public function updateUserOnlineMarking()
 
     /**
      * Updates the special trophies.
+     *
+     * @return void
      */
     public function updateSpecialTrophies()
     {
@@ -502,9 +513,8 @@ public function updateSpecialTrophies()
     /**
      * Returns the user option handler object.
      *
-     * @param User $user
      * @param bool $editMode
-     * @return  UserOptionHandler
+     * @return UserOptionHandler
      */
     protected function getOptionHandler(User $user, $editMode = true)
     {
diff --git a/wcfsetup/install/files/lib/data/user/UserProfileList.class.php b/wcfsetup/install/files/lib/data/user/UserProfileList.class.php
index f54c72556a5..8820bf30e64 100644
--- a/wcfsetup/install/files/lib/data/user/UserProfileList.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserProfileList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfile     current()
- * @method  UserProfile[]       getObjects()
- * @method  UserProfile|null    getSingleObject()
- * @method  UserProfile|null    search($objectID)
- * @property    UserProfile[] $objects
+ * @extends UserList<UserProfile>
  */
 class UserProfileList extends UserList
 {
diff --git a/wcfsetup/install/files/lib/data/user/UserRegistrationAction.class.php b/wcfsetup/install/files/lib/data/user/UserRegistrationAction.class.php
index dd288435327..2508148e725 100644
--- a/wcfsetup/install/files/lib/data/user/UserRegistrationAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/UserRegistrationAction.class.php
@@ -20,6 +20,8 @@ class UserRegistrationAction extends UserAction
 
     /**
      * Validates the validate username function.
+     *
+     * @return void
      */
     public function validateValidateUsername()
     {
@@ -28,6 +30,8 @@ public function validateValidateUsername()
 
     /**
      * Validates the validate email address function.
+     *
+     * @return void
      */
     public function validateValidateEmailAddress()
     {
@@ -37,7 +41,7 @@ public function validateValidateEmailAddress()
     /**
      * Validates the given username.
      *
-     * @return  array
+     * @return array{isValid: bool, error?: string}
      */
     public function validateUsername()
     {
@@ -63,7 +67,7 @@ public function validateUsername()
     /**
      * Validates given email address.
      *
-     * @return  array
+     * @return array{isValid: bool, error?: string}
      */
     public function validateEmailAddress()
     {
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEvent.class.php b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEvent.class.php
index 2f76948799e..268e1f68355 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEvent.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEvent.class.php
@@ -17,7 +17,7 @@
  * @property-read   int|null $languageID     id of the language of the related object or null if the object has no specific language
  * @property-read   int $userID         id of the user who has triggered the user activity event
  * @property-read   int $time           timestamp at which the user activity event has been triggered
- * @property-read   array $additionalData     array with additional data of the user activity event
+ * @property-read   mixed[] $additionalData     array with additional data of the user activity event
  */
 class UserActivityEvent extends DatabaseObject
 {
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventAction.class.php b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventAction.class.php
index cf87a5ed1ac..6797d4f276f 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventAction.class.php
@@ -19,9 +19,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserActivityEvent       create()
- * @method  UserActivityEventEditor[]   getObjects()
- * @method  UserActivityEventEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserActivityEvent, UserActivityEventEditor>
  */
 class UserActivityEventAction extends AbstractDatabaseObjectAction
 {
@@ -37,6 +35,8 @@ class UserActivityEventAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates parameters to load recent activity entries.
+     *
+     * @return void
      */
     public function validateLoad()
     {
@@ -65,7 +65,11 @@ public function validateLoad()
     /**
      * Loads a list of recent activity entries.
      *
-     * @return  array
+     * @return array{
+     *  lastEventID: int,
+     *  lastEventTime: int,
+     *  template: string,
+     * }|array{}
      */
     public function load()
     {
@@ -135,9 +139,14 @@ public function load()
 
     /**
      * Does nothing.
+     *
+     * @return void
      */
     public function validateSwitchContext() {}
 
+    /**
+     * @return void
+     */
     public function switchContext()
     {
         /** @noinspection PhpUndefinedFieldInspection */
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventEditor.class.php b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventEditor.class.php
index 16357be2883..c59b19848e2 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserActivityEvent   create(array $parameters = [])
- * @method      UserActivityEvent   getDecoratedObject()
  * @mixin       UserActivityEvent
+ * @extends DatabaseObjectEditor<UserActivityEvent>
  */
 class UserActivityEventEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventList.class.php b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventList.class.php
index a5df0cbf99c..ea0593f64c2 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventList.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/UserActivityEventList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserActivityEvent       current()
- * @method  UserActivityEvent[]     getObjects()
- * @method  UserActivityEvent|null      getSingleObject()
- * @method  UserActivityEvent|null      search($objectID)
- * @property    UserActivityEvent[] $objects
+ * @extends DatabaseObjectList<UserActivityEvent>
  */
-class UserActivityEventList extends DatabaseObjectList
-{
-}
+class UserActivityEventList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEvent.class.php b/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEvent.class.php
index e50a620daf8..da294173f28 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEvent.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEvent.class.php
@@ -16,8 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserActivityEvent   getDecoratedObject()
  * @mixin   UserActivityEvent
+ * @extends DatabaseObjectDecorator<UserActivityEvent>
  */
 class ViewableUserActivityEvent extends DatabaseObjectDecorator
 {
@@ -52,7 +52,7 @@ class ViewableUserActivityEvent extends DatabaseObjectDecorator
 
     /**
      * user profile
-     * @var UserProfile
+     * @var ?UserProfile
      */
     protected $userProfile;
 
@@ -74,6 +74,8 @@ class ViewableUserActivityEvent extends DatabaseObjectDecorator
 
     /**
      * Marks this event as accessible for current user.
+     *
+     * @return void
      */
     public function setIsAccessible()
     {
@@ -83,7 +85,7 @@ public function setIsAccessible()
     /**
      * Returns true if event is accessible by current user.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAccessible()
     {
@@ -92,6 +94,8 @@ public function isAccessible()
 
     /**
      * Marks this event as orphaned.
+     *
+     * @return void
      */
     public function setIsOrphaned()
     {
@@ -101,7 +105,7 @@ public function setIsOrphaned()
     /**
      * Returns true if event is orphaned (associated object removed).
      *
-     * @return  bool
+     * @return bool
      */
     public function isOrphaned()
     {
@@ -111,7 +115,7 @@ public function isOrphaned()
     /**
      * Sets user profile.
      *
-     * @param UserProfile $userProfile
+     * @return void
      * @deprecated  3.0
      */
     public function setUserProfile(UserProfile $userProfile)
@@ -122,7 +126,7 @@ public function setUserProfile(UserProfile $userProfile)
     /**
      * Returns user profile.
      *
-     * @return  UserProfile
+     * @return UserProfile
      */
     public function getUserProfile()
     {
@@ -138,6 +142,7 @@ public function getUserProfile()
      *
      * @param string $description
      * @param bool $isRawHtml
+     * @return void
      */
     public function setDescription($description, $isRawHtml = false)
     {
@@ -148,7 +153,7 @@ public function setDescription($description, $isRawHtml = false)
     /**
      * Returns event text.
      *
-     * @return  string
+     * @return string
      */
     public function getDescription()
     {
@@ -159,6 +164,7 @@ public function getDescription()
      * Sets event title.
      *
      * @param string $title
+     * @return void
      */
     public function setTitle($title)
     {
@@ -168,7 +174,7 @@ public function setTitle($title)
     /**
      * Returns event title.
      *
-     * @return  string
+     * @return string
      */
     public function getTitle()
     {
@@ -178,7 +184,7 @@ public function getTitle()
     /**
      * Returns the object type name.
      *
-     * @return  string
+     * @return string
      */
     public function getObjectTypeName()
     {
@@ -188,8 +194,8 @@ public function getObjectTypeName()
     /**
      * Returns true if event description contains raw html.
      *
-     * @return      bool
-     * @since       3.1
+     * @return bool
+     * @since 3.1
      */
     public function isRawHtml()
     {
diff --git a/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEventList.class.php b/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEventList.class.php
index 31d84f4cf41..745e5ed48ad 100644
--- a/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEventList.class.php
+++ b/wcfsetup/install/files/lib/data/user/activity/event/ViewableUserActivityEventList.class.php
@@ -114,7 +114,7 @@ public function getLastEventTime()
     /**
      * Validates event permissions and returns a list of orphaned event ids.
      *
-     * @return  int[]
+     * @return list<int>
      */
     public function validateEvents()
     {
@@ -137,6 +137,7 @@ public function validateEvents()
      * Truncates the items in object list to given number of items.
      *
      * @param int $limit
+     * @return void
      */
     public function truncate($limit)
     {
diff --git a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureAction.class.php b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureAction.class.php
index d3eb0f69984..1816ee2adf0 100644
--- a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserAuthenticationFailure       create()
- * @method  UserAuthenticationFailureEditor[]   getObjects()
- * @method  UserAuthenticationFailureEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserAuthenticationFailure, UserAuthenticationFailureEditor>
  */
 class UserAuthenticationFailureAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureEditor.class.php b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureEditor.class.php
index 2085a3608d8..cb9ef8f17f4 100644
--- a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserAuthenticationFailure   create(array $parameters = [])
- * @method      UserAuthenticationFailure   getDecoratedObject()
  * @mixin       UserAuthenticationFailure
+ * @extends DatabaseObjectEditor<UserAuthenticationFailure>
  */
 class UserAuthenticationFailureEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureList.class.php b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureList.class.php
index 8c991ffa3af..f3c01f58dc3 100644
--- a/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureList.class.php
+++ b/wcfsetup/install/files/lib/data/user/authentication/failure/UserAuthenticationFailureList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserAuthenticationFailure       current()
- * @method  UserAuthenticationFailure[]     getObjects()
- * @method  UserAuthenticationFailure|null      getSingleObject()
- * @method  UserAuthenticationFailure|null      search($objectID)
- * @property    UserAuthenticationFailure[] $objects
+ * @extends DatabaseObjectList<UserAuthenticationFailure>
  */
-class UserAuthenticationFailureList extends DatabaseObjectList
-{
-}
+class UserAuthenticationFailureList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarAction.class.php b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarAction.class.php
index 7879d2d3fad..7a571dac1a8 100644
--- a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarAction.class.php
@@ -11,12 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserAvatar      create()
- * @method  UserAvatarEditor[]  getObjects()
- * @method  UserAvatarEditor    getSingleObject()
- *
+ * @extends AbstractDatabaseObjectAction<UserAvatar, UserAvatarEditor>
  * @deprecated 6.2
  */
-class UserAvatarAction extends AbstractDatabaseObjectAction
-{
-}
+class UserAvatarAction extends AbstractDatabaseObjectAction {}
diff --git a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarEditor.class.php b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarEditor.class.php
index 6fb548a14be..7f89a215e37 100644
--- a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarEditor.class.php
@@ -13,9 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserAvatar  create(array $parameters = [])
- * @method      UserAvatar  getDecoratedObject()
  * @mixin       UserAvatar
+ * @extends DatabaseObjectEditor<UserAvatar>
  *
  * @deprecated 6.2
  */
@@ -49,7 +48,9 @@ public static function deleteAll(array $objectIDs = [])
                 WHERE   avatarID IN (" . \str_repeat('?,', \count($objectIDs) - 1) . "?)";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute($objectIDs);
+        // @phpstan-ignore argument.templateType
         while ($avatar = $statement->fetchObject(self::$baseClass)) {
+            /** @var UserAvatar $avatar */
             $editor = new self($avatar);
             $editor->deleteFiles();
         }
@@ -59,6 +60,8 @@ public static function deleteAll(array $objectIDs = [])
 
     /**
      * Deletes avatar files.
+     *
+     * @return void
      */
     public function deleteFiles()
     {
diff --git a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarList.class.php b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarList.class.php
index 6ede57d0170..a9448dc6b97 100644
--- a/wcfsetup/install/files/lib/data/user/avatar/UserAvatarList.class.php
+++ b/wcfsetup/install/files/lib/data/user/avatar/UserAvatarList.class.php
@@ -11,14 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserAvatar      current()
- * @method  UserAvatar[]        getObjects()
- * @method  UserAvatar|null     getSingleObject()
- * @method  UserAvatar|null     search($objectID)
- * @property    UserAvatar[] $objects
- *
+ * @extends DatabaseObjectList<UserAvatar>
  * @deprecated 6.2
  */
-class UserAvatarList extends DatabaseObjectList
-{
-}
+class UserAvatarList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/cover/photo/IUserCoverPhoto.class.php b/wcfsetup/install/files/lib/data/user/cover/photo/IUserCoverPhoto.class.php
index ada928087f6..c0125e223f0 100644
--- a/wcfsetup/install/files/lib/data/user/cover/photo/IUserCoverPhoto.class.php
+++ b/wcfsetup/install/files/lib/data/user/cover/photo/IUserCoverPhoto.class.php
@@ -13,6 +13,8 @@ interface IUserCoverPhoto
 {
     /**
      * Deletes this cover photo.
+     *
+     * @return void
      */
     public function delete();
 
diff --git a/wcfsetup/install/files/lib/data/user/cover/photo/UserCoverPhoto.class.php b/wcfsetup/install/files/lib/data/user/cover/photo/UserCoverPhoto.class.php
index ed64cef41cb..edc44baf2c9 100644
--- a/wcfsetup/install/files/lib/data/user/cover/photo/UserCoverPhoto.class.php
+++ b/wcfsetup/install/files/lib/data/user/cover/photo/UserCoverPhoto.class.php
@@ -72,6 +72,11 @@ public function getObjectID(): int
 
     /**
      * Returns the minimum and maximum dimensions for cover photos.
+     *
+     * @return array{
+     *  max: array{height: int, width: int},
+     *  min: array{height: int, width: int},
+     * }
      */
     public static function getCoverPhotoDimensions(): array
     {
@@ -90,7 +95,6 @@ public static function getCoverPhotoDimensions(): array
     /**
      * Returns the location of a user's cover photo before WCF6.2.
      */
-    /** @noinspection PhpUndefinedFieldInspection */
     public static function getLegacyLocation(User $user, bool $forceWebP): ?string
     {
         if (!$user->coverPhotoHash || !$user->coverPhotoExtension) {
diff --git a/wcfsetup/install/files/lib/data/user/follow/UserFollowAction.class.php b/wcfsetup/install/files/lib/data/user/follow/UserFollowAction.class.php
index 18d15778a6a..c423c3c2fe4 100644
--- a/wcfsetup/install/files/lib/data/user/follow/UserFollowAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/follow/UserFollowAction.class.php
@@ -23,9 +23,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserFollow      create()
- * @method  UserFollowEditor[]  getObjects()
- * @method  UserFollowEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserFollow, UserFollowEditor>
  */
 class UserFollowAction extends AbstractDatabaseObjectAction implements IGroupedUserListAction
 {
@@ -35,14 +33,14 @@ class UserFollowAction extends AbstractDatabaseObjectAction implements IGroupedU
     protected $allowGuestAccess = ['getGroupedUserList'];
 
     /**
-     * user profile object
-     * @var UserProfile
+     * @var ?UserProfile
      */
     public $userProfile;
 
     /**
      * Validates given parameters.
      *
+     * @return void
      * @deprecated 6.1 use `wcf\action\UserFollowAction` instead
      */
     public function validateFollow()
@@ -73,7 +71,7 @@ public function validateFollow()
     /**
      * Follows a user.
      *
-     * @return  array
+     * @return array{following: 1}
      * @deprecated 6.1 use `wcf\action\UserFollowAction` instead
      */
     public function follow()
@@ -87,7 +85,7 @@ public function follow()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      * @deprecated 6.1 use `wcf\action\UserFollowAction` instead
      */
     public function validateUnfollow()
@@ -98,7 +96,7 @@ public function validateUnfollow()
     /**
      * Stops following a user.
      *
-     * @return  array
+     * @return array{following: 0}
      * @deprecated 6.1 use `wcf\action\UserFollowAction` instead
      */
     public function unfollow()
@@ -189,7 +187,7 @@ public function getGroupedUserList()
                 WHERE   followUserID = ?";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$this->parameters['userID']]);
-        $pageCount = \ceil($statement->fetchSingleColumn() / 20);
+        $pageCount = (int)\ceil($statement->fetchSingleColumn() / 20);
 
         // get user ids
         $sql = "SELECT  userID
diff --git a/wcfsetup/install/files/lib/data/user/follow/UserFollowEditor.class.php b/wcfsetup/install/files/lib/data/user/follow/UserFollowEditor.class.php
index c8d81a0c09c..f9d2ae497b0 100644
--- a/wcfsetup/install/files/lib/data/user/follow/UserFollowEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/follow/UserFollowEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserFollow  create(array $parameters = [])
- * @method      UserFollow  getDecoratedObject()
  * @mixin       UserFollow
+ * @extends DatabaseObjectEditor<UserFollow>
  */
 class UserFollowEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/follow/UserFollowList.class.php b/wcfsetup/install/files/lib/data/user/follow/UserFollowList.class.php
index 0ac1817c11a..1514c9b657e 100644
--- a/wcfsetup/install/files/lib/data/user/follow/UserFollowList.class.php
+++ b/wcfsetup/install/files/lib/data/user/follow/UserFollowList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserFollow      current()
- * @method  UserFollow[]        getObjects()
- * @method  UserFollow|null     getSingleObject()
- * @method  UserFollow|null     search($objectID)
- * @property    UserFollow[] $objects
+ * @extends DatabaseObjectList<UserFollow>
  */
-class UserFollowList extends DatabaseObjectList
-{
-}
+class UserFollowList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/follow/UserFollowingAction.class.php b/wcfsetup/install/files/lib/data/user/follow/UserFollowingAction.class.php
index bbd6df8204a..518ee51e208 100644
--- a/wcfsetup/install/files/lib/data/user/follow/UserFollowingAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/follow/UserFollowingAction.class.php
@@ -54,7 +54,7 @@ public function getGroupedUserList()
                 WHERE   userID = ?";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$this->parameters['userID']]);
-        $pageCount = \ceil($statement->fetchSingleColumn() / 20);
+        $pageCount = (int)\ceil($statement->fetchSingleColumn() / 20);
 
         // get user ids
         $sql = "SELECT  followUserID
diff --git a/wcfsetup/install/files/lib/data/user/group/I18nUserGroupList.class.php b/wcfsetup/install/files/lib/data/user/group/I18nUserGroupList.class.php
index c2a91ca2cf5..e67fa2cf001 100644
--- a/wcfsetup/install/files/lib/data/user/group/I18nUserGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/I18nUserGroupList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method  UserGroup       current()
- * @method  UserGroup[]     getObjects()
- * @method  UserGroup|null      getSingleObject()
- * @method  UserGroup|null      search($objectID)
- * @property    UserGroup[] $objects
+ * @extends I18nDatabaseObjectList<UserGroup>
  */
 class I18nUserGroupList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/Team.class.php b/wcfsetup/install/files/lib/data/user/group/Team.class.php
index f6a56ac6d42..8d66d0367d7 100644
--- a/wcfsetup/install/files/lib/data/user/group/Team.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/Team.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroup   getDecoratedObject()
  * @mixin   UserGroup
+ * @extends DatabaseObjectDecorator<UserGroup>
  */
 class Team extends DatabaseObjectDecorator
 {
@@ -31,7 +31,7 @@ class Team extends DatabaseObjectDecorator
     /**
      * Adds a new member.
      *
-     * @param UserProfile $user
+     * @return void
      */
     public function addMember(UserProfile $user)
     {
@@ -41,7 +41,7 @@ public function addMember(UserProfile $user)
     /**
      * Returns the list of user group members
      *
-     * @return  UserProfile[]
+     * @return UserProfile[]
      */
     public function getMembers()
     {
diff --git a/wcfsetup/install/files/lib/data/user/group/UserGroup.class.php b/wcfsetup/install/files/lib/data/user/group/UserGroup.class.php
index eb9ac58b6cc..4caa133409d 100644
--- a/wcfsetup/install/files/lib/data/user/group/UserGroup.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/UserGroup.class.php
@@ -86,7 +86,7 @@ class UserGroup extends DatabaseObject implements ITitledObject
 
     /**
      * group options of this group
-     * @var mixed[][]
+     * @var array<string, mixed>
      */
     protected $groupOptions;
 
@@ -271,8 +271,8 @@ public function canCopy()
     /**
      * Returns true if the given groups are accessible for the active user.
      *
-     * @param array $groupIDs
-     * @return  bool
+     * @param int[] $groupIDs
+     * @return bool
      */
     public static function isAccessibleGroup(array $groupIDs = [])
     {
@@ -283,7 +283,7 @@ public static function isAccessibleGroup(array $groupIDs = [])
             ));
         }
 
-        if (empty($groupIDs)) {
+        if ($groupIDs === []) {
             return false;
         }
 
@@ -301,7 +301,7 @@ public static function isAccessibleGroup(array $groupIDs = [])
      *
      * @param int[] $groupTypes
      * @param int[] $invalidGroupTypes
-     * @return  UserGroup[]
+     * @return UserGroup[]
      */
     public static function getAccessibleGroups(array $groupTypes = [], array $invalidGroupTypes = [])
     {
@@ -321,8 +321,8 @@ public static function getAccessibleGroups(array $groupTypes = [], array $invali
      *
      * @param int[] $groupTypes
      * @param int[] $invalidGroupTypes
-     * @return  UserGroup[]
-     * @since       5.2
+     * @return UserGroup[]
+     * @since 5.2
      */
     public static function getSortedAccessibleGroups(array $groupTypes = [], array $invalidGroupTypes = [])
     {
@@ -340,7 +340,7 @@ public static function getSortedAccessibleGroups(array $groupTypes = [], array $
      *  b) This is the 'Owner' group.
      *  c) The group can access all groups (the 'Owner' group does not count).
      *
-     * @return  bool
+     * @return bool
      */
     public function isAdminGroup()
     {
@@ -363,7 +363,7 @@ public function isAdminGroup()
     /**
      * Returns true if the current group is a moderator-group.
      *
-     * @return  bool
+     * @return bool
      */
     public function isModGroup()
     {
@@ -377,6 +377,8 @@ public function isModGroup()
 
     /**
      * Loads the group cache.
+     *
+     * @return void
      */
     protected static function getCache()
     {
@@ -388,7 +390,7 @@ protected static function getCache()
     /**
      * Returns true if this group is accessible for the active user.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAccessible()
     {
@@ -406,7 +408,7 @@ public function __toString(): string
     /**
      * Returns the name of this user group.
      *
-     * @return  string
+     * @return string
      */
     public function getName()
     {
@@ -420,6 +422,7 @@ public function getName()
      * in the same request.
      *
      * @param string $name
+     * @return void
      */
     public function setName($name)
     {
@@ -429,7 +432,7 @@ public function setName($name)
     /**
      * Returns true if current user may delete this group.
      *
-     * @return  bool
+     * @return bool
      */
     public function isDeletable()
     {
@@ -459,7 +462,7 @@ public function isDeletable()
     /**
      * Returns true if current user may edit this group.
      *
-     * @return  bool
+     * @return bool
      */
     public function isEditable()
     {
@@ -480,7 +483,7 @@ public function isEditable()
      * Returns the value of the group option with the given name.
      *
      * @param string $name
-     * @return  mixed
+     * @return mixed|null
      */
     public function getGroupOption($name)
     {
@@ -510,9 +513,7 @@ public function getGroupOption($name)
             }
         }
 
-        if (isset($this->groupOptions[$name])) {
-            return $this->groupOptions[$name];
-        }
+        return $this->groupOptions[$name] ?? null;
     }
 
     /**
@@ -526,8 +527,8 @@ public function getTitle(): string
     /**
      * Returns the user group description in the active user's language.
      *
-     * @return  string
-     * @since   5.2
+     * @return string
+     * @since 5.2
      */
     public function getDescription()
     {
@@ -620,7 +621,7 @@ public static function getOwnerPermissions()
     /**
      * Returns the owner group's id unless no group was promoted yet due to backwards compatibility.
      *
-     * @return int|null
+     * @return ?int
      * @since 5.2
      */
     public static function getOwnerGroupID()
@@ -636,7 +637,8 @@ public static function getOwnerGroupID()
      * Sorts the given user groups alphabetically.
      *
      * @param UserGroup[] $userGroups
-     * @since       5.3
+     * @return void
+     * @since 5.3
      */
     public static function sortGroups(array &$userGroups)
     {
diff --git a/wcfsetup/install/files/lib/data/user/group/UserGroupAction.class.php b/wcfsetup/install/files/lib/data/user/group/UserGroupAction.class.php
index b66c737f847..ecf053f1b83 100644
--- a/wcfsetup/install/files/lib/data/user/group/UserGroupAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/UserGroupAction.class.php
@@ -11,8 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupEditor[]   getObjects()
- * @method  UserGroupEditor     getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserGroup, UserGroupEditor>
  */
 class UserGroupAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/UserGroupEditor.class.php b/wcfsetup/install/files/lib/data/user/group/UserGroupEditor.class.php
index 956438785e0..a2cb30115c1 100644
--- a/wcfsetup/install/files/lib/data/user/group/UserGroupEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/UserGroupEditor.class.php
@@ -18,8 +18,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroup   getDecoratedObject()
  * @mixin   UserGroup
+ * @extends DatabaseObjectEditor<UserGroup>
+ * @implements IEditableCachedObject<UserGroup>
  */
 class UserGroupEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -30,14 +31,11 @@ class UserGroupEditor extends DatabaseObjectEditor implements IEditableCachedObj
 
     /**
      * @inheritDoc
-     * @return  UserGroup
      */
     public static function create(array $parameters = [])
     {
-        /** @var UserGroup $group */
         $group = parent::create($parameters);
 
-        // update accessible groups
         self::updateAccessibleGroups($group->groupID);
 
         return $group;
@@ -66,11 +64,12 @@ public static function deleteAll(array $objectIDs = [])
     /**
      * Removes user to group assignments.
      *
-     * @param array $groupIDs
+     * @param int[] $groupIDs
+     * @return void
      */
     protected static function removeGroupAssignments(array $groupIDs)
     {
-        if (empty($groupIDs)) {
+        if ($groupIDs === []) {
             return;
         }
 
@@ -85,11 +84,12 @@ protected static function removeGroupAssignments(array $groupIDs)
     /**
      * Removes group option values.
      *
-     * @param array $groupIDs
+     * @param int[] $groupIDs
+     * @return void
      */
     protected static function removeOptionValues(array $groupIDs)
     {
-        if (empty($groupIDs)) {
+        if ($groupIDs === []) {
             return;
         }
 
@@ -104,7 +104,8 @@ protected static function removeOptionValues(array $groupIDs)
     /**
      * Updates group options.
      *
-     * @param array $groupOptions
+     * @param array<int, mixed> $groupOptions
+     * @return void
      */
     public function updateGroupOptions(array $groupOptions = [])
     {
@@ -131,6 +132,7 @@ public function updateGroupOptions(array $groupOptions = [])
      *
      * @param int $groupID this group is added or deleted in the value
      * @param bool $delete flag for group deletion
+     * @return void
      * @throws  SystemException
      */
     protected static function updateAccessibleGroups($groupID, $delete = false)
diff --git a/wcfsetup/install/files/lib/data/user/group/UserGroupList.class.php b/wcfsetup/install/files/lib/data/user/group/UserGroupList.class.php
index 308bc60e641..e045a2ac233 100644
--- a/wcfsetup/install/files/lib/data/user/group/UserGroupList.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/UserGroupList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroup       current()
- * @method  UserGroup[]     getObjects()
- * @method  UserGroup|null      getSingleObject()
- * @method  UserGroup|null      search($objectID)
- * @property    UserGroup[] $objects
+ * @extends DatabaseObjectList<UserGroup>
  */
 class UserGroupList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentAction.class.php b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentAction.class.php
index 20c73a0b9e0..f900e1b5e2d 100644
--- a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupAssignment     create()
- * @method  UserGroupAssignmentEditor[] getObjects()
- * @method  UserGroupAssignmentEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserGroupAssignment, UserGroupAssignmentEditor>
  */
 class UserGroupAssignmentAction extends AbstractDatabaseObjectAction implements IToggleAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentEditor.class.php b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentEditor.class.php
index ec55a5abcdf..d7cb60e334b 100644
--- a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentEditor.class.php
@@ -15,9 +15,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserGroupAssignment create(array $parameters = [])
- * @method      UserGroupAssignment getDecoratedObject()
  * @mixin       UserGroupAssignment
+ * @extends DatabaseObjectEditor<UserGroupAssignment>
+ * @implements IEditableCachedObject<UserGroupAssignment>
  */
 class UserGroupAssignmentEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentList.class.php b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentList.class.php
index b4350f5feda..2a4f2022ae2 100644
--- a/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentList.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/assignment/UserGroupAssignmentList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupAssignment     current()
- * @method  UserGroupAssignment[]       getObjects()
- * @method  UserGroupAssignment|null    getSingleObject()
- * @method  UserGroupAssignment|null    search($objectID)
- * @property    UserGroupAssignment[] $objects
+ * @extends DatabaseObjectList<UserGroupAssignment>
  */
-class UserGroupAssignmentList extends DatabaseObjectList
-{
-}
+class UserGroupAssignmentList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionAction.class.php b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionAction.class.php
index d392455a55f..cf09d6009e6 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupOption         create()
- * @method  UserGroupOptionEditor[]     getObjects()
- * @method  UserGroupOptionEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserGroupOption, UserGroupOptionEditor>
  */
 class UserGroupOptionAction extends AbstractDatabaseObjectAction
 {
@@ -27,6 +25,8 @@ class UserGroupOptionAction extends AbstractDatabaseObjectAction
 
     /**
      * Updates option values for given option id.
+     *
+     * @return void
      */
     public function updateValues()
     {
diff --git a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionEditor.class.php b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionEditor.class.php
index 9922865b8ae..f9e4cc1d5e3 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserGroupOption     create(array $parameters = [])
- * @method      UserGroupOption     getDecoratedObject()
  * @mixin       UserGroupOption
+ * @extends DatabaseObjectEditor<UserGroupOption>
+ * @implements IEditableCachedObject<UserGroupOption>
  */
 class UserGroupOptionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionList.class.php b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionList.class.php
index acf2555b3e5..dfc774812a8 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionList.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/UserGroupOptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupOption     current()
- * @method  UserGroupOption[]   getObjects()
- * @method  UserGroupOption|null    getSingleObject()
- * @method  UserGroupOption|null    search($objectID)
- * @property    UserGroupOption[] $objects
+ * @extends DatabaseObjectList<UserGroupOption>
  */
 class UserGroupOptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryAction.class.php b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryAction.class.php
index 2fce7220445..25f67b4238b 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupOptionCategory         create()
- * @method  UserGroupOptionCategoryEditor[]     getObjects()
- * @method  UserGroupOptionCategoryEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserGroupOptionCategory, UserGroupOptionCategoryEditor>
  */
 class UserGroupOptionCategoryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryEditor.class.php b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryEditor.class.php
index a4e972a8981..79724cf1a36 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserGroupOptionCategory     create(array $parameters = [])
- * @method      UserGroupOptionCategory     getDecoratedObject()
  * @mixin       UserGroupOptionCategory
+ * @extends DatabaseObjectEditor<UserGroupOptionCategory>
  */
 class UserGroupOptionCategoryEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryList.class.php b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryList.class.php
index 19163b2abb7..232e8c28684 100644
--- a/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/user/group/option/category/UserGroupOptionCategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserGroupOptionCategory     current()
- * @method  UserGroupOptionCategory[]   getObjects()
- * @method  UserGroupOptionCategory|null    getSingleObject()
- * @method  UserGroupOptionCategory|null    search($objectID)
- * @property    UserGroupOptionCategory[] $objects
+ * @extends DatabaseObjectList<UserGroupOptionCategory>
  */
 class UserGroupOptionCategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreAction.class.php b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreAction.class.php
index 3e67d8e96fd..730c99a8fc3 100644
--- a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreAction.class.php
@@ -25,16 +25,19 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserIgnore      create()
- * @method  UserIgnoreEditor[]  getObjects()
- * @method  UserIgnoreEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserIgnore, UserIgnoreEditor>
  */
 class UserIgnoreAction extends AbstractDatabaseObjectAction
 {
+    /**
+     * @var ?IFormDocument
+     */
     protected $form;
 
     /**
      * Validates the 'ignore' action.
+     *
+     * @return void
      */
     public function validateIgnore()
     {
@@ -66,7 +69,7 @@ public function validateIgnore()
     /**
      * Ignores a user.
      *
-     * @return  array
+     * @return array{isIgnoredUser: 1}
      */
     public function ignore()
     {
@@ -120,6 +123,8 @@ public function ignore()
 
     /**
      * Validates the 'unignore' action.
+     *
+     * @return void
      */
     public function validateUnignore()
     {
@@ -134,7 +139,7 @@ public function validateUnignore()
     /**
      * Unignores a user.
      *
-     * @return  array
+     * @return array{isIgnoredUser: 0}
      */
     public function unignore()
     {
@@ -151,6 +156,9 @@ public function unignore()
         return ['isIgnoredUser' => 0];
     }
 
+    /**
+     * @return void
+     */
     public function validateGetDialog()
     {
         $this->readInteger('userID');
@@ -168,6 +176,9 @@ public function validateGetDialog()
         }
     }
 
+    /**
+     * @return array{dialog: string, formId: string}
+     */
     public function getDialog()
     {
         $form = $this->getForm();
@@ -178,6 +189,9 @@ public function getDialog()
         ];
     }
 
+    /**
+     * @return void
+     */
     public function validateSubmitDialog()
     {
         $this->validateGetDialog();
@@ -189,6 +203,9 @@ public function validateSubmitDialog()
         $this->getForm()->validate();
     }
 
+    /**
+     * @return array{dialog: string, formId: string}|array{isIgnoredUser: 0|1}
+     */
     public function submitDialog()
     {
         if ($this->getForm()->hasValidationErrors()) {
diff --git a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreEditor.class.php b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreEditor.class.php
index c1db0dfaa2f..19d6bf92a1b 100644
--- a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserIgnore  create(array $parameters = [])
- * @method      UserIgnore  getDecoratedObject()
  * @mixin       UserIgnore
+ * @extends DatabaseObjectEditor<UserIgnore>
  */
 class UserIgnoreEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreList.class.php b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreList.class.php
index a9fd0af5225..b8a69a5f5a0 100644
--- a/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreList.class.php
+++ b/wcfsetup/install/files/lib/data/user/ignore/UserIgnoreList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserIgnore      current()
- * @method  UserIgnore[]        getObjects()
- * @method  UserIgnore|null     getSingleObject()
- * @method  UserIgnore|null     search($objectID)
- * @property    UserIgnore[] $objects
+ * @extends DatabaseObjectList<UserIgnore>
  */
-class UserIgnoreList extends DatabaseObjectList
-{
-}
+class UserIgnoreList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItem.class.php b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItem.class.php
index 63c58cba5ab..1e61f801974 100644
--- a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItem.class.php
+++ b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItem.class.php
@@ -123,6 +123,8 @@ public function getController()
 
     /**
      * Parses controller name.
+     *
+     * @return void
      */
     protected function parseController()
     {
diff --git a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemAction.class.php b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemAction.class.php
index 3f83080b649..990f0bcaace 100644
--- a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserMenuItem        create()
- * @method  UserMenuItemEditor[]    getObjects()
- * @method  UserMenuItemEditor  getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserMenuItem, UserMenuItemEditor>
  */
 class UserMenuItemAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemEditor.class.php b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemEditor.class.php
index 555aa9eef70..89bc5ea9672 100644
--- a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserMenuItem    create(array $parameters = [])
- * @method      UserMenuItem    getDecoratedObject()
  * @mixin       UserMenuItem
+ * @extends DatabaseObjectEditor<UserMenuItem>
  */
 class UserMenuItemEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemList.class.php b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemList.class.php
index 241fe502ff0..f82f43ada10 100644
--- a/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemList.class.php
+++ b/wcfsetup/install/files/lib/data/user/menu/item/UserMenuItemList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserMenuItem        current()
- * @method  UserMenuItem[]      getObjects()
- * @method  UserMenuItem|null   getSingleObject()
- * @method  UserMenuItem|null   search($objectID)
- * @property    UserMenuItem[] $objects
+ * @extends DatabaseObjectList<UserMenuItem>
  */
-class UserMenuItemList extends DatabaseObjectList
-{
-}
+class UserMenuItemList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/notification/UserNotification.class.php b/wcfsetup/install/files/lib/data/user/notification/UserNotification.class.php
index 0cb52ead22a..f80efa7d88b 100644
--- a/wcfsetup/install/files/lib/data/user/notification/UserNotification.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/UserNotification.class.php
@@ -25,7 +25,7 @@
  * @property-read   int $time           timestamp at which the user notification has been created
  * @property-read   int $mailNotified       is 0 has not be notified by mail about the user notification, otherwise 1
  * @property-read   int $confirmTime        timestamp at which the user notification has been marked as confirmed/read
- * @property-read   array $additionalData     array with additional data of the user notification event
+ * @property-read   mixed[] $additionalData     array with additional data of the user notification event
  */
 class UserNotification extends DatabaseObject
 {
diff --git a/wcfsetup/install/files/lib/data/user/notification/UserNotificationAction.class.php b/wcfsetup/install/files/lib/data/user/notification/UserNotificationAction.class.php
index 3429293f674..48c65d65903 100644
--- a/wcfsetup/install/files/lib/data/user/notification/UserNotificationAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/UserNotificationAction.class.php
@@ -21,9 +21,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserNotificationEditor[]    getObjects()
- * @method  UserNotificationEditor      getSingleObject()
- * @method UserNotification create()
+ * @extends AbstractDatabaseObjectAction<UserNotification, UserNotificationEditor>
  */
 class UserNotificationAction extends AbstractDatabaseObjectAction
 {
@@ -168,6 +166,18 @@ public function validateGetNotificationData(): void
     }
 
     /**
+     * @return array{
+     *  items: list<array{
+     *      content: string,
+     *      image: string,
+     *      isUnread: bool,
+     *      link: string,
+     *      objectId: int,
+     *      time: int,
+     *      usernames: string[],
+     *  }>,
+     *  totalCount: int,
+     * }
      * @since 5.5
      */
     public function getNotificationData(): array
@@ -219,6 +229,8 @@ public function getNotificationData(): array
 
     /**
      * Validates parameters to mark a notification as confirmed.
+     *
+     * @return void
      */
     public function validateMarkAsConfirmed()
     {
@@ -231,7 +243,7 @@ public function validateMarkAsConfirmed()
     /**
      * Marks a notification as confirmed.
      *
-     * @return  array
+     * @return array{markAsRead: int, totalCount: int}
      */
     public function markAsConfirmed()
     {
@@ -245,6 +257,8 @@ public function markAsConfirmed()
 
     /**
      * Validates parameters to mark all notifications of current user as confirmed.
+     *
+     * @return void
      */
     public function validateMarkAllAsConfirmed()
     {
@@ -254,7 +268,7 @@ public function validateMarkAllAsConfirmed()
     /**
      * Marks all notifications of current user as confirmed.
      *
-     * @return  bool[]
+     * @return array{markAllAsRead: bool}
      */
     public function markAllAsConfirmed()
     {
diff --git a/wcfsetup/install/files/lib/data/user/notification/UserNotificationEditor.class.php b/wcfsetup/install/files/lib/data/user/notification/UserNotificationEditor.class.php
index 9f7342fc75c..15452d144d5 100644
--- a/wcfsetup/install/files/lib/data/user/notification/UserNotificationEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/UserNotificationEditor.class.php
@@ -12,9 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserNotification    create(array $parameters = [])
- * @method      UserNotification    getDecoratedObject()
  * @mixin       UserNotification
+ * @extends DatabaseObjectEditor<UserNotification>
  */
 class UserNotificationEditor extends DatabaseObjectEditor
 {
@@ -26,6 +25,7 @@ class UserNotificationEditor extends DatabaseObjectEditor
     /**
      * Marks this notification as confirmed.
      *
+     * @return void
      * @deprecated 5.2 Please use `UserNotificationHandler::markAsConfirmedByIDs()` instead.
      */
     public function markAsConfirmed()
diff --git a/wcfsetup/install/files/lib/data/user/notification/UserNotificationList.class.php b/wcfsetup/install/files/lib/data/user/notification/UserNotificationList.class.php
index 93200fb42c9..f6dc65317d4 100644
--- a/wcfsetup/install/files/lib/data/user/notification/UserNotificationList.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/UserNotificationList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserNotification        current()
- * @method  UserNotification[]      getObjects()
- * @method  UserNotification|null       getSingleObject()
- * @method  UserNotification|null       search($objectID)
- * @property    UserNotification[] $objects
+ * @extends DatabaseObjectList<UserNotification>
  */
-class UserNotificationList extends DatabaseObjectList
-{
-}
+class UserNotificationList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventAction.class.php b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventAction.class.php
index 20fcc403c62..eab2a0fe175 100644
--- a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventAction.class.php
@@ -17,8 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserNotificationEventEditor[]   getObjects()
- * @method  UserNotificationEventEditor getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserNotificationEvent, UserNotificationEventEditor>
  */
 class UserNotificationEventAction extends AbstractDatabaseObjectAction
 {
@@ -61,6 +60,7 @@ public function create()
     /**
      * Validates the `testEvent` action.
      *
+     * @return void
      * @throws  PermissionDeniedException
      * @throws  UserInputException
      * @since   3.1
@@ -87,8 +87,11 @@ public function validateTestEvent()
     /**
      * Tests a certain user notification event by returning all possible notifications.
      *
-     * @return  array
-     * @since   3.1
+     * @return array{
+     *  eventID: int,
+     *  template: string,
+     * }
+     * @since 3.1
      */
     public function testEvent()
     {
diff --git a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventEditor.class.php b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventEditor.class.php
index a6df7aa14eb..8765f61a758 100644
--- a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserNotificationEvent   create(array $parameters = [])
- * @method      UserNotificationEvent   getDecoratedObject()
  * @mixin       UserNotificationEvent
+ * @extends DatabaseObjectEditor<UserNotificationEvent>
  */
 class UserNotificationEventEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventList.class.php b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventList.class.php
index 96ac1dc86c2..cf030d1b90e 100644
--- a/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventList.class.php
+++ b/wcfsetup/install/files/lib/data/user/notification/event/UserNotificationEventList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserNotificationEvent       current()
- * @method  UserNotificationEvent[]     getObjects()
- * @method  UserNotificationEvent|null  getSingleObject()
- * @method  UserNotificationEvent|null  search($objectID)
- * @property    UserNotificationEvent[] $objects
+ * @extends DatabaseObjectList<UserNotificationEvent>
  */
-class UserNotificationEventList extends DatabaseObjectList
-{
-}
+class UserNotificationEventList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchAction.class.php b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchAction.class.php
index 39e55271c05..8f1b5b5e4ad 100644
--- a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchAction.class.php
@@ -15,9 +15,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserObjectWatch         create()
- * @method  UserObjectWatchEditor[]     getObjects()
- * @method  UserObjectWatchEditor       getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserObjectWatch, UserObjectWatchEditor>
  */
 class UserObjectWatchAction extends AbstractDatabaseObjectAction
 {
@@ -35,6 +33,8 @@ class UserObjectWatchAction extends AbstractDatabaseObjectAction
 
     /**
      * Validates parameters to manage a subscription.
+     *
+     * @return void
      */
     public function validateManageSubscription()
     {
@@ -64,7 +64,7 @@ public function validateManageSubscription()
     /**
      * Returns a form to manage a subscription.
      *
-     * @return  array
+     * @return array{objectID: int, objectType: string, template: string}
      */
     public function manageSubscription()
     {
@@ -80,6 +80,8 @@ public function manageSubscription()
 
     /**
      * Validates parameters to save subscription state.
+     *
+     * @return void
      */
     public function validateSaveSubscription()
     {
@@ -91,6 +93,8 @@ public function validateSaveSubscription()
 
     /**
      * Saves subscription state.
+     *
+     * @return array{objectID: int, objectType: int, subscribe: 0|1|bool}
      */
     public function saveSubscription()
     {
@@ -132,6 +136,8 @@ public function saveSubscription()
 
     /**
      * Adds a subscription.
+     *
+     * @return void
      */
     public function subscribe()
     {
@@ -153,6 +159,8 @@ public function subscribe()
 
     /**
      * Removes a subscription.
+     *
+     * @return void
      */
     public function unsubscribe()
     {
@@ -179,6 +187,8 @@ public function unsubscribe()
 
     /**
      * Validates the subscribe action.
+     *
+     * @return void
      */
     protected function __validateSubscribe()
     {
@@ -207,6 +217,8 @@ protected function __validateSubscribe()
 
     /**
      * Validates the subscribe action.
+     *
+     * @return void
      */
     public function validateSubscribe()
     {
@@ -219,6 +231,8 @@ public function validateSubscribe()
 
     /**
      * Validates the unsubscribe action.
+     *
+     * @return void
      */
     public function validateUnsubscribe()
     {
diff --git a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchEditor.class.php b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchEditor.class.php
index 59cf4a29d30..a7bcd2a23d0 100644
--- a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserObjectWatch     create(array $parameters = [])
- * @method      UserObjectWatch     getDecoratedObject()
  * @mixin       UserObjectWatch
+ * @extends DatabaseObjectEditor<UserObjectWatch>
  */
 class UserObjectWatchEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchList.class.php b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchList.class.php
index 164642c4e85..18900d9d6f6 100644
--- a/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchList.class.php
+++ b/wcfsetup/install/files/lib/data/user/object/watch/UserObjectWatchList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserObjectWatch     current()
- * @method  UserObjectWatch[]   getObjects()
- * @method  UserObjectWatch|null    getSingleObject()
- * @method  UserObjectWatch|null    search($objectID)
- * @property    UserObjectWatch[] $objects
+ * @extends DatabaseObjectList<UserObjectWatch>
  */
 class UserObjectWatchList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/online/UsersOnlineList.class.php b/wcfsetup/install/files/lib/data/user/online/UsersOnlineList.class.php
index 7ba92fd5748..45d652816ab 100644
--- a/wcfsetup/install/files/lib/data/user/online/UsersOnlineList.class.php
+++ b/wcfsetup/install/files/lib/data/user/online/UsersOnlineList.class.php
@@ -20,11 +20,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOnline      current()
- * @method  UserOnline[]        getObjects()
- * @method  UserOnline|null         getSingleObject()
- * @method  UserOnline|null         search($objectID)
- * @property    UserOnline[] $objects
+ * @extends SessionList<UserOnline>
  */
 class UsersOnlineList extends SessionList
 {
@@ -37,7 +33,7 @@ class UsersOnlineList extends SessionList
 
     /**
      * users online stats
-     * @var array
+     * @var array{total: int, invisible: int, members: int, guests: int}
      */
     public $stats = [
         'total' => 0,
@@ -48,7 +44,7 @@ class UsersOnlineList extends SessionList
 
     /**
      * users online markings
-     * @var array
+     * @var ?string[]
      */
     public $usersOnlineMarkings;
 
@@ -86,6 +82,7 @@ public function readObjects()
         $this->indexToObject = $this->objects = [];
 
         foreach ($objects as $object) {
+            // @phpstan-ignore argument.type
             $object = new UserOnline(new User(null, null, $object));
             if (!$object->userID || self::isVisibleUser($object)) {
                 $this->objects[$object->sessionID] = $object;
@@ -100,6 +97,8 @@ public function readObjects()
 
     /**
      * Fetches users online stats.
+     *
+     * @return void
      */
     public function readStats()
     {
@@ -138,7 +137,7 @@ public function readStats()
     /**
      * Returns a list of the users online markings.
      *
-     * @return  array
+     * @return string[]
      */
     public function getUsersOnlineMarkings()
     {
@@ -166,6 +165,8 @@ public function getUsersOnlineMarkings()
 
     /**
      * Checks the users online record.
+     *
+     * @return void
      */
     public function checkRecord()
     {
diff --git a/wcfsetup/install/files/lib/data/user/option/UserOption.class.php b/wcfsetup/install/files/lib/data/user/option/UserOption.class.php
index 6cf5fd93663..209e12d8999 100644
--- a/wcfsetup/install/files/lib/data/user/option/UserOption.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/UserOption.class.php
@@ -128,6 +128,7 @@ public function getTitle(): string
      * Sets target user object.
      *
      * @param User $user
+     * @return void
      */
     public function setUser(User $user)
     {
@@ -221,6 +222,7 @@ public function canDelete()
      * Allows modifications of editable option.
      *
      * @param int $editableOption
+     * @return void
      */
     public function modifyEditableOption($editableOption)
     {
@@ -231,6 +233,7 @@ public function modifyEditableOption($editableOption)
      * Allows modifications of visible option.
      *
      * @param int $visibleOption
+     * @return void
      */
     public function modifyVisibleOption($visibleOption)
     {
diff --git a/wcfsetup/install/files/lib/data/user/option/UserOptionAction.class.php b/wcfsetup/install/files/lib/data/user/option/UserOptionAction.class.php
index 599a899bca3..5ae9f5fd219 100644
--- a/wcfsetup/install/files/lib/data/user/option/UserOptionAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/UserOptionAction.class.php
@@ -11,9 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOption      create()
- * @method  UserOptionEditor[]  getObjects()
- * @method  UserOptionEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserOption, UserOptionEditor>
  */
 class UserOptionAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/option/UserOptionEditor.class.php b/wcfsetup/install/files/lib/data/user/option/UserOptionEditor.class.php
index b4e5c11d2ab..e2d6e7f3b4d 100644
--- a/wcfsetup/install/files/lib/data/user/option/UserOptionEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/UserOptionEditor.class.php
@@ -14,8 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOption  getDecoratedObject()
  * @mixin   UserOption
+ * @extends DatabaseObjectEditor<UserOption>
+ * @implements IEditableCachedObject<UserOption>
  */
 class UserOptionEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -98,6 +99,8 @@ public static function deleteAll(array $objectIDs = [])
 
     /**
      * Disables this option.
+     *
+     * @return void
      */
     public function disable()
     {
@@ -108,6 +111,7 @@ public function disable()
      * Enables this option.
      *
      * @param bool $enable
+     * @return void
      */
     public function enable($enable = true)
     {
@@ -124,7 +128,14 @@ public function enable($enable = true)
      * Determines the needed sql statement to modify column definitions.
      *
      * @param string $optionType
-     * @return  array       column definition
+     * @return array{
+     *  autoIncrement: bool,
+     *  key: false,
+     *  notNull: bool,
+     *  type: string,
+     *  default?: int|float|string,
+     *  length?: int,
+     * } column definition
      */
     public static function getColumnDefinition($optionType)
     {
diff --git a/wcfsetup/install/files/lib/data/user/option/UserOptionList.class.php b/wcfsetup/install/files/lib/data/user/option/UserOptionList.class.php
index 35f326c53ee..df7b294d160 100644
--- a/wcfsetup/install/files/lib/data/user/option/UserOptionList.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/UserOptionList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOption      current()
- * @method  UserOption[]        getObjects()
- * @method  UserOption|null     getSingleObject()
- * @method  UserOption|null     search($objectID)
- * @property    UserOption[] $objects
+ * @extends DatabaseObjectList<UserOption>
  */
 class UserOptionList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/option/ViewableUserOption.class.php b/wcfsetup/install/files/lib/data/user/option/ViewableUserOption.class.php
index 230b55d300e..95b07163adf 100644
--- a/wcfsetup/install/files/lib/data/user/option/ViewableUserOption.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/ViewableUserOption.class.php
@@ -18,8 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOption  getDecoratedObject()
  * @mixin   UserOption
+ * @extends DatabaseObjectDecorator<UserOption>
  */
 class ViewableUserOption extends DatabaseObjectDecorator
 {
@@ -49,7 +49,7 @@ class ViewableUserOption extends DatabaseObjectDecorator
     /**
      * Sets option values for a specific user.
      *
-     * @param User $user
+     * @return void
      */
     public function setOptionValue(User $user)
     {
diff --git a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryAction.class.php b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryAction.class.php
index 8bb79190e10..d3b840f97d9 100644
--- a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOptionCategory      create()
- * @method  UserOptionCategoryEditor[]  getObjects()
- * @method  UserOptionCategoryEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserOptionCategory, UserOptionCategoryEditor>
  */
 class UserOptionCategoryAction extends AbstractDatabaseObjectAction
 {
diff --git a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryEditor.class.php b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryEditor.class.php
index afbb4587646..e55194be1c4 100644
--- a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryEditor.class.php
@@ -13,8 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOptionCategory  getDecoratedObject()
  * @mixin   UserOptionCategory
+ * @extends DatabaseObjectEditor<UserOptionCategory>
+ * @implements IEditableCachedObject<UserOptionCategory>
  */
 class UserOptionCategoryEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -34,9 +35,7 @@ public static function create(array $parameters = [])
             $parameters['packageID'] = PACKAGE_ID;
         }
 
-        $object = parent::create($parameters);
-        \assert($object instanceof UserOptionCategory);
-        return $object;
+        return parent::create($parameters);
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryList.class.php b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryList.class.php
index 12205f24559..e29bfa454c8 100644
--- a/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryList.class.php
+++ b/wcfsetup/install/files/lib/data/user/option/category/UserOptionCategoryList.class.php
@@ -11,11 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserOptionCategory      current()
- * @method  UserOptionCategory[]        getObjects()
- * @method  UserOptionCategory|null     getSingleObject()
- * @method  UserOptionCategory|null     search($objectID)
- * @property    UserOptionCategory[] $objects
+ * @extends DatabaseObjectList<UserOptionCategory>
  */
 class UserOptionCategoryList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemAction.class.php b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemAction.class.php
index ed72ba8a8d0..41b2eec6116 100644
--- a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemAction.class.php
@@ -20,9 +20,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfileMenuItem     create()
- * @method  UserProfileMenuItemEditor[] getObjects()
- * @method  UserProfileMenuItemEditor   getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserProfileMenuItem, UserProfileMenuItemEditor>
  */
 class UserProfileMenuItemAction extends AbstractDatabaseObjectAction implements ISortableAction
 {
@@ -44,6 +42,8 @@ class UserProfileMenuItemAction extends AbstractDatabaseObjectAction implements
 
     /**
      * Validates menu item.
+     *
+     * @return void
      */
     public function validateGetContent()
     {
@@ -71,6 +71,8 @@ public function validateGetContent()
 
     /**
      * Returns content for given menu item.
+     *
+     * @return array{template: string}
      */
     public function getContent()
     {
diff --git a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemEditor.class.php b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemEditor.class.php
index 6620732d0db..9ec7d5f20c4 100644
--- a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemEditor.class.php
@@ -14,8 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfileMenuItem getDecoratedObject()
  * @mixin   UserProfileMenuItem
+ * @extends DatabaseObjectEditor<UserProfileMenuItem>
+ * @implements IEditableCachedObject<UserProfileMenuItem>
  */
 class UserProfileMenuItemEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
@@ -30,11 +31,10 @@ class UserProfileMenuItemEditor extends DatabaseObjectEditor implements IEditabl
      */
     public static function create(array $parameters = [])
     {
-        // calculate show order
         $parameters['showOrder'] = self::getShowOrder($parameters['showOrder'] ?? 0);
 
         $object = parent::create($parameters);
-        \assert($object instanceof UserProfileMenuItem);
+
         return $object;
     }
 
@@ -69,6 +69,7 @@ public function delete()
      * Updates show order for current menu item.
      *
      * @param int $showOrder
+     * @return void
      */
     protected function updateShowOrder($showOrder)
     {
diff --git a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemList.class.php b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemList.class.php
index c50ab3d0703..ce8cbce785e 100644
--- a/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemList.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/menu/item/UserProfileMenuItemList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfileMenuItem     current()
- * @method  UserProfileMenuItem[]       getObjects()
- * @method  UserProfileMenuItem|null    getSingleObject()
- * @method  UserProfileMenuItem|null    search($objectID)
- * @property    UserProfileMenuItem[] $objects
+ * @extends DatabaseObjectList<UserProfileMenuItem>
  */
-class UserProfileMenuItemList extends DatabaseObjectList
-{
-}
+class UserProfileMenuItemList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorAction.class.php b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorAction.class.php
index c557e8b5239..6e9ab760085 100644
--- a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorAction.class.php
@@ -18,9 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfileVisitor      create()
- * @method  UserProfileVisitorEditor[]  getObjects()
- * @method  UserProfileVisitorEditor    getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserProfileVisitor, UserProfileVisitorEditor>
  */
 class UserProfileVisitorAction extends AbstractDatabaseObjectAction implements IGroupedUserListAction
 {
@@ -67,7 +65,7 @@ public function getGroupedUserList()
                 WHERE   ownerID = ?";
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$this->parameters['userID']]);
-        $pageCount = \ceil($statement->fetchSingleColumn() / 20);
+        $pageCount = (int)\ceil($statement->fetchSingleColumn() / 20);
 
         // get user ids
         $sql = "SELECT      userID
@@ -95,6 +93,7 @@ public function getGroupedUserList()
 
     /**
      * Inserts a new visitor if it does not already exist, or updates it if it does.
+     * @return void
      * @since       5.2
      */
     public function registerVisitor()
diff --git a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorEditor.class.php b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorEditor.class.php
index 14af841871d..022f272733a 100644
--- a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorEditor.class.php
@@ -11,9 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserProfileVisitor  create(array $parameters = [])
- * @method      UserProfileVisitor  getDecoratedObject()
  * @mixin       UserProfileVisitor
+ * @extends DatabaseObjectEditor<UserProfileVisitor>
  */
 class UserProfileVisitorEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorList.class.php b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorList.class.php
index 1852452c4d1..871ee4b8fe0 100644
--- a/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorList.class.php
+++ b/wcfsetup/install/files/lib/data/user/profile/visitor/UserProfileVisitorList.class.php
@@ -14,11 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserProfile     current()
- * @method  UserProfile[]       getObjects()
- * @method  UserProfile|null    getSingleObject()
- * @method  UserProfile|null    search($objectID)
- * @property    UserProfile[] $objects
+ * @extends DatabaseObjectList<UserProfile>
  */
 class UserProfileVisitorList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/rank/I18nUserRankList.class.php b/wcfsetup/install/files/lib/data/user/rank/I18nUserRankList.class.php
index 7ea78a4ab7b..0b8be07a888 100644
--- a/wcfsetup/install/files/lib/data/user/rank/I18nUserRankList.class.php
+++ b/wcfsetup/install/files/lib/data/user/rank/I18nUserRankList.class.php
@@ -12,11 +12,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.0
  *
- * @method      UserRank        current()
- * @method      UserRank[]      getObjects()
- * @method      UserRank|null   getSingleObject()
- * @method      UserRank|null   search($objectID)
- * @property    UserRank[]      $objects
+ * @extends I18nDatabaseObjectList<UserRank>
  */
 class I18nUserRankList extends I18nDatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/data/user/rank/UserRank.class.php b/wcfsetup/install/files/lib/data/user/rank/UserRank.class.php
index fd8186b577c..087285f3ad1 100644
--- a/wcfsetup/install/files/lib/data/user/rank/UserRank.class.php
+++ b/wcfsetup/install/files/lib/data/user/rank/UserRank.class.php
@@ -69,6 +69,7 @@ public function showTitle()
 
     /**
      * @see UploadFormField::updatedObject()
+     * @return list<string>
      */
     public function getRankImageFileUploadFileLocations(): array
     {
diff --git a/wcfsetup/install/files/lib/data/user/rank/UserRankAction.class.php b/wcfsetup/install/files/lib/data/user/rank/UserRankAction.class.php
index cb970220b2c..e50ba463c41 100644
--- a/wcfsetup/install/files/lib/data/user/rank/UserRankAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/rank/UserRankAction.class.php
@@ -14,9 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserRankEditor[]    getObjects()
- * @method  UserRankEditor      getSingleObject()
- * @property-read UserRankEditor[] $objects
+ * @extends AbstractDatabaseObjectAction<UserRank, UserRankEditor>
  */
 class UserRankAction extends AbstractDatabaseObjectAction
 {
@@ -142,6 +140,9 @@ public function delete()
         return $count;
     }
 
+    /**
+     * @return array<string, string>
+     */
     public function getI18nSaveTypes(): array
     {
         return ['rankTitle' => 'wcf.user.rank.userRank\d+'];
diff --git a/wcfsetup/install/files/lib/data/user/rank/UserRankEditor.class.php b/wcfsetup/install/files/lib/data/user/rank/UserRankEditor.class.php
index e57f20efeb5..4fe9a9ca6ae 100644
--- a/wcfsetup/install/files/lib/data/user/rank/UserRankEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/rank/UserRankEditor.class.php
@@ -13,9 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method static UserRank    create(array $parameters = [])
- * @method      UserRank    getDecoratedObject()
- * @mixin       UserRank
+ * @mixin UserRank
+ * @extends DatabaseObjectEditor<UserRank>
+ * @implements IEditableCachedObject<UserRank>
  */
 class UserRankEditor extends DatabaseObjectEditor implements IEditableCachedObject
 {
diff --git a/wcfsetup/install/files/lib/data/user/rank/UserRankList.class.php b/wcfsetup/install/files/lib/data/user/rank/UserRankList.class.php
index 3d153147f0e..8b11dee7de7 100644
--- a/wcfsetup/install/files/lib/data/user/rank/UserRankList.class.php
+++ b/wcfsetup/install/files/lib/data/user/rank/UserRankList.class.php
@@ -11,12 +11,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserRank    current()
- * @method  UserRank[]  getObjects()
- * @method  UserRank|null   getSingleObject()
- * @method  UserRank|null   search($objectID)
- * @property    UserRank[] $objects
+ * @extends DatabaseObjectList<UserRank>
  */
-class UserRankList extends DatabaseObjectList
-{
-}
+class UserRankList extends DatabaseObjectList {}
diff --git a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyAction.class.php b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyAction.class.php
index 8fad2d49290..8556ba7d8a8 100644
--- a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyAction.class.php
+++ b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyAction.class.php
@@ -25,8 +25,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  UserTrophyEditor[]      getObjects()
- * @method  UserTrophyEditor        getSingleObject()
+ * @extends AbstractDatabaseObjectAction<UserTrophy, UserTrophyEditor>
  */
 class UserTrophyAction extends AbstractDatabaseObjectAction
 {
@@ -188,6 +187,8 @@ public function delete()
 
     /**
      * Validates the getGroupedUserTrophyList method.
+     *
+     * @return void
      */
     public function validateGetGroupedUserTrophyList()
     {
@@ -215,6 +216,8 @@ public function validateGetGroupedUserTrophyList()
 
     /**
      * Returns a viewable user trophy list for a specific user.
+     *
+     * @return array{pageCount: int, title: string, template: string}
      */
     public function getGroupedUserTrophyList()
     {
@@ -246,7 +249,7 @@ public function getGroupedUserTrophyList()
         $userTrophyList->sqlLimit = 10;
         $userTrophyList->sqlOffset = ($this->parameters['pageNo'] - 1) * 10;
         $userTrophyList->sqlOrderBy = 'time DESC';
-        $pageCount = \ceil($userTrophyList->countObjects() / 10);
+        $pageCount = (int)\ceil($userTrophyList->countObjects() / 10);
         $userTrophyList->readObjects();
 
         return [
diff --git a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyEditor.class.php b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyEditor.class.php
index 656020f5f24..7b7597b1527 100644
--- a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyEditor.class.php
+++ b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyEditor.class.php
@@ -12,6 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  * @mixin   UserTrophy
+ * @extends DatabaseObjectEditor<UserTrophy>
  */
 class UserTrophyEditor extends DatabaseObjectEditor
 {
diff --git a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyList.class.php b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyList.class.php
index 94c8d2b402f..ad1a73a2c14 100644
--- a/wcfsetup/install/files/lib/data/user/trophy/UserTrophyList.class.php
+++ b/wcfsetup/install/files/lib/data/user/trophy/UserTrophyList.class.php
@@ -12,11 +12,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  UserTrophy      current()
- * @method  UserTrophy[]        getObjects()
- * @method  UserTrophy|null     getSingleObject()
- * @method  UserTrophy|null     search($objectID)
- * @property    UserTrophy[] $objects
+ * @extends DatabaseObjectList<UserTrophy>
  */
 class UserTrophyList extends DatabaseObjectList
 {
diff --git a/wcfsetup/install/files/lib/event/acp/dashboard/box/PHPExtensionCollecting.class.php b/wcfsetup/install/files/lib/event/acp/dashboard/box/PHPExtensionCollecting.class.php
index 2339b1b9813..2af865c87b0 100644
--- a/wcfsetup/install/files/lib/event/acp/dashboard/box/PHPExtensionCollecting.class.php
+++ b/wcfsetup/install/files/lib/event/acp/dashboard/box/PHPExtensionCollecting.class.php
@@ -15,7 +15,7 @@
 final class PHPExtensionCollecting implements IPsr14Event
 {
     /**
-     * @var string[]|string[][]
+     * @var list<string|string[]>
      */
     private array $extensions = [
         'ctype',
@@ -34,8 +34,10 @@ final class PHPExtensionCollecting implements IPsr14Event
     /**
      * Registers a php extension.
      * If `$extension` is an array, the system checks whether one of the extensions is available.
+     *
+     * @param string|string[] $extension
      */
-    public function register(string | array $extension): void
+    public function register(string|array $extension): void
     {
         if (\in_array($extension, $this->extensions)) {
             return;
@@ -44,7 +46,7 @@ public function register(string | array $extension): void
     }
 
     /**
-     * @return string[]|string[][]
+     * @return list<string|string[]>
      */
     public function getExtensions(): array
     {
diff --git a/wcfsetup/install/files/lib/event/comment/CommentsDeleted.class.php b/wcfsetup/install/files/lib/event/comment/CommentsDeleted.class.php
index 18a76668e38..cf67cdc066d 100644
--- a/wcfsetup/install/files/lib/event/comment/CommentsDeleted.class.php
+++ b/wcfsetup/install/files/lib/event/comment/CommentsDeleted.class.php
@@ -12,11 +12,12 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
- *
- * @property-read Comment[] $comments
  */
 final class CommentsDeleted implements IPsr14Event
 {
+    /**
+     * @param Comment[] $comments
+     */
     public function __construct(
         public readonly array $comments,
     ) {
diff --git a/wcfsetup/install/files/lib/event/comment/response/ResponsesDeleted.class.php b/wcfsetup/install/files/lib/event/comment/response/ResponsesDeleted.class.php
index f1a7ace3b4c..a124a8545fc 100644
--- a/wcfsetup/install/files/lib/event/comment/response/ResponsesDeleted.class.php
+++ b/wcfsetup/install/files/lib/event/comment/response/ResponsesDeleted.class.php
@@ -12,11 +12,12 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
- *
- * @property-read CommentResponse[] $responses
  */
 final class ResponsesDeleted implements IPsr14Event
 {
+    /**
+     * @param CommentResponse[] $responses
+     */
     public function __construct(
         public readonly array $responses,
     ) {}
diff --git a/wcfsetup/install/files/lib/event/page/ContactFormSpamChecking.class.php b/wcfsetup/install/files/lib/event/page/ContactFormSpamChecking.class.php
index b744442090b..ae532968910 100644
--- a/wcfsetup/install/files/lib/event/page/ContactFormSpamChecking.class.php
+++ b/wcfsetup/install/files/lib/event/page/ContactFormSpamChecking.class.php
@@ -18,10 +18,12 @@ final class ContactFormSpamChecking implements IInterruptableEvent
 {
     use TInterruptableEvent;
 
+    /**
+     * @param string[] $messages
+     */
     public function __construct(
         public readonly string $email,
         public readonly string $ipAddress,
         public readonly array $messages,
-    ) {
-    }
+    ) {}
 }
diff --git a/wcfsetup/install/files/lib/event/user/RegistrationSpamChecking.class.php b/wcfsetup/install/files/lib/event/user/RegistrationSpamChecking.class.php
index 8137512020e..2f48041977d 100644
--- a/wcfsetup/install/files/lib/event/user/RegistrationSpamChecking.class.php
+++ b/wcfsetup/install/files/lib/event/user/RegistrationSpamChecking.class.php
@@ -15,6 +15,9 @@
  */
 final class RegistrationSpamChecking implements IPsr14Event
 {
+    /**
+     * @var string[]
+     */
     private array $matches = [];
 
     public function __construct(
@@ -34,6 +37,9 @@ public function addMatch(string $key): void
         $this->matches[$key] = $key;
     }
 
+    /**
+     * @return string[]
+     */
     public function getMatches(): array
     {
         return \array_values($this->matches);
diff --git a/wcfsetup/install/files/lib/event/worker/RebuildWorkerCollecting.class.php b/wcfsetup/install/files/lib/event/worker/RebuildWorkerCollecting.class.php
index 141d8b92ccc..49a840a3791 100644
--- a/wcfsetup/install/files/lib/event/worker/RebuildWorkerCollecting.class.php
+++ b/wcfsetup/install/files/lib/event/worker/RebuildWorkerCollecting.class.php
@@ -17,7 +17,10 @@
  */
 final class RebuildWorkerCollecting extends \wcf\system\worker\event\RebuildWorkerCollecting implements IPsr14Event
 {
-    private \SplPriorityQueue $queue;
+    /**
+     * @var \SplPriorityQueue<int, RegisteredWorker>
+     */
+    private readonly \SplPriorityQueue $queue;
 
     public function __construct()
     {
diff --git a/wcfsetup/install/files/lib/form/AbstractCaptchaForm.class.php b/wcfsetup/install/files/lib/form/AbstractCaptchaForm.class.php
index eb7a7ba2729..90e70483145 100644
--- a/wcfsetup/install/files/lib/form/AbstractCaptchaForm.class.php
+++ b/wcfsetup/install/files/lib/form/AbstractCaptchaForm.class.php
@@ -108,6 +108,8 @@ public function validate()
 
     /**
      * Validates the captcha.
+     *
+     * @return void
      */
     protected function validateCaptcha()
     {
diff --git a/wcfsetup/install/files/lib/form/AbstractForm.class.php b/wcfsetup/install/files/lib/form/AbstractForm.class.php
index 17388bc6520..0a0474f0572 100644
--- a/wcfsetup/install/files/lib/form/AbstractForm.class.php
+++ b/wcfsetup/install/files/lib/form/AbstractForm.class.php
@@ -40,6 +40,7 @@ abstract class AbstractForm extends AbstractPage implements IForm
     /**
      * database object action
      * @var AbstractDatabaseObjectAction
+     * @phpstan-ignore missingType.generics
      */
     public $objectAction;
 
@@ -114,8 +115,9 @@ public function validate()
     /**
      * Validates the form security token.
      *
-     * @throws  UserInputException  if the security token is invalid
-     * @since   5.2
+     * @return void
+     * @throws UserInputException  if the security token is invalid
+     * @since 5.2
      */
     protected function validateSecurityToken()
     {
@@ -136,6 +138,8 @@ public function save()
     /**
      * Calls the 'saved' event after the successful call of the save method.
      * This functions won't called automatically. You must do this manually, if you inherit AbstractForm.
+     *
+     * @return void
      */
     protected function saved()
     {
diff --git a/wcfsetup/install/files/lib/form/AbstractFormBuilderForm.class.php b/wcfsetup/install/files/lib/form/AbstractFormBuilderForm.class.php
index ebe57725b3d..3d32be708ca 100644
--- a/wcfsetup/install/files/lib/form/AbstractFormBuilderForm.class.php
+++ b/wcfsetup/install/files/lib/form/AbstractFormBuilderForm.class.php
@@ -23,13 +23,11 @@
 abstract class AbstractFormBuilderForm extends AbstractForm
 {
     /**
-     * form document
      * @var IFormDocument
      */
     public $form;
 
     /**
-     * name of the form document class
      * @var string
      */
     public $formClassName = FormDocument::class;
@@ -50,13 +48,17 @@ abstract class AbstractFormBuilderForm extends AbstractForm
     /**
      * name of the object action performing the form action
      * if not set, `$formAction` is used
-     * @var null|string
+     * @var ?string
      */
     public $objectActionName;
 
     /**
      * name of the object action class performing the form action
-     * @var string
+     *
+     * Note: Do not insert `AbstractDatabaseObjectAction` in the class-string,
+     * the generics will be extremely annoying in deriving classes.
+     *
+     * @var class-string
      */
     public $objectActionClass;
 
@@ -91,6 +93,8 @@ public function assignVariables()
 
     /**
      * Builds the form.
+     *
+     * @return void
      */
     public function buildForm()
     {
@@ -110,6 +114,8 @@ public function buildForm()
      *
      * This is the method that is intended to be overwritten by child classes
      * to add the form containers and fields.
+     *
+     * @return void
      */
     protected function createForm()
     {
@@ -221,6 +227,8 @@ public function saved()
 
     /**
      * Sets the action of the form.
+     *
+     * @return void
      */
     protected function setFormAction()
     {
@@ -240,6 +248,8 @@ protected function setFormAction()
 
     /**
      * Sets the form data based on the current form object.
+     *
+     * @return void
      */
     protected function setFormObjectData()
     {
diff --git a/wcfsetup/install/files/lib/form/AbstractModerationForm.class.php b/wcfsetup/install/files/lib/form/AbstractModerationForm.class.php
index d7443f20174..9a8bf3fd50d 100644
--- a/wcfsetup/install/files/lib/form/AbstractModerationForm.class.php
+++ b/wcfsetup/install/files/lib/form/AbstractModerationForm.class.php
@@ -31,7 +31,7 @@ abstract class AbstractModerationForm extends AbstractForm
 
     /**
      * data used for moderation queue update
-     * @var array
+     * @var mixed[]
      */
     public $data = [];
 
@@ -160,6 +160,8 @@ public function assignVariables()
 
     /**
      * Prepares update of moderation queue item.
+     *
+     * @return void
      */
     protected function prepareSave()
     {
diff --git a/wcfsetup/install/files/lib/form/IForm.class.php b/wcfsetup/install/files/lib/form/IForm.class.php
index c80ff869dbd..af39df44604 100644
--- a/wcfsetup/install/files/lib/form/IForm.class.php
+++ b/wcfsetup/install/files/lib/form/IForm.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\form;
 
+use Psr\Http\Message\ResponseInterface;
 use wcf\page\IPage;
 
 /**
@@ -15,21 +16,29 @@ interface IForm extends IPage
 {
     /**
      * Is called when the form was submitted.
+     *
+     * @return void
      */
     public function submit();
 
     /**
      * Validates form inputs.
+     *
+     * @return void|ResponseInterface
      */
     public function validate();
 
     /**
      * Saves the data of the form.
+     *
+     * @return void|ResponseInterface
      */
     public function save();
 
     /**
      * Reads the given form parameters.
+     *
+     * @return void|ResponseInterface
      */
     public function readFormParameters();
 }
diff --git a/wcfsetup/install/files/lib/form/LostPasswordForm.class.php b/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
index 780395d047d..8ee2982992d 100644
--- a/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
+++ b/wcfsetup/install/files/lib/form/LostPasswordForm.class.php
@@ -45,7 +45,7 @@ public function checkPermissions()
         parent::checkPermissions();
 
         if (!UserAuthenticationConfigurationFactory::getInstance()->getConfigration()->canChangePassword) {
-            return new IllegalLinkException();
+            throw new IllegalLinkException();
         }
     }
 
diff --git a/wcfsetup/install/files/lib/form/MessageForm.class.php b/wcfsetup/install/files/lib/form/MessageForm.class.php
index 45c2050549b..c8eb951a415 100644
--- a/wcfsetup/install/files/lib/form/MessageForm.class.php
+++ b/wcfsetup/install/files/lib/form/MessageForm.class.php
@@ -55,13 +55,13 @@ abstract class MessageForm extends AbstractCaptchaForm
 
     /**
      * list of available content languages
-     * @var Language[]
+     * @var array<int, Language>
      */
     public $availableContentLanguages = [];
 
     /**
      * list of default smilies
-     * @var Smiley[]
+     * @var array<int, Smiley>
      */
     public $defaultSmilies = [];
 
@@ -102,7 +102,7 @@ abstract class MessageForm extends AbstractCaptchaForm
 
     /**
      * list of smiley categories
-     * @var SmileyCategory[]
+     * @var array<int, SmileyCategory>
      */
     public $smileyCategories = [];
 
@@ -195,6 +195,8 @@ public function validate()
 
     /**
      * Validates the message subject.
+     *
+     * @return void
      */
     protected function validateSubject()
     {
@@ -215,6 +217,8 @@ protected function validateSubject()
 
     /**
      * Validates the message text.
+     *
+     * @return void
      */
     protected function validateText()
     {
@@ -261,6 +265,8 @@ protected function validateText()
 
     /**
      * Validates content language id.
+     *
+     * @return void
      */
     protected function validateContentLanguage()
     {
diff --git a/wcfsetup/install/files/lib/form/MultifactorAuthenticationForm.class.php b/wcfsetup/install/files/lib/form/MultifactorAuthenticationForm.class.php
index a15f2dd76e9..6d2e95ea561 100644
--- a/wcfsetup/install/files/lib/form/MultifactorAuthenticationForm.class.php
+++ b/wcfsetup/install/files/lib/form/MultifactorAuthenticationForm.class.php
@@ -149,6 +149,8 @@ public function saved()
 
     /**
      * Returns to the redirect url if given and to the landing page otherwise.
+     *
+     * @return void
      */
     protected function performRedirect()
     {
diff --git a/wcfsetup/install/files/lib/form/NotificationSettingsForm.class.php b/wcfsetup/install/files/lib/form/NotificationSettingsForm.class.php
index eefa47a690e..77fc35cfcbd 100644
--- a/wcfsetup/install/files/lib/form/NotificationSettingsForm.class.php
+++ b/wcfsetup/install/files/lib/form/NotificationSettingsForm.class.php
@@ -206,6 +206,8 @@ public function save()
 
     /**
      * Updates preferences for notification events.
+     *
+     * @return void
      */
     protected function updateActivationStates()
     {
diff --git a/wcfsetup/install/files/lib/form/ReauthenticationForm.class.php b/wcfsetup/install/files/lib/form/ReauthenticationForm.class.php
index e512acb8cb9..54001360a3b 100644
--- a/wcfsetup/install/files/lib/form/ReauthenticationForm.class.php
+++ b/wcfsetup/install/files/lib/form/ReauthenticationForm.class.php
@@ -97,6 +97,7 @@ public function saved()
     }
 
     /**
+     * @return void
      * @deprecated 5.5 Use `getRedirectResponse()` and the PSR-7 layer instead.
      */
     protected function performRedirect()
diff --git a/wcfsetup/install/files/lib/form/RegisterForm.class.php b/wcfsetup/install/files/lib/form/RegisterForm.class.php
index 8f935dd1256..4d03da9e82d 100644
--- a/wcfsetup/install/files/lib/form/RegisterForm.class.php
+++ b/wcfsetup/install/files/lib/form/RegisterForm.class.php
@@ -81,7 +81,7 @@ class RegisterForm extends UserAddForm
 
     /**
      * field names
-     * @var array
+     * @var array<string, string>
      */
     public $randomFieldNames = [];
 
@@ -190,7 +190,6 @@ public function readFormParameters()
      */
     protected function initOptionHandler()
     {
-        \assert($this->optionHandler instanceof UserOptionHandler);
         $this->optionHandler->setInRegistration();
         parent::initOptionHandler();
     }
@@ -309,7 +308,7 @@ public function show()
     }
 
     /**
-     * Validates the captcha.
+     * @return void
      */
     protected function validateCaptcha()
     {
diff --git a/wcfsetup/install/files/lib/form/SearchForm.class.php b/wcfsetup/install/files/lib/form/SearchForm.class.php
index 37639b3b142..cd384cc7193 100644
--- a/wcfsetup/install/files/lib/form/SearchForm.class.php
+++ b/wcfsetup/install/files/lib/form/SearchForm.class.php
@@ -5,6 +5,7 @@
 use wcf\data\search\keyword\SearchKeywordAction;
 use wcf\data\search\Search;
 use wcf\data\search\SearchAction;
+use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\exception\NamedUserException;
 use wcf\system\exception\PermissionDeniedException;
@@ -28,13 +29,11 @@
 class SearchForm extends AbstractCaptchaForm
 {
     /**
-     * list of additional conditions
-     * @var string[]
+     * @var array<string, PreparedStatementConditionBuilder>
      */
     public $additionalConditions = [];
 
     /**
-     * end date
      * @var string
      */
     public $endDate = '';
@@ -64,35 +63,33 @@ class SearchForm extends AbstractCaptchaForm
 
     /**
      * list of search results
-     * @var array
+     * @var list<array{objectID: int, objectType: string}>
      */
     public $results = [];
 
     /**
-     * @inheritDoc
+     * @var string
      */
     public $sortField = '';
 
     /**
-     * @inheritDoc
+     * @var string
      */
     public $sortOrder = '';
 
     /**
-     * user id
      * @var int
      */
     public $userID = 0;
 
     /**
-     * username
      * @var string
      */
     public $username = '';
 
     /**
      * parameters used for previous search
-     * @var array
+     * @var mixed[]
      */
     public $searchData = [];
 
@@ -103,8 +100,7 @@ class SearchForm extends AbstractCaptchaForm
     public $searchID = 0;
 
     /**
-     * PreparedStatementConditionBuilder object
-     * @var \wcf\system\database\util\PreparedStatementConditionBuilder
+     * @var PreparedStatementConditionBuilder
      */
     public $searchIndexCondition;
 
@@ -115,13 +111,11 @@ class SearchForm extends AbstractCaptchaForm
     public $searchHash = '';
 
     /**
-     * selected object types
      * @var string[]
      */
     public $selectedObjectTypes = [];
 
     /**
-     * start date
      * @var string
      */
     public $startDate = '';
@@ -342,6 +336,8 @@ public function validate()
 
     /**
      * Throws a NamedUserException on search failure.
+     *
+     * @return never
      */
     public function throwNoMatchesException()
     {
@@ -493,6 +489,8 @@ public function show()
 
     /**
      * Sets the conditions for a search in the table of the selected object types.
+     *
+     * @return void
      */
     protected function getConditions()
     {
@@ -558,7 +556,7 @@ protected function getConditions()
     /**
      * Returns user ids.
      *
-     * @return  int[]
+     * @return int[]
      */
     public function getUserIDs()
     {
diff --git a/wcfsetup/install/files/lib/form/SignatureEditForm.class.php b/wcfsetup/install/files/lib/form/SignatureEditForm.class.php
index 715a316b3ac..bd20a999fda 100644
--- a/wcfsetup/install/files/lib/form/SignatureEditForm.class.php
+++ b/wcfsetup/install/files/lib/form/SignatureEditForm.class.php
@@ -46,7 +46,7 @@ class SignatureEditForm extends MessageForm
     public $neededModules = ['MODULE_USER_SIGNATURE'];
 
     /**
-     * @inheritDoc
+     * @var bool
      */
     public $showSignatureSetting = false;
 
diff --git a/wcfsetup/install/files/lib/form/UserSearchForm.class.php b/wcfsetup/install/files/lib/form/UserSearchForm.class.php
index fe830b06a36..4116d0c8df6 100644
--- a/wcfsetup/install/files/lib/form/UserSearchForm.class.php
+++ b/wcfsetup/install/files/lib/form/UserSearchForm.class.php
@@ -62,7 +62,7 @@ class UserSearchForm extends UserOptionListForm
 
     /**
      * option tree
-     * @var array
+     * @var mixed[]
      */
     public $optionTree = [];
 
@@ -105,6 +105,8 @@ public function readData()
 
     /**
      * Reads option tree on page init.
+     *
+     * @return void
      */
     protected function readOptionTree()
     {
@@ -167,6 +169,8 @@ public function validate()
 
     /**
      * Search for users which fit to the search values.
+     *
+     * @return void
      */
     protected function search()
     {
@@ -199,6 +203,8 @@ protected function search()
 
     /**
      * Builds the static conditions.
+     *
+     * @return void
      */
     protected function buildStaticConditions()
     {
@@ -209,6 +215,8 @@ protected function buildStaticConditions()
 
     /**
      * Builds the dynamic conditions.
+     *
+     * @return void
      */
     protected function buildDynamicConditions()
     {
diff --git a/wcfsetup/install/files/lib/http/Helper.class.php b/wcfsetup/install/files/lib/http/Helper.class.php
index 47eed9c3963..44dd0d85dfd 100644
--- a/wcfsetup/install/files/lib/http/Helper.class.php
+++ b/wcfsetup/install/files/lib/http/Helper.class.php
@@ -108,6 +108,7 @@ public static function getPreferredContentType(RequestInterface $request, array
      * schema. Missing parameters or values that cannot be casted to the
      * requested type will yield a `MappingError`.
      *
+     * @param mixed[] $queryParameters
      * @throws MappingError
      */
     public static function mapQueryParameters(array $queryParameters, string $schema): mixed
@@ -131,6 +132,7 @@ public static function mapQueryParameters(array $queryParameters, string $schema
      * Missing parameters or values that cannot be casted to the requested
      * type will yield a `MappingError`.
      *
+     * @param mixed[] $bodyParameters
      * @throws MappingError
      */
     public static function mapRequestBody(array $bodyParameters, string $schema): mixed
diff --git a/wcfsetup/install/files/lib/http/middleware/HandleAccessToken.class.php b/wcfsetup/install/files/lib/http/middleware/HandleAccessToken.class.php
index 7f0f38da908..4d9ae309fcb 100644
--- a/wcfsetup/install/files/lib/http/middleware/HandleAccessToken.class.php
+++ b/wcfsetup/install/files/lib/http/middleware/HandleAccessToken.class.php
@@ -6,9 +6,11 @@
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\MiddlewareInterface;
 use Psr\Http\Server\RequestHandlerInterface;
+use wcf\action\IAction;
 use wcf\data\user\User;
 use wcf\http\attribute\AllowAccessToken;
 use wcf\http\error\NotFoundHandler;
+use wcf\page\IPage;
 use wcf\system\request\RequestHandler;
 use wcf\system\session\SessionHandler;
 use wcf\system\WCF;
@@ -55,6 +57,9 @@ private function handleAccessToken(string $accessToken): bool
         return $this->checkAccessToken($accessToken);
     }
 
+    /**
+     * @param \ReflectionClass<object> $class
+     */
     private function hasAttribute(\ReflectionClass $class): bool
     {
         if ($class->getAttributes(AllowAccessToken::class) !== []) {
diff --git a/wcfsetup/install/files/lib/page/AbstractAuthedPage.class.php b/wcfsetup/install/files/lib/page/AbstractAuthedPage.class.php
index 38b4131b143..46a8e4438d2 100644
--- a/wcfsetup/install/files/lib/page/AbstractAuthedPage.class.php
+++ b/wcfsetup/install/files/lib/page/AbstractAuthedPage.class.php
@@ -46,6 +46,8 @@ public function readParameters()
 
     /**
      * Validates the access-token and performs the login.
+     *
+     * @return void
      */
     protected function checkAccessToken()
     {
diff --git a/wcfsetup/install/files/lib/page/AbstractGridViewPage.class.php b/wcfsetup/install/files/lib/page/AbstractGridViewPage.class.php
index 5720da625c5..baa20941e42 100644
--- a/wcfsetup/install/files/lib/page/AbstractGridViewPage.class.php
+++ b/wcfsetup/install/files/lib/page/AbstractGridViewPage.class.php
@@ -14,13 +14,22 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template TGridView of AbstractGridView
  */
 abstract class AbstractGridViewPage extends AbstractPage
 {
+    /**
+     * @var TGridView
+     */
     protected AbstractGridView $gridView;
     protected int $pageNo = 1;
     protected string $sortField = '';
     protected string $sortOrder = '';
+
+    /**
+     * @var mixed[]
+     */
     protected array $filters = [];
 
     #[\Override]
@@ -84,6 +93,8 @@ protected function initGridView(): void
 
     /**
      * Returns the grid view instance for the rendering of this page.
+     *
+     * @return TGridView
      */
     protected abstract function createGridView(): AbstractGridView;
 }
diff --git a/wcfsetup/install/files/lib/page/AbstractPage.class.php b/wcfsetup/install/files/lib/page/AbstractPage.class.php
index 14925b01f04..d5ecc2a8b47 100644
--- a/wcfsetup/install/files/lib/page/AbstractPage.class.php
+++ b/wcfsetup/install/files/lib/page/AbstractPage.class.php
@@ -375,6 +375,8 @@ public function show()
 
     /**
      * Sets the active menu item of the page.
+     *
+     * @return void
      */
     protected function setActiveMenuItem()
     {
@@ -386,6 +388,7 @@ protected function setActiveMenuItem()
     }
 
     /**
+     * @return void
      * @deprecated 6.1 handled by the `CheckForForceLogin` middleware
      */
     protected function forceLogin()
@@ -395,6 +398,7 @@ protected function forceLogin()
     /**
      * Calls setResponse() if the parameter implements the ResponseInterface.
      *
+     * @param mixed $response
      * @see AbstractPage::setPsr7Response()
      * @since 5.5
      */
diff --git a/wcfsetup/install/files/lib/page/AbstractSecurePage.class.php b/wcfsetup/install/files/lib/page/AbstractSecurePage.class.php
index 018ec7d82fc..0986d714f1b 100644
--- a/wcfsetup/install/files/lib/page/AbstractSecurePage.class.php
+++ b/wcfsetup/install/files/lib/page/AbstractSecurePage.class.php
@@ -23,6 +23,8 @@ public function readParameters()
 
     /**
      * Validates the security token.
+     *
+     * @return void
      */
     protected function checkSecurityToken()
     {
diff --git a/wcfsetup/install/files/lib/page/ArticleListPage.class.php b/wcfsetup/install/files/lib/page/ArticleListPage.class.php
index ce26c7d714f..b1008ff0d2e 100644
--- a/wcfsetup/install/files/lib/page/ArticleListPage.class.php
+++ b/wcfsetup/install/files/lib/page/ArticleListPage.class.php
@@ -21,6 +21,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends SortablePage<AccessibleArticleList>
  */
 class ArticleListPage extends SortablePage
 {
@@ -69,7 +71,7 @@ class ArticleListPage extends SortablePage
 
     /**
      * url parameters
-     * @var array
+     * @var array<string, mixed>
      */
     public $controllerParameters = ['application' => 'wcf'];
 
@@ -202,6 +204,9 @@ protected function initObjectList()
         }
     }
 
+    /**
+     * @return void
+     */
     protected function applyFilters()
     {
         if ($this->user) {
diff --git a/wcfsetup/install/files/lib/page/CategoryTrophyListPage.class.php b/wcfsetup/install/files/lib/page/CategoryTrophyListPage.class.php
index 25ffdf6f90e..6451eb0cf7e 100644
--- a/wcfsetup/install/files/lib/page/CategoryTrophyListPage.class.php
+++ b/wcfsetup/install/files/lib/page/CategoryTrophyListPage.class.php
@@ -4,7 +4,6 @@
 
 use wcf\data\trophy\category\TrophyCategory;
 use wcf\data\trophy\category\TrophyCategoryCache;
-use wcf\data\trophy\TrophyList;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\exception\PermissionDeniedException;
 use wcf\system\request\LinkHandler;
@@ -17,8 +16,6 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
- *
- * @property    TrophyList $objectList
  */
 class CategoryTrophyListPage extends TrophyListPage
 {
diff --git a/wcfsetup/install/files/lib/page/CmsPage.class.php b/wcfsetup/install/files/lib/page/CmsPage.class.php
index 7bbf0541717..48db550f864 100644
--- a/wcfsetup/install/files/lib/page/CmsPage.class.php
+++ b/wcfsetup/install/files/lib/page/CmsPage.class.php
@@ -53,10 +53,7 @@ public function readParameters()
         $metaData = RequestHandler::getInstance()->getActiveRequest()->getMetaData();
         if (isset($metaData['cms'], $metaData['cms']['pageID'])) {
             $this->pageID = $metaData['cms']['pageID'];
-
-            if (isset($metaData['cms']['languageID'])) {
-                $this->languageID = $metaData['cms']['languageID'];
-            }
+            $this->languageID = $metaData['cms']['languageID'];
 
             // check if the language has been disabled
             if ($this->languageID && LanguageFactory::getInstance()->getLanguage($this->languageID) === null) {
diff --git a/wcfsetup/install/files/lib/page/CombinedTaggedPage.class.php b/wcfsetup/install/files/lib/page/CombinedTaggedPage.class.php
index 16b0ae4bfa4..5327a54262d 100644
--- a/wcfsetup/install/files/lib/page/CombinedTaggedPage.class.php
+++ b/wcfsetup/install/files/lib/page/CombinedTaggedPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
@@ -22,6 +23,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
+ *
+ * @extends MultipleLinkPage<DatabaseObjectList<DatabaseObject>>
  */
 class CombinedTaggedPage extends MultipleLinkPage
 {
@@ -46,7 +49,7 @@ class CombinedTaggedPage extends MultipleLinkPage
     public $objectType;
 
     /**
-     * @var ICombinedTaggable
+     * @var ICombinedTaggable<DatabaseObjectList<DatabaseObject>>
      */
     public $processor;
 
diff --git a/wcfsetup/install/files/lib/page/DeletedContentListPage.class.php b/wcfsetup/install/files/lib/page/DeletedContentListPage.class.php
index 4a84c431d8a..81c021df51a 100644
--- a/wcfsetup/install/files/lib/page/DeletedContentListPage.class.php
+++ b/wcfsetup/install/files/lib/page/DeletedContentListPage.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\WCF;
@@ -12,6 +14,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends MultipleLinkPage<DatabaseObjectList<DatabaseObject>>
  */
 class DeletedContentListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/EditHistoryPage.class.php b/wcfsetup/install/files/lib/page/EditHistoryPage.class.php
index 55fb34df0e4..30644ea9242 100644
--- a/wcfsetup/install/files/lib/page/EditHistoryPage.class.php
+++ b/wcfsetup/install/files/lib/page/EditHistoryPage.class.php
@@ -57,6 +57,7 @@ class EditHistoryPage extends AbstractPage
 
     /**
      * differences between both versions
+     * @var ?mixed[]
      */
     public ?array $diff = null;
 
@@ -128,7 +129,7 @@ public function readParameters(): void
             throw new IllegalLinkException();
         }
 
-        /** @var IHistorySavingObjectTypeProvider $processor */
+        /** @var IHistorySavingObjectTypeProvider<DatabaseObject> $processor */
         $processor = $this->objectType->getProcessor();
 
         /** @var (DatabaseObject&IHistorySavingObject) $object */
diff --git a/wcfsetup/install/files/lib/page/FollowingPage.class.php b/wcfsetup/install/files/lib/page/FollowingPage.class.php
index 56f3c2281d1..6a6ea323156 100644
--- a/wcfsetup/install/files/lib/page/FollowingPage.class.php
+++ b/wcfsetup/install/files/lib/page/FollowingPage.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserFollowingList $objectList
+ * @extends MultipleLinkPage<UserFollowingList>
  */
 class FollowingPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/IPage.class.php b/wcfsetup/install/files/lib/page/IPage.class.php
index 4484f3b2027..a96eb9de5ed 100644
--- a/wcfsetup/install/files/lib/page/IPage.class.php
+++ b/wcfsetup/install/files/lib/page/IPage.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\page;
 
+use Psr\Http\Message\ResponseInterface;
+
 /**
  * All page classes should implement this interface.
  *
@@ -13,36 +15,50 @@ interface IPage
 {
     /**
      * Initializes the page.
+     *
+     * @return void|ResponseInterface
      */
     public function __run();
 
     /**
      * Reads the given parameters.
+     *
+     * @return void|ResponseInterface
      */
     public function readParameters();
 
     /**
      * Checks the modules of this page.
+     *
+     * @return void
      */
     public function checkModules();
 
     /**
      * Checks the permissions of this page.
+     *
+     * @return void
      */
     public function checkPermissions();
 
     /**
      * Reads/Gets the data to be displayed on this page.
+     *
+     * @return void|ResponseInterface
      */
     public function readData();
 
     /**
      * Assigns variables to the template engine.
+     *
+     * @return void
      */
     public function assignVariables();
 
     /**
      * Shows the requested page.
+     *
+     * @return void|ResponseInterface
      */
     public function show();
 }
diff --git a/wcfsetup/install/files/lib/page/IgnoredUsersPage.class.php b/wcfsetup/install/files/lib/page/IgnoredUsersPage.class.php
index 2ec3539cbba..3f187d80154 100644
--- a/wcfsetup/install/files/lib/page/IgnoredUsersPage.class.php
+++ b/wcfsetup/install/files/lib/page/IgnoredUsersPage.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ViewableUserIgnoreList $objectList
+ * @extends MultipleLinkPage<ViewableUserIgnoreList>
  */
 class IgnoredUsersPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/MembersListPage.class.php b/wcfsetup/install/files/lib/page/MembersListPage.class.php
index fe12421959c..39fcd721872 100644
--- a/wcfsetup/install/files/lib/page/MembersListPage.class.php
+++ b/wcfsetup/install/files/lib/page/MembersListPage.class.php
@@ -18,7 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserProfileList $objectList
+ * @extends SortablePage<UserProfileList>
  */
 class MembersListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/page/ModerationListPage.class.php b/wcfsetup/install/files/lib/page/ModerationListPage.class.php
index 659e94efcc4..d7d703cfe14 100644
--- a/wcfsetup/install/files/lib/page/ModerationListPage.class.php
+++ b/wcfsetup/install/files/lib/page/ModerationListPage.class.php
@@ -18,7 +18,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    ViewableModerationQueueList $objectList
+ * @extends SortablePage<ViewableModerationQueueList>
  */
 class ModerationListPage extends SortablePage
 {
diff --git a/wcfsetup/install/files/lib/page/MultipleLinkPage.class.php b/wcfsetup/install/files/lib/page/MultipleLinkPage.class.php
index 8502cb95962..868842e0961 100644
--- a/wcfsetup/install/files/lib/page/MultipleLinkPage.class.php
+++ b/wcfsetup/install/files/lib/page/MultipleLinkPage.class.php
@@ -15,6 +15,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 abstract class MultipleLinkPage extends AbstractPage
 {
@@ -55,8 +57,7 @@ abstract class MultipleLinkPage extends AbstractPage
     public $endIndex = 0;
 
     /**
-     * DatabaseObjectList object
-     * @var DatabaseObjectList
+     * @var TDatabaseObjectList
      */
     public $objectList;
 
@@ -144,6 +145,8 @@ public function readData()
 
     /**
      * Initializes DatabaseObjectList instance.
+     *
+     * @return void
      */
     protected function initObjectList()
     {
@@ -160,6 +163,8 @@ protected function initObjectList()
 
     /**
      * Reads object list.
+     *
+     * @return void
      */
     protected function readObjects()
     {
@@ -177,6 +182,8 @@ protected function readObjects()
     /**
      * Calculates the number of pages and
      * handles the given page number parameter.
+     *
+     * @return void
      */
     public function calculateNumberOfPages()
     {
@@ -207,7 +214,7 @@ public function calculateNumberOfPages()
     /**
      * Counts the displayed items.
      *
-     * @return  int
+     * @return int
      */
     public function countItems()
     {
@@ -220,7 +227,7 @@ public function countItems()
     /**
      * Returns true if current page is the first page.
      *
-     * @return  bool
+     * @return bool
      */
     public function isFirstPage()
     {
@@ -230,7 +237,7 @@ public function isFirstPage()
     /**
      * Returns true if current page is the last page.
      *
-     * @return  bool
+     * @return bool
      */
     public function isLastPage()
     {
diff --git a/wcfsetup/install/files/lib/page/NotificationListPage.class.php b/wcfsetup/install/files/lib/page/NotificationListPage.class.php
index e41bdabb2c3..4db784ad2d6 100644
--- a/wcfsetup/install/files/lib/page/NotificationListPage.class.php
+++ b/wcfsetup/install/files/lib/page/NotificationListPage.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\system\user\notification\UserNotificationHandler;
 use wcf\system\WCF;
 
@@ -11,6 +13,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends MultipleLinkPage<DatabaseObjectList<DatabaseObject>>
  */
 class NotificationListPage extends MultipleLinkPage
 {
@@ -36,16 +40,12 @@ public function countItems()
     /**
      * @inheritDoc
      */
-    protected function initObjectList()
-    {
-    }
+    protected function initObjectList() {}
 
     /**
      * @inheritDoc
      */
-    protected function readObjects()
-    {
-    }
+    protected function readObjects() {}
 
     /**
      * @inheritDoc
diff --git a/wcfsetup/install/files/lib/page/PaidSubscriptionListPage.class.php b/wcfsetup/install/files/lib/page/PaidSubscriptionListPage.class.php
index 6183e146c60..92860dde725 100644
--- a/wcfsetup/install/files/lib/page/PaidSubscriptionListPage.class.php
+++ b/wcfsetup/install/files/lib/page/PaidSubscriptionListPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\page;
 
+use wcf\data\paid\subscription\PaidSubscription;
 use wcf\data\paid\subscription\user\PaidSubscriptionUserList;
 use wcf\system\cache\builder\PaidSubscriptionCacheBuilder;
 use wcf\system\exception\PermissionDeniedException;
@@ -34,7 +35,7 @@ class PaidSubscriptionListPage extends AbstractPage
 
     /**
      * list of available paid subscriptions
-     * @var array
+     * @var array<int, PaidSubscription>
      */
     public $subscriptions = [];
 
diff --git a/wcfsetup/install/files/lib/page/SearchResultPage.class.php b/wcfsetup/install/files/lib/page/SearchResultPage.class.php
index 9a6340de451..d1abb98b968 100644
--- a/wcfsetup/install/files/lib/page/SearchResultPage.class.php
+++ b/wcfsetup/install/files/lib/page/SearchResultPage.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\search\ISearchResultObject;
 use wcf\data\search\Search;
 use wcf\system\event\EventHandler;
@@ -20,6 +22,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @deprecated 5.5
+ *
+ * @extends MultipleLinkPage<DatabaseObjectList<DatabaseObject>>
  */
 class SearchResultPage extends MultipleLinkPage
 {
@@ -48,13 +52,13 @@ class SearchResultPage extends MultipleLinkPage
 
     /**
      * messages
-     * @var array
+     * @var ISearchResultObject[]
      */
     public $messages = [];
 
     /**
      * search data
-     * @var array
+     * @var mixed[]
      */
     public $searchData;
 
@@ -98,6 +102,8 @@ public function readParameters()
     /**
      * Attempts to start a new search if the search id is invalid or unavailable, and the
      * highlight parameter is available.
+     *
+     * @return void
      */
     protected function redirectOrReject()
     {
@@ -137,6 +143,8 @@ public function readData()
 
     /**
      * Caches the message data.
+     *
+     * @return void
      */
     protected function cacheMessageData()
     {
@@ -161,6 +169,8 @@ protected function cacheMessageData()
 
     /**
      * Reads the data of the search result messages.
+     *
+     * @return void
      */
     protected function readMessages()
     {
@@ -193,16 +203,12 @@ public function countItems()
     /**
      * @inheritDoc
      */
-    protected function initObjectList()
-    {
-    }
+    protected function initObjectList() {}
 
     /**
      * @inheritDoc
      */
-    protected function readObjects()
-    {
-    }
+    protected function readObjects() {}
 
     /**
      * @inheritDoc
diff --git a/wcfsetup/install/files/lib/page/SortablePage.class.php b/wcfsetup/install/files/lib/page/SortablePage.class.php
index abc5f1a1229..eb35d102d07 100644
--- a/wcfsetup/install/files/lib/page/SortablePage.class.php
+++ b/wcfsetup/install/files/lib/page/SortablePage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObjectList;
 use wcf\system\event\EventHandler;
 use wcf\system\WCF;
 
@@ -12,6 +13,9 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
+ * @extends MultipleLinkPage<TDatabaseObjectList>
  */
 abstract class SortablePage extends MultipleLinkPage
 {
@@ -62,6 +66,8 @@ public function readData()
 
     /**
      * Validates the given sort field parameter.
+     *
+     * @return void
      */
     public function validateSortField()
     {
@@ -75,6 +81,8 @@ public function validateSortField()
 
     /**
      * Validates the given sort order parameter.
+     *
+     * @return void
      */
     public function validateSortOrder()
     {
diff --git a/wcfsetup/install/files/lib/page/TaggedPage.class.php b/wcfsetup/install/files/lib/page/TaggedPage.class.php
index 356ccceeaa2..6cc118f2cd5 100644
--- a/wcfsetup/install/files/lib/page/TaggedPage.class.php
+++ b/wcfsetup/install/files/lib/page/TaggedPage.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\page;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
@@ -17,6 +18,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends MultipleLinkPage<DatabaseObjectList<DatabaseObject>>
  */
 class TaggedPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/TeamPage.class.php b/wcfsetup/install/files/lib/page/TeamPage.class.php
index 7a0fc9653cd..6a952fb0b74 100644
--- a/wcfsetup/install/files/lib/page/TeamPage.class.php
+++ b/wcfsetup/install/files/lib/page/TeamPage.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    TeamList $objectList
+ * @extends MultipleLinkPage<TeamList>
  */
 class TeamPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/TrophyListPage.class.php b/wcfsetup/install/files/lib/page/TrophyListPage.class.php
index 2766ee382ad..580de3694f3 100644
--- a/wcfsetup/install/files/lib/page/TrophyListPage.class.php
+++ b/wcfsetup/install/files/lib/page/TrophyListPage.class.php
@@ -16,7 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    TrophyList $objectList
+ * @extends MultipleLinkPage<TrophyList>
  */
 class TrophyListPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/TrophyPage.class.php b/wcfsetup/install/files/lib/page/TrophyPage.class.php
index e361c9fdfc8..03ebe9e4188 100644
--- a/wcfsetup/install/files/lib/page/TrophyPage.class.php
+++ b/wcfsetup/install/files/lib/page/TrophyPage.class.php
@@ -27,7 +27,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @property    UserTrophyList $objectList
+ * @extends MultipleLinkPage<UserTrophyList>
  */
 class TrophyPage extends MultipleLinkPage
 {
diff --git a/wcfsetup/install/files/lib/page/UsersOnlineListPage.class.php b/wcfsetup/install/files/lib/page/UsersOnlineListPage.class.php
index e172de38445..60c84257e61 100644
--- a/wcfsetup/install/files/lib/page/UsersOnlineListPage.class.php
+++ b/wcfsetup/install/files/lib/page/UsersOnlineListPage.class.php
@@ -3,7 +3,6 @@
 namespace wcf\page;
 
 use wcf\data\page\PageCache;
-use wcf\data\user\online\UserOnline;
 use wcf\data\user\online\UsersOnlineList;
 use wcf\system\page\handler\IOnlineLocationPageHandler;
 use wcf\system\page\PageLocationManager;
@@ -18,7 +17,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UsersOnlineList $objectList
+ * @extends SortablePage<UsersOnlineList>
  */
 class UsersOnlineListPage extends SortablePage
 {
@@ -54,7 +53,7 @@ class UsersOnlineListPage extends SortablePage
 
     /**
      * page locations
-     * @var array
+     * @var mixed[]
      */
     public $locations = [];
 
@@ -120,14 +119,13 @@ public function readData()
         // cache all necessary data for showing locations
         foreach ($this->objectList as $userOnline) {
             $page = PageCache::getInstance()->getPage($userOnline->pageID);
-            if ($page !== null && $page->getHandler() !== null && $page->getHandler() instanceof IOnlineLocationPageHandler) {
-                /** @noinspection PhpUndefinedMethodInspection */
-                $page->getHandler()->prepareOnlineLocation($page, $userOnline);
+            $pageHandler = $page?->getHandler();
+            if ($pageHandler instanceof IOnlineLocationPageHandler) {
+                $pageHandler->prepareOnlineLocation($page, $userOnline);
             }
         }
 
         // set locations
-        /** @var UserOnline $userOnline */
         foreach ($this->objectList as $userOnline) {
             $userOnline->setLocation();
         }
diff --git a/wcfsetup/install/files/lib/system/CLIWCF.class.php b/wcfsetup/install/files/lib/system/CLIWCF.class.php
index 8a2b7048144..ed9d2896997 100644
--- a/wcfsetup/install/files/lib/system/CLIWCF.class.php
+++ b/wcfsetup/install/files/lib/system/CLIWCF.class.php
@@ -96,10 +96,7 @@ public static function destruct(): void
         }
     }
 
-    /**
-     * @inheritDoc
-     */
-    final public static function handleCLIException($e): never
+    final public static function handleCLIException(\Throwable $e): never
     {
         exit($e->getMessage() . "\n" . $e->getTraceAsString());
     }
diff --git a/wcfsetup/install/files/lib/system/MetaTagHandler.class.php b/wcfsetup/install/files/lib/system/MetaTagHandler.class.php
index 6c7eedf8da2..68eecb6b9bb 100644
--- a/wcfsetup/install/files/lib/system/MetaTagHandler.class.php
+++ b/wcfsetup/install/files/lib/system/MetaTagHandler.class.php
@@ -10,25 +10,27 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements \Iterator<string, string>
  */
 final class MetaTagHandler extends SingletonFactory implements \Countable, \Iterator
 {
     /**
      * current iterator index
      */
-    protected int $index = 0;
+    private int $index = 0;
 
     /**
      * list of index to object relation
-     * @var int[]
+     * @var list<string>
      */
-    protected $indexToObject = [];
+    private array $indexToObject = [];
 
     /**
      * list of meta tags
-     * @var array
+     * @var array<string, array{isProperty: bool, name: string, value: string}>
      */
-    protected $objects = [];
+    private array $objects = [];
 
     /**
      * @inheritDoc
@@ -112,7 +114,7 @@ public function current(): string
      *
      * @see \Iterator::key()
      */
-    public function key(): int
+    public function key(): string
     {
         return $this->indexToObject[$this->index];
     }
diff --git a/wcfsetup/install/files/lib/system/Regex.class.php b/wcfsetup/install/files/lib/system/Regex.class.php
index a745ef0726a..443706b2e80 100644
--- a/wcfsetup/install/files/lib/system/Regex.class.php
+++ b/wcfsetup/install/files/lib/system/Regex.class.php
@@ -111,23 +111,16 @@ final class Regex
 
     /**
      * compiled regex
-     * @var string
      */
-    private $regex = '';
+    private string $regex = '';
 
     /**
      * last matches
-     * @var array
+     * @var array<string|int, mixed|mixed[]>|array{}
      */
-    private $matches = [];
+    private array $matches = [];
 
-    /**
-     * Creates a regex.
-     *
-     * @param string $regex
-     * @param int $modifier
-     */
-    public function __construct($regex, $modifier = self::MODIFIER_NONE)
+    public function __construct(string $regex, int $modifier = self::MODIFIER_NONE)
     {
         // escape delimiter
         $regex = \str_replace(self::REGEX_DELIMITER, '\\' . self::REGEX_DELIMITER, $regex);
@@ -159,28 +152,20 @@ public function __construct($regex, $modifier = self::MODIFIER_NONE)
         }
     }
 
-    /**
-     * @inheritDoc
-     */
-    public static function compile($regex, $modifier = self::MODIFIER_NONE)
+    public static function compile(string $regex, int $modifier = self::MODIFIER_NONE): self
     {
         return new self($regex, $modifier);
     }
 
-    /**
-     * @inheritDoc
-     */
-    public function __invoke($string)
+    public function __invoke(string $string): int
     {
         return $this->match($string);
     }
 
     /**
      * Checks whether the regex is syntactically correct.
-     *
-     * @return  bool
      */
-    public function isValid()
+    public function isValid(): bool
     {
         try {
             $this->match(''); // we don't care about the result, we only care about the exception
@@ -192,17 +177,15 @@ public function isValid()
         }
     }
 
-    // @codingStandardsIgnoreStart
-
     /**
      * Checks whether the regex matches the given string.
      *
      * @param string $string string to match
      * @param bool $all indicates if all matches are collected
      * @param int $flags match flags
-     * @return    int                return value of preg_match(_all)
+     * @return int return value of preg_match(_all)
      */
-    public function match($string, $all = false, $flags = self::FLAGS_DEFAULT)
+    public function match(string $string, bool $all = false, int $flags = self::FLAGS_DEFAULT): int
     {
         $matchFlags = 0;
         if ($flags & self::CAPTURE_OFFSET) {
@@ -229,11 +212,9 @@ public function match($string, $all = false, $flags = self::FLAGS_DEFAULT)
     /**
      * Replaces part of the string with the regex.
      *
-     * @param string $string
      * @param mixed $replacement replacement-string or closure
-     * @return    string
      */
-    public function replace($string, $replacement)
+    public function replace(string $string, mixed $replacement): string
     {
         if ($replacement instanceof Callback || $replacement instanceof \Closure) {
             return $this->checkResult(\preg_replace_callback($this->regex, $replacement, $string), 'replace');
@@ -245,11 +226,9 @@ public function replace($string, $replacement)
     /**
      * Splits the string with the regex.
      *
-     * @param string $string
-     * @param int $flags
-     * @return    string[]
+     * @return string[]
      */
-    public function split($string, $flags = self::FLAGS_DEFAULT)
+    public function split(string $string, int $flags = self::FLAGS_DEFAULT): array
     {
         $splitFlags = 0;
         if ($flags & self::CAPTURE_OFFSET) {
@@ -265,17 +244,12 @@ public function split($string, $flags = self::FLAGS_DEFAULT)
         return $this->checkResult(\preg_split($this->regex, $string, -1, $splitFlags), 'split');
     }
 
-    // @codingStandardsIgnoreEnd
-
     /**
      * Checks whether there was success.
      *
-     * @param mixed $result
-     * @param string $method
-     * @return  mixed
-     * @throws  SystemException
+     * @throws SystemException
      */
-    private function checkResult($result, $method = '')
+    private function checkResult(mixed $result, string $method = ''): mixed
     {
         if ($result === false || $result === null) {
             switch (\preg_last_error()) {
@@ -309,19 +283,17 @@ private function checkResult($result, $method = '')
     /**
      * Returns the matches of the last string.
      *
-     * @return  array
+     * @return array<string|int, mixed|mixed[]>
      */
-    public function getMatches()
+    public function getMatches(): array
     {
         return $this->matches;
     }
 
     /**
      * Returns the compiled regex.
-     *
-     * @return  string
      */
-    public function getRegex()
+    public function getRegex(): string
     {
         return $this->regex;
     }
diff --git a/wcfsetup/install/files/lib/system/TemplateScriptingCore.class.php b/wcfsetup/install/files/lib/system/TemplateScriptingCore.class.php
index 796aac47911..7a633f151e8 100644
--- a/wcfsetup/install/files/lib/system/TemplateScriptingCore.class.php
+++ b/wcfsetup/install/files/lib/system/TemplateScriptingCore.class.php
@@ -34,8 +34,8 @@ public function __construct(WCF $wcf)
      * and the template object.
      *
      * @param string $name called method
-     * @param array $arguments method parameters
-     * @return  mixed
+     * @param mixed[] $arguments method parameters
+     * @return mixed
      */
     public function __call($name, array $arguments)
     {
diff --git a/wcfsetup/install/files/lib/system/WCF.class.php b/wcfsetup/install/files/lib/system/WCF.class.php
index 836a94a9984..a0baee82d54 100644
--- a/wcfsetup/install/files/lib/system/WCF.class.php
+++ b/wcfsetup/install/files/lib/system/WCF.class.php
@@ -126,7 +126,7 @@ class WCF
 
     /**
      * list of autoload directories
-     * @var array
+     * @var array<string, string>
      */
     protected static $autoloadDirectories = [
         'wcf' => WCF_DIR . 'lib/',
@@ -234,6 +234,8 @@ final protected function runBootstrappers(): void
      *
      * You *must* not create output in here under normal circumstances, as it might get eaten
      * when gzip is enabled.
+     *
+     * @return void
      */
     public static function destruct()
     {
@@ -325,7 +327,7 @@ final public static function getTPL()
     /**
      * Calls the show method on the given exception.
      */
-    final public static function handleException(\Throwable $e)
+    final public static function handleException(\Throwable $e): never
     {
         // backwards compatibility
         if ($e instanceof IPrintableException) {
@@ -345,6 +347,8 @@ final public static function handleException(\Throwable $e)
         @\header('HTTP/1.1 500 Internal Server Error');
         try {
             \wcf\functions\exception\printThrowable($e);
+
+            exit;
         } catch (\Throwable $e2) {
             echo "<pre>An Exception was thrown while handling an Exception:\n\n";
             echo \preg_replace('/Database->__construct\(.*\)/', 'Database->__construct(...)', $e2);
@@ -881,7 +885,8 @@ final public static function autoloadDebug(string $className): void
     }
 
     /**
-     * @inheritDoc
+     * @param mixed[] $arguments
+     * @return ?object
      */
     final public function __call(string $name, array $arguments)
     {
@@ -896,9 +901,9 @@ final public function __call(string $name, array $arguments)
     /**
      * Returns dynamically loaded core objects.
      *
-     * @param array $arguments
-     * @return  object|null
-     * @throws  SystemException
+     * @param mixed[] $arguments
+     * @return ?object
+     * @throws SystemException
      */
     final public static function __callStatic(string $name, array $arguments)
     {
@@ -998,6 +1003,7 @@ public static function getActivePath(): string
     }
 
     /**
+     * @param string $fragment
      * @deprecated 5.5 - Put a '#' followed by the fragment as the anchor's href. Make sure to |rawurlencode any variables that may contain special characters.
      */
     public function getAnchor($fragment): string
diff --git a/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php b/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
index 7304bd1bfe0..459e062758f 100644
--- a/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
+++ b/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
@@ -6,6 +6,7 @@
 use wcf\data\acl\option\ACLOptionList;
 use wcf\data\acl\option\category\ACLOptionCategory;
 use wcf\data\acl\option\category\ACLOptionCategoryList;
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\data\user\group\UserGroup;
 use wcf\data\user\User;
@@ -22,6 +23,11 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type Permissions array{
+ *  options: ACLOptionList,
+ *  group: array<int, array<int, array<int, int>>>,
+ *  user: array<int, array<int, array<int, int>>>,
+ * }
  */
 class ACLHandler extends SingletonFactory
 {
@@ -33,7 +39,7 @@ class ACLHandler extends SingletonFactory
 
     /**
      * list of available object types
-     * @var array
+     * @var array<string, ObjectType>
      */
     protected $availableObjectTypes = [];
 
@@ -45,9 +51,9 @@ class ACLHandler extends SingletonFactory
 
     /**
      * explicitly read acl values grouped by object type id
-     * @var     array
-     * @see     ACLHandler::readValues()
-     * @since   5.2
+     * @var mixed[]
+     * @see ACLHandler::readValues()
+     * @since 5.2
      */
     protected $__readValues = [];
 
@@ -55,6 +61,7 @@ class ACLHandler extends SingletonFactory
      * Assigns the acl values to the template.
      *
      * @param int $objectTypeID
+     * @return void
      */
     public function assignVariables($objectTypeID)
     {
@@ -116,6 +123,8 @@ public function assignVariables($objectTypeID)
 
     /**
      * Disables assignment of variables to template.
+     *
+     * @return void
      */
     public function disableAssignVariables()
     {
@@ -124,6 +133,8 @@ public function disableAssignVariables()
 
     /**
      * Enables assignment of variables to template.
+     *
+     * @return void
      */
     public function enableAssignVariables()
     {
@@ -137,8 +148,9 @@ public function enableAssignVariables()
      * using form builder, you do not need this method.
      *
      * @param int $objectTypeID
-     * @param array|null $valuesSource array used to read the values from (if `null`, `$_POST['aclValues']` is used)
-     * @since   5.2
+     * @param ?mixed[] $valuesSource array used to read the values from (if `null`, `$_POST['aclValues']` is used)
+     * @return void
+     * @since 5.2
      */
     public function readValues($objectTypeID, ?array $valuesSource = null)
     {
@@ -178,7 +190,8 @@ public function readValues($objectTypeID, ?array $valuesSource = null)
      * using form builder, you do not need this method.
      *
      * @param int $objectTypeID
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function resetValues($objectTypeID)
     {
@@ -198,8 +211,8 @@ protected function init()
      * Returns the id of the given acl object type.
      *
      * @param string $objectType
-     * @return  int
-     * @throws  SystemException
+     * @return int
+     * @throws SystemException
      */
     public function getObjectTypeID($objectType)
     {
@@ -216,7 +229,7 @@ public function getObjectTypeID($objectType)
      *
      * @param int $objectTypeID
      * @param string $categoryName
-     * @return  ACLOptionCategory|null
+     * @return ?ACLOptionCategory
      */
     public function getCategory($objectTypeID, $categoryName)
     {
@@ -228,6 +241,7 @@ public function getCategory($objectTypeID, $categoryName)
      *
      * @param int $objectID
      * @param int $objectTypeID
+     * @return void
      */
     public function save($objectID, $objectTypeID)
     {
@@ -244,6 +258,7 @@ public function save($objectID, $objectTypeID)
      * @param ACLOptionList $optionList
      * @param string $type
      * @param int $objectID
+     * @return void
      */
     protected function replaceValues(ACLOptionList $optionList, $type, $objectID)
     {
@@ -300,10 +315,10 @@ protected function replaceValues(ACLOptionList $optionList, $type, $objectID)
      * Returns a list of permissions by object type id.
      *
      * @param int $objectTypeID
-     * @param array $objectIDs
+     * @param int[] $objectIDs
      * @param ?string $categoryName
      * @param bool $settingsView
-     * @return  array
+     * @return mixed[]
      */
     public function getPermissions($objectTypeID, array $objectIDs, $categoryName = '', $settingsView = false)
     {
@@ -361,9 +376,11 @@ public function getPermissions($objectTypeID, array $objectIDs, $categoryName =
      *
      * @param ACLOptionList $optionList
      * @param string $type
-     * @param array $objectIDs
-     * @param array $data
+     * @param int[] $objectIDs
+     * @param mixed[] $data
      * @param bool $settingsView
+     * @param-out mixed[] $data
+     * @return void
      */
     protected function getValues(ACLOptionList $optionList, $type, array $objectIDs, array &$data, $settingsView)
     {
@@ -470,6 +487,7 @@ public function getOptions($objectTypeID, $categoryName = '')
      * @param int $objectTypeID
      * @param int[] $objectIDs
      * @param ACLOptionCategory $category
+     * @return void
      */
     public function removeValues($objectTypeID, array $objectIDs, ?ACLOptionCategory $category = null)
     {
diff --git a/wcfsetup/install/files/lib/system/acl/simple/SimpleAclHandler.class.php b/wcfsetup/install/files/lib/system/acl/simple/SimpleAclHandler.class.php
index 707c2b11a9a..96d1b2f52d3 100644
--- a/wcfsetup/install/files/lib/system/acl/simple/SimpleAclHandler.class.php
+++ b/wcfsetup/install/files/lib/system/acl/simple/SimpleAclHandler.class.php
@@ -56,7 +56,11 @@ public function getObjectTypeID($objectType)
      *
      * @param string $objectType object type name
      * @param int $objectID object id
-     * @return      array           array containing the keys `allowAll`, `user` and `group`
+     * @return array{
+     *  allowAll: bool,
+     *  user: (User|null)[],
+     *  group: UserGroup[],
+     * }
      */
     public function getValues($objectType, $objectID)
     {
@@ -110,8 +114,9 @@ public function getValues($objectType, $objectID)
      *
      * @param string $objectType object type name
      * @param int $objectID object id
-     * @param array $values list of user and group ids
-     * @throws  \InvalidArgumentException
+     * @param array{allowAll?: bool, user?: (User|null)[], group?: UserGroup[]} $values list of user and group ids
+     * @return void
+     * @throws \InvalidArgumentException
      */
     public function setValues($objectType, $objectID, array $values)
     {
@@ -190,8 +195,8 @@ public function setValues($objectType, $objectID, array $values)
      * Processes the provided values and returns the final
      * values for template assignment.
      *
-     * @param array $rawValues acl values as provided (by the user input)
-     * @return      array   final values for template assignment
+     * @param mixed[] $rawValues acl values as provided (by the user input)
+     * @return array{allowAll: bool, user: (User|null)[], group: UserGroup[]} final values for template assignment
      */
     public function getOutputValues(array $rawValues)
     {
diff --git a/wcfsetup/install/files/lib/system/acl/simple/SimpleAclResolver.class.php b/wcfsetup/install/files/lib/system/acl/simple/SimpleAclResolver.class.php
index 62fda95700f..ca55469a142 100644
--- a/wcfsetup/install/files/lib/system/acl/simple/SimpleAclResolver.class.php
+++ b/wcfsetup/install/files/lib/system/acl/simple/SimpleAclResolver.class.php
@@ -19,7 +19,7 @@ class SimpleAclResolver extends SingletonFactory
 {
     /**
      * cached permissions per object type
-     * @var array
+     * @var array<string, array<int, array{group: list<int>, user: list<int>}>>
      */
     protected $cache = [];
 
@@ -29,8 +29,8 @@ class SimpleAclResolver extends SingletonFactory
      *
      * @param string $objectType object type name
      * @param int $objectID object id
-     * @param User|null $user user object, if `null` uses current user
-     * @return      bool         false if user is not allowed
+     * @param ?User $user user object, if `null` uses current user
+     * @return bool false if user is not allowed
      */
     public function canAccess($objectType, $objectID, ?User $user = null)
     {
@@ -68,6 +68,7 @@ public function canAccess($objectType, $objectID, ?User $user = null)
      * Resets the cache for provided object type.
      *
      * @param string $objectType object type name
+     * @return void
      */
     public function resetCache($objectType)
     {
@@ -78,6 +79,7 @@ public function resetCache($objectType)
      * Attempts to load the cache for provided object type.
      *
      * @param string $objectType object type name
+     * @return void
      */
     protected function loadCache($objectType)
     {
diff --git a/wcfsetup/install/files/lib/system/acp/dashboard/AcpDashboard.class.php b/wcfsetup/install/files/lib/system/acp/dashboard/AcpDashboard.class.php
index f0a7df5655f..26b0f35e623 100644
--- a/wcfsetup/install/files/lib/system/acp/dashboard/AcpDashboard.class.php
+++ b/wcfsetup/install/files/lib/system/acp/dashboard/AcpDashboard.class.php
@@ -86,6 +86,14 @@ static function (IAcpDashboardBox $boxA, IAcpDashboardBox $boxB) use ($userConfi
         return $availableBoxes;
     }
 
+    /**
+     * @return array<string, array{
+     *  boxName: string,
+     *  userID: int,
+     *  enabled: int,
+     *  showOrder: int,
+     * }>
+     */
     public function getUserConfiguration(): array
     {
         $boxes = [];
diff --git a/wcfsetup/install/files/lib/system/acp/dashboard/box/ExpiringLicensesAcpDashboardBox.class.php b/wcfsetup/install/files/lib/system/acp/dashboard/box/ExpiringLicensesAcpDashboardBox.class.php
index 26bfec874ae..c6e6937c8c2 100644
--- a/wcfsetup/install/files/lib/system/acp/dashboard/box/ExpiringLicensesAcpDashboardBox.class.php
+++ b/wcfsetup/install/files/lib/system/acp/dashboard/box/ExpiringLicensesAcpDashboardBox.class.php
@@ -18,7 +18,12 @@
 final class ExpiringLicensesAcpDashboardBox extends AbstractAcpDashboardBox
 {
     private ?LicenseData $licenseData;
+
+    /**
+     * @var array<string, int>
+     */
     private array $expiredLicenses;
+
     private bool $fetchLicenseDataFailed = false;
 
     #[\Override]
@@ -33,6 +38,9 @@ public function hasContent(): bool
         return $this->getExpiredLicenses() !== [] || $this->fetchLicenseDataFailed;
     }
 
+    /**
+     * @return array<string, int>
+     */
     private function getExpiredLicenses(): array
     {
         if (!isset($this->expiredLicenses)) {
diff --git a/wcfsetup/install/files/lib/system/acp/dashboard/box/SystemInfoAcpDashboardBox.class.php b/wcfsetup/install/files/lib/system/acp/dashboard/box/SystemInfoAcpDashboardBox.class.php
index a971abbfe29..b08beb29cf0 100644
--- a/wcfsetup/install/files/lib/system/acp/dashboard/box/SystemInfoAcpDashboardBox.class.php
+++ b/wcfsetup/install/files/lib/system/acp/dashboard/box/SystemInfoAcpDashboardBox.class.php
@@ -11,6 +11,15 @@
  * @copyright   2001-2023 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
+ * @phpstan-type ServerInfo array{
+ *  os: string,
+ *  webserver: string,
+ *  mySQLVersion: string,
+ *  memoryLimit: string,
+ *  upload_max_filesize: string,
+ *  postMaxSize: string,
+ *  innodbFlushLogAtTrxCommit: int,
+ * }
  */
 final class SystemInfoAcpDashboardBox extends AbstractAcpDashboardBox
 {
@@ -32,6 +41,12 @@ public function getName(): string
         return 'com.woltlab.wcf.systemInfo';
     }
 
+    /**
+     * @return array{
+     *  databaseName: string,
+     *  server: ServerInfo,
+     * }
+     */
     private function getVariables(): array
     {
         return [
@@ -48,6 +63,9 @@ private function getDatabaseName(): string
         return $statement->fetchSingleColumn();
     }
 
+    /**
+     * @return ServerInfo
+     */
     private function getServerInfo(): array
     {
         return [
diff --git a/wcfsetup/install/files/lib/system/acp/dashboard/command/ConfigureBoxes.class.php b/wcfsetup/install/files/lib/system/acp/dashboard/command/ConfigureBoxes.class.php
index e4a1cef805d..f2737c73e81 100644
--- a/wcfsetup/install/files/lib/system/acp/dashboard/command/ConfigureBoxes.class.php
+++ b/wcfsetup/install/files/lib/system/acp/dashboard/command/ConfigureBoxes.class.php
@@ -16,6 +16,9 @@
  */
 final class ConfigureBoxes
 {
+    /**
+     * @param string[] $boxes
+     */
     public function __construct(
         private readonly AcpDashboard $dashboard,
         private readonly User $user,
@@ -23,7 +26,7 @@ public function __construct(
     ) {
     }
 
-    public function __invoke()
+    public function __invoke(): void
     {
         $this->resetBoxes();
         $this->saveBoxes();
diff --git a/wcfsetup/install/files/lib/system/application/AbstractApplication.class.php b/wcfsetup/install/files/lib/system/application/AbstractApplication.class.php
index 3e24b858a5e..d6698fe5d8c 100644
--- a/wcfsetup/install/files/lib/system/application/AbstractApplication.class.php
+++ b/wcfsetup/install/files/lib/system/application/AbstractApplication.class.php
@@ -35,6 +35,7 @@ abstract class AbstractApplication extends SingletonFactory implements IApplicat
     protected $evaluationPluginStoreID = 0;
 
     /**
+     * @var bool
      * @deprecated 5.5 - This value is unused and will always be 'false'. The 'active' status is determined live.
      */
     protected $isActiveApplication = false;
@@ -122,6 +123,7 @@ public function getPrimaryController()
     }
 
     /**
+     * @return void
      * @since 5.2
      * @deprecated 5.5 - This function is a noop. The 'active' status is determined live.
      */
diff --git a/wcfsetup/install/files/lib/system/application/IApplication.class.php b/wcfsetup/install/files/lib/system/application/IApplication.class.php
index 49cec3ca929..efd39218e73 100644
--- a/wcfsetup/install/files/lib/system/application/IApplication.class.php
+++ b/wcfsetup/install/files/lib/system/application/IApplication.class.php
@@ -15,13 +15,15 @@ interface IApplication
 {
     /**
      * Initializes this application, called after all applications have been loaded.
+     *
+     * @return void
      */
     public function __run();
 
     /**
      * Returns true if current application is treated as active and was invoked directly.
      *
-     * @return  bool
+     * @return bool
      */
     public function isActiveApplication();
 
@@ -29,7 +31,7 @@ public function isActiveApplication();
      * Returns the timestamp at which the evaluation period ends for this application. The
      * special value `0` indicates that there is no active evaluation period at this time.
      *
-     * @return      int
+     * @return int
      */
     public function getEvaluationEndDate();
 
@@ -37,18 +39,19 @@ public function getEvaluationEndDate();
      * Returns the id of the WoltLab Plugin-Store file where this app is for purchase. The
      * special value `0` indicates that there is no such file or it is a WoltLab app.
      *
-     * @return      int
+     * @return int
      */
     public function getEvaluationPluginStoreID();
 
     /**
      * Returns the qualified name of this application's primary controller.
      *
-     * @return  string
+     * @return string
      */
     public function getPrimaryController();
 
     /**
+     * @return SingletonFactory
      * @see SingletonFactory::getInstance()
      */
     public static function getInstance();
@@ -57,8 +60,8 @@ public static function getInstance();
      * Forwards unknown method calls to WCF.
      *
      * @param string $method
-     * @param array $arguments
-     * @return  mixed
+     * @param mixed[] $arguments
+     * @return mixed
      */
     public static function __callStatic($method, array $arguments);
 }
diff --git a/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php b/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
index 8aba13ce4ff..158d356ec93 100644
--- a/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
+++ b/wcfsetup/install/files/lib/system/article/discussion/IArticleDiscussionProvider.class.php
@@ -18,7 +18,7 @@ interface IArticleDiscussionProvider
     /**
      * Returns the number of discussion items.
      *
-     * @return      int
+     * @return int
      */
     public function getDiscussionCount();
 
@@ -26,28 +26,28 @@ public function getDiscussionCount();
      * Returns the simple phrase "X <discussions>" that is used for both the statistics
      * and the meta data in the article's headline.
      *
-     * @return      string
+     * @return string
      */
     public function getDiscussionCountPhrase();
 
     /**
      * Returns the permalink to the discussions or an empty string if there is none.
      *
-     * @return      string
+     * @return string
      */
     public function getDiscussionLink();
 
     /**
      * Renders the input and display section of the associated discussion.
      *
-     * @return      string
+     * @return string
      */
     public function renderDiscussions();
 
     /**
      * Sets the content object required for the separate discussions per article language.
      *
-     * @param ArticleContent $articleContent
+     * @return void
      */
     public function setArticleContent(ArticleContent $articleContent);
 
@@ -55,8 +55,7 @@ public function setArticleContent(ArticleContent $articleContent);
      * Returning true will assign this provider to the article, otherwise the next
      * possible provider is being evaluated.
      *
-     * @param Article $article
-     * @return      bool
+     * @return bool
      */
     public static function isResponsible(Article $article);
 }
diff --git a/wcfsetup/install/files/lib/system/attachment/AbstractAttachmentObjectType.class.php b/wcfsetup/install/files/lib/system/attachment/AbstractAttachmentObjectType.class.php
index 9174592d4e4..a63fa03d612 100644
--- a/wcfsetup/install/files/lib/system/attachment/AbstractAttachmentObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/AbstractAttachmentObjectType.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\attachment;
 
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\IUserContent;
 use wcf\system\WCF;
 use wcf\util\ArrayUtil;
@@ -12,12 +13,14 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @template T of object
+ * @implements IAttachmentObjectType<T>
  */
 abstract class AbstractAttachmentObjectType implements IAttachmentObjectType
 {
     /**
      * cached objects
-     * @var IUserContent[]
+     * @var array<int, ?T>
      */
     protected $cachedObjects = [];
 
@@ -62,7 +65,8 @@ public function getObject($objectID)
     }
 
     /**
-     * @inheritDoc
+     * @param array<int, ?T> $objects
+     * @return void
      */
     public function setCachedObjects(array $objects)
     {
diff --git a/wcfsetup/install/files/lib/system/attachment/ArticleAttachmentObjectType.class.php b/wcfsetup/install/files/lib/system/attachment/ArticleAttachmentObjectType.class.php
index dc981ff3eeb..48714bb2767 100644
--- a/wcfsetup/install/files/lib/system/attachment/ArticleAttachmentObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/ArticleAttachmentObjectType.class.php
@@ -14,7 +14,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.0
  *
- * @method      Article     getObject($objectID)
+ * @extends AbstractAttachmentObjectType<Article>
  */
 class ArticleAttachmentObjectType extends AbstractAttachmentObjectType
 {
diff --git a/wcfsetup/install/files/lib/system/attachment/AttachmentHandler.class.php b/wcfsetup/install/files/lib/system/attachment/AttachmentHandler.class.php
index 0d251ba2c09..9b1bf6755f2 100644
--- a/wcfsetup/install/files/lib/system/attachment/AttachmentHandler.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/AttachmentHandler.class.php
@@ -30,6 +30,7 @@ class AttachmentHandler implements \Countable
     /**
      * object type
      * @var IAttachmentObjectType
+     * @phpstan-ignore missingType.generics
      */
     protected $processor;
 
@@ -60,13 +61,11 @@ class AttachmentHandler implements \Countable
     private AttachmentFileProcessor $fileProcessor;
 
     /**
-     * Creates a new AttachmentHandler object.
-     *
      * @param string $objectType
      * @param int $objectID
      * @param string $tmpHash
      * @param int $parentObjectID
-     * @throws  SystemException
+     * @throws SystemException
      */
     public function __construct($objectType, $objectID, $tmpHash = '', $parentObjectID = 0)
     {
@@ -92,7 +91,7 @@ public function __construct($objectType, $objectID, $tmpHash = '', $parentObject
     /**
      * Returns a list of attachments.
      *
-     * @return  AttachmentList
+     * @return AttachmentList
      */
     public function getAttachmentList()
     {
@@ -123,6 +122,7 @@ public function count(): int
      * Sets the object id of temporary saved attachments.
      *
      * @param int $objectID
+     * @return void
      */
     public function updateObjectID($objectID)
     {
@@ -149,6 +149,7 @@ public function updateObjectID($objectID)
      * @param string $objectType
      * @param int $newObjectID
      * @param int[] $oldObjectIDs
+     * @return void
      */
     public static function transferAttachments($objectType, $newObjectID, array $oldObjectIDs)
     {
@@ -175,6 +176,7 @@ public static function transferAttachments($objectType, $newObjectID, array $old
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public static function removeAttachments($objectType, array $objectIDs)
     {
@@ -195,7 +197,7 @@ public static function removeAttachments($objectType, array $objectIDs)
     }
 
     /**
-     * @inheritDoc
+     * @return int
      */
     public function getMaxSize()
     {
@@ -203,7 +205,7 @@ public function getMaxSize()
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     public function getAllowedExtensions()
     {
@@ -229,7 +231,7 @@ public function getAllowedExtensions()
     /**
      * Returns a formatted list of the allowed file extensions.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getFormattedAllowedExtensions()
     {
@@ -259,7 +261,7 @@ public function getFormattedAllowedExtensions()
     }
 
     /**
-     * @inheritDoc
+     * @return int
      */
     public function getMaxCount()
     {
@@ -269,7 +271,7 @@ public function getMaxCount()
     /**
      * Returns true if the active user has the permission to upload attachments.
      *
-     * @return  bool
+     * @return bool
      */
     public function canUpload()
     {
@@ -279,7 +281,8 @@ public function canUpload()
     /**
      * Returns the object type processor.
      *
-     * @return  IAttachmentObjectType
+     * @return IAttachmentObjectType
+     * @phpstan-ignore missingType.generics
      */
     public function getProcessor()
     {
@@ -289,8 +292,8 @@ public function getProcessor()
     /**
      * Returns the temporary hashes used to identify the relevant uploaded attachments.
      *
-     * @return  string[]
-     * @since   5.2
+     * @return string[]
+     * @since 5.2
      */
     public function getTmpHashes()
     {
@@ -301,7 +304,8 @@ public function getTmpHashes()
      * Sets the temporary hashes used to identify the relevant uploaded attachments.
      *
      * @param string[] $tmpHash
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function setTmpHashes(array $tmpHash)
     {
@@ -311,8 +315,8 @@ public function setTmpHashes(array $tmpHash)
     /**
      * Returns the attachment object type
      *
-     * @return  ObjectType
-     * @since   5.2
+     * @return ObjectType
+     * @since 5.2
      */
     public function getObjectType()
     {
@@ -323,8 +327,8 @@ public function getObjectType()
      * Returns the id of the object the handled attachments belong to. If the object does not
      * exist (yet), `0` is returned.
      *
-     * @return  int
-     * @since   5.2
+     * @return int
+     * @since 5.2
      */
     public function getObjectID()
     {
@@ -335,8 +339,8 @@ public function getObjectID()
      * Returns the id of the parent object of the object the handled attachments belong to.
      * If no such parent object exists, `0` is returned.
      *
-     * @return  int
-     * @since   5.2
+     * @return int
+     * @since 5.2
      */
     public function getParentObjectID()
     {
diff --git a/wcfsetup/install/files/lib/system/attachment/ContactAttachmentObjectType.class.php b/wcfsetup/install/files/lib/system/attachment/ContactAttachmentObjectType.class.php
index 64508355981..67e047c5e35 100644
--- a/wcfsetup/install/files/lib/system/attachment/ContactAttachmentObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/ContactAttachmentObjectType.class.php
@@ -15,7 +15,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method ContactAttachment getObject($objectID)
+ * @extends AbstractAttachmentObjectType<ContactAttachment>
  */
 class ContactAttachmentObjectType extends AbstractAttachmentObjectType
 {
diff --git a/wcfsetup/install/files/lib/system/attachment/IAttachmentObjectType.class.php b/wcfsetup/install/files/lib/system/attachment/IAttachmentObjectType.class.php
index 3fcfec06fc2..93f309cf78d 100644
--- a/wcfsetup/install/files/lib/system/attachment/IAttachmentObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/IAttachmentObjectType.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\attachment;
 
 use wcf\data\attachment\Attachment;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\IUserContent;
 
 /**
@@ -11,6 +12,7 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @template T of object
  */
 interface IAttachmentObjectType
 {
@@ -18,7 +20,7 @@ interface IAttachmentObjectType
      * Returns true if the active user has the permission to download attachments.
      *
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function canDownload($objectID);
 
@@ -27,7 +29,7 @@ public function canDownload($objectID);
      * previews (thumbnails).
      *
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function canViewPreview($objectID);
 
@@ -36,7 +38,7 @@ public function canViewPreview($objectID);
      *
      * @param int $objectID
      * @param int $parentObjectID
-     * @return  bool
+     * @return bool
      */
     public function canUpload($objectID, $parentObjectID = 0);
 
@@ -44,28 +46,28 @@ public function canUpload($objectID, $parentObjectID = 0);
      * Returns true if the active user has the permission to delete attachments.
      *
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function canDelete($objectID);
 
     /**
      * Returns the maximum filesize for an attachment.
      *
-     * @return  int
+     * @return int
      */
     public function getMaxSize();
 
     /**
      * Returns the allowed file extensions.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getAllowedExtensions();
 
     /**
      * Returns the maximum number of attachments.
      *
-     * @return  int
+     * @return int
      */
     public function getMaxCount();
 
@@ -73,7 +75,7 @@ public function getMaxCount();
      * Returns the container object of an attachment or `null` if the container object does not exist.
      *
      * @param int $objectID
-     * @return  ?IUserContent
+     * @return ?T
      */
     public function getObject($objectID);
 
@@ -81,6 +83,7 @@ public function getObject($objectID);
      * Caches the data of the given container objects.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function cacheObjects(array $objectIDs);
 
@@ -88,6 +91,7 @@ public function cacheObjects(array $objectIDs);
      * Loads the permissions for given attachments.
      *
      * @param Attachment[] $attachments
+     * @return void
      */
     public function setPermissions(array $attachments);
 }
diff --git a/wcfsetup/install/files/lib/system/attachment/SignatureAttachmentObjectType.class.php b/wcfsetup/install/files/lib/system/attachment/SignatureAttachmentObjectType.class.php
index dee2805807b..21758f582d8 100644
--- a/wcfsetup/install/files/lib/system/attachment/SignatureAttachmentObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/attachment/SignatureAttachmentObjectType.class.php
@@ -16,7 +16,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method  UserProfile|null getObject($objectID)
+ * @extends AbstractAttachmentObjectType<UserProfile>
  */
 class SignatureAttachmentObjectType extends AbstractAttachmentObjectType
 {
diff --git a/wcfsetup/install/files/lib/system/background/job/AbstractBackgroundJob.class.php b/wcfsetup/install/files/lib/system/background/job/AbstractBackgroundJob.class.php
index 81bdd109bb4..d796d6b9e7f 100644
--- a/wcfsetup/install/files/lib/system/background/job/AbstractBackgroundJob.class.php
+++ b/wcfsetup/install/files/lib/system/background/job/AbstractBackgroundJob.class.php
@@ -23,14 +23,13 @@ abstract class AbstractBackgroundJob
 
     /**
      * The number of times this job already failed.
-     * @var int
      */
-    private $failures = 0;
+    private int $failures = 0;
 
     /**
      * Returns the number of times this job already failed.
      *
-     * @return  int
+     * @return int
      */
     final public function getFailures()
     {
@@ -40,7 +39,7 @@ final public function getFailures()
     /**
      * Increments the fail counter.
      */
-    final public function fail()
+    final public function fail(): void
     {
         $this->failures++;
 
@@ -50,7 +49,7 @@ final public function fail()
     /**
      * Returns the number of seconds to wait before requeuing a failed job.
      *
-     * @return  int 30 minutes by default
+     * @return int 30 minutes by default
      */
     public function retryAfter()
     {
@@ -61,6 +60,8 @@ public function retryAfter()
      * Performs the job. It will automatically be requeued up to MAX_FAILURES times
      * if it fails (either throws an Exception or does not finish until the clean up
      * cronjob comes along).
+     *
+     * @return void
      */
     abstract public function perform();
 
@@ -70,6 +71,7 @@ abstract public function perform();
      * Note: This method MUST NOT throw any exceptions. Doing so will lead to this job immediately
      * being failed completely.
      *
+     * @return void
      * @see AbstractBackgroundJob::fail()
      */
     public function onFailure()
@@ -86,6 +88,7 @@ public function onFailure()
      *
      * Note: Both onFailure() and onFinalFailure() will be called on the final failure.
      *
+     * @return void
      * @see AbstractBackgroundJob::onFailure()
      */
     public function onFinalFailure()
diff --git a/wcfsetup/install/files/lib/system/background/job/UnfurlUrlBackgroundJob.class.php b/wcfsetup/install/files/lib/system/background/job/UnfurlUrlBackgroundJob.class.php
index efc43d7b784..cac22bdd4e5 100644
--- a/wcfsetup/install/files/lib/system/background/job/UnfurlUrlBackgroundJob.class.php
+++ b/wcfsetup/install/files/lib/system/background/job/UnfurlUrlBackgroundJob.class.php
@@ -130,6 +130,16 @@ public function perform()
         }
     }
 
+    /**
+     * @return array{
+     *  imageUrl: string,
+     *  imageUrlHash: string,
+     *  fileID: ?int,
+     *  isStored: 1|0,
+     *  width: int,
+     *  height: int,
+     * }|array{}
+     */
     private function getImageData(UnfurlResponse $unfurlResponse): array
     {
         if (empty($unfurlResponse->getImageUrl()) || !Url::is($unfurlResponse->getImageUrl())) {
@@ -202,6 +212,9 @@ private function downloadImage(ResponseInterface $imageResponse): string
         return $image;
     }
 
+    /**
+     * @param array{0: int, 1: int, 2: int, 3: string, bits: int, channels: int, mime: string} $imageData
+     */
     private function validateImage(array $imageData): bool
     {
         $isSquared = $imageData[0] === $imageData[1];
@@ -219,6 +232,9 @@ private function validateImage(array $imageData): bool
         return true;
     }
 
+    /**
+     * @param array{0: int, 1: int, 2: int, 3: string, bits: int, channels: int, mime: string} $imageData
+     */
     private function createFile(array $imageData, string $originalFile, string $image): ?File
     {
         $extension = $this->getImageExtension($imageData);
@@ -240,6 +256,9 @@ private function createFile(array $imageData, string $originalFile, string $imag
         return $file;
     }
 
+    /**
+     * @param array{0: int, 1: int, 2: int, 3: string, bits: int, channels: int, mime: string} $imageData
+     */
     private function getImageExtension(array $imageData): ?string
     {
         $extension = ImageUtil::getExtensionByMimeType($imageData['mime']);
@@ -255,6 +274,9 @@ private function getImageExtension(array $imageData): ?string
         }
     }
 
+    /**
+     * @param array{imageUrl: string, imageUrlHash: string, fileID: ?int, isStored: 1|0, width: int, height: int}|array{} $imageData
+     */
     private function save(
         string $status,
         string $title = "",
diff --git a/wcfsetup/install/files/lib/system/bbcode/AbstractBBCode.class.php b/wcfsetup/install/files/lib/system/bbcode/AbstractBBCode.class.php
index d47d52f66f8..30ca4dca171 100644
--- a/wcfsetup/install/files/lib/system/bbcode/AbstractBBCode.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/AbstractBBCode.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  BBCode  getDecoratedObject()
  * @mixin   BBCode
+ * @extends DatabaseObjectDecorator<BBCode>
  */
 abstract class AbstractBBCode extends DatabaseObjectDecorator implements IBBCode
 {
diff --git a/wcfsetup/install/files/lib/system/bbcode/AttachmentBBCode.class.php b/wcfsetup/install/files/lib/system/bbcode/AttachmentBBCode.class.php
index b9878698a7b..47aa0057b0a 100644
--- a/wcfsetup/install/files/lib/system/bbcode/AttachmentBBCode.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/AttachmentBBCode.class.php
@@ -61,6 +61,9 @@ public function getParsedTag(array $openingTag, $content, array $closingTag, BBC
         return StringUtil::getAnchorTag($attachment->getLink(), $attachment->filename);
     }
 
+    /**
+     * @param list<string> $attributes
+     */
     private function showImage(Attachment $attachment, string $outputType, array $attributes, bool $hasParentLink): string
     {
         $alignment = $attributes[1] ?? '';
diff --git a/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php b/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
index 227528c4e25..bfa36ee8b30 100644
--- a/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
@@ -135,6 +135,7 @@ public function getButtonBBCodes($excludeCoreBBCodes = false)
      * Sets the disallowed BBCodes.
      *
      * @param string[] $bbCodes
+     * @return void
      */
     public function setDisallowedBBCodes(array $bbCodes)
     {
diff --git a/wcfsetup/install/files/lib/system/bbcode/BBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/BBCodeParser.class.php
index cf8af0913e2..95aa610cb77 100644
--- a/wcfsetup/install/files/lib/system/bbcode/BBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/BBCodeParser.class.php
@@ -13,12 +13,18 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type BBCodeTag array{
+ *  name: string,
+ *  closing: bool,
+ *  source: string,
+ *  attributes?: list<string>,
+ * }
  */
 class BBCodeParser extends SingletonFactory
 {
     /**
      * list of bbcodes
-     * @var BBCode[]
+     * @var array<string, BBCode>
      */
     protected $bbcodes = [];
 
@@ -41,14 +47,12 @@ class BBCodeParser extends SingletonFactory
     protected $parsedText = '';
 
     /**
-     * tag array
-     * @var array
+     * @var list<BBCodeTag>
      */
     protected $tagArray = [];
 
     /**
-     * text array
-     * @var array
+     * @var array<int, string>
      */
     protected $textArray = [];
 
@@ -82,6 +86,7 @@ protected function init()
      * Sets the output type of the parser.
      *
      * @param string $outputType
+     * @return void
      */
     public function setOutputType($outputType)
     {
@@ -91,7 +96,7 @@ public function setOutputType($outputType)
     /**
      * Returns the current output type.
      *
-     * @return  string
+     * @return string
      */
     public function getOutputType()
     {
@@ -102,6 +107,7 @@ public function getOutputType()
      * Sets the text to be parsed.
      *
      * @param string $text
+     * @return void
      */
     public function setText($text)
     {
@@ -112,7 +118,7 @@ public function setText($text)
      * Parses the given text.
      *
      * @param string $text
-     * @return  string      parsed text
+     * @return string parsed text
      */
     public function parse($text)
     {
@@ -127,6 +133,8 @@ public function parse($text)
     /**
      * Builds a valid xml structure of bbcode tags.
      * Inserts unclosed tags automatically.
+     *
+     * @return void
      */
     public function buildXMLStructure()
     {
@@ -231,8 +239,8 @@ public function buildXMLStructure()
     /**
      * Validates the attributes of a tag.
      *
-     * @param array $tag
-     * @return  bool
+     * @param BBCodeTag $tag
+     * @return bool
      */
     public function isValidTag(array $tag)
     {
@@ -277,9 +285,9 @@ public function isValidTag(array $tag)
     /**
      * Validates an attributes of a tag.
      *
-     * @param array $tagAttributes
+     * @param list<string> $tagAttributes
      * @param BBCodeAttribute $definedTagAttribute
-     * @return  bool
+     * @return bool
      */
     protected function isValidTagAttribute(array $tagAttributes, BBCodeAttribute $definedTagAttribute)
     {
@@ -305,8 +313,8 @@ protected function isValidTagAttribute(array $tagAttributes, BBCodeAttribute $de
     /**
      * Returns true if the text inside the given text needs to be buffered.
      *
-     * @param array $tag
-     * @return  bool
+     * @param BBCodeTag $tag
+     * @return bool
      */
     protected function needBuffering(array $tag)
     {
@@ -328,8 +336,8 @@ protected function needBuffering(array $tag)
     /**
      * Builds the opening tag.
      *
-     * @param array $tag
-     * @return  string
+     * @param BBCodeTag $tag
+     * @return string
      */
     protected function buildOpeningTag(array $tag)
     {
@@ -359,8 +367,8 @@ protected function buildOpeningTag(array $tag)
     /**
      * Builds the closing tag.
      *
-     * @param array $tag
-     * @return  string
+     * @param BBCodeTag $tag
+     * @return string
      */
     protected function buildClosingTag(array $tag)
     {
@@ -374,10 +382,10 @@ protected function buildClosingTag(array $tag)
     /**
      * Returns true if the given tag is allowed in the given list of open tags.
      *
-     * @param array $openTags
+     * @param mixed[] $openTags
      * @param string $tag
      * @param bool $closing
-     * @return  bool
+     * @return bool
      * @deprecated 5.5 This method is useless since 3.0, do not use it.
      */
     protected function isAllowed(array $openTags, $tag, $closing = false)
@@ -388,6 +396,8 @@ protected function isAllowed(array $openTags, $tag, $closing = false)
 
     /**
      * Builds the parsed string.
+     *
+     * @return void
      */
     public function buildParsedString()
     {
@@ -482,6 +492,7 @@ public function buildParsedString()
      * Builds the tag array from the given text.
      *
      * @param bool $ignoreSourceCodes
+     * @return void
      */
     public function buildTagArray($ignoreSourceCodes = true)
     {
@@ -508,6 +519,7 @@ public function buildTagArray($ignoreSourceCodes = true)
 
         // get bbcode tags
         \preg_match_all($pattern, $this->text, $matches);
+        // @phpstan-ignore assign.propertyType
         $this->tagArray = $matches[0];
         unset($matches);
 
@@ -524,7 +536,7 @@ public function buildTagArray($ignoreSourceCodes = true)
      * Builds a bbcode tag.
      *
      * @param string $string
-     * @return  array       bbcode tag data
+     * @return BBCodeTag
      */
     protected function buildTag($string)
     {
@@ -553,7 +565,7 @@ protected function buildTag($string)
      * Builds the attributes of a bbcode tag.
      *
      * @param string $string
-     * @return  array       bbcode attributes
+     * @return list<string> bbcode attributes
      */
     public function buildTagAttributes($string)
     {
@@ -576,7 +588,7 @@ public function buildTagAttributes($string)
      * Removes code bbcode occurrences in given message.
      *
      * @param string $message
-     * @return  string
+     * @return string
      */
     public function removeCodeTags($message)
     {
@@ -596,7 +608,7 @@ public function removeCodeTags($message)
     /**
      * Returns the list of bbcodes that represent block elements.
      *
-     * @return  string[]    list of bbcode block elements
+     * @return string[] list of bbcode block elements
      */
     public function getBlockBBCodes(): array
     {
@@ -618,7 +630,7 @@ public function getBlockBBCodes(): array
     /**
      * Returns the list of bbcodes that represent source code elements.
      *
-     * @return  string[]    list of bbcode source code elements
+     * @return list<string> list of bbcode source code elements
      */
     public function getSourceBBCodes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
index b8b4893dc37..616e6c78b9e 100644
--- a/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
@@ -235,6 +235,7 @@ private function createMetacodeMarker(string $bbcodeTag): ?\DOMElement
         if ($isClosingTag) {
             $this->closingTags[] = $metacodeMarker;
         } else {
+            // @phpstan-ignore argument.type
             if (!HtmlBBCodeParser::getInstance()->isValidTag(['name' => $name, 'attributes' => $attributes])) {
                 return null;
             }
diff --git a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
index ae94f71c17d..c49a58c4b0e 100644
--- a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
@@ -22,6 +22,14 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  * @deprecated 6.1 use `DomBBCodeParser` instead
+ *
+ * @phpstan-type BBCodeTag array{
+ *  name: string,
+ *  closing: bool,
+ *  source: string,
+ *  attributes?: list<string>,
+ *  useText?: int,
+ * }
  */
 class HtmlBBCodeParser extends BBCodeParser
 {
@@ -54,7 +62,7 @@ class HtmlBBCodeParser extends BBCodeParser
 
     /**
      * list of open tags with name and uuid
-     * @var array
+     * @var list<array{name: string, uuid: string}>
      */
     protected $openTagIdentifiers = [];
 
@@ -105,6 +113,8 @@ static function ($matches) use (&$codeBlocks) {
      * Reverts tags to their source representation if they either
      * have no matching counter part (such as opening tags without
      * closing one), or if they're inside code bbcodes.
+     *
+     * @return void
      */
     protected function ignoreUnclosedTags()
     {
@@ -155,11 +165,13 @@ protected function ignoreUnclosedTags()
 
         // step 2) check if tags are properly opened and closed, incorrect nesting doesn't matter here
         foreach ($this->tagArray as $i => &$tag) {
+            // @phpstan-ignore offsetAccess.notFound
             if (!$tag['valid']) {
                 continue;
             }
 
             if ($tag['closing']) {
+                // @phpstan-ignore isset.offset
                 if (!isset($tag['matching'])) {
                     $tag['valid'] = false;
                 }
@@ -202,6 +214,7 @@ protected function ignoreUnclosedTags()
         $newTagArray = $newTextArray = [];
         $buffer = '';
         foreach ($this->tagArray as $i => $tag) {
+            // @phpstan-ignore if.alwaysFalse
             if ($tag['valid']) {
                 // cleanup
                 unset($tag['matching']);
@@ -316,9 +329,9 @@ public function buildParsedString()
      * Builds the bbcode output.
      *
      * @param string $name bbcode identifier
-     * @param array $attributes list of attributes
+     * @param list<string> $attributes list of attributes
      * @param \DOMElement $element element
-     * @return  string      parsed bbcode
+     * @return string parsed bbcode
      */
     public function getHtmlOutput($name, array $attributes, \DOMElement $element)
     {
@@ -337,6 +350,7 @@ public function getHtmlOutput($name, array $attributes, \DOMElement $element)
 
                 return $processor->getParsedTag($openingTag, '<!-- META_CODE_INNER_CONTENT -->', $closingTag, $this);
             } else {
+                // @phpstan-ignore argument.type, argument.type
                 return parent::buildOpeningTag($openingTag) . '<!-- META_CODE_INNER_CONTENT -->' . parent::buildClosingTag($closingTag);
             }
         }
@@ -349,9 +363,9 @@ public function getHtmlOutput($name, array $attributes, \DOMElement $element)
      * Builds a plain bbcode string, used for unknown bbcodes.
      *
      * @param string $name bbcode identifier
-     * @param array $attributes list of attributes
+     * @param array<int, ?string> $attributes list of attributes
      * @param bool $openingTagOnly only render the opening tag
-     * @return  string
+     * @return string
      */
     public function buildBBCodeTag($name, $attributes, $openingTagOnly = false)
     {
@@ -381,10 +395,10 @@ public function buildBBCodeTag($name, $attributes, $openingTagOnly = false)
     /**
      * Compiles tag fragments into the custom HTML element.
      *
-     * @param array $openingTag opening tag data
+     * @param BBCodeTag $openingTag opening tag data
      * @param string $content content between opening and closing tag
-     * @param array $closingTag closing tag data
-     * @return  string  custom HTML element
+     * @param BBCodeTag $closingTag closing tag data
+     * @return string custom HTML element
      */
     protected function compileTag(array $openingTag, $content, array $closingTag)
     {
@@ -393,6 +407,7 @@ protected function compileTag(array $openingTag, $content, array $closingTag)
 
     /**
      * @inheritDoc
+     * @param BBCodeTag $tag
      */
     protected function buildOpeningTag(array $tag)
     {
@@ -401,7 +416,7 @@ protected function buildOpeningTag(array $tag)
             return $tag['source'];
         }
 
-        $index = (isset($tag['bufferPlaceholder'])) ? $tag['bufferPlaceholder'] : \count($this->openTagIdentifiers);
+        $index = \count($this->openTagIdentifiers);
 
         $uuid = StringUtil::getUUID();
         $this->openTagIdentifiers[$index] = [
diff --git a/wcfsetup/install/files/lib/system/bbcode/IBBCode.class.php b/wcfsetup/install/files/lib/system/bbcode/IBBCode.class.php
index 27e00b93c6f..46654f774bf 100644
--- a/wcfsetup/install/files/lib/system/bbcode/IBBCode.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/IBBCode.class.php
@@ -16,7 +16,9 @@ interface IBBCode extends IDatabaseObjectProcessor
     /**
      * Returns the parsed bbcode tag.
      *
+     * @param array{attributes: list<string>, name: string} $openingTag
      * @param string $content
+     * @param array{name: string, __parents: list<\DOMElement>} $closingTag
      */
     public function getParsedTag(array $openingTag, $content, array $closingTag, BBCodeParser $parser): string;
 }
diff --git a/wcfsetup/install/files/lib/system/bbcode/KeywordHighlighter.class.php b/wcfsetup/install/files/lib/system/bbcode/KeywordHighlighter.class.php
index bbb866d1f14..6e2bbdabc61 100644
--- a/wcfsetup/install/files/lib/system/bbcode/KeywordHighlighter.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/KeywordHighlighter.class.php
@@ -95,6 +95,7 @@ protected function init()
      * Parses search keywords.
      *
      * @param string $keywordString
+     * @return void
      */
     protected function parseKeywords($keywordString)
     {
diff --git a/wcfsetup/install/files/lib/system/bbcode/MessageParser.class.php b/wcfsetup/install/files/lib/system/bbcode/MessageParser.class.php
index 4390f8a0670..b5cc8f2764c 100644
--- a/wcfsetup/install/files/lib/system/bbcode/MessageParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/MessageParser.class.php
@@ -15,6 +15,14 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @deprecated  5.2 Use the HTML based message processing instead.
+ *
+ * @phpstan-type BBCodeTagWithContent array{
+ *  name: string,
+ *  closing: bool,
+ *  source: string,
+ *  attributes?: list<string>,
+ *  content: string,
+ * }
  */
 class MessageParser extends BBCodeParser
 {
@@ -26,7 +34,7 @@ class MessageParser extends BBCodeParser
 
     /**
      * cached bbcodes
-     * @var array
+     * @var array<string, BBCodeTagWithContent>
      */
     protected $cachedCodes = [];
 
@@ -71,7 +79,7 @@ protected function init()
      * @param bool $enableHtml
      * @param bool $enableBBCodes
      * @param bool $doKeywordHighlighting
-     * @return  string      parsed message
+     * @return string parsed message
      */
     public function parse(
         $text,
@@ -141,7 +149,7 @@ public function parse(
      *
      * @param string $text
      * @param bool $enableHtml
-     * @return  string
+     * @return string
      */
     protected function parseSmilies($text, $enableHtml = false)
     {
@@ -160,7 +168,7 @@ protected function parseSmilies($text, $enableHtml = false)
      * Caches code bbcodes to avoid parsing of smileys and other bbcodes inside them.
      *
      * @param string $text
-     * @return  string
+     * @return string
      */
     protected function cacheCodes($text)
     {
@@ -180,8 +188,8 @@ protected function cacheCodes($text)
     /**
      * Returns the hash for an matched code bbcode in the message.
      *
-     * @param array $matches
-     * @return  string
+     * @param list<string> $matches
+     * @return string
      */
     protected function cacheCodesCallback($matches)
     {
@@ -202,7 +210,7 @@ protected function cacheCodesCallback($matches)
      * Reinserts cached code bbcodes.
      *
      * @param string $text
-     * @return  string
+     * @return string
      */
     protected function insertCachedCodes($text)
     {
@@ -251,7 +259,7 @@ protected function isValidTagAttribute(array $tagAttributes, BBCodeAttribute $de
      * Returns a text-only version of given message.
      *
      * @param string $message
-     * @return  string
+     * @return string
      */
     public function stripHTML($message)
     {
diff --git a/wcfsetup/install/files/lib/system/bbcode/SimpleMessageParser.class.php b/wcfsetup/install/files/lib/system/bbcode/SimpleMessageParser.class.php
index 59e6c8172d7..f370bd18477 100644
--- a/wcfsetup/install/files/lib/system/bbcode/SimpleMessageParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/SimpleMessageParser.class.php
@@ -2,7 +2,6 @@
 
 namespace wcf\system\bbcode;
 
-use wcf\data\smiley\Smiley;
 use wcf\data\smiley\SmileyCache;
 use wcf\system\event\EventHandler;
 use wcf\system\SingletonFactory;
@@ -25,19 +24,19 @@ class SimpleMessageParser extends SingletonFactory
 
     /**
      * list of smilies
-     * @var Smiley[]
+     * @var array<string, string>
      */
     protected $smilies = [];
 
     /**
      * cached URLs
-     * @var string[]
+     * @var array<string, string>
      */
     protected $cachedURLs = [];
 
     /**
      * cached e-mails
-     * @var string[]
+     * @var array<string, string>
      */
     protected $cachedEmails = [];
 
@@ -63,7 +62,6 @@ protected function init()
                     continue;
                 }
 
-                /** @var Smiley $smiley */
                 foreach ($categorySmilies as $smiley) {
                     foreach ($smiley->smileyCodes as $smileyCode) {
                         $this->smilies[$smileyCode] = $smiley->getHtml();
@@ -80,7 +78,7 @@ protected function init()
      * @param string $message
      * @param bool $parseURLs
      * @param bool $parseSmilies
-     * @return  string
+     * @return string
      */
     public function parse($message, $parseURLs = true, $parseSmilies = true)
     {
@@ -126,7 +124,7 @@ public function parse($message, $parseURLs = true, $parseSmilies = true)
      * Parses urls.
      *
      * @param string $text
-     * @return  string      text
+     * @return string text
      */
     public function parseURLs($text)
     {
@@ -138,9 +136,9 @@ public function parseURLs($text)
 				www\.(?:' . static::$illegalChars . '\.)+
 				(?:[a-z]{2,63}(?=\b))			# tld
 			)
-			
+
 			(?::\d+)?					# port
-			
+
 			(?:
 				/
 				[^!.,?;"\'<>()\[\]{}\s]*
@@ -172,8 +170,8 @@ public function parseURLs($text)
     /**
      * Returns the hash for an matched URL in the message.
      *
-     * @param array $matches
-     * @return  string
+     * @param list<string> $matches
+     * @return string
      */
     protected function cacheURLsCallback($matches)
     {
@@ -186,8 +184,8 @@ protected function cacheURLsCallback($matches)
     /**
      * Returns the hash for an matched e-mail in the message.
      *
-     * @param array $matches
-     * @return  string
+     * @param list<string> $matches
+     * @return string
      */
     protected function cacheEmailsCallback($matches)
     {
@@ -201,7 +199,7 @@ protected function cacheEmailsCallback($matches)
      * Reinserts cached URLs and e-mails.
      *
      * @param string $text
-     * @return  string
+     * @return string
      */
     protected function insertCachedURLs($text)
     {
@@ -227,7 +225,7 @@ protected function insertCachedURLs($text)
      * Parses smiley codes.
      *
      * @param string $text
-     * @return  string      text
+     * @return string text
      */
     public function parseSmilies($text)
     {
diff --git a/wcfsetup/install/files/lib/system/benchmark/Benchmark.class.php b/wcfsetup/install/files/lib/system/benchmark/Benchmark.class.php
index a3ce2c734ee..fe5b3cf1055 100644
--- a/wcfsetup/install/files/lib/system/benchmark/Benchmark.class.php
+++ b/wcfsetup/install/files/lib/system/benchmark/Benchmark.class.php
@@ -11,6 +11,14 @@
  * @author  Jens Hausdorf, Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @phpstan-type BenchmarkItem array{
+ *  text: string,
+ *  type: int,
+ *  before: float,
+ *  start: float,
+ *  trace: mixed[],
+ * }
  */
 class Benchmark extends SingletonFactory
 {
@@ -27,13 +35,13 @@ class Benchmark extends SingletonFactory
     /**
      * time when the webserver received this request
      * @var float
-     * @since   5.2
+     * @since  5.2
      */
     protected $requestStartTime = 0;
 
     /**
      * benchmark items
-     * @var array
+     * @var list<BenchmarkItem>
      */
     protected $items = [];
 
@@ -63,7 +71,7 @@ protected function init()
      *
      * @param string $text
      * @param int $type
-     * @return  int     index
+     * @return int index
      */
     public function start($text, $type = self::TYPE_OTHER)
     {
@@ -82,6 +90,7 @@ public function start($text, $type = self::TYPE_OTHER)
      * latest benchmark is stopped.
      *
      * @param int $index
+     * @return void
      */
     public function stop($index = null)
     {
@@ -104,7 +113,7 @@ public function stop($index = null)
     /**
      * Returns the execution time.
      *
-     * @return  float
+     * @return float
      */
     public function getExecutionTime()
     {
@@ -116,7 +125,7 @@ public function getExecutionTime()
      * received this request.
      *
      * @return float
-     * @since   5.2
+     * @since 5.2
      */
     public function getRequestExecutionTime()
     {
@@ -128,7 +137,7 @@ public function getRequestExecutionTime()
      * the timestamp when our PHP code is being executed.
      *
      * @return float
-     * @since   5.2
+     * @since 5.2
      */
     public function getOffsetToRequestTime()
     {
@@ -138,7 +147,7 @@ public function getOffsetToRequestTime()
     /**
      * Returns the sql query execution time
      *
-     * @return  float
+     * @return float
      */
     public function getQueryExecutionTime()
     {
@@ -148,7 +157,7 @@ public function getQueryExecutionTime()
     /**
      * Returns the number of executed sql queries.
      *
-     * @return  int
+     * @return int
      */
     public function getQueryCount()
     {
@@ -158,7 +167,7 @@ public function getQueryCount()
     /**
      * Returns the logged items.
      *
-     * @return  array
+     * @return list<BenchmarkItem>
      */
     public function getItems()
     {
@@ -168,7 +177,7 @@ public function getItems()
     /**
      * Returns the current unix timestamp as a float.
      *
-     * @return  float       unix timestamp
+     * @return float unix timestamp
      */
     protected static function getMicrotime()
     {
@@ -180,7 +189,7 @@ protected static function getMicrotime()
      *
      * @param float $startTime
      * @param float $endTime
-     * @return  float
+     * @return float
      */
     protected static function compareMicrotimes($startTime, $endTime)
     {
@@ -190,7 +199,7 @@ protected static function compareMicrotimes($startTime, $endTime)
     /**
      * Returns the formatted peak of memory_usage.
      *
-     * @return  string
+     * @return string
      */
     public function getMemoryUsage()
     {
diff --git a/wcfsetup/install/files/lib/system/box/AbstractBoxController.class.php b/wcfsetup/install/files/lib/system/box/AbstractBoxController.class.php
index 5e31a5935af..3f8607ffd8c 100644
--- a/wcfsetup/install/files/lib/system/box/AbstractBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/AbstractBoxController.class.php
@@ -131,7 +131,7 @@ public function getTitle()
     /**
      * Returns the additional data of the box.
      *
-     * @return  array
+     * @return mixed[]
      */
     protected function getAdditionalData()
     {
@@ -152,6 +152,8 @@ public static function getSupportedPositions()
 
     /**
      * Loads the content of this box.
+     *
+     * @return void
      */
     abstract protected function loadContent();
 }
diff --git a/wcfsetup/install/files/lib/system/box/AbstractCategoriesBoxController.class.php b/wcfsetup/install/files/lib/system/box/AbstractCategoriesBoxController.class.php
index c69d9b1b623..3aa22cd841e 100644
--- a/wcfsetup/install/files/lib/system/box/AbstractCategoriesBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/AbstractCategoriesBoxController.class.php
@@ -120,6 +120,7 @@ protected function getAdditionalData(): array
 
     /**
      * @inheritDoc
+     * @param bool $setConditionData
      */
     public function setBox(Box $box, $setConditionData = true): void
     {
diff --git a/wcfsetup/install/files/lib/system/box/AbstractCommentListBoxController.class.php b/wcfsetup/install/files/lib/system/box/AbstractCommentListBoxController.class.php
index d875455d4b4..5b69865d50c 100644
--- a/wcfsetup/install/files/lib/system/box/AbstractCommentListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/AbstractCommentListBoxController.class.php
@@ -17,6 +17,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<ViewableCommentList>
  */
 abstract class AbstractCommentListBoxController extends AbstractDatabaseObjectListBoxController
 {
@@ -78,7 +80,7 @@ public function __construct()
     /**
      * Applies object type-specific filters to the comments.
      *
-     * @param ViewableCommentList $commentList
+     * @return void
      */
     abstract protected function applyObjectTypeFilters(ViewableCommentList $commentList);
 
diff --git a/wcfsetup/install/files/lib/system/box/AbstractDatabaseObjectListBoxController.class.php b/wcfsetup/install/files/lib/system/box/AbstractDatabaseObjectListBoxController.class.php
index 878e3b2c395..f88d54c534b 100644
--- a/wcfsetup/install/files/lib/system/box/AbstractDatabaseObjectListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/AbstractDatabaseObjectListBoxController.class.php
@@ -27,6 +27,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 abstract class AbstractDatabaseObjectListBoxController extends AbstractBoxController implements IConditionBoxController
 {
@@ -81,7 +83,7 @@ abstract class AbstractDatabaseObjectListBoxController extends AbstractBoxContro
 
     /**
      * database object list used to read the objects displayed in the box
-     * @var DatabaseObjectList
+     * @var TDatabaseObjectList
      */
     public $objectList;
 
@@ -144,9 +146,9 @@ public function __construct()
     /**
      * Adds fields to the given PIP GUI form to create a box for this controller.
      *
-     * @param IFormDocument $form
      * @param string $objectType
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function addPipGuiFormFields(IFormDocument $form, $objectType)
     {
@@ -211,8 +213,8 @@ public function addPipGuiFormFields(IFormDocument $form, $objectType)
      *
      * @param \DOMElement $element
      * @param bool $saveData
-     * @return  array
-     * @since   5.2
+     * @return array{sortField?: string, sortOrder?: string, limit?: string}
+     * @since 5.2
      */
     public function getPipGuiElementData(\DOMElement $element, $saveData = false)
     {
@@ -220,7 +222,7 @@ public function getPipGuiElementData(\DOMElement $element, $saveData = false)
         foreach (['sortField', 'sortOrder', 'limit'] as $optionalElementName) {
             $optionalElement = $element->getElementsByTagName($optionalElementName)->item(0);
             if ($optionalElement !== null) {
-                $data[$optionalElementName] = $optionalElement->nodeValue;
+                $data[$optionalElementName] = $optionalElement->textContent;
             }
         }
 
@@ -281,7 +283,7 @@ public function getConditionsTemplate()
     /**
      * Returns the database object list used to read the objects displayed in the box.
      *
-     * @return ?DatabaseObjectList
+     * @return ?TDatabaseObjectList
      */
     abstract protected function getObjectList();
 
@@ -363,6 +365,8 @@ public function readConditions()
 
     /**
      * Reads the displayed database objects.
+     *
+     * @return void
      */
     protected function readObjects()
     {
@@ -395,6 +399,7 @@ public function saveAdditionalData()
      *
      * @param Box $box box object
      * @param bool $setConditionData if true, the condition object types are populated with the box conditions' data
+     * @return void
      */
     public function setBox(Box $box, $setConditionData = true)
     {
@@ -454,9 +459,8 @@ public function validateConditions()
     }
 
     /**
-     * @param \DOMElement $element
-     * @param IFormDocument $form
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function writePipGuiEntry(\DOMElement $element, IFormDocument $form)
     {
diff --git a/wcfsetup/install/files/lib/system/box/ArticleListBoxController.class.php b/wcfsetup/install/files/lib/system/box/ArticleListBoxController.class.php
index 2b63779b71c..542a5227272 100644
--- a/wcfsetup/install/files/lib/system/box/ArticleListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/ArticleListBoxController.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<AccessibleArticleList>
  */
 class ArticleListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/BoxHandler.class.php b/wcfsetup/install/files/lib/system/box/BoxHandler.class.php
index 65642c69bf5..d53e1c3c0b6 100644
--- a/wcfsetup/install/files/lib/system/box/BoxHandler.class.php
+++ b/wcfsetup/install/files/lib/system/box/BoxHandler.class.php
@@ -71,7 +71,8 @@ protected function init()
      * @param string $boxIdentifier
      * @param string $conditionDefinition
      * @param string $conditionObjectType
-     * @param array $conditionData
+     * @param mixed[] $conditionData
+     * @return void
      * @throws  \InvalidArgumentException
      * @deprecated 6.1 use `CreateBoxCondition` instead
      */
@@ -122,7 +123,8 @@ public function getBoxByIdentifier($identifier)
      * @param string $boxIdentifier
      * @param string[] $pageIdentifiers
      * @param bool $visible
-     * @throws  \InvalidArgumentException
+     * @return void
+     * @throws \InvalidArgumentException
      * @deprecated 6.1 use `CreateBoxCondition` instead
      */
     public function addBoxToPageAssignments($boxIdentifier, array $pageIdentifiers, $visible = true)
@@ -150,6 +152,8 @@ public function sidebarLeftHasMenu()
 
     /**
      * Disables the loading of the box layout for the active page.
+     *
+     * @return void
      */
     public static function disablePageLayout()
     {
diff --git a/wcfsetup/install/files/lib/system/box/FollowingsOnlineBoxController.class.php b/wcfsetup/install/files/lib/system/box/FollowingsOnlineBoxController.class.php
index c8a3eca1568..5b9cf8675cb 100644
--- a/wcfsetup/install/files/lib/system/box/FollowingsOnlineBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/FollowingsOnlineBoxController.class.php
@@ -13,6 +13,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<UsersOnlineList>
  */
 class FollowingsOnlineBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/IBoxController.class.php b/wcfsetup/install/files/lib/system/box/IBoxController.class.php
index 48a1d628606..95e6a29fe4b 100644
--- a/wcfsetup/install/files/lib/system/box/IBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/IBoxController.class.php
@@ -18,14 +18,14 @@ interface IBoxController
     /**
      * Returns the content of this box.
      *
-     * @return  string
+     * @return string
      */
     public function getContent();
 
     /**
      * Returns false if this box has no content.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasContent();
 
@@ -34,28 +34,28 @@ public function hasContent();
      *
      * Note: The box itself checks if the active user can access the returned media file.
      *
-     * @return  ViewableMedia|null
+     * @return ?ViewableMedia
      */
     public function getImage();
 
     /**
      * Returns the title link of this box.
      *
-     * @return  string
+     * @return string
      */
     public function getLink();
 
     /**
      * Returns true if this box has a title link.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasLink();
 
     /**
      * Returns the database object of this box.
      *
-     * @return  Box
+     * @return Box
      */
     public function getBox();
 
@@ -63,11 +63,14 @@ public function getBox();
      * Sets the database object of this box.
      *
      * @param Box $box
+     * @return void
      */
     public function setBox(Box $box);
 
     /**
      * Saves additional box data for box set via `setBox()`.
+     *
+     * @return void
      */
     public function saveAdditionalData();
 
@@ -76,15 +79,15 @@ public function saveAdditionalData();
      * apply the default behavior as seen in previous versions. Only supported for
      * system-type boxes.
      *
-     * @return      string|null
-     * @since       5.2
+     * @return ?string
+     * @since 5.2
      */
     public function getTitle();
 
     /**
      * Returns a list of supported box positions.
      *
-     * @return  string[]
+     * @return string[]
      */
     public static function getSupportedPositions();
 }
diff --git a/wcfsetup/install/files/lib/system/box/IConditionBoxController.class.php b/wcfsetup/install/files/lib/system/box/IConditionBoxController.class.php
index 8e6f566c4ba..41620fd4599 100644
--- a/wcfsetup/install/files/lib/system/box/IConditionBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/IConditionBoxController.class.php
@@ -17,31 +17,35 @@ interface IConditionBoxController extends IBoxController
     /**
      * Returns the name of the object type definition for the box controller's condition object types.
      *
-     * @return  string
+     * @return string
      */
     public function getConditionDefinition();
 
     /**
      * Returns the condition objects types registered for the dynamic box controller.
      *
-     * @return  ObjectType[]
+     * @return ObjectType[]
      */
     public function getConditionObjectTypes();
 
     /**
      * Returns the template containing the box conditions.
      *
-     * @return  string
+     * @return string
      */
     public function getConditionsTemplate();
 
     /**
      * Reads the box conditions.
+     *
+     * @return void
      */
     public function readConditions();
 
     /**
      * Validates the read conditions for the box.
+     *
+     * @return void
      */
     public function validateConditions();
 }
diff --git a/wcfsetup/install/files/lib/system/box/PageCommentListBoxController.class.php b/wcfsetup/install/files/lib/system/box/PageCommentListBoxController.class.php
index 1ab9051b1ab..6c4154676a0 100644
--- a/wcfsetup/install/files/lib/system/box/PageCommentListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/PageCommentListBoxController.class.php
@@ -14,7 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property-read StructuredCommentList $objectList
+ * @extends AbstractDatabaseObjectListBoxController<StructuredCommentList>
  */
 class PageCommentListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/RecentActivityListBoxController.class.php b/wcfsetup/install/files/lib/system/box/RecentActivityListBoxController.class.php
index b6ec1b372fc..de288cf49d2 100644
--- a/wcfsetup/install/files/lib/system/box/RecentActivityListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/RecentActivityListBoxController.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\box;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\user\activity\event\ViewableUserActivityEventList;
 use wcf\data\user\ignore\UserIgnore;
 use wcf\system\condition\IObjectListCondition;
@@ -18,7 +20,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @property    ViewableUserActivityEventList $objectList
+ * @extends AbstractDatabaseObjectListBoxController<ViewableUserActivityEventList>
  */
 class RecentActivityListBoxController extends AbstractDatabaseObjectListBoxController
 {
@@ -192,7 +194,7 @@ public function getFilteredList()
 
         if ($this->conditionDefinition) {
             foreach ($this->box->getConditions() as $condition) {
-                /** @var IObjectListCondition $processor */
+                /** @var IObjectListCondition<DatabaseObjectList<DatabaseObject>> $processor */
                 $processor = $condition->getObjectType()->getProcessor();
                 $processor->addObjectListCondition($this->objectList, $condition->conditionData);
             }
diff --git a/wcfsetup/install/files/lib/system/box/StaffOnlineListBoxController.class.php b/wcfsetup/install/files/lib/system/box/StaffOnlineListBoxController.class.php
index 589b0adfd37..700e6b945f1 100644
--- a/wcfsetup/install/files/lib/system/box/StaffOnlineListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/StaffOnlineListBoxController.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<UsersOnlineList>
  */
 class StaffOnlineListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/TodaysBirthdaysBoxController.class.php b/wcfsetup/install/files/lib/system/box/TodaysBirthdaysBoxController.class.php
index 11dd4fa87ee..d42ef6aca41 100644
--- a/wcfsetup/install/files/lib/system/box/TodaysBirthdaysBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/TodaysBirthdaysBoxController.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\box;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\user\option\UserOption;
 use wcf\system\cache\builder\UserOptionCacheBuilder;
 use wcf\system\cache\runtime\UserProfileRuntimeCache;
@@ -17,6 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<DatabaseObjectList<DatabaseObject>>
  */
 class TodaysBirthdaysBoxController extends AbstractDatabaseObjectListBoxController
 {
@@ -156,6 +159,7 @@ protected function loadContent()
      * Filters given user ids.
      *
      * @param int[] $userIDs
+     * @return void
      */
     protected function filterUserIDs(&$userIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/box/UserListBoxController.class.php b/wcfsetup/install/files/lib/system/box/UserListBoxController.class.php
index 69e20fd4b4f..5675a44cc85 100644
--- a/wcfsetup/install/files/lib/system/box/UserListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/UserListBoxController.class.php
@@ -21,6 +21,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<UserProfileList>
  */
 class UserListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/UserOnlineListBoxController.class.php b/wcfsetup/install/files/lib/system/box/UserOnlineListBoxController.class.php
index 78e3c54ddec..6764536de14 100644
--- a/wcfsetup/install/files/lib/system/box/UserOnlineListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/UserOnlineListBoxController.class.php
@@ -15,7 +15,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @property    UsersOnlineList $objectList
+ * @extends AbstractDatabaseObjectListBoxController<UsersOnlineList>
  */
 class UserOnlineListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/UserTrophyListBoxController.class.php b/wcfsetup/install/files/lib/system/box/UserTrophyListBoxController.class.php
index 72cb886f332..8b80b22b50b 100644
--- a/wcfsetup/install/files/lib/system/box/UserTrophyListBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/UserTrophyListBoxController.class.php
@@ -16,7 +16,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @property    UserTrophyList $objectList
+ * @extends AbstractDatabaseObjectListBoxController<UserTrophyList>
  */
 class UserTrophyListBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/WhoWasOnlineBoxController.class.php b/wcfsetup/install/files/lib/system/box/WhoWasOnlineBoxController.class.php
index 87734375c06..aa3d8aa3204 100644
--- a/wcfsetup/install/files/lib/system/box/WhoWasOnlineBoxController.class.php
+++ b/wcfsetup/install/files/lib/system/box/WhoWasOnlineBoxController.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\box;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\user\online\UserOnline;
 use wcf\data\user\online\UsersOnlineList;
 use wcf\data\user\UserProfile;
@@ -19,6 +20,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractDatabaseObjectListBoxController<DatabaseObjectList<DatabaseObject>>
  */
 class WhoWasOnlineBoxController extends AbstractDatabaseObjectListBoxController
 {
diff --git a/wcfsetup/install/files/lib/system/box/command/CreateBoxCondition.class.php b/wcfsetup/install/files/lib/system/box/command/CreateBoxCondition.class.php
index e224f376ff3..dcc0f3a1cec 100644
--- a/wcfsetup/install/files/lib/system/box/command/CreateBoxCondition.class.php
+++ b/wcfsetup/install/files/lib/system/box/command/CreateBoxCondition.class.php
@@ -18,6 +18,9 @@
  */
 final class CreateBoxCondition
 {
+    /**
+     * @param mixed[] $conditionData
+     */
     public function __construct(
         private readonly string $boxIdentifier,
         private readonly string $conditionDefinition,
@@ -29,7 +32,7 @@ public function __construct(
     /**
      * @throws \InvalidArgumentException
      */
-    public function __invoke()
+    public function __invoke(): void
     {
         $objectTypeID = $this->getObjectTypeID();
         if (!$objectTypeID) {
diff --git a/wcfsetup/install/files/lib/system/box/command/CreateBoxToPageAssignments.class.php b/wcfsetup/install/files/lib/system/box/command/CreateBoxToPageAssignments.class.php
index 1d312a042ed..c78be25db7a 100644
--- a/wcfsetup/install/files/lib/system/box/command/CreateBoxToPageAssignments.class.php
+++ b/wcfsetup/install/files/lib/system/box/command/CreateBoxToPageAssignments.class.php
@@ -15,10 +15,12 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
- * @property-read array<string> $pageIdentifiers
  */
 final class CreateBoxToPageAssignments
 {
+    /**
+     * @param string[] $pageIdentifiers
+     */
     public function __construct(
         private readonly string $boxIdentifier,
         private readonly array $pageIdentifiers,
@@ -29,7 +31,7 @@ public function __construct(
     /**
      * @throws \InvalidArgumentException
      */
-    public function __invoke()
+    public function __invoke(): void
     {
         $box = Box::getBoxByIdentifier($this->boxIdentifier);
         if ($box === null) {
diff --git a/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumb.class.php b/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumb.class.php
index 69ba6ab9ea9..e515f0a8bf9 100644
--- a/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumb.class.php
+++ b/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumb.class.php
@@ -39,6 +39,7 @@ public function __construct($label, $url)
      * Sets the displayed label.
      *
      * @param string $label
+     * @return void
      */
     public function setLabel($label)
     {
@@ -51,6 +52,7 @@ public function setLabel($label)
      *
      * @param string $url
      * @param bool $appendSession This parameter is unused as of version 3.0
+     * @return void
      */
     public function setURL($url, $appendSession = false)
     {
diff --git a/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumbs.class.php b/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumbs.class.php
index 2204b01a147..4b3db2c2e2f 100644
--- a/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumbs.class.php
+++ b/wcfsetup/install/files/lib/system/breadcrumb/Breadcrumbs.class.php
@@ -13,6 +13,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements \Iterator<int, Breadcrumb>
  */
 final class Breadcrumbs extends SingletonFactory implements \Countable, \Iterator
 {
@@ -20,12 +22,12 @@ final class Breadcrumbs extends SingletonFactory implements \Countable, \Iterato
      * list of breadcrumbs
      * @var Breadcrumb[]
      */
-    protected $items;
+    private array $items;
 
     /**
      * Current iterator-index
      */
-    protected int $index = 0;
+    private int $index = 0;
 
     /**
      * Returns the list of breadcrumbs.
@@ -34,7 +36,7 @@ final class Breadcrumbs extends SingletonFactory implements \Countable, \Iterato
      */
     public function get(): array
     {
-        if ($this->items === null) {
+        if (!isset($this->items)) {
             $this->loadBreadcrumbs();
         }
 
@@ -44,7 +46,7 @@ public function get(): array
     /**
      * Loads the list of breadcrumbs.
      */
-    protected function loadBreadcrumbs(): void
+    private function loadBreadcrumbs(): void
     {
         $this->items = [];
         $locations = PageLocationManager::getInstance()->getLocations();
@@ -83,7 +85,7 @@ protected function loadBreadcrumbs(): void
      */
     public function count(): int
     {
-        if ($this->items === null) {
+        if (!isset($this->items)) {
             $this->loadBreadcrumbs();
         }
 
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/AbstractBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/AbstractBulkProcessingAction.class.php
index 591a3bcf8a6..671cf89cb55 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/AbstractBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/AbstractBulkProcessingAction.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\bulk\processing;
 
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\AbstractObjectTypeProcessor;
 
 /**
@@ -11,6 +12,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
+ * @implements IBulkProcessingAction<TDatabaseObjectList>
  */
 abstract class AbstractBulkProcessingAction extends AbstractObjectTypeProcessor implements IBulkProcessingAction
 {
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/IBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/IBulkProcessingAction.class.php
index 7f682130df2..73e7d95f61b 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/IBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/IBulkProcessingAction.class.php
@@ -11,6 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 interface IBulkProcessingAction
 {
@@ -18,15 +20,16 @@ interface IBulkProcessingAction
      * Executes the bulk processing action on all objects in the given object
      * list.
      *
-     * @param DatabaseObjectList $objectList
-     * @throws  \InvalidArgumentException   if given object list cannot be handled by the action
+     * @param TDatabaseObjectList $objectList
+     * @return void
+     * @throws \InvalidArgumentException if given object list cannot be handled by the action
      */
     public function executeAction(DatabaseObjectList $objectList);
 
     /**
      * Returns the output for setting additional action parameters.
      *
-     * @return  string
+     * @return string
      */
     public function getHTML();
 
@@ -34,36 +37,41 @@ public function getHTML();
      * Returns an object list which will be populated with conditions to read
      * the processed objects.
      *
-     * @return  DatabaseObjectList
+     * @return TDatabaseObjectList
      */
     public function getObjectList();
 
     /**
      * Returns true if the action is available for the active user.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAvailable();
 
     /**
      * Reads additional parameters to execute the action.
+     *
+     * @return void
      */
     public function readFormParameters();
 
     /**
      * Resets the internally stored additional action parameters.
+     *
+     * @return void
      */
     public function reset();
 
     /**
      * Validates the additional action parameters.
+     *
+     * @return void
      */
     public function validate();
 
     /**
      * Returns true if the action can be executed in a worker.
      *
-     * @return  bool
      * @since 6.1
      */
     public function canRunInWorker(): bool;
@@ -71,7 +79,7 @@ public function canRunInWorker(): bool;
     /**
      * Returns the additional action parameters that should be serialized.
      *
-     * @return  array
+     * @return mixed[]
      * @since 6.1
      */
     public function getAdditionalParameters(): array;
@@ -79,7 +87,7 @@ public function getAdditionalParameters(): array;
     /**
      * Loads the additional action parameters from the given data.
      *
-     * @param array $data
+     * @param mixed[] $data
      * @since 6.1
      */
     public function loadAdditionalParameters(array $data): void;
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserBulkProcessingAction.class.php
index 02949f18f4e..ea4d5837f74 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserBulkProcessingAction.class.php
@@ -16,6 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractBulkProcessingAction<UserList>
  */
 abstract class AbstractUserBulkProcessingAction extends AbstractBulkProcessingAction
 {
@@ -31,8 +33,7 @@ public function getObjectList()
      * Returns all users who the active user can access due to their user group
      * association.
      *
-     * @param UserList $userList
-     * @return  User[]
+     * @return array<int, User>
      */
     protected function getAccessibleUsers(UserList $userList)
     {
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserGroupsUserBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserGroupsUserBulkProcessingAction.class.php
index 839cbee1ecc..bf04eb3bc22 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserGroupsUserBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/user/AbstractUserGroupsUserBulkProcessingAction.class.php
@@ -6,8 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\group\UserGroup;
 use wcf\data\user\UserEditor;
-use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\user\storage\UserStorageHandler;
 use wcf\system\WCF;
@@ -60,10 +58,6 @@ public function __construct(DatabaseObject $object)
      */
     public function executeAction(DatabaseObjectList $objectList)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $users = $this->getAccessibleUsers($objectList);
 
         if (!empty($users)) {
@@ -81,7 +75,7 @@ public function executeAction(DatabaseObjectList $objectList)
     /**
      * Execute the action for the given user.
      *
-     * @param UserEditor $user
+     * @return void
      */
     abstract protected function executeUserAction(UserEditor $user);
 
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/user/DeleteUserBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/user/DeleteUserBulkProcessingAction.class.php
index 9f023e99616..1d577eecd71 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/user/DeleteUserBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/user/DeleteUserBulkProcessingAction.class.php
@@ -4,8 +4,6 @@
 
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\UserAction;
-use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -23,10 +21,6 @@ class DeleteUserBulkProcessingAction extends AbstractUserBulkProcessingAction
      */
     public function executeAction(DatabaseObjectList $objectList)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $users = $this->getAccessibleUsers($objectList);
 
         if (!empty($users)) {
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/user/ExportMailAddressUserBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/user/ExportMailAddressUserBulkProcessingAction.class.php
index 6d7e2631ebe..f04d8133880 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/user/ExportMailAddressUserBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/user/ExportMailAddressUserBulkProcessingAction.class.php
@@ -3,8 +3,6 @@
 namespace wcf\system\bulk\processing\user;
 
 use wcf\data\DatabaseObjectList;
-use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 use wcf\util\StringUtil;
 
@@ -47,10 +45,6 @@ class ExportMailAddressUserBulkProcessingAction extends AbstractUserBulkProcessi
      */
     public function executeAction(DatabaseObjectList $objectList)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $this->executed = true;
 
         // send content type
diff --git a/wcfsetup/install/files/lib/system/bulk/processing/user/SendMailUserBulkProcessingAction.class.php b/wcfsetup/install/files/lib/system/bulk/processing/user/SendMailUserBulkProcessingAction.class.php
index f596f11f7a9..097ba282395 100644
--- a/wcfsetup/install/files/lib/system/bulk/processing/user/SendMailUserBulkProcessingAction.class.php
+++ b/wcfsetup/install/files/lib/system/bulk/processing/user/SendMailUserBulkProcessingAction.class.php
@@ -3,8 +3,6 @@
 namespace wcf\system\bulk\processing\user;
 
 use wcf\data\DatabaseObjectList;
-use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 use wcf\util\StringUtil;
@@ -48,10 +46,6 @@ class SendMailUserBulkProcessingAction extends AbstractUserBulkProcessingAction
      */
     public function executeAction(DatabaseObjectList $objectList)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (\count($objectList)) {
             // save config in session
             $userMailData = WCF::getSession()->getVar('userMailData');
diff --git a/wcfsetup/install/files/lib/system/cache/CacheHandler.class.php b/wcfsetup/install/files/lib/system/cache/CacheHandler.class.php
index d9ec9af9c7f..0428a03c287 100644
--- a/wcfsetup/install/files/lib/system/cache/CacheHandler.class.php
+++ b/wcfsetup/install/files/lib/system/cache/CacheHandler.class.php
@@ -4,6 +4,7 @@
 
 use wcf\system\cache\builder\ICacheBuilder;
 use wcf\system\cache\source\DiskCacheSource;
+use wcf\system\cache\source\ICacheSource;
 use wcf\system\exception\SystemException;
 use wcf\system\SingletonFactory;
 
@@ -17,14 +18,11 @@
 class CacheHandler extends SingletonFactory
 {
     /**
-     * cache source object
-     * @var \wcf\system\cache\source\ICacheSource
+     * @var ICacheSource
      */
     protected $cacheSource;
 
-    /**
-     * Creates a new CacheHandler object.
-     */
+    #[\Override]
     protected function init()
     {
         // init cache source object
@@ -49,8 +47,8 @@ protected function init()
     /**
      * Flush cache for given resource.
      *
-     * @param ICacheBuilder $cacheBuilder
-     * @param array $parameters
+     * @param mixed[] $parameters
+     * @return void
      */
     public function flush(ICacheBuilder $cacheBuilder, array $parameters)
     {
@@ -59,6 +57,8 @@ public function flush(ICacheBuilder $cacheBuilder, array $parameters)
 
     /**
      * Flushes the entire cache.
+     *
+     * @return void
      */
     public function flushAll()
     {
@@ -68,9 +68,8 @@ public function flushAll()
     /**
      * Returns cached value for given resource, false if no cache exists.
      *
-     * @param ICacheBuilder $cacheBuilder
-     * @param array $parameters
-     * @return  mixed
+     * @param mixed[] $parameters
+     * @return mixed
      */
     public function get(ICacheBuilder $cacheBuilder, array $parameters)
     {
@@ -83,9 +82,9 @@ public function get(ICacheBuilder $cacheBuilder, array $parameters)
     /**
      * Caches a value for given resource,
      *
-     * @param ICacheBuilder $cacheBuilder
-     * @param array $parameters
-     * @param array $data
+     * @param mixed[] $parameters
+     * @param mixed[] $data
+     * @return void
      */
     public function set(ICacheBuilder $cacheBuilder, array $parameters, array $data)
     {
@@ -99,8 +98,8 @@ public function set(ICacheBuilder $cacheBuilder, array $parameters, array $data)
     /**
      * Returns cache index hash.
      *
-     * @param array $parameters
-     * @return  string
+     * @param mixed[] $parameters
+     * @return string
      */
     public function getCacheIndex(array $parameters)
     {
@@ -110,9 +109,8 @@ public function getCacheIndex(array $parameters)
     /**
      * Builds cache name.
      *
-     * @param ICacheBuilder $cacheBuilder
-     * @param array $parameters
-     * @return  string
+     * @param mixed[] $parameters
+     * @return string
      */
     protected function getCacheName(ICacheBuilder $cacheBuilder, array $parameters = [])
     {
@@ -131,7 +129,7 @@ protected function getCacheName(ICacheBuilder $cacheBuilder, array $parameters =
     /**
      * Returns the cache source object.
      *
-     * @return  \wcf\system\cache\source\ICacheSource
+     * @return ICacheSource
      */
     public function getCacheSource()
     {
@@ -141,8 +139,8 @@ public function getCacheSource()
     /**
      * Unifies parameter order, numeric indices will be discarded.
      *
-     * @param array $parameters
-     * @return  array
+     * @param mixed[] $parameters
+     * @return mixed[]
      */
     protected function orderParameters($parameters)
     {
@@ -161,8 +159,8 @@ protected function orderParameters($parameters)
     public function sanityCheck(): bool
     {
         if (
-            CACHE_SOURCE_TYPE != 'disk'
-            && \get_class(CacheHandler::getInstance()->getCacheSource()) === \wcf\system\cache\source\DiskCacheSource::class
+            CACHE_SOURCE_TYPE !== 'disk'
+            && \get_class(CacheHandler::getInstance()->getCacheSource()) === DiskCacheSource::class
         ) {
             return false;
         }
diff --git a/wcfsetup/install/files/lib/system/cache/builder/AbstractCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/AbstractCacheBuilder.class.php
index b8f52549efc..8d87429480f 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/AbstractCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/AbstractCacheBuilder.class.php
@@ -75,7 +75,8 @@ public function reset(array $parameters = [])
     /**
      * Rebuilds cache for current resource.
      *
-     * @param array $parameters
+     * @param mixed[] $parameters
+     * @return mixed|mixed[]
      */
     abstract protected function rebuild(array $parameters);
 }
diff --git a/wcfsetup/install/files/lib/system/cache/builder/AbstractSortedUserCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/AbstractSortedUserCacheBuilder.class.php
index f0abfc7d26e..b820fb86cc3 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/AbstractSortedUserCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/AbstractSortedUserCacheBuilder.class.php
@@ -3,6 +3,8 @@
 namespace wcf\system\cache\builder;
 
 use wcf\data\condition\Condition;
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\user\UserList;
 use wcf\system\condition\IObjectListCondition;
 
@@ -62,7 +64,7 @@ protected function rebuild(array $parameters)
         if (isset($parameters['conditions'])) {
             /** @var Condition $condition */
             foreach ($parameters['conditions'] as $condition) {
-                /** @var IObjectListCondition $processor */
+                /** @var IObjectListCondition<DatabaseObjectList<DatabaseObject>> $processor */
                 $processor = $condition->getObjectType()->getProcessor();
                 $processor->addObjectListCondition($userProfileList, $condition->conditionData);
             }
diff --git a/wcfsetup/install/files/lib/system/cache/builder/ICacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/ICacheBuilder.class.php
index 9c40050ffcc..6fafff4c414 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/ICacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/ICacheBuilder.class.php
@@ -14,16 +14,16 @@ interface ICacheBuilder
     /**
      * Returns the data that ought to be cached.
      *
-     * @param array $parameters
+     * @param mixed[] $parameters
      * @param string $arrayIndex
-     * @return  mixed
+     * @return mixed
      */
     public function getData(array $parameters = [], $arrayIndex = '');
 
     /**
      * Returns maximum lifetime for cache resource.
      *
-     * @return  int
+     * @return int
      */
     public function getMaxLifetime();
 
@@ -31,7 +31,8 @@ public function getMaxLifetime();
      * Flushes cache. If no parameters are given, all caches starting with
      * the same cache name will be flushed too.
      *
-     * @param array $parameters
+     * @param mixed[] $parameters
+     * @return void
      */
     public function reset(array $parameters = []);
 }
diff --git a/wcfsetup/install/files/lib/system/cache/builder/LabelCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/LabelCacheBuilder.class.php
index 9e6726190db..0158c8517d9 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/LabelCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/LabelCacheBuilder.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\cache\builder;
 
+use wcf\data\acl\option\ACLOption;
 use wcf\data\label\group\LabelGroupList;
 use wcf\data\label\group\ViewableLabelGroup;
 use wcf\data\label\LabelList;
@@ -13,6 +14,10 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type LabelCache array{
+ *  options: array<int, ACLOption>,
+ *  groups: array<int, ViewableLabelGroup>,
+ * }
  */
 class LabelCacheBuilder extends AbstractCacheBuilder
 {
diff --git a/wcfsetup/install/files/lib/system/cache/builder/LanguageCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/LanguageCacheBuilder.class.php
index 9912756fa4f..abc3de6c8c2 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/LanguageCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/LanguageCacheBuilder.class.php
@@ -3,7 +3,9 @@
 namespace wcf\system\cache\builder;
 
 use wcf\data\DatabaseObject;
+use wcf\data\language\category\LanguageCategory;
 use wcf\data\language\category\LanguageCategoryList;
+use wcf\data\language\Language;
 use wcf\data\language\LanguageList;
 
 /**
@@ -12,6 +14,15 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type LanguageCache array{
+ *  codes: array<string, int>,
+ *  countryCodes: array<int, string>,
+ *  languages: array<int, Language>,
+ *  default: int,
+ *  categories: array<string, LanguageCategory>,
+ *  categoryIDs: array<int, string>,
+ *  multilingualismEnabled: bool,
+ * }
  */
 class LanguageCacheBuilder extends AbstractCacheBuilder
 {
diff --git a/wcfsetup/install/files/lib/system/cache/builder/RoutingCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/RoutingCacheBuilder.class.php
index c6bcfe9bea8..2536635ff56 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/RoutingCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/RoutingCacheBuilder.class.php
@@ -44,8 +44,14 @@ protected function rebuild(array $parameters)
      * declares a different application that will be used instead without actually migrating
      * the page to a different application.
      *
-     * @param array $customUrls
-     * @return array
+     * @param array{
+     *  lookup: array<string, array<string, string>>,
+     *  reverse: array<string, array<string, string>>,
+     * } $customUrls
+     * @return array{
+     *  lookup: array<string, array<string, string>>,
+     *  reverse: array<string, array<string, string>>,
+     * }
      */
     protected function getApplicationOverrides(array &$customUrls)
     {
@@ -115,7 +121,10 @@ protected function getApplicationOverrides(array &$customUrls)
      * and environment level to prevent any issues with controllers with the same name but
      * correct spelling to be incorrectly handled.
      *
-     * @return  array
+     * @return array<string, array{
+     *  acp: array<string, string>,
+     *  frontend: array<string, string>,
+     * }>|array{}
      */
     protected function getCaseInsensitiveControllers()
     {
@@ -169,7 +178,10 @@ protected function getCaseInsensitiveControllers()
      * Builds up a lookup and a reverse lookup list per application in order to resolve
      * custom page mappings.
      *
-     * @return  array
+     * @return array{
+     *  lookup: array<string, array<string, string>>,
+     *  reverse: array<string, array<string, string>>,
+     * }
      */
     protected function getCustomUrls()
     {
diff --git a/wcfsetup/install/files/lib/system/cache/builder/TagCloudCacheBuilder.class.php b/wcfsetup/install/files/lib/system/cache/builder/TagCloudCacheBuilder.class.php
index 8a7ca6b62c3..9686365fb5b 100644
--- a/wcfsetup/install/files/lib/system/cache/builder/TagCloudCacheBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/cache/builder/TagCloudCacheBuilder.class.php
@@ -75,6 +75,8 @@ protected function parseLanguageIDs(array $parameters)
 
     /**
      * Reads associated tags.
+     *
+     * @return void
      */
     protected function getTags()
     {
diff --git a/wcfsetup/install/files/lib/system/cache/command/ClearCache.class.php b/wcfsetup/install/files/lib/system/cache/command/ClearCache.class.php
index 28816c755b2..50f31330af6 100644
--- a/wcfsetup/install/files/lib/system/cache/command/ClearCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/command/ClearCache.class.php
@@ -28,7 +28,7 @@ public function __construct()
         $this->eventHandler = EventHandler::getInstance();
     }
 
-    public function __invoke()
+    public function __invoke(): void
     {
         OptionEditor::resetCache();
 
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/AbstractRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/AbstractRuntimeCache.class.php
index d07fbb03216..7d63d6f33d3 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/AbstractRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/AbstractRuntimeCache.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\cache\runtime;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\DatabaseObjectList;
 use wcf\system\SingletonFactory;
 
@@ -13,6 +14,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @template TDatabaseObjectList of DatabaseObjectList
+ * @implements IRuntimeCache<TDatabaseObject>
  */
 abstract class AbstractRuntimeCache extends SingletonFactory implements IRuntimeCache
 {
@@ -30,21 +34,17 @@ abstract class AbstractRuntimeCache extends SingletonFactory implements IRuntime
 
     /**
      * cached DatabaseObject objects
-     * @var DatabaseObject[]
+     * @var TDatabaseObject[]
      */
     protected $objects = [];
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function cacheObjectID($objectID)
     {
         $this->cacheObjectIDs([$objectID]);
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function cacheObjectIDs(array $objectIDs)
     {
         foreach ($objectIDs as $objectID) {
@@ -56,6 +56,8 @@ public function cacheObjectIDs(array $objectIDs)
 
     /**
      * Fetches the objects for the pending object ids.
+     *
+     * @return void
      */
     protected function fetchObjects()
     {
@@ -74,17 +76,13 @@ protected function fetchObjects()
         $this->objectIDs = [];
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function getCachedObjects()
     {
         return $this->objects;
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function getObject($objectID)
     {
         if (\array_key_exists($objectID, $this->objects)) {
@@ -101,16 +99,14 @@ public function getObject($objectID)
     /**
      * Returns a database object list object to fetch cached objects.
      *
-     * @return  DatabaseObjectList
+     * @return TDatabaseObjectList
      */
     protected function getObjectList()
     {
         return new $this->listClassName();
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function getObjects(array $objectIDs)
     {
         $objects = [];
@@ -137,17 +133,13 @@ public function getObjects(array $objectIDs)
         return $objects;
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function removeObject($objectID)
     {
         $this->removeObjects([$objectID]);
     }
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function removeObjects(array $objectIDs)
     {
         foreach ($objectIDs as $objectID) {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/AttachmentRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/AttachmentRuntimeCache.class.php
index 7d13363c55e..070323f34a8 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/AttachmentRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/AttachmentRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method  Attachment[]         getCachedObjects()
- * @method  Attachment|null      getObject($objectID)
- * @method  Attachment[]         getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<Attachment, AttachmentList>
  */
 final class AttachmentRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/CommentResponseRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/CommentResponseRuntimeCache.class.php
index 4fe31d687f5..d04dfb3e465 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/CommentResponseRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/CommentResponseRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  (CommentResponse|null)[]    getCachedObjects()
- * @method  ?CommentResponse getObject($objectID)
- * @method  (CommentResponse|null)[]    getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<CommentResponse, CommentResponseList>
  */
 class CommentResponseRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/CommentRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/CommentRuntimeCache.class.php
index 7c16de370fe..c1eddfa948d 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/CommentRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/CommentRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  (Comment|null)[]    getCachedObjects()
- * @method  ?Comment getObject($objectID)
- * @method  (Comment|null)[]    getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<Comment, CommentList>
  */
 class CommentRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/FileRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/FileRuntimeCache.class.php
index d08713019a6..7652c7f38c6 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/FileRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/FileRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method  File[]      getCachedObjects()
- * @method  File|null   getObject($objectID)
- * @method  File[]      getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<File, FileList>
  */
 class FileRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/IRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/IRuntimeCache.class.php
index 000e112b4c9..9f5a64f38fe 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/IRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/IRuntimeCache.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\cache\runtime;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 
 /**
  * Handles runtime caches to centrally store objects fetched during runtime for reuse.
@@ -11,6 +12,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
  */
 interface IRuntimeCache
 {
@@ -19,6 +21,7 @@ interface IRuntimeCache
      * this id will also be fetched.
      *
      * @param int $objectID
+     * @return void
      */
     public function cacheObjectID($objectID);
 
@@ -27,13 +30,14 @@ public function cacheObjectID($objectID);
      * these ids will also be fetched.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function cacheObjectIDs(array $objectIDs);
 
     /**
      * Returns all currently cached objects.
      *
-     * @return  DatabaseObject[]
+     * @return array<int, ?TDatabaseObject>
      */
     public function getCachedObjects();
 
@@ -43,7 +47,7 @@ public function getCachedObjects();
      * during this method call and the object, if existing, will be returned.
      *
      * @param int $objectID
-     * @return  DatabaseObject|null
+     * @return ?TDatabaseObject
      */
     public function getObject($objectID);
 
@@ -54,7 +58,7 @@ public function getObject($objectID);
      * during this method call and the objects, if existing, will be returned.
      *
      * @param int[] $objectIDs
-     * @return  DatabaseObject[]
+     * @return array<int, ?TDatabaseObject>
      */
     public function getObjects(array $objectIDs);
 
@@ -62,6 +66,7 @@ public function getObjects(array $objectIDs);
      * Removes the object with the given id from the runtime cache if it has already been loaded.
      *
      * @param int $objectID
+     * @return void
      */
     public function removeObject($objectID);
 
@@ -69,6 +74,7 @@ public function removeObject($objectID);
      * Removes the objects with the given ids from the runtime cache if they have already been loaded.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function removeObjects(array $objectIDs);
 }
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/MediaRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/MediaRuntimeCache.class.php
index d19835d5ed2..fc6fc9cff2b 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/MediaRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/MediaRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  Media[]         getCachedObjects()
- * @method  Media|null      getObject($objectID)
- * @method  Media[]         getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<Media, MediaList>
  */
 class MediaRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/UserProfileRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/UserProfileRuntimeCache.class.php
index 6117539a7ff..72c8dc1583b 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/UserProfileRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/UserProfileRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  (UserProfile|null)[]    getCachedObjects()
- * @method  UserProfile|null getObject($objectID)
- * @method  (UserProfile|null)[]    getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<UserProfile, UserProfileList>
  */
 class UserProfileRuntimeCache extends AbstractRuntimeCache
 {
@@ -28,8 +26,8 @@ class UserProfileRuntimeCache extends AbstractRuntimeCache
      * Adds a user profile to the cache. This is an internal method that should
      * not be used on a regular basis.
      *
-     * @param UserProfile $profile
-     * @since       3.1
+     * @return void
+     * @since 3.1
      */
     public function addUserProfile(UserProfile $profile)
     {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/UserRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/UserRuntimeCache.class.php
index 6e95fe4be79..44ca64e2035 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/UserRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/UserRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  (User|null)[]      getCachedObjects()
- * @method  ?User   getObject($objectID)
- * @method  (User|null)[]      getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<User, UserList>
  */
 class UserRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleContentRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleContentRuntimeCache.class.php
index c49b9ec5062..92cb8f840a4 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleContentRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleContentRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method  ViewableArticleContent[]        getCachedObjects()
- * @method  ViewableArticleContent|null     getObject($objectID)
- * @method  ViewableArticleContent[]        getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<ViewableArticleContent, ViewableArticleContentList>
  */
 class ViewableArticleContentRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleRuntimeCache.class.php
index 1cfde354f76..d3fd23bd66e 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/ViewableArticleRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ViewableArticle[]       getCachedObjects()
- * @method  ViewableArticle|null    getObject($objectID)
- * @method  ViewableArticle[]       getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<ViewableArticle, ViewableArticleList>
  */
 class ViewableArticleRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentResponseRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentResponseRuntimeCache.class.php
index 85b49b424d6..0cde5dd7ae5 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentResponseRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentResponseRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.5
  *
- * @method  (ViewableCommentResponse|null)[]   getCachedObjects()
- * @method  ?ViewableCommentResponse     getObject($objectID)
- * @method  (ViewableCommentResponse|null)[]   getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<ViewableCommentResponse, ViewableCommentResponseList>
  */
 class ViewableCommentResponseRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentRuntimeCache.class.php
index d522973f502..9c1f3897c6b 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/ViewableCommentRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.5
  *
- * @method  (ViewableComment|null)[]   getCachedObjects()
- * @method  ViewableComment|null     getObject($objectID)
- * @method  (ViewableComment|null)[]   getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<ViewableComment, ViewableCommentList>
  */
 class ViewableCommentRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/runtime/ViewableMediaRuntimeCache.class.php b/wcfsetup/install/files/lib/system/cache/runtime/ViewableMediaRuntimeCache.class.php
index f53fa6f9fbc..eff8044a7f5 100644
--- a/wcfsetup/install/files/lib/system/cache/runtime/ViewableMediaRuntimeCache.class.php
+++ b/wcfsetup/install/files/lib/system/cache/runtime/ViewableMediaRuntimeCache.class.php
@@ -13,9 +13,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  (ViewableMedia|null)[]         getCachedObjects()
- * @method  ?ViewableMedia      getObject($objectID)
- * @method  (ViewableMedia|null)[]         getObjects(array $objectIDs)
+ * @extends AbstractRuntimeCache<ViewableMedia, ViewableMediaList>
  */
 class ViewableMediaRuntimeCache extends AbstractRuntimeCache
 {
diff --git a/wcfsetup/install/files/lib/system/cache/source/ICacheSource.class.php b/wcfsetup/install/files/lib/system/cache/source/ICacheSource.class.php
index 9c8c3897832..52535eeb8c8 100644
--- a/wcfsetup/install/files/lib/system/cache/source/ICacheSource.class.php
+++ b/wcfsetup/install/files/lib/system/cache/source/ICacheSource.class.php
@@ -16,11 +16,14 @@ interface ICacheSource
      *
      * @param string $cacheName
      * @param bool $useWildcard
+     * @return void
      */
     public function flush($cacheName, $useWildcard);
 
     /**
      * Clears the cache completely.
+     *
+     * @return void
      */
     public function flushAll();
 
@@ -29,7 +32,7 @@ public function flushAll();
      *
      * @param string $cacheName
      * @param int $maxLifetime
-     * @return  mixed
+     * @return mixed
      */
     public function get($cacheName, $maxLifetime);
 
@@ -39,6 +42,7 @@ public function get($cacheName, $maxLifetime);
      * @param string $cacheName
      * @param mixed $value
      * @param int $maxLifetime
+     * @return void
      */
     public function set($cacheName, $value, $maxLifetime);
 }
diff --git a/wcfsetup/install/files/lib/system/captcha/CaptchaQuestionHandler.class.php b/wcfsetup/install/files/lib/system/captcha/CaptchaQuestionHandler.class.php
index fead4200ca8..e5321901d14 100644
--- a/wcfsetup/install/files/lib/system/captcha/CaptchaQuestionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/captcha/CaptchaQuestionHandler.class.php
@@ -21,30 +21,25 @@ final class CaptchaQuestionHandler implements ICaptchaHandler
 {
     /**
      * answer to the captcha question
-     * @var string
      */
-    protected $captchaAnswer = '';
+    private string $captchaAnswer = '';
 
     /**
      * unique identifier of the captcha question
-     * @var string
      */
-    protected $captchaQuestion = '';
+    private string $captchaQuestion = '';
 
     /**
      * captcha question to answer
      */
-    protected CaptchaQuestionEditor $question;
+    private CaptchaQuestionEditor $question;
 
     /**
      * list of available captcha questions
      * @var CaptchaQuestion[]
      */
-    protected $questions = [];
+    private array $questions = [];
 
-    /**
-     * Creates a new instance of CaptchaQuestionHandler.
-     */
     public function __construct()
     {
         $this->questions = CaptchaQuestionCacheBuilder::getInstance()->getData();
@@ -111,7 +106,7 @@ public function reset()
     /**
      * Reads a random captcha question.
      */
-    protected function readCaptchaQuestion()
+    private function readCaptchaQuestion(): void
     {
         $questionID = \array_rand($this->questions);
         $this->question = new CaptchaQuestionEditor($this->questions[$questionID]);
diff --git a/wcfsetup/install/files/lib/system/captcha/ICaptchaHandler.class.php b/wcfsetup/install/files/lib/system/captcha/ICaptchaHandler.class.php
index 44511119ef7..55e92e7fd9d 100644
--- a/wcfsetup/install/files/lib/system/captcha/ICaptchaHandler.class.php
+++ b/wcfsetup/install/files/lib/system/captcha/ICaptchaHandler.class.php
@@ -14,29 +14,35 @@ interface ICaptchaHandler
     /**
      * Returns the form element.
      *
-     * @return  string
+     * @return string
      */
     public function getFormElement();
 
     /**
      * Returns true if this kind of captcha is available.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAvailable();
 
     /**
      * Reads the parameters of the captcha form element.
+     *
+     * @return void
      */
     public function readFormParameters();
 
     /**
      * Resets the captcha after it is no longer needed.
+     *
+     * @return void
      */
     public function reset();
 
     /**
      * Validates the response to the challenge and marks the captcha as done.
+     *
+     * @return void
      */
     public function validate();
 }
diff --git a/wcfsetup/install/files/lib/system/category/CategoryHandler.class.php b/wcfsetup/install/files/lib/system/category/CategoryHandler.class.php
index 17ddfd5c3b0..335082eb668 100644
--- a/wcfsetup/install/files/lib/system/category/CategoryHandler.class.php
+++ b/wcfsetup/install/files/lib/system/category/CategoryHandler.class.php
@@ -46,8 +46,8 @@ class CategoryHandler extends SingletonFactory
      * Returns all category objects with the given object type. If no object
      * type is given, all categories grouped by object type are returned.
      *
-     * @param string $objectType
-     * @return  Category[]|Category[][]
+     * @param ?string $objectType
+     * @return ($objectType is null ? array<string, array<int, Category>> : array<int, Category>)
      */
     public function getCategories($objectType = null)
     {
@@ -157,6 +157,8 @@ protected function init()
 
     /**
      * Reloads the category cache.
+     *
+     * @return void
      */
     public function reloadCache()
     {
diff --git a/wcfsetup/install/files/lib/system/category/CategoryPermissionHandler.class.php b/wcfsetup/install/files/lib/system/category/CategoryPermissionHandler.class.php
index c652fef6281..8200996366e 100644
--- a/wcfsetup/install/files/lib/system/category/CategoryPermissionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/category/CategoryPermissionHandler.class.php
@@ -19,7 +19,10 @@ class CategoryPermissionHandler extends SingletonFactory
 {
     /**
      * cached category acl options
-     * @var array
+     * @var array<int, array{
+     *  group: array<int, array<string, int>>,
+     *  user: array<int, array<string, int>>,
+     * }>
      */
     protected $categoryPermissions = [];
 
@@ -29,7 +32,7 @@ class CategoryPermissionHandler extends SingletonFactory
      *
      * @param Category $category
      * @param User $user
-     * @return  int[]
+     * @return array<string, int>
      */
     public function getPermissions(Category $category, ?User $user = null)
     {
@@ -39,24 +42,19 @@ public function getPermissions(Category $category, ?User $user = null)
 
         $permissions = [];
         if (isset($this->categoryPermissions[$category->categoryID])) {
-            if (isset($this->categoryPermissions[$category->categoryID]['group'])) {
-                foreach ($user->getGroupIDs() as $groupID) {
-                    if (isset($this->categoryPermissions[$category->categoryID]['group'][$groupID])) {
-                        foreach ($this->categoryPermissions[$category->categoryID]['group'][$groupID] as $optionName => $optionValue) {
-                            if (isset($permissions[$optionName])) {
-                                $permissions[$optionName] = $permissions[$optionName] || $optionValue;
-                            } else {
-                                $permissions[$optionName] = $optionValue;
-                            }
+            foreach ($user->getGroupIDs() as $groupID) {
+                if (isset($this->categoryPermissions[$category->categoryID]['group'][$groupID])) {
+                    foreach ($this->categoryPermissions[$category->categoryID]['group'][$groupID] as $optionName => $optionValue) {
+                        if (isset($permissions[$optionName])) {
+                            $permissions[$optionName] = $permissions[$optionName] || $optionValue;
+                        } else {
+                            $permissions[$optionName] = $optionValue;
                         }
                     }
                 }
             }
 
-            if (
-                isset($this->categoryPermissions[$category->categoryID]['user'])
-                && isset($this->categoryPermissions[$category->categoryID]['user'][$user->userID])
-            ) {
+            if (isset($this->categoryPermissions[$category->categoryID]['user'][$user->userID])) {
                 foreach ($this->categoryPermissions[$category->categoryID]['user'][$user->userID] as $optionName => $optionValue) {
                     $permissions[$optionName] = $optionValue;
                 }
@@ -76,6 +74,8 @@ protected function init()
 
     /**
      * Resets the category permission cache.
+     *
+     * @return void
      */
     public function resetCache()
     {
diff --git a/wcfsetup/install/files/lib/system/category/ICategoryType.class.php b/wcfsetup/install/files/lib/system/category/ICategoryType.class.php
index 442cb2470b2..c0bbe9c9a7a 100644
--- a/wcfsetup/install/files/lib/system/category/ICategoryType.class.php
+++ b/wcfsetup/install/files/lib/system/category/ICategoryType.class.php
@@ -16,15 +16,14 @@ interface ICategoryType
     /**
      * Is called right after the given category is deleted.
      *
-     * @param CategoryEditor $categoryEditor
+     * @return void
      */
     public function afterDeletion(CategoryEditor $categoryEditor);
 
     /**
      * Is called before the given category is deleted.
      *
-     * @param CategoryEditor $categoryEditor
-     * @since   3.1
+     * @since 3.1
      * @return void
      */
     public function beforeDeletion(CategoryEditor $categoryEditor);
@@ -32,54 +31,46 @@ public function beforeDeletion(CategoryEditor $categoryEditor);
     /**
      * Returns true if the active user can add a category of this type.
      *
-     * @return  bool
+     * @return bool
      */
     public function canAddCategory();
 
     /**
      * Returns true if the active user can delete a category of this type.
      *
-     * @return  bool
+     * @return bool
      */
     public function canDeleteCategory();
 
     /**
      * Returns true if the active user can edit a category of this type.
      *
-     * @return  bool
+     * @return bool
      */
     public function canEditCategory();
 
     /**
      * Is called after categories were assigned different parent categories.
      *
-     * Array structure:
-     * [
-     *  categoryID => [
-     *      oldParentCategoryID => 1,
-     *      newParentCategoryID => 2
-     *  ],
-     *  categoryID => [
-     *      oldParentCategoryID => null,
-     *      newParentCategoryID => 2
-     *  ],
-     * ]
-     *
-     * @param array $categoryData
+     * @param array<int, array{
+     *  newParentCategoryID: int,
+     *  oldParentCategoryID: ?int,
+     * }> $categoryData
+     * @return void
      */
     public function changedParentCategories(array $categoryData);
 
     /**
      * Returns true if a category of this type may have no empty description.
      *
-     * @return  bool
+     * @return bool
      */
     public function forceDescription();
 
     /**
      * Returns abbreviation of the application this category type belongs to.
      *
-     * @return  string
+     * @return string
      */
     public function getApplication();
 
@@ -88,7 +79,7 @@ public function getApplication();
      * name for categories of this type or `null` if no such object type exists.
      *
      * @param string $definitionName
-     * @return  string|null
+     * @return ?string
      */
     public function getObjectTypeName($definitionName);
 
@@ -96,14 +87,14 @@ public function getObjectTypeName($definitionName);
      * Returns the language variable category for the description language
      * variables of categories of this type.
      *
-     * @return  string
+     * @return string
      */
     public function getDescriptionLangVarCategory();
 
     /**
      * Returns the prefix used for language variables of i18n values.
      *
-     * @return  string
+     * @return string
      */
     public function getI18nLangVarPrefix();
 
@@ -118,7 +109,7 @@ public function getI18nLangVarPrefix();
      *
      * @param string $name
      * @param bool $optional
-     * @return  string
+     * @return string
      */
     public function getLanguageVariable($name, $optional = false);
 
@@ -126,7 +117,7 @@ public function getLanguageVariable($name, $optional = false);
      * Returns the maximum category nesting level for this type. "-1" means
      * that there is no maximum.
      *
-     * @return  int
+     * @return int
      */
     public function getMaximumNestingLevel();
 
@@ -134,22 +125,22 @@ public function getMaximumNestingLevel();
      * Returns the language variable category for the title language variables
      * of categories of this type.
      *
-     * @return  string
+     * @return string
      */
     public function getTitleLangVarCategory();
 
     /**
      * Returns true if categories of this type have descriptions.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasDescription();
 
     /**
      * Returns `true` if the descriptions of categories of this type support HTML.
      *
-     * @return  bool
-     * @since   5.2
+     * @return bool
+     * @since 5.2
      */
     public function supportsHtmlDescription();
 }
diff --git a/wcfsetup/install/files/lib/system/cli/command/CLICommandHandler.class.php b/wcfsetup/install/files/lib/system/cli/command/CLICommandHandler.class.php
index 599adfb8db0..e95bf6452f1 100644
--- a/wcfsetup/install/files/lib/system/cli/command/CLICommandHandler.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/CLICommandHandler.class.php
@@ -19,11 +19,12 @@ class CLICommandHandler
 {
     /**
      * list of all available commands
-     * @var ICLICommand[]
+     * @var array<string, ICLICommand>
      */
     private static $commands = [];
 
     /**
+     * @return array<string, ICLICommand>
      * @deprecated 6.0 This method is unused and of questionable value.
      */
     public static function getCommands()
@@ -60,8 +61,8 @@ public static function getCommands()
      * Returns a command by the given line.
      *
      * @param string $line
-     * @return  ICLICommand
-     * @throws  IllegalLinkException
+     * @return ICLICommand
+     * @throws IllegalLinkException
      */
     public static function getCommand($line)
     {
@@ -78,8 +79,8 @@ public static function getCommand($line)
      * Returns a command by the given line.
      *
      * @param string $line
-     * @return  string
-     * @throws  IllegalLinkException
+     * @return string
+     * @throws IllegalLinkException
      */
     public static function getCommandName($line)
     {
@@ -96,7 +97,7 @@ public static function getCommandName($line)
      * Returns the parameter list of the given line.
      *
      * @param string $line
-     * @return  string[]
+     * @return string[]
      */
     public static function getParameters($line)
     {
diff --git a/wcfsetup/install/files/lib/system/cli/command/IArgumentedCLICommand.class.php b/wcfsetup/install/files/lib/system/cli/command/IArgumentedCLICommand.class.php
index 65fd148b9f6..e1349869c7e 100644
--- a/wcfsetup/install/files/lib/system/cli/command/IArgumentedCLICommand.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/IArgumentedCLICommand.class.php
@@ -7,5 +7,8 @@
  */
 interface IArgumentedCLICommand extends ICLICommand
 {
+    /**
+     * @return string
+     */
     public function getUsage();
 }
diff --git a/wcfsetup/install/files/lib/system/cli/command/ICLICommand.class.php b/wcfsetup/install/files/lib/system/cli/command/ICLICommand.class.php
index f025fe54fef..b3f24ace4b4 100644
--- a/wcfsetup/install/files/lib/system/cli/command/ICLICommand.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/ICLICommand.class.php
@@ -14,14 +14,15 @@ interface ICLICommand
     /**
      * Executes the command.
      *
-     * @param array $parameters
+     * @param mixed[] $parameters
+     * @return void
      */
     public function execute(array $parameters);
 
     /**
      * Returns true if the user is allowed to use this command.
      *
-     * @return  bool
+     * @return bool
      */
     public function canAccess();
 }
diff --git a/wcfsetup/install/files/lib/system/cli/command/ImportCLICommand.class.php b/wcfsetup/install/files/lib/system/cli/command/ImportCLICommand.class.php
index c37deb78bc5..03fd4bff359 100644
--- a/wcfsetup/install/files/lib/system/cli/command/ImportCLICommand.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/ImportCLICommand.class.php
@@ -93,7 +93,7 @@ class ImportCLICommand implements ICLICommand
 
     /**
      * list of supported data types
-     * @var array
+     * @var array<string, array<string, string>>
      */
     protected $supportedData = [];
 
@@ -204,6 +204,8 @@ public function execute(array $parameters)
 
     /**
      * Reads the database connection.
+     *
+     * @return void
      */
     protected function readDatabaseConnection()
     {
@@ -275,6 +277,8 @@ protected function readDatabaseConnection()
 
     /**
      * Reads the selected exporter.
+     *
+     * @return void
      */
     protected function readExporter()
     {
@@ -325,6 +329,8 @@ protected function readExporter()
 
     /**
      * Reads the path to the file system.
+     *
+     * @return void
      */
     protected function readFileSystemPath()
     {
@@ -355,6 +361,8 @@ protected function readFileSystemPath()
 
     /**
      * Reads the selected data which will be imported.
+     *
+     * @return void
      */
     protected function readSelectedData()
     {
@@ -511,6 +519,8 @@ protected function readSelectedData()
 
     /**
      * Reads the user merge mode.
+     *
+     * @return void
      */
     protected function readUserMergeMode()
     {
diff --git a/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php b/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
index 4d81c9c4035..07a0351e7ff 100644
--- a/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
@@ -197,6 +197,9 @@ public function execute(array $parameters)
 
     /**
      * Contains the logic of the parent controller process in multithreading mode.
+     *
+     * @param int $threads
+     * @return void
      */
     protected function spawnController(IWorker $worker, $threads)
     {
@@ -401,7 +404,7 @@ protected function spawnController(IWorker $worker, $threads)
     /**
      * Returns an array with the list of all available workers.
      *
-     * @return  array
+     * @return list<array{0: string, 1: string}>
      */
     public function generateList()
     {
@@ -449,7 +452,7 @@ public function generateList()
     }
 
     /**
-     * @inheritDoc
+     * @return string
      */
     public function getUsage()
     {
diff --git a/wcfsetup/install/files/lib/system/clipboard/ClipboardEditorItem.class.php b/wcfsetup/install/files/lib/system/clipboard/ClipboardEditorItem.class.php
index 58a7498f653..f7aef4908d2 100644
--- a/wcfsetup/install/files/lib/system/clipboard/ClipboardEditorItem.class.php
+++ b/wcfsetup/install/files/lib/system/clipboard/ClipboardEditorItem.class.php
@@ -15,44 +15,40 @@ final class ClipboardEditorItem
 {
     /**
      * internal data
-     * @var array
+     * @var mixed[]
      */
-    protected $internalData = [];
+    private array $internalData = [];
 
     /**
      * item name
-     * @var string
      */
-    protected $name = '';
+    private string $name = '';
 
     /**
      * list of parameters passed to ClipboardProxyAction
-     * @var array
+     * @var mixed[]
      */
-    protected $parameters = [];
+    private array $parameters = [];
 
     /**
      * redirect url
-     * @var string
      */
-    protected $url = '';
+    private string $url = '';
 
     /**
      * Returns internal data.
      *
-     * @return  array
+     * @return mixed[]
      */
-    public function getInternalData()
+    public function getInternalData(): array
     {
         return $this->internalData;
     }
 
     /**
      * Returns item name.
-     *
-     * @return  string
      */
-    public function getName()
+    public function getName(): string
     {
         return $this->name;
     }
@@ -60,19 +56,17 @@ public function getName()
     /**
      * Returns parameters passed to ClipboardProxyAction.
      *
-     * @return  array
+     * @return mixed[]
      */
-    public function getParameters()
+    public function getParameters(): array
     {
         return $this->parameters;
     }
 
     /**
      * Returns redirect url.
-     *
-     * @return  string
      */
-    public function getURL()
+    public function getURL(): string
     {
         return $this->url;
     }
@@ -80,11 +74,9 @@ public function getURL()
     /**
      * Adds internal data, values will be left untouched by clipboard API.
      *
-     * @param string $name
-     * @param mixed $value
-     * @throws  SystemException
+     * @throws SystemException
      */
-    public function addInternalData($name, $value)
+    public function addInternalData(string $name, mixed $value): void
     {
         if (!\preg_match('~^[a-zA-Z]+$~', $name)) {
             throw new SystemException("internal data name '" . $name . "' is invalid");
@@ -100,11 +92,9 @@ public function addInternalData($name, $value)
     /**
      * Adds an parameter passed to ClipboardProxyAction.
      *
-     * @param string $name
-     * @param mixed $value
-     * @throws  SystemException
+     * @throws SystemException
      */
-    public function addParameter($name, $value)
+    public function addParameter(string $name, mixed $value): void
     {
         if (!\preg_match('~^[a-zA-Z]+$~', $name)) {
             throw new SystemException("parameter name '" . $name . "' is invalid");
@@ -120,10 +110,9 @@ public function addParameter($name, $value)
     /**
      * Sets item name.
      *
-     * @param string $name
-     * @throws  SystemException
+     * @throws SystemException
      */
-    public function setName($name)
+    public function setName(string $name): void
     {
         if (!\preg_match('~^[a-zA-Z0-9\.-]+$~', $name)) {
             throw new SystemException("item name '" . $name . "' is invalid");
@@ -134,20 +123,16 @@ public function setName($name)
 
     /**
      * Sets redirect url, session id will be appended.
-     *
-     * @param string $url
      */
-    public function setURL($url)
+    public function setURL(string $url): void
     {
         $this->url = $url;
     }
 
     /**
      * Returns number of affected items.
-     *
-     * @return  int
      */
-    public function getCount()
+    public function getCount(): int
     {
         if (isset($this->parameters['objectIDs'])) {
             return \count($this->parameters['objectIDs']);
diff --git a/wcfsetup/install/files/lib/system/clipboard/ClipboardHandler.class.php b/wcfsetup/install/files/lib/system/clipboard/ClipboardHandler.class.php
index 4dda5691a3c..68785836169 100644
--- a/wcfsetup/install/files/lib/system/clipboard/ClipboardHandler.class.php
+++ b/wcfsetup/install/files/lib/system/clipboard/ClipboardHandler.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\clipboard;
 
+use wcf\data\clipboard\action\ClipboardAction;
 use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectType;
@@ -26,25 +27,28 @@ class ClipboardHandler extends SingletonFactory
 {
     /**
      * cached list of actions
-     * @var array
+     * @var array<int, ClipboardAction>
      */
     protected $actionCache;
 
     /**
      * cached list of clipboard item types
-     * @var mixed[][]
+     * @var array{
+     *  objectTypes: array<int, ObjectType>,
+     *  objectTypeNames: array<string, int>,
+     * }
      */
     protected $cache;
 
     /**
      * list of marked items
-     * @var DatabaseObject[][]
+     * @var array<string, DatabaseObject[]>
      */
     protected $markedItems;
 
     /**
      * cached list of page actions
-     * @var array
+     * @var array<string, int[]>
      */
     protected $pageCache;
 
@@ -80,6 +84,8 @@ protected function init()
 
     /**
      * Loads action cache.
+     *
+     * @return void
      */
     protected function loadActionCache()
     {
@@ -93,8 +99,9 @@ protected function loadActionCache()
     /**
      * Marks objects as marked.
      *
-     * @param array $objectIDs
+     * @param int[] $objectIDs
      * @param int $objectTypeID
+     * @return void
      */
     public function mark(array $objectIDs, $objectTypeID)
     {
@@ -117,8 +124,9 @@ public function mark(array $objectIDs, $objectTypeID)
     /**
      * Removes an object marking.
      *
-     * @param array $objectIDs
+     * @param int[] $objectIDs
      * @param int $objectTypeID
+     * @return void
      */
     public function unmark(array $objectIDs, $objectTypeID)
     {
@@ -141,6 +149,7 @@ public function unmark(array $objectIDs, $objectTypeID)
      * Unmarks all items of given type.
      *
      * @param int $objectTypeID
+     * @return void
      */
     public function unmarkAll($objectTypeID)
     {
@@ -159,7 +168,7 @@ public function unmarkAll($objectTypeID)
      * clipboard object type exists.
      *
      * @param string $typeName
-     * @return  int|null
+     * @return ?int
      */
     public function getObjectTypeID($typeName)
     {
@@ -171,7 +180,7 @@ public function getObjectTypeID($typeName)
      * clipboard object type exists.
      *
      * @param int $objectTypeID
-     * @return  ObjectType|null
+     * @return ?ObjectType
      */
     public function getObjectType($objectTypeID)
     {
@@ -183,7 +192,7 @@ public function getObjectType($objectTypeID)
      * clipboard object type exists.
      *
      * @param string $objectType
-     * @return  int|null
+     * @return ?int
      */
     public function getObjectTypeByName($objectType)
     {
@@ -200,7 +209,8 @@ public function getObjectTypeByName($objectType)
      * Loads a list of marked items grouped by type name.
      *
      * @param int $objectTypeID
-     * @throws  SystemException
+     * @return void
+     * @throws SystemException
      */
     protected function loadMarkedItems($objectTypeID = null)
     {
@@ -258,7 +268,7 @@ protected function loadMarkedItems($objectTypeID = null)
 
         // read objects
         foreach ($data as $objectType => $objectData) {
-            /** @var DatabaseObjectList $objectList */
+            /** @var DatabaseObjectList<DatabaseObject> $objectList */
             $objectList = new $objectData['className']();
             $objectList->getConditionBuilder()->add(
                 $objectList->getDatabaseTableAlias() . "." . $objectList->getDatabaseTableIndexName() . " IN (?)",
@@ -293,8 +303,8 @@ protected function loadMarkedItems($objectTypeID = null)
     /**
      * Loads a list of marked items grouped by type name.
      *
-     * @param int $objectTypeID
-     * @return  array
+     * @param ?int $objectTypeID
+     * @return DatabaseObject[]|array<string, DatabaseObject[]>
      */
     public function getMarkedItems($objectTypeID = null)
     {
@@ -327,7 +337,11 @@ public function isMarked(int $objectTypeID, int $objectID): bool
      *
      * @param string|string[] $page
      * @param int $pageObjectID
-     * @return  array|null
+     * @return ?array<string, array{
+     *  label: string,
+     *  items: array<int, ClipboardEditorItem>,
+     *  reloadPageOnSuccess: string[],
+     * }>
      * @throws  ImplementationException
      */
     public function getEditorItems($page, $pageObjectID)
@@ -423,6 +437,7 @@ public function getEditorItems($page, $pageObjectID)
      * Removes items from clipboard.
      *
      * @param int $typeID
+     * @return void
      */
     public function removeItems($typeID = null)
     {
diff --git a/wcfsetup/install/files/lib/system/clipboard/action/IClipboardAction.class.php b/wcfsetup/install/files/lib/system/clipboard/action/IClipboardAction.class.php
index 1fa66a70cc9..509ab064e92 100644
--- a/wcfsetup/install/files/lib/system/clipboard/action/IClipboardAction.class.php
+++ b/wcfsetup/install/files/lib/system/clipboard/action/IClipboardAction.class.php
@@ -28,22 +28,22 @@ public function getTypeName();
      *
      * @param DatabaseObject[] $objects
      * @param ClipboardAction $action
-     * @return  ClipboardEditorItem|null
+     * @return ?ClipboardEditorItem
      */
     public function execute(array $objects, ClipboardAction $action);
 
     /**
      * Returns action class name.
      *
-     * @return  string
+     * @return string
      */
     public function getClassName();
 
     /**
      * Returns label for item editor.
      *
-     * @param array $objects
-     * @return  string
+     * @param DatabaseObject[] $objects
+     * @return string
      */
     public function getEditorLabel(array $objects);
 
@@ -51,8 +51,8 @@ public function getEditorLabel(array $objects);
      * Returns the list of action names that should trigger a page reload once they
      * have been executed.
      *
-     * @return      string[]
-     * @since       5.2
+     * @return string[]
+     * @since 5.2
      */
     public function getReloadPageOnSuccess();
 }
diff --git a/wcfsetup/install/files/lib/system/comment/CommentDataHandler.class.php b/wcfsetup/install/files/lib/system/comment/CommentDataHandler.class.php
index 5a0b6f644db..7c16ddbe4a9 100644
--- a/wcfsetup/install/files/lib/system/comment/CommentDataHandler.class.php
+++ b/wcfsetup/install/files/lib/system/comment/CommentDataHandler.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\comment;
 
+use wcf\data\comment\Comment;
+use wcf\data\user\UserProfile;
 use wcf\system\cache\runtime\CommentRuntimeCache;
 use wcf\system\cache\runtime\UserProfileRuntimeCache;
 use wcf\system\SingletonFactory;
@@ -17,7 +19,8 @@
 class CommentDataHandler extends SingletonFactory
 {
     /**
-     * @inheritDoc
+     * @param int $commentID
+     * @return void
      */
     public function cacheCommentID($commentID)
     {
@@ -25,7 +28,8 @@ public function cacheCommentID($commentID)
     }
 
     /**
-     * @inheritDoc
+     * @param int $userID
+     * @return void
      */
     public function cacheUserID($userID)
     {
@@ -33,7 +37,8 @@ public function cacheUserID($userID)
     }
 
     /**
-     * @inheritDoc
+     * @param int $commentID
+     * @return ?Comment
      */
     public function getComment($commentID)
     {
@@ -41,7 +46,8 @@ public function getComment($commentID)
     }
 
     /**
-     * @inheritDoc
+     * @param int $userID
+     * @return ?UserProfile
      */
     public function getUser($userID)
     {
diff --git a/wcfsetup/install/files/lib/system/comment/CommentHandler.class.php b/wcfsetup/install/files/lib/system/comment/CommentHandler.class.php
index dbd2b4a7341..26ebd425b23 100644
--- a/wcfsetup/install/files/lib/system/comment/CommentHandler.class.php
+++ b/wcfsetup/install/files/lib/system/comment/CommentHandler.class.php
@@ -34,8 +34,10 @@
 class CommentHandler extends SingletonFactory
 {
     /**
-     * cached object types
-     * @var mixed[][]
+     * @var array{
+     *  objectTypes: array<int, ObjectType>,
+     *  objectTypeIDs: array<string, int>,
+     * }
      */
     protected $cache;
 
@@ -61,7 +63,7 @@ protected function init()
      * such object type exists.
      *
      * @param string $objectType
-     * @return  int|null
+     * @return ?int
      */
     public function getObjectTypeID($objectType)
     {
@@ -73,7 +75,7 @@ public function getObjectTypeID($objectType)
      * object type exists.
      *
      * @param int $objectTypeID
-     * @return  ObjectType|null
+     * @return ?ObjectType
      */
     public function getObjectType($objectTypeID)
     {
@@ -84,8 +86,8 @@ public function getObjectType($objectTypeID)
      * Returns comment manager object for given object type.
      *
      * @param string $objectType
-     * @return  ICommentManager
-     * @throws  SystemException
+     * @return ICommentManager
+     * @throws SystemException
      */
     public function getCommentManager($objectType)
     {
@@ -123,7 +125,7 @@ public function getCommentManagerByID(int $objectTypeID): ICommentManager
      * @param int $objectTypeID
      * @param int $objectID
      * @param bool $readObjects
-     * @return  StructuredCommentList
+     * @return StructuredCommentList
      */
     public function getCommentList(ICommentManager $commentManager, $objectTypeID, $objectID, $readObjects = true)
     {
@@ -140,6 +142,7 @@ public function getCommentList(ICommentManager $commentManager, $objectTypeID, $
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public function deleteObjects($objectType, array $objectIDs)
     {
@@ -219,7 +222,8 @@ public function deleteObjects($objectType, array $objectIDs)
     /**
      * Enforces the flood control.
      *
-     * @throws      NamedUserException      if flood control is exceeded
+     * @return void
+     * @throws NamedUserException if flood control is exceeded
      */
     public static function enforceFloodControl()
     {
@@ -244,8 +248,9 @@ public static function enforceFloodControl()
      * @param string $objectType comment object type name
      * @param int[] $objectIDs ids of the objects whose comment-related notifications will be marked as confirmed
      * @param int $time only notifications older than the given timestamp will be marked as confirmed
-     * @throws  \InvalidArgumentException   if invalid comment object type name is given
-     * @since   5.2
+     * @return void
+     * @throws \InvalidArgumentException if invalid comment object type name is given
+     * @since 5.2
      */
     public function markNotificationsAsConfirmed($objectType, array $objectIDs, $time = TIME_NOW)
     {
@@ -475,8 +480,9 @@ public function markNotificationsAsConfirmed($objectType, array $objectIDs, $tim
      *
      * @param string $objectType comment object type name
      * @param StructuredComment[] $comments comments whose notifications will be marked as read
-     * @throws  \InvalidArgumentException       if invalid comment object type name is given
-     * @since   5.2
+     * @return void
+     * @throws \InvalidArgumentException if invalid comment object type name is given
+     * @since 5.2
      */
     public function markNotificationsAsConfirmedForComments($objectType, array $comments)
     {
@@ -656,9 +662,10 @@ public function markNotificationsAsConfirmedForComments($objectType, array $comm
      *
      * @param string $objectType comment object type name
      * @param (CommentResponse|StructuredCommentResponse)[] $responses comment responses whose notifications will be marked as read
+     * @return void
      *
-     * @throws  \InvalidArgumentException       if invalid comment object type name is given
-     * @since   5.2
+     * @throws \InvalidArgumentException if invalid comment object type name is given
+     * @since 5.2
      */
     public function markNotificationsAsConfirmedForResponses($objectType, array $responses)
     {
@@ -750,7 +757,8 @@ public function markNotificationsAsConfirmedForResponses($objectType, array $res
      * Enforces the censorship.
      *
      * @param string $text
-     * @throws  UserInputException
+     * @return void
+     * @throws UserInputException
      */
     public static function enforceCensorship($text)
     {
diff --git a/wcfsetup/install/files/lib/system/comment/command/DeleteComments.class.php b/wcfsetup/install/files/lib/system/comment/command/DeleteComments.class.php
index b4e0837876f..fd90b56b087 100644
--- a/wcfsetup/install/files/lib/system/comment/command/DeleteComments.class.php
+++ b/wcfsetup/install/files/lib/system/comment/command/DeleteComments.class.php
@@ -24,23 +24,27 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
- *
- * @property-read int[] $commentIDs
- * @property-read Comment[] $comments
  */
 final class DeleteComments
 {
     private readonly ObjectType $objectType;
     private readonly ICommentManager $commentManager;
+    /**
+     * @var int[]
+     */
     private readonly array $commentIDs;
 
+    /**
+     * @param Comment[] $comments
+     */
     public function __construct(
         private readonly array $comments,
         private readonly bool $updateCounters = true,
     ) {
         $this->commentIDs = \array_column($this->comments, 'commentID');
-        $firstComment = \reset($this->comments);
-        \assert($firstComment !== false);
+        $firstCommentID = \array_key_first($this->comments);
+        \assert($firstCommentID !== null);
+        $firstComment = $this->comments[$firstCommentID];
         $this->objectType = CommentHandler::getInstance()->getObjectType($firstComment->objectTypeID);
         $this->commentManager = CommentHandler::getInstance()->getCommentManagerByID($firstComment->objectTypeID);
     }
diff --git a/wcfsetup/install/files/lib/system/comment/manager/AbstractCommentManager.class.php b/wcfsetup/install/files/lib/system/comment/manager/AbstractCommentManager.class.php
index 35c9b8c9138..d92040b9fbb 100644
--- a/wcfsetup/install/files/lib/system/comment/manager/AbstractCommentManager.class.php
+++ b/wcfsetup/install/files/lib/system/comment/manager/AbstractCommentManager.class.php
@@ -263,6 +263,7 @@ public function isContentAuthor($commentOrResponse)
     /**
      * Returns the object ID for the given Comment or CommentResponse.
      *
+     * @param Comment|CommentResponse|DatabaseObjectDecorator<CommentResponse> $commentOrResponse
      * @return int
      */
     final protected function getObjectID($commentOrResponse)
@@ -271,12 +272,13 @@ final protected function getObjectID($commentOrResponse)
             $commentOrResponse instanceof CommentResponse
             || (
                 $commentOrResponse instanceof DatabaseObjectDecorator
+                // @phpstan-ignore instanceof.alwaysTrue
                 && $commentOrResponse->getDecoratedObject() instanceof CommentResponse
             )
         ) {
             return $commentOrResponse->getComment()->objectID;
-        } else {
-            return $commentOrResponse->objectID;
         }
+
+        return $commentOrResponse->objectID;
     }
 }
diff --git a/wcfsetup/install/files/lib/system/comment/manager/ICommentManager.class.php b/wcfsetup/install/files/lib/system/comment/manager/ICommentManager.class.php
index 7b3771f3a89..e9541dbf0b1 100644
--- a/wcfsetup/install/files/lib/system/comment/manager/ICommentManager.class.php
+++ b/wcfsetup/install/files/lib/system/comment/manager/ICommentManager.class.php
@@ -18,7 +18,7 @@ interface ICommentManager
      * Returns true if the current user may add comments or responses.
      *
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function canAdd($objectID);
 
@@ -26,38 +26,35 @@ public function canAdd($objectID);
      * Returns true if a comment requires approval.
      *
      * @param int $objectID
-     * @return      bool
+     * @return bool
      */
     public function canAddWithoutApproval($objectID);
 
     /**
      * Returns true if the current user may edit given comment.
      *
-     * @param Comment $comment
-     * @return  bool
+     * @return bool
      */
     public function canEditComment(Comment $comment);
 
     /**
      * Returns true if the current user may edit given response.
      *
-     * @param CommentResponse $response
-     * @return  bool
+     * @return bool
      */
     public function canEditResponse(CommentResponse $response);
 
     /**
      * Returns true if the current user may delete given comment.
      *
-     * @param Comment $comment
-     * @return  bool
+     * @return bool
      */
     public function canDeleteComment(Comment $comment);
 
     /**
      * Returns true if the current user may delete given response.
      *
-     * @param CommentResponse $response
+     * @return bool
      */
     public function canDeleteResponse(CommentResponse $response);
 
@@ -67,7 +64,7 @@ public function canDeleteResponse(CommentResponse $response);
      *
      * @param int $objectTypeID
      * @param int $objectID
-     * @return  bool
+     * @return bool
      * @deprecated 6.1 use `ICommentPermissionManager::canModerateObject()` instead
      */
     public function canModerate($objectTypeID, $objectID);
@@ -75,7 +72,7 @@ public function canModerate($objectTypeID, $objectID);
     /**
      * Returns the amount of comments per page.
      *
-     * @return  int
+     * @return int
      */
     public function getCommentsPerPage();
 
@@ -84,23 +81,21 @@ public function getCommentsPerPage();
      *
      * @param int $objectTypeID
      * @param int $objectID
-     * @return  string
+     * @return string
      */
     public function getLink($objectTypeID, $objectID);
 
     /**
      * Returns the link to the given comment.
      *
-     * @param Comment $comment
-     * @return  string
+     * @return string
      */
     public function getCommentLink(Comment $comment);
 
     /**
      * Returns the link to the given comment response.
      *
-     * @param CommentResponse $response
-     * @return  string
+     * @return string
      */
     public function getResponseLink(CommentResponse $response);
 
@@ -110,7 +105,7 @@ public function getResponseLink(CommentResponse $response);
      * @param int $objectTypeID
      * @param int $objectID
      * @param bool $isResponse
-     * @return  string
+     * @return string
      */
     public function getTitle($objectTypeID, $objectID, $isResponse = false);
 
@@ -120,7 +115,7 @@ public function getTitle($objectTypeID, $objectID, $isResponse = false);
      *
      * @param int $objectID
      * @param bool $validateWritePermission
-     * @return  bool
+     * @return bool
      */
     public function isAccessible($objectID, $validateWritePermission = false);
 
@@ -129,25 +124,28 @@ public function isAccessible($objectID, $validateWritePermission = false);
      *
      * @param int $objectID
      * @param int $value
+     * @return void
      */
     public function updateCounter($objectID, $value);
 
     /**
      * Returns true if this comment type supports likes.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsLike();
 
     /**
      * Returns true if this comment type supports reports.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsReport();
 
     /**
      * Sets the list of disallowed bbcodes.
+     *
+     * @return void
      */
     public function setDisallowedBBCodes();
 
@@ -156,7 +154,7 @@ public function setDisallowedBBCodes();
      * the content's author.
      *
      * @param Comment|CommentResponse $commentOrResponse
-     * @return  bool
+     * @return bool
      */
     public function isContentAuthor($commentOrResponse);
 }
diff --git a/wcfsetup/install/files/lib/system/comment/response/command/DeleteResponses.class.php b/wcfsetup/install/files/lib/system/comment/response/command/DeleteResponses.class.php
index 23adf99c7d7..be4aee65637 100644
--- a/wcfsetup/install/files/lib/system/comment/response/command/DeleteResponses.class.php
+++ b/wcfsetup/install/files/lib/system/comment/response/command/DeleteResponses.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\comment\response\command;
 
+use wcf\data\comment\Comment;
 use wcf\data\comment\CommentEditor;
 use wcf\data\comment\CommentList;
 use wcf\data\comment\response\CommentResponse;
@@ -24,24 +25,28 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
- *
- * @property-read int[] $responseIDs
- * @property-read CommentResponse[] $responses
  */
 final class DeleteResponses
 {
     private readonly ObjectType $objectType;
     private readonly ICommentManager $commentManager;
 
+    /**
+     * @var int[]
+     */
     private readonly array $responseIDs;
 
+    /**
+     * @param CommentResponse[] $responses
+     */
     public function __construct(
         private readonly array $responses,
         private readonly bool $updateCounters = true,
     ) {
         $this->responseIDs = \array_column($this->responses, 'responseID');
-        $firstResponse = \reset($this->responses);
-        \assert($firstResponse !== false);
+        $firstResponseKey = \array_key_first($this->responses);
+        \assert($firstResponseKey !== null);
+        $firstResponse = $this->responses[$firstResponseKey];
         $this->objectType = CommentHandler::getInstance()->getObjectType($firstResponse->getComment()->objectTypeID);
         $this->commentManager = CommentHandler::getInstance()->getCommentManagerByID($firstResponse->getComment()->objectTypeID);
     }
@@ -124,6 +129,7 @@ private function updateCounters(): void
         $commentList = new CommentList();
         $commentList->setObjectIDs(\array_unique($commentIDs));
         $commentList->readObjects();
+        ///** @var array<int, Comment> */
         $comments = $commentList->getObjects();
 
         foreach ($comments as $comment) {
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractCondition.class.php
index 8f8be205e93..bcfe0ce56ac 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractCondition.class.php
@@ -11,7 +11,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method ?array getData()
+ * @method ?mixed[] getData()
  */
 abstract class AbstractCondition extends AbstractObjectTypeProcessor implements ICondition
 {
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractIntegerCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractIntegerCondition.class.php
index e5986151f6f..a52b6dcdf1a 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractIntegerCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractIntegerCondition.class.php
@@ -255,6 +255,7 @@ public function validate()
     /**
      * Checks if the values for `greaterThan` and `lessThan` are conflicting.
      *
+     * @return void
      * @throws  UserInputException      if values for `greaterThan` and `lessThan` are conflicting
      * @since   3.0
      */
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php
index 8650f9dbbc5..a70ce0b2098 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractMultiSelectCondition.class.php
@@ -18,7 +18,8 @@ abstract class AbstractMultiSelectCondition extends AbstractSelectCondition
 {
     /**
      * selected values
-     * @var array
+     * @var mixed[]
+     * @phpstan-ignore property.phpDocType
      */
     protected $fieldValue = [];
 
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractObjectTextPropertyCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractObjectTextPropertyCondition.class.php
index f95adc05780..5ae68ec229e 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractObjectTextPropertyCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractObjectTextPropertyCondition.class.php
@@ -15,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @implements IObjectListCondition<DatabaseObjectList<DatabaseObject>>
  */
 abstract class AbstractObjectTextPropertyCondition extends AbstractTextCondition implements
     IObjectCondition,
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractSelectCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractSelectCondition.class.php
index b5fa0656a6f..2871da6e0b0 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractSelectCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractSelectCondition.class.php
@@ -110,6 +110,8 @@ protected function getOptionCode($value, $label)
 
     /**
      * Returns the selectable options.
+     *
+     * @return array<string|int, string|mixed[]>
      */
     abstract protected function getOptions();
 
diff --git a/wcfsetup/install/files/lib/system/condition/AbstractTimestampCondition.class.php b/wcfsetup/install/files/lib/system/condition/AbstractTimestampCondition.class.php
index 26821d33539..f39b374a686 100644
--- a/wcfsetup/install/files/lib/system/condition/AbstractTimestampCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/AbstractTimestampCondition.class.php
@@ -17,6 +17,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @implements IObjectListCondition<DatabaseObjectList<DatabaseObject>>
  */
 abstract class AbstractTimestampCondition extends AbstractSingleFieldCondition implements
     IObjectCondition,
@@ -56,7 +58,6 @@ public function addObjectListCondition(DatabaseObjectList $objectList, array $co
             throw new InvalidObjectArgument($objectList, $className, 'Object list');
         }
 
-        // @phpstan-ignore property.notFound
         if ($this->object->ignoreZeroTime) {
             $objectList->getConditionBuilder()->add(
                 $objectList->getDatabaseTableAlias() . '.' . $this->getPropertyName() . ' <> ?',
diff --git a/wcfsetup/install/files/lib/system/condition/ConditionHandler.class.php b/wcfsetup/install/files/lib/system/condition/ConditionHandler.class.php
index 495aaf4d83a..e4d17cbc09b 100644
--- a/wcfsetup/install/files/lib/system/condition/ConditionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/condition/ConditionHandler.class.php
@@ -23,7 +23,7 @@ class ConditionHandler extends SingletonFactory
     /**
      * list of available conditions grouped by the id of the related condition
      * object type definition
-     * @var array
+     * @var array<int, array<int, mixed[]>>
      */
     protected $conditions = [];
 
@@ -33,6 +33,7 @@ class ConditionHandler extends SingletonFactory
      *
      * @param int $objectID
      * @param ObjectType[] $conditionObjectTypes
+     * @return void
      */
     public function createConditions($objectID, array $conditionObjectTypes)
     {
@@ -56,7 +57,8 @@ public function createConditions($objectID, array $conditionObjectTypes)
      *
      * @param string $definitionName
      * @param int[] $objectIDs
-     * @throws  SystemException
+     * @return void
+     * @throws SystemException
      */
     public function deleteConditions($definitionName, array $objectIDs)
     {
@@ -96,8 +98,8 @@ public function deleteConditions($definitionName, array $objectIDs)
      *
      * @param string $definitionName
      * @param int $objectID
-     * @return  Condition[]
-     * @throws  SystemException
+     * @return Condition[]
+     * @throws SystemException
      */
     public function getConditions($definitionName, $objectID)
     {
@@ -126,6 +128,7 @@ public function getConditions($definitionName, $objectID)
      * @param int $objectID
      * @param Condition[] $oldConditions
      * @param ObjectType[] $conditionObjectTypes
+     * @return void
      */
     public function updateConditions($objectID, array $oldConditions, array $conditionObjectTypes)
     {
diff --git a/wcfsetup/install/files/lib/system/condition/ICondition.class.php b/wcfsetup/install/files/lib/system/condition/ICondition.class.php
index 1cbf3f82130..d1418d6889f 100644
--- a/wcfsetup/install/files/lib/system/condition/ICondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/ICondition.class.php
@@ -18,24 +18,28 @@ interface ICondition extends IDatabaseObjectProcessor
      * Returns the data saved with the condition used to check if the condition
      * is fulfilled. If null is returned, there is no condition to be created.
      *
-     * @return ?array
+     * @return ?mixed[]
      */
     public function getData();
 
     /**
      * Returns the output for setting up the condition.
      *
-     * @return  string
+     * @return string
      */
     public function getHTML();
 
     /**
      * Reads the form parameters of the condition.
+     *
+     * @return void
      */
     public function readFormParameters();
 
     /**
      * Resets the internally stored condition data.
+     *
+     * @return void
      */
     public function reset();
 
@@ -43,12 +47,14 @@ public function reset();
      * Extracts all needed data from the given condition to pre-fill the output
      * for editing the given condition.
      *
-     * @param Condition $condition
+     * @return void
      */
     public function setData(Condition $condition);
 
     /**
      * Validates the read condition data.
+     *
+     * @return void
      */
     public function validate();
 }
diff --git a/wcfsetup/install/files/lib/system/condition/IContentCondition.class.php b/wcfsetup/install/files/lib/system/condition/IContentCondition.class.php
index ce64676e701..3d070ce3c57 100644
--- a/wcfsetup/install/files/lib/system/condition/IContentCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/IContentCondition.class.php
@@ -20,7 +20,7 @@ interface IContentCondition extends ICondition
      * like the active user object via WCF::getUser().
      *
      * @param Condition $condition
-     * @return  bool
+     * @return bool
      */
     public function showContent(Condition $condition);
 }
diff --git a/wcfsetup/install/files/lib/system/condition/IObjectCondition.class.php b/wcfsetup/install/files/lib/system/condition/IObjectCondition.class.php
index 684309e9756..9f490e942ec 100644
--- a/wcfsetup/install/files/lib/system/condition/IObjectCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/IObjectCondition.class.php
@@ -19,9 +19,8 @@ interface IObjectCondition extends ICondition
      * Returns true if the given object fulfills the condition specified by
      * the given condition data returned by \wcf\system\condition\ICondition::getData().
      *
-     * @param DatabaseObject $object
-     * @param array $conditionData
-     * @return  bool
+     * @param mixed[] $conditionData
+     * @return bool
      */
     public function checkObject(DatabaseObject $object, array $conditionData);
 }
diff --git a/wcfsetup/install/files/lib/system/condition/IObjectListCondition.class.php b/wcfsetup/install/files/lib/system/condition/IObjectListCondition.class.php
index fc489a41afd..dbd905c0500 100644
--- a/wcfsetup/install/files/lib/system/condition/IObjectListCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/IObjectListCondition.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 interface IObjectListCondition extends ICondition
 {
@@ -19,8 +21,9 @@ interface IObjectListCondition extends ICondition
      * Adds a condition to the given object list based on the given condition
      * data returned by \wcf\system\condition\ICondition::getData().
      *
-     * @param DatabaseObjectList $objectList
-     * @param array $conditionData
+     * @param TDatabaseObjectList $objectList
+     * @param mixed[] $conditionData
+     * @return void
      * @throws  \InvalidArgumentException   if the given object list object is no object of the expected database object list class
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData);
diff --git a/wcfsetup/install/files/lib/system/condition/IUserCondition.class.php b/wcfsetup/install/files/lib/system/condition/IUserCondition.class.php
index 54aaa9e410b..17486a6d3bb 100644
--- a/wcfsetup/install/files/lib/system/condition/IUserCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/IUserCondition.class.php
@@ -19,17 +19,14 @@ interface IUserCondition extends ICondition
      * Adds the condition to the given user list to fetch the users which fulfill
      * the given condition.
      *
-     * @param Condition $condition
-     * @param UserList $userList
+     * @return void
      */
     public function addUserCondition(Condition $condition, UserList $userList);
 
     /**
      * Returns true if the given user fulfills the given condition.
      *
-     * @param Condition $condition
-     * @param User $user
-     * @return  bool
+     * @return bool
      */
     public function checkUser(Condition $condition, User $user);
 }
diff --git a/wcfsetup/install/files/lib/system/condition/TObjectListUserCondition.class.php b/wcfsetup/install/files/lib/system/condition/TObjectListUserCondition.class.php
index 28a5bbdeb38..27caf6d1b6d 100644
--- a/wcfsetup/install/files/lib/system/condition/TObjectListUserCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/TObjectListUserCondition.class.php
@@ -17,7 +17,7 @@
 trait TObjectListUserCondition
 {
     /**
-     * @inheritDoc
+     * @return void
      */
     public function addUserCondition(Condition $condition, UserList $userList)
     {
diff --git a/wcfsetup/install/files/lib/system/condition/UserAvatarCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserAvatarCondition.class.php
index b2bbb724d24..7190060c1c1 100644
--- a/wcfsetup/install/files/lib/system/condition/UserAvatarCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserAvatarCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -15,6 +14,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserAvatarCondition extends AbstractSelectCondition implements
     IContentCondition,
@@ -55,10 +56,6 @@ class UserAvatarCondition extends AbstractSelectCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         switch ($conditionData['userAvatar']) {
             case self::NO_AVATAR:
                 $objectList->getConditionBuilder()->add('user_table.avatarFileID IS NULL');
diff --git a/wcfsetup/install/files/lib/system/condition/UserCoverPhotoCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserCoverPhotoCondition.class.php
index 469545e3884..32bf661dc75 100644
--- a/wcfsetup/install/files/lib/system/condition/UserCoverPhotoCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserCoverPhotoCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -16,6 +15,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserCoverPhotoCondition extends AbstractSelectCondition implements
     IContentCondition,
@@ -51,10 +52,6 @@ class UserCoverPhotoCondition extends AbstractSelectCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         switch ($conditionData['userCoverPhoto']) {
             case self::NO_COVER_PHOTO:
                 $objectList->getConditionBuilder()->add(
diff --git a/wcfsetup/install/files/lib/system/condition/UserEmailCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserEmailCondition.class.php
index b5e4f8ca3eb..ed51f71a987 100644
--- a/wcfsetup/install/files/lib/system/condition/UserEmailCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserEmailCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -15,6 +14,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserEmailCondition extends AbstractTextCondition implements
     IContentCondition,
@@ -38,10 +39,6 @@ class UserEmailCondition extends AbstractTextCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add(
             'user_table.email LIKE ?',
             ['%' . \addcslashes($conditionData['email'], '_%') . '%']
diff --git a/wcfsetup/install/files/lib/system/condition/UserGroupCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserGroupCondition.class.php
index 93cc80e2c82..7663157fd77 100644
--- a/wcfsetup/install/files/lib/system/condition/UserGroupCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserGroupCondition.class.php
@@ -21,6 +21,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @property-read bool $includeguests
+ *
+ * @implements IObjectListCondition<UserList|UsersOnlineList>
  */
 class UserGroupCondition extends AbstractMultipleFieldsCondition implements
     IContentCondition,
@@ -68,10 +70,6 @@ class UserGroupCondition extends AbstractMultipleFieldsCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList) && !($objectList instanceof UsersOnlineList)) {
-            throw new \InvalidArgumentException("Object list is neither an instance of '" . UserList::class . "' nor of '" . UsersOnlineList::class . "', instance of '" . \get_class($objectList) . "' given.");
-        }
-
         $tableName = 'user_table';
         if ($objectList instanceof UsersOnlineList) {
             $tableName = 'session';
@@ -258,6 +256,7 @@ public function setData(Condition $condition)
      * Sets the selectable user groups.
      *
      * @param UserGroup[] $userGroups
+     * @return void
      */
     public function setUserGroups(array $userGroups)
     {
diff --git a/wcfsetup/install/files/lib/system/condition/UserIntegerPropertyCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserIntegerPropertyCondition.class.php
index dfaf1eedeeb..271cb5cbaa4 100644
--- a/wcfsetup/install/files/lib/system/condition/UserIntegerPropertyCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserIntegerPropertyCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -15,6 +14,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserIntegerPropertyCondition extends AbstractIntegerCondition implements
     IContentCondition,
@@ -28,10 +29,6 @@ class UserIntegerPropertyCondition extends AbstractIntegerCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData): void
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['greaterThan'])) {
             /** @noinspection PhpUndefinedFieldInspection */
             $objectList->getConditionBuilder()->add(
diff --git a/wcfsetup/install/files/lib/system/condition/UserLanguageCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserLanguageCondition.class.php
index dbecb9aca26..4785195a082 100644
--- a/wcfsetup/install/files/lib/system/condition/UserLanguageCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserLanguageCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\language\LanguageFactory;
 use wcf\system\WCF;
@@ -18,6 +17,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserLanguageCondition extends AbstractSingleFieldCondition implements
     IContentCondition,
@@ -42,10 +43,6 @@ class UserLanguageCondition extends AbstractSingleFieldCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add('user_table.languageID IN (?)', [$conditionData['languageIDs']]);
     }
 
diff --git a/wcfsetup/install/files/lib/system/condition/UserMultifactorCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserMultifactorCondition.class.php
index 1dcee0277a4..da212448680 100644
--- a/wcfsetup/install/files/lib/system/condition/UserMultifactorCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserMultifactorCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 
@@ -17,6 +16,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.4
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserMultifactorCondition extends AbstractSingleFieldCondition implements
     IContentCondition,
@@ -140,10 +141,6 @@ public function showContent(Condition $condition)
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['multifactorActive'])) {
             $objectList->getConditionBuilder()->add(
                 'user_table.multifactorActive = ?',
diff --git a/wcfsetup/install/files/lib/system/condition/UserOptionsCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserOptionsCondition.class.php
index 23ed4a8f972..f2e913b5ce7 100644
--- a/wcfsetup/install/files/lib/system/condition/UserOptionsCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserOptionsCondition.class.php
@@ -7,7 +7,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\option\ISearchableConditionUserOption;
 use wcf\system\option\user\UserOptionHandler;
 use wcf\system\WCF;
@@ -18,6 +17,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserOptionsCondition extends AbstractMultipleFieldsCondition implements
     IContentCondition,
@@ -49,10 +50,6 @@ public function __construct(DatabaseObject $object)
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $optionValues = $conditionData['optionValues'];
 
         foreach ($this->optionHandler->getCategoryOptions('profile') as $option) {
diff --git a/wcfsetup/install/files/lib/system/condition/UserRegistrationDateCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserRegistrationDateCondition.class.php
index ed2eeae4715..f905edb0f14 100644
--- a/wcfsetup/install/files/lib/system/condition/UserRegistrationDateCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserRegistrationDateCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 
@@ -16,6 +15,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserRegistrationDateCondition extends AbstractSingleFieldCondition implements
     IContentCondition,
@@ -46,10 +47,6 @@ class UserRegistrationDateCondition extends AbstractSingleFieldCondition impleme
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['registrationDateEnd'])) {
             $registrationDateEnd = \DateTime::createFromFormat(
                 'Y-m-d',
diff --git a/wcfsetup/install/files/lib/system/condition/UserRegistrationDateIntervalCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserRegistrationDateIntervalCondition.class.php
index f5a3bce2d6b..0207a4056ed 100644
--- a/wcfsetup/install/files/lib/system/condition/UserRegistrationDateIntervalCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserRegistrationDateIntervalCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 
@@ -17,6 +16,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserRegistrationDateIntervalCondition extends AbstractIntegerCondition implements
     IContentCondition,
@@ -40,10 +41,6 @@ class UserRegistrationDateIntervalCondition extends AbstractIntegerCondition imp
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData): void
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['greaterThan'])) {
             $objectList->getConditionBuilder()->add(
                 'user_table.registrationDate < ?',
diff --git a/wcfsetup/install/files/lib/system/condition/UserSignatureCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserSignatureCondition.class.php
index e88202a17fc..7ecef8d3964 100644
--- a/wcfsetup/install/files/lib/system/condition/UserSignatureCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserSignatureCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -16,6 +15,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserSignatureCondition extends AbstractSelectCondition implements
     IContentCondition,
@@ -51,10 +52,6 @@ class UserSignatureCondition extends AbstractSelectCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         switch ($conditionData['userSignature']) {
             case self::NO_SIGNATURE:
                 $objectList->getConditionBuilder()->add(
diff --git a/wcfsetup/install/files/lib/system/condition/UserStateCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserStateCondition.class.php
index 9202197566f..9553b9ec550 100644
--- a/wcfsetup/install/files/lib/system/condition/UserStateCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserStateCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 
@@ -16,6 +15,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserStateCondition extends AbstractSingleFieldCondition implements
     IContentCondition,
@@ -71,10 +72,6 @@ class UserStateCondition extends AbstractSingleFieldCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['userIsBanned'])) {
             $objectList->getConditionBuilder()->add('user_table.banned = ?', [$conditionData['userIsBanned']]);
         }
diff --git a/wcfsetup/install/files/lib/system/condition/UserTrophyCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserTrophyCondition.class.php
index ecb7e6d79b8..7b566f344fb 100644
--- a/wcfsetup/install/files/lib/system/condition/UserTrophyCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserTrophyCondition.class.php
@@ -9,7 +9,6 @@
 use wcf\data\user\trophy\UserTrophyList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\exception\UserInputException;
 use wcf\system\WCF;
 use wcf\util\ArrayUtil;
@@ -21,6 +20,8 @@
  * @author  Joshua Ruesweg
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserTrophyCondition extends AbstractMultipleFieldsCondition implements
     IContentCondition,
@@ -68,10 +69,6 @@ class UserTrophyCondition extends AbstractMultipleFieldsCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         if (isset($conditionData['userTrophyIDs'])) {
             $objectList->getConditionBuilder()->add(
                 'user_table.userID IN (
@@ -210,7 +207,7 @@ protected function getTrophies()
             $collator = new \Collator(WCF::getLanguage()->getLocale());
             \uasort(
                 $this->trophies,
-                static fn (Trophy $a, Trophy $b) => $collator->compare($a->getTitle(), $b->getTitle())
+                static fn(Trophy $a, Trophy $b) => $collator->compare($a->getTitle(), $b->getTitle())
             );
         }
 
diff --git a/wcfsetup/install/files/lib/system/condition/UserUserIDCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserUserIDCondition.class.php
index 36eef64b4fd..f9df62b3941 100644
--- a/wcfsetup/install/files/lib/system/condition/UserUserIDCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserUserIDCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -15,6 +14,8 @@
  * @author      Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserUserIDCondition extends AbstractSingleFieldCondition implements
     IContentCondition,
@@ -38,10 +39,6 @@ class UserUserIDCondition extends AbstractSingleFieldCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add('user_table.userID = ?', [$conditionData['userID']]);
     }
 
diff --git a/wcfsetup/install/files/lib/system/condition/UserUsernameCondition.class.php b/wcfsetup/install/files/lib/system/condition/UserUsernameCondition.class.php
index 0f1c63037a4..e3312cd261c 100644
--- a/wcfsetup/install/files/lib/system/condition/UserUsernameCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/UserUsernameCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\data\user\UserList;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -15,6 +14,8 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserUsernameCondition extends AbstractTextCondition implements
     IContentCondition,
@@ -38,10 +39,6 @@ class UserUsernameCondition extends AbstractTextCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add(
             'user_table.username LIKE ?',
             ['%' . \addcslashes($conditionData['username'], '_%') . '%']
diff --git a/wcfsetup/install/files/lib/system/condition/article/ArticleCategoryCondition.class.php b/wcfsetup/install/files/lib/system/condition/article/ArticleCategoryCondition.class.php
index df611137dd4..2212e1a0f56 100644
--- a/wcfsetup/install/files/lib/system/condition/article/ArticleCategoryCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/article/ArticleCategoryCondition.class.php
@@ -6,7 +6,6 @@
 use wcf\data\DatabaseObjectList;
 use wcf\system\condition\AbstractMultiCategoryCondition;
 use wcf\system\condition\IObjectListCondition;
-use wcf\system\exception\InvalidObjectArgument;
 
 /**
  * Condition implementation for the category an article belongs to.
@@ -15,6 +14,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @implements IObjectListCondition<ArticleList>
  */
 class ArticleCategoryCondition extends AbstractMultiCategoryCondition implements IObjectListCondition
 {
@@ -38,10 +39,6 @@ class ArticleCategoryCondition extends AbstractMultiCategoryCondition implements
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof ArticleList)) {
-            throw new InvalidObjectArgument($objectList, ArticleList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add('article.categoryID IN (?)', [$conditionData[$this->fieldName]]);
     }
 }
diff --git a/wcfsetup/install/files/lib/system/condition/user/UserLastActivityTimeIntervalDaysCondition.class.php b/wcfsetup/install/files/lib/system/condition/user/UserLastActivityTimeIntervalDaysCondition.class.php
index a4bfca5a823..f30938ee36a 100644
--- a/wcfsetup/install/files/lib/system/condition/user/UserLastActivityTimeIntervalDaysCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/user/UserLastActivityTimeIntervalDaysCondition.class.php
@@ -22,6 +22,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.3
+ *
+ * @implements IObjectListCondition<UserList>
  */
 class UserLastActivityTimeIntervalDaysCondition extends AbstractSingleFieldCondition implements
     IObjectCondition,
@@ -49,11 +51,6 @@ class UserLastActivityTimeIntervalDaysCondition extends AbstractSingleFieldCondi
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserList)) {
-            throw new InvalidObjectArgument($objectList, UserList::class, 'Object list');
-        }
-
-        // @phpstan-ignore property.notFound
         if ($this->object->ignoreZeroTime) {
             $objectList->getConditionBuilder()->add('user_table.lastActivityTime <> ?', [0]);
         }
diff --git a/wcfsetup/install/files/lib/system/condition/user/activity/event/UserActivityEventExcludedObjectTypeCondition.class.php b/wcfsetup/install/files/lib/system/condition/user/activity/event/UserActivityEventExcludedObjectTypeCondition.class.php
index 35d253aa10d..d485b3b247c 100644
--- a/wcfsetup/install/files/lib/system/condition/user/activity/event/UserActivityEventExcludedObjectTypeCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/user/activity/event/UserActivityEventExcludedObjectTypeCondition.class.php
@@ -7,7 +7,6 @@
 use wcf\data\user\activity\event\UserActivityEventList;
 use wcf\system\condition\AbstractMultiSelectCondition;
 use wcf\system\condition\IObjectListCondition;
-use wcf\system\exception\InvalidObjectArgument;
 use wcf\system\WCF;
 
 /**
@@ -17,6 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @implements IObjectListCondition<UserActivityEventList>
  */
 class UserActivityEventExcludedObjectTypeCondition extends AbstractMultiSelectCondition implements IObjectListCondition
 {
@@ -40,10 +41,6 @@ class UserActivityEventExcludedObjectTypeCondition extends AbstractMultiSelectCo
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserActivityEventList)) {
-            throw new InvalidObjectArgument($objectList, UserActivityEventList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add(
             'user_activity_event.objectTypeID NOT IN (?)',
             [$conditionData[$this->fieldName]]
diff --git a/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophiesCondition.class.php b/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophiesCondition.class.php
index 6372e1af248..5ff75c52f31 100644
--- a/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophiesCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophiesCondition.class.php
@@ -7,7 +7,6 @@
 use wcf\data\user\trophy\UserTrophyList;
 use wcf\system\condition\AbstractMultiSelectCondition;
 use wcf\system\condition\IObjectListCondition;
-use wcf\system\exception\InvalidObjectArgument;
 
 /**
  * Condition implementation for the excluded trophies.
@@ -16,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @implements IObjectListCondition<UserTrophyList>
  */
 class UserTrophyExcludedTrophiesCondition extends AbstractMultiSelectCondition implements IObjectListCondition
 {
@@ -39,10 +40,6 @@ class UserTrophyExcludedTrophiesCondition extends AbstractMultiSelectCondition i
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserTrophyList)) {
-            throw new InvalidObjectArgument($objectList, UserTrophyList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add('user_trophy.trophyID NOT IN (?)', [$conditionData[$this->fieldName]]);
     }
 
diff --git a/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophyCategoriesCondition.class.php b/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophyCategoriesCondition.class.php
index 34cb4bb1732..0e43b3fd33c 100644
--- a/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophyCategoriesCondition.class.php
+++ b/wcfsetup/install/files/lib/system/condition/user/trophy/UserTrophyExcludedTrophyCategoriesCondition.class.php
@@ -7,7 +7,6 @@
 use wcf\data\user\trophy\UserTrophyList;
 use wcf\system\condition\AbstractMultiSelectCondition;
 use wcf\system\condition\IObjectListCondition;
-use wcf\system\exception\InvalidObjectArgument;
 
 /**
  * Condition implementation for the excluded trophies.
@@ -16,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @implements IObjectListCondition<UserTrophyList>
  */
 class UserTrophyExcludedTrophyCategoriesCondition extends AbstractMultiSelectCondition implements IObjectListCondition
 {
@@ -39,10 +40,6 @@ class UserTrophyExcludedTrophyCategoriesCondition extends AbstractMultiSelectCon
      */
     public function addObjectListCondition(DatabaseObjectList $objectList, array $conditionData)
     {
-        if (!($objectList instanceof UserTrophyList)) {
-            throw new InvalidObjectArgument($objectList, UserTrophyList::class, 'Object list');
-        }
-
         $objectList->getConditionBuilder()->add('trophy.categoryID NOT IN (?)', [$conditionData[$this->fieldName]]);
     }
 
diff --git a/wcfsetup/install/files/lib/system/cronjob/CronjobScheduler.class.php b/wcfsetup/install/files/lib/system/cronjob/CronjobScheduler.class.php
index 8b59de90e85..cd55edbd9a8 100644
--- a/wcfsetup/install/files/lib/system/cronjob/CronjobScheduler.class.php
+++ b/wcfsetup/install/files/lib/system/cronjob/CronjobScheduler.class.php
@@ -25,9 +25,9 @@ final class CronjobScheduler extends SingletonFactory
 {
     /**
      * cached times of the next and after next cronjob execution
-     * @var int[]
+     * @var array{afterNextExec: int, nextExec: int}
      */
-    protected $cache = [];
+    private array $cache;
 
     /**
      * @inheritDoc
@@ -40,7 +40,7 @@ protected function init()
     /**
      * Executes outstanding cronjobs.
      */
-    public function executeCronjobs()
+    public function executeCronjobs(): void
     {
         // break if there are no outstanding cronjobs
         if ($this->cache['nextExec'] > TIME_NOW && $this->cache['afterNextExec'] > TIME_NOW) {
@@ -99,10 +99,8 @@ public function executeCronjobs()
 
     /**
      * Returns the next execution time.
-     *
-     * @return  int
      */
-    public function getNextExec()
+    public function getNextExec(): int
     {
         return $this->cache['nextExec'];
     }
@@ -111,7 +109,7 @@ public function getNextExec()
      * Resets any cronjobs that have previously failed to execute. Cronjobs that have failed too often will
      * be disabled automatically.
      */
-    private function resetFailedCronjobs()
+    private function resetFailedCronjobs(): void
     {
         WCF::getDB()->beginTransaction();
         /** @noinspection PhpUnusedLocalVariableInspection */
@@ -200,8 +198,10 @@ private function resetFailedCronjobs()
 
     /**
      * Loads outstanding cronjobs.
+     *
+     * @return CronjobEditor[]
      */
-    private function loadCronjobs()
+    private function loadCronjobs(): array
     {
         WCF::getDB()->beginTransaction();
         /** @noinspection PhpUnusedLocalVariableInspection */
@@ -257,7 +257,7 @@ private function loadCronjobs()
      *
      * @throws  SystemException
      */
-    private function executeCronjob(CronjobEditor $cronjobEditor, CronjobLogEditor $logEditor)
+    private function executeCronjob(CronjobEditor $cronjobEditor, CronjobLogEditor $logEditor): void
     {
         $className = $cronjobEditor->className;
         if (!\class_exists($className)) {
@@ -279,10 +279,8 @@ private function executeCronjob(CronjobEditor $cronjobEditor, CronjobLogEditor $
 
     /**
      * Logs cronjob exec success or failure.
-     *
-     * @param \Throwable $exception
      */
-    private function logResult(CronjobLogEditor $logEditor, $exception = null)
+    private function logResult(CronjobLogEditor $logEditor, ?\Throwable $exception = null): void
     {
         if ($exception !== null) {
             \wcf\functions\exception\logThrowable($exception);
@@ -309,7 +307,7 @@ private function logResult(CronjobLogEditor $logEditor, $exception = null)
     /**
      * Loads the cached data for cronjob execution.
      */
-    private function loadCache()
+    private function loadCache(): void
     {
         $this->cache = CronjobCacheBuilder::getInstance()->getData();
     }
@@ -317,7 +315,7 @@ private function loadCache()
     /**
      * Clears the cronjob data cache.
      */
-    public static function clearCache()
+    public static function clearCache(): void
     {
         CronjobCacheBuilder::getInstance()->reset();
     }
diff --git a/wcfsetup/install/files/lib/system/cronjob/ICronjob.class.php b/wcfsetup/install/files/lib/system/cronjob/ICronjob.class.php
index 32450a30f7d..92356bb0302 100644
--- a/wcfsetup/install/files/lib/system/cronjob/ICronjob.class.php
+++ b/wcfsetup/install/files/lib/system/cronjob/ICronjob.class.php
@@ -16,7 +16,7 @@ interface ICronjob
     /**
      * Executes the cronjob.
      *
-     * @param Cronjob $cronjob
+     * @return void
      */
     public function execute(Cronjob $cronjob);
 }
diff --git a/wcfsetup/install/files/lib/system/database/Database.class.php b/wcfsetup/install/files/lib/system/database/Database.class.php
index de3a0f09ff6..ff7440f5037 100644
--- a/wcfsetup/install/files/lib/system/database/Database.class.php
+++ b/wcfsetup/install/files/lib/system/database/Database.class.php
@@ -101,7 +101,7 @@ abstract class Database
 
     /**
      * default driver options passed to the PDO constructor
-     * @var array
+     * @var mixed[]
      */
     protected $defaultDriverOptions = [];
 
@@ -115,7 +115,7 @@ abstract class Database
      * @param int $port SQL database server port
      * @param bool $failsafeTest
      * @param bool $tryToCreateDatabase
-     * @param array $defaultDriverOptions
+     * @param mixed[] $defaultDriverOptions
      */
     public function __construct(
         $host,
@@ -141,6 +141,9 @@ public function __construct(
         $this->connect();
     }
 
+    /**
+     * @return void
+     */
     public function enableDebugMode()
     {
         $this->preparedStatementClassName = DebugPreparedStatement::class;
@@ -148,6 +151,8 @@ public function enableDebugMode()
 
     /**
      * Connects to database server.
+     *
+     * @return void
      */
     abstract public function connect();
 
@@ -520,6 +525,8 @@ public function getQueryCount()
 
     /**
      * Increments the query counter by one.
+     *
+     * @return void
      */
     public function incrementQueryCount()
     {
@@ -543,7 +550,7 @@ public function getEditor()
     /**
      * Returns true if this database type is supported.
      *
-     * @return  bool
+     * @return bool
      */
     public static function isSupported()
     {
@@ -552,6 +559,8 @@ public static function isSupported()
 
     /**
      * Sets default connection attributes.
+     *
+     * @return void
      */
     protected function setAttributes()
     {
diff --git a/wcfsetup/install/files/lib/system/database/Redis.class.php b/wcfsetup/install/files/lib/system/database/Redis.class.php
index 7e6a7fe7345..3d544e670bc 100644
--- a/wcfsetup/install/files/lib/system/database/Redis.class.php
+++ b/wcfsetup/install/files/lib/system/database/Redis.class.php
@@ -19,7 +19,7 @@
  * @method  mixed      hGet($key, $hashKey)
  * @method  int     hSet($key, $hashKey, $value)
  * @method  int     incr($key)
- * @method  array      info($option = null)
+ * @method  mixed[]      info($option = null)
  * @method  bool        setex($key, $ttl, $value)
  * @method  bool        setnx($key, $value)
  * @method  int     ttl($key)
@@ -93,8 +93,8 @@ public function __construct($dsn)
      * Passes all method calls down to the underlying Redis connection.
      *
      * @param string $name
-     * @param array $arguments
-     * @return  mixed
+     * @param mixed[] $arguments
+     * @return mixed
      */
     public function __call($name, array $arguments)
     {
diff --git a/wcfsetup/install/files/lib/system/database/editor/DatabaseEditor.class.php b/wcfsetup/install/files/lib/system/database/editor/DatabaseEditor.class.php
index b99ca8ec233..8a009d5136d 100644
--- a/wcfsetup/install/files/lib/system/database/editor/DatabaseEditor.class.php
+++ b/wcfsetup/install/files/lib/system/database/editor/DatabaseEditor.class.php
@@ -11,6 +11,36 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type ColumnDefinition array{
+ *  autoIncrement?: bool|0|1,
+ *  decimals?: int,
+ *  default?: string|int|float,
+ *  key?: string|false,
+ *  length?: ?int,
+ *  notNull?: bool|0|1,
+ *  type: string,
+ *  values?: string,
+ * }
+ * @phpstan-type ForeignKeyDefinition array{
+ *  action?: string,
+ *  operation?: string,
+ *  columns: string,
+ *  referencedTable: string,
+ *  referencedColumns: string,
+ *  'ON DELETE'?: string,
+ *  'ON UPDATE'?: string,
+ * }
+ * @phpstan-type IndexDefinition array{type: string, columns: string}
+ * @phpstan-type ExistingColumnDefinition array{
+ *  type: string,
+ *  length?: ?int,
+ *  notNull: bool,
+ *  key: string,
+ *  default: string|int|float|null,
+ *  autoIncrement: bool,
+ *  enumValues: string,
+ *  decimals: int,
+ * }
  */
 abstract class DatabaseEditor
 {
@@ -33,7 +63,7 @@ public function __construct(Database $dbObj)
     /**
      * Returns all existing table names.
      *
-     * @return  array       $existingTables
+     * @return string[] $existingTables
      */
     abstract public function getTableNames();
 
@@ -41,14 +71,15 @@ abstract public function getTableNames();
      * Returns the columns of a table.
      *
      * @param string $tableName
-     * @return  array       $columns
+     * @return mixed[]
      */
     abstract public function getColumns($tableName);
 
     /**
      * Returns information on the foreign keys of a table.
      *
-     * @return  array
+     * @param string $tableName
+     * @return array<string, array{columns: string[], referencedColumns: string[], referencedTable?: string, 'ON DELETE'?: string, 'ON UPDATE'?: string}>
      */
     public function getForeignKeys($tableName)
     {
@@ -67,7 +98,7 @@ abstract public function getIndices($tableName);
      * Returns information on the indices of a table.
      *
      * @param string $tableName
-     * @return  array
+     * @return array<string, array{columns: string[], type: string}>
      */
     public function getIndexInformation($tableName)
     {
@@ -78,8 +109,9 @@ public function getIndexInformation($tableName)
      * Creates a new database table.
      *
      * @param string $tableName
-     * @param array $columns
-     * @param array $indices
+     * @param array<array{name: string, data: ColumnDefinition}> $columns
+     * @param array<array{name: string, data: IndexDefinition|ForeignKeyDefinition}> $indices
+     * @return void
      */
     abstract public function createTable($tableName, $columns, $indices = []);
 
@@ -87,6 +119,7 @@ abstract public function createTable($tableName, $columns, $indices = []);
      * Drops a database table.
      *
      * @param string $tableName
+     * @return void
      */
     abstract public function dropTable($tableName);
 
@@ -95,7 +128,8 @@ abstract public function dropTable($tableName);
      *
      * @param string $tableName
      * @param string $columnName
-     * @param array $columnData
+     * @param ColumnDefinition $columnData
+     * @return void
      */
     abstract public function addColumn($tableName, $columnName, $columnData);
 
@@ -105,7 +139,8 @@ abstract public function addColumn($tableName, $columnName, $columnData);
      * @param string $tableName
      * @param string $oldColumnName
      * @param string $newColumnName
-     * @param array $newColumnData
+     * @param ColumnDefinition $newColumnData
+     * @return void
      */
     abstract public function alterColumn($tableName, $oldColumnName, $newColumnName, $newColumnData);
 
@@ -113,7 +148,8 @@ abstract public function alterColumn($tableName, $oldColumnName, $newColumnName,
      * Adds, alters and drops multiple columns at once.
      *
      * @param string $tableName
-     * @param array $alterData
+     * @param array<string|int, mixed[]> $alterData
+     * @return void
      */
     public function alterColumns($tableName, $alterData)
     {
@@ -125,6 +161,7 @@ public function alterColumns($tableName, $alterData)
      *
      * @param string $tableName
      * @param string $columnName
+     * @return void
      */
     abstract public function dropColumn($tableName, $columnName);
 
@@ -133,7 +170,8 @@ abstract public function dropColumn($tableName, $columnName);
      *
      * @param string $tableName
      * @param string $indexName
-     * @param array $indexData
+     * @param IndexDefinition $indexData
+     * @return void
      */
     abstract public function addIndex($tableName, $indexName, $indexData);
 
@@ -142,7 +180,8 @@ abstract public function addIndex($tableName, $indexName, $indexData);
      *
      * @param string $tableName
      * @param string $indexName
-     * @param array $indexData
+     * @param ForeignKeyDefinition $indexData
+     * @return void
      */
     abstract public function addForeignKey($tableName, $indexName, $indexData);
 
@@ -151,6 +190,7 @@ abstract public function addForeignKey($tableName, $indexName, $indexData);
      *
      * @param string $tableName
      * @param string $indexName
+     * @return void
      */
     abstract public function dropIndex($tableName, $indexName);
 
@@ -158,6 +198,7 @@ abstract public function dropIndex($tableName, $indexName);
      * Drops existing primary keys.
      *
      * @param string $tableName
+     * @return void
      */
     abstract public function dropPrimaryKey($tableName);
 
@@ -166,6 +207,7 @@ abstract public function dropPrimaryKey($tableName);
      *
      * @param string $tableName
      * @param string $indexName
+     * @return void
      */
     abstract public function dropForeignKey($tableName, $indexName);
 }
diff --git a/wcfsetup/install/files/lib/system/database/editor/MySQLDatabaseEditor.class.php b/wcfsetup/install/files/lib/system/database/editor/MySQLDatabaseEditor.class.php
index 827235b2934..e389f2fd48f 100644
--- a/wcfsetup/install/files/lib/system/database/editor/MySQLDatabaseEditor.class.php
+++ b/wcfsetup/install/files/lib/system/database/editor/MySQLDatabaseEditor.class.php
@@ -12,6 +12,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type ColumnDefinition from DatabaseEditor
+ * @phpstan-import-type IndexDefinition from DatabaseEditor
  */
 class MySQLDatabaseEditor extends DatabaseEditor
 {
@@ -444,8 +446,8 @@ public function dropForeignKey($tableName, $indexName)
      * Builds a column definition for execution in a create table or alter table statement.
      *
      * @param string $columnName
-     * @param array $columnData
-     * @return  string
+     * @param ColumnDefinition $columnData
+     * @return string
      */
     protected function buildColumnDefinition($columnName, $columnData)
     {
@@ -488,8 +490,8 @@ protected function buildColumnDefinition($columnName, $columnData)
      * Builds a index definition for execution in a create table or alter table statement.
      *
      * @param string $indexName
-     * @param array $indexData
-     * @return  string
+     * @param IndexDefinition $indexData
+     * @return string
      */
     protected function buildIndexDefinition($indexName, $indexData)
     {
diff --git a/wcfsetup/install/files/lib/system/database/exception/DatabaseQueryExecutionException.class.php b/wcfsetup/install/files/lib/system/database/exception/DatabaseQueryExecutionException.class.php
index 40557452c85..8fe35f1d485 100644
--- a/wcfsetup/install/files/lib/system/database/exception/DatabaseQueryExecutionException.class.php
+++ b/wcfsetup/install/files/lib/system/database/exception/DatabaseQueryExecutionException.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\database\exception;
 
+use wcf\system\database\statement\PreparedStatement;
 use wcf\system\exception\IExtraInformationException;
 use wcf\util\StringUtil;
 
@@ -13,23 +14,24 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  * @method mixed|int getCode()
+ * @phpstan-import-type ParameterValues from PreparedStatement
  */
 class DatabaseQueryExecutionException extends DatabaseQueryException implements IExtraInformationException
 {
     /**
      * Parameters that were passed to execute().
-     * @var array
+     * @var ParameterValues
      */
     protected $parameters = [];
 
     /**
-     * @var string|null
+     * @var ?string
      * @since 5.3
      */
     protected $sqlState;
 
     /**
-     * @var string|null
+     * @var ?string
      * @since 5.3
      */
     protected $driverCode;
@@ -37,7 +39,8 @@ class DatabaseQueryExecutionException extends DatabaseQueryException implements
     /** @noinspection PhpMissingParentConstructorInspection */
 
     /**
-     * @inheritDoc
+     * @param string $message
+     * @param ParameterValues $parameters
      */
     public function __construct($message, $parameters, ?\PDOException $previous = null)
     {
@@ -54,7 +57,7 @@ public function __construct($message, $parameters, ?\PDOException $previous = nu
     /**
      * Returns the ANSI SQLSTATE or null.
      *
-     * @return string|null
+     * @return ?string
      * @since 5.3
      */
     public function getSqlState()
@@ -65,7 +68,7 @@ public function getSqlState()
     /**
      * Returns the driver specific error code or null.
      *
-     * @return string|null
+     * @return ?string
      * @since 5.3
      */
     public function getDriverCode()
@@ -76,7 +79,7 @@ public function getDriverCode()
     /**
      * Returns the parameters that were passed to execute().
      *
-     * @return  array
+     * @return ParameterValues
      */
     public function getParameters()
     {
diff --git a/wcfsetup/install/files/lib/system/database/statement/DebugPreparedStatement.class.php b/wcfsetup/install/files/lib/system/database/statement/DebugPreparedStatement.class.php
index fa3d5628c10..c038d71dc42 100644
--- a/wcfsetup/install/files/lib/system/database/statement/DebugPreparedStatement.class.php
+++ b/wcfsetup/install/files/lib/system/database/statement/DebugPreparedStatement.class.php
@@ -12,6 +12,9 @@
  */
 class DebugPreparedStatement extends PreparedStatement
 {
+    /**
+     * @var bool
+     */
     protected $debugDidExecuteOnce = false;
 
     /**
@@ -109,7 +112,7 @@ public function fetchMap($keyColumn, $valueColumn, $uniqueKey = true)
     /**
      * @inheritDoc
      */
-    protected function debugThrowIfNotExecutedBefore()
+    protected function debugThrowIfNotExecutedBefore(): void
     {
         if (!$this->debugDidExecuteOnce) {
             throw new \RuntimeException('Attempted to fetch data from a statement without executing it at least once.');
diff --git a/wcfsetup/install/files/lib/system/database/statement/PreparedStatement.class.php b/wcfsetup/install/files/lib/system/database/statement/PreparedStatement.class.php
index 27cd8995f2b..abb2bc8a74d 100644
--- a/wcfsetup/install/files/lib/system/database/statement/PreparedStatement.class.php
+++ b/wcfsetup/install/files/lib/system/database/statement/PreparedStatement.class.php
@@ -18,6 +18,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
  * @mixin   \PDOStatement
+ * @phpstan-type ParameterValues list<string|int|float|null|(string|int|float|null)[]>
  */
 class PreparedStatement
 {
@@ -29,7 +30,7 @@ class PreparedStatement
 
     /**
      * SQL query parameters
-     * @var array
+     * @var ParameterValues
      */
     protected $parameters = [];
 
@@ -46,10 +47,6 @@ class PreparedStatement
     protected $query = '';
 
     /**
-     * Creates a new PreparedStatement object.
-     *
-     * @param Database $database
-     * @param \PDOStatement $pdoStatement
      * @param string $query SQL query
      */
     public function __construct(Database $database, \PDOStatement $pdoStatement, $query = '')
@@ -63,9 +60,9 @@ public function __construct(Database $database, \PDOStatement $pdoStatement, $qu
      * Delegates inaccessible methods calls to the decorated object.
      *
      * @param string $name
-     * @param array $arguments
-     * @return  mixed
-     * @throws  SystemException
+     * @param mixed[] $arguments
+     * @return mixed
+     * @throws SystemException
      */
     public function __call($name, $arguments)
     {
@@ -83,8 +80,9 @@ public function __call($name, $arguments)
     /**
      * Executes a prepared statement.
      *
-     * @param array $parameters
-     * @throws  DatabaseQueryExecutionException
+     * @param ParameterValues $parameters
+     * @return void
+     * @throws DatabaseQueryExecutionException
      */
     public function execute(array $parameters = [])
     {
@@ -152,7 +150,7 @@ static function ($matches) use (&$benchmarkParameters) {
      * Fetches the next row from a result set in an array.
      *
      * @param int $type fetch type
-     * @return  mixed
+     * @return mixed
      */
     public function fetchArray($type = null)
     {
@@ -172,8 +170,8 @@ public function fetchArray($type = null)
      * this method!
      *
      * @param int $type fetch type
-     * @return  mixed
-     * @see     \wcf\system\database\statement\PreparedStatement::fetchArray()
+     * @return mixed
+     * @see \wcf\system\database\statement\PreparedStatement::fetchArray()
      */
     public function fetchSingleRow($type = null)
     {
@@ -191,8 +189,8 @@ public function fetchSingleRow($type = null)
      * this method!
      *
      * @param int $columnNumber
-     * @return  mixed
-     * @see     \PDOStatement::fetchColumn()
+     * @return mixed
+     * @see \PDOStatement::fetchColumn()
      */
     public function fetchSingleColumn($columnNumber = 0)
     {
@@ -207,7 +205,7 @@ public function fetchSingleColumn($columnNumber = 0)
      *
      * @template T of DatabaseObject
      * @param class-string<T> $className
-     * @return T|null
+     * @return ?T
      */
     public function fetchObject($className)
     {
@@ -228,8 +226,8 @@ public function fetchObject($className)
      *
      * @template T of DatabaseObject
      * @param class-string<T> $className
-     * @return  T|null
-     * @since       5.3
+     * @return ?T
+     * @since 5.3
      */
     public function fetchSingleObject($className)
     {
@@ -246,8 +244,8 @@ public function fetchSingleObject($className)
      *
      * @template T of DatabaseObject
      * @param class-string<T> $className
-     * @param string|null $keyProperty
-     * @return  T[]
+     * @param ?string $keyProperty
+     * @return T[]
      */
     public function fetchObjects($className, $keyProperty = null)
     {
@@ -269,7 +267,7 @@ public function fetchObjects($className, $keyProperty = null)
      * @param string $keyColumn name of the key column
      * @param string $valueColumn name of the value column
      * @param bool $uniqueKey if `true`, a one-dimensional array is returned, otherwise, for each key an array of fetched values is returned
-     * @return  array<string|int, (string|int)|(string|int)[]>
+     * @return array<string|int, string|int|float|(string|int|float)[]>
      */
     public function fetchMap($keyColumn, $valueColumn, $uniqueKey = true)
     {
@@ -294,6 +292,8 @@ public function fetchMap($keyColumn, $valueColumn, $uniqueKey = true)
     }
 
     /**
+     * @param string $column
+     * @return list<string|int|float>
      * @deprecated 5.4 - Use ->fetchAll(\PDO::FETCH_COLUMN)
      */
     public function fetchList($column)
@@ -314,8 +314,8 @@ public function fetchList($column)
     /**
      * Counts number of affected rows by the last sql statement (INSERT, UPDATE or DELETE).
      *
-     * @return  int     number of affected rows
-     * @throws  DatabaseQueryException
+     * @return int number of affected rows
+     * @throws DatabaseQueryException
      */
     public function getAffectedRows()
     {
@@ -344,7 +344,7 @@ public function getErrorNumber()
     /**
      * Returns the description of the last error.
      *
-     * @return  string
+     * @return string
      */
     public function getErrorDesc()
     {
@@ -355,7 +355,7 @@ public function getErrorDesc()
     /**
      * Returns the SQL query of this statement.
      *
-     * @return  string
+     * @return string
      */
     public function getSQLQuery()
     {
@@ -365,7 +365,7 @@ public function getSQLQuery()
     /**
      * Returns the SQL query parameters of this statement.
      *
-     * @return  array
+     * @return ParameterValues
      */
     public function getSQLParameters()
     {
diff --git a/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php b/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
index 265beb3b92b..388f63941ef 100644
--- a/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/DatabaseTableChangeProcessor.class.php
@@ -930,7 +930,14 @@ private function finalizeTableLog(DatabaseTable $table): void
      * Returns the log entry for the given column or `null` if there is no explicit entry for
      * this column.
      *
-     * @since       5.4
+     * @return ?array{
+     *  packageID: int,
+     *  sqlTable: string,
+     *  sqlColumn: string,
+     *  sqlIndex: string,
+     *  isDone: 0|1
+     * }
+     * @since 5.4
      */
     private function getColumnLog(string $tableName, IDatabaseTableColumn $column): ?array
     {
@@ -1029,7 +1036,7 @@ private function prepareColumnLog(string $tableName, IDatabaseTableColumn $colum
     /**
      * Prepares the log entry for adding the given foreign key.
      */
-    private function prepareForeignKeyLog(string $tableName, DatabaseTableForeignKey $foreignKey)
+    private function prepareForeignKeyLog(string $tableName, DatabaseTableForeignKey $foreignKey): void
     {
         $this->prepareLog(['sqlTable' => $tableName, 'sqlIndex' => $foreignKey->getName()]);
     }
@@ -1098,6 +1105,14 @@ public function process(): void
     /**
      * Checks if the relevant table layout changes can be executed and returns an array with information
      * on all validation errors.
+     *
+     * @return list<array{
+     *  tableName: string,
+     *  type: string,
+     *  columnName?: string,
+     *  columnNames?: string,
+     *  referencedTableName?: string,
+     * }>
      */
     public function validate(): array
     {
diff --git a/wcfsetup/install/files/lib/system/database/table/column/IDatabaseTableColumn.class.php b/wcfsetup/install/files/lib/system/database/table/column/IDatabaseTableColumn.class.php
index 4b6a40fff22..dbbfb3f7cc2 100644
--- a/wcfsetup/install/files/lib/system/database/table/column/IDatabaseTableColumn.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/column/IDatabaseTableColumn.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\database\table\column;
 
+use wcf\system\database\editor\DatabaseEditor;
+
 /**
  * Represents a column of a database table.
  *
@@ -9,18 +11,28 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ * @phpstan-import-type ExistingColumnDefinition from DatabaseEditor
  */
 interface IDatabaseTableColumn
 {
     /**
      * Marks the column to be dropped and returns the column.
-     *
-     * @return  $this
      */
     public function drop(): static;
 
     /**
      * Returns the data used by `DatabaseEditor` to add the column to a table.
+     *
+     * @return array{
+     *  notNull: 0|1,
+     *  type: string,
+     *  default?: ?mixed,
+     *  autoIncrement?: 0|1,
+     *  key?: string,
+     *  decimals?: int,
+     *  values?: string,
+     *  length?: ?int,
+     * }
      */
     public function getData(): array;
 
@@ -32,7 +44,7 @@ public function getName(): string;
     /**
      * Returns the new name of the column or `null` if the column's name is unchanged.
      *
-     * @since       5.4
+     * @since 5.4
      */
     public function getNewName(): ?string;
 
@@ -48,23 +60,18 @@ public function isNotNull(): bool;
 
     /**
      * Sets the name of the column and returns the column.
-     *
-     * @return  $this
      */
     public function name(string $name): static;
 
     /**
      * Sets if the values of the column cannot be `null`.
-     *
-     * @return  $this
      */
     public function notNull(bool $notNull = true): static;
 
     /**
      * Sets the new name of the column and returns the column.
      *
-     * @since       5.4
-     * @return $this
+     * @since 5.4
      */
     public function renameTo(string $newName): static;
 
@@ -75,16 +82,13 @@ public function willBeDropped(): bool;
 
     /**
      * Returns a `DatabaseTableColumn` object with the given name.
-     *
-     * @return  $this
      */
     public static function create(string $name): static;
 
     /**
      * Returns a `DatabaseTableColumn` object with the given name and data.
      *
-     * @param array $data data returned by `DatabaseEditor::getColumns()`
-     * @return  $this
+     * @param ExistingColumnDefinition $data data returned by `DatabaseEditor::getColumns()`
      */
     public static function createFromData(string $name, array $data): static;
 }
diff --git a/wcfsetup/install/files/lib/system/database/table/column/NotNullVarchar255DatabaseTableColumn.class.php b/wcfsetup/install/files/lib/system/database/table/column/NotNullVarchar255DatabaseTableColumn.class.php
index fbbf73c982e..ca4de03d13a 100644
--- a/wcfsetup/install/files/lib/system/database/table/column/NotNullVarchar255DatabaseTableColumn.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/column/NotNullVarchar255DatabaseTableColumn.class.php
@@ -12,14 +12,12 @@
  */
 final class NotNullVarchar255DatabaseTableColumn
 {
-    public static function create($name): VarcharDatabaseTableColumn
+    public static function create(string $name): VarcharDatabaseTableColumn
     {
         return VarcharDatabaseTableColumn::create($name)
             ->notNull()
             ->length(255);
     }
 
-    private function __construct()
-    {
-    }
+    private function __construct() {}
 }
diff --git a/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableForeignKey.class.php b/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableForeignKey.class.php
index efc8c1dd0d3..9429283ef9c 100644
--- a/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableForeignKey.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableForeignKey.class.php
@@ -27,48 +27,43 @@ final class DatabaseTableForeignKey
      * name of the foreign key
      * @var string
      */
-    protected $name;
+    protected string $name;
 
     /**
      * action executed in referenced table if row is deleted
-     * @var null|string
      */
-    protected $onDelete;
+    protected ?string $onDelete = null;
 
     /**
      * action executed in referenced table if row is updated
-     * @var null|string
      */
-    protected $onUpdate;
+    protected ?string $onUpdate = null;
 
     /**
      * relevant columns in referenced table
      * @var string[]
      */
-    protected $referencedColumns;
+    protected array $referencedColumns;
 
     /**
      * name of referenced table
-     * @var string
      */
-    protected $referencedTable;
+    protected string $referencedTable;
 
     /**
      * valid on delete/update actions
      * @var string[]
      */
-    const VALID_ACTIONS = [
+    public const VALID_ACTIONS = [
         'CASCADE',
         'NO ACTION',
         'SET NULL',
     ];
 
     /**
-     * Creates a new `DatabaseTableForeignKey` object.
-     *
      * @param string $name column name
      */
-    protected function __construct($name)
+    protected function __construct(string $name)
     {
         $this->name = $name;
     }
@@ -77,9 +72,9 @@ protected function __construct($name)
      * Sets the columns affected by the foreign key and returns the foreign key.
      *
      * @param string[] $columns columns affected by foreign key
-     * @return  $this               this foreign key
+     * @return $this this foreign key
      */
-    public function columns(array $columns)
+    public function columns(array $columns): self
     {
         $this->columns = \array_values($columns);
 
@@ -91,10 +86,8 @@ public function columns(array $columns)
      *
      * If the key belongs to a database table layout not created from an existing database table,
      * the name might be empty.
-     *
-     * @return  string
      */
-    public function getName()
+    public function getName(): string
     {
         return $this->name;
     }
@@ -102,10 +95,10 @@ public function getName()
     /**
      * Returns the columns affected by the foreign key
      *
-     * @return  string[]            columns affected by foreign key
-     * @throws  \BadMethodCallException     if not columns have been set
+     * @return string[] columns affected by foreign key
+     * @throws \BadMethodCallException if not columns have been set
      */
-    public function getColumns()
+    public function getColumns(): array
     {
         if (!isset($this->columns)) {
             throw new \BadMethodCallException(
@@ -119,9 +112,15 @@ public function getColumns()
     /**
      * Returns the data used by `DatabaseEditor` to add the foreign key to a table.
      *
-     * @return  array
+     * @return array{
+     *  columns: string,
+     *  referencedColumns: string,
+     *  referencedTable: string,
+     *  'ON DELETE': ?string,
+     *  'ON UPDATE': ?string,
+     * }
      */
-    public function getData()
+    public function getData(): array
     {
         return [
             'columns' => \implode(',', $this->getColumns()),
@@ -135,9 +134,9 @@ public function getData()
     /**
      * Returns the data used to compare foreign keys.
      *
-     * @return      array
+     * @return array{columns: string, referencedColumns: string, referencedTable: string}
      */
-    public function getDiffData()
+    public function getDiffData(): array
     {
         return [
             'columns' => \implode(',', $this->getColumns()),
@@ -149,10 +148,8 @@ public function getDiffData()
     /**
      * Returns the action executed in referenced table if row is deleted or `null` if no such
      * action has been set.
-     *
-     * @return  null|string
      */
-    public function getOnDelete()
+    public function getOnDelete(): ?string
     {
         return $this->onDelete;
     }
@@ -160,10 +157,8 @@ public function getOnDelete()
     /**
      * Returns the action executed in referenced table if row is updated or `null` if no such
      * action has been set.
-     *
-     * @return  null|string
      */
-    public function getOnUpdate()
+    public function getOnUpdate(): ?string
     {
         return $this->onUpdate;
     }
@@ -171,12 +166,12 @@ public function getOnUpdate()
     /**
      * Returns the relevant columns in referenced table.
      *
-     * @return  string[]
-     * @throws  \BadMethodCallException     if referenced columns have not been set
+     * @return string[]
+     * @throws \BadMethodCallException if referenced columns have not been set
      */
-    public function getReferencedColumns()
+    public function getReferencedColumns(): array
     {
-        if ($this->referencedColumns === null) {
+        if (!isset($this->referencedColumns)) {
             throw new \BadMethodCallException(
                 "Before getting the referenced columns, they must be set for foreign key '{$this->getName()}'."
             );
@@ -188,12 +183,11 @@ public function getReferencedColumns()
     /**
      * Returns the name of the referenced table.
      *
-     * @return  string
-     * @throws  \BadMethodCallException     if referenced table has not been set
+     * @throws \BadMethodCallException if referenced table has not been set
      */
-    public function getReferencedTable()
+    public function getReferencedTable(): string
     {
-        if ($this->referencedTable === null) {
+        if (!isset($this->referencedTable)) {
             throw new \BadMethodCallException(
                 "Before getting the referenced table, it must be set for foreign key '{$this->getName()}'."
             );
@@ -204,11 +198,8 @@ public function getReferencedTable()
 
     /**
      * Sets the name of the foreign key.
-     *
-     * @param string $name index name
-     * @return  $this               this index
      */
-    public function name($name)
+    public function name(string $name): self
     {
         $this->name = $name;
 
@@ -220,10 +211,10 @@ public function name($name)
      * key.
      *
      * @param ?string $onDelete action executed in referenced table if row is deleted
-     * @return  $this               this foreign key
-     * @throws  \InvalidArgumentException   if given action is invalid
+     * @return $this this foreign key
+     * @throws \InvalidArgumentException if given action is invalid
      */
-    public function onDelete($onDelete)
+    public function onDelete(?string $onDelete): self
     {
         if ($onDelete !== null && !\in_array($onDelete, static::VALID_ACTIONS)) {
             throw new \InvalidArgumentException("Unknown on delete action '{$onDelete}'.");
@@ -239,8 +230,8 @@ public function onDelete($onDelete)
      * key.
      *
      * @param ?string $onUpdate action executed in referenced table if row is updated
-     * @return  $this               this foreign key
-     * @throws  \InvalidArgumentException   if given action is invalid
+     * @return $this this foreign key
+     * @throws \InvalidArgumentException if given action is invalid
      */
     public function onUpdate($onUpdate)
     {
@@ -257,7 +248,7 @@ public function onUpdate($onUpdate)
      * Sets the relevant columns of the referenced table and returns the foreign key.
      *
      * @param string[] $referencedColumns columns of referenced table
-     * @return  $this                   this foreign key
+     * @return $this this foreign key
      */
     public function referencedColumns(array $referencedColumns)
     {
@@ -270,7 +261,7 @@ public function referencedColumns(array $referencedColumns)
      * Sets the name of the referenced table and returns the foreign key.
      *
      * @param string $referencedTable name of referenced table
-     * @return  $this                   this foreign key
+     * @return $this this foreign key
      */
     public function referencedTable($referencedTable)
     {
@@ -285,7 +276,7 @@ public function referencedTable($referencedTable)
      * the action, by always setting it to null if the value is `RESTRICT` or `NO ACTION`.
      *
      * @param string $action
-     * @return string|null
+     * @return ?string
      */
     protected function normalizeAction($action)
     {
@@ -300,7 +291,7 @@ protected function normalizeAction($action)
      * Returns a `DatabaseTableForeignKey` object with the given name.
      *
      * @param string $name
-     * @return  static
+     * @return static
      */
     public static function create($name = '')
     {
@@ -311,8 +302,14 @@ public static function create($name = '')
      * Returns a `DatabaseTableForeignKey` object with the given name and data.
      *
      * @param string $name
-     * @param array $data data returned by `DatabaseEditor::getForeignKeys()`
-     * @return  static
+     * @param array{
+     *  columns: string[],
+     *  referencedTable: string,
+     *  referencedColumns: string[],
+     *  'ON DELETE'?: string,
+     *  'ON UPDATE': string,
+     * } $data data returned by `DatabaseEditor::getForeignKeys()`
+     * @return static
      */
     public static function createFromData($name, $data)
     {
diff --git a/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableIndex.class.php b/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableIndex.class.php
index b864d56b818..1fe1f93d545 100644
--- a/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableIndex.class.php
+++ b/wcfsetup/install/files/lib/system/database/table/index/DatabaseTableIndex.class.php
@@ -176,7 +176,7 @@ public static function create(string $name): static
     /**
      * Returns a `DatabaseTableIndex` object with the given name and data.
      *
-     * @param array $data data returned by `DatabaseEditor::getIndexInformation()`
+     * @param array{type: string, columns: string[]} $data data returned by `DatabaseEditor::getIndexInformation()`
      */
     public static function createFromData(string $name, array $data): static
     {
diff --git a/wcfsetup/install/files/lib/system/database/util/ConditionBuilder.class.php b/wcfsetup/install/files/lib/system/database/util/ConditionBuilder.class.php
index 1c05aa75f1c..f76b8c80007 100644
--- a/wcfsetup/install/files/lib/system/database/util/ConditionBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/database/util/ConditionBuilder.class.php
@@ -45,6 +45,7 @@ public function __construct($addWhereKeyword = true, $concat = 'AND')
      * Adds a new condition.
      *
      * @param mixed $condition
+     * @return void
      */
     public function add($condition)
     {
@@ -73,6 +74,7 @@ public function __toString(): string
      * Enables / disables the where keyword.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableWhereKeyword($enable = true)
     {
diff --git a/wcfsetup/install/files/lib/system/database/util/PreparedStatementConditionBuilder.class.php b/wcfsetup/install/files/lib/system/database/util/PreparedStatementConditionBuilder.class.php
index 0955749e82c..b722b4e716e 100644
--- a/wcfsetup/install/files/lib/system/database/util/PreparedStatementConditionBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/database/util/PreparedStatementConditionBuilder.class.php
@@ -15,7 +15,7 @@ class PreparedStatementConditionBuilder extends ConditionBuilder
 {
     /**
      * input parameters
-     * @var array
+     * @var array<int, mixed>
      */
     protected $parameters = [];
 
@@ -23,7 +23,8 @@ class PreparedStatementConditionBuilder extends ConditionBuilder
      * Adds a new condition. The parameters array has to be a numbered array.
      *
      * @param string $condition
-     * @param array $parameters
+     * @param array<int, mixed> $parameters
+     * @return void
      */
     public function add($condition, array $parameters = [])
     {
@@ -81,7 +82,7 @@ public function add($condition, array $parameters = [])
     /**
      * Returns the input parameters.
      *
-     * @return  array
+     * @return array<int, mixed>
      */
     public function getParameters()
     {
diff --git a/wcfsetup/install/files/lib/system/database/util/SQLParser.class.php b/wcfsetup/install/files/lib/system/database/util/SQLParser.class.php
index fc96dfbedf8..20f2d05aee0 100644
--- a/wcfsetup/install/files/lib/system/database/util/SQLParser.class.php
+++ b/wcfsetup/install/files/lib/system/database/util/SQLParser.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\database\util;
 
+use wcf\system\database\editor\DatabaseEditor;
 use wcf\system\exception\SystemException;
 use wcf\system\WCF;
 use wcf\util\ArrayUtil;
@@ -14,6 +15,9 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type ColumnDefinition from DatabaseEditor
+ * @phpstan-import-type ForeignKeyDefinition from DatabaseEditor
+ * @phpstan-import-type IndexDefinition from DatabaseEditor
  */
 class SQLParser
 {
@@ -41,6 +45,8 @@ public function __construct($queries)
 
     /**
      * Executes the sql queries.
+     *
+     * @return void
      */
     public function execute()
     {
@@ -64,7 +70,8 @@ public function execute()
      *
      * @param string $statement
      * @param string $query
-     * @throws  SystemException
+     * @return void
+     * @throws SystemException
      */
     protected function executeStatement($statement, $query)
     {
@@ -285,8 +292,9 @@ protected function executeStatement($statement, $query)
      * Executes a 'CREATE TABLE' statement.
      *
      * @param string $tableName
-     * @param array $columns
-     * @param array $indices
+     * @param list<array{name: string, data: ColumnDefinition}> $columns
+     * @param list<array{name: string, data: IndexDefinition}> $indices
+     * @return void
      */
     protected function executeCreateTableStatement($tableName, $columns, $indices = [])
     {
@@ -298,7 +306,8 @@ protected function executeCreateTableStatement($tableName, $columns, $indices =
      *
      * @param string $tableName
      * @param string $columnName
-     * @param array $columnData
+     * @param ColumnDefinition $columnData
+     * @return void
      */
     protected function executeAddColumnStatement($tableName, $columnName, $columnData)
     {
@@ -311,7 +320,8 @@ protected function executeAddColumnStatement($tableName, $columnName, $columnDat
      * @param string $tableName
      * @param string $oldColumnName
      * @param string $newColumnName
-     * @param array $newColumnData
+     * @param ColumnDefinition $newColumnData
+     * @return void
      */
     protected function executeAlterColumnStatement($tableName, $oldColumnName, $newColumnName, $newColumnData)
     {
@@ -323,7 +333,8 @@ protected function executeAlterColumnStatement($tableName, $oldColumnName, $newC
      *
      * @param string $tableName
      * @param string $indexName
-     * @param array $indexData
+     * @param IndexDefinition $indexData
+     * @return void
      */
     protected function executeAddIndexStatement($tableName, $indexName, $indexData)
     {
@@ -335,7 +346,8 @@ protected function executeAddIndexStatement($tableName, $indexName, $indexData)
      *
      * @param string $tableName
      * @param string $indexName
-     * @param array $indexData
+     * @param ForeignKeyDefinition $indexData
+     * @return void
      */
     protected function executeAddForeignKeyStatement($tableName, $indexName, $indexData)
     {
@@ -347,6 +359,7 @@ protected function executeAddForeignKeyStatement($tableName, $indexName, $indexD
      *
      * @param string $tableName
      * @param string $columnName
+     * @return void
      */
     protected function executeDropColumnStatement($tableName, $columnName)
     {
@@ -358,6 +371,7 @@ protected function executeDropColumnStatement($tableName, $columnName)
      *
      * @param string $tableName
      * @param string $indexName
+     * @return void
      */
     protected function executeDropIndexStatement($tableName, $indexName)
     {
@@ -368,6 +382,7 @@ protected function executeDropIndexStatement($tableName, $indexName)
      * Executes a 'DROP PRIMARY KEY' statement.
      *
      * @param string $tableName
+     * @return void
      */
     protected function executeDropPrimaryKeyStatement($tableName)
     {
@@ -379,6 +394,7 @@ protected function executeDropPrimaryKeyStatement($tableName)
      *
      * @param string $tableName
      * @param string $indexName
+     * @return void
      */
     protected function executeDropForeignKeyStatement($tableName, $indexName)
     {
@@ -389,6 +405,7 @@ protected function executeDropForeignKeyStatement($tableName, $indexName)
      * Executes a 'DROP TABLE' statement.
      *
      * @param string $tableName
+     * @return void
      */
     protected function executeDropTableStatement($tableName)
     {
@@ -399,6 +416,7 @@ protected function executeDropTableStatement($tableName)
      * Executes a standard ansi sql statement.
      *
      * @param string $query
+     * @return void
      */
     protected function executeStandardStatement($query)
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php b/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
index 34805c7a79e..1b856186a30 100644
--- a/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
@@ -14,6 +14,31 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       3.1
+ * @phpstan-type Configuration array{
+ *  setup?: array{
+ *      database?: array{
+ *          auto: bool,
+ *          host: string,
+ *          password: string,
+ *          username: string,
+ *      },
+ *      useDefaultInstallPath?: bool,
+ *      forceStaticCookiePrefix?: bool,
+ *  },
+ *  configuration?: array{
+ *      option?: array<string, string>,
+ *      devtools?: array<string, string>,
+ *  },
+ *  packageServerLogin?: array{
+ *      username: string,
+ *      password: string,
+ *  },
+ *  user?: list<array{
+ *      username: string,
+ *      password: string,
+ *      email: string,
+ *  }>,
+ * }
  */
 class DevtoolsSetup extends SingletonFactory
 {
@@ -25,7 +50,7 @@ class DevtoolsSetup extends SingletonFactory
 
     /**
      * configuration data
-     * @var array
+     * @var Configuration|array{}
      */
     protected $configuration = [];
 
@@ -52,7 +77,7 @@ protected function init()
     /**
      * Returns the database configuration.
      *
-     * @return array|null
+     * @return ?array{auto: bool, host: string, password: string, username: string, dbName: string}
      */
     public function getDatabaseConfig()
     {
@@ -85,7 +110,7 @@ public function getDatabaseConfig()
      * Returns true if the suggested default paths for the Core and, if exists,
      * the bundled app should be used.
      *
-     * @return      bool
+     * @return bool
      */
     public function useDefaultInstallPath()
     {
@@ -96,7 +121,7 @@ public function useDefaultInstallPath()
      * Returns true if a static cookie prefix should be used, instead of the randomized
      * value used for non-dev-mode installations.
      *
-     * @return      bool
+     * @return bool
      */
     public function forceStaticCookiePrefix()
     {
@@ -106,7 +131,7 @@ public function forceStaticCookiePrefix()
     /**
      * List of option values that will be set after the setup has completed.
      *
-     * @return      string[]
+     * @return string[]
      */
     public function getOptionOverrides()
     {
@@ -124,7 +149,7 @@ public function getOptionOverrides()
     /**
      * Returns a list of users that should be automatically created during setup.
      *
-     * @return      array|\Generator
+     * @return \Generator<array{username: string, password: string, email: string}>
      */
     public function getUsers()
     {
@@ -148,7 +173,7 @@ public function getUsers()
     /**
      * Returns the base path for projects that should be automatically imported.
      *
-     * @return      string
+     * @return string
      */
     public function getDevtoolsImportPath()
     {
@@ -157,6 +182,8 @@ public function getDevtoolsImportPath()
 
     /**
      * Returns the login data for the WoltLab package servers.
+     *
+     * @return array{username: string, password: string}|array{}
      */
     public function getPackageServerLogin(): array
     {
@@ -170,7 +197,7 @@ public function getPackageServerLogin(): array
     /**
      * Returns the raw configuration data.
      *
-     * @return array
+     * @return Configuration
      */
     public function getRawConfiguration()
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsInstaller.class.php b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsInstaller.class.php
index 1bfada23b6b..576bd240e02 100644
--- a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsInstaller.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsInstaller.class.php
@@ -75,6 +75,7 @@ public function getTar($source)
             }
 
             if ($archive !== null) {
+                // @phpstan-ignore if.alwaysTrue
                 if ($this->project->isCore()) {
                     switch ($instruction['pip']) {
                         case 'acpTemplate':
diff --git a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageArchive.class.php b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageArchive.class.php
index d94ca81447b..8ca110d9ada 100644
--- a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageArchive.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageArchive.class.php
@@ -17,13 +17,16 @@
  * @since       3.1
  *
  * @method  DevtoolsTar getTar()
+ * @property ?DevtoolsTar $tar
  */
 class DevtoolsPackageArchive extends PackageArchive
 {
+    /**
+     * @var string
+     */
     protected $packageXmlPath = '';
 
-    /** @noinspection PhpMissingParentConstructorInspection @inheritDoc */
-    public function __construct($packageXmlPath)
+    public function __construct(string $packageXmlPath)
     {
         $this->packageXmlPath = $packageXmlPath;
     }
diff --git a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageXmlWriter.class.php b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageXmlWriter.class.php
index c3d6922d586..d7e11bee40f 100644
--- a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageXmlWriter.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsPackageXmlWriter.class.php
@@ -18,7 +18,7 @@ class DevtoolsPackageXmlWriter
 {
     /**
      * data used to write the `package.xml` file
-     * @var array
+     * @var mixed[]
      */
     protected $packageXmlData;
 
@@ -38,7 +38,7 @@ class DevtoolsPackageXmlWriter
      * Creates a new `DevtoolsPackageXmlWriter` object.
      *
      * @param DevtoolsProject $project
-     * @param array $packageXmlData
+     * @param mixed[][] $packageXmlData
      */
     public function __construct(DevtoolsProject $project, array $packageXmlData)
     {
@@ -51,7 +51,7 @@ public function __construct(DevtoolsProject $project, array $packageXmlData)
      * section or `false`, otherwise.
      *
      * @param string $string
-     * @return  bool
+     * @return bool
      */
     protected function requiresCdata($string)
     {
@@ -62,6 +62,8 @@ protected function requiresCdata($string)
 
     /**
      * Writes the `package.xml` file.
+     *
+     * @return void
      */
     public function write()
     {
@@ -85,6 +87,8 @@ public function write()
 
     /**
      * Writes the `authorinformation` element.
+     *
+     * @return void
      */
     protected function writeAuthorInformation()
     {
@@ -110,6 +114,8 @@ protected function writeAuthorInformation()
 
     /**
      * Writes the `optionalpackages` element.
+     *
+     * @return void
      */
     protected function writeExcludedPackages()
     {
@@ -136,6 +142,8 @@ protected function writeExcludedPackages()
 
     /**
      * Writes the `instructions` elements.
+     *
+     * @return void
      */
     protected function writeInstructions()
     {
@@ -169,6 +177,8 @@ protected function writeInstructions()
 
     /**
      * Writes the `optionalpackages` element.
+     *
+     * @return void
      */
     protected function writeOptionalPackages()
     {
@@ -193,6 +203,7 @@ protected function writeOptionalPackages()
      *
      * @param string $information
      * @param null|string $elementName is set to lowercase version of `$information` if missing
+     * @return void
      */
     protected function writeI18nPackageInformation($information, $elementName = null)
     {
@@ -243,6 +254,8 @@ protected function writeI18nPackageInformation($information, $elementName = null
 
     /**
      * Writes the `packageinformation` element.
+     *
+     * @return void
      */
     protected function writePackageInformation()
     {
@@ -296,6 +309,8 @@ protected function writePackageInformation()
 
     /**
      * Writes the `optionalpackages` element.
+     *
+     * @return void
      */
     protected function writeRequiredPackages()
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsTar.class.php b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsTar.class.php
index 571f5e1f58a..325b7b8630a 100644
--- a/wcfsetup/install/files/lib/system/devtools/package/DevtoolsTar.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/package/DevtoolsTar.class.php
@@ -16,11 +16,13 @@ class DevtoolsTar extends Tar
 {
     /**
      * list of virtual files
-     * @var string[]
+     * @var array<string, string>
      */
     protected $files = [];
 
-    /** @noinspection PhpMissingParentConstructorInspection @inheritDoc */
+    /**
+     * @param array<string, string> $files
+     */
     public function __construct(array $files)
     {
         $this->files = $files;
@@ -30,6 +32,8 @@ public function __construct(array $files)
      * Resets the internal file list for re-use, because the devtools use
      * the same instance over and over to avoid some otherwise awkward
      * changes to the code.
+     *
+     * @return void
      */
     public function reset()
     {
@@ -42,6 +46,7 @@ public function reset()
      *
      * @param string $filename
      * @param string $fullPath
+     * @return void
      */
     public function registerFile($filename, $fullPath)
     {
@@ -117,7 +122,7 @@ public function getContentList()
     /**
      * Returns all files in the virtual file list.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getFiles()
     {
@@ -128,6 +133,7 @@ public function getFiles()
      * Sets all files in the virtual file list.
      *
      * @param string[] $files
+     * @return void
      */
     public function setFiles(array $files)
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
index d0fef7b7afd..46dac0918de 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
@@ -20,22 +20,22 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       3.1
  *
- * @method  PackageInstallationPlugin   getDecoratedObject()
  * @mixin   PackageInstallationPlugin
+ * @extends DatabaseObjectDecorator<PackageInstallationPlugin>
  */
 class DevtoolsPip extends DatabaseObjectDecorator
 {
     /**
      * project the pip object belongs to
      * @var DevtoolsProject
-     * @since   5.2
+     * @since 5.2
      */
     protected $project;
 
     /**
      * package installation plugin object
      * @var IPackageInstallationPlugin
-     * @since   5.2
+     * @since 5.2
      */
     protected $pip;
 
@@ -47,7 +47,7 @@ class DevtoolsPip extends DatabaseObjectDecorator
     /**
      * Returns true if the PIP class can be found.
      *
-     * @return      bool
+     * @return bool
      */
     public function classExists()
     {
@@ -57,7 +57,7 @@ public function classExists()
     /**
      * Returns true if the PIP is expected to be idempotent.
      *
-     * @return      bool
+     * @return bool
      */
     public function isIdempotent()
     {
@@ -67,13 +67,16 @@ public function isIdempotent()
     /**
      * Returns the default filename of this PIP.
      *
-     * @return      string
+     * @return string
      */
     public function getDefaultFilename()
     {
         return \call_user_func([$this->getDecoratedObject()->className, 'getDefaultFilename']);
     }
 
+    /**
+     * @return string
+     */
     public function getEffectiveDefaultFilename()
     {
         return './' . \preg_replace('~\.tar$~', '/', $this->getDefaultFilename());
@@ -82,7 +85,7 @@ public function getEffectiveDefaultFilename()
     /**
      * Returns true if the PIP exists, has a default filename and is idempotent.
      *
-     * @return      bool
+     * @return bool
      */
     public function isSupported()
     {
@@ -92,8 +95,8 @@ public function isSupported()
     /**
      * Returns `true` if this pip supports adding and editing entries via a gui.
      *
-     * @return  bool
-     * @since   5.2
+     * @return bool
+     * @since 5.2
      */
     public function supportsGui()
     {
@@ -103,6 +106,10 @@ public function supportsGui()
         );
     }
 
+    /**
+     * @param bool $toJson
+     * @return string|string[]
+     */
     public function getSyncDependencies($toJson = true)
     {
         $dependencies = \call_user_func([$this->getDecoratedObject()->className, 'getSyncDependencies']);
@@ -113,8 +120,8 @@ public function getSyncDependencies($toJson = true)
     /**
      * Returns the project this object belongs to.
      *
-     * @return  DevtoolsProject
-     * @since   5.2
+     * @return DevtoolsProject
+     * @since 5.2
      */
     public function getProject()
     {
@@ -125,7 +132,8 @@ public function getProject()
      * Sets the project this object belongs to.
      *
      * @param DevtoolsProject $project
-     * @since   5.2
+     * @return void
+     * @since 5.2
      */
     public function setProject(DevtoolsProject $project)
     {
@@ -137,8 +145,8 @@ public function setProject(DevtoolsProject $project)
      *
      * Note: No target will be set for the package installation plugin object.
      *
-     * @return  IPackageInstallationPlugin|IGuiPackageInstallationPlugin
-     * @since   5.2
+     * @return IPackageInstallationPlugin|IGuiPackageInstallationPlugin
+     * @since 5.2
      */
     public function getPip()
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPipEntryList.class.php b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPipEntryList.class.php
index 23fe80108ff..6d5a62c4139 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPipEntryList.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPipEntryList.class.php
@@ -15,14 +15,14 @@ class DevtoolsPipEntryList implements IDevtoolsPipEntryList
 {
     /**
      * pip entries
-     * @var array<array>
+     * @var array<string, array<string, mixed>>
      */
     protected $entries = [];
 
     /**
      * keys of the entries that can be used to display the entry list as a
      * table
-     * @var string[]
+     * @var array<string, string>
      */
     protected $keys;
 
@@ -146,10 +146,12 @@ public function setKeys(array $keys)
         }
 
         foreach ($keys as $key => $value) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_string($key)) {
                 throw new \InvalidArgumentException("Given key is no string, " . \gettype($key) . " given.");
             }
 
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_string($value)) {
                 throw new \InvalidArgumentException("Given value is no string, " . \gettype($value) . " given.");
             }
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/IDevtoolsPipEntryList.class.php b/wcfsetup/install/files/lib/system/devtools/pip/IDevtoolsPipEntryList.class.php
index 2bc281008d0..178aa45148b 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/IDevtoolsPipEntryList.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/IDevtoolsPipEntryList.class.php
@@ -18,8 +18,9 @@ interface IDevtoolsPipEntryList
      * Before adding entries, the keys must be set.
      *
      * @param string $id unique entry identifier
-     * @param array $entry entry data
-     * @throws  \BadMethodCallException     if no keys have been set
+     * @param array<string, mixed> $entry entry data
+     * @return void
+     * @throws \BadMethodCallException if no keys have been set
      */
     public function addEntry($id, array $entry);
 
@@ -32,16 +33,17 @@ public function addEntry($id, array $entry);
      *
      * Applying a second filter will filter the pre-filtered entries.
      *
-     * @param string|array $filter either a string that is used to search all entry elements or filter map `key => searchString`
+     * @param string|array<string, mixed> $filter either a string that is used to search all entry elements or filter map `key => searchString`
+     * @return void
      */
     public function filterEntries($filter);
 
     /**
      * Returns all entries in the list.
      *
-     * @param int $startIndex
-     * @param int $entryCount
-     * @return  array
+     * @param ?int $startIndex
+     * @param ?int $entryCount
+     * @return array<string, mixed>
      */
     public function getEntries($startIndex = null, $entryCount = null);
 
@@ -52,8 +54,8 @@ public function getEntries($startIndex = null, $entryCount = null);
      * The keys of the returned array are the entry keys and the array values are
      * language items describing the value.
      *
-     * @return  array
-     * @throws  \BadMethodCallException     if no keys have been set
+     * @return array<string, string>
+     * @throws \BadMethodCallException if no keys have been set
      */
     public function getKeys();
 
@@ -61,7 +63,7 @@ public function getKeys();
      * Returns true if an entry with the given entry identifier exists.
      *
      * @param string $id unique entry identifier
-     * @return  bool
+     * @return bool
      */
     public function hasEntry($id);
 
@@ -69,7 +71,8 @@ public function hasEntry($id);
      * Sets the keys of the entries that can be used to display the entry list
      * as a table.
      *
-     * @param array $keys entry keys
+     * @param array<string, string> $keys entry keys
+     * @return void
      */
     public function setKeys(array $keys);
 }
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/IGuiPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/devtools/pip/IGuiPackageInstallationPlugin.class.php
index 22eef3ae5ea..9c8cc6d60c6 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/IGuiPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/IGuiPackageInstallationPlugin.class.php
@@ -19,7 +19,7 @@ interface IGuiPackageInstallationPlugin extends IIdempotentPackageInstallationPl
      * Adds a new entry of this pip based on the data provided by the given
      * form.
      *
-     * @param IFormDocument $form
+     * @return void
      */
     public function addEntry(IFormDocument $form);
 
@@ -28,6 +28,7 @@ public function addEntry(IFormDocument $form);
      *
      * @param string $identifier identifier of deleted entry
      * @param bool $addDeleteInstruction if `true`, an explicit delete instruction is added
+     * @return void
      *
      * @throws  \InvalidArgumentException   if no such entry exists or delete instruction should be added but is not supported
      */
@@ -38,23 +39,22 @@ public function deleteEntry($identifier, $addDeleteInstruction);
      * provided by the given form and returns the new identifier of the entry
      * (or the old identifier if it has not changed).
      *
-     * @param IFormDocument $form
      * @param string $identifier
-     * @return  string          new identifier
+     * @return string new identifier
      */
     public function editEntry(IFormDocument $form, $identifier);
 
     /**
      * Returns additional template code for the form to add and edit entries.
      *
-     * @return  string
+     * @return string
      */
     public function getAdditionalTemplateCode();
 
     /**
      * Returns a list of all pip entries of this pip.
      *
-     * @return  IDevtoolsPipEntryList
+     * @return IDevtoolsPipEntryList
      */
     public function getEntryList();
 
@@ -63,8 +63,9 @@ public function getEntryList();
      * edit that entry has been submitted.
      *
      * @param string $identifier
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if no such entry exists
+     * @throws \InvalidArgumentException if no such entry exists
      */
     public function setEditedEntryIdentifier($identifier);
 
@@ -74,8 +75,7 @@ public function setEditedEntryIdentifier($identifier);
      * exists, `false` is returned.
      *
      * @param string $identifier
-     * @param IFormDocument $document
-     * @return  bool
+     * @return bool
      */
     public function setEntryData($identifier, IFormDocument $document);
 
@@ -86,7 +86,7 @@ public function setEntryData($identifier, IFormDocument $document);
      * For package installation plugins that support entries and categories
      * for these entries, `['entries', 'categories']` should be returned.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getEntryTypes();
 
@@ -94,7 +94,7 @@ public function getEntryTypes();
      * Populates the given form to be used for adding and editing entries
      * managed by this PIP.
      *
-     * @param IFormDocument $form
+     * @return void
      */
     public function populateForm(IFormDocument $form);
 
@@ -102,8 +102,9 @@ public function populateForm(IFormDocument $form);
      * Sets the type of the currently handled pip entries.
      *
      * @param string $entryType currently handled pip entry type
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if the given entry type is invalid (see `getEntryTypes()` method)
+     * @throws \InvalidArgumentException if the given entry type is invalid (see `getEntryTypes()` method)
      */
     public function setEntryType($entryType);
 
@@ -111,7 +112,7 @@ public function setEntryType($entryType);
      * Returns `true` if this package installation plugin supports delete
      * instructions.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsDeleteInstruction();
 }
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/TMultiXmlGuiPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/devtools/pip/TMultiXmlGuiPackageInstallationPlugin.class.php
index 23fb348285c..a8335a2849d 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/TMultiXmlGuiPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/TMultiXmlGuiPackageInstallationPlugin.class.php
@@ -38,6 +38,7 @@ trait TMultiXmlGuiPackageInstallationPlugin
      * form.
      *
      * @param IFormDocument $form
+     * @return void
      */
     public function addEntry(IFormDocument $form)
     {
@@ -53,9 +54,7 @@ public function addEntry(IFormDocument $form)
     /**
      * Creates a new XML element and insert it into the XML file.
      *
-     * @param XML $xml
-     * @param IFormDocument $form
-     * @return  \DOMElement
+     * @return \DOMElement
      */
     protected function createAndInsertNewXmlElement(XML $xml, IFormDocument $form)
     {
@@ -70,9 +69,8 @@ protected function createAndInsertNewXmlElement(XML $xml, IFormDocument $form)
      * provided by the given form and returns the new identifier of the entry
      * (or the old identifier if it has not changed).
      *
-     * @param IFormDocument $form
      * @param string $identifier
-     * @return  string          new identifier
+     * @return string new identifier
      */
     public function editEntry(IFormDocument $form, $identifier)
     {
@@ -96,10 +94,8 @@ public function editEntry(IFormDocument $form, $identifier)
     /**
      * Replaces an edited element with a new element and returns the new element.
      *
-     * @param XML $xml
-     * @param IFormDocument $form
      * @param string $identifier
-     * @return  \DOMElement
+     * @return \DOMElement
      */
     protected function replaceXmlElement(XML $xml, IFormDocument $form, $identifier)
     {
@@ -115,7 +111,7 @@ protected function replaceXmlElement(XML $xml, IFormDocument $form, $identifier)
     /**
      * Returns a list of all pip entries of this pip.
      *
-     * @return  IDevtoolsPipEntryList
+     * @return IDevtoolsPipEntryList
      */
     public function getEntryList()
     {
@@ -142,12 +138,13 @@ public function getEntryList()
      * Returns the xml objects for this pip.
      *
      * @param bool $createXmlFiles if `true` and if a relevant XML file does not exist, it is created
-     * @return  XML[]
+     * @return XML[]
      */
     abstract protected function getProjectXmls($createXmlFiles = false);
 
     /**
      * @inheritDoc
+     * @return void
      */
     public function setEditedEntryIdentifier($identifier)
     {
@@ -168,7 +165,8 @@ public function setEditedEntryIdentifier($identifier)
     }
 
     /**
-     * @inheritDoc
+     * @param string $identifier
+     * @return bool
      */
     public function setEntryData($identifier, IFormDocument $document)
     {
@@ -215,7 +213,9 @@ public function setEntryData($identifier, IFormDocument $document)
     }
 
     /**
-     * @inheritDoc
+     * @param string $identifier
+     * @param bool $addDeleteInstruction
+     * @return void
      */
     public function deleteEntry($identifier, $addDeleteInstruction)
     {
@@ -254,6 +254,7 @@ public function deleteEntry($identifier, $addDeleteInstruction)
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function deleteObject(\DOMElement $element)
     {
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/TXmlGuiPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/devtools/pip/TXmlGuiPackageInstallationPlugin.class.php
index 442b44f3c0d..d93e8df6260 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/TXmlGuiPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/TXmlGuiPackageInstallationPlugin.class.php
@@ -33,13 +33,13 @@ trait TXmlGuiPackageInstallationPlugin
 {
     /**
      * dom element representing the original data of the edited entry
-     * @var null|\DOMElement
+     * @var ?\DOMElement
      */
     protected $editedEntry;
 
     /**
      * type of the currently handled pip entries
-     * @var null|string
+     * @var ?string
      */
     protected $entryType;
 
@@ -48,6 +48,7 @@ trait TXmlGuiPackageInstallationPlugin
      * element.
      *
      * @param \DOMElement $element installation element
+     * @return void
      */
     protected function addDeleteElement(\DOMElement $element)
     {
@@ -60,14 +61,17 @@ protected function addDeleteElement(\DOMElement $element)
             $document->documentElement->appendChild($delete);
         }
 
-        $delete->appendChild($document->importNode($this->prepareDeleteXmlElement($element)));
+        $xmlElement = $this->prepareDeleteXmlElement($element);
+        // @phpstan-ignore function.impossibleType, notIdentical.alwaysFalse
+        \assert($xmlElement !== null);
+        $delete->appendChild($document->importNode($xmlElement));
     }
 
     /**
      * Adds a new entry of this pip based on the data provided by the given
      * form.
      *
-     * @param IFormDocument $form
+     * @return void
      */
     public function addEntry(IFormDocument $form)
     {
@@ -85,7 +89,7 @@ public function addEntry(IFormDocument $form)
     /**
      * Adds all fields to the given form to add or edit an entry.
      *
-     * @param IFormDocument $form
+     * @return void
      */
     abstract protected function addFormFields(IFormDocument $form);
 
@@ -94,8 +98,9 @@ abstract protected function addFormFields(IFormDocument $form);
      * child data and form.
      *
      * @param \DOMElement $element element to which the child elements are added
-     * @param array $children
+     * @param array<string|int, mixed> $children
      * @param IFormDocument $form form containing the children's data
+     * @return void
      */
     protected function appendElementChildren(\DOMElement $element, array $children, IFormDocument $form)
     {
@@ -142,9 +147,7 @@ protected function appendElementChildren(\DOMElement $element, array $children,
      * Creates a new XML element for the given document using the data provided
      * by the given form and return the new dom element.
      *
-     * @param \DOMDocument $document
-     * @param IFormDocument $form
-     * @return  \DOMElement
+     * @return \DOMElement
      */
     abstract protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form);
 
@@ -154,9 +157,7 @@ abstract protected function prepareXmlElement(\DOMDocument $document, IFormDocum
      *
      * This method internally calls `prepareXmlElement()` and fires an event.
      *
-     * @param \DOMDocument $document
-     * @param IFormDocument $form
-     * @return  \DOMElement
+     * @return \DOMElement
      */
     protected function createXmlElement(\DOMDocument $document, IFormDocument $form)
     {
@@ -183,6 +184,7 @@ protected function createXmlElement(\DOMDocument $document, IFormDocument $form)
      *
      * @param string $identifier
      * @param bool $addDeleteInstruction
+     * @return void
      */
     public function deleteEntry($identifier, $addDeleteInstruction)
     {
@@ -229,7 +231,7 @@ public function deleteEntry($identifier, $addDeleteInstruction)
      * because there is no content left.
      *
      * @param \DOMDocument $document sanitized document
-     * @return  bool
+     * @return bool
      */
     protected function sanitizeXmlFileAfterDeleteEntry(\DOMDocument $document)
     {
@@ -252,7 +254,7 @@ protected function sanitizeXmlFileAfterDeleteEntry(\DOMDocument $document)
     /**
      * Deletes the given element from database.
      *
-     * @param \DOMElement $element
+     * @return void
      */
     protected function deleteObject(\DOMElement $element)
     {
@@ -274,9 +276,8 @@ protected function deleteObject(\DOMElement $element)
      * provided by the given form and returns the new identifier of the entry
      * (or the old identifier if it has not changed).
      *
-     * @param IFormDocument $form
      * @param string $identifier
-     * @return  string          new identifier
+     * @return string new identifier
      */
     public function editEntry(IFormDocument $form, $identifier)
     {
@@ -300,7 +301,7 @@ public function editEntry(IFormDocument $form, $identifier)
     /**
      * Returns additional template code for the form to add and edit entries.
      *
-     * @return  string
+     * @return string
      */
     public function getAdditionalTemplateCode()
     {
@@ -312,7 +313,7 @@ public function getAdditionalTemplateCode()
      * if required.
      *
      * @param string $value
-     * @return  string
+     * @return string
      */
     protected function getAutoCdataValue($value)
     {
@@ -326,13 +327,13 @@ protected function getAutoCdataValue($value)
     /**
      * Returns the `import` element with the given identifier.
      *
-     * @param XML $xml
      * @param string $identifier
-     * @return  \DOMElement|null
+     * @return ?\DOMElement
      */
     protected function getElementByIdentifier(XML $xml, $identifier)
     {
         foreach ($this->getImportElements($xml->xpath()) as $element) {
+            // @phpstan-ignore function.alreadyNarrowedType, instanceof.alwaysTrue
             \assert($element instanceof \DOMElement);
             if ($this->getElementIdentifier($element) === $identifier) {
                 return $element;
@@ -347,7 +348,7 @@ protected function getElementByIdentifier(XML $xml, $identifier)
      *
      * @param \DOMElement $element element whose data is returned
      * @param bool $saveData is `true` if data is intended to be saved and otherwise `false`
-     * @return  array
+     * @return array<string, int|string>
      */
     abstract protected function fetchElementData(\DOMElement $element, $saveData);
 
@@ -357,7 +358,7 @@ abstract protected function fetchElementData(\DOMElement $element, $saveData);
      *
      * @param \DOMElement $element element whose data is returned
      * @param bool $saveData is `true` if data is intended to be saved and otherwise `false`
-     * @return  array
+     * @return mixed[]
      */
     protected function getElementData(\DOMElement $element, $saveData = false)
     {
@@ -381,8 +382,7 @@ protected function getElementData(\DOMElement $element, $saveData = false)
     /**
      * Returns the identifier of the given `import` element.
      *
-     * @param \DOMElement $element
-     * @return  string
+     * @return string
      */
     abstract protected function getElementIdentifier(\DOMElement $element);
 
@@ -391,7 +391,7 @@ abstract protected function getElementIdentifier(\DOMElement $element);
      * present for a new entry to be added as if it was added to an existing
      * file.
      *
-     * @return  string
+     * @return string
      */
     protected function getEmptyXml()
     {
@@ -409,7 +409,7 @@ protected function getEmptyXml()
      * Returns the name of the xsd file for this package installation plugin
      * (without the file extension).
      *
-     * @return  string
+     * @return string
      */
     protected function getXsdFilename()
     {
@@ -421,7 +421,7 @@ protected function getXsdFilename()
     /**
      * Returns a list of all pip entries of this pip.
      *
-     * @return  IDevtoolsPipEntryList
+     * @return IDevtoolsPipEntryList
      */
     public function getEntryList()
     {
@@ -450,7 +450,7 @@ public function getEntryList()
      * For package installation plugins that support entries and categories
      * for these entries, `['entries', 'categories']` should be returned.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getEntryTypes()
     {
@@ -460,7 +460,7 @@ public function getEntryTypes()
     /**
      * @inheritDoc
      *
-     * @return \DOMNodeList
+     * @return \DOMNodeList<\DOMElement>
      */
     protected function getImportElements(\DOMXPath $xpath)
     {
@@ -480,7 +480,7 @@ protected function getImportElements(\DOMXPath $xpath)
     /**
      * Returns the xml object for this pip.
      *
-     * @return  XML
+     * @return XML
      */
     protected function getProjectXml()
     {
@@ -499,7 +499,7 @@ protected function getProjectXml()
     /**
      * Returns the location of the xml file for this pip.
      *
-     * @return  string
+     * @return string
      */
     protected function getXmlFileLocation()
     {
@@ -514,6 +514,7 @@ protected function getXmlFileLocation()
      *
      * @param XML $xml XML document to which the element is added
      * @param \DOMElement $newElement added new element
+     * @return void
      */
     protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
     {
@@ -533,7 +534,7 @@ protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
      * Populates the given form to be used for adding and editing entries
      * managed by this PIP.
      *
-     * @param IFormDocument $form
+     * @return void
      */
     public function populateForm(IFormDocument $form)
     {
@@ -558,8 +559,7 @@ public function populateForm(IFormDocument $form)
     /**
      * Returns a delete xml element based on the given import element.
      *
-     * @param \DOMElement $element
-     * @return  \DOMElement
+     * @return ?\DOMElement
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
     {
@@ -593,6 +593,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
      *
      * @param \DOMElement $newElement XML element with new data
      * @param \DOMElement|null $oldElement XML element with old data
+     * @return void
      */
     protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement = null)
     {
@@ -630,8 +631,9 @@ protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement
      * edit that entry has been submitted.
      *
      * @param string $identifier
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if no such entry exists
+     * @throws \InvalidArgumentException if no such entry exists
      */
     public function setEditedEntryIdentifier($identifier)
     {
@@ -648,8 +650,7 @@ public function setEditedEntryIdentifier($identifier)
      * exists, `false` is returned.
      *
      * @param string $identifier
-     * @param IFormDocument $document
-     * @return  bool
+     * @return bool
      */
     public function setEntryData($identifier, IFormDocument $document)
     {
@@ -692,7 +693,7 @@ public function setEntryData($identifier, IFormDocument $document)
     /**
      * Sets the keys of the given (empty) entry list.
      *
-     * @param IDevtoolsPipEntryList $entryList
+     * @return void
      */
     abstract protected function setEntryListKeys(IDevtoolsPipEntryList $entryList);
 
@@ -700,8 +701,9 @@ abstract protected function setEntryListKeys(IDevtoolsPipEntryList $entryList);
      * Sets the type of the currently handled pip entries.
      *
      * @param string $entryType currently handled pip entry type
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if the given entry type is invalid (see `getEntryTypes()` method)
+     * @throws \InvalidArgumentException if the given entry type is invalid (see `getEntryTypes()` method)
      */
     public function setEntryType($entryType)
     {
@@ -716,7 +718,7 @@ public function setEntryType($entryType)
      * Returns `true` if this package installation plugin supports delete
      * instructions.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsDeleteInstruction()
     {
diff --git a/wcfsetup/install/files/lib/system/edit/EditHistoryManager.class.php b/wcfsetup/install/files/lib/system/edit/EditHistoryManager.class.php
index 8419fd515fc..b2f5e6fd9c4 100644
--- a/wcfsetup/install/files/lib/system/edit/EditHistoryManager.class.php
+++ b/wcfsetup/install/files/lib/system/edit/EditHistoryManager.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\edit;
 
 use wcf\data\edit\history\entry\EditHistoryEntryList;
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\exception\SystemException;
@@ -20,7 +21,7 @@ class EditHistoryManager extends SingletonFactory
 {
     /**
      * list of available object types
-     * @var array
+     * @var array<string, ObjectType>
      */
     protected $availableObjectTypes = [];
 
@@ -38,8 +39,8 @@ protected function init()
      * Returns the id of the object type with the given name.
      *
      * @param string $objectType
-     * @return  int
-     * @throws  SystemException
+     * @return int
+     * @throws SystemException
      */
     public function getObjectTypeID($objectType)
     {
@@ -61,6 +62,7 @@ public function getObjectTypeID($objectType)
      * @param string $username
      * @param string $editReason
      * @param int $obsoletedByUserID The userID of the user that forced this entry to become outdated
+     * @return void
      */
     public function add($objectType, $objectID, $message, $time, $userID, $username, $editReason, $obsoletedByUserID)
     {
@@ -92,6 +94,7 @@ public function add($objectType, $objectID, $message, $time, $userID, $username,
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public function delete($objectType, array $objectIDs)
     {
@@ -121,6 +124,7 @@ public function delete($objectType, array $objectIDs)
      *
      * @param int[] $userIDs
      * @param int $timeframe
+     * @return void
      */
     public function bulkRevert(array $userIDs, $timeframe = 86400)
     {
diff --git a/wcfsetup/install/files/lib/system/edit/IHistorySavingObject.class.php b/wcfsetup/install/files/lib/system/edit/IHistorySavingObject.class.php
index 6fe0752d5e2..a8855b332f8 100644
--- a/wcfsetup/install/files/lib/system/edit/IHistorySavingObject.class.php
+++ b/wcfsetup/install/files/lib/system/edit/IHistorySavingObject.class.php
@@ -18,14 +18,14 @@ interface IHistorySavingObject extends IDatabaseObjectProcessor, IUserContent
     /**
      * Returns the object's current edit reason.
      *
-     * @return  string
+     * @return string
      */
     public function getEditReason();
 
     /**
      * Returns the object's current message text.
      *
-     * @return  string
+     * @return string
      */
     public function getMessage();
 
@@ -33,11 +33,14 @@ public function getMessage();
      * Reverts the object's text to the given EditHistoryEntry.
      *
      * @param EditHistoryEntry $edit
+     * @return void
      */
     public function revertVersion(EditHistoryEntry $edit);
 
     /**
      * Sets the page location data.
+     *
+     * @return void
      */
     public function setLocation();
 }
diff --git a/wcfsetup/install/files/lib/system/edit/IHistorySavingObjectTypeProvider.class.php b/wcfsetup/install/files/lib/system/edit/IHistorySavingObjectTypeProvider.class.php
index bb537ff5ebe..b7f577f5605 100644
--- a/wcfsetup/install/files/lib/system/edit/IHistorySavingObjectTypeProvider.class.php
+++ b/wcfsetup/install/files/lib/system/edit/IHistorySavingObjectTypeProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\edit;
 
+use wcf\data\DatabaseObject;
 use wcf\data\object\type\IObjectTypeProvider;
 use wcf\system\exception\PermissionDeniedException;
 
@@ -11,6 +12,9 @@
  * @author  Tim Duesterhus
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends IObjectTypeProvider<DatabaseObject>
  */
 interface IHistorySavingObjectTypeProvider extends IObjectTypeProvider
 {
@@ -19,6 +23,7 @@ interface IHistorySavingObjectTypeProvider extends IObjectTypeProvider
      * older version of the given IHistorySavingObject.
      *
      * @param IHistorySavingObject $object
+     * @return void
      * @throws  PermissionDeniedException   if access is denied
      * @throws  \InvalidArgumentException   if given object has not be provided by this provider and thus cannot be checked by this method
      */
@@ -27,7 +32,7 @@ public function checkPermissions(IHistorySavingObject $object);
     /**
      * Returns the identifier of the appropriate page menu item.
      *
-     * @return  string
+     * @return string
      * @deprecated  3.0
      */
     public function getActivePageMenuItem();
diff --git a/wcfsetup/install/files/lib/system/email/Email.class.php b/wcfsetup/install/files/lib/system/email/Email.class.php
index 9ded95afa5e..b77024a2e78 100644
--- a/wcfsetup/install/files/lib/system/email/Email.class.php
+++ b/wcfsetup/install/files/lib/system/email/Email.class.php
@@ -19,6 +19,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ * @phpstan-type Recipient array{type: string, mailbox: Mailbox}
  */
 class Email
 {
@@ -36,7 +37,7 @@ class Email
 
     /**
      * Recipients of this email.
-     * @var array
+     * @var array<string, Recipient>
      */
     protected $recipients = [];
 
@@ -100,7 +101,7 @@ class Email
 
     /**
      * User specified X-* headers
-     * @var array
+     * @var list<array{0: string, 1: string}>
      */
     protected $extraHeaders = [];
 
@@ -119,7 +120,7 @@ class Email
     /**
      * Returns the mail host for use in the Message-Id.
      *
-     * @return  string
+     * @return string
      */
     public static function getHost()
     {
@@ -134,6 +135,7 @@ public static function getHost()
      * Sets the email's 'Subject'.
      *
      * @param string $subject
+     * @return void
      */
     public function setSubject($subject)
     {
@@ -143,7 +145,7 @@ public function setSubject($subject)
     /**
      * Returns the email's 'Subject'.
      *
-     * @return  string
+     * @return string
      */
     public function getSubject()
     {
@@ -154,6 +156,7 @@ public function getSubject()
      * Sets the email's 'Date'.
      *
      * @param \DateTime $date
+     * @return void
      */
     public function setDate(?\DateTime $date = null)
     {
@@ -164,7 +167,7 @@ public function setDate(?\DateTime $date = null)
      * Returns the email's 'Date'.
      * If no header is set yet the current time will automatically be set.
      *
-     * @return  \DateTime
+     * @return \DateTime
      */
     public function getDate()
     {
@@ -179,7 +182,8 @@ public function getDate()
      * Sets the part left of the at sign (@) in the email's 'Message-Id'.
      *
      * @param string $messageID
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      */
     public function setMessageID($messageID = null)
     {
@@ -205,7 +209,7 @@ public function setMessageID($messageID = null)
      * Returns the email's full 'Message-Id' including the host.
      * If no header is set yet a message id will automatically be generated and set.
      *
-     * @return  string
+     * @return string
      */
     public function getMessageID()
     {
@@ -220,7 +224,8 @@ public function getMessageID()
      * Adds a message id to the email's 'In-Reply-To'.
      *
      * @param string $messageID
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      */
     public function addInReplyTo($messageID)
     {
@@ -235,6 +240,7 @@ public function addInReplyTo($messageID)
      * Removes a message id from the email's 'In-Reply-To'.
      *
      * @param string $messageID
+     * @return void
      */
     public function removeInReplyTo($messageID)
     {
@@ -244,7 +250,7 @@ public function removeInReplyTo($messageID)
     /**
      * Returns the email's 'In-Reply-To' message ids.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getInReplyTo()
     {
@@ -255,7 +261,8 @@ public function getInReplyTo()
      * Adds a message id to the email's 'References'.
      *
      * @param string $messageID
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      */
     public function addReferences($messageID)
     {
@@ -270,6 +277,7 @@ public function addReferences($messageID)
      * Removes a message id from the email's 'References'.
      *
      * @param string $messageID
+     * @return void
      */
     public function removeReferences($messageID)
     {
@@ -279,7 +287,7 @@ public function removeReferences($messageID)
     /**
      * Returns the email's 'References' message ids.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getReferences()
     {
@@ -291,7 +299,8 @@ public function getReferences()
      *
      * @param ?string $listId
      * @param string $humanReadable
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      * @since 5.3
      */
     public function setListID($listId, $humanReadable = null)
@@ -325,7 +334,7 @@ public function setListID($listId, $humanReadable = null)
      * Returns the email's full 'List-Id' including the host. Returns 'null'
      * if no 'List-Id' is set.
      *
-     * @return  ?string
+     * @return ?string
      * @since 5.3
      */
     public function getListID()
@@ -345,6 +354,7 @@ public function getListID()
      *
      * @param ?string $uri
      * @param bool $supportsOneClick
+     * @return void
      * @since 5.3
      */
     public function setListUnsubscribe($uri, $supportsOneClick = false)
@@ -363,7 +373,7 @@ public function setListUnsubscribe($uri, $supportsOneClick = false)
      * Returns the email's full 'List-Id' including the host. Returns 'null'
      * if no 'List-Id' is set.
      *
-     * @return  ?string
+     * @return ?string
      * @since 5.3
      */
     public function getListUnsubscribeUri()
@@ -375,6 +385,7 @@ public function getListUnsubscribeUri()
      * Sets the email's 'From'.
      *
      * @param Mailbox $sender
+     * @return void
      */
     public function setSender(?Mailbox $sender = null)
     {
@@ -385,7 +396,7 @@ public function setSender(?Mailbox $sender = null)
      * Returns the email's 'From'.
      * If no header is set yet the MAIL_FROM_ADDRESS will automatically be set.
      *
-     * @return  Mailbox
+     * @return Mailbox
      */
     public function getSender()
     {
@@ -400,6 +411,7 @@ public function getSender()
      * Sets the email's 'Reply-To'.
      *
      * @param Mailbox $replyTo
+     * @return void
      */
     public function setReplyTo(?Mailbox $replyTo = null)
     {
@@ -410,7 +422,7 @@ public function setReplyTo(?Mailbox $replyTo = null)
      * Returns the email's 'Reply-To'.
      * If no header is set yet the MAIL_ADMIN_ADDRESS will automatically be set.
      *
-     * @return  Mailbox
+     * @return Mailbox
      */
     public function getReplyTo()
     {
@@ -426,7 +438,8 @@ public function getReplyTo()
      *
      * @param Mailbox $recipient
      * @param string $type One of 'to', 'cc', 'bcc'
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      */
     public function addRecipient(Mailbox $recipient, $type = 'to')
     {
@@ -455,6 +468,7 @@ public function addRecipient(Mailbox $recipient, $type = 'to')
      * Removes a recipient from this email.
      *
      * @param Mailbox $recipient
+     * @return void
      */
     public function removeRecipient(Mailbox $recipient)
     {
@@ -464,7 +478,7 @@ public function removeRecipient(Mailbox $recipient)
     /**
      * Returns the email's recipients as an array of [ $recipient, $type ] tuples.
      *
-     * @return  array
+     * @return array<string, Recipient>
      */
     public function getRecipients()
     {
@@ -476,7 +490,8 @@ public function getRecipients()
      *
      * @param string $header
      * @param string $value
-     * @throws  \DomainException
+     * @return void
+     * @throws \DomainException
      */
     public function addHeader($header, $value)
     {
@@ -495,8 +510,8 @@ public function addHeader($header, $value)
      * Note: You must have set a Subject and at least one recipient, otherwise fetching the
      *       headers will fail.
      *
-     * @return  array
-     * @throws  \LogicException
+     * @return list<array{0: string, 1: string}>
+     * @throws \LogicException
      */
     public function getHeaders()
     {
@@ -593,7 +608,7 @@ public static function getCanonicalHeaderName(string $name): string
      * Returns the email's headers as a string. Returns the header names in their
      * canonical form.
      *
-     * @return  string
+     * @return string
      * @see Email::getHeaders()
      * @see Email::getCanonicalHeaderName()
      */
@@ -612,6 +627,7 @@ public function getHeaderString()
      * Sets the body of this email.
      *
      * @param AbstractMimePart $body
+     * @return void
      */
     public function setBody(AbstractMimePart $body)
     {
@@ -704,6 +720,7 @@ public function getJobs()
      * Queues this email for delivery.
      * This is equivalent to manually queuing the jobs returned by getJobs().
      *
+     * @return void
      * @see \wcf\system\email\Email::getJobs()
      * @see \wcf\system\background\BackgroundQueueHandler::enqueueIn()
      */
diff --git a/wcfsetup/install/files/lib/system/email/SimpleEmail.class.php b/wcfsetup/install/files/lib/system/email/SimpleEmail.class.php
index 27a56668997..8769511ccef 100644
--- a/wcfsetup/install/files/lib/system/email/SimpleEmail.class.php
+++ b/wcfsetup/install/files/lib/system/email/SimpleEmail.class.php
@@ -47,6 +47,7 @@ public function __construct()
      * Sets the email's 'Subject'.
      *
      * @param string $subject
+     * @return void
      * @see Email::setSubject()
      */
     public function setSubject($subject)
@@ -60,6 +61,7 @@ public function setSubject($subject)
      * the email.
      *
      * @param User $user
+     * @return void
      */
     public function setRecipient(User $user)
     {
@@ -80,7 +82,8 @@ public function setRecipient(User $user)
      * An empty string clears this version (not recommended!).
      *
      * @param string $message
-     * @see     PlainTextMimePart
+     * @return void
+     * @see PlainTextMimePart
      */
     public function setMessage($message)
     {
@@ -94,7 +97,8 @@ public function setMessage($message)
      * An empty string clears this version.
      *
      * @param string $message
-     * @see     HtmlTextMimePart
+     * @return void
+     * @see HtmlTextMimePart
      */
     public function setHtmlMessage($message)
     {
@@ -106,7 +110,7 @@ public function setHtmlMessage($message)
     /**
      * Sets the proper email body based on $textHtml and $textPlain.
      */
-    private function fixBody()
+    private function fixBody(): void
     {
         $parts = [];
         if ($this->textHtml) {
@@ -132,6 +136,7 @@ public function setMessageID(?string $messageId): void
     /**
      * Queues this email for delivery.
      *
+     * @return void
      * @see Email::send()
      */
     public function send()
diff --git a/wcfsetup/install/files/lib/system/email/mime/AbstractMimePart.class.php b/wcfsetup/install/files/lib/system/email/mime/AbstractMimePart.class.php
index 66979b603b6..69243fea55e 100644
--- a/wcfsetup/install/files/lib/system/email/mime/AbstractMimePart.class.php
+++ b/wcfsetup/install/files/lib/system/email/mime/AbstractMimePart.class.php
@@ -40,7 +40,7 @@ abstract public function getContentTransferEncoding();
      *
      * This method must be idempotent.
      *
-     * @return  array
+     * @return list<array{0: string, 1: string}>
      */
     public function getAdditionalHeaders()
     {
diff --git a/wcfsetup/install/files/lib/system/email/mime/AbstractMultipartMimePart.class.php b/wcfsetup/install/files/lib/system/email/mime/AbstractMultipartMimePart.class.php
index d8d2e326726..82d096fe1c6 100644
--- a/wcfsetup/install/files/lib/system/email/mime/AbstractMultipartMimePart.class.php
+++ b/wcfsetup/install/files/lib/system/email/mime/AbstractMultipartMimePart.class.php
@@ -24,7 +24,7 @@ abstract class AbstractMultipartMimePart extends AbstractMimePart implements IRe
 
     /**
      * The parts.
-     * @var \SplObjectStorage
+     * @var \SplObjectStorage<AbstractMimePart, mixed>
      */
     protected $parts;
 
@@ -60,8 +60,8 @@ public function setRecipient(?Mailbox $mailbox = null)
     /**
      * Concatenates the given mime parts.
      *
-     * @param \Traversable $parts
-     * @return  string
+     * @param \Traversable<int, AbstractMimePart> $parts
+     * @return string
      */
     protected function getConcatenatedParts($parts)
     {
@@ -125,8 +125,9 @@ public function getContent()
      *
      * @param AbstractMimePart $part
      * @param mixed $data Additional data, to be defined by child classes
-     * @throws  \InvalidArgumentException
-     * @throws  \DomainException
+     * @return void
+     * @throws \InvalidArgumentException
+     * @throws \DomainException
      */
     public function addMimePart(AbstractMimePart $part, $data = null)
     {
@@ -162,6 +163,7 @@ public function addMimePart(AbstractMimePart $part, $data = null)
      * Removes a mime part from this multipart part.
      *
      * @param AbstractMimePart $part
+     * @return void
      */
     public function removeMimePart(AbstractMimePart $part)
     {
@@ -173,7 +175,7 @@ public function removeMimePart(AbstractMimePart $part)
      * Note: The returned \SplObjectStorage is a clone of the internal one.
      * Modifications will not reflect on this object.
      *
-     * @return  \SplObjectStorage
+     * @return \SplObjectStorage<AbstractMimePart, mixed>
      */
     public function getMimeParts()
     {
diff --git a/wcfsetup/install/files/lib/system/email/mime/IRecipientAwareMimePart.class.php b/wcfsetup/install/files/lib/system/email/mime/IRecipientAwareMimePart.class.php
index e37c2a422cb..025773099d0 100644
--- a/wcfsetup/install/files/lib/system/email/mime/IRecipientAwareMimePart.class.php
+++ b/wcfsetup/install/files/lib/system/email/mime/IRecipientAwareMimePart.class.php
@@ -19,7 +19,8 @@ interface IRecipientAwareMimePart
      * Note: `null` is a valid parameter and denotes that this mime part should
      * not be individualized.
      *
-     * @param Mailbox $mailbox
+     * @param ?Mailbox $mailbox
+     * @return void
      */
     public function setRecipient(?Mailbox $mailbox = null);
 }
diff --git a/wcfsetup/install/files/lib/system/email/mime/MultipartAlternativeMimePart.class.php b/wcfsetup/install/files/lib/system/email/mime/MultipartAlternativeMimePart.class.php
index 5c8b26b813c..1d6dbba62e7 100644
--- a/wcfsetup/install/files/lib/system/email/mime/MultipartAlternativeMimePart.class.php
+++ b/wcfsetup/install/files/lib/system/email/mime/MultipartAlternativeMimePart.class.php
@@ -25,13 +25,17 @@ public function getContentType()
      */
     protected function getConcatenatedParts($parts)
     {
-        /** @var \SplObjectStorage $parts */
+        \assert($parts instanceof \SplObjectStorage);
 
+        /** @var \SplPriorityQueue<int, AbstractMimePart> */
         $sortedParts = new \SplPriorityQueue();
 
         $parts->rewind();
         while ($parts->valid()) {
-            $sortedParts->insert($parts->current(), \PHP_INT_MAX - $parts->getInfo());
+            $part = $parts->current();
+            \assert($part instanceof AbstractMimePart);
+
+            $sortedParts->insert($part, \PHP_INT_MAX - $parts->getInfo());
             $parts->next();
         }
 
diff --git a/wcfsetup/install/files/lib/system/email/mime/MultipartMixedMimePart.class.php b/wcfsetup/install/files/lib/system/email/mime/MultipartMixedMimePart.class.php
index 2ebf96c2713..4210624c3e3 100644
--- a/wcfsetup/install/files/lib/system/email/mime/MultipartMixedMimePart.class.php
+++ b/wcfsetup/install/files/lib/system/email/mime/MultipartMixedMimePart.class.php
@@ -27,8 +27,8 @@ public function getContentType()
      *
      * @param AbstractMimePart $part
      * @param mixed $data Ignored.
-     * @throws  \InvalidArgumentException
-     * @throws  \DomainException
+     * @throws \InvalidArgumentException
+     * @throws \DomainException
      */
     // @codingStandardsIgnoreStart
     public function addMimePart(AbstractMimePart $part, $data = null)
diff --git a/wcfsetup/install/files/lib/system/email/transport/DebugEmailTransport.class.php b/wcfsetup/install/files/lib/system/email/transport/DebugEmailTransport.class.php
index 2e67628c3d7..6921cd88dfc 100644
--- a/wcfsetup/install/files/lib/system/email/transport/DebugEmailTransport.class.php
+++ b/wcfsetup/install/files/lib/system/email/transport/DebugEmailTransport.class.php
@@ -19,7 +19,7 @@
  */
 final class DebugEmailTransport implements IEmailTransport
 {
-    protected StreamInterface $mbox;
+    private readonly StreamInterface $mbox;
 
     /**
      * Creates a new DebugTransport using the given mbox as target.
@@ -38,7 +38,7 @@ public function __construct(?string $mbox = null)
     /**
      * Writes the given $email into the mbox.
      */
-    public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo)
+    public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo): void
     {
         $this->mbox->write(\sprintf(
             "From %s %s\r\n",
diff --git a/wcfsetup/install/files/lib/system/email/transport/IEmailTransport.class.php b/wcfsetup/install/files/lib/system/email/transport/IEmailTransport.class.php
index ea7842c6774..8ce07687841 100644
--- a/wcfsetup/install/files/lib/system/email/transport/IEmailTransport.class.php
+++ b/wcfsetup/install/files/lib/system/email/transport/IEmailTransport.class.php
@@ -21,6 +21,7 @@ interface IEmailTransport
      * @param Email $email
      * @param Mailbox $envelopeFrom
      * @param Mailbox $envelopeTo
+     * @return mixed
      */
     public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo);
 }
diff --git a/wcfsetup/install/files/lib/system/email/transport/PhpEmailTransport.class.php b/wcfsetup/install/files/lib/system/email/transport/PhpEmailTransport.class.php
index 07f375f521b..21f5ced26d0 100644
--- a/wcfsetup/install/files/lib/system/email/transport/PhpEmailTransport.class.php
+++ b/wcfsetup/install/files/lib/system/email/transport/PhpEmailTransport.class.php
@@ -23,7 +23,7 @@ final class PhpEmailTransport implements IEmailTransport
      *
      * @throws  TransientFailure
      */
-    public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo)
+    public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo): void
     {
         $headers = \array_filter($email->getHeaders(), static function ($item) {
             // filter out headers that are either
diff --git a/wcfsetup/install/files/lib/system/email/transport/SmtpEmailTransport.class.php b/wcfsetup/install/files/lib/system/email/transport/SmtpEmailTransport.class.php
index 53b188890d4..dc0f0a67acb 100644
--- a/wcfsetup/install/files/lib/system/email/transport/SmtpEmailTransport.class.php
+++ b/wcfsetup/install/files/lib/system/email/transport/SmtpEmailTransport.class.php
@@ -23,58 +23,50 @@ final class SmtpEmailTransport implements IStatusReportingEmailTransport
 {
     /**
      * SMTP connection
-     * @var ?RemoteFile
      */
-    protected $connection;
+    private ?RemoteFile $connection = null;
 
     /**
      * host of the smtp server to use
-     * @var ?string
      */
-    protected $host;
+    private readonly string $host;
 
     /**
      * port to use
-     * @var ?int
      */
-    protected $port;
+    private readonly int $port;
 
     /**
      * username to use for authentication
-     * @var ?string
      */
-    protected $username;
+    private readonly string $username;
 
     /**
      * password corresponding to the username
-     * @var ?string
      */
-    protected $password;
+    private readonly string $password;
 
     /**
      * STARTTLS encryption level
-     * @var ?string
      */
-    protected $starttls;
+    private readonly string $starttls;
 
     /**
      * last value written to the server
-     * @var string
      */
-    protected $lastWrite = '';
+    private string $lastWrite = '';
 
     /**
      * ESMTP features advertised by the server
      * @var string[]
      */
-    protected $features = [];
+    private array $features = [];
 
     /**
      * if this property is an instance of \Exception email delivery will be locked
      * and the \Exception will be thrown when attempting to deliver() an email
-     * @var ?\Exception
      */
-    protected $locked;
+    private ?\Exception $locked = null;
 
     /**
      * Creates a new SmtpEmailTransport using the given host.
@@ -123,10 +115,8 @@ public function __destruct()
      * Tests the connection by establishing a connection and optionally
      * providing user credentials. Returns the error message or an empty
      * string on success.
-     *
-     * @return      string
      */
-    public function testConnection()
+    public function testConnection(): string
     {
         try {
             $this->connect(10);
@@ -165,11 +155,11 @@ public function testConnection()
      * Returns a tuple [ status code, reply text ].
      *
      * @param int[] $expectedCodes
-     * @return  array
-     * @throws  PermanentFailure
-     * @throws  TransientFailure
+     * @return array{0: ?int, 1: string}
+     * @throws PermanentFailure
+     * @throws TransientFailure
      */
-    protected function read(array $expectedCodes)
+    protected function read(array $expectedCodes): array
     {
         $truncateReply = static function ($reply) {
             return StringUtil::truncate(
@@ -283,10 +273,8 @@ protected function read(array $expectedCodes)
 
     /**
      * Writes the given line to the server.
-     *
-     * @param string $data
      */
-    protected function write($data)
+    private function write(string $data): void
     {
         $this->lastWrite = $data;
         $this->connection->write($data . "\r\n");
@@ -296,10 +284,9 @@ protected function write($data)
      * Connects to the server and enables STARTTLS if available. Bails
      * out if STARTTLS is not available and connection is set to 'encrypt'.
      *
-     * @param int $overrideTimeout
-     * @throws  PermanentFailure
+     * @throws PermanentFailure
      */
-    protected function connect($overrideTimeout = null)
+    private function connect(?int $overrideTimeout = null): void
     {
         if ($overrideTimeout === null) {
             $this->connection = new RemoteFile($this->host, $this->port);
@@ -354,9 +341,9 @@ protected function connect($overrideTimeout = null)
     /**
      * Enables STARTTLS on the connection.
      *
-     * @throws  TransientFailure
+     * @throws TransientFailure
      */
-    protected function starttls()
+    private function starttls(): void
     {
         $this->write("STARTTLS");
         $this->read([220]);
@@ -374,7 +361,7 @@ protected function starttls()
      * Performs SASL authentication using the credentials provided in the
      * constructor. Supported mechanisms are LOGIN and PLAIN.
      */
-    protected function auth()
+    private function auth(): void
     {
         if (!$this->username || !$this->password) {
             return;
@@ -443,7 +430,7 @@ protected function auth()
     /**
      * Cleanly closes the connection to the server.
      */
-    protected function disconnect()
+    private function disconnect(): void
     {
         if ($this->connection) {
             try {
@@ -460,8 +447,8 @@ protected function disconnect()
     /**
      * Delivers the given email using SMTP.
      *
-     * @throws  \Exception
-     * @throws  PermanentFailure
+     * @throws \Exception
+     * @throws PermanentFailure
      */
     public function deliver(Email $email, Mailbox $envelopeFrom, Mailbox $envelopeTo): string
     {
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/comments/RenderComment.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/comments/RenderComment.class.php
index 220708d48ef..468fb674c01 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/comments/RenderComment.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/comments/RenderComment.class.php
@@ -91,7 +91,7 @@ private function assertResponseIsAccessible(Comment $comment, CommentResponse $r
         }
     }
 
-    private function markNotificationsAsRead(Comment $comment, ?CommentResponse $response = null)
+    private function markNotificationsAsRead(Comment $comment, ?CommentResponse $response = null): void
     {
         $objectType = CommentHandler::getInstance()->getObjectType($comment->objectTypeID)->objectType;
         if ($response === null) {
@@ -107,6 +107,12 @@ private function markNotificationsAsRead(Comment $comment, ?CommentResponse $res
         }
     }
 
+    /**
+     * @return array{
+     *  template: string,
+     *  response?: string,
+     * }
+     */
     private function renderComment(Comment $comment, ?CommentResponse $response = null, bool $messageOnly = false): array
     {
         if ($comment->hasEmbeddedObjects) {
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/exceptions/RenderException.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/exceptions/RenderException.class.php
index 553dae1cc55..e786268b1bd 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/exceptions/RenderException.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/exceptions/RenderException.class.php
@@ -50,6 +50,9 @@ private function assertExceptionLogIsAccessible(): void
         }
     }
 
+    /**
+     * @return ?mixed[]
+     */
     private function getException(string $exceptionID): ?array
     {
         $logFile = $this->getLogFile($exceptionID);
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/languages/items/DeleteItem.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/languages/items/DeleteItem.class.php
index 94a38b6e281..93414af376c 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/languages/items/DeleteItem.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/languages/items/DeleteItem.class.php
@@ -50,6 +50,9 @@ private function assertLanguageItemCanBeDeleted(LanguageItem $option): void
         }
     }
 
+    /**
+     * @return array<int, LanguageItem>
+     */
     private function getLanguageItemsForAllLanguages(LanguageItem $languageItem): array
     {
         $languageItemList = new LanguageItemList();
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/GetMessageAuthor.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/GetMessageAuthor.class.php
index 3c080233bfe..937b2e47d9b 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/GetMessageAuthor.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/GetMessageAuthor.class.php
@@ -28,6 +28,7 @@ public function __invoke(ServerRequestInterface $request, array $variables): Res
     {
         $parameters = Helper::mapApiParameters($request, GetMessageAuthorParameters::class);
 
+        // @phpstan-ignore argument.templateType
         $object = Helper::fetchObjectFromRequestParameter($parameters->objectID, $parameters->className);
         \assert($object instanceof IMessage && $object instanceof DatabaseObject);
 
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/RenderQuote.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/RenderQuote.class.php
index 4858d1fe85b..b53641e5004 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/RenderQuote.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/messages/RenderQuote.class.php
@@ -31,6 +31,7 @@ public function __invoke(ServerRequestInterface $request, array $variables): Res
     {
         $parameters = Helper::mapApiParameters($request, GetRenderQuoteParameters::class);
 
+        // @phpstan-ignore argument.templateType
         $object = Helper::fetchObjectFromRequestParameter($parameters->objectID, $parameters->className);
         \assert($object instanceof IMessage && $object instanceof DatabaseObject);
 
diff --git a/wcfsetup/install/files/lib/system/event/EventHandler.class.php b/wcfsetup/install/files/lib/system/event/EventHandler.class.php
index 4c5440fce29..2cc00204fdc 100644
--- a/wcfsetup/install/files/lib/system/event/EventHandler.class.php
+++ b/wcfsetup/install/files/lib/system/event/EventHandler.class.php
@@ -15,7 +15,6 @@
  * @author  Tim Duesterhus, Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
- * @template T of object
  */
 final class EventHandler extends SingletonFactory
 {
@@ -35,7 +34,7 @@ final class EventHandler extends SingletonFactory
     private array $inheritedActions = [];
 
     /**
-     * @var array<string, array<class-string<T>, T>>
+     * @var array<string, array<class-string<object>, object>>
      */
     private array $actionsObjects = [];
 
@@ -45,7 +44,7 @@ final class EventHandler extends SingletonFactory
     private array $inheritedActionsObjects = [];
 
     /**
-     * @var array<class-string<T>, T>
+     * @var array<class-string<object>, object>
      */
     private array $listenerObjects = [];
 
@@ -77,9 +76,9 @@ protected function init(): void
     /**
      * Executes all inherited listeners for the given event.
      *
-     * @param mixed $eventObj
+     * @param mixed[] $parameters
      */
-    private function executeInheritedActions($eventObj, string $eventName, string $className, string $name, array &$parameters)
+    private function executeInheritedActions(mixed $eventObj, string $eventName, string $className, string $name, array &$parameters): void
     {
         // create objects of the actions
         if (!isset($this->inheritedActionsObjects[$name])) {
@@ -140,11 +139,12 @@ private function getListenerObject(string $className): object
 
     /**
      * @param   (callable[])|((IParameterizedEventListener|ILegacyEventListener)[])     $eventListeners
+     * @param mixed[] $parameters
      * @since   5.5
      */
     private function executeListeners(
         array $eventListeners,
-        $eventObj,
+        mixed $eventObj,
         string $className,
         string $eventName,
         array &$parameters
@@ -180,9 +180,9 @@ private function executeListeners(
      * the next event listener and be available after execution of every
      * event listener.
      *
-     * @param mixed $eventObj
+     * @param mixed[] $parameters
      */
-    public function fireAction($eventObj, string $eventName, array &$parameters = [])
+    public function fireAction(mixed $eventObj, string $eventName, array &$parameters = []): void
     {
         // get class name
         if (\is_object($eventObj)) {
diff --git a/wcfsetup/install/files/lib/system/event/IEventListener.class.php b/wcfsetup/install/files/lib/system/event/IEventListener.class.php
index f4ea2bc5b27..b776ada0969 100644
--- a/wcfsetup/install/files/lib/system/event/IEventListener.class.php
+++ b/wcfsetup/install/files/lib/system/event/IEventListener.class.php
@@ -19,6 +19,7 @@ interface IEventListener
      * @param mixed $eventObj
      * @param string $className
      * @param string $eventName
+     * @return void
      */
     public function execute($eventObj, $className, $eventName);
 }
diff --git a/wcfsetup/install/files/lib/system/event/listener/AbstractHtmlInputNodeProcessorListener.class.php b/wcfsetup/install/files/lib/system/event/listener/AbstractHtmlInputNodeProcessorListener.class.php
index 28f8362732d..12cbb6a71fc 100644
--- a/wcfsetup/install/files/lib/system/event/listener/AbstractHtmlInputNodeProcessorListener.class.php
+++ b/wcfsetup/install/files/lib/system/event/listener/AbstractHtmlInputNodeProcessorListener.class.php
@@ -26,7 +26,7 @@ abstract class AbstractHtmlInputNodeProcessorListener implements IParameterizedE
      *
      * @param HtmlInputNodeProcessor $processor
      * @param Regex $regex
-     * @return  int[]
+     * @return int[]
      */
     protected function getObjectIDs(HtmlInputNodeProcessor $processor, Regex $regex)
     {
@@ -48,7 +48,7 @@ protected function getObjectIDs(HtmlInputNodeProcessor $processor, Regex $regex)
      *
      * @param string $link
      * @param string $defaultAnchor
-     * @return  Regex
+     * @return Regex
      */
     protected function getRegexFromLink($link, $defaultAnchor = '')
     {
@@ -66,6 +66,7 @@ protected function getRegexFromLink($link, $defaultAnchor = '')
      * @param Regex $regex
      * @param ITitledObject[] $objects
      * @param string $bbcodeName
+     * @return void
      * @deprecated 5.2 Use `replaceLinks()` instead.
      */
     protected function replaceLinksWithBBCode(
@@ -84,7 +85,8 @@ protected function replaceLinksWithBBCode(
      * @param HtmlInputNodeProcessor $processor
      * @param Regex $regex
      * @param ITitledObject[] $objects
-     * @throws  ImplementationException
+     * @return void
+     * @throws ImplementationException
      * @deprecated 5.2 Use `replaceLinks()` instead.
      */
     protected function setObjectTitles(HtmlInputNodeProcessor $processor, Regex $regex, array $objects)
@@ -96,6 +98,7 @@ protected function setObjectTitles(HtmlInputNodeProcessor $processor, Regex $reg
      * @param HtmlInputNodeProcessor $processor
      * @param ITitledObject[] $objects
      * @param string $bbcodeName
+     * @return void
      */
     protected function replaceLinks(HtmlInputNodeProcessor $processor, array $objects, $bbcodeName = '')
     {
diff --git a/wcfsetup/install/files/lib/system/event/listener/AbstractUserActionRenameListener.class.php b/wcfsetup/install/files/lib/system/event/listener/AbstractUserActionRenameListener.class.php
index 1e449cb9777..045f03e1c4d 100644
--- a/wcfsetup/install/files/lib/system/event/listener/AbstractUserActionRenameListener.class.php
+++ b/wcfsetup/install/files/lib/system/event/listener/AbstractUserActionRenameListener.class.php
@@ -24,7 +24,7 @@ abstract class AbstractUserActionRenameListener implements IParameterizedEventLi
      * table columns containing the id and name of the user)
      * `{WCF_N}` will be automatically replaced with the number of the WCF installation
      * (only with PHP 5.6 string concatenation is possible in property declarations)
-     * @var array
+     * @var array<string|array{name: string, userID?: string, username?: string}>
      */
     protected $databaseTables = [];
 
diff --git a/wcfsetup/install/files/lib/system/event/listener/AbstractUserMergeListener.class.php b/wcfsetup/install/files/lib/system/event/listener/AbstractUserMergeListener.class.php
index 88bea102a59..aa226209a8e 100644
--- a/wcfsetup/install/files/lib/system/event/listener/AbstractUserMergeListener.class.php
+++ b/wcfsetup/install/files/lib/system/event/listener/AbstractUserMergeListener.class.php
@@ -28,7 +28,7 @@ abstract class AbstractUserMergeListener implements IParameterizedEventListener
      * GNORE query should be used)
      * `{WCF_N}` will be automatically replaced with the number of the WCF installation
      * (only with PHP 5.6 string concatenation is possible in property declarations)
-     * @var array
+     * @var array<string|array{name: string, userID?: string, username?: string, ignore?: bool}>
      */
     protected $databaseTables = [];
 
diff --git a/wcfsetup/install/files/lib/system/event/listener/IParameterizedEventListener.class.php b/wcfsetup/install/files/lib/system/event/listener/IParameterizedEventListener.class.php
index 156b4d64894..f23c4350fd3 100644
--- a/wcfsetup/install/files/lib/system/event/listener/IParameterizedEventListener.class.php
+++ b/wcfsetup/install/files/lib/system/event/listener/IParameterizedEventListener.class.php
@@ -20,7 +20,8 @@ interface IParameterizedEventListener
      * @param mixed $eventObj Object firing the event
      * @param string $className class name of $eventObj
      * @param string $eventName name of the event fired
-     * @param array       &$parameters given parameters
+     * @param mixed[] &$parameters given parameters
+     * @return void
      */
     public function execute($eventObj, $className, $eventName, array &$parameters);
 }
diff --git a/wcfsetup/install/files/lib/system/exception/AJAXException.class.php b/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
index 21108fb4b0c..6f43e6c48b4 100644
--- a/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
@@ -62,6 +62,7 @@ class AJAXException extends LoggedException
      * @param mixed[] $returnValues
      * @param string $exceptionID
      * @param \Exception|\Throwable $previous
+     * @param array<string, mixed> $extraInformation
      */
     public function __construct(
         $message,
diff --git a/wcfsetup/install/files/lib/system/exception/ErrorException.class.php b/wcfsetup/install/files/lib/system/exception/ErrorException.class.php
index b50bbc406e7..df6fa22108c 100644
--- a/wcfsetup/install/files/lib/system/exception/ErrorException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/ErrorException.class.php
@@ -16,11 +16,17 @@ class ErrorException extends SystemException
 {
     /**
      * @inheritDoc
+     * @var int
      */
     protected $severity;
 
     /**
-     * @inheritDoc
+     * @param string $message
+     * @param int $code
+     * @param int $severity
+     * @param string $filename
+     * @param int $lineno
+     * @param ?\Exception $previous
      */
     public function __construct(
         $message = "",
@@ -37,6 +43,7 @@ public function __construct(
 
     /**
      * @inheritDoc
+     * @return int
      */
     public function getSeverity()
     {
diff --git a/wcfsetup/install/files/lib/system/exception/IPrintableException.class.php b/wcfsetup/install/files/lib/system/exception/IPrintableException.class.php
index a4b7326fdd3..07041da8573 100644
--- a/wcfsetup/install/files/lib/system/exception/IPrintableException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/IPrintableException.class.php
@@ -15,6 +15,8 @@ interface IPrintableException
     /**
      * Prints this exception.
      * This method is called by WCF::handleException().
+     *
+     * @return void
      */
     public function show();
 }
diff --git a/wcfsetup/install/files/lib/system/exception/SystemException.class.php b/wcfsetup/install/files/lib/system/exception/SystemException.class.php
index 0fabde1b26d..0f3030e9597 100644
--- a/wcfsetup/install/files/lib/system/exception/SystemException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/SystemException.class.php
@@ -68,7 +68,7 @@ public function getExtraInformation()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     public function show()
     {
diff --git a/wcfsetup/install/files/lib/system/exception/UserInputException.class.php b/wcfsetup/install/files/lib/system/exception/UserInputException.class.php
index 24de46ebf4d..0223a5ffb62 100644
--- a/wcfsetup/install/files/lib/system/exception/UserInputException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/UserInputException.class.php
@@ -25,7 +25,7 @@ class UserInputException extends UserException
 
     /**
      * variables for AJAX error handling
-     * @var array
+     * @var array<string, mixed>
      */
     protected $variables = [];
 
@@ -34,7 +34,7 @@ class UserInputException extends UserException
      *
      * @param string $field affected formular field
      * @param string|mixed[] $type kind of this error
-     * @param array $variables additional variables for AJAX error handling
+     * @param array<string, mixed> $variables additional variables for AJAX error handling
      */
     public function __construct($field = '', $type = 'empty', array $variables = [])
     {
@@ -49,7 +49,7 @@ public function __construct($field = '', $type = 'empty', array $variables = [])
     /**
      * Returns the affected formular field of this error.
      *
-     * @return  string
+     * @return string
      */
     public function getField()
     {
@@ -59,7 +59,7 @@ public function getField()
     /**
      * Returns the kind of this error.
      *
-     * @return  string|mixed[]
+     * @return string|mixed[]
      */
     public function getType()
     {
@@ -69,7 +69,7 @@ public function getType()
     /**
      * Returns additional variables for AJAX error handling.
      *
-     * @return  array
+     * @return array<string, mixed>
      */
     public function getVariables()
     {
diff --git a/wcfsetup/install/files/lib/system/exception/ValidateActionException.class.php b/wcfsetup/install/files/lib/system/exception/ValidateActionException.class.php
index 1ad2b61b254..1b2c5bd5e73 100644
--- a/wcfsetup/install/files/lib/system/exception/ValidateActionException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/ValidateActionException.class.php
@@ -27,9 +27,9 @@ class ValidateActionException extends \Exception
     protected $fieldName = '';
 
     /**
-     * @inheritDoc
+     * @param array<string, mixed> $variables
      */
-    public function __construct($fieldName, $errorMessage = 'empty', array $variables = [])
+    public function __construct(string $fieldName, string $errorMessage = 'empty', array $variables = [])
     {
         $this->errorMessage = $errorMessage;
         if (!\str_contains($this->errorMessage, '.')) {
diff --git a/wcfsetup/install/files/lib/system/exporter/AbstractExporter.class.php b/wcfsetup/install/files/lib/system/exporter/AbstractExporter.class.php
index 7f17d180a2b..11efc64c65b 100644
--- a/wcfsetup/install/files/lib/system/exporter/AbstractExporter.class.php
+++ b/wcfsetup/install/files/lib/system/exporter/AbstractExporter.class.php
@@ -17,7 +17,7 @@ abstract class AbstractExporter implements IExporter
 {
     /**
      * additional data
-     * @var array
+     * @var array<string, mixed>
      */
     public $additionalData = [];
 
@@ -65,7 +65,7 @@ abstract class AbstractExporter implements IExporter
 
     /**
      * object type => method names
-     * @var array
+     * @var array<string, string>
      */
     protected $methods = [];
 
diff --git a/wcfsetup/install/files/lib/system/exporter/IExporter.class.php b/wcfsetup/install/files/lib/system/exporter/IExporter.class.php
index aa761d8fe45..2c1ebb956e0 100644
--- a/wcfsetup/install/files/lib/system/exporter/IExporter.class.php
+++ b/wcfsetup/install/files/lib/system/exporter/IExporter.class.php
@@ -20,7 +20,8 @@ interface IExporter
      * @param string $databaseName
      * @param string $databasePrefix
      * @param string $fileSystemPath
-     * @param array $additionalData
+     * @param array<string, mixed> $additionalData
+     * @return void
      */
     public function setData(
         $databaseHost,
@@ -34,6 +35,8 @@ public function setData(
 
     /**
      * Initializes this exporter.
+     *
+     * @return void
      */
     public function init();
 
@@ -41,7 +44,7 @@ public function init();
      * Counts the number of required loops for given type.
      *
      * @param string $objectType
-     * @return  int
+     * @return int
      */
     public function countLoops($objectType);
 
@@ -50,35 +53,37 @@ public function countLoops($objectType);
      *
      * @param string $objectType
      * @param int $loopCount
+     * @return void
      */
     public function exportData($objectType, $loopCount = 0);
 
     /**
      * Validates database access.
      *
-     * @throws  \wcf\system\database\exception\DatabaseException
+     * @return void
+     * @throws \wcf\system\database\exception\DatabaseException
      */
     public function validateDatabaseAccess();
 
     /**
      * Validates given file system path. Returns false on failure.
      *
-     * @return  bool
+     * @return bool
      */
     public function validateFileAccess();
 
     /**
      * Validates the selected data types. Returns false on failure.
      *
-     * @param array $selectedData
-     * @return  bool
+     * @param string[] $selectedData
+     * @return bool
      */
     public function validateSelectedData(array $selectedData);
 
     /**
      * Returns the import worker queue.
      *
-     * @return  array
+     * @return string[]
      */
     public function getQueue();
 
@@ -92,7 +97,7 @@ public function getSupportedData();
     /**
      * Returns a default database table prefix.
      *
-     * @return  string
+     * @return string
      */
     public function getDefaultDatabasePrefix();
 }
diff --git a/wcfsetup/install/files/lib/system/file/processor/AttachmentFileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/AttachmentFileProcessor.class.php
index 9ab151e2011..254dab5ecef 100644
--- a/wcfsetup/install/files/lib/system/file/processor/AttachmentFileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/AttachmentFileProcessor.class.php
@@ -37,7 +37,8 @@ public function getAllowedFileExtensions(array $context): array
             return [];
         }
 
-        return $attachmentHandler->getAllowedExtensions();    }
+        return $attachmentHandler->getAllowedExtensions();
+    }
 
     #[\Override]
     public function canAdopt(File $file, array $context): bool
@@ -118,7 +119,7 @@ public function canDownload(File $file): bool
     }
 
     #[\Override]
-    public function getMaximumCount(array $context): ?int
+    public function getMaximumCount(array $context): int
     {
         $attachmentHandler = $this->getAttachmentHandlerFromContext($context);
         if ($attachmentHandler === null) {
@@ -277,6 +278,9 @@ public function getMaximumSize(array $context): ?int
         return $attachmentHandler?->getMaxSize();
     }
 
+    /**
+     * @param array<string, mixed> $context
+     */
     private function getAttachmentHandlerFromContext(array $context): ?AttachmentHandler
     {
         try {
diff --git a/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
index 99be931a194..ca187d841ea 100644
--- a/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
@@ -4,7 +4,6 @@
 
 use wcf\data\file\File;
 use wcf\data\file\FileEditor;
-use wcf\data\file\thumbnail\FileThumbnail;
 use wcf\data\file\thumbnail\FileThumbnailEditor;
 use wcf\data\file\thumbnail\FileThumbnailList;
 use wcf\data\object\type\ObjectType;
@@ -17,7 +16,6 @@
 use wcf\system\file\processor\exception\DamagedImage;
 use wcf\system\image\adapter\exception\ImageNotProcessable;
 use wcf\system\image\adapter\exception\ImageNotReadable;
-use wcf\system\image\adapter\ImageAdapter;
 use wcf\system\image\ImageHandler;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
@@ -32,6 +30,7 @@
  * @copyright 2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
+ * @phpstan-type Context array<string, mixed>
  */
 final class FileProcessor extends SingletonFactory
 {
@@ -73,6 +72,9 @@ public function getObjectType(string $objectType): ?ObjectType
         return $this->objectTypes[$objectType] ?? null;
     }
 
+    /**
+     * @param Context $context
+     */
     public function getHtmlElement(IFileProcessor $fileProcessor, array $context): string
     {
         $allowedFileExtensions = $fileProcessor->getAllowedFileExtensions($context);
@@ -133,6 +135,9 @@ public function getHtmlElement(IFileProcessor $fileProcessor, array $context): s
         );
     }
 
+    /**
+     * @param Context $context
+     */
     public function canAdopt(IFileProcessor $fileProcessor, File $file, array $context): bool
     {
         $objectType = $this->getObjectType($fileProcessor->getObjectTypeName());
@@ -309,6 +314,9 @@ public function generateThumbnails(File $file): void
         }
     }
 
+    /**
+     * @param File[] $files
+     */
     public function delete(array $files): void
     {
         $fileIDs = \array_column($files, 'fileID');
@@ -328,6 +336,9 @@ public function delete(array $files): void
         }
     }
 
+    /**
+     * @param Context $context
+     */
     public function hasReachedUploadLimit(IFileProcessor $fileProcessor, array $context): bool
     {
         $isReplacement = $context['__replace'] ?? false;
diff --git a/wcfsetup/install/files/lib/system/file/processor/IFileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/IFileProcessor.class.php
index 9bf105e0c0e..dab5e98cd8c 100644
--- a/wcfsetup/install/files/lib/system/file/processor/IFileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/IFileProcessor.class.php
@@ -17,6 +17,7 @@
  * @copyright 2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
+ * @phpstan-type Context array<string, mixed>
  */
 interface IFileProcessor
 {
@@ -26,6 +27,8 @@ interface IFileProcessor
      * The `$context` variable is echoed from the `<woltlab-core-file-upload>`
      * element and intended to provide additional context to make decisions. The
      * value is stored for use with the temporary file later.
+     *
+     * @param Context $context
      */
     public function acceptUpload(string $filename, int $fileSize, array $context): FileProcessorPreflightResult;
 
@@ -43,6 +46,8 @@ public function validateUpload(File $file): void;
      * The `$file` can be assigned if one of the following conditions is met:
      * - The file has not yet been assigned to any object
      * - The file is already assigned to the object referenced by `$context`
+     *
+     * @param Context $context
      */
     public function canAdopt(File $file, array $context): bool;
 
@@ -52,6 +57,8 @@ public function canAdopt(File $file, array $context): bool;
      *
      * `$context` are the exact same values that have previously been passed to
      * `canAdopt()` before.
+     *
+     * @param Context $context
      */
     public function adopt(File $file, array $context): void;
 
@@ -82,7 +89,7 @@ public function canDownload(File $file): bool;
      * implementation may opt out of this by returning `null` which means that
      * it does not track this for whatever reason.
      *
-     * @param array<string,string> $context
+     * @param Context $context
      * @return null|int Number of existing files or `null` if this should not be enforced
      */
     public function countExistingFiles(array $context): ?int;
@@ -101,6 +108,7 @@ public function delete(array $fileIDs, array $thumbnailIDs): void;
      *
      * The special value '*' indicates that all file extensions are acceptable.
      *
+     * @param Context $context
      * @return list<string>
      */
     public function getAllowedFileExtensions(array $context): array;
@@ -115,15 +123,16 @@ public function getFileCacheDuration(File $file): FileCacheDuration;
      * Limits the maximum number of files that can be uploaded for the provided
      * context.
      *
-     * @return null|int Maximum number of files or `null` for an indefinite amount.
+     * @param Context $context
+     * @return ?int Maximum number of files or `null` for an indefinite amount.
      */
     public function getMaximumCount(array $context): ?int;
 
     /**
      * Limits the maximum size of an uploade file.
      *
-     * @param array<string,string> $context
-     * @return null|int Maximum size in bytes or null to disable the limit.
+     * @param Context $context
+     * @return ?int Maximum size in bytes or null to disable the limit.
      */
     public function getMaximumSize(array $context): ?int;
 
@@ -148,6 +157,8 @@ public function getThumbnailFormats(): array;
     /**
      * Returns additional meta data for this file that will be transmitted to
      * the client.
+     *
+     * @return array<string, mixed>
      */
     public function getUploadResponse(File $file): array;
 
diff --git a/wcfsetup/install/files/lib/system/file/processor/UserAvatarFileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/UserAvatarFileProcessor.class.php
index 82815a1ce36..a21fc0882f6 100644
--- a/wcfsetup/install/files/lib/system/file/processor/UserAvatarFileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/UserAvatarFileProcessor.class.php
@@ -216,6 +216,9 @@ public function getImageCropperConfiguration(): ImageCropperConfiguration
         );
     }
 
+    /**
+     * @param array<string, mixed> $context
+     */
     private function getUser(array $context): ?UserProfile
     {
         $userID = $context['objectID'] ?? null;
diff --git a/wcfsetup/install/files/lib/system/file/processor/UserCoverPhotoFileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/UserCoverPhotoFileProcessor.class.php
index fa3831a5dcb..88f27e46b4f 100644
--- a/wcfsetup/install/files/lib/system/file/processor/UserCoverPhotoFileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/UserCoverPhotoFileProcessor.class.php
@@ -47,6 +47,9 @@ public function canAdopt(File $file, array $context): bool
         return false;
     }
 
+    /**
+     * @param array<string, mixed> $context
+     */
     private function getUser(array $context): ?UserProfile
     {
         $userID = $context['objectID'] ?? null;
diff --git a/wcfsetup/install/files/lib/system/file/upload/UploadField.class.php b/wcfsetup/install/files/lib/system/file/upload/UploadField.class.php
index d9a6da3e61b..a217831fdbd 100644
--- a/wcfsetup/install/files/lib/system/file/upload/UploadField.class.php
+++ b/wcfsetup/install/files/lib/system/file/upload/UploadField.class.php
@@ -115,6 +115,7 @@ public function getFieldId()
      * Sets the internalId for this field.
      *
      * @param string $internalId
+     * @return void
      */
     public function setInternalId($internalId)
     {
@@ -139,6 +140,7 @@ public function getInternalId()
      * false it will clear the acceptable types if they are `image/*`.
      *
      * @param bool $imageOnly
+     * @return void
      */
     public function setImageOnly($imageOnly)
     {
@@ -165,8 +167,9 @@ public function setImageOnly($imageOnly)
      * use this option, outside the acp or check the file whether remote code is contained.
      *
      * @param bool $allowSvgImage
+     * @return void
      *
-     * @throws      \BadMethodCallException         if the imageOnly flag isn't set to true
+     * @throws \BadMethodCallException         if the imageOnly flag isn't set to true
      */
     public function setAllowSvgImage($allowSvgImage)
     {
@@ -193,9 +196,10 @@ public function setAllowSvgImage($allowSvgImage)
      * - `image/*`
      * - `video/*`
      *
-     * @see         https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers
+     * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers
      * @param string[]|null $acceptableFiles
-     * @since       5.3
+     * @return void
+     * @since 5.3
      */
     public function setAcceptableFiles($acceptableFiles = null)
     {
@@ -205,8 +209,8 @@ public function setAcceptableFiles($acceptableFiles = null)
     /**
      * Returns the acceptable file types.
      *
-     * @return      string[]|null
-     * @since       5.3
+     * @return string[]|null
+     * @since 5.3
      */
     public function getAcceptableFiles()
     {
diff --git a/wcfsetup/install/files/lib/system/file/upload/UploadFile.class.php b/wcfsetup/install/files/lib/system/file/upload/UploadFile.class.php
index b044bae93c6..f31170f7b8b 100644
--- a/wcfsetup/install/files/lib/system/file/upload/UploadFile.class.php
+++ b/wcfsetup/install/files/lib/system/file/upload/UploadFile.class.php
@@ -73,7 +73,7 @@ class UploadFile
 
     /**
      * The return value of `getimagesize`.
-     * @var array|false
+     * @var array{0: int, 1: int, 2: int, 3: string, bits: int, channels: int, mime: string}|false
      */
     private $imageData;
 
@@ -225,6 +225,7 @@ public function getUniqueFileId()
      * sets the `processed` attribute to true.
      *
      * @param string $newLocation
+     * @return void
      */
     public function setProcessed($newLocation)
     {
@@ -240,6 +241,7 @@ public function setProcessed($newLocation)
      * Sets the new image link of the file for processed files.
      *
      * @param string $link
+     * @return void
      */
     public function setImageLink($link)
     {
diff --git a/wcfsetup/install/files/lib/system/file/upload/UploadHandler.class.php b/wcfsetup/install/files/lib/system/file/upload/UploadHandler.class.php
index 79698d38713..3e923858ad4 100644
--- a/wcfsetup/install/files/lib/system/file/upload/UploadHandler.class.php
+++ b/wcfsetup/install/files/lib/system/file/upload/UploadHandler.class.php
@@ -15,6 +15,12 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
+ * @phpstan-type StorageEntry array{
+ *  field: UploadField,
+ *  files: UploadFile[],
+ *  removedFiles: UploadFile[],
+ *  registered: int,
+ * }
  */
 class UploadHandler extends SingletonFactory
 {
@@ -39,7 +45,7 @@ class UploadHandler extends SingletonFactory
     /**
      * Contains the registered upload fields.
      *
-     * @var UploadField[]
+     * @var array<string, UploadField>
      */
     protected $fields = [];
 
@@ -54,7 +60,9 @@ protected function init()
     /**
      * Registers a UploadField.
      *
-     * @throws      \InvalidArgumentException       if a field with the given fieldId is already registered
+     * @param ?mixed[] $requestData
+     * @return void
+     * @throws \InvalidArgumentException if a field with the given fieldId is already registered
      */
     public function registerUploadField(UploadField $field, ?array $requestData = null)
     {
@@ -90,8 +98,9 @@ public function registerUploadField(UploadField $field, ?array $requestData = nu
      * Unregisters an upload field by the given field id.
      *
      * @param string $fieldId
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given fieldId is unknown
+     * @throws \InvalidArgumentException if the given fieldId is unknown
      */
     public function unregisterUploadField($fieldId)
     {
@@ -111,9 +120,9 @@ public function unregisterUploadField($fieldId)
      * Returns the uploaded files for a specific fieldId.
      *
      * @param string $fieldId
-     * @return      UploadFile[]
+     * @return UploadFile[]
      *
-     * @throws      \InvalidArgumentException       if the given fieldId is unknown
+     * @throws \InvalidArgumentException if the given fieldId is unknown
      */
     public function getFilesByFieldId($fieldId)
     {
@@ -129,9 +138,9 @@ public function getFilesByFieldId($fieldId)
      *
      * @param string $fieldId
      * @param bool $processFiles
-     * @return      UploadFile[]
+     * @return UploadFile[]
      *
-     * @throws      \InvalidArgumentException       if the given fieldId is unknown
+     * @throws \InvalidArgumentException if the given fieldId is unknown
      */
     public function getRemovedFilesByFieldId($fieldId, $processFiles = true)
     {
@@ -143,6 +152,9 @@ public function getRemovedFilesByFieldId($fieldId, $processFiles = true)
     }
 
     /**
+     * @param string $fieldId
+     * @param bool $processFiles
+     * @return UploadFile[]
      * @deprecated 6.0 This method exists only because of a spelling error in the method name. Use `getRemovedFiledByFieldId` instead.
      */
     public function getRemovedFiledByFieldId($fieldId, $processFiles = true)
@@ -155,7 +167,7 @@ public function getRemovedFiledByFieldId($fieldId, $processFiles = true)
      *
      * @param string $internalId
      * @param bool $processFiles
-     * @return      UploadFile[]
+     * @return UploadFile[]
      */
     public function getRemovedFilesByInternalId($internalId, $processFiles = true)
     {
@@ -181,6 +193,9 @@ public function getRemovedFilesByInternalId($internalId, $processFiles = true)
     }
 
     /**
+     * @param string $internalId
+     * @param bool $processFiles
+     * @return UploadFile[]
      * @deprecated 6.0 This method exists only because of a spelling error in the method name. Use `getRemovedFilesByInternalId` instead.
      */
     public function getRemovedFiledByInternalId($internalId, $processFiles = true)
@@ -193,8 +208,9 @@ public function getRemovedFiledByInternalId($internalId, $processFiles = true)
      *
      * @param string $internalId
      * @param string $uniqueFileId
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given internalId is unknown
+     * @throws \InvalidArgumentException if the given internalId is unknown
      */
     public function removeFile($internalId, $uniqueFileId)
     {
@@ -216,6 +232,7 @@ public function removeFile($internalId, $uniqueFileId)
      *
      * @param string $internalId
      * @param UploadFile $file
+     * @return void
      */
     private function removeFileByObject($internalId, UploadFile $file)
     {
@@ -242,9 +259,9 @@ private function removeFileByObject($internalId, UploadFile $file)
      * Renders the field with the given fieldId for the template.
      *
      * @param string $fieldId
-     * @return      string
+     * @return string
      *
-     * @throws      \InvalidArgumentException       if the given fieldId is unknown
+     * @throws \InvalidArgumentException if the given fieldId is unknown
      */
     public function renderField($fieldId)
     {
@@ -263,7 +280,7 @@ public function renderField($fieldId)
      * Returns true, if the given internalId is valid.
      *
      * @param string $internalId
-     * @return      bool
+     * @return bool
      */
     public function isValidInternalId($internalId)
     {
@@ -275,7 +292,7 @@ public function isValidInternalId($internalId)
      *
      * @param string $internalId
      * @param string $uniqueFileId
-     * @return      bool
+     * @return bool
      */
     public function isValidUniqueFileId($internalId, $uniqueFileId)
     {
@@ -287,9 +304,9 @@ public function isValidUniqueFileId($internalId, $uniqueFileId)
      *
      * @param string $internalId
      * @param string $uniqueFileId
-     * @return      UploadFile|null
+     * @return ?UploadFile
      *
-     * @throws      \InvalidArgumentException       if the given internalId is unknown
+     * @throws \InvalidArgumentException if the given internalId is unknown
      */
     public function getFileByUniqueFileId($internalId, $uniqueFileId)
     {
@@ -310,7 +327,7 @@ public function getFileByUniqueFileId($internalId, $uniqueFileId)
      * Add a file for an internalId.
      *
      * @param string $internalId
-     * @param UploadFile $file
+     * @return void
      */
     public function addFileByInternalId($internalId, UploadFile $file)
     {
@@ -325,8 +342,9 @@ public function addFileByInternalId($internalId, UploadFile $file)
      *
      * @param string $internalId
      * @param UploadFile[] $files
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given internalId is unknown
+     * @throws \InvalidArgumentException       if the given internalId is unknown
      */
     public function registerFilesByInternalId($internalId, array $files)
     {
@@ -352,6 +370,7 @@ public function registerFilesByInternalId($internalId, array $files)
      *
      * @param string $fieldId
      * @param UploadFile $file
+     * @return void
      */
     public function addFileByField($fieldId, UploadFile $file)
     {
@@ -366,8 +385,9 @@ public function addFileByField($fieldId, UploadFile $file)
      *
      * @param string $fieldId
      * @param UploadFile[] $files
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given fieldId is unknown
+     * @throws \InvalidArgumentException if the given fieldId is unknown
      */
     public function registerFilesByField($fieldId, array $files)
     {
@@ -382,9 +402,9 @@ public function registerFilesByField($fieldId, array $files)
      * Returns the field for the internalId.
      *
      * @param string $internalId
-     * @return      UploadField
+     * @return UploadField
      *
-     * @throws      \InvalidArgumentException       if the given internalId is unknown
+     * @throws \InvalidArgumentException       if the given internalId is unknown
      */
     public function getFieldByInternalId($internalId)
     {
@@ -399,7 +419,7 @@ public function getFieldByInternalId($internalId)
      * Returns the count of uploaded files for an internal id.
      *
      * @param string $internalId
-     * @return      int
+     * @return int
      */
     public function getFilesCountByInternalId($internalId)
     {
@@ -410,7 +430,7 @@ public function getFilesCountByInternalId($internalId)
      * Returns true, iff a field with the given fieldId is already registered.
      *
      * @param string $fieldId
-     * @return      bool
+     * @return bool
      */
     public function isRegisteredFieldId($fieldId)
     {
@@ -420,10 +440,9 @@ public function isRegisteredFieldId($fieldId)
     /**
      * Returns the files for an internal identifier.
      *
-     * @param string $internalId
-     * @return      UploadFile[]
+     * @return UploadFile[]
      */
-    private function getFilesByInternalId($internalId)
+    private function getFilesByInternalId(string $internalId): array
     {
         if (isset($this->getStorage()[$internalId])) {
             $files = $this->getStorage()[$internalId]['files'];
@@ -445,9 +464,9 @@ private function getFilesByInternalId($internalId)
     /**
      * Returns the upload handler storage, located in the session var.
      *
-     * @return array
+     * @return array<string, StorageEntry>
      */
-    private function getStorage()
+    private function getStorage(): array
     {
         if (!\is_array(WCF::getSession()->getVar(self::UPLOAD_HANDLER_SESSION_VAR))) {
             return [];
@@ -465,7 +484,7 @@ private function cleanupStorage(): void
         $storage = $this->getStorage();
 
         foreach ($storage as $internalID => $storageData) {
-            if (!isset($storageData['registered']) || $storageData['registered'] < (\TIME_NOW - self::UPLOAD_FIELD_SESSION_TIMEOUT)) {
+            if ($storageData['registered'] < (\TIME_NOW - self::UPLOAD_FIELD_SESSION_TIMEOUT)) {
                 unset($storage[$internalID]);
                 $hasChanges = true;
             }
@@ -481,7 +500,7 @@ private function cleanupStorage(): void
      *
      * @param UploadField $field
      */
-    private function registerFieldInStorage(UploadField $field)
+    private function registerFieldInStorage(UploadField $field): void
     {
         $storage = $this->getStorage();
         $storage[$field->getInternalId()] = [
@@ -498,10 +517,8 @@ private function registerFieldInStorage(UploadField $field)
 
     /**
      * Remove the removedFiles from the upload process.
-     *
-     * @param UploadField $field
      */
-    private function processRemovedFiles(UploadField $field)
+    private function processRemovedFiles(UploadField $field): void
     {
         $storage = $this->getStorage();
         $storage[$field->getInternalId()]['removedFiles'] = [];
diff --git a/wcfsetup/install/files/lib/system/form/FormDocument.class.php b/wcfsetup/install/files/lib/system/form/FormDocument.class.php
index 267f62d4e87..eb514394594 100644
--- a/wcfsetup/install/files/lib/system/form/FormDocument.class.php
+++ b/wcfsetup/install/files/lib/system/form/FormDocument.class.php
@@ -26,8 +26,6 @@ class FormDocument
     protected $name = '';
 
     /**
-     * Creates a new instance of FormDocument.
-     *
      * @param string $name
      */
     public function __construct($name)
@@ -38,7 +36,7 @@ public function __construct($name)
     /**
      * Returns form document name.
      *
-     * @return  string
+     * @return string
      */
     public function getName()
     {
@@ -49,6 +47,7 @@ public function getName()
      * Appends a FormElementContainer object.
      *
      * @param IFormElementContainer $container
+     * @return void
      */
     public function appendContainer(IFormElementContainer $container)
     {
@@ -59,6 +58,7 @@ public function appendContainer(IFormElementContainer $container)
      * Prepends a FormElementContainer object.
      *
      * @param IFormElementContainer $container
+     * @return void
      */
     public function prependContainer(IFormElementContainer $container)
     {
@@ -68,7 +68,7 @@ public function prependContainer(IFormElementContainer $container)
     /**
      * Returns assigned FormElementContainer objects.
      *
-     * @return  IFormElementContainer[]
+     * @return IFormElementContainer[]
      */
     public function getContainers()
     {
@@ -79,7 +79,7 @@ public function getContainers()
      * Returns the value of container's child element with given name.
      *
      * @param string $key
-     * @return  mixed
+     * @return mixed
      */
     public function getValue($key)
     {
@@ -94,7 +94,7 @@ public function getValue($key)
     /**
      * Returns HTML-representation of current document.
      *
-     * @return  string
+     * @return string
      */
     public function getHTML()
     {
@@ -109,6 +109,8 @@ public function getHTML()
 
     /**
      * Handles request input variables.
+     *
+     * @return void
      */
     public function handleRequest()
     {
@@ -133,6 +135,7 @@ public function handleRequest()
      *
      * @param string $name
      * @param string $error
+     * @return void
      */
     public function setError($name, $error)
     {
diff --git a/wcfsetup/install/files/lib/system/form/IFormElement.class.php b/wcfsetup/install/files/lib/system/form/IFormElement.class.php
index 1317a3cc298..f534683b699 100644
--- a/wcfsetup/install/files/lib/system/form/IFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/IFormElement.class.php
@@ -11,17 +11,12 @@
  */
 interface IFormElement
 {
-    /**
-     * Creates a new object of type FormElement.
-     *
-     * @param IFormElementContainer $parent
-     */
     public function __construct(IFormElementContainer $parent);
 
     /**
      * Returns form element description.
      *
-     * @return  string
+     * @return string
      */
     public function getDescription();
 
@@ -29,13 +24,14 @@ public function getDescription();
      * Sets form element description.
      *
      * @param string $description
+     * @return void
      */
     public function setDescription($description);
 
     /**
      * Returns label.
      *
-     * @return  string
+     * @return string
      */
     public function getLabel();
 
@@ -43,13 +39,14 @@ public function getLabel();
      * Sets label.
      *
      * @param string $label
+     * @return void
      */
     public function setLabel($label);
 
     /**
      * Returns element's parent container element.
      *
-     * @return  IFormElementContainer
+     * @return IFormElementContainer
      */
     public function getParent();
 
@@ -57,7 +54,7 @@ public function getParent();
      * Returns HTML-representation of current form element.
      *
      * @param string $formName
-     * @return  string
+     * @return string
      */
     public function getHTML($formName);
 
@@ -65,13 +62,14 @@ public function getHTML($formName);
      * Sets localized error message.
      *
      * @param string $error
+     * @return void
      */
     public function setError($error);
 
     /**
      * Returns localized error message, empty if no error occurred.
      *
-     * @return  string
+     * @return string
      */
     public function getError();
 }
diff --git a/wcfsetup/install/files/lib/system/form/IFormElementContainer.class.php b/wcfsetup/install/files/lib/system/form/IFormElementContainer.class.php
index 07565c541b3..c7ad214b807 100644
--- a/wcfsetup/install/files/lib/system/form/IFormElementContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/IFormElementContainer.class.php
@@ -14,7 +14,7 @@ interface IFormElementContainer
     /**
      * Returns form element container description.
      *
-     * @return  string
+     * @return string
      */
     public function getDescription();
 
@@ -22,13 +22,14 @@ public function getDescription();
      * Sets form element container description.
      *
      * @param string $description
+     * @return void
      */
     public function setDescription($description);
 
     /**
      * Returns label.
      *
-     * @return  string
+     * @return string
      */
     public function getLabel();
 
@@ -36,6 +37,7 @@ public function getLabel();
      * Sets label.
      *
      * @param string $label
+     * @return void
      */
     public function setLabel($label);
 
@@ -43,14 +45,14 @@ public function setLabel($label);
      * Returns the value of child element with given name.
      *
      * @param string $key
-     * @return  mixed
+     * @return mixed
      */
     public function getValue($key);
 
     /**
      * Returns a list of child elements.
      *
-     * @return  IFormElement[]
+     * @return IFormElement[]
      */
     public function getChildren();
 
@@ -58,6 +60,7 @@ public function getChildren();
      * Appends a new child to stack.
      *
      * @param IFormElement $element
+     * @return void
      */
     public function appendChild(IFormElement $element);
 
@@ -65,13 +68,15 @@ public function appendChild(IFormElement $element);
      * Prepends a new child to stack.
      *
      * @param IFormElement $element
+     * @return void
      */
     public function prependChild(IFormElement $element);
 
     /**
      * Handles a POST or GET request.
      *
-     * @param array $variables
+     * @param mixed[] $variables
+     * @return void
      */
     public function handleRequest(array $variables);
 
@@ -79,7 +84,7 @@ public function handleRequest(array $variables);
      * Returns HTML-representation of current form element container.
      *
      * @param string $formName
-     * @return  string
+     * @return string
      */
     public function getHTML($formName);
 
@@ -88,6 +93,7 @@ public function getHTML($formName);
      *
      * @param string $name
      * @param string $error
+     * @return void
      */
     public function setError($name, $error);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/FormDocument.class.php b/wcfsetup/install/files/lib/system/form/builder/FormDocument.class.php
index 5c463a1e609..c426d12c936 100644
--- a/wcfsetup/install/files/lib/system/form/builder/FormDocument.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/FormDocument.class.php
@@ -122,7 +122,7 @@ class FormDocument implements IFormDocument
 
     /**
      * request data of the form's field
-     * @var null|array
+     * @var ?mixed[]
      */
     protected $requestData;
 
@@ -259,6 +259,8 @@ public function build()
 
     /**
      * Creates the default button for this form document.
+     *
+     * @return void
      */
     protected function createDefaultButton()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/GridViewFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/GridViewFormNode.class.php
index 04f007b6d41..ac3b0f9f998 100644
--- a/wcfsetup/install/files/lib/system/form/builder/GridViewFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/GridViewFormNode.class.php
@@ -11,18 +11,24 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @phpstan-type GridView AbstractGridView<\wcf\data\DatabaseObject, \wcf\data\DatabaseObjectList<\wcf\data\DatabaseObject>>
  */
 class GridViewFormNode implements IFormChildNode
 {
     use TFormChildNode;
     use TFormNode;
 
+    /**
+     * @var GridView
+     */
     protected AbstractGridView $gridView;
 
     /**
      * Returns the grid view object.
      *
-     * @throws  \BadMethodCallException     if the grid view object has not been set yet
+     * @return GridView
+     * @throws \BadMethodCallException if the grid view object has not been set yet
      */
     public function getGridView(): AbstractGridView
     {
@@ -37,6 +43,8 @@ public function getGridView(): AbstractGridView
 
     /**
      * Sets the grid view object that contains the contents of the form node and returns this form node.
+     *
+     * @param GridView $gridView
      */
     public function gridView(AbstractGridView $gridView): static
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/IFormDocument.class.php b/wcfsetup/install/files/lib/system/form/builder/IFormDocument.class.php
index 666929524b3..367647e0b87 100644
--- a/wcfsetup/install/files/lib/system/form/builder/IFormDocument.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/IFormDocument.class.php
@@ -33,9 +33,9 @@ interface IFormDocument extends IFormParentNode
      * Sets the `action` property of the HTML `form` element and returns this document.
      *
      * @param string $action form action
-     * @return  static              this document
+     * @return static this document
      *
-     * @throws  \InvalidArgumentException   if the given action is invalid
+     * @throws \InvalidArgumentException if the given action is invalid
      */
     public function action($action);
 
@@ -44,7 +44,7 @@ public function action($action);
      * document.
      *
      * @param IFormButton $button added button
-     * @return  static              this document
+     * @return static this document
      */
     public function addButton(IFormButton $button);
 
@@ -52,8 +52,8 @@ public function addButton(IFormButton $button);
      * Sets whether the default button is added to the form during in the `build()` method.
      *
      * @param bool $addDefaultButton
-     * @return  static              this document
-     * @throws  \BadMethodCallException     if the form has already been built
+     * @return static this document
+     * @throws \BadMethodCallException if the form has already been built
      */
     public function addDefaultButton($addDefaultButton = true);
 
@@ -62,7 +62,7 @@ public function addDefaultButton($addDefaultButton = true);
      * request and returns his document.
      *
      * @param bool $ajax
-     * @return  static      this document
+     * @return static this document
      */
     public function ajax($ajax = true);
 
@@ -73,16 +73,16 @@ public function ajax($ajax = true);
      * perform actions that require the whole document having finished constructing
      * itself and every parent-child relationship being established.
      *
-     * @return  static              this document
+     * @return static this document
      *
-     * @throws  \BadMethodCallException     if this document has already been built
+     * @throws \BadMethodCallException if this document has already been built
      */
     public function build();
 
     /**
      * Returns `true` if the form data has been read via `readData()` and `false` otherwise.
      *
-     * @return  bool
+     * @return bool
      */
     public function didReadValues();
 
@@ -93,11 +93,11 @@ public function didReadValues();
      * Unsetting the current error message causes `IFormDocument::getErrorMessage()` to
      * return the default error message.
      *
-     * @param null|string $languageItem language item containing the error message or `null` to unset error message
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this document
+     * @param ?string $languageItem language item containing the error message or `null` to unset error message
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this document
      *
-     * @throws  \InvalidArgumentException   if the given form mode is invalid
+     * @throws \InvalidArgumentException if the given form mode is invalid
      */
     public function errorMessage($languageItem = null, array $variables = []);
 
@@ -105,19 +105,19 @@ public function errorMessage($languageItem = null, array $variables = []);
      * Sets the form mode (see `self::FORM_MODE_*` constants).
      *
      * @param string $formMode form mode
-     * @return  static              this document
+     * @return static this document
      *
-     * @throws  \BadMethodCallException     if the form mode has already been set
-     * @throws  \InvalidArgumentException   if the given form mode is invalid
+     * @throws \BadMethodCallException if the form mode has already been set
+     * @throws \InvalidArgumentException if the given form mode is invalid
      */
     public function formMode($formMode);
 
     /**
      * Returns the `action` property of the HTML `form` element.
      *
-     * @return  string              form action
+     * @return string form action
      *
-     * @throws  \BadMethodCallException     if no action has been set and `isAjax()` is `false`
+     * @throws \BadMethodCallException if no action has been set and `isAjax()` is `false`
      */
     public function getAction();
 
@@ -125,16 +125,16 @@ public function getAction();
      * Returns the button with the given id.
      *
      * @param string $buttonId id of requested button
-     * @return  IFormButton
+     * @return IFormButton
      *
-     * @throws  \InvalidArgumentException   if no such button exists
+     * @throws \InvalidArgumentException if no such button exists
      */
     public function getButton($buttonId);
 
     /**
      * Returns the buttons registered for this form document.
      *
-     * @return  IFormButton[]
+     * @return IFormButton[]
      */
     public function getButtons();
 
@@ -142,9 +142,9 @@ public function getButtons();
      * Returns the array passed as the `$parameters` argument of the constructor
      * of a database object action.
      *
-     * @return  array       data passed to database object action
+     * @return array<string, mixed> data passed to database object action
      *
-     * @throws  \BadMethodCallException     if the method is called before `readValues()` is called
+     * @throws \BadMethodCallException if the method is called before `readValues()` is called
      */
     public function getData();
 
@@ -156,7 +156,7 @@ public function getData();
      * Note: The data handler comes with `DefaultFormFieldDataProcessor` as its
      * initial data processor.
      *
-     * @return  IFormDataHandler    form data handler
+     * @return IFormDataHandler form data handler
      */
     public function getDataHandler();
 
@@ -165,7 +165,7 @@ public function getDataHandler();
      * `IFileFormField`, `multipart/form-data` is returned, otherwise `null`
      * is returned.
      *
-     * @return  null|string     form encoding type
+     * @return ?string form encoding type
      */
     public function getEnctype();
 
@@ -177,7 +177,7 @@ public function getEnctype();
      * be displayed, use `IParentFormNode::hasValidationErrors()` and
      * `IFormDocument::showsErrorMessage()`.
      *
-     * @return  string
+     * @return string
      */
     public function getErrorMessage();
 
@@ -188,7 +188,7 @@ public function getErrorMessage();
      * is added or an existing object is edited. If no form mode has been
      * explicitly set, `self::FORM_MODE_CREATE` is set and returned.
      *
-     * @return  string      form mode
+     * @return string form mode
      */
     public function getFormMode();
 
@@ -196,7 +196,7 @@ public function getFormMode();
      * Returns the `method` property of the HTML `form` element. If no method
      * has been set, `post` is returned.
      *
-     * @return  string      form method
+     * @return string form method
      */
     public function getMethod();
 
@@ -206,7 +206,7 @@ public function getMethod();
      *
      * Note: If a prefix `foo` has been set, this method returns `foo_`.
      *
-     * @return  string      global form element prefix
+     * @return string global form element prefix
      */
     public function getPrefix();
 
@@ -215,10 +215,10 @@ public function getPrefix();
      *
      * If no request data is set, `$_POST` will be set as the request data.
      *
-     * @param null|string $index array index of the returned data
-     * @return  array|mixed         request data of the form's fields or specific index data if index is given
+     * @param ?string $index array index of the returned data
+     * @return mixed[]|mixed request data of the form's fields or specific index data if index is given
      *
-     * @throws  \InvalidArgumentException   if invalid index is given
+     * @throws \InvalidArgumentException if invalid index is given
      */
     public function getRequestData($index = null);
 
@@ -228,7 +228,7 @@ public function getRequestData($index = null);
      * By default, `wcf.global.form.add` or `wcf.global.form.edit` in the active user's language
      * is returned depending on the current form mode.
      *
-     * @return  string
+     * @return string
      */
     public function getSuccessMessage();
 
@@ -236,7 +236,7 @@ public function getSuccessMessage();
      * Returns `true` if a button with the given id exists and `false` otherwise.
      *
      * @param string $buttonId id of checked button
-     * @return  bool
+     * @return bool
      */
     public function hasButton($buttonId);
 
@@ -247,7 +247,7 @@ public function hasButton($buttonId);
      * By default, the default button is added.
      * Each implementing class can define itself what it considers its default button.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasDefaultButton();
 
@@ -257,8 +257,8 @@ public function hasDefaultButton();
      *
      * If no request data is set, `$_POST` will be set as the request data.
      *
-     * @param null|string $index array index of the returned data
-     * @return  bool
+     * @param ?string $index array index of the returned data
+     * @return bool
      */
     public function hasRequestData($index = null);
 
@@ -268,7 +268,7 @@ public function hasRequestData($index = null);
      *
      * By default, this method returns `false`.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAjax();
 
@@ -278,7 +278,7 @@ public function isAjax();
      *
      * By default, the form document is not invalid.
      *
-     * @return  bool
+     * @return bool
      */
     public function isInvalid();
 
@@ -286,15 +286,15 @@ public function isInvalid();
      * Sets if the form document is in invalid due to external factors.
      *
      * @param bool $invalid
-     * @return  static              this document
+     * @return static this document
      */
     public function invalid($invalid = true);
 
     /**
      * Returns `true` if the information about required fields has to be shown below the form.
      *
-     * @return  bool
-     * @since   5.3
+     * @return bool
+     * @since 5.3
      */
     public function needsRequiredFieldsInfo();
 
@@ -307,15 +307,15 @@ public function needsRequiredFieldsInfo();
      *
      * @param IStorableObject $object updated object
      * @param bool $loadValues indicates if the object's values are loaded
-     * @return  static                  this document
+     * @return static this document
      */
     public function updatedObject(IStorableObject $object, $loadValues = true);
 
     /**
      * Sets whether required fields are marked in the output and returns this document.
      *
-     * @since       5.4
-     * @return      static      this document
+     * @since 5.4
+     * @return static this document
      */
     public function markRequiredFields(bool $markRequiredFields = true);
 
@@ -324,7 +324,7 @@ public function markRequiredFields(bool $markRequiredFields = true);
      *
      * By default, required fields are marked in the output.
      *
-     * @since       5.4
+     * @since 5.4
      */
     public function marksRequiredFields(): bool;
 
@@ -332,9 +332,9 @@ public function marksRequiredFields(): bool;
      * Sets the `method` property of the HTML `form` element and returns this document.
      *
      * @param string $method form method
-     * @return  static              this document
+     * @return static this document
      *
-     * @throws  \InvalidArgumentException   if the given method is invalid
+     * @throws \InvalidArgumentException if the given method is invalid
      */
     public function method($method);
 
@@ -346,19 +346,19 @@ public function method($method);
      * It is only relevant when printing the form and reading the form values.
      *
      * @param string $prefix global form prefix
-     * @return  static              this document
+     * @return static this document
      *
-     * @throws  \InvalidArgumentException   if the given prefix is invalid
+     * @throws \InvalidArgumentException if the given prefix is invalid
      */
     public function prefix($prefix);
 
     /**
      * Sets the request data of the form's fields.
      *
-     * @param array $requestData request data of the form's fields
-     * @return  static              this document
+     * @param mixed[] $requestData request data of the form's fields
+     * @return static this document
      *
-     * @throws  \BadMethodCallException     if request data has already been set
+     * @throws \BadMethodCallException if request data has already been set
      */
     public function requestData(array $requestData);
 
@@ -366,7 +366,7 @@ public function requestData(array $requestData);
      * Sets if the global form error message should be shown if the form has validation errors.
      *
      * @param bool $showErrorMessage
-     * @return  static                  this document
+     * @return static this document
      */
     public function showErrorMessage($showErrorMessage = true);
 
@@ -374,7 +374,7 @@ public function showErrorMessage($showErrorMessage = true);
      * Sets if the global form success message should be shown.
      *
      * @param bool $showSuccessMessage
-     * @return  static                  this document
+     * @return static this document
      */
     public function showSuccessMessage($showSuccessMessage = true);
 
@@ -384,7 +384,7 @@ public function showSuccessMessage($showSuccessMessage = true);
      *
      * By default, the global form error message is shown.
      *
-     * @return  bool
+     * @return bool
      */
     public function showsErrorMessage();
 
@@ -393,7 +393,7 @@ public function showsErrorMessage();
      *
      * By default, the global form error message is not shown.
      *
-     * @return  bool
+     * @return bool
      */
     public function showsSuccessMessage();
 
@@ -404,9 +404,9 @@ public function showsSuccessMessage();
      * Unsetting the current success message causes `IFormDocument::getSuccessMessage()()` to
      * return the default success message.
      *
-     * @param null|string $languageItem language item containing the success message or `null` to unset error message
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this document
+     * @param ?string $languageItem language item containing the success message or `null` to unset error message
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this document
      *
      * @throws  \InvalidArgumentException   if the given form mode is invalid
      */
diff --git a/wcfsetup/install/files/lib/system/form/builder/IFormElement.class.php b/wcfsetup/install/files/lib/system/form/builder/IFormElement.class.php
index 5e5e30ce1fa..c352c7db0e3 100644
--- a/wcfsetup/install/files/lib/system/form/builder/IFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/IFormElement.class.php
@@ -17,25 +17,25 @@ interface IFormElement extends IFormNode
      * and returns this element. If `null` is passed, the element description
      * is removed.
      *
-     * @param null|string $languageItem language item containing the element description or `null` to unset description
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this element
+     * @param ?string $languageItem language item containing the element description or `null` to unset description
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this element
      *
-     * @throws  \InvalidArgumentException   if the given description is invalid
+     * @throws \InvalidArgumentException if the given description is invalid
      */
     public function description($languageItem = null, array $variables = []);
 
     /**
      * Returns the description of this element or `null` if no description has been set.
      *
-     * @return  null|string element description
+     * @return ?string element description
      */
     public function getDescription();
 
     /**
      * Returns the label of this element or `null` if no label has been set.
      *
-     * @return  null|string element label
+     * @return ?string element label
      */
     public function getLabel();
 
@@ -44,9 +44,9 @@ public function getLabel();
      * returns this element. If `null` is passed, the element label is
      * removed.
      *
-     * @param null|string $languageItem language item containing the element label or `null` to unset label
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this element
+     * @param ?string $languageItem language item containing the element label or `null` to unset label
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this element
      *
      * @throws  \InvalidArgumentException   if the given label is invalid
      */
@@ -55,7 +55,7 @@ public function label($languageItem = null, array $variables = []);
     /**
      * Returns `true` if this element requires a label to be set.
      *
-     * @return  bool
+     * @return bool
      */
     public function requiresLabel();
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/IFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/IFormNode.class.php
index 72ca992d230..bc7a830c9df 100644
--- a/wcfsetup/install/files/lib/system/form/builder/IFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/IFormNode.class.php
@@ -17,9 +17,9 @@ interface IFormNode
     /**
      * Adds the given CSS class to this node and returns this node.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function addClass(string $class): static;
 
@@ -27,9 +27,9 @@ public function addClass(string $class): static;
      * Adds the given CSS classes to this node and returns this node.
      *
      * @param string[] $classes
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if any of the given classes is invalid
+     * @throws \InvalidArgumentException if any of the given classes is invalid
      */
     public function addClasses(array $classes): static;
 
@@ -41,7 +41,7 @@ public function addClasses(array $classes): static;
      * This method is expected to set the dependent node of the given dependency
      * to this element.
      *
-     * @return  $this
+     * @return $this
      */
     public function addDependency(IFormFieldDependency $dependency): static;
 
@@ -50,9 +50,9 @@ public function addDependency(IFormFieldDependency $dependency): static;
      *
      * The value of an existing attribute is overwritten by the new value.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if an invalid name or value is given (some attribute names are invalid as there are specific methods for setting that attribute)
+     * @throws \InvalidArgumentException   if an invalid name or value is given (some attribute names are invalid as there are specific methods for setting that attribute)
      */
     public function attribute(string $name, ?string $value = null): static;
 
@@ -73,7 +73,7 @@ public function attribute(string $name, ?string $value = null): static;
      * form field values while this method manages static availability that is independent
      * of form field values and only depends on external factors.
      *
-     * @return  $this
+     * @return $this
      */
     public function available(bool $available = true): static;
 
@@ -83,7 +83,7 @@ public function available(bool $available = true): static;
      *
      * This method is not meant to empty the value of input fields.
      *
-     * @return  $this
+     * @return $this
      */
     public function cleanup(): static;
 
@@ -95,44 +95,44 @@ public function checkDependencies(): bool;
     /**
      * Returns the value of the additional attribute of this node with the given name.
      *
-     * @throws  \InvalidArgumentException   if the given name is invalid or no such attribute exists
+     * @throws \InvalidArgumentException if the given name is invalid or no such attribute exists
      */
     public function getAttribute(string $name): mixed;
 
     /**
      * Returns additional attributes of this node.
      *
-     * @return  array       additional node attributes
+     * @return array<string, ?string> additional node attributes
      */
     public function getAttributes(): array;
 
     /**
      * Returns all CSS classes of this node.
      *
-     * @return  string[]    CSS classes of node
+     * @return string[] CSS classes of node
      */
     public function getClasses(): array;
 
     /**
      * Returns all of the node's dependencies.
      *
-     * @return  IFormFieldDependency[]      node's dependencies
+     * @return IFormFieldDependency[] node's dependencies
      */
     public function getDependencies();
 
     /**
      * Returns the form document this node belongs to.
      *
-     * @return  IFormDocument           form document node belongs to
+     * @return IFormDocument form document node belongs to
      *
-     * @throws  \BadMethodCallException     if form document is inaccessible for this node
+     * @throws \BadMethodCallException if form document is inaccessible for this node
      */
     public function getDocument();
 
     /**
      * Returns the html representation of this node.
      *
-     * @return  string      html representation of node
+     * @return string html representation of node
      */
     public function getHtml();
 
@@ -140,16 +140,16 @@ public function getHtml();
      * Returns additional template variables used to generate the html representation
      * of this node.
      *
-     * @return  array       additional template variables
+     * @return array<string, mixed> additional template variables
      */
     public function getHtmlVariables();
 
     /**
      * Returns the id of the form node.
      *
-     * @return  string      node id
+     * @return string node id
      *
-     * @throws  \BadMethodCallException     if no id has been set
+     * @throws \BadMethodCallException if no id has been set
      */
     public function getId();
 
@@ -160,9 +160,9 @@ public function getId();
      * The prefixed id is primarily intended to be used when outputting the form's
      * fields and reading their values.
      *
-     * @return  string              prefixed node id
+     * @return string prefixed node id
      *
-     * @throws  \BadMethodCallException     if no id has been set or if form document is inaccessible for this node
+     * @throws \BadMethodCallException if no id has been set or if form document is inaccessible for this node
      */
     public function getPrefixedId();
 
@@ -171,9 +171,9 @@ public function getPrefixedId();
      * `false` otherwise.
      *
      * @param string $name attribute name
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given attribute name is invalid
+     * @throws \InvalidArgumentException if the given attribute name is invalid
      */
     public function hasAttribute($name);
 
@@ -181,9 +181,9 @@ public function hasAttribute($name);
      * Returns `true` if a CSS class with the given name exists and returns `false` otherwise.
      *
      * @param string $class checked CSS class
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function hasClass($class);
 
@@ -192,9 +192,9 @@ public function hasClass($class);
      * returns `false` otherwise.
      *
      * @param string $dependencyId id of the checked dependency
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function hasDependency($dependencyId);
 
@@ -202,10 +202,10 @@ public function hasDependency($dependencyId);
      * Sets the id of the node.
      *
      * @param string $id new id of node
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \BadMethodCallException     if id has already been set
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \BadMethodCallException if id has already been set
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function id($id);
 
@@ -214,9 +214,9 @@ public function id($id);
      *
      * If the node's availability has not been explicitly set, `true` is returned.
      *
-     * @return  bool
+     * @return bool
      *
-     * @see     IFormNode::available()
+     * @see IFormNode::available()
      */
     public function isAvailable();
 
@@ -226,9 +226,9 @@ public function isAvailable();
      * This method enables this node to perform actions that require the whole document having
      * finished constructing itself and every parent-child relationship being established.
      *
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \BadMethodCallException     if this node has already been populated
+     * @throws \BadMethodCallException if this node has already been populated
      */
     public function populate();
 
@@ -239,7 +239,7 @@ public function populate();
      * ignores that fact.
      *
      * @param string $name removed attribute
-     * @return  static              this node
+     * @return static this node
      *
      * @throws  \InvalidArgumentException   if the given attribute is invalid
      */
@@ -252,9 +252,9 @@ public function removeAttribute($name);
      * ignores that fact.
      *
      * @param string $class removed CSS class
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function removeClass($class);
 
@@ -262,9 +262,9 @@ public function removeClass($class);
      * Removes the dependency with the given id and returns this node.
      *
      * @param string $dependencyId id of the removed dependency
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid or no such dependency exists
+     * @throws \InvalidArgumentException if the given id is invalid or no such dependency exists
      */
     public function removeDependency($dependencyId);
 
diff --git a/wcfsetup/install/files/lib/system/form/builder/IFormParentNode.class.php b/wcfsetup/install/files/lib/system/form/builder/IFormParentNode.class.php
index 01f9b18cf2a..a3ed0d8b7df 100644
--- a/wcfsetup/install/files/lib/system/form/builder/IFormParentNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/IFormParentNode.class.php
@@ -9,15 +9,16 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ * @extends \RecursiveIterator<int, IFormChildNode>
  */
 interface IFormParentNode extends \Countable, IFormNode, \RecursiveIterator
 {
     /**
      * Appends the given node to this node and returns this node.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \BadMethodCallException     if method is called with multiple `IFormChildNode` as parameter (if mistakenly used instead of `appendChildren()`)
+     * @throws \BadMethodCallException if method is called with multiple `IFormChildNode` as parameter (if mistakenly used instead of `appendChildren()`)
      */
     public function appendChild(IFormChildNode $child): static;
 
@@ -25,14 +26,14 @@ public function appendChild(IFormChildNode $child): static;
      * Appends the given children to this node and returns this node.
      *
      * @param IFormChildNode[] $children
-     * @return  $this
+     * @return $this
      */
     public function appendChildren(array $children): static;
 
     /**
      * Returns all child nodes of this node.
      *
-     * @return  IFormChildNode[]
+     * @return IFormChildNode[]
      */
     public function children(): array;
 
@@ -47,7 +48,7 @@ public function contains(string $nodeId): bool;
      *
      * Note: A class cannot implement `\Iterator` and `\IteratorAggregate` at the same time.
      *
-     * @return  \RecursiveIteratorIterator  recursive iterator for this node
+     * @return \RecursiveIteratorIterator<$this> recursive iterator for this node
      */
     public function getIterator();
 
@@ -57,7 +58,7 @@ public function getIterator();
      * All descendants, not only the direct child nodes, are checked to find the
      * requested node.
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function getNodeById(string $nodeId): ?IFormNode;
 
@@ -72,9 +73,9 @@ public function hasValidationErrors(): bool;
      *
      * @param $child inserted child node
      * @param $referenceNodeId id of the node after which the given node is inserted
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException           if given node cannot be inserted or reference node id is invalid
+     * @throws \InvalidArgumentException if given node cannot be inserted or reference node id is invalid
      */
     public function insertAfter(IFormChildNode $child, string $referenceNodeId): static;
 
@@ -83,9 +84,9 @@ public function insertAfter(IFormChildNode $child, string $referenceNodeId): sta
      *
      * @param $child inserted child node
      * @param $referenceNodeId id of the node before which the given node is inserted
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException           if given node cannot be inserted or reference node id is invalid
+     * @throws \InvalidArgumentException if given node cannot be inserted or reference node id is invalid
      */
     public function insertBefore(IFormChildNode $child, string $referenceNodeId): static;
 
@@ -93,7 +94,7 @@ public function insertBefore(IFormChildNode $child, string $referenceNodeId): st
      * Reads the value of this node and its children from request data and
      * return this field.
      *
-     * @return  $this
+     * @   $this
      */
     public function readValues(): static;
 
@@ -102,7 +103,7 @@ public function readValues(): static;
      *
      * @param $child validated child node
      *
-     * @throws  \InvalidArgumentException       if given node cannot is an invalid child
+     * @throws \InvalidArgumentException if given node cannot is an invalid child
      */
     public function validateChild(IFormChildNode $child): void;
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/LanguageItemFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/LanguageItemFormNode.class.php
index 8ef0c235fb8..1111a519941 100644
--- a/wcfsetup/install/files/lib/system/form/builder/LanguageItemFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/LanguageItemFormNode.class.php
@@ -19,13 +19,13 @@ class LanguageItemFormNode implements IFormChildNode
 
     /**
      * language item shown in the form node
-     * @var null|string
+     * @var ?string
      */
     protected $languageItem;
 
     /**
      * template variables passed to the language item
-     * @var array
+     * @var array<string ,mixed>
      */
     protected $variables = [];
 
@@ -40,7 +40,7 @@ public function getHtml()
     /**
      * Returns the name of the language item shown in the form node.
      *
-     * @throws      \BadMethodCallException         if language item has not been set yet
+     * @throws \BadMethodCallException if language item has not been set yet
      */
     public function getLanguageItem(): string
     {
@@ -53,6 +53,8 @@ public function getLanguageItem(): string
 
     /**
      * Returns the template variables passed to the language item.
+     *
+     * @return array<string, mixed>
      */
     public function getVariables(): array
     {
@@ -62,7 +64,7 @@ public function getVariables(): array
     /**
      * Sets the language item shown in the form node and returns this form node.
      *
-     * @return      static  this form field
+     * @return static this form field
      */
     public function languageItem(string $languageItem)
     {
@@ -82,7 +84,8 @@ public function validate()
     /**
      * Sets the template variables passed to the language item and returns this form node.
      *
-     * @return      static      this form field
+     * @param array<string, mixed> $variables
+     * @return static this form field
      */
     public function variables(array $variables)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/TFormElement.class.php b/wcfsetup/install/files/lib/system/form/builder/TFormElement.class.php
index 5bf2a9991cf..31b977293a0 100644
--- a/wcfsetup/install/files/lib/system/form/builder/TFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/TFormElement.class.php
@@ -33,11 +33,11 @@ trait TFormElement
      * and returns this element. If `null` is passed, the element description
      * is removed.
      *
-     * @param null|string $languageItem language item containing the element description or `null` to unset description
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this element
+     * @param ?string $languageItem language item containing the element description or `null` to unset description
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this element
      *
-     * @throws  \InvalidArgumentException   if the given description is no string or otherwise is invalid
+     * @throws \InvalidArgumentException if the given description is no string or otherwise is invalid
      */
     public function description($languageItem = null, array $variables = [])
     {
@@ -65,7 +65,7 @@ public function description($languageItem = null, array $variables = [])
     /**
      * Returns the description of this element or `null` if no description has been set.
      *
-     * @return  null|string element description
+     * @return ?string element description
      */
     public function getDescription()
     {
@@ -75,7 +75,7 @@ public function getDescription()
     /**
      * Returns the label of this element or `null` if no label has been set.
      *
-     * @return  null|string element label
+     * @return ?string element label
      */
     public function getLabel()
     {
@@ -87,11 +87,11 @@ public function getLabel()
      * returns this element. If `null` is passed, the element label is
      * removed.
      *
-     * @param null|string $languageItem language item containing the element label or `null` to unset label
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this element
+     * @param ?string $languageItem language item containing the element label or `null` to unset label
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this element
      *
-     * @throws  \InvalidArgumentException   if the given label is no string or otherwise is invalid
+     * @throws \InvalidArgumentException if the given label is no string or otherwise is invalid
      */
     public function label($languageItem = null, array $variables = [])
     {
@@ -119,7 +119,7 @@ public function label($languageItem = null, array $variables = [])
     /**
      * Returns `true` if this element requires a label to be set.
      *
-     * @return  bool
+     * @return bool
      */
     public function requiresLabel()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/TFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/TFormNode.class.php
index 69b5c897097..ff239b9cd30 100644
--- a/wcfsetup/install/files/lib/system/form/builder/TFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/TFormNode.class.php
@@ -19,7 +19,7 @@ trait TFormNode
 {
     /**
      * additional attributes of this node
-     * @var array
+     * @var array<string, ?string>
      */
     protected $attributes = [];
 
@@ -56,9 +56,9 @@ trait TFormNode
     /**
      * Adds the given CSS class to this node and returns this node.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function addClass(string $class): static
     {
@@ -74,9 +74,9 @@ public function addClass(string $class): static
     /**
      * Adds the given CSS classes to this node and returns this node.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if any of the given classes is invalid
+     * @throws \InvalidArgumentException if any of the given classes is invalid
      */
     public function addClasses(array $classes): static
     {
@@ -95,7 +95,7 @@ public function addClasses(array $classes): static
      * This method is expected to set the dependent node of the given dependency
      * to this node.
      *
-     * @return  $this
+     * @return $this
      */
     public function addDependency(IFormFieldDependency $dependency): static
     {
@@ -111,9 +111,9 @@ public function addDependency(IFormFieldDependency $dependency): static
      *
      * The value of an existing attribute is overwritten by the new value.
      *
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException   if an invalid name or value is given (some attribute names are invalid as there are specific methods for setting that attribute)
+     * @throws \InvalidArgumentException if an invalid name or value is given (some attribute names are invalid as there are specific methods for setting that attribute)
      */
     public function attribute(string $name, ?string $value = null): static
     {
@@ -147,7 +147,7 @@ public function attribute(string $name, ?string $value = null): static
      * form field values while this method manages static availability that is independent
      * of form field values and only depends on external factors.
      *
-     * @return  $this
+     * @return $this
      */
     public function available(bool $available = true): static
     {
@@ -196,7 +196,7 @@ public function checkDependencies(): bool
      *
      * This method is not meant to empty the value of input fields.
      *
-     * @return  $this
+     * @return $this
      */
     public function cleanup(): static
     {
@@ -206,7 +206,7 @@ public function cleanup(): static
     /**
      * Returns the value of the additional attribute of this node with the given name.
      *
-     * @throws  \InvalidArgumentException   if the given name is invalid or no such attribute exists
+     * @throws \InvalidArgumentException if the given name is invalid or no such attribute exists
      */
     public function getAttribute(string $name): mixed
     {
@@ -220,7 +220,7 @@ public function getAttribute(string $name): mixed
     /**
      * Returns additional attributes of this node.
      *
-     * @return  array       additional node attributes
+     * @return array<string, ?string> additional node attributes
      */
     public function getAttributes(): array
     {
@@ -230,7 +230,7 @@ public function getAttributes(): array
     /**
      * Returns all CSS classes of this node.
      *
-     * @return  string[]
+     * @return string[]
      */
     public function getClasses(): array
     {
@@ -240,7 +240,7 @@ public function getClasses(): array
     /**
      * Returns all of the node's dependencies.
      *
-     * @return  IFormFieldDependency[]      node's dependencies
+     * @return IFormFieldDependency[] node's dependencies
      */
     public function getDependencies()
     {
@@ -250,9 +250,9 @@ public function getDependencies()
     /**
      * Returns the form document this node belongs to.
      *
-     * @return  IFormDocument           form document node belongs to
+     * @return IFormDocument form document node belongs to
      *
-     * @throws  \BadMethodCallException     if form document is inaccessible for this node
+     * @throws \BadMethodCallException if form document is inaccessible for this node
      */
     abstract public function getDocument();
 
@@ -260,7 +260,7 @@ abstract public function getDocument();
      * Returns additional template variables used to generate the html representation
      * of this node.
      *
-     * @return  array       additional template variables
+     * @return array<string, mixed> additional template variables
      */
     public function getHtmlVariables()
     {
@@ -270,9 +270,9 @@ public function getHtmlVariables()
     /**
      * Returns the id of the form node.
      *
-     * @return  string      node id
+     * @return string node id
      *
-     * @throws  \BadMethodCallException     if no id has been set
+     * @throws \BadMethodCallException if no id has been set
      */
     public function getId()
     {
@@ -290,9 +290,9 @@ public function getId()
      * The prefixed id is primarily intended to be used when outputting the form's
      * fields and reading their values.
      *
-     * @return  string              prefixed node id
+     * @return string prefixed node id
      *
-     * @throws  \BadMethodCallException     if no id has been set or if form document is inaccessible for this node
+     * @throws \BadMethodCallException if no id has been set or if form document is inaccessible for this node
      */
     public function getPrefixedId()
     {
@@ -304,9 +304,9 @@ public function getPrefixedId()
      * `false` otherwise.
      *
      * @param string $name attribute name
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given attribute name is invalid
+     * @throws \InvalidArgumentException if the given attribute name is invalid
      */
     public function hasAttribute($name)
     {
@@ -319,9 +319,9 @@ public function hasAttribute($name)
      * Returns `true` if a CSS class with the given name exists and returns `false` otherwise.
      *
      * @param string $class checked CSS class
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function hasClass($class)
     {
@@ -335,9 +335,9 @@ public function hasClass($class)
      * returns `false` otherwise.
      *
      * @param string $dependencyId id of the checked dependency
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function hasDependency($dependencyId)
     {
@@ -354,10 +354,10 @@ public function hasDependency($dependencyId)
      * Sets the id of the node.
      *
      * @param string $id new id of node
-     * @return  static          this node
+     * @return static this node
      *
-     * @throws  \BadMethodCallException     if id has already been set
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \BadMethodCallException if id has already been set
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function id($id)
     {
@@ -377,9 +377,9 @@ public function id($id)
      *
      * If the node's own availability has not been explicitly set, it is assumed to be `true`.
      *
-     * @return  bool
+     * @return bool
      *
-     * @see     IFormNode::available()
+     * @see IFormNode::available()
      */
     public function isAvailable()
     {
@@ -403,9 +403,9 @@ public function isAvailable()
      * This method enables this node to perform actions that require the whole document having
      * finished constructing itself and every parent-child relationship being established.
      *
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \BadMethodCallException     if this node has already been populated
+     * @throws \BadMethodCallException if this node has already been populated
      */
     public function populate()
     {
@@ -446,9 +446,9 @@ public function populate()
      * ignores that fact.
      *
      * @param string $name removed attribute
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \InvalidArgumentException   if the given attribute is invalid
+     * @throws \InvalidArgumentException if the given attribute is invalid
      */
     public function removeAttribute($name)
     {
@@ -466,9 +466,9 @@ public function removeAttribute($name)
      * ignores that fact.
      *
      * @param string $class removed CSS class
-     * @return  static              this node
+     * @return static this node
      *
-     * @throws  \InvalidArgumentException   if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function removeClass($class)
     {
@@ -486,9 +486,9 @@ public function removeClass($class)
      * Removes the dependency with the given id and returns this node.
      *
      * @param string $dependencyId id of the removed dependency
-     * @return  static              this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid or no such dependency exists
+     * @throws \InvalidArgumentException if the given id is invalid or no such dependency exists
      */
     public function removeDependency($dependencyId)
     {
@@ -509,9 +509,9 @@ public function removeDependency($dependencyId)
      * Creates a new element with the given id.
      *
      * @param string $id node id
-     * @return  static      this node
+     * @return static this node
      *
-     * @throws  \InvalidArgumentException   if the given id is already used by another node, or otherwise is invalid
+     * @throws \InvalidArgumentException if the given id is already used by another node, or otherwise is invalid
      */
     public static function create($id)
     {
@@ -521,8 +521,8 @@ public static function create($id)
     /**
      * Returns a list of attributes that are not accessible via the attribute methods.
      *
-     * @return      string[]
-     * @since       5.2.11
+     * @return string[]
+     * @since 5.2.11
      */
     protected static function getReservedAttributes()
     {
@@ -538,8 +538,9 @@ protected static function getReservedAttributes()
      * Checks if the given attribute name class a and a valid attribute name.
      *
      * @param string $name checked argument name
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if the given attribute name is invalid
+     * @throws \InvalidArgumentException if the given attribute name is invalid
      */
     public static function validateAttribute($name)
     {
@@ -556,8 +557,9 @@ public static function validateAttribute($name)
      * Checks if the given parameter class a and a valid node class.
      *
      * @param string $class checked id
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public static function validateClass($class)
     {
@@ -572,8 +574,9 @@ public static function validateClass($class)
      * Checks if the given parameter is a and a valid node id.
      *
      * @param string $id checked id
+     * @return void
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public static function validateId($id)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/TFormParentNode.class.php b/wcfsetup/install/files/lib/system/form/builder/TFormParentNode.class.php
index 41d49a2599f..cc715b7f38f 100644
--- a/wcfsetup/install/files/lib/system/form/builder/TFormParentNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/TFormParentNode.class.php
@@ -32,7 +32,7 @@ trait TFormParentNode
     /**
      * Appends the given node to this node and returns this node.
      *
-     * @throws  \BadMethodCallException     if method is called with more than one parameter (might be mistakenly used instead of `appendChildren()`)
+     * @throws \BadMethodCallException if method is called with more than one parameter (might be mistakenly used instead of `appendChildren()`)
      */
     public function appendChild(IFormChildNode $child): static
     {
@@ -85,7 +85,7 @@ public function contains(string $nodeId): bool
     /**
      * Returns all child nodes of this node.
      *
-     * @return  IFormChildNode[]
+     * @return IFormChildNode[]
      */
     public function children(): array
     {
@@ -98,7 +98,7 @@ public function children(): array
      *
      * This method is not meant to empty the value of input fields.
      *
-     * @return  $this
+     * @return $this
      */
     public function cleanup(): static
     {
@@ -146,7 +146,7 @@ public function getChildren(): ?IFormParentNode
     /**
      * Returns a recursive iterator for this node.
      *
-     * @return  \RecursiveIteratorIterator  recursive iterator for this node
+     * @return \RecursiveIteratorIterator<$this> recursive iterator for this node
      */
     public function getIterator()
     {
@@ -163,7 +163,7 @@ public function getIterator()
      * All descendants, not only the direct child nodes, are checked to find the
      * requested node.
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function getNodeById(string $nodeId): ?IFormNode
     {
@@ -220,7 +220,7 @@ public function hasValidationErrors(): bool
      * @param $referenceNodeId id of the node after which the given node is inserted
      * @return  $this
      *
-     * @throws  \InvalidArgumentException           if given node cannot be inserted or reference node id is invalid
+     * @throws \InvalidArgumentException if given node cannot be inserted or reference node id is invalid
      */
     public function insertAfter(IFormChildNode $child, string $referenceNodeId): static
     {
@@ -249,9 +249,9 @@ public function insertAfter(IFormChildNode $child, string $referenceNodeId): sta
      * Inserts the given node before the node with the given id and returns this node.
      *
      * @param $referenceNodeId id of the node before which the given node is inserted
-     * @return  $this
+     * @return $this
      *
-     * @throws  \InvalidArgumentException           if given node cannot be inserted or reference node id is invalid
+     * @throws \InvalidArgumentException if given node cannot be inserted or reference node id is invalid
      */
     public function insertBefore(IFormChildNode $child, string $referenceNodeId): static
     {
@@ -296,7 +296,7 @@ public function next(): void
      * Reads the value of this node and its children from request data and
      * return this field.
      *
-     * @return  $this
+     * @return $this
      */
     public function readValues(): static
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/TemplateFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/TemplateFormNode.class.php
index 4cbec252aad..1e3e75b0368 100644
--- a/wcfsetup/install/files/lib/system/form/builder/TemplateFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/TemplateFormNode.class.php
@@ -32,7 +32,7 @@ class TemplateFormNode implements IFormChildNode
 
     /**
      * template variables passed to the template
-     * @var array
+     * @var array<string, mixed>
      */
     protected $variables = [];
 
@@ -41,9 +41,9 @@ class TemplateFormNode implements IFormChildNode
      * form node.
      *
      * @param string $application application abbreviation
-     * @return  static              this form node
+     * @return static this form node
      *
-     * @throws  \InvalidArgumentException   if no application with the given abbreviation exists
+     * @throws \InvalidArgumentException if no application with the given abbreviation exists
      */
     public function application($application)
     {
@@ -63,7 +63,7 @@ public function application($application)
      *
      * If no application has been set, `wcf` will be set and return.
      *
-     * @return  string      application abbreviation
+     * @return string application abbreviation
      */
     public function getApplication()
     {
@@ -89,9 +89,9 @@ public function getHtml()
     /**
      * Returns the name of the template with the contents of the form node.
      *
-     * @return  string              name of template with form node contents
+     * @return string name of template with form node contents
      *
-     * @throws  \BadMethodCallException     if template name has not been set yet
+     * @throws \BadMethodCallException if template name has not been set yet
      */
     public function getTemplateName()
     {
@@ -107,7 +107,7 @@ public function getTemplateName()
     /**
      * Returns the template variables passed to the template.
      *
-     * @return  array           template variables passed to template
+     * @return array<string, mixed> template variables passed to template
      */
     public function getVariables()
     {
@@ -118,7 +118,7 @@ public function getVariables()
      * Sets the name of the template with the contents of the form node and returns this form node.
      *
      * @param string $templateName name of template with form node contents
-     * @return  static              this form node
+     * @return static this form node
      */
     public function templateName($templateName)
     {
@@ -138,8 +138,8 @@ public function validate()
     /**
      * Sets the template variables passed to the template and returns this form node.
      *
-     * @param array $variables template variables passed to template
-     * @return  static          this form node
+     * @param array<string, mixed> $variables template variables passed to template
+     * @return static this form node
      */
     public function variables(array $variables)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/button/FormButton.class.php b/wcfsetup/install/files/lib/system/form/builder/button/FormButton.class.php
index d0093415eb7..a415f72a69f 100644
--- a/wcfsetup/install/files/lib/system/form/builder/button/FormButton.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/button/FormButton.class.php
@@ -21,7 +21,7 @@ class FormButton implements IFormButton
 
     /**
      * access key for this form button or `null` if no access key has been set
-     * @var null|string
+     * @var ?string
      */
     protected $accessKey;
 
@@ -32,7 +32,7 @@ class FormButton implements IFormButton
     protected $submit = false;
 
     /**
-     * @inheritDoc
+     * @var string
      */
     protected $templateName = 'shared_formButton';
 
diff --git a/wcfsetup/install/files/lib/system/form/builder/button/IFormButton.class.php b/wcfsetup/install/files/lib/system/form/builder/button/IFormButton.class.php
index 3c545031901..eebfce480e7 100644
--- a/wcfsetup/install/files/lib/system/form/builder/button/IFormButton.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/button/IFormButton.class.php
@@ -19,9 +19,9 @@ interface IFormButton extends IFormChildNode, IFormElement
      * Sets the access key for this form button and returns this form button. If `null` is passed,
      * the previously set access key is unset.
      *
-     * @param null|string $accessKey button access key
-     * @return  static              this form button
-     * @throws  \InvalidArgumentException   if the given access key is invalid
+     * @param ?string $accessKey button access key
+     * @return static this form button
+     * @throws \InvalidArgumentException if the given access key is invalid
      */
     public function accessKey($accessKey = null);
 
@@ -30,7 +30,7 @@ public function accessKey($accessKey = null);
      *
      * By default, no access key is set.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getAccessKey();
 
@@ -38,7 +38,7 @@ public function getAccessKey();
      * Returns `true` this button is an `input[type=submit]` element and `false` if it is a `button`
      * element.
      *
-     * @return  bool
+     * @return bool
      */
     public function isSubmit();
 
@@ -46,7 +46,7 @@ public function isSubmit();
      * Sets whether this button is an `input[type=submit]` element or a `button` element.
      *
      * @param bool $submit
-     * @return  static              this form button
+     * @return static this form button
      */
     public function submit($submit = true);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/container/IFormContainer.class.php b/wcfsetup/install/files/lib/system/form/builder/container/IFormContainer.class.php
index ac733149d6d..205d01d22ad 100644
--- a/wcfsetup/install/files/lib/system/form/builder/container/IFormContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/container/IFormContainer.class.php
@@ -20,8 +20,8 @@ interface IFormContainer extends IFormChildNode, IFormElement, IFormParentNode
     /**
      * Returns `true` if the whole container should be marked as required in the form output.
      *
-     * @return  bool
-     * @since   5.3
+     * @return bool
+     * @since 5.3
      */
     public function markAsRequired();
 
@@ -32,11 +32,11 @@ public function markAsRequired();
      * This method is *not* intended to generally call `IFormField::updatedObject()` on its form field
      * children as these methods are already called by `IFormDocument::updatedObject()`.
      *
-     * @param array $data data from which the values are extracted
+     * @param mixed[] $data data from which the values are extracted
      * @param IStorableObject $object object the data belongs to
      * @param bool $loadValues
      *
-     * @return  static                  this container
+     * @return static this container
      */
     public function updatedObject(array $data, IStorableObject $object, $loadValues = true);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/container/SuffixFormFieldContainer.class.php b/wcfsetup/install/files/lib/system/form/builder/container/SuffixFormFieldContainer.class.php
index 8ba483d18cc..e5107ea7cbe 100644
--- a/wcfsetup/install/files/lib/system/form/builder/container/SuffixFormFieldContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/container/SuffixFormFieldContainer.class.php
@@ -77,8 +77,8 @@ public function getHtml()
     /**
      * Returns the initial option of the suffix selection dropdown.
      *
-     * @return  array
-     * @throws  \BadMethodCallException     if no suffix field is set or has no options
+     * @return array{label: string, value: mixed, depth: int, isSelectable: bool}
+     * @throws \BadMethodCallException if no suffix field is set or has no options
      */
     public function getSelectedSuffixOption()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/container/wysiwyg/WysiwygFormContainer.class.php b/wcfsetup/install/files/lib/system/form/builder/container/wysiwyg/WysiwygFormContainer.class.php
index c40b712363d..d0aa0ed1909 100644
--- a/wcfsetup/install/files/lib/system/form/builder/container/wysiwyg/WysiwygFormContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/container/wysiwyg/WysiwygFormContainer.class.php
@@ -45,7 +45,11 @@ class WysiwygFormContainer extends FormContainer
     /**
      * attachment-related data used to create an `AttachmentHandler` object for the attachment
      * form field
-     * @var null|array
+     * @var ?array{
+     *  objectType: string,
+     *  parentObjectID: int,
+     *  objectID: int,
+     * }
      */
     protected $attachmentData;
 
@@ -599,6 +603,8 @@ public function required($required = true)
 
     /**
      * Sets the attachment handler of the attachment form field.
+     *
+     * @return void
      */
     protected function setAttachmentHandler()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/data/FormDataHandler.class.php b/wcfsetup/install/files/lib/system/form/builder/data/FormDataHandler.class.php
index e4fd15a8f87..339743958cc 100644
--- a/wcfsetup/install/files/lib/system/form/builder/data/FormDataHandler.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/data/FormDataHandler.class.php
@@ -43,6 +43,7 @@ public function getFormData(IFormDocument $document)
         foreach ($this->processors as $processor) {
             $parameters = $processor->processFormData($document, $parameters);
 
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_array($parameters)) {
                 if ($processor instanceof CustomFormDataProcessor) {
                     throw new \UnexpectedValueException("Custom data processor '{$processor->getId()}' does not return an array when processing form data.");
@@ -64,6 +65,7 @@ public function getObjectData(IFormDocument $document, IStorableObject $object)
         foreach ($this->processors as $processor) {
             $data = $processor->processObjectData($document, $data, $object);
 
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_array($data)) {
                 if ($processor instanceof CustomFormDataProcessor) {
                     throw new \UnexpectedValueException("Custom data processor '{$processor->getId()}' does not return an array when processing object data.");
diff --git a/wcfsetup/install/files/lib/system/form/builder/data/IFormDataHandler.class.php b/wcfsetup/install/files/lib/system/form/builder/data/IFormDataHandler.class.php
index ac82fe82cfd..f974eef45c7 100644
--- a/wcfsetup/install/files/lib/system/form/builder/data/IFormDataHandler.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/data/IFormDataHandler.class.php
@@ -23,7 +23,7 @@ interface IFormDataHandler
      *
      * @param IFormDataProcessor $processor added field data processor
      *
-     * @return  static                      this data handler
+     * @return static this data handler
      */
     public function addProcessor(IFormDataProcessor $processor);
 
@@ -32,7 +32,7 @@ public function addProcessor(IFormDataProcessor $processor);
      * array to a database object action.
      *
      * @param IFormDocument $document processed form document
-     * @return  array               data passed to database object action
+     * @return mixed[] data passed to database object action
      */
     public function getFormData(IFormDocument $document);
 
@@ -42,7 +42,7 @@ public function getFormData(IFormDocument $document);
      *
      * @param IFormDocument $document form document whose form field values will be set
      * @param IStorableObject $object object from which the data is extracted
-     * @return  array               processed object data
+     * @return mixed[] processed object data
      */
     public function getObjectData(IFormDocument $document, IStorableObject $object);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/data/processor/CustomFormDataProcessor.class.php b/wcfsetup/install/files/lib/system/form/builder/data/processor/CustomFormDataProcessor.class.php
index 9e91539452f..d34dde45409 100644
--- a/wcfsetup/install/files/lib/system/form/builder/data/processor/CustomFormDataProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/data/processor/CustomFormDataProcessor.class.php
@@ -36,8 +36,8 @@ final class CustomFormDataProcessor extends AbstractFormDataProcessor
      * Initializes a new CustomFormFieldDataProcessor object.
      *
      * @param $id processor id primarily used for error messages, does not have to be unique
-     * @param callable(IFormDocument,array):array $formDataProcessor form data processor callable
-     * @param callable(IFormDocument,array,IStorableObject):array $objectDataProcessor object data processor callable
+     * @param callable(IFormDocument,mixed[]):mixed[] $formDataProcessor form data processor callable
+     * @param callable(IFormDocument,mixed[],IStorableObject):mixed[] $objectDataProcessor object data processor callable
      *
      * @throws  \InvalidArgumentException       if either id or processor callable are invalid
      */
diff --git a/wcfsetup/install/files/lib/system/form/builder/data/processor/DefaultFormDataProcessor.class.php b/wcfsetup/install/files/lib/system/form/builder/data/processor/DefaultFormDataProcessor.class.php
index 42a17d22e5b..130a96d8ae9 100644
--- a/wcfsetup/install/files/lib/system/form/builder/data/processor/DefaultFormDataProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/data/processor/DefaultFormDataProcessor.class.php
@@ -35,7 +35,8 @@ public function processFormData(IFormDocument $document, array $parameters)
      * Fetches all data from the given node and stores it in the given array.
      *
      * @param IFormNode $node node whose data will be fetched
-     * @param array $data data storage
+     * @param mixed[] $data data storage
+     * @return void
      */
     protected function getData(IFormNode $node, array &$data)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/data/processor/IFormDataProcessor.class.php b/wcfsetup/install/files/lib/system/form/builder/data/processor/IFormDataProcessor.class.php
index c9a4d434010..2433fcfda1c 100644
--- a/wcfsetup/install/files/lib/system/form/builder/data/processor/IFormDataProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/data/processor/IFormDataProcessor.class.php
@@ -22,8 +22,8 @@ interface IFormDataProcessor
      * passed to the constructor of a database object action.
      *
      * @param IFormDocument $document documents whose field data is processed
-     * @param array $parameters parameters before processing
-     * @return  array               parameters after processing
+     * @param array{data: array<string, mixed>} $parameters parameters before processing
+     * @return array{data: array<string, mixed>} parameters after processing
      */
     public function processFormData(IFormDocument $document, array $parameters);
 
@@ -32,9 +32,9 @@ public function processFormData(IFormDocument $document, array $parameters);
      * to set the form field values.
      *
      * @param IFormDocument $document documents whose field values will be set using the processed data
-     * @param array $data data before processing
+     * @param array{data: array<string, mixed>} $data data before processing
      * @param IStorableObject $object object the data belongs to
-     * @return  array               data after processing
+     * @return array{data: array<string, mixed>} data after processing
      */
     public function processObjectData(IFormDocument $document, array $data, IStorableObject $object);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/AbstractFormFieldDecorator.class.php b/wcfsetup/install/files/lib/system/form/builder/field/AbstractFormFieldDecorator.class.php
index e373053a117..3c2b1811e7a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/AbstractFormFieldDecorator.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/AbstractFormFieldDecorator.class.php
@@ -210,7 +210,7 @@ public function parent(IFormParentNode $parentNode)
     /**
      * @inheritDoc
      */
-    public function addClass($class): static
+    public function addClass(string $class): static
     {
         $this->field->addClass($class);
 
@@ -240,7 +240,7 @@ public function addDependency(IFormFieldDependency $dependency): static
     /**
      * @inheritDoc
      */
-    public function attribute($name, $value = null): static
+    public function attribute(string $name, ?string $value = null): static
     {
         $this->field->attribute($name, $value);
 
@@ -250,7 +250,7 @@ public function attribute($name, $value = null): static
     /**
      * @inheritDoc
      */
-    public function available($available = true): static
+    public function available(bool $available = true): static
     {
         $this->field->available($available);
 
@@ -278,7 +278,7 @@ public function checkDependencies(): bool
     /**
      * @inheritDoc
      */
-    public function getAttribute($name): mixed
+    public function getAttribute(string $name): mixed
     {
         return $this->field->getAttribute($name);
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/AbstractNumericFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/AbstractNumericFormField.class.php
index c814dcf452d..d05bcff6544 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/AbstractNumericFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/AbstractNumericFormField.class.php
@@ -119,7 +119,7 @@ public function getStep()
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
@@ -239,6 +239,7 @@ public function value($value)
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected static function getReservedFieldAttributes(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ButtonFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ButtonFormField.class.php
index 0b176fa9bea..1589e7a9f8d 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ButtonFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ButtonFormField.class.php
@@ -38,7 +38,8 @@ class ButtonFormField extends AbstractFormField implements IAttributeFormField,
     /**
      * Sets the text shown on the button and returns this form field.
      *
-     * @return  ButtonFormField     this form field
+     * @param array<string, mixed> $variables
+     * @return ButtonFormField this form field
      */
     public function buttonLabel(string $languageItem, array $variables = [])
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/CaptchaFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/CaptchaFormField.class.php
index 36731991747..a2908d8e993 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/CaptchaFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/CaptchaFormField.class.php
@@ -186,7 +186,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'captcha';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ClassNameFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ClassNameFormField.class.php
index 38cd7a21bfc..a47d88c6893 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ClassNameFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ClassNameFormField.class.php
@@ -254,7 +254,7 @@ protected function validateText($text, ?Language $language = null)
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'className';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/DateFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/DateFormField.class.php
index a84a35fd9c0..28b48faa124 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/DateFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/DateFormField.class.php
@@ -444,7 +444,8 @@ public function value($value)
 
     /**
      * @inheritDoc
-     * @since       5.4
+     * @return string[]
+     * @since 5.4
      */
     protected static function getReservedFieldAttributes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/DateRangeFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/DateRangeFormField.class.php
index accb3f29ef1..ce43731602f 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/DateRangeFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/DateRangeFormField.class.php
@@ -74,6 +74,8 @@ public function readValue()
 
     /**
      * Sets if not only the date, but also the time can be set.
+     *
+     * @param bool $supportsTime
      */
     public function supportTime($supportsTime = true): static
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/DescriptionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/DescriptionFormField.class.php
index 4abb0ca40ab..749f456f962 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/DescriptionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/DescriptionFormField.class.php
@@ -24,6 +24,7 @@ public function __construct()
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getDefaultId()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/EmailFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/EmailFormField.class.php
index 5169b48bf56..1f6c7250d35 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/EmailFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/EmailFormField.class.php
@@ -64,7 +64,8 @@ public function __construct()
 
     /**
      * @inheritDoc
-     * @since       5.4
+     * @return string[]
+     * @since 5.4
      */
     protected function getValidAutoCompleteTokens(): array
     {
@@ -74,7 +75,7 @@ protected function getValidAutoCompleteTokens(): array
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
@@ -114,7 +115,8 @@ public function validate()
      * Validates the given email address in the given language.
      *
      * @param ?string $email validated email address
-     * @param null|Language $language language of validated email address or `null` for monolingual email address
+     * @param ?Language $language language of validated email address or `null` for monolingual email address
+     * @return void
      */
     protected function validateEmail($email, ?Language $language = null)
     {
@@ -133,7 +135,8 @@ protected function validateEmail($email, ?Language $language = null)
 
     /**
      * @inheritDoc
-     * @since       5.4
+     * @return string[]
+     * @since 5.4
      */
     protected static function getReservedFieldAttributes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/FileProcessorFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/FileProcessorFormField.class.php
index a0e1ce520d3..f0db7ecf173 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/FileProcessorFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/FileProcessorFormField.class.php
@@ -37,6 +37,9 @@ final class FileProcessorFormField extends AbstractFormField
      */
     protected $javaScriptDataHandlerModule = 'WoltLabSuite/Core/Form/Builder/Field/FileProcessor';
 
+    /**
+     * @var array<string, mixed>
+     */
     private array $context = [];
 
     /**
@@ -48,6 +51,16 @@ final class FileProcessorFormField extends AbstractFormField
     private bool $simpleReplace = false;
     private bool $hideDeleteButton = false;
     private ?string $thumbnailSize = null;
+
+    /**
+     * @var list<array{
+     *  actionName: string,
+     *  title: string,
+     *  icon: ?IFontAwesomeIcon,
+     *  application: string,
+     *  template: string,
+     * }>
+     */
     private array $actionButtons = [];
 
     #[\Override]
@@ -151,12 +164,18 @@ public function singleFileUpload(bool $singleFileUpload = true): self
         return $this;
     }
 
+    /**
+     * @return string
+     */
     #[\Override]
     public function getObjectTypeDefinition()
     {
         return 'com.woltlab.wcf.file';
     }
 
+    /**
+     * @return File[]
+     */
     public function getFiles(): array
     {
         return $this->files;
@@ -261,6 +280,8 @@ public function addActionButton(
 
     /**
      * Returns the context for the file processor.
+     *
+     * @return array<string, mixed>
      */
     public function getContext(): array
     {
@@ -269,6 +290,8 @@ public function getContext(): array
 
     /**
      * Sets the context for the file processor.
+     *
+     * @param array<string, mixed> $context
      */
     public function context(array $context): self
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/FloatFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/FloatFormField.class.php
index 63ef4999eae..2ab9378c0dd 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/FloatFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/FloatFormField.class.php
@@ -16,6 +16,7 @@ class FloatFormField extends AbstractNumericFormField
 {
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IAttributeFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IAttributeFormField.class.php
index 446b4ca7911..9d159eeb4a4 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IAttributeFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IAttributeFormField.class.php
@@ -21,21 +21,23 @@ interface IAttributeFormField extends IFormField
     /**
      * Returns the value of the additional attribute of the actual field element with the given name.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid or no such attribute exists
-     * @return      mixed
+     * @throws \InvalidArgumentException if the given attribute is invalid or no such attribute exists
+     * @return mixed
      */
     public function getFieldAttribute(string $name);
 
     /**
      * Returns all additional attributes of the actual field element.
+     *
+     * @return array<string, string>
      */
     public function getFieldAttributes(): array;
 
     /**
      * Adds the given additional attribute to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given attribute is invalid
+     * @return static this form field
      */
     public function fieldAttribute(string $name, ?string $value = null);
 
@@ -43,7 +45,7 @@ public function fieldAttribute(string $name, ?string $value = null);
      * Returns `true` if an additional attribute of the actual field element with the given name exists and returns
      * false` otherwise.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
+     * @throws \InvalidArgumentException if the given attribute is invalid
      */
     public function hasFieldAttribute(string $name): bool;
 
@@ -52,8 +54,8 @@ public function hasFieldAttribute(string $name): bool;
      *
      * If the actual field element does not have the given attribute, this method silently ignores that fact.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given attribute is invalid
+     * @return static this form field
      */
     public function removeFieldAttribute(string $name);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php
index 2b7f9b835b2..b2168f22b26 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ICssClassFormField.class.php
@@ -15,21 +15,24 @@ interface ICssClassFormField extends IFormField
     /**
      * Adds the given CSS class to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given class is invalid
+     * @return static this form field
      */
     public function addFieldClass(string $class);
 
     /**
      * Adds the given CSS classes to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if any of the given classes is invalid
-     * @return      static                          this form field
+     * @param string[] $classes
+     * @return static this form field
+     * @throws \InvalidArgumentException if any of the given classes is invalid
      */
     public function addFieldClasses(array $classes);
 
     /**
      * Returns all CSS classes of the actual field element.
+     *
+     * @return string[]
      */
     public function getFieldClasses(): array;
 
@@ -37,7 +40,7 @@ public function getFieldClasses(): array;
      * Returns `true` if a CSS class of the actual field element with the given name exists and
      * returns `false` otherwise.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function hasFieldClass(string $class): bool;
 
@@ -46,8 +49,8 @@ public function hasFieldClass(string $class): bool;
      *
      * If the actual field element does not have the given CSS class, this method silently ignores that fact.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given class is invalid
+     * @return static this form field
      */
     public function removeFieldClass(string $class);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IFormField.class.php
index 41c7e43001f..571f55bf8e2 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IFormField.class.php
@@ -22,7 +22,7 @@ interface IFormField extends IFormChildNode, IFormElement
      * Adds the given validation error to this field and returns this field.
      *
      * @param IFormFieldValidationError $error validation error
-     * @return  static                  this field
+     * @return static this field
      */
     public function addValidationError(IFormFieldValidationError $error);
 
@@ -30,7 +30,7 @@ public function addValidationError(IFormFieldValidationError $error);
      * Adds the given validation error to this field and returns this field.
      *
      * @param IFormFieldValidator $validator
-     * @return  static          this field
+     * @return static this field
      */
     public function addValidator(IFormFieldValidator $validator);
 
@@ -38,7 +38,7 @@ public function addValidator(IFormFieldValidator $validator);
      * Returns the html representation of the form field only without any of the surrounding
      * structural html elements.
      *
-     * @return  string      html representation of node
+     * @return string html representation of node
      */
     public function getFieldHtml();
 
@@ -46,7 +46,7 @@ public function getFieldHtml();
      * Returns the name of the JavaScript data handler module for this form field or `null` if
      * there is no such module.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getJavaScriptDataHandlerModule();
 
@@ -55,7 +55,7 @@ public function getJavaScriptDataHandlerModule();
      *
      * If no object property has been explicitly set, the field's id is returned.
      *
-     * @return  string
+     * @return string
      */
     public function getObjectProperty();
 
@@ -68,28 +68,28 @@ public function getObjectProperty();
      * in the database, this method is expected to call `getValue()`
      * internally.
      *
-     * @return  mixed
+     * @return mixed
      */
     public function getSaveValue();
 
     /**
      * Returns the validation errors of this field.
      *
-     * @return  IFormFieldValidationError[] field validation errors
+     * @return IFormFieldValidationError[] field validation errors
      */
     public function getValidationErrors();
 
     /**
      * Returns all field value validators of this field.
      *
-     * @return  IFormFieldValidator[]       field value validators of this field
+     * @return IFormFieldValidator[] field value validators of this field
      */
     public function getValidators();
 
     /**
      * Returns the value of this field or `null` if no value has been set.
      *
-     * @return  mixed
+     * @return mixed
      */
     public function getValue();
 
@@ -98,9 +98,9 @@ public function getValue();
      * returns `false` otherwise.
      *
      * @param string $validatorId id of the checked validator
-     * @return  bool
+     * @return bool
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function hasValidator($validatorId);
 
@@ -113,7 +113,7 @@ public function hasValidator($validatorId);
      * `IFormFieldDataProcessor` object to the form document's data processor.
      * A suitable place to add the processor is the `parent()`
      *
-     * @return  bool
+     * @return bool
      */
     public function hasSaveValue();
 
@@ -121,7 +121,7 @@ public function hasSaveValue();
      * Returns `true` if this field has to be filled out and returns `false` otherwise.
      * By default, fields do not have to be filled out.
      *
-     * @return  bool
+     * @return bool
      */
     public function isRequired();
 
@@ -132,10 +132,10 @@ public function isRequired();
      * It is important to extract the value from the `$data` array instead of getting it directly
      * from the object as the entries of `$data` have been processed by the data processors.
      *
-     * @param array $data object data
+     * @param array<string, mixed> $data object data
      * @param IStorableObject $object updated object
      * @param bool $loadValues indicates if object data is loaded
-     * @return  static                  this field
+     * @return static this field
      */
     public function updatedObject(array $data, IStorableObject $object, $loadValues = true);
 
@@ -150,16 +150,16 @@ public function updatedObject(array $data, IStorableObject $object, $loadValues
      * field dependencies to only show the appropriate field.
      *
      * @param string $objectProperty object property this field represents
-     * @return  static      this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the passed object property is no valid id
+     * @throws \InvalidArgumentException if the passed object property is no valid id
      */
     public function objectProperty($objectProperty);
 
     /**
      * Reads the value of this field from request data and return this field.
      *
-     * @return  static      this field
+     * @return static this field
      */
     public function readValue();
 
@@ -167,9 +167,9 @@ public function readValue();
      * Removes the field value validator with the given id and returns this field.
      *
      * @param string $validatorId id of the removed validator
-     * @return  static              this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid or no such validator exists
+     * @throws \InvalidArgumentException if the given id is invalid or no such validator exists
      */
     public function removeValidator($validatorId);
 
@@ -177,7 +177,7 @@ public function removeValidator($validatorId);
      * Sets whether it is required to fill out this field and returns this field.
      *
      * @param bool $required determines if field has to be filled out
-     * @return  static              this field
+     * @return static this field
      */
     public function required($required = true);
 
@@ -185,7 +185,7 @@ public function required($required = true);
      * Sets the value of this field and returns this field.
      *
      * @param mixed $value new field value
-     * @return  static              this field
+     * @return static this field
      *
      * @throws  \InvalidArgumentException   if the given value is of an invalid type or otherwise is invalid
      */
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IMaximumLengthFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IMaximumLengthFormField.class.php
index cbecf72716b..6d7a635d3df 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IMaximumLengthFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IMaximumLengthFormField.class.php
@@ -18,7 +18,7 @@ interface IMaximumLengthFormField extends IFormField
      * Returns the maximum length of the values of this field or `null` if no maximum
      * length has been set.
      *
-     * @return  null|int
+     * @return ?int
      */
     public function getMaximumLength();
 
@@ -26,8 +26,8 @@ public function getMaximumLength();
      * Sets the maximum length of the values of this field. If `null` is passed, the
      * maximum length is removed.
      *
-     * @param null|int $maximumLength maximum field value length
-     * @return  static              this field
+     * @param ?int $maximumLength maximum field value length
+     * @return static this field
      *
      * @throws  \InvalidArgumentException   if the given maximum length is no integer or otherwise invalid
      */
@@ -37,7 +37,8 @@ public function maximumLength($maximumLength = null);
      * Validates the maximum length of the given text.
      *
      * @param string $text validated text
-     * @param null|Language $language language of the validated text
+     * @param ?Language $language language of the validated text
+     * @return void
      */
     public function validateMaximumLength($text, ?Language $language = null);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IMinimumLengthFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IMinimumLengthFormField.class.php
index 6ce46b19e13..543e9869648 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IMinimumLengthFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IMinimumLengthFormField.class.php
@@ -18,7 +18,7 @@ interface IMinimumLengthFormField extends IFormField
      * Returns the minimum length of the values of this field or `null` if no minimum
      * length has been set.
      *
-     * @return  null|int
+     * @return ?int
      */
     public function getMinimumLength();
 
@@ -26,10 +26,10 @@ public function getMinimumLength();
      * Sets the minimum length of the values of this field. If `null` is passed, the
      * minimum length is removed.
      *
-     * @param null|int $minimumLength minimum field value length
-     * @return  static              this field
+     * @param ?int $minimumLength minimum field value length
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given minimum length is no int or otherwise invalid
+     * @throws \InvalidArgumentException if the given minimum length is no int or otherwise invalid
      */
     public function minimumLength($minimumLength = null);
 
@@ -37,7 +37,8 @@ public function minimumLength($minimumLength = null);
      * Validates the minimum length of the given text.
      *
      * @param string $text validated text
-     * @param null|Language $language language of the validated text
+     * @param ?Language $language language of the validated text
+     * @return void
      */
     public function validateMinimumLength($text, ?Language $language = null);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IPlaceholderFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IPlaceholderFormField.class.php
index d60efea2ae7..ce3a3f085cc 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IPlaceholderFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IPlaceholderFormField.class.php
@@ -16,7 +16,7 @@ interface IPlaceholderFormField extends IFormField
      * Returns the placeholder value of this field or `null` if no placeholder has
      * been set.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getPlaceholder();
 
@@ -25,11 +25,11 @@ public function getPlaceholder();
      * and returns this element. If `null` is passed, the placeholder value is
      * removed.
      *
-     * @param null|string $languageItem language item containing the placeholder or `null` to unset placeholder
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this field
+     * @param ?string $languageItem language item containing the placeholder or `null` to unset placeholder
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given value is invalid
+     * @throws \InvalidArgumentException if the given value is invalid
      */
     public function placeholder($languageItem = null, array $variables = []);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ISelectionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ISelectionFormField.class.php
index 7af74f3f03a..99167ee0b46 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ISelectionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ISelectionFormField.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\form\builder\field;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -17,19 +18,17 @@ interface ISelectionFormField extends IFormField
     /**
      * Returns a structured array that can be used to generate the form field output.
      *
-     * Array elements are `value`, `label`, and `depth`.
-     *
-     * @return  array
-     * @throws  \BadMethodCallException     if nested options are not supported
+     * @return ?array<string|int, array{label: string, value: mixed, depth: int, isSelectable: bool}>
+     * @throws \BadMethodCallException if nested options are not supported
      */
     public function getNestedOptions();
 
     /**
      * Returns the possible options of this field.
      *
-     * @return  array
+     * @return mixed[]
      *
-     * @throws  \BadMethodCallException     if no options have been set
+     * @throws \BadMethodCallException if no options have been set
      */
     public function getOptions();
 
@@ -51,20 +50,20 @@ public function getOptions();
      * callable returning an array. Each array value must be an array with the
      * following entries: `depth`, `label`, and `value`.
      *
-     * @param array|callable|DatabaseObjectList $options selectable options or callable returning the options
+     * @param mixed[]|callable|DatabaseObjectList<DatabaseObject> $options selectable options or callable returning the options
      * @param bool $nestedOptions is `true` if the passed options are nested options
      * @param bool $labelLanguageItems is `true` if the labels should be treated as language items if possible
-     * @return  static                  this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException       if given options are no array or callable or otherwise invalid
-     * @throws  \UnexpectedValueException       if callable does not return an array
+     * @throws \InvalidArgumentException if given options are no array or callable or otherwise invalid
+     * @throws \UnexpectedValueException if callable does not return an array
      */
     public function options($options, $nestedOptions = false, $labelLanguageItems = true);
 
     /**
      * Returns `true` if the field class supports nested options and `false` otherwise.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsNestedOptions();
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ISuffixedFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ISuffixedFormField.class.php
index 8bbeaa59530..38b4bdbb06a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ISuffixedFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ISuffixedFormField.class.php
@@ -15,7 +15,7 @@ interface ISuffixedFormField extends IFormField
     /**
      * Returns the suffix of this field or `null` if no suffix has been set.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getSuffix();
 
@@ -23,11 +23,11 @@ public function getSuffix();
      * Sets the suffix of this field using the given language item and returns
      * this element. If `null` is passed, the suffix is removed.
      *
-     * @param null|string $languageItem language item containing the suffix or `null` to unset suffix
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this field
+     * @param ?string $languageItem language item containing the suffix or `null` to unset suffix
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given language item is invalid
+     * @throws \InvalidArgumentException if the given language item is invalid
      */
     public function suffix($languageItem = null, array $variables = []);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IntegerFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IntegerFormField.class.php
index cb082f340ee..2b18371ae77 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IntegerFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IntegerFormField.class.php
@@ -21,6 +21,7 @@ class IntegerFormField extends AbstractNumericFormField
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/IsDisabledFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/IsDisabledFormField.class.php
index a4c478ac3b2..28ee53cc55a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/IsDisabledFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/IsDisabledFormField.class.php
@@ -16,6 +16,7 @@ class IsDisabledFormField extends BooleanFormField
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getDefaultId()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/MultilineTextFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/MultilineTextFormField.class.php
index a7e6eab4634..0364e32a57a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/MultilineTextFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/MultilineTextFormField.class.php
@@ -25,6 +25,7 @@ class MultilineTextFormField extends TextFormField
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/PagesFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/PagesFormField.class.php
index 7b7dd0e0a80..bc417a6a751 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/PagesFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/PagesFormField.class.php
@@ -35,7 +35,7 @@ public function __construct()
     }
 
     #[\Override]
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'pageIDs';
     }
@@ -57,6 +57,9 @@ public function getInvertedLabel(): string
         return $this->invertedLabel;
     }
 
+    /**
+     * @param array<string, mixed> $variables
+    */
     public function invertedLabel(string $languageItem, array $variables = []): self
     {
         $this->invertedLabel = WCF::getLanguage()->getDynamicVariable($languageItem, $variables);
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/PasswordFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/PasswordFormField.class.php
index 778f4ca5f1a..cc21238b59f 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/PasswordFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/PasswordFormField.class.php
@@ -68,7 +68,7 @@ public function __construct()
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
@@ -120,6 +120,7 @@ public function passwordStrengthMeter(bool $passwordStrengthMeter = true): self
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getDefaultId()
     {
@@ -128,6 +129,7 @@ protected static function getDefaultId()
 
     /**
      * @inheritDoc
+     * @return string[]
      */
     protected function getValidAutoCompleteTokens(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/RatingFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/RatingFormField.class.php
index 9e6f9937d98..7dfed6b6aac 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/RatingFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/RatingFormField.class.php
@@ -116,7 +116,7 @@ public function readValue()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'rating';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/ShowOrderFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/ShowOrderFormField.class.php
index b4c61799a82..91940054a81 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/ShowOrderFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/ShowOrderFormField.class.php
@@ -117,7 +117,7 @@ public function value($value)
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'showOrder';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/SortOrderFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/SortOrderFormField.class.php
index abc80c8700f..92deffbedf2 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/SortOrderFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/SortOrderFormField.class.php
@@ -32,7 +32,7 @@ public function __construct()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'sortOrder';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TAttributeFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TAttributeFormField.class.php
index 391d5e3c99a..c240d766b6f 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TAttributeFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TAttributeFormField.class.php
@@ -15,7 +15,7 @@
 trait TAttributeFormField
 {
     /**
-     * @var string[]
+     * @var array<string, mixed>
      */
     protected $fieldAttributes = [];
 
@@ -38,8 +38,8 @@ trait TAttributeFormField
     /**
      * Returns the value of the additional attribute of the actual field element with the given name.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid or no such attribute exists
-     * @return      mixed
+     * @throws \InvalidArgumentException if the given attribute is invalid or no such attribute exists
+     * @return mixed
      */
     public function getFieldAttribute(string $name)
     {
@@ -52,6 +52,8 @@ public function getFieldAttribute(string $name)
 
     /**
      * Returns all additional attributes of the actual field element.
+     *
+     * @return array<string, mixed>
      */
     public function getFieldAttributes(): array
     {
@@ -61,8 +63,8 @@ public function getFieldAttributes(): array
     /**
      * Adds the given additional attribute to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given attribute is invalid
+     * @return static this form field
      */
     public function fieldAttribute(string $name, ?string $value = null)
     {
@@ -77,7 +79,7 @@ public function fieldAttribute(string $name, ?string $value = null)
      * Returns `true` if an additional attribute of the actual field element with the given name exists and returns
      * false` otherwise.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
+     * @throws \InvalidArgumentException if the given attribute is invalid
      */
     public function hasFieldAttribute(string $name): bool
     {
@@ -91,8 +93,8 @@ public function hasFieldAttribute(string $name): bool
      *
      * If the actual field element does not have the given attribute, this method silently ignores that fact.
      *
-     * @throws      \InvalidArgumentException       if the given attribute is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given attribute is invalid
+     * @return static this form field
      */
     public function removeFieldAttribute(string $name)
     {
@@ -106,7 +108,7 @@ public function removeFieldAttribute(string $name)
     /**
      * Returns a list of attributes that are not accessible via the field attribute methods.
      *
-     * @return      string[]
+     * @return string[]
      */
     protected static function getReservedFieldAttributes(): array
     {
@@ -129,16 +131,18 @@ protected static function getReservedFieldAttributes(): array
      * Checks if the given name is valid attribute name.
      *
      * @param string $name checked argument name
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given attribute name is invalid
-     * @see         IFormNode::validateAttribute()
+     * @throws \InvalidArgumentException if the given attribute name is invalid
+     * @see IFormNode::validateAttribute()
      */
     abstract public static function validateAttribute($name);
 
     /**
      * Checks if the given name is a valid additional attribute name.
      *
-     * @throws      \InvalidArgumentException       if the given additional attribute name is invalid
+     * @return void
+     * @throws \InvalidArgumentException if the given additional attribute name is invalid
      */
     public static function validateFieldAttribute(string $name)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TAutoCompleteFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TAutoCompleteFormField.class.php
index bec123e85fd..24438ed2889 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TAutoCompleteFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TAutoCompleteFormField.class.php
@@ -57,6 +57,7 @@ public function getAutoComplete(): ?string
     /**
      * Returns all valid `autocomplete` tokens.
      *
+     * @return string[]
      * @see https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#inappropriate-for-the-control
      */
     protected function getValidAutoCompleteTokens(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php
index ea9680d16fd..cff40654166 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TCssClassFormField.class.php
@@ -21,8 +21,8 @@ trait TCssClassFormField
     /**
      * Adds the given CSS class to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given class is invalid
+     * @return static this form field
      */
     public function addFieldClass(string $class)
     {
@@ -38,8 +38,9 @@ public function addFieldClass(string $class)
     /**
      * Adds the given CSS classes to the actual field element and returns this field.
      *
-     * @throws      \InvalidArgumentException       if any of the given classes is invalid
-     * @return      static                          this form field
+     * @param string[] $classes
+     * @return static this form field
+     * @throws \InvalidArgumentException if any of the given classes is invalid
      */
     public function addFieldClasses(array $classes)
     {
@@ -52,6 +53,8 @@ public function addFieldClasses(array $classes)
 
     /**
      * Returns all CSS classes of the actual field element.
+     *
+     * @return string[]
      */
     public function getFieldClasses(): array
     {
@@ -62,7 +65,7 @@ public function getFieldClasses(): array
      * Returns `true` if a CSS class of the actual field element with the given name exists and
      * returns `false` otherwise.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     public function hasFieldClass(string $class): bool
     {
@@ -76,8 +79,8 @@ public function hasFieldClass(string $class): bool
      *
      * If the actual field element does not have the given CSS class, this method silently ignores that fact.
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
-     * @return      static                          this form field
+     * @throws \InvalidArgumentException if the given class is invalid
+     * @return static this form field
      */
     public function removeFieldClass(string $class)
     {
@@ -95,8 +98,9 @@ public function removeFieldClass(string $class)
      * Checks if the given parameter class is a valid CSS class.
      *
      * @param string $class checked class
+     * @return void
      *
-     * @throws      \InvalidArgumentException       if the given class is invalid
+     * @throws \InvalidArgumentException if the given class is invalid
      */
     abstract public static function validateClass($class);
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TI18nFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TI18nFormField.class.php
index dc3d4244d0d..c66a4d5c52b 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TI18nFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TI18nFormField.class.php
@@ -44,7 +44,7 @@ trait TI18nFormField
 
     /**
      * pattern for the language item used to save the i18n values
-     * @var null|string
+     * @var ?string
      */
     protected $languageItemPattern;
 
@@ -52,7 +52,7 @@ trait TI18nFormField
      * Returns additional template variables used to generate the html representation
      * of this node.
      *
-     * @return  array       additional template variables
+     * @return array{}|array{elementIdentifier: string, forceSelection: bool}
      */
     public function getHtmlVariables()
     {
@@ -71,9 +71,9 @@ public function getHtmlVariables()
     /**
      * Returns the pattern for the language item used to save the i18n values.
      *
-     * @return  string              language item pattern
+     * @return string language item pattern
      *
-     * @throws  \BadMethodCallException     if i18n is disabled for this field or no language item has been set
+     * @throws \BadMethodCallException if i18n is disabled for this field or no language item has been set
      */
     public function getLanguageItemPattern()
     {
@@ -99,7 +99,7 @@ public function getLanguageItemPattern()
      * in the database, this method is expected to call `getValue()`
      * internally.
      *
-     * @return  mixed
+     * @return mixed
      */
     public function getSaveValue()
     {
@@ -115,7 +115,7 @@ public function getSaveValue()
     /**
      * Returns the value of this field or `null` if no value has been set.
      *
-     * @return  mixed
+     * @return mixed
      */
     public function getValue()
     {
@@ -148,7 +148,7 @@ public function getValue()
      * Returns `true` if the current field value is a i18n value and returns `false`
      * otherwise or if no value has been set.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasI18nValues()
     {
@@ -159,7 +159,7 @@ public function hasI18nValues()
      * Returns `true` if the current field value is a plain value and returns `false`
      * otherwise or if no value has been set.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasPlainValue()
     {
@@ -175,7 +175,7 @@ public function hasPlainValue()
      * `IFormFieldDataProcessor` object to the form document's data processor.
      * A suitable place to add the processor is the `parent()`
      *
-     * @return  bool
+     * @return bool
      */
     public function hasSaveValue()
     {
@@ -186,7 +186,7 @@ public function hasSaveValue()
      * Sets whether this field is supports i18n input and returns this field.
      *
      * @param bool $i18n determines if field supports i18n input
-     * @return  II18nFormField          this field
+     * @return II18nFormField this field
      */
     public function i18n($i18n = true)
     {
@@ -214,7 +214,7 @@ public function getJavaScriptDataHandlerModule(): string
      * ensure that i18n support is enabled.
      *
      * @param bool $i18nRequired determines if field value must be i18n input
-     * @return  static                  this field
+     * @return static this field
      */
     public function i18nRequired($i18nRequired = true)
     {
@@ -228,7 +228,7 @@ public function i18nRequired($i18nRequired = true)
      * Returns `true` if this field supports i18n input and returns `false` otherwise.
      * By default, fields do not support i18n input.
      *
-     * @return  bool
+     * @return bool
      */
     public function isI18n()
     {
@@ -239,7 +239,7 @@ public function isI18n()
      * Returns `true` if this field's value must be i18n input and returns `false` otherwise.
      * By default, fields do not support i18n input.
      *
-     * @return  bool
+     * @return bool
      */
     public function isI18nRequired()
     {
@@ -251,10 +251,10 @@ public function isI18nRequired()
      * and returns this field.
      *
      * @param string $pattern language item pattern
-     * @return  II18nFormField          this field
+     * @return II18nFormField this field
      *
-     * @throws  \BadMethodCallException     if i18n is disabled for this field
-     * @throws  \InvalidArgumentException   if the given pattern is invalid
+     * @throws \BadMethodCallException if i18n is disabled for this field
+     * @throws \InvalidArgumentException if the given pattern is invalid
      */
     public function languageItemPattern($pattern)
     {
@@ -304,9 +304,9 @@ public function updatedObject(array $data, IStorableObject $object, $loadValues
      * This method enables this node to perform actions that require the whole document having
      * finished constructing itself and every parent-child relationship being established.
      *
-     * @return  IFormNode           this node
+     * @return IFormNode this node
      *
-     * @throws  \BadMethodCallException     if this node has already been populated
+     * @throws \BadMethodCallException if this node has already been populated
      */
     public function populate()
     {
@@ -336,7 +336,7 @@ function (IFormDocument $document, array $parameters) {
     /**
      * Reads the value of this field from request data and return this field.
      *
-     * @return  IFormField  this field
+     * @return IFormField this field
      */
     public function readValue()
     {
@@ -360,6 +360,7 @@ public function readValue()
      * field values.
      *
      * @param string $value set value
+     * @return void
      */
     protected function setStringValue($value)
     {
@@ -390,7 +391,7 @@ protected function setStringValue($value)
      * Sets the value of this field and returns this field.
      *
      * @param string|string[] $value new field value
-     * @return  static                  this field
+     * @return static this field
      *
      * @throws  \InvalidArgumentException       if the given value is of an invalid type or otherwise is invalid
      */
@@ -422,6 +423,8 @@ public function value($value)
      *
      * Note: A `IFormParentNode` object may only return `true` if all of its child
      * nodes are valid. A `IFormField` object is valid if its value is valid.
+     *
+     * @return void
      */
     public function validate()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TInputModeFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TInputModeFormField.class.php
index 5c39eaf8bab..0a755894893 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TInputModeFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TInputModeFormField.class.php
@@ -46,6 +46,8 @@ public function inputMode(?string $inputMode)
 
     /**
      * Returns all valid `inputmode` tokens.
+     *
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TMaximumFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TMaximumFormField.class.php
index cbc28f7eb1f..a3cccd285f2 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TMaximumFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TMaximumFormField.class.php
@@ -22,7 +22,7 @@ trait TMaximumFormField
      * Returns the maximum of the values of this field or `null` if no maximum
      * has been set.
      *
-     * @return  null|int|float
+     * @return null|int|float
      */
     public function getMaximum()
     {
@@ -34,9 +34,9 @@ public function getMaximum()
      * maximum is removed.
      *
      * @param null|int|float $maximum maximum field value
-     * @return  static              this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given maximum is no number or otherwise invalid
+     * @throws \InvalidArgumentException if the given maximum is no number or otherwise invalid
      */
     public function maximum($maximum = null)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TMaximumLengthFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TMaximumLengthFormField.class.php
index abb671578b7..41b078364cb 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TMaximumLengthFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TMaximumLengthFormField.class.php
@@ -17,7 +17,7 @@ trait TMaximumLengthFormField
 {
     /**
      * maximum length of the field value
-     * @var null|int
+     * @var ?int
      */
     protected $maximumLength;
 
@@ -25,7 +25,7 @@ trait TMaximumLengthFormField
      * Returns the maximum length of the values of this field or `null` if no placeholder
      * has been set.
      *
-     * @return  null|int
+     * @return ?int
      */
     public function getMaximumLength()
     {
@@ -36,10 +36,10 @@ public function getMaximumLength()
      * Sets the maximum length of the values of this field. If `null` is passed, the
      * maximum length is removed.
      *
-     * @param null|int $maximumLength maximum field value length
-     * @return  static              this field
+     * @param ?int $maximumLength maximum field value length
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given maximum length is no integer or otherwise invalid
+     * @throws \InvalidArgumentException if the given maximum length is no integer or otherwise invalid
      */
     public function maximumLength($maximumLength = null)
     {
@@ -75,8 +75,9 @@ public function maximumLength($maximumLength = null)
      * Validates the maximum length of the given text.
      *
      * @param string $text validated text
-     * @param null|Language $language language of the validated text
+     * @param ?Language $language language of the validated text
      * @param string $errorLanguageItem
+     * @return void
      */
     public function validateMaximumLength(
         $text,
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TMinimumLengthFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TMinimumLengthFormField.class.php
index eb076c570d8..203e4ef23a5 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TMinimumLengthFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TMinimumLengthFormField.class.php
@@ -17,7 +17,7 @@ trait TMinimumLengthFormField
 {
     /**
      * minimum length of the field value
-     * @var null|int
+     * @var ?int
      */
     protected $minimumLength;
 
@@ -25,7 +25,7 @@ trait TMinimumLengthFormField
      * Returns the minimum length of the values of this field or `null` if no placeholder
      * has been set.
      *
-     * @return  null|int
+     * @return ?int
      */
     public function getMinimumLength()
     {
@@ -36,10 +36,10 @@ public function getMinimumLength()
      * Sets the minimum length of the values of this field. If `null` is passed, the
      * minimum length is removed.
      *
-     * @param null|int $minimumLength minimum field value length
-     * @return  static              this field
+     * @param ?int $minimumLength minimum field value length
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given minimum length is no integer or otherwise invalid
+     * @throws \InvalidArgumentException if the given minimum length is no integer or otherwise invalid
      */
     public function minimumLength($minimumLength = null)
     {
@@ -75,7 +75,8 @@ public function minimumLength($minimumLength = null)
      * Validates the minimum length of the given text.
      *
      * @param string $text validated text
-     * @param null|Language $language language of the validated text
+     * @param ?Language $language language of the validated text
+     * @return void
      */
     public function validateMinimumLength($text, ?Language $language = null)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TPlaceholderFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TPlaceholderFormField.class.php
index 81e7dcee66e..e58d15293c1 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TPlaceholderFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TPlaceholderFormField.class.php
@@ -24,7 +24,7 @@ trait TPlaceholderFormField
      * Returns the placeholder value of this field or `null` if no placeholder has
      * been set.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getPlaceholder()
     {
@@ -36,11 +36,11 @@ public function getPlaceholder()
      * and returns this element. If `null` is passed, the placeholder value is
      * removed.
      *
-     * @param null|string $languageItem language item containing the placeholder or `null` to unset description
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this field
+     * @param ?string $languageItem language item containing the placeholder or `null` to unset description
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given value is no or otherwise invalid
+     * @throws \InvalidArgumentException if the given value is no or otherwise invalid
      */
     public function placeholder($languageItem = null, array $variables = [])
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
index 57aa8b1fe0b..47261e7893c 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TSelectionFormField.class.php
@@ -20,23 +20,21 @@ trait TSelectionFormField
 {
     /**
      * structured options array used to generate the form field output
-     * @var null|array
+     * @var ?array<string|int, array{label: string, value: mixed, depth: int, isSelectable: bool}>
      */
     protected $nestedOptions;
 
     /**
      * possible options to select
-     * @var null|array
+     * @var ?mixed[]
      */
     protected $options;
 
     /**
      * Returns a structured array that can be used to generate the form field output.
      *
-     * Array elements are `value`, `label`, and `depth`.
-     *
-     * @return  array
-     * @throws  \BadMethodCallException     if nested options are not supported
+     * @return array<string|int, array{label: string, value: mixed, depth: int, isSelectable: bool}>
+     * @throws \BadMethodCallException if nested options are not supported
      */
     public function getNestedOptions()
     {
@@ -50,9 +48,9 @@ public function getNestedOptions()
     /**
      * Returns the selectable options of this field.
      *
-     * @return  array
+     * @return mixed[]
      *
-     * @throws  \BadMethodCallException     if no options have been set
+     * @throws \BadMethodCallException if no options have been set
      */
     public function getOptions()
     {
@@ -68,9 +66,9 @@ public function getOptions()
      *
      * If the node's availability has not been explicitly set, `true` is returned.
      *
-     * @return  bool
+     * @return bool
      *
-     * @see     IFormNode::available()
+     * @see IFormNode::available()
      */
     public function isAvailable()
     {
@@ -96,13 +94,13 @@ public function isAvailable()
      * callable returning an array. Each array value must be an array with the
      * following entries: `depth`, `label`, and `value`.
      *
-     * @param array|callable|\Traversable|DatabaseObjectList $options selectable options or callable returning the options
+     * @param array<string|int, mixed>|callable|\Traversable<mixed>|DatabaseObjectList $options selectable options or callable returning the options
      * @param bool $nestedOptions is `true` if the passed options are nested options
      * @param bool $labelLanguageItems is `true` if the labels should be treated as language items if possible
-     * @return  static                  this field
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if given options are no array or callable or otherwise invalid
-     * @throws  \UnexpectedValueException   if callable does not return an array
+     * @throws \InvalidArgumentException if given options are no array or callable or otherwise invalid
+     * @throws \UnexpectedValueException if callable does not return an array
      */
     public function options($options, $nestedOptions = false, $labelLanguageItems = true)
     {
@@ -306,7 +304,7 @@ public function options($options, $nestedOptions = false, $labelLanguageItems =
     /**
      * Returns `true` if the field class supports nested options and `false` otherwise.
      *
-     * @return  bool
+     * @return bool
      */
     public function supportsNestedOptions()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TSuffixedFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TSuffixedFormField.class.php
index ff4589fadf6..927e1dbd177 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TSuffixedFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TSuffixedFormField.class.php
@@ -16,14 +16,14 @@ trait TSuffixedFormField
 {
     /**
      * suffix of this field
-     * @var null|string
+     * @var ?string
      */
     protected $suffix;
 
     /**
      * Returns the suffix of this field or `null` if no suffix has been set.
      *
-     * @return  null|string
+     * @return ?string
      */
     public function getSuffix()
     {
@@ -34,9 +34,9 @@ public function getSuffix()
      * Sets the suffix of this field using the given language item and returns
      * this element. If `null` is passed, the suffix is removed.
      *
-     * @param null|string $languageItem language item containing the suffix or `null` to unset suffix
-     * @param array $variables additional variables used when resolving the language item
-     * @return  static              this field
+     * @param ?string $languageItem language item containing the suffix or `null` to unset suffix
+     * @param array<string, mixed> $variables additional variables used when resolving the language item
+     * @return static this field
      *
      * @throws  \InvalidArgumentException   if the given language item is no or otherwise invalid
      */
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TTextAutoCompleteFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TTextAutoCompleteFormField.class.php
index f97bf855f6f..1901d2ddd73 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TTextAutoCompleteFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TTextAutoCompleteFormField.class.php
@@ -16,6 +16,7 @@ trait TTextAutoCompleteFormField
 
     /**
      * @inheritDoc
+     * @return string[]
      */
     protected function getValidAutoCompleteTokens(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TextFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TextFormField.class.php
index d48229cdde6..59e67d3eb3a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TextFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TextFormField.class.php
@@ -60,7 +60,7 @@ public function __construct()
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
@@ -108,7 +108,8 @@ public function validate()
      * Checks the length of the given text with the given language.
      *
      * @param string $text validated text
-     * @param null|Language $language language of validated text or `null` for monolingual text
+     * @param ?Language $language language of validated text or `null` for monolingual text
+     * @return void
      */
     protected function validateText($text, ?Language $language = null)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/TitleFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/TitleFormField.class.php
index 65acb625f60..4a709ed3c0a 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/TitleFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/TitleFormField.class.php
@@ -27,7 +27,7 @@ public function __construct()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'title';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/UploadFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/UploadFormField.class.php
index e18bffde453..dc5c32837f2 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/UploadFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/UploadFormField.class.php
@@ -54,31 +54,31 @@ class UploadFormField extends AbstractFormField
 
     /**
      * maximum filesize for each uploaded file
-     * @var null|number
+     * @var ?int
      */
     protected $maximumFilesize;
 
     /**
      * minimum image width for each uploaded file
-     * @var null|number
+     * @var ?int
      */
     protected $minimumImageWidth;
 
     /**
      * maximum image width for each uploaded file
-     * @var null|number
+     * @var ?int
      */
     protected $maximumImageWidth;
 
     /**
      * minimum image height for each uploaded file
-     * @var null|number
+     * @var ?int
      */
     protected $minimumImageHeight;
 
     /**
      * maximum image height for each uploaded file
-     * @var null|number
+     * @var ?int
      */
     protected $maximumImageHeight;
 
@@ -89,7 +89,7 @@ class UploadFormField extends AbstractFormField
 
     /**
      * Array of temporary values, which are assigned, after the method `populate` are called.
-     * @var array
+     * @var UploadFile[]
      */
     private $values = [];
 
@@ -116,6 +116,8 @@ class UploadFormField extends AbstractFormField
 
     /**
      * Unregisters the current field in the upload handler.
+     *
+     * @return void
      */
     private function unregisterField()
     {
@@ -624,7 +626,9 @@ protected function registerField(): void
     /**
      * @inheritDoc
      *
-     * @throws      \LogicException       if the field has already been initialized
+     * @param ?int $maximum
+     * @return static
+     * @throws \LogicException if the field has already been initialized
      */
     public function maximum($maximum = null)
     {
@@ -641,14 +645,15 @@ public function maximum($maximum = null)
      * Sets the maximum filesize for each upload. If `null` is passed, the
      * maximum filesize is removed.
      *
-     * @param null|number $maximumFilesize maximum filesize
-     * @return  static                      this field
+     * @param ?int $maximumFilesize maximum filesize
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given maximum filesize is no number or otherwise invalid
+     * @throws \InvalidArgumentException if the given maximum filesize is no number or otherwise invalid
      */
     public function maximumFilesize($maximumFilesize = null)
     {
         if ($maximumFilesize !== null) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_numeric($maximumFilesize)) {
                 throw new \InvalidArgumentException(
                     "Given maximum filesize is no int, '" . \gettype($maximumFilesize) . "' given for field '{$this->getId()}'."
@@ -665,7 +670,7 @@ public function maximumFilesize($maximumFilesize = null)
      * Returns the maximum filesize of each file or `null` if no maximum filesize
      * has been set.
      *
-     * @return  null|number
+     * @return ?int
      */
     public function getMaximumFilesize()
     {
@@ -676,11 +681,11 @@ public function getMaximumFilesize()
      * Sets the minimum image width for each uploaded file. If `null` is passed, the
      * minimum image width is removed.
      *
-     * @param null|number $minimumImageWidth the mimimum image width
-     * @return  static                     this field
+     * @param ?int $minimumImageWidth the mimimum image width
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given mimimum image width is no number or otherwise invalid
-     * @throws  \LogicException                  if the form field is not marked as image only
+     * @throws \InvalidArgumentException if the given mimimum image width is no number or otherwise invalid
+     * @throws \LogicException if the form field is not marked as image only
      */
     public function minimumImageWidth($minimumImageWidth = null)
     {
@@ -689,6 +694,7 @@ public function minimumImageWidth($minimumImageWidth = null)
         }
 
         if ($minimumImageWidth !== null) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_numeric($minimumImageWidth)) {
                 throw new \InvalidArgumentException(
                     "Given minimum image width is no int, '" . \gettype($minimumImageWidth) . "' given for field '{$this->getId()}'."
@@ -712,7 +718,7 @@ public function minimumImageWidth($minimumImageWidth = null)
      * Returns the mimimum image width of each file or `null` if no mimimum image width
      * has been set.
      *
-     * @return  null|number
+     * @return ?int
      */
     public function getMinimumImageWidth()
     {
@@ -723,11 +729,11 @@ public function getMinimumImageWidth()
      * Sets the maximum image width for each uploaded file. If `null` is passed, the
      * maximum image width is removed.
      *
-     * @param null|number $maximumImageWidth the maximum image width
-     * @return  static                     this field
+     * @param ?int $maximumImageWidth the maximum image width
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given mimimum image width is no number or otherwise invalid
-     * @throws  \LogicException                  if the form field is not marked as image only
+     * @throws \InvalidArgumentException if the given mimimum image width is no number or otherwise invalid
+     * @throws \LogicException if the form field is not marked as image only
      */
     public function maximumImageWidth($maximumImageWidth = null)
     {
@@ -736,6 +742,7 @@ public function maximumImageWidth($maximumImageWidth = null)
         }
 
         if ($maximumImageWidth !== null) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_numeric($maximumImageWidth)) {
                 throw new \InvalidArgumentException(
                     "Given maximum image width is no int, '" . \gettype($maximumImageWidth) . "' given for field '{$this->getId()}'."
@@ -759,7 +766,7 @@ public function maximumImageWidth($maximumImageWidth = null)
      * Returns the maximum image width of each file or `null` if no maximum image width
      * has been set.
      *
-     * @return  null|number
+     * @return ?int
      */
     public function getMaximumImageWidth()
     {
@@ -770,11 +777,11 @@ public function getMaximumImageWidth()
      * Sets the minimum image height for each uploaded file. If `null` is passed, the
      * minimum image height is removed.
      *
-     * @param null|number $minimumImageHeight the mimimum image height
-     * @return  static                      this field
+     * @param ?int $minimumImageHeight the mimimum image height
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given mimimum image height is no number or otherwise invalid
-     * @throws  \LogicException                  if the form field is not marked as image only
+     * @throws \InvalidArgumentException if the given mimimum image height is no number or otherwise invalid
+     * @throws \LogicException if the form field is not marked as image only
      */
     public function minimumImageHeight($minimumImageHeight = null)
     {
@@ -785,6 +792,7 @@ public function minimumImageHeight($minimumImageHeight = null)
         }
 
         if ($minimumImageHeight !== null) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_numeric($minimumImageHeight)) {
                 throw new \InvalidArgumentException(
                     "Given minimum image height is no int, '" . \gettype($minimumImageHeight) . "' given for field '{$this->getId()}'."
@@ -808,7 +816,7 @@ public function minimumImageHeight($minimumImageHeight = null)
      * Returns the mimimum image height of each file or `null` if no mimimum image height
      * has been set.
      *
-     * @return  null|number
+     * @return ?int
      */
     public function getMinimumImageHeight()
     {
@@ -819,11 +827,11 @@ public function getMinimumImageHeight()
      * Sets the maximum image height for each uploaded file. If `null` is passed, the
      * maximum image height is removed.
      *
-     * @param null|number $maximumImageHeight the maximum image height
-     * @return  static                     this field
+     * @param ?int $maximumImageHeight the maximum image height
+     * @return static this field
      *
-     * @throws  \InvalidArgumentException   if the given mimimum image height is no number or otherwise invalid
-     * @throws  \LogicException                  if the form field is not marked as image only
+     * @throws \InvalidArgumentException if the given mimimum image height is no number or otherwise invalid
+     * @throws \LogicException if the form field is not marked as image only
      */
     public function maximumImageHeight($maximumImageHeight = null)
     {
@@ -834,6 +842,7 @@ public function maximumImageHeight($maximumImageHeight = null)
         }
 
         if ($maximumImageHeight !== null) {
+            // @phpstan-ignore function.alreadyNarrowedType
             if (!\is_numeric($maximumImageHeight)) {
                 throw new \InvalidArgumentException(
                     "Given maximum image height is no int, '" . \gettype($maximumImageHeight) . "' given for field '{$this->getId()}'."
@@ -857,7 +866,7 @@ public function maximumImageHeight($maximumImageHeight = null)
      * Returns the maximum image height of each file or `null` if no maximum image height
      * has been set.
      *
-     * @return  null|number
+     * @return ?int
      */
     public function getMaximumImageHeight()
     {
@@ -872,9 +881,9 @@ public function getMaximumImageHeight()
      * false it will clear the acceptable types if they are `image/*`.
      *
      * @param bool $imageOnly
-     * @return  static              this field
+     * @return static this field
      *
-     * @throws       \InvalidArgumentException         if the field is not set to images only and a minimum/maximum width/height is set
+     * @throws \InvalidArgumentException if the field is not set to images only and a minimum/maximum width/height is set
      */
     public function imageOnly($imageOnly = true)
     {
@@ -928,9 +937,9 @@ public function imageOnly($imageOnly = true)
      * use this option, outside the acp or check the file whether remote code is contained.
      *
      * @param bool $allowSvgImages
-     * @return  static              this field
+     * @return static this field
      *
-     * @throws      \BadMethodCallException         if the imageOnly flag isn't set to true
+     * @throws \BadMethodCallException if the imageOnly flag isn't set to true
      */
     public function allowSvgImage($allowSvgImages = true)
     {
@@ -948,7 +957,7 @@ public function allowSvgImage($allowSvgImages = true)
     /**
      * Returns `true` if only images can be uploaded via this field and returns `false` otherwise.
      *
-     * @return  bool
+     * @return bool
      */
     public function isImageOnly()
     {
@@ -958,7 +967,7 @@ public function isImageOnly()
     /**
      * Returns true, if the field can contain svg images in the image only mode.
      *
-     * @return  bool
+     * @return bool
      */
     public function svgImageAllowed()
     {
@@ -979,9 +988,10 @@ public function svgImageAllowed()
      * - `image/*`
      * - `video/*`
      *
-     * @see         https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers
+     * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file#Unique_file_type_specifiers
      * @param string[]|null $acceptableFiles
-     * @since       5.3
+     * @return $this
+     * @since 5.3
      */
     public function setAcceptableFiles($acceptableFiles = null)
     {
@@ -993,8 +1003,8 @@ public function setAcceptableFiles($acceptableFiles = null)
     /**
      * Returns the acceptable file types.
      *
-     * @return      string[]|null
-     * @since       5.3
+     * @return string[]|null
+     * @since 5.3
      */
     public function getAcceptableFiles()
     {
@@ -1004,6 +1014,7 @@ public function getAcceptableFiles()
     /**
      * Returns the allowed file extensions or `null` if the extension is not validated.
      *
+     * @return string[]
      * @since  6.2
      */
     public function getAllowedFileExtensions(): ?array
@@ -1014,6 +1025,7 @@ public function getAllowedFileExtensions(): ?array
     /**
      * Specifies the allowed file extensions or `null` if the extension is not to be validated.
      *
+     * @param string[]|null $allowedFileExtensions
      * @since  6.2
      */
     public function setAllowedFileExtensions(?array $allowedFileExtensions = null): static
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/UrlFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/UrlFormField.class.php
index 29bbb3b7cd2..cc7b02fb2fc 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/UrlFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/UrlFormField.class.php
@@ -26,6 +26,7 @@ public function __construct()
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
@@ -38,7 +39,7 @@ protected function getValidAutoCompleteTokens(): array
     }
 
     /**
-     * @inheritDoc
+     * @return string[]
      */
     protected function getValidInputModes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/bbcode/BBCodeAttributesFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/bbcode/BBCodeAttributesFormField.class.php
index 7c7f2cc5900..e884da7c4ae 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/bbcode/BBCodeAttributesFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/bbcode/BBCodeAttributesFormField.class.php
@@ -32,7 +32,7 @@ final class BBCodeAttributesFormField extends AbstractFormField
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'attributes';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueFormFieldDependency.class.php b/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueFormFieldDependency.class.php
index 26f213dee88..360b458e3b7 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueFormFieldDependency.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueFormFieldDependency.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\form\builder\field\dependency;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -23,7 +24,7 @@ class ValueFormFieldDependency extends AbstractFormFieldDependency
 
     /**
      * possible values the field may have for the dependency to be met
-     * @var null|array
+     * @var ?array<string|int, mixed>
      */
     protected $values;
 
@@ -62,9 +63,9 @@ public function checkDependency()
     /**
      * Returns the possible values the field may have for the dependency to be met.
      *
-     * @return  array               possible field values
+     * @return array<string|int, mixed> possible field values
      *
-     * @throws  \BadMethodCallException     if no values have been set
+     * @throws \BadMethodCallException if no values have been set
      */
     public function getValues()
     {
@@ -79,7 +80,7 @@ public function getValues()
      * Returns `true` if the field value may not have any of the set values and
      * otherwise `false`.
      *
-     * @return  bool
+     * @return bool
      */
     public function isNegated()
     {
@@ -90,7 +91,7 @@ public function isNegated()
      * Sets if the field value may not have any of the set values.
      *
      * @param bool $negate
-     * @return  static      $this       this dependency
+     * @return static $this this dependency
      */
     public function negate($negate = true)
     {
@@ -102,11 +103,11 @@ public function negate($negate = true)
     /**
      * Sets the possible values the field may have for the dependency to be met.
      *
-     * @param array|callable|DatabaseObjectList $values possible field values
-     * @return  static      $this                   this dependency
+     * @param array<string|int, mixed>|callable|DatabaseObjectList<DatabaseObject> $values possible field values
+     * @return static $this this dependency
      *
-     * @throws  \InvalidArgumentException               if given value are no array, callable, DatabaseObjectList, or otherwise invalid
-     * @throws  \UnexpectedValueException               if callable does not return an array or a DatabaseObjectList
+     * @throws \InvalidArgumentException if given value are no array, callable, DatabaseObjectList, or otherwise invalid
+     * @throws \UnexpectedValueException if callable does not return an array or a DatabaseObjectList
      */
     public function values($values)
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueIntervalFormFieldDependency.class.php b/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueIntervalFormFieldDependency.class.php
index da3e8a4a458..fe7686f0218 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueIntervalFormFieldDependency.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/dependency/ValueIntervalFormFieldDependency.class.php
@@ -15,11 +15,15 @@ final class ValueIntervalFormFieldDependency extends AbstractFormFieldDependency
 {
     /**
      * maximum value of the value interval
+     *
+     * @var float|int|null
      */
     protected $maximum;
 
     /**
      * minimum value of the value interval
+     *
+     * @var float|int|null
      */
     protected $minimum;
 
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectExcludedPackagesFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectExcludedPackagesFormField.class.php
index 931c50ae916..e1f3e911cc7 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectExcludedPackagesFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectExcludedPackagesFormField.class.php
@@ -86,7 +86,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'excludedPackages';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectInstructionsFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectInstructionsFormField.class.php
index f1fb94250e6..e8751eeeea3 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectInstructionsFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectInstructionsFormField.class.php
@@ -222,7 +222,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'instructions';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectOptionalPackagesFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectOptionalPackagesFormField.class.php
index 68ee7b098fa..e0636290bae 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectOptionalPackagesFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectOptionalPackagesFormField.class.php
@@ -77,7 +77,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'optionalPackages';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectRequiredPackagesFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectRequiredPackagesFormField.class.php
index 85e328c0ecc..eca73d6c8fb 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectRequiredPackagesFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/devtools/project/DevtoolsProjectRequiredPackagesFormField.class.php
@@ -89,7 +89,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'requiredPackages';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/language/ContentLanguageFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/language/ContentLanguageFormField.class.php
index 61efcbf5a12..11253bea16d 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/language/ContentLanguageFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/language/ContentLanguageFormField.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\form\builder\field\language;
 
+use wcf\data\language\Language;
 use wcf\system\form\builder\field\AbstractFormField;
 use wcf\system\form\builder\field\IImmutableFormField;
 use wcf\system\form\builder\field\TDefaultIdFormField;
@@ -32,16 +33,13 @@ final class ContentLanguageFormField extends AbstractFormField implements IImmut
      */
     protected $templateName = 'shared_contentLanguageFormField';
 
-    /**
-     * Creates a new instance of `ContentLanguageFormField`.
-     */
     public function __construct()
     {
         $this->label('wcf.user.language');
     }
 
     /**
-     * @inheritDoc
+     * @return Language[]
      */
     public function getContentLanguages()
     {
@@ -90,7 +88,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'languageID';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/option/OptionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/option/OptionFormField.class.php
index 22ec3122d86..4a6ceb09cff 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/option/OptionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/option/OptionFormField.class.php
@@ -84,7 +84,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'options';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/tag/TagFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/tag/TagFormField.class.php
index 39ea98ee8ff..f9bdc0f71ec 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/tag/TagFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/tag/TagFormField.class.php
@@ -196,7 +196,7 @@ public function value($value)
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'tags';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/user/UserPasswordField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/user/UserPasswordField.class.php
index a2907d34086..202a358abb9 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/user/UserPasswordField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/user/UserPasswordField.class.php
@@ -60,13 +60,14 @@ public function __construct()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'password';
     }
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/user/UsernameFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/user/UsernameFormField.class.php
index 662111ba8f6..4c3feca6304 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/user/UsernameFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/user/UsernameFormField.class.php
@@ -78,6 +78,7 @@ public function __construct()
 
     /**
      * @inheritDoc
+     * @return string[]
      * @since       5.4
      */
     protected function getValidAutoCompleteTokens(): array
@@ -147,7 +148,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'username';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/user/group/option/UserGroupOptionFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/user/group/option/UserGroupOptionFormField.class.php
index c3e47fe46f2..21f2c5c2234 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/user/group/option/UserGroupOptionFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/user/group/option/UserGroupOptionFormField.class.php
@@ -74,7 +74,7 @@ public function validate()
     /**
      * @inheritDoc
      */
-    protected static function getDefaultId()
+    protected static function getDefaultId(): string
     {
         return 'permissions';
     }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidationError.class.php b/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidationError.class.php
index 829634ba99f..32472f79bdd 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidationError.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidationError.class.php
@@ -16,21 +16,19 @@ final class FormFieldValidationError implements IFormFieldValidationError
 {
     /**
      * additional error information, also used to resolve error message from language item
-     * @var array
+     * @var array<string, mixed>
      */
-    protected $information;
+    private array $information;
 
     /**
      * language item containing the error message
-     * @var string
      */
-    protected $languageItem;
+    private string $languageItem;
 
     /**
      * error type
-     * @var string
      */
-    protected $type;
+    private string $type;
 
     /**
      * @inheritDoc
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidator.class.php b/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidator.class.php
index 24298597b82..e35a07f06d5 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidator.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/validation/FormFieldValidator.class.php
@@ -82,6 +82,7 @@ public function getId()
      * Checks if the given parameter is a and a valid validator id.
      *
      * @param mixed $id checked id
+     * @return void
      *
      * @throws  \InvalidArgumentException   if the given id is invalid
      */
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidationError.class.php b/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidationError.class.php
index d39a51d53bd..32f3b11a2d4 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidationError.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidationError.class.php
@@ -18,8 +18,8 @@ interface IFormFieldValidationError
      * If no language item is given, `wcf.global.form.error.{$type}` is used.
      *
      * @param string $type error type
-     * @param null|string $languageItem language item containing the error message
-     * @param array $information additional error information, also used to resolve error message from language item
+     * @param ?string $languageItem language item containing the error message
+     * @param array<string, mixed> $information additional error information, also used to resolve error message from language item
      *
      * @throws  \InvalidArgumentException   if the given error type is invalid
      */
@@ -28,28 +28,28 @@ public function __construct($type, $languageItem = null, array $information = []
     /**
      * Returns the HTML element representing the error.
      *
-     * @return  string
+     * @return string
      */
     public function getHtml();
 
     /**
      * Returns additional information about the error.
      *
-     * @return  array       additional error information
+     * @return array<string, mixed> additional error information
      */
     public function getInformation();
 
     /**
      * Returns the message describing the validation error.
      *
-     * @return  string      error message
+     * @return string error message
      */
     public function getMessage();
 
     /**
      * Returns the type of the validation error.
      *
-     * @return  string      error type
+     * @return string error type
      */
     public function getType();
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidator.class.php b/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidator.class.php
index 79de34fed7d..aab3c76d011 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidator.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/validation/IFormFieldValidator.class.php
@@ -20,7 +20,7 @@ interface IFormFieldValidator
      * @param string $id id of the validator
      * @param callable $validator validation function
      *
-     * @throws  \InvalidArgumentException   if the given id is invalid
+     * @throws \InvalidArgumentException if the given id is invalid
      */
     public function __construct($id, callable $validator);
 
@@ -28,13 +28,14 @@ public function __construct($id, callable $validator);
      * Validates the value of the given field.
      *
      * @param IFormField $field validated field
+     * @return void
      */
     public function __invoke(IFormField $field);
 
     /**
      * Returns the id of the validator.
      *
-     * @return  string      id of the dependency
+     * @return string id of the dependency
      */
     public function getId();
 }
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygAttachmentFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygAttachmentFormField.class.php
index d430edfef21..57f828ebb54 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygAttachmentFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygAttachmentFormField.class.php
@@ -8,7 +8,6 @@
 use wcf\system\form\builder\IFormDocument;
 use wcf\system\form\builder\TWysiwygFormNode;
 use wcf\system\WCF;
-use wcf\util\StringUtil;
 
 /**
  * Represents the form field to manage attachments for a wysiwyg form container.
@@ -26,7 +25,7 @@ final class WysiwygAttachmentFormField extends AbstractFormField
 
     /**
      * attachment handler
-     * @var null|AttachmentHandler
+     * @var ?AttachmentHandler
      */
     protected $attachmentHandler;
 
@@ -57,8 +56,8 @@ public function __construct()
      * AJAX requests or by creating a new one. If the temporary hashes are read from session,
      * the session variable will be unregistered afterwards.
      *
-     * @param null|AttachmentHandler $attachmentHandler
-     * @return  WysiwygAttachmentFormField
+     * @param ?AttachmentHandler $attachmentHandler
+     * @return WysiwygAttachmentFormField
      */
     public function attachmentHandler(?AttachmentHandler $attachmentHandler = null)
     {
@@ -98,7 +97,7 @@ public function attachmentHandler(?AttachmentHandler $attachmentHandler = null)
      * Returns the attachment handler object for the uploaded attachments or `null` if no attachment
      * upload is supported.
      *
-     * @return  null|AttachmentHandler
+     * @return ?AttachmentHandler
      */
     public function getAttachmentHandler()
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygFormField.class.php b/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygFormField.class.php
index 09da3076861..3c477097309 100644
--- a/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygFormField.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/field/wysiwyg/WysiwygFormField.class.php
@@ -390,7 +390,8 @@ public function validate()
 
     /**
      * @inheritDoc
-     * @since       5.4
+     * @return string[]
+     * @since 5.4
      */
     protected static function getReservedFieldAttributes(): array
     {
diff --git a/wcfsetup/install/files/lib/system/form/builder/wysiwyg/WysiwygSmileyFormNode.class.php b/wcfsetup/install/files/lib/system/form/builder/wysiwyg/WysiwygSmileyFormNode.class.php
index eb422cd5f81..52a1c6b04b0 100644
--- a/wcfsetup/install/files/lib/system/form/builder/wysiwyg/WysiwygSmileyFormNode.class.php
+++ b/wcfsetup/install/files/lib/system/form/builder/wysiwyg/WysiwygSmileyFormNode.class.php
@@ -43,7 +43,7 @@ public function getHtml()
     /**
      * Returns the list of available smilies.
      *
-     * @return  Smiley[]
+     * @return Smiley[]
      */
     public function getSmilies()
     {
@@ -51,7 +51,7 @@ public function getSmilies()
     }
 
     /**
-     * @inheritDoc
+     * @return bool
      */
     public function hasSaveValue()
     {
@@ -59,7 +59,7 @@ public function hasSaveValue()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     public function readValue()
     {
diff --git a/wcfsetup/install/files/lib/system/form/container/MultipleSelectionFormElementContainer.class.php b/wcfsetup/install/files/lib/system/form/container/MultipleSelectionFormElementContainer.class.php
index 927d6d43fb3..76da72ff131 100644
--- a/wcfsetup/install/files/lib/system/form/container/MultipleSelectionFormElementContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/container/MultipleSelectionFormElementContainer.class.php
@@ -13,14 +13,15 @@ class MultipleSelectionFormElementContainer extends SelectionFormElementContaine
 {
     /**
      * container value
-     * @var array
+     * @var string[]
      */
     protected $value = [];
 
     /**
      * Sets container value.
      *
-     * @param array $value
+     * @param string[] $value
+     * @return void
      */
     public function setValue(array $value)
     {
@@ -43,7 +44,7 @@ public function getHTML($formName)
 		<h2 class="sectionTitle">{$this->getLabel()}</h2>
 		<p class="sectionDescription">{$this->getDescription()}</p>
 	</header>
-	
+
 	<dl class="wide">
 		{$content}
 	</dl>
diff --git a/wcfsetup/install/files/lib/system/form/container/SelectionFormElementContainer.class.php b/wcfsetup/install/files/lib/system/form/container/SelectionFormElementContainer.class.php
index d253942d319..69e14d3153c 100644
--- a/wcfsetup/install/files/lib/system/form/container/SelectionFormElementContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/container/SelectionFormElementContainer.class.php
@@ -23,6 +23,7 @@ abstract class SelectionFormElementContainer extends AbstractFormElementContaine
      * Sets container name.
      *
      * @param string $name
+     * @return void
      */
     public function setName($name)
     {
diff --git a/wcfsetup/install/files/lib/system/form/container/SingleSelectionFormElementContainer.class.php b/wcfsetup/install/files/lib/system/form/container/SingleSelectionFormElementContainer.class.php
index d96f7a77945..e76bc9650f1 100644
--- a/wcfsetup/install/files/lib/system/form/container/SingleSelectionFormElementContainer.class.php
+++ b/wcfsetup/install/files/lib/system/form/container/SingleSelectionFormElementContainer.class.php
@@ -23,6 +23,7 @@ class SingleSelectionFormElementContainer extends SelectionFormElementContainer
      * Sets container value.
      *
      * @param string $value
+     * @return void
      */
     public function setValue($value)
     {
@@ -53,7 +54,7 @@ public function getHTML($formName)
 		<h2 class="sectionTitle">{$this->getLabel()}</h2>
 		<p class="sectionDescription">{$this->getDescription()}</p>
 	</header>
-	
+
 	<dl>
 		<dd>{$content}</dd>
 	</dl>
diff --git a/wcfsetup/install/files/lib/system/form/element/AbstractNamedFormElement.class.php b/wcfsetup/install/files/lib/system/form/element/AbstractNamedFormElement.class.php
index 881e94fefd0..6778dbddfe8 100644
--- a/wcfsetup/install/files/lib/system/form/element/AbstractNamedFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/element/AbstractNamedFormElement.class.php
@@ -35,6 +35,7 @@ abstract class AbstractNamedFormElement extends AbstractFormElement
      * Sets element description.
      *
      * @param string $description
+     * @return void
      */
     public function setDescription($description)
     {
@@ -44,7 +45,7 @@ public function setDescription($description)
     /**
      * Returns element description.
      *
-     * @return  string
+     * @return string
      */
     public function getDescription()
     {
@@ -55,6 +56,7 @@ public function getDescription()
      * Sets element name.
      *
      * @param string $name
+     * @return void
      */
     public function setName($name)
     {
@@ -64,7 +66,7 @@ public function setName($name)
     /**
      * Returns element name
      *
-     * @return  string
+     * @return string
      */
     public function getName()
     {
@@ -75,6 +77,7 @@ public function getName()
      * Sets element value.
      *
      * @param string $value
+     * @return void
      */
     public function setValue($value)
     {
diff --git a/wcfsetup/install/files/lib/system/form/element/LabelFormElement.class.php b/wcfsetup/install/files/lib/system/form/element/LabelFormElement.class.php
index d791810bc52..1b3dc2c3e42 100644
--- a/wcfsetup/install/files/lib/system/form/element/LabelFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/element/LabelFormElement.class.php
@@ -23,6 +23,7 @@ class LabelFormElement extends AbstractFormElement
      * Sets element text.
      *
      * @param string $text
+     * @return void
      */
     public function setText($text)
     {
diff --git a/wcfsetup/install/files/lib/system/form/element/MultipleSelectionFormElement.class.php b/wcfsetup/install/files/lib/system/form/element/MultipleSelectionFormElement.class.php
index 3ee434cd1d3..fca93a5c77b 100644
--- a/wcfsetup/install/files/lib/system/form/element/MultipleSelectionFormElement.class.php
+++ b/wcfsetup/install/files/lib/system/form/element/MultipleSelectionFormElement.class.php
@@ -38,6 +38,7 @@ public function setValue($value)
      * Sets message displayed if input should be disabled.
      *
      * @param string $message
+     * @return void
      */
     public function setDisabledMessage($message)
     {
diff --git a/wcfsetup/install/files/lib/system/gridView/AbstractGridView.class.php b/wcfsetup/install/files/lib/system/gridView/AbstractGridView.class.php
index 580c54767d0..ca285d91a3d 100644
--- a/wcfsetup/install/files/lib/system/gridView/AbstractGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/AbstractGridView.class.php
@@ -23,6 +23,9 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 abstract class AbstractGridView
 {
@@ -37,18 +40,26 @@ abstract class AbstractGridView
     private array $quickInteractions = [];
 
     /**
-     * @var DatabaseObject[]
+     * @var TDatabaseObject[]
      */
     protected array $objects;
 
     protected int $objectCount;
+
+    /**
+     * @var TDatabaseObjectList
+     */
     protected DatabaseObjectList $objectList;
+
     private GridViewRowLink $rowLink;
     private int $rowsPerPage = 20;
     private string $baseUrl = '';
     private string $sortField = '';
     private string $sortOrder = 'ASC';
     private int $pageNo = 1;
+    /**
+     * @var array<string, string|int>
+     */
     private array $activeFilters = [];
     private string|int|null $objectIDFilter = null;
     private ?IInteractionProvider $interactionProvider = null;
@@ -111,6 +122,7 @@ public function addColumnAfter(GridViewColumn $column, string $afterID): void
 
     /**
      * Adds multiple new columns to the grid view.
+     *
      * @param GridViewColumn[] $columns
      */
     public function addColumns(array $columns): void
@@ -122,6 +134,7 @@ public function addColumns(array $columns): void
 
     /**
      * Returns all columns of the grid view.
+     *
      * @return GridViewColumn[]
      */
     public function getColumns(): array
@@ -131,6 +144,7 @@ public function getColumns(): array
 
     /**
      * Returns all visible (non-hidden) columns of the grid view.
+     *
      * @return GridViewColumn[]
      */
     public function getVisibleColumns(): array
@@ -154,6 +168,7 @@ public function getColumn(string $id): ?GridViewColumn
 
     /**
      * Returns all columns that are sortable.
+     *
      * @return GridViewColumn[]
      */
     public function getSortableColumns(): array
@@ -163,6 +178,7 @@ public function getSortableColumns(): array
 
     /**
      * Returns all columns that are filterable.
+     *
      * @return GridViewColumn[]
      */
     public function getFilterableColumns(): array
@@ -238,6 +254,7 @@ public function hasBulkInteractions(): bool
 
     /**
      * Returns the quick interactions.
+     *
      * @return IInteraction[]
      */
     public function getQuickInteractions(): array
@@ -265,6 +282,8 @@ public function renderRows(): string
 
     /**
      * Renders the given grid view column.
+     *
+     * @param TDatabaseObject $row
      */
     public function renderColumn(GridViewColumn $column, DatabaseObject $row): string
     {
@@ -340,6 +359,8 @@ public function renderBulkInteractionInitialization(): string
 
     /**
      * Renders the interactions for the given row.
+     *
+     * @param TDatabaseObject $row
      */
     public function renderInteractionContextMenuButton(DatabaseObject $row): string
     {
@@ -352,6 +373,8 @@ public function renderInteractionContextMenuButton(DatabaseObject $row): string
 
     /**
      * Renders the interactions for the given row.
+     *
+     * @param TDatabaseObject $row
      */
     public function renderQuickInteractions(DatabaseObject $row): string
     {
@@ -368,6 +391,8 @@ public function renderQuickInteractions(DatabaseObject $row): string
 
     /**
      * Returns the row data for the given identifier.
+     *
+     * @param TDatabaseObject $row
      */
     protected function getData(DatabaseObject $row, string $identifer): mixed
     {
@@ -517,6 +542,8 @@ public function getFilterActionEndpoint(): string
 
     /**
      * Sets the active filter values.
+     *
+     * @param array<string, string|int> $filters
      */
     public function setActiveFilters(array $filters): void
     {
@@ -525,6 +552,8 @@ public function setActiveFilters(array $filters): void
 
     /**
      * Returns the active filter values.
+     *
+     * @return array<string, string|int>
      */
     public function getActiveFilters(): array
     {
@@ -556,6 +585,8 @@ public function getFilterLabel(string $id): string
 
     /**
      * Gets the additional parameters of the grid view.
+     *
+     * @return mixed[]
      */
     public function getParameters(): array
     {
@@ -572,6 +603,8 @@ public function addRowLink(GridViewRowLink $rowLink): void
 
     /**
      * Returns the id for the given row.
+     *
+     * @param TDatabaseObject $row
      */
     public function getObjectID(DatabaseObject $row): string|int
     {
@@ -653,6 +686,8 @@ protected function prepareRenderers(): void
 
     /**
      * Returns the rows for the active page.
+     *
+     * @return TDatabaseObject[]
      */
     public function getRows(): array
     {
@@ -678,6 +713,8 @@ public function countRows(): int
 
     /**
      * Returns the database object list.
+     *
+     * @return TDatabaseObjectList
      */
     public function getObjectList(): DatabaseObjectList
     {
@@ -736,6 +773,8 @@ protected function applyFilters(): void
 
     /**
      * Creates the database object list of this grid view.
+     *
+     * @return TDatabaseObjectList
      */
     protected abstract function createObjectList(): DatabaseObjectList;
 }
diff --git a/wcfsetup/install/files/lib/system/gridView/GridViewColumn.class.php b/wcfsetup/install/files/lib/system/gridView/GridViewColumn.class.php
index 98a5d2d158e..794fd16c974 100644
--- a/wcfsetup/install/files/lib/system/gridView/GridViewColumn.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/GridViewColumn.class.php
@@ -17,15 +17,22 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @phpstan-type ColumnRenderer IColumnRenderer<DatabaseObject|\wcf\data\DatabaseObjectDecorator>
  */
 final class GridViewColumn
 {
     /**
-     * @var IColumnRenderer[]
+     * @var ColumnRenderer[]
      */
     private array $renderer = [];
     private string $label = '';
+
+    /**
+     * @var DefaultColumnRenderer<DatabaseObject>
+     */
     private static DefaultColumnRenderer $defaultRenderer;
+
     private bool $sortable = false;
     private string $sortByDatabaseColumn = '';
     private ?IGridViewFilter $filter = null;
@@ -86,6 +93,8 @@ static function (IColumnRenderer $renderer) {
 
     /**
      * Sets the renderer of this column.
+     *
+     * @param ColumnRenderer[]|ColumnRenderer $renderers
      */
     public function renderer(array|IColumnRenderer $renderers): static
     {
@@ -94,7 +103,6 @@ public function renderer(array|IColumnRenderer $renderers): static
         }
 
         foreach ($renderers as $renderer) {
-            \assert($renderer instanceof IColumnRenderer);
             $this->renderer[] = $renderer;
         }
 
@@ -124,7 +132,7 @@ public function sortable(bool $sortable = true, string $sortByDatabaseColumn = '
 
     /**
      * Returns the renderers of this column.
-     * @return IColumnRenderer[]
+     * @return IColumnRenderer<DatabaseObject>[]
      */
     public function getRenderers(): array
     {
@@ -260,6 +268,8 @@ public function applyRowLink(): bool
 
     /**
      * Returns the default renderer for the rendering of columns.
+     *
+     * @return DefaultColumnRenderer<DatabaseObject>
      */
     private static function getDefaultRenderer(): DefaultColumnRenderer
     {
diff --git a/wcfsetup/install/files/lib/system/gridView/GridViewRowLink.class.php b/wcfsetup/install/files/lib/system/gridView/GridViewRowLink.class.php
index 8c4ddeaf3c4..2342c0f08a4 100644
--- a/wcfsetup/install/files/lib/system/gridView/GridViewRowLink.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/GridViewRowLink.class.php
@@ -18,6 +18,9 @@
  */
 class GridViewRowLink
 {
+    /**
+     * @param array<string, mixed> $parameters
+     */
     public function __construct(
         private readonly string $controllerClass = '',
         private readonly array $parameters = [],
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionGridView.class.php
index 188b8b9de7a..ed604e9c091 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionGridView.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\gridView\admin;
 
+use wcf\data\acp\session\access\log\ACPSessionAccessLog;
 use wcf\data\acp\session\access\log\ACPSessionAccessLogList;
 use wcf\event\gridView\admin\ACPSessionGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
@@ -23,6 +24,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<ACPSessionAccessLog, ACPSessionAccessLogList>
  */
 final class ACPSessionGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionLogGridView.class.php
index cade75a544d..6ba3666718e 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/ACPSessionLogGridView.class.php
@@ -4,6 +4,7 @@
 
 use wcf\acp\form\UserEditForm;
 use wcf\acp\page\ACPSessionLogPage;
+use wcf\data\acp\session\log\ACPSessionLog;
 use wcf\data\acp\session\log\ACPSessionLogList;
 use wcf\event\gridView\admin\ACPSessionLogGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
@@ -28,6 +29,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<ACPSessionLog, ACPSessionLogList>
  */
 final class ACPSessionLogGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/ArticleGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/ArticleGridView.class.php
index ffe5655f16b..2e0fb341a3f 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/ArticleGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/ArticleGridView.class.php
@@ -31,7 +31,6 @@
 use wcf\system\interaction\Divider;
 use wcf\system\interaction\EditInteraction;
 use wcf\system\WCF;
-use wcf\util\DateUtil;
 use wcf\util\StringUtil;
 
 /**
@@ -41,6 +40,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Article, AccessibleArticleList>
  */
 final class ArticleGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/AttachmentGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/AttachmentGridView.class.php
index 907c3d0e75a..83bbe46d506 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/AttachmentGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/AttachmentGridView.class.php
@@ -37,6 +37,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<AdministrativeAttachment, AdministrativeAttachmentList>
  */
 final class AttachmentGridView extends AbstractGridView
 {
@@ -147,6 +149,9 @@ public function render(mixed $value, DatabaseObject $row): string
         $this->setSortField('uploadTime');
     }
 
+    /**
+     * @return array<string, string>
+     */
     private function getAvailableFileTypes(): array
     {
         $sql = "SELECT    DISTINCT file_table.mimeType
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/BBCodeGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/BBCodeGridView.class.php
index eb73342b255..d68b1b16c60 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/BBCodeGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/BBCodeGridView.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\gridView\admin;
 
 use wcf\acp\form\BBCodeEditForm;
+use wcf\data\bbcode\BBCode;
 use wcf\data\bbcode\BBCodeList;
 use wcf\data\DatabaseObject;
 use wcf\event\gridView\admin\BBCodeGridViewInitialized;
@@ -24,6 +25,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<BBCode, BBCodeList>
  */
 final class BBCodeGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/BBCodeMediaProviderGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/BBCodeMediaProviderGridView.class.php
index a85a022b014..915a14144c1 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/BBCodeMediaProviderGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/BBCodeMediaProviderGridView.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\gridView\admin;
 
 use wcf\acp\form\BBCodeMediaProviderEditForm;
+use wcf\data\bbcode\media\provider\BBCodeMediaProvider;
 use wcf\data\bbcode\media\provider\BBCodeMediaProviderList;
 use wcf\event\gridView\admin\BBCodeMediaProviderGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
@@ -25,6 +26,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<BBCodeMediaProvider, BBCodeMediaProviderList>
  */
 final class BBCodeMediaProviderGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/BoxGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/BoxGridView.class.php
index 9010dc3df28..4a50aaa4878 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/BoxGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/BoxGridView.class.php
@@ -28,6 +28,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Box, BoxList>
  */
 final class BoxGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/CaptchaQuestionGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/CaptchaQuestionGridView.class.php
index 5481f5b53e8..bcdd8254f25 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/CaptchaQuestionGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/CaptchaQuestionGridView.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\gridView\admin;
 
 use wcf\acp\form\CaptchaQuestionEditForm;
+use wcf\data\captcha\question\CaptchaQuestion;
 use wcf\data\captcha\question\I18nCaptchaQuestionList;
 use wcf\event\gridView\admin\CaptchaQuestionGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
@@ -25,6 +26,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<CaptchaQuestion, I18nCaptchaQuestionList>
  */
 final class CaptchaQuestionGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/CronjobGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/CronjobGridView.class.php
index bdab7921c99..5e79bd08150 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/CronjobGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/CronjobGridView.class.php
@@ -33,6 +33,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Cronjob, I18nCronjobList>
  */
 final class CronjobGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/CronjobLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/CronjobLogGridView.class.php
index 4fde553a57b..c64818197d5 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/CronjobLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/CronjobLogGridView.class.php
@@ -27,6 +27,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<CronjobLog, CronjobLogList>
  */
 final class CronjobLogGridView extends AbstractGridView
 {
@@ -46,6 +48,9 @@ public function __construct()
                 ->filter(new SelectFilter($availableCronjobs))
                 ->renderer([
                     new class($availableCronjobs) extends DefaultColumnRenderer {
+                        /**
+                         * @param array<int, string> $availableCronjobs
+                         */
                         public function __construct(private readonly array $availableCronjobs) {}
 
                         public function render(mixed $value, DatabaseObject $row): string
@@ -108,6 +113,9 @@ protected function getInitializedEvent(): CronjobLogGridViewInitialized
         return new CronjobLogGridViewInitialized($this);
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailableCronjobs(): array
     {
         $list = new I18nCronjobList();
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/EmailLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/EmailLogGridView.class.php
index 5b83eb99e0d..d817e2f6cc0 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/EmailLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/EmailLogGridView.class.php
@@ -31,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<EmailLogEntry, EmailLogEntryList>
  */
 final class EmailLogGridView extends AbstractGridView
 {
@@ -167,7 +169,7 @@ public function isAccessible(): bool
     }
 
     #[\Override]
-    protected function createObjectList(): DatabaseObjectList
+    protected function createObjectList(): EmailLogEntryList
     {
         $list = new EmailLogEntryList();
         $join = " LEFT JOIN wcf1_user user_table
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/ExceptionLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/ExceptionLogGridView.class.php
index 9fda4b9f0b5..e73e821a41d 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/ExceptionLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/ExceptionLogGridView.class.php
@@ -23,9 +23,14 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<DatabaseObject, DatabaseObjectList>
  */
 final class ExceptionLogGridView extends AbstractGridView
 {
+    /**
+     * @var array<string, string>
+     */
     private array $availableLogFiles;
 
     public function __construct(bool $applyDefaultFilter = false)
@@ -66,10 +71,13 @@ public function isAccessible(): bool
         return WCF::getSession()->getPermission('admin.management.canViewLog');
     }
 
+    /**
+     * @return array<string, DatabaseObject>
+     */
     protected function loadDataSource(): array
     {
-        if (!empty($this->getActiveFilters()['exceptionID'])) {
-            $exceptionID = $this->getActiveFilters()['exceptionID'];
+        $exceptionID = $this->getActiveFilters()['exceptionID'] ?? '';
+        if ($exceptionID !== '') {
             $contents = $logFile = '';
             foreach ($this->getAvailableLogFiles() as $logFile) {
                 $contents = \file_get_contents(WCF_DIR . $logFile);
@@ -104,8 +112,11 @@ protected function loadDataSource(): array
             }
 
             return $parsedExceptions;
-        } elseif (!empty($this->getActiveFilters()['logFile'])) {
-            $contents = \file_get_contents(WCF_DIR . $this->getActiveFilters()['logFile']);
+        }
+
+        $logFile = $this->getActiveFilters()['logFile'] ?? '';
+        if ($logFile !== '') {
+            $contents = \file_get_contents(WCF_DIR . $logFile);
             $exceptions = ExceptionLogUtil::splitLog($contents);
             $parsedExceptions = [];
 
@@ -126,6 +137,9 @@ protected function loadDataSource(): array
         return [];
     }
 
+    /**
+     * @param array{exceptionID: string, message: string, date: string, logFile: string} $data
+     */
     private function createObject(array $data): DatabaseObject
     {
         return new class(null, $data) extends DatabaseObject {
@@ -179,6 +193,9 @@ protected function applyFilters(): void
         // Overwrite the default filtering, as this is already applied when the data is loaded.
     }
 
+    /**
+     * @return array<string, string>
+     */
     private function getAvailableLogFiles(): array
     {
         if (!isset($this->availableLogFiles)) {
@@ -204,6 +221,9 @@ protected function getInitializedEvent(): ExceptionLogGridViewInitialized
         return new ExceptionLogGridViewInitialized($this);
     }
 
+    /**
+     * @return DatabaseObjectList<DatabaseObject>
+     */
     #[\Override]
     protected function createObjectList(): DatabaseObjectList
     {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/LabelGroupGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/LabelGroupGridView.class.php
index b225f3da9f2..d05d592ebe9 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/LabelGroupGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/LabelGroupGridView.class.php
@@ -4,6 +4,7 @@
 
 use wcf\acp\form\LabelGroupEditForm;
 use wcf\data\label\group\I18nLabelGroupList;
+use wcf\data\label\group\LabelGroup;
 use wcf\event\gridView\admin\LabelGroupGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\filter\I18nTextFilter;
@@ -26,6 +27,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<LabelGroup, I18nLabelGroupList>
  */
 final class LabelGroupGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/LanguageGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/LanguageGridView.class.php
index 1f6e0386739..b6ea1509a8f 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/LanguageGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/LanguageGridView.class.php
@@ -33,6 +33,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Language, LanguageList>
  */
 final class LanguageGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/LanguageItemGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/LanguageItemGridView.class.php
index 9f747e36435..727785ce0b9 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/LanguageItemGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/LanguageItemGridView.class.php
@@ -31,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<LanguageItem, LanguageItemList>
  */
 final class LanguageItemGridView extends AbstractGridView
 {
@@ -174,6 +176,9 @@ protected function getInitializedEvent(): LanguageItemGridViewInitialized
         return new LanguageItemGridViewInitialized($this);
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailableCategories(): array
     {
         $list = new LanguageCategoryList();
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/MenuGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/MenuGridView.class.php
index 4d027f1eadd..a9f83ed4430 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/MenuGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/MenuGridView.class.php
@@ -6,6 +6,7 @@
 use wcf\data\box\Box;
 use wcf\data\DatabaseObject;
 use wcf\data\menu\I18nMenuList;
+use wcf\data\menu\Menu;
 use wcf\event\gridView\admin\MenuGridViewInitialized;
 use wcf\system\gridView\AbstractGridView;
 use wcf\system\gridView\filter\I18nTextFilter;
@@ -30,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Menu, I18nMenuList>
  */
 final class MenuGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/ModificationLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/ModificationLogGridView.class.php
index 5e4e735ca30..33fae532f0a 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/ModificationLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/ModificationLogGridView.class.php
@@ -34,6 +34,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<ModificationLog, ModificationLogList>
  */
 final class ModificationLogGridView extends AbstractGridView
 {
@@ -78,6 +80,9 @@ public function render(mixed $value, DatabaseObject $row): string
                 ])
                 ->filter(
                     new class($this->getAvailableActions()) implements IGridViewFilter {
+                        /**
+                         * @param array<string|int, string> $options
+                         */
                         public function __construct(private readonly array $options) {}
 
                         #[\Override]
@@ -166,6 +171,9 @@ protected function createObjectList(): ModificationLogList
         return new ModificationLogList();
     }
 
+    /**
+     * @return IViewableModificationLog[]
+     */
     #[\Override]
     public function getRows(): array
     {
@@ -213,6 +221,9 @@ protected function getInitializedEvent(): ModificationLogGridViewInitialized
         return new ModificationLogGridViewInitialized($this);
     }
 
+    /**
+     * @return array<string, string>
+     */
     private function getAvailableActions(): array
     {
         $packages = $actions = $availableActions = [];
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/PackageUpdateServerGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/PackageUpdateServerGridView.class.php
index fc1c3a12344..b2ff3e45f43 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/PackageUpdateServerGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/PackageUpdateServerGridView.class.php
@@ -35,6 +35,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<PackageUpdateServer, PackageUpdateServerList>
  */
 final class PackageUpdateServerGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/PageGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/PageGridView.class.php
index 243a7830705..6c3b2da8c9d 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/PageGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/PageGridView.class.php
@@ -36,6 +36,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Page, PageList>
  */
 final class PageGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionGridView.class.php
index f50364ee9df..34fa477449c 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionGridView.class.php
@@ -31,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<PaidSubscription, I18nPaidSubscriptionList>
  */
 final class PaidSubscriptionGridView extends AbstractGridView
 {
@@ -122,6 +124,9 @@ public function render(mixed $value, DatabaseObject $row): string
         $this->addRowLink(new GridViewRowLink(PaidSubscriptionEditForm::class));
     }
 
+    /**
+     * @return string[]
+     */
     private function getAvailableCurrencies(): array
     {
         $availableCurrencies = [];
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionTransactionLogGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionTransactionLogGridView.class.php
index 22b48572d1d..afcab303ba4 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionTransactionLogGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionTransactionLogGridView.class.php
@@ -40,6 +40,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<PaidSubscriptionTransactionLog, PaidSubscriptionTransactionLogList>
  */
 final class PaidSubscriptionTransactionLogGridView extends AbstractGridView
 {
@@ -120,6 +122,9 @@ public function render(mixed $value, DatabaseObject $row): string
         $this->setSortOrder("DESC");
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailablePaymentMethods(): array
     {
         $paymentMethods = [];
@@ -130,6 +135,9 @@ private function getAvailablePaymentMethods(): array
         return $paymentMethods;
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailableSubscriptions(): array
     {
         $subscriptions = [];
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionUserGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionUserGridView.class.php
index cfd8918a3e0..0f10fc21a18 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionUserGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/PaidSubscriptionUserGridView.class.php
@@ -31,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<PaidSubscriptionUser, PaidSubscriptionUserList>
  */
 final class PaidSubscriptionUserGridView extends AbstractGridView
 {
@@ -74,6 +76,9 @@ public function __construct()
         $this->setSortField("userID");
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailableSubscriptions(): array
     {
         $subscriptions = [];
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/StyleGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/StyleGridView.class.php
index ba7ecfa7296..4a39f91e62f 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/StyleGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/StyleGridView.class.php
@@ -29,6 +29,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Style, StyleList>
  */
 final class StyleGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/TagGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/TagGridView.class.php
index aafacb49b8b..c3ce4c9beb6 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/TagGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/TagGridView.class.php
@@ -31,6 +31,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Tag, TagList>
  */
 final class TagGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/TemplateGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/TemplateGridView.class.php
index cdc0b1ec2a2..e782021ce5f 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/TemplateGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/TemplateGridView.class.php
@@ -37,6 +37,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<Template, TemplateList>
  */
 final class TemplateGridView extends AbstractGridView
 {
@@ -88,6 +90,9 @@ public function __construct(?int $templateGroupID = null)
         }
     }
 
+    /**
+     * @return array<string, Package>
+     */
     private function getApplications(): array
     {
         $applications = ApplicationHandler::getInstance()->getApplications();
@@ -146,6 +151,9 @@ public function renderValue(string $value): string
                 return $templateGroup->getTitle();
             }
 
+            /**
+             * @return list<array{depth: int, value: int, label: string}>
+             */
             private function getSelectOptions(): array
             {
                 $options = [
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/TemplateGroupGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/TemplateGroupGridView.class.php
index 69cc7a13b2a..25626ef89ec 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/TemplateGroupGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/TemplateGroupGridView.class.php
@@ -25,6 +25,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<TemplateGroup, I18nTemplateGroupList>
  */
 final class TemplateGroupGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/UserAuthenticationFailureGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/UserAuthenticationFailureGridView.class.php
index b71e4be3a6a..00b930e9d3e 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/UserAuthenticationFailureGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/UserAuthenticationFailureGridView.class.php
@@ -28,6 +28,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<UserAuthenticationFailure, UserAuthenticationFailureList>
  */
 final class UserAuthenticationFailureGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/UserGroupAssignmentGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/UserGroupAssignmentGridView.class.php
index 10f601b5504..35aad185f7f 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/UserGroupAssignmentGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/UserGroupAssignmentGridView.class.php
@@ -29,6 +29,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<UserGroupAssignment, UserGroupAssignmentList>
  */
 final class UserGroupAssignmentGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/UserGroupGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/UserGroupGridView.class.php
index 326552feebf..07cf3c51fcd 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/UserGroupGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/UserGroupGridView.class.php
@@ -30,6 +30,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<UserGroup, I18nUserGroupList>
  */
 final class UserGroupGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/UserOptionGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/UserOptionGridView.class.php
index 0333b11c31d..34f74330780 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/UserOptionGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/UserOptionGridView.class.php
@@ -28,6 +28,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<UserOption, UserOptionList>
  */
 final class UserOptionGridView extends AbstractGridView
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/admin/UserRankGridView.class.php b/wcfsetup/install/files/lib/system/gridView/admin/UserRankGridView.class.php
index ac7e68b161e..8bc801036f4 100644
--- a/wcfsetup/install/files/lib/system/gridView/admin/UserRankGridView.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/admin/UserRankGridView.class.php
@@ -30,6 +30,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractGridView<UserRank, I18nUserRankList>
  */
 final class UserRankGridView extends AbstractGridView
 {
@@ -136,6 +138,9 @@ protected function getInitializedEvent(): UserRankGridViewInitialized
         return new UserRankGridViewInitialized($this);
     }
 
+    /**
+     * @return array<int, string>
+     */
     private function getAvailableUserGroups(): array
     {
         $groups = [];
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/AbstractFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/AbstractFilter.class.php
index 417efd220a1..a2e13205719 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/AbstractFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/AbstractFilter.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\gridView\filter;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 
 /**
@@ -22,6 +23,9 @@ public function renderValue(string $value): string
         return $value;
     }
 
+    /**
+     * @param DatabaseObjectList<DatabaseObject> $list
+     */
     protected function getDatabaseColumnName(DatabaseObjectList $list, string $id): string
     {
         return ($this->databaseColumn ?: $list->getDatabaseTableAlias() . '.' . $id);
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/CategoryFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/CategoryFilter.class.php
index bd0b8e313a0..aafdd6fa510 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/CategoryFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/CategoryFilter.class.php
@@ -17,6 +17,9 @@
  */
 class CategoryFilter extends AbstractFilter
 {
+    /**
+     * @param \Traversable<mixed> $options
+     */
     public function __construct(private readonly \Traversable $options, string $databaseColumn = '')
     {
         parent::__construct($databaseColumn);
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/IGridViewFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/IGridViewFilter.class.php
index 7d9d5e4d9a0..dfbcb648956 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/IGridViewFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/IGridViewFilter.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\gridView\filter;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\system\form\builder\field\AbstractFormField;
 
@@ -22,6 +23,8 @@ public function getFormField(string $id, string $label): AbstractFormField;
 
     /**
      * Applies the filter to the given database object list.
+     *
+     * @param DatabaseObjectList<DatabaseObject> $list
      */
     public function applyFilter(DatabaseObjectList $list, string $id, string $value): void;
 
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/NumericFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/NumericFilter.class.php
index 14fb1976079..16704eac69e 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/NumericFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/NumericFilter.class.php
@@ -65,6 +65,9 @@ public function renderValue(string $value): string
         return '';
     }
 
+    /**
+     * @return array{from: int, to: int}
+     */
     private function parseValue(string $value): array
     {
         $from = 0;
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/SelectFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/SelectFilter.class.php
index ad017420c79..afc5877e611 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/SelectFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/SelectFilter.class.php
@@ -17,6 +17,9 @@
  */
 class SelectFilter extends AbstractFilter
 {
+    /**
+     * @param array<string|int, mixed> $options
+     */
     public function __construct(
         private readonly array $options,
         string $databaseColumn = '',
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/TimeFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/TimeFilter.class.php
index 7b30346bc0d..f1cf640bf4c 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/TimeFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/TimeFilter.class.php
@@ -99,6 +99,9 @@ public function renderValue(string $value): string
         return '';
     }
 
+    /**
+     * @return array{from: int, to: int}
+     */
     private function getTimestamps(string $value): array
     {
         $from = 0;
diff --git a/wcfsetup/install/files/lib/system/gridView/filter/UserFilter.class.php b/wcfsetup/install/files/lib/system/gridView/filter/UserFilter.class.php
index 849375e2a04..299e430a3f4 100644
--- a/wcfsetup/install/files/lib/system/gridView/filter/UserFilter.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/filter/UserFilter.class.php
@@ -36,7 +36,7 @@ public function applyFilter(DatabaseObjectList $list, string $id, string $value)
     #[\Override]
     public function renderValue(string $value): string
     {
-        $user = UserRuntimeCache::getInstance()->getObject($value);
+        $user = UserRuntimeCache::getInstance()->getObject((int)$value);
 
         return $user ? $user->username : '';
     }
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/AbstractColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/AbstractColumnRenderer.class.php
index 7a489fc6fff..287e29b3fba 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/AbstractColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/AbstractColumnRenderer.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\gridView\renderer;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 
 /**
  * Provides an abstract implementation of a column renderer.
@@ -11,6 +12,9 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @implements IColumnRenderer<TDatabaseObject>
  */
 abstract class AbstractColumnRenderer implements IColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/CategoryColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/CategoryColumnRenderer.class.php
index 18f7c891120..35c5ccc1cc5 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/CategoryColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/CategoryColumnRenderer.class.php
@@ -13,6 +13,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class CategoryColumnRenderer extends DefaultColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/CurrencyColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/CurrencyColumnRenderer.class.php
index c65b4c9908e..5167ae148c0 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/CurrencyColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/CurrencyColumnRenderer.class.php
@@ -13,6 +13,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class CurrencyColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/DefaultColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/DefaultColumnRenderer.class.php
index d60ac0354dc..0cb13c78415 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/DefaultColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/DefaultColumnRenderer.class.php
@@ -3,7 +3,7 @@
 namespace wcf\system\gridView\renderer;
 
 use wcf\data\DatabaseObject;
-use wcf\util\StringUtil;
+use wcf\data\DatabaseObjectDecorator;
 
 /**
  * The default column renderer is automatically applied to all columns if no other renderers have been set.
@@ -13,6 +13,9 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @extends AbstractColumnRenderer<TDatabaseObject>
  */
 class DefaultColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/EmailColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/EmailColumnRenderer.class.php
index 45ed036ed85..73b9842b783 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/EmailColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/EmailColumnRenderer.class.php
@@ -11,6 +11,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class EmailColumnRenderer extends AbstractColumnRenderer implements ILinkColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/FilesizeColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/FilesizeColumnRenderer.class.php
index 9e125402a16..b1433e9b988 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/FilesizeColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/FilesizeColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2025 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class FilesizeColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/IColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/IColumnRenderer.class.php
index c491ada6373..9e1da06a508 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/IColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/IColumnRenderer.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\gridView\renderer;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 
 /**
  * Represents a column renderer of a grid view.
@@ -11,11 +12,16 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template-covariant TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
  */
 interface IColumnRenderer
 {
     /**
      * Renders the content of a column with the given value.
+     *
+     * @template TRow of TDatabaseObject
+     * @param TRow $row
      */
     public function render(mixed $value, DatabaseObject $row): string;
 
@@ -26,6 +32,9 @@ public function getClasses(): string;
 
     /**
      * Is called after the grid view data has been loaded and allows additional data to be loaded or cached.
+     *
+     * @template TRow of TDatabaseObject
+     * @param TRow $row
      */
     public function prepare(mixed $value, DatabaseObject $row): void;
 }
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/IpAddressColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/IpAddressColumnRenderer.class.php
index 479f9f2400a..b5d3cc3de7b 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/IpAddressColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/IpAddressColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class IpAddressColumnRenderer extends DefaultColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/LinkColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/LinkColumnRenderer.class.php
index 128aa088aad..0c007e6ea35 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/LinkColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/LinkColumnRenderer.class.php
@@ -14,9 +14,14 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class LinkColumnRenderer extends DefaultColumnRenderer implements ILinkColumnRenderer
 {
+    /**
+     * @param array<string, mixed> $parameters
+     */
     public function __construct(
         private readonly string $controllerClass,
         private readonly array $parameters = [],
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/NumberColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/NumberColumnRenderer.class.php
index dcf38c51101..6093a8021d7 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/NumberColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/NumberColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class NumberColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/ObjectIdColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/ObjectIdColumnRenderer.class.php
index e824f5d11d2..eaf048a2991 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/ObjectIdColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/ObjectIdColumnRenderer.class.php
@@ -11,6 +11,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class ObjectIdColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/ObjectLinkColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/ObjectLinkColumnRenderer.class.php
index 9a9b09dba5b..bffd8957ebf 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/ObjectLinkColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/ObjectLinkColumnRenderer.class.php
@@ -4,6 +4,7 @@
 
 use BadMethodCallException;
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectDecorator;
 use wcf\data\ILinkableObject;
 use wcf\data\ITitledObject;
 use wcf\system\cache\runtime\AbstractRuntimeCache;
@@ -19,15 +20,25 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @template TDatabaseObject of DatabaseObject|DatabaseObjectDecorator
+ * @template TRuntimeCache of AbstractRuntimeCache
+ * @extends DefaultColumnRenderer<TDatabaseObject>
  */
 abstract class ObjectLinkColumnRenderer extends DefaultColumnRenderer implements ILinkColumnRenderer
 {
+    /**
+     * @param array<string, mixed> $parameters
+     */
     public function __construct(
         private readonly string $controllerClass = '',
         private readonly array $parameters = [],
         private readonly string $titleLanguageItem = ''
     ) {}
 
+    /**
+     * @return TRuntimeCache
+     */
     protected abstract function getRuntimeCache(): AbstractRuntimeCache;
 
     #[\Override]
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/PhraseColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/PhraseColumnRenderer.class.php
index 01cba411281..fce8d3f7668 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/PhraseColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/PhraseColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class PhraseColumnRenderer extends DefaultColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/TimeColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/TimeColumnRenderer.class.php
index b2d357701aa..d57660fc571 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/TimeColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/TimeColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends AbstractColumnRenderer<DatabaseObject>
  */
 class TimeColumnRenderer extends AbstractColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/TruncatedTextColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/TruncatedTextColumnRenderer.class.php
index f8f4d375595..a6de31ad82f 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/TruncatedTextColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/TruncatedTextColumnRenderer.class.php
@@ -12,6 +12,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class TruncatedTextColumnRenderer extends DefaultColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/UserColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/UserColumnRenderer.class.php
index d348ce4a04e..af92dec22f7 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/UserColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/UserColumnRenderer.class.php
@@ -13,6 +13,8 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends DefaultColumnRenderer<DatabaseObject>
  */
 class UserColumnRenderer extends DefaultColumnRenderer
 {
diff --git a/wcfsetup/install/files/lib/system/gridView/renderer/UserLinkColumnRenderer.class.php b/wcfsetup/install/files/lib/system/gridView/renderer/UserLinkColumnRenderer.class.php
index 45d18486049..ae16a3f60c2 100644
--- a/wcfsetup/install/files/lib/system/gridView/renderer/UserLinkColumnRenderer.class.php
+++ b/wcfsetup/install/files/lib/system/gridView/renderer/UserLinkColumnRenderer.class.php
@@ -3,7 +3,7 @@
 namespace wcf\system\gridView\renderer;
 
 use wcf\data\DatabaseObject;
-use wcf\system\cache\runtime\AbstractRuntimeCache;
+use wcf\data\user\User;
 use wcf\system\cache\runtime\UserRuntimeCache;
 use wcf\util\StringUtil;
 
@@ -14,9 +14,14 @@
  * @copyright   2001-2024 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
+ *
+ * @extends ObjectLinkColumnRenderer<User, UserRuntimeCache>
  */
 class UserLinkColumnRenderer extends ObjectLinkColumnRenderer
 {
+    /**
+     * @param array<string, mixed> $parameters
+     */
     public function __construct(
         string $controllerClass = '',
         array $parameters = [],
@@ -27,7 +32,7 @@ public function __construct(
     }
 
     #[\Override]
-    protected function getRuntimeCache(): AbstractRuntimeCache
+    protected function getRuntimeCache(): UserRuntimeCache
     {
         return UserRuntimeCache::getInstance();
     }
diff --git a/wcfsetup/install/files/lib/system/html/AbstractHtmlProcessor.class.php b/wcfsetup/install/files/lib/system/html/AbstractHtmlProcessor.class.php
index 69d96594ca3..a0beb19bc88 100644
--- a/wcfsetup/install/files/lib/system/html/AbstractHtmlProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/AbstractHtmlProcessor.class.php
@@ -12,12 +12,13 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       3.0
+ * @phpstan-type Context array{objectType: string, objectTypeID: int, objectID: int}
  */
 abstract class AbstractHtmlProcessor implements IHtmlProcessor
 {
     /**
      * message context data
-     * @var array
+     * @var Context
      */
     protected $context = [
         'objectType' => '',
@@ -30,7 +31,8 @@ abstract class AbstractHtmlProcessor implements IHtmlProcessor
      *
      * @param string $objectType object type identifier
      * @param int $objectID object id
-     * @throws      InvalidObjectTypeException
+     * @return void
+     * @throws InvalidObjectTypeException
      */
     public function setContext($objectType, $objectID)
     {
@@ -49,7 +51,7 @@ public function setContext($objectType, $objectID)
     /**
      * Returns the message context data.
      *
-     * @return      array           message context data
+     * @return Context message context data
      */
     public function getContext()
     {
diff --git a/wcfsetup/install/files/lib/system/html/IHtmlProcessor.class.php b/wcfsetup/install/files/lib/system/html/IHtmlProcessor.class.php
index b744d051a31..90ee9289c79 100644
--- a/wcfsetup/install/files/lib/system/html/IHtmlProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/IHtmlProcessor.class.php
@@ -15,7 +15,7 @@ interface IHtmlProcessor
     /**
      * Returns the parsed html.
      *
-     * @return      string          parsed html
+     * @return string parsed html
      */
     public function getHtml();
 }
diff --git a/wcfsetup/install/files/lib/system/html/input/HtmlInputProcessor.class.php b/wcfsetup/install/files/lib/system/html/input/HtmlInputProcessor.class.php
index ccd863ee376..eae47e95a3d 100644
--- a/wcfsetup/install/files/lib/system/html/input/HtmlInputProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/HtmlInputProcessor.class.php
@@ -21,7 +21,7 @@ class HtmlInputProcessor extends AbstractHtmlProcessor
 {
     /**
      * list of embedded content grouped by type
-     * @var array
+     * @var array<string, mixed[]>
      */
     protected $embeddedContent = [];
 
@@ -48,6 +48,7 @@ class HtmlInputProcessor extends AbstractHtmlProcessor
      * @param string $objectType object type identifier
      * @param int $objectID object id
      * @param bool $convertFromBBCode interpret input as bbcode
+     * @return void
      */
     public function process($html, $objectType, $objectID = 0, $convertFromBBCode = false)
     {
@@ -80,6 +81,7 @@ public function process($html, $objectType, $objectID = 0, $convertFromBBCode =
      * to deal with HTML that has not been filtered previously.
      *
      * @param string $html html string
+     * @return void
      */
     public function processIntermediate($html)
     {
@@ -93,7 +95,8 @@ public function processIntermediate($html)
      * @param string $html html string
      * @param string $objectType object type identifier
      * @param int $objectID object id
-     * @since       3.1
+     * @return void
+     * @since 3.1
      */
     public function reprocess($html, $objectType, $objectID)
     {
@@ -150,7 +153,8 @@ public function reprocess($html, $objectType, $objectID)
      * @param string $html html string
      * @param string $objectType object type identifier
      * @param int $objectID object id
-     * @throws      \UnexpectedValueException
+     * @return void
+     * @throws \UnexpectedValueException
      */
     public function processEmbeddedContent($html, $objectType, $objectID)
     {
@@ -168,7 +172,7 @@ public function processEmbeddedContent($html, $objectType, $objectID)
     /**
      * Checks the input html for disallowed bbcodes and returns any matches.
      *
-     * @return      string[]        list of matched disallowed bbcodes
+     * @return string[] list of matched disallowed bbcodes
      */
     public function validate()
     {
@@ -179,6 +183,7 @@ public function validate()
      * Enforces the maximum depth of nested quotes.
      *
      * @param int $depth
+     * @return void
      */
     public function enforceQuoteDepth($depth, bool $isFullQuote = false)
     {
@@ -188,7 +193,7 @@ public function enforceQuoteDepth($depth, bool $isFullQuote = false)
     /**
      * Returns the parsed HTML ready to store.
      *
-     * @return      string  parsed html
+     * @return string parsed html
      */
     public function getHtml()
     {
@@ -198,7 +203,7 @@ public function getHtml()
     /**
      * Returns the raw text content of current document.
      *
-     * @return      string          raw text content
+     * @return string raw text content
      */
     public function getTextContent()
     {
@@ -208,7 +213,7 @@ public function getTextContent()
     /**
      * Returns true if the message appears to be empty.
      *
-     * @return      bool         true if message appears to be empty
+     * @return bool true if message appears to be empty
      */
     public function appearsToBeEmpty()
     {
@@ -218,7 +223,7 @@ public function appearsToBeEmpty()
     /**
      * Returns the all embedded content data.
      *
-     * @return array
+     * @return array<string, mixed[]>
      */
     public function getEmbeddedContent()
     {
@@ -241,6 +246,7 @@ public function getHtmlInputNodeProcessor()
      * Sets the new object id.
      *
      * @param int $objectID object id
+     * @return void
      */
     public function setObjectID($objectID)
     {
@@ -249,6 +255,8 @@ public function setObjectID($objectID)
 
     /**
      * Resets internal states and discards references to objects.
+     *
+     * @return void
      */
     protected function reset()
     {
@@ -257,7 +265,7 @@ protected function reset()
     }
 
     /**
-     * @return  IHtmlInputFilter
+     * @return IHtmlInputFilter
      */
     protected function getHtmlInputFilter()
     {
@@ -272,7 +280,7 @@ protected function getHtmlInputFilter()
      * Converts bbcodes using newlines into valid HTML.
      *
      * @param string $html html string
-     * @return      string          parsed html string
+     * @return string parsed html string
      */
     protected function convertToHtml($html)
     {
diff --git a/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php b/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
index 73abc9f656b..3acd06d7660 100644
--- a/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/filter/MessageHtmlInputFilter.class.php
@@ -77,6 +77,7 @@ protected function getPurifier()
      * Sets required configuration data for HTML filter.
      *
      * @param \HTMLPurifier_Config $config HTMLPurifier configuration
+     * @return void
      */
     protected function setAttributeDefinitions(\HTMLPurifier_Config $config)
     {
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeFont.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeFont.class.php
index 1a4bfc4e417..f48cc271585 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeFont.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeFont.class.php
@@ -98,6 +98,11 @@ public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProc
         }
     }
 
+    /**
+     * @param string $property
+     * @param string $value
+     * @return void
+     */
     protected function convertToSpan(\DOMElement $element, $property, $value)
     {
         $span = $element->ownerDocument->createElement('span');
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
index cbde3910f34..593b0b1be42 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
@@ -98,6 +98,7 @@ public function getSmileyCount()
      *
      * @param \DOMElement $element
      * @param string $class
+     * @return void
      */
     protected function handleAttachment(\DOMElement $element, $class)
     {
@@ -255,6 +256,7 @@ private function handleMedium(\DOMElement $element): void
      * Replaces image element with smiley metacode element.
      *
      * @param \DOMElement $element
+     * @return void
      */
     protected function handleSmiley(\DOMElement $element)
     {
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeProcessor.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeProcessor.class.php
index c6007a68d14..ca19fcede65 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeProcessor.class.php
@@ -181,7 +181,7 @@ class HtmlInputNodeProcessor extends AbstractHtmlNodeProcessor
 
     /**
      * list of embedded content grouped by type
-     * @var array
+     * @var array<string, mixed[]>
      */
     protected $embeddedContent = [];
 
@@ -277,6 +277,7 @@ public function process()
      * Enforces the maximum depth of nested quotes.
      *
      * @param int $depth
+     * @return void
      */
     public function enforceQuoteDepth($depth, bool $isFullQuote = false)
     {
@@ -336,6 +337,8 @@ public function enforceQuoteDepth($depth, bool $isFullQuote = false)
     /**
      * Fixes malformed HTML with metacode markers and text being placed
      * outside of paragraphs.
+     *
+     * @return void
      */
     protected function fixDom()
     {
@@ -404,6 +407,8 @@ protected function fixDom()
      * It is still possible to work around this by inserting useless text formats such
      * as bold to circumvent this check. The point of this method is to remove unintentional
      * and/or potentially unwanted whitespace, not guarding against people being jerks.
+     *
+     * @return void
      */
     protected function trim()
     {
@@ -567,7 +572,7 @@ protected function trim()
     /**
      * Checks the input html for disallowed bbcodes and returns any matches.
      *
-     * @return      string[]        list of matched disallowed bbcodes
+     * @return string[] list of matched disallowed bbcodes
      */
     public function validate()
     {
@@ -630,7 +635,7 @@ function (IHtmlNode $nodeHandler) use (&$result) {
     /**
      * Returns the raw text content of current document.
      *
-     * @return      string          raw text content
+     * @return string raw text content
      */
     public function getTextContent()
     {
@@ -660,7 +665,7 @@ public function getTextContent()
     /**
      * Returns true if the message appears to be empty.
      *
-     * @return      bool         true if message appears to be empty
+     * @return bool true if message appears to be empty
      */
     public function appearsToBeEmpty()
     {
@@ -683,6 +688,8 @@ public function appearsToBeEmpty()
 
     /**
      * Processes embedded content.
+     *
+     * @return void
      */
     public function processEmbeddedContent()
     {
@@ -694,7 +701,7 @@ public function processEmbeddedContent()
     /**
      * Returns the embedded content grouped by type.
      *
-     * @return      array
+     * @return mixed[]
      */
     public function getEmbeddedContent()
     {
@@ -705,7 +712,8 @@ public function getEmbeddedContent()
      * Add embedded content for provided type.
      *
      * @param string $type type name
-     * @param array $data embedded content
+     * @param mixed[] $data embedded content
+     * @return void
      */
     public function addEmbeddedContent($type, array $data)
     {
@@ -718,6 +726,8 @@ public function addEmbeddedContent($type, array $data)
 
     /**
      * Parses embedded content contained in metacode elements.
+     *
+     * @return void
      */
     protected function parseEmbeddedContent()
     {
@@ -764,6 +774,7 @@ public function createMetacodeElement(\DOMNode $node, $name, array $attributes)
      * those that are the only content in their line, are offered separately.
      *
      * @since 5.2
+     * @return void
      */
     protected function convertPlainLinks()
     {
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
index 3d5362cb937..bb82a747c42 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
@@ -28,7 +28,7 @@ class HtmlInputNodeTextParser
 {
     /**
      * list of markers per element that will face a replacement
-     * @var \DOMElement[][]
+     * @var array<int, array<string, \DOMElement>>
      */
     protected $elementStack = [];
 
@@ -39,7 +39,7 @@ class HtmlInputNodeTextParser
 
     /**
      * list of text nodes that will face a replacement
-     * @var \DOMText[]
+     * @var array<int, \DOMText>
      */
     protected $nodeStack = [];
 
@@ -50,7 +50,7 @@ class HtmlInputNodeTextParser
     protected $smileyCount = 0;
 
     /**
-     * @var string[]
+     * @var list<string>
      */
     protected $sourceBBCodes = [];
 
@@ -62,7 +62,7 @@ class HtmlInputNodeTextParser
 
     /**
      * list of smilies by smiley code
-     * @var Smiley[]
+     * @var array<string, Smiley>
      */
     protected static $smilies;
 
@@ -85,9 +85,6 @@ class HtmlInputNodeTextParser
 	~x";
 
     /**
-     * HtmlInputNodeTextParser constructor.
-     *
-     * @param HtmlInputNodeProcessor $htmlInputNodeProcessor
      * @param int $smileyCount
      */
     public function __construct(HtmlInputNodeProcessor $htmlInputNodeProcessor, $smileyCount = 0)
@@ -141,6 +138,8 @@ public function __construct(HtmlInputNodeProcessor $htmlInputNodeProcessor, $smi
 
     /**
      * Parses all text nodes searching for possible replacements.
+     *
+     * @return void
      */
     public function parse()
     {
@@ -234,6 +233,7 @@ public function parse()
      * @param \DOMText $text text node
      * @param string $value node value
      * @param string[] $usernames list of already found usernames
+     * @return void
      */
     protected function detectMention(\DOMText $text, string $value, array &$usernames)
     {
@@ -640,6 +640,7 @@ protected function parseSmiley(\DOMText $text, string $value)
      *
      * @param \DOMText $text text node
      * @param \DOMElement[] $elements elements to be inserted
+     * @return void
      */
     protected function replaceMatches(\DOMText $text, array $elements)
     {
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabMetacodeMarker.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabMetacodeMarker.class.php
index 5d8bc00baae..6f775032b99 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabMetacodeMarker.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeWoltlabMetacodeMarker.class.php
@@ -18,6 +18,31 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ * @phpstan-type MetacodePair array{
+ *  attributes: string,
+ *  close: ?\DOMElement,
+ *  closeSource?: string,
+ *  name: string,
+ *  open: ?\DOMElement,
+ *  openSource?: string,
+ *  useText?: bool|int,
+ * }
+ * @phpstan-type MetacodeGroup array{
+ *  attributes: string,
+ *  close: ?\DOMElement,
+ *  closeSource?: string,
+ *  open: ?\DOMElement,
+ *  openSource?: string,
+ *  useText?: bool|int,
+ * }
+ * @phpstan-type ParsedMetacodeGroup array{
+ *  attributes: list<string>,
+ *  close: ?\DOMElement,
+ *  closeSource?: string,
+ *  open: ?\DOMElement,
+ *  openSource?: string,
+ *  useText?: bool|int,
+ * }
  */
 class HtmlInputNodeWoltlabMetacodeMarker extends AbstractHtmlInputNode
 {
@@ -94,9 +119,9 @@ public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProc
     /**
      * Filters groups by reverting metacode markers for invalid bbcodes.
      *
-     * @param array $groups grouped list of bbcode marker pairs
+     * @param array<string, list<MetacodeGroup>> $groups grouped list of bbcode marker pairs
      * @param AbstractHtmlNodeProcessor $htmlNodeProcessor node processor instance
-     * @return      array                           filtered groups
+     * @return array<string, list<MetacodeGroup>> filtered groups
      */
     protected function filterGroups(array $groups, AbstractHtmlNodeProcessor $htmlNodeProcessor)
     {
@@ -127,9 +152,9 @@ protected function filterGroups(array $groups, AbstractHtmlNodeProcessor $htmlNo
     /**
      * Transforms bbcode markers inside source code elements into their plain bbcode representation.
      *
-     * @param array $groups grouped list of bbcode marker pairs
+     * @param array<string, list<MetacodeGroup>> $groups grouped list of bbcode marker pairs
      * @param AbstractHtmlNodeProcessor $htmlNodeProcessor node processor instance
-     * @return      array                           filtered groups without source bbcodes
+     * @return array<string, list<MetacodeGroup>> filtered groups without source bbcodes
      */
     protected function revertMarkerInsideCodeBlocks(array $groups, AbstractHtmlNodeProcessor $htmlNodeProcessor)
     {
@@ -163,7 +188,7 @@ protected function revertMarkerInsideCodeBlocks(array $groups, AbstractHtmlNodeP
      * Returns `true` if the given element is inside a code element.
      *
      * @param \DOMElement $element
-     * @return  bool
+     * @return bool
      */
     protected function isInsideCode(\DOMElement $element)
     {
@@ -197,7 +222,7 @@ protected function isInsideCode(\DOMElement $element)
      * Builds the list of paired bbcode markers.
      *
      * @param \DOMElement[] $elements list of marker elements
-     * @return  array       list of paired bbcode markers
+     * @return array<string, MetacodePair> list of paired bbcode markers
      */
     protected function buildPairs(array $elements)
     {
@@ -236,8 +261,8 @@ protected function buildPairs(array $elements)
     /**
      * Validates bbcode marker pairs to include both an opening and closing element.
      *
-     * @param array $pairs list of paired bbcode markers
-     * @return  array       filtered list of paired bbcode markers
+     * @param array<string, MetacodePair> $pairs list of paired bbcode markers
+     * @return array<string, MetacodePair> filtered list of paired bbcode markers
      */
     protected function validatePairs(array $pairs)
     {
@@ -259,8 +284,8 @@ protected function validatePairs(array $pairs)
     /**
      * Groups bbcode marker pairs by their common bbcode identifier.
      *
-     * @param array $pairs list of paired bbcode markers
-     * @return  array       grouped list of bbcode marker pairs
+     * @param array<string, MetacodePair> $pairs list of paired bbcode markers
+     * @return array<string, list<MetacodeGroup>> grouped list of bbcode marker pairs
      */
     protected function groupPairsByName(array $pairs)
     {
@@ -288,8 +313,8 @@ protected function groupPairsByName(array $pairs)
     /**
      * Converts source bbcode groups.
      *
-     * @param array $groups grouped list of bbcode marker pairs
-     * @return      array           filtered groups without source bbcodes
+     * @param array<string, list<MetacodeGroup>> $groups grouped list of bbcode marker pairs
+     * @return array<string, list<MetacodeGroup>> filtered groups without source bbcodes
      */
     protected function convertSourceGroups(array $groups)
     {
@@ -326,7 +351,8 @@ protected function convertSourceGroups(array $groups)
     /**
      * Converts bbcode marker pairs into block- or inline-elements.
      *
-     * @param array $groups grouped list of bbcode marker pairs
+     * @param array<string, list<MetacodeGroup>> $groups grouped list of bbcode marker pairs
+     * @return void
      */
     protected function convertGroups(array $groups)
     {
@@ -357,6 +383,7 @@ protected function convertGroups(array $groups)
      * @param \DOMElement $start start node
      * @param \DOMElement $end end node
      * @param string $attributes encoded attribute string
+     * @return void
      */
     protected function convertBlockElement($name, $start, $end, $attributes)
     {
@@ -430,6 +457,7 @@ protected function convertBlockElement($name, $start, $end, $attributes)
      * @param \DOMElement $start start node
      * @param \DOMElement $end end node
      * @param string $attributes encoded attribute string
+     * @return void
      */
     protected function convertInlineElement($name, $start, $end, $attributes)
     {
@@ -526,9 +554,9 @@ protected function convertInlineElement($name, $start, $end, $attributes)
      *
      * @param string $name element tag name
      * @param string $attributes encoded attribute string
-     * @param \DOMElement|null $startNode first node to wrap
-     * @param \DOMElement|null $endNode last node to wrap
-     * @return  \DOMElement     newly created element
+     * @param ?\DOMElement $startNode first node to wrap
+     * @param ?\DOMElement $endNode last node to wrap
+     * @return \DOMElement newly created element
      */
     protected function wrapContent($name, $attributes, $startNode, $endNode)
     {
@@ -572,7 +600,7 @@ protected function wrapContent($name, $attributes, $startNode, $endNode)
      * Returns true if provided node is a block element.
      *
      * @param \DOMNode $node node
-     * @return  bool        true for certain block elements
+     * @return bool true for certain block elements
      */
     protected function isBlockElement(\DOMNode $node)
     {
@@ -601,7 +629,8 @@ protected function isBlockElement(\DOMNode $node)
      * to convert markers inside source code elements.
      *
      * @param string $name bbcode name
-     * @param array $pair bbcode marker pair
+     * @param ParsedMetacodeGroup $pair bbcode marker pair
+     * @return void
      */
     protected function convertToBBCode($name, array $pair)
     {
@@ -610,7 +639,7 @@ protected function convertToBBCode($name, array $pair)
         /** @var \DOMElement $end */
         $end = $pair['close'];
 
-        $attributes = $pair['attributes'] ?? [];
+        $attributes = $pair['attributes'];
         $content = '';
         if (isset($pair['useText']) && $pair['useText'] !== false && isset($attributes[$pair['useText']])) {
             $content = \array_splice($attributes, $pair['useText'])[0];
diff --git a/wcfsetup/install/files/lib/system/html/metacode/converter/IMetacodeConverter.class.php b/wcfsetup/install/files/lib/system/html/metacode/converter/IMetacodeConverter.class.php
index 945c1283d5b..7d245a34d52 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/converter/IMetacodeConverter.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/converter/IMetacodeConverter.class.php
@@ -20,16 +20,16 @@ interface IMetacodeConverter
      * The fragment must be inserted into your returned DOM element.
      *
      * @param \DOMDocumentFragment $fragment fragment containing all child nodes, must be appended to returned element
-     * @param array $attributes list of attributes
-     * @return  \DOMElement     new DOM element
+     * @param list<string> $attributes list of attributes
+     * @return \DOMElement new DOM element
      */
     public function convert(\DOMDocumentFragment $fragment, array $attributes);
 
     /**
      * Validates attributes before any DOM modification occurs.
      *
-     * @param array $attributes list of attributes
-     * @return  bool        false if attributes did not match the converter's expectation
+     * @param list<string> $attributes list of attributes
+     * @return bool false if attributes did not match the converter's expectation
      */
     public function validateAttributes(array $attributes);
 }
diff --git a/wcfsetup/install/files/lib/system/html/metacode/converter/SizeMetacodeConverter.class.php b/wcfsetup/install/files/lib/system/html/metacode/converter/SizeMetacodeConverter.class.php
index 6013e47d70b..8cf5fcd2864 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/converter/SizeMetacodeConverter.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/converter/SizeMetacodeConverter.class.php
@@ -12,6 +12,9 @@
  */
 class SizeMetacodeConverter extends AbstractMetacodeConverter
 {
+    /**
+     * @var int[]
+     */
     protected $sizes = [8, 10, 12, 14, 18, 24, 36];
 
     /**
diff --git a/wcfsetup/install/files/lib/system/html/metacode/converter/TableMetacodeConverter.class.php b/wcfsetup/install/files/lib/system/html/metacode/converter/TableMetacodeConverter.class.php
index 1de0c2cb714..b27b8b8db2d 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/converter/TableMetacodeConverter.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/converter/TableMetacodeConverter.class.php
@@ -69,6 +69,7 @@ public function convert(\DOMDocumentFragment $fragment, array $attributes)
      * Processes the rows of the table.
      *
      * @param \DOMElement $row
+     * @return void
      */
     protected function handleRow(\DOMElement $row)
     {
diff --git a/wcfsetup/install/files/lib/system/html/metacode/upcast/AttachMetacodeUpcast.class.php b/wcfsetup/install/files/lib/system/html/metacode/upcast/AttachMetacodeUpcast.class.php
index 2eb7b9f498d..a942a730086 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/upcast/AttachMetacodeUpcast.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/upcast/AttachMetacodeUpcast.class.php
@@ -86,7 +86,7 @@ public function hasValidAttributes(array $attributes): bool
         if (\count($attributes) < 1 || \count($attributes) > 3) {
             return false;
         }
-        $attachment = AttachmentRuntimeCache::getInstance()->getObject($attributes[0]);
+        $attachment = AttachmentRuntimeCache::getInstance()->getObject((int)$attributes[0]);
         if ($attachment === null) {
             return false;
         }
diff --git a/wcfsetup/install/files/lib/system/html/metacode/upcast/IMetacodeUpcast.class.php b/wcfsetup/install/files/lib/system/html/metacode/upcast/IMetacodeUpcast.class.php
index d48ba5d0f4f..d087ade97f1 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/upcast/IMetacodeUpcast.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/upcast/IMetacodeUpcast.class.php
@@ -16,7 +16,7 @@ interface IMetacodeUpcast
      * Converts a known metacode into the HTML representation for use by CKEditor5.
      *
      * @param \DOMElement $element
-     * @param array $attributes list of attributes
+     * @param list<string> $attributes list of attributes
      */
     public function upcast(\DOMElement $element, array $attributes): void;
 
@@ -24,7 +24,7 @@ public function upcast(\DOMElement $element, array $attributes): void;
      * Returns true if the given attributes are valid for this upcast.
      * If not, the metacode is converted to a text node with the bbcode output.
      *
-     * @param array $attributes
+     * @param list<string> $attributes
      * @return bool
      */
     public function hasValidAttributes(array $attributes): bool;
@@ -32,7 +32,7 @@ public function hasValidAttributes(array $attributes): bool;
     /**
      * Caches the object for the given attributes.
      *
-     * @param array $attributes
+     * @param list<string> $attributes
      */
     public function cacheObject(array $attributes): void;
 }
diff --git a/wcfsetup/install/files/lib/system/html/metacode/upcast/WsmMetacodeUpcast.class.php b/wcfsetup/install/files/lib/system/html/metacode/upcast/WsmMetacodeUpcast.class.php
index 0f46831745b..b2349722172 100644
--- a/wcfsetup/install/files/lib/system/html/metacode/upcast/WsmMetacodeUpcast.class.php
+++ b/wcfsetup/install/files/lib/system/html/metacode/upcast/WsmMetacodeUpcast.class.php
@@ -61,7 +61,7 @@ public function hasValidAttributes(array $attributes): bool
         if (\count($attributes) < 1 || \count($attributes) > 4) {
             return false;
         }
-        $media = MediaRuntimeCache::getInstance()->getObject($attributes[0]);
+        $media = MediaRuntimeCache::getInstance()->getObject((int)$attributes[0]);
         if ($media === null) {
             return false;
         }
diff --git a/wcfsetup/install/files/lib/system/html/node/AbstractHtmlNodeProcessor.class.php b/wcfsetup/install/files/lib/system/html/node/AbstractHtmlNodeProcessor.class.php
index d550daef57a..6ec55b5a3f9 100644
--- a/wcfsetup/install/files/lib/system/html/node/AbstractHtmlNodeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/node/AbstractHtmlNodeProcessor.class.php
@@ -36,7 +36,7 @@ abstract class AbstractHtmlNodeProcessor implements IHtmlNodeProcessor
 
     /**
      * storage for node replacements
-     * @var array
+     * @var list<array{data: array<string, mixed>, identifier: string, object: IHtmlNode}>
      */
     protected $nodeData = [];
 
@@ -121,6 +121,7 @@ static function ($matches) use ($data) {
                     $obj = $data['object'];
                     $string = $obj->replaceTag($data['data']);
 
+                    // @phpstan-ignore function.alreadyNarrowedType, function.alreadyNarrowedType, booleanAnd.alwaysFalse
                     if (!\is_string($string) && !\is_numeric($string)) {
                         throw new \RuntimeException(
                             \sprintf(
@@ -167,7 +168,7 @@ public function getDocument()
     /**
      * Returns a XPath instance for the current DOM document.
      *
-     * @return      \DOMXPath       XPath instance
+     * @return \DOMXPath XPath instance
      */
     public function getXPath()
     {
@@ -185,7 +186,7 @@ public function getXPath()
      * @param \DOMElement $element old element
      * @param string $tagName tag name for the new element
      * @param bool $preserveAttributes retain attributes for the new element
-     * @return      \DOMElement     newly created element
+     * @return \DOMElement newly created element
      */
     public function renameTag(\DOMElement $element, $tagName, $preserveAttributes = false)
     {
@@ -213,6 +214,7 @@ public function renameTag(\DOMElement $element, $tagName, $preserveAttributes =
      * @param \DOMElement $element target element
      * @param string $text text used to replace target
      * @param bool $isBlockElement true if element is a block element
+     * @return void
      */
     public function replaceElementWithText(\DOMElement $element, $text, $isBlockElement)
     {
@@ -234,6 +236,7 @@ public function replaceElementWithText(\DOMElement $element, $text, $isBlockElem
      * its original position.
      *
      * @param \DOMElement $element element to be removed
+     * @return void
      */
     public function unwrapContent(\DOMElement $element)
     {
@@ -249,7 +252,8 @@ public function unwrapContent(\DOMElement $element)
      *
      * @param IHtmlNode $htmlNode node processor instance
      * @param string $nodeIdentifier replacement node identifier
-     * @param array $data replacement data
+     * @param array<string, mixed> $data replacement data
+     * @return void
      */
     public function addNodeData(IHtmlNode $htmlNode, $nodeIdentifier, array $data)
     {
@@ -264,7 +268,7 @@ public function addNodeData(IHtmlNode $htmlNode, $nodeIdentifier, array $data)
      * Parses an attribute string.
      *
      * @param string $attributes base64 and JSON encoded attributes
-     * @return      array           parsed attributes
+     * @return array<string|int, string|int|bool|null> parsed attributes
      */
     public function parseAttributes($attributes)
     {
@@ -297,6 +301,7 @@ public function getHtmlProcessor()
      * Invokes a html node processor.
      *
      * @param IHtmlNode $htmlNode html node processor
+     * @return void
      */
     protected function invokeHtmlNode(IHtmlNode $htmlNode)
     {
@@ -328,6 +333,7 @@ protected function invokeHtmlNode(IHtmlNode $htmlNode)
      * @param string $classNamePattern full namespace pattern for class guessing
      * @param string[] $skipTags list of tag names that should be ignored
      * @param callable $callback optional callback
+     * @return void
      */
     protected function invokeNodeHandlers($classNamePattern, array $skipTags = [], ?callable $callback = null)
     {
diff --git a/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php b/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
index 8b16f766e1d..484834d9e92 100644
--- a/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
+++ b/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\html\node;
 
+use RuntimeException;
 use wcf\data\bbcode\BBCode;
 use wcf\data\ITitledObject;
 use wcf\system\Regex;
@@ -140,6 +141,7 @@ public function getObjectID()
      * Replaces the text content of the link with the object's title.
      *
      * @param ITitledObject $object
+     * @return void
      */
     public function setTitle(ITitledObject $object)
     {
@@ -154,7 +156,8 @@ public function setTitle(ITitledObject $object)
      * available for standalone links only.
      *
      * @param BBCode $bbcode
-     * @param int|null $overrideObjectID
+     * @param ?int $overrideObjectID
+     * @return void
      */
     public function replaceWithBBCode(BBCode $bbcode, $overrideObjectID = null)
     {
@@ -193,6 +196,9 @@ public function replaceWithBBCode(BBCode $bbcode, $overrideObjectID = null)
         DOMUtil::replaceElement($this->link, $metacodeElement, false);
     }
 
+    /**
+     * @return void
+     */
     protected function markAsTainted()
     {
         if (!$this->pristine) {
@@ -242,6 +248,7 @@ public static function splitAtLink(\DOMElement $link, ?\DOMElement $topLevelPare
 
         if ($next !== null) {
             $ancestor = $topLevelParent->parentNode;
+            \assert($parent instanceof \DOMNode);
             \assert($ancestor instanceof \DOMElement);
             $replaceNode = DOMUtil::splitParentsUntil(
                 $parent,
@@ -251,6 +258,7 @@ public static function splitAtLink(\DOMElement $link, ?\DOMElement $topLevelPare
         }
         if ($previous !== null) {
             $ancestor = $topLevelParent->parentNode;
+            \assert($parent instanceof \DOMNode);
             \assert($ancestor instanceof \DOMElement);
             $replaceNode = DOMUtil::splitParentsUntil(
                 $parent,
diff --git a/wcfsetup/install/files/lib/system/html/node/IHtmlNode.class.php b/wcfsetup/install/files/lib/system/html/node/IHtmlNode.class.php
index 6e7d75e3987..5d2818edae2 100644
--- a/wcfsetup/install/files/lib/system/html/node/IHtmlNode.class.php
+++ b/wcfsetup/install/files/lib/system/html/node/IHtmlNode.class.php
@@ -15,7 +15,7 @@ interface IHtmlNode
     /**
      * Returns the tag name of elements consumed by this node.
      *
-     * @return      string          tag name of consumed elements
+     * @return string tag name of consumed elements
      */
     public function getTagName();
 
@@ -23,7 +23,7 @@ public function getTagName();
      * Checks for disallowed bbcodes, must return the offending bbcode on match.
      *
      * @param AbstractHtmlNodeProcessor $htmlNodeProcessor node processor instance
-     * @return      string[]                        disallowed bbcodes on match or empty array
+     * @return string[] disallowed bbcodes on match or empty array
      */
     public function isAllowed(AbstractHtmlNodeProcessor $htmlNodeProcessor);
 
@@ -32,13 +32,15 @@ public function isAllowed(AbstractHtmlNodeProcessor $htmlNodeProcessor);
      *
      * @param \DOMElement[] $elements static list of matched elements, does not change when removing elements
      * @param AbstractHtmlNodeProcessor $htmlNodeProcessor node processor instance
+     * @return void
      */
     public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProcessor);
 
     /**
      * Replaces a placeholder tag with the provided data.
      *
-     * @param array $data replacement data
+     * @param array<string, mixed> $data replacement data
+     * @return string
      */
     public function replaceTag(array $data);
 }
diff --git a/wcfsetup/install/files/lib/system/html/node/IHtmlNodeProcessor.class.php b/wcfsetup/install/files/lib/system/html/node/IHtmlNodeProcessor.class.php
index 7a150de7c81..e789f474975 100644
--- a/wcfsetup/install/files/lib/system/html/node/IHtmlNodeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/node/IHtmlNodeProcessor.class.php
@@ -17,21 +17,21 @@ interface IHtmlNodeProcessor
     /**
      * Returns the currently loaded DOM document.
      *
-     * @return      \DOMDocument    active DOM document
+     * @return \DOMDocument active DOM document
      */
     public function getDocument();
 
     /**
      * Returns the final HTML for storage or display.
      *
-     * @return      string  parsed HTML
+     * @return string parsed HTML
      */
     public function getHtml();
 
     /**
      * Returns the html processor instance.
      *
-     * @return      IHtmlProcessor          html processor instance
+     * @return IHtmlProcessor html processor instance
      */
     public function getHtmlProcessor();
 
@@ -40,11 +40,14 @@ public function getHtmlProcessor();
      *
      * @param IHtmlProcessor $htmlProcessor html processor
      * @param string $html HTML string
+     * @return void
      */
     public function load(IHtmlProcessor $htmlProcessor, $html);
 
     /**
      * Processes the HTML and transforms it depending on the output type.
+     *
+     * @return void
      */
     public function process();
 }
diff --git a/wcfsetup/install/files/lib/system/html/output/HtmlOutputProcessor.class.php b/wcfsetup/install/files/lib/system/html/output/HtmlOutputProcessor.class.php
index 1ae88a7b807..fd2820aa167 100644
--- a/wcfsetup/install/files/lib/system/html/output/HtmlOutputProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/HtmlOutputProcessor.class.php
@@ -20,7 +20,7 @@ class HtmlOutputProcessor extends AbstractHtmlProcessor
     /**
      * Generate the table of contents, implicitly enable this for certain object types on demand.
      * @var bool|null
-     * @since   5.2
+     * @since 5.2
      */
     public $enableToc;
 
@@ -56,6 +56,7 @@ class HtmlOutputProcessor extends AbstractHtmlProcessor
      * @param int $objectID object id
      * @param bool $doKeywordHighlighting enable keyword highlighting
      * @param int $languageID content language id
+     * @return void
      */
     public function process($html, $objectType, $objectID, $doKeywordHighlighting = true, $languageID = null)
     {
@@ -78,7 +79,8 @@ public function process($html, $objectType, $objectID, $doKeywordHighlighting =
      * Sets the desired output type.
      *
      * @param string $outputType desired output type
-     * @throws      \InvalidArgumentException
+     * @return void
+     * @throws \InvalidArgumentException
      */
     public function setOutputType($outputType)
     {
@@ -125,7 +127,7 @@ public function setContext($objectType, $objectID)
     /**
      * Returns the output node processor instance.
      *
-     * @return      HtmlOutputNodeProcessor         output node processor instance
+     * @return HtmlOutputNodeProcessor output node processor instance
      */
     protected function getHtmlOutputNodeProcessor()
     {
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeA.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeA.class.php
index 47eaf3d6edd..5941d7ef8ca 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeA.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeA.class.php
@@ -206,6 +206,7 @@ private function isSuspiciousValue(string $value, UriInterface $href): bool
      *
      * @param \DOMElement $element
      * @param bool $isUgc
+     * @return void
      */
     public static function markLinkAsExternal(\DOMElement $element, $isUgc = false)
     {
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeImg.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeImg.class.php
index f417d57e3d2..52a6d4a9649 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeImg.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeImg.class.php
@@ -159,6 +159,7 @@ public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProc
      * @param \DOMElement $element
      * @param string $src
      * @param bool $isUgc
+     * @return void
      */
     protected function replaceExternalSource(\DOMElement $element, $src, $isUgc = false)
     {
@@ -186,6 +187,8 @@ protected function replaceExternalSource(\DOMElement $element, $src, $isUgc = fa
     }
 
     /**
+     * @param string[] $hostnames
+     * @return callable(string):bool
      * @deprecated 5.4 Use Url::getHostnameMatcher().
      */
     protected function getHostMatcher(array $hostnames)
@@ -198,7 +201,7 @@ protected function getHostMatcher(array $hostnames)
      * and whitelisted ones with wildcard support.
      *
      * @param string $hostname
-     * @return      bool
+     * @return bool
      */
     protected function bypassProxy($hostname)
     {
@@ -218,8 +221,8 @@ protected function bypassProxy($hostname)
      * Returns the link to fetch the image using the image proxy.
      *
      * @param string $link
-     * @return  string
-     * @since   3.0
+     * @return string
+     * @since 3.0
      */
     protected function getProxyLink($link)
     {
@@ -234,6 +237,10 @@ protected function getProxyLink($link)
         }
     }
 
+    /**
+     * @param string $src
+     * @return bool
+     */
     protected function isAllowedOrigin($src)
     {
         static $matcher = null;
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodePre.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodePre.class.php
index eeaf583aced..f7d6439b231 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodePre.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodePre.class.php
@@ -50,9 +50,7 @@ public function process(array $elements, AbstractHtmlNodeProcessor $htmlNodeProc
                     $context = $htmlNodeProcessor->getHtmlProcessor()->getContext();
                     $prefix = '';
                     // Create a unique prefix if possible
-                    if (isset($context['objectType']) && isset($context['objectID'])) {
-                        $prefix = \str_replace('.', '_', $context['objectType']) . '_' . $context['objectID'] . '_';
-                    }
+                    $prefix = \str_replace('.', '_', $context['objectType']) . '_' . $context['objectID'] . '_';
                     [$nodeIdentifier, $tagName] = $htmlNodeProcessor->getWcfNodeIdentifer();
                     $htmlNodeProcessor->addNodeData($this, $nodeIdentifier, [
                         'content' => $element->textContent,
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeProcessor.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeProcessor.class.php
index 347b573faf2..8186fc81f89 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeProcessor.class.php
@@ -52,9 +52,6 @@ class HtmlOutputNodeProcessor extends AbstractHtmlNodeProcessor
      */
     public static $plainTextNewlineTags = ['br', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'li', 'td', 'tr'];
 
-    /**
-     * HtmlOutputNodeProcessor constructor.
-     */
     public function __construct()
     {
         $this->sourceBBCodes = BBCodeParser::getInstance()->getSourceBBCodes();
@@ -64,6 +61,7 @@ public function __construct()
      * Sets the desired output type.
      *
      * @param string $outputType desired output type
+     * @return void
      */
     public function setOutputType($outputType)
     {
@@ -73,7 +71,7 @@ public function setOutputType($outputType)
     /**
      * Returns the current output type.
      *
-     * @return  string
+     * @return string
      */
     public function getOutputType()
     {
@@ -210,6 +208,7 @@ public function getHtml()
      * Enables the keyword highlighting.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableKeywordHighlighting($enable = true)
     {
@@ -218,6 +217,8 @@ public function enableKeywordHighlighting($enable = true)
 
     /**
      * Executes the keyword highlighting.
+     *
+     * @return void
      */
     protected function highlightKeywords()
     {
@@ -327,7 +328,7 @@ protected function removeTextFormatting(): void
         foreach ($elementsWithStyles as $element) {
             $style = $element->getAttribute("style");
             $values = \array_map(
-                static fn (string $value) => StringUtil::trim($value),
+                static fn(string $value) => StringUtil::trim($value),
                 \explode(";", $style)
             );
 
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeWoltlabQuote.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeWoltlabQuote.class.php
index f8e24f034ab..e042d440275 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeWoltlabQuote.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputNodeWoltlabQuote.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\html\output\node;
 
+use wcf\data\user\UserProfile;
 use wcf\system\application\ApplicationHandler;
 use wcf\system\html\node\AbstractHtmlNodeProcessor;
 use wcf\system\message\embedded\object\MessageEmbeddedObjectManager;
@@ -97,6 +98,7 @@ public function replaceTag(array $data)
         if ($data['author'] && !$externalQuoteLink) {
             $quoteAuthorLC = \mb_strtolower(StringUtil::decodeHTML($data['author']));
             foreach (MessageEmbeddedObjectManager::getInstance()->getObjects('com.woltlab.wcf.quote') as $user) {
+                \assert($user instanceof UserProfile);
                 if (\mb_strtolower($user->username) == $quoteAuthorLC) {
                     $quoteAuthorObject = $user;
                     break;
diff --git a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputUnfurlUrlNode.class.php b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputUnfurlUrlNode.class.php
index 6037ace834e..0e13d237869 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputUnfurlUrlNode.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/HtmlOutputUnfurlUrlNode.class.php
@@ -20,6 +20,9 @@
  */
 class HtmlOutputUnfurlUrlNode extends AbstractHtmlOutputNode
 {
+    /**
+     * @var string[]
+     */
     private static $disableUnfurlingForContext = ['com.woltlab.wcf.user.signature'];
 
     /**
diff --git a/wcfsetup/install/files/lib/system/html/output/node/IHtmlOutputNode.class.php b/wcfsetup/install/files/lib/system/html/output/node/IHtmlOutputNode.class.php
index 52252b031b6..2b11e2bd2a1 100644
--- a/wcfsetup/install/files/lib/system/html/output/node/IHtmlOutputNode.class.php
+++ b/wcfsetup/install/files/lib/system/html/output/node/IHtmlOutputNode.class.php
@@ -18,6 +18,7 @@ interface IHtmlOutputNode extends IHtmlNode
      * Sets the desired output type.
      *
      * @param string $outputType desired output type
+     * @return void
      */
     public function setOutputType($outputType);
 }
diff --git a/wcfsetup/install/files/lib/system/html/simple/HtmlSimpleParser.class.php b/wcfsetup/install/files/lib/system/html/simple/HtmlSimpleParser.class.php
index 3df3dacc41d..2b1b9b9f32e 100644
--- a/wcfsetup/install/files/lib/system/html/simple/HtmlSimpleParser.class.php
+++ b/wcfsetup/install/files/lib/system/html/simple/HtmlSimpleParser.class.php
@@ -5,6 +5,7 @@
 use wcf\system\message\embedded\object\ISimpleMessageEmbeddedObjectHandler;
 use wcf\system\message\embedded\object\MessageEmbeddedObjectManager;
 use wcf\system\SingletonFactory;
+use wcf\util\ArrayUtil;
 
 /**
  * Parses content for simple placeholders.
@@ -18,7 +19,7 @@ class HtmlSimpleParser extends SingletonFactory
 {
     /**
      * embedded object context
-     * @var array
+     * @var array{objectType: string, objectID: int}
      */
     protected $context = [
         'objectType' => '',
@@ -26,7 +27,7 @@ class HtmlSimpleParser extends SingletonFactory
     ];
 
     /**
-     * @var ISimpleMessageEmbeddedObjectHandler[]
+     * @var array<string, ISimpleMessageEmbeddedObjectHandler>
      */
     protected $handlers = [];
 
@@ -49,6 +50,7 @@ protected function init()
      *
      * @param string $objectType object type identifier
      * @param int $objectID object id
+     * @return void
      */
     public function setContext($objectType, $objectID)
     {
@@ -66,7 +68,7 @@ public function setContext($objectType, $objectID)
      * @param string $objectType object type identifier
      * @param int $objectID object id
      * @param string $message message content
-     * @return      bool         true if there is at least one embedded content found
+     * @return bool true if there is at least one embedded content found
      */
     public function parse($objectType, $objectID, $message)
     {
@@ -90,6 +92,7 @@ public function parse($objectType, $objectID, $message)
 
         $embeddedContent = [];
         foreach ($data as $handler => $values) {
+            $values = ArrayUtil::toIntegerArray($values);
             $values = $this->handlers[$handler]->validateValues($objectType, $objectID, $values);
             if (!empty($values)) {
                 $embeddedContent[$this->handlers[$handler]->objectTypeID] = \array_unique($values);
@@ -106,7 +109,7 @@ public function parse($objectType, $objectID, $message)
      * @param string $objectType object type identifier
      * @param int $objectID object id
      * @param string $message message content
-     * @return      string          parsed and replaced string
+     * @return string parsed and replaced string
      */
     public function replaceTags($objectType, $objectID, $message)
     {
@@ -123,8 +126,13 @@ public function replaceTags($objectType, $objectID, $message)
     /**
      * Replaces a placeholder.
      *
-     * @param array $data placeholder data
-     * @return      string          placeholder replacement
+     * @param array{
+     *  attributes: array<string, string>,
+     *  handler: string,
+     *  raw: string,
+     *  value: string,
+     * } $data placeholder data
+     * @return string placeholder replacement
      */
     public function replaceTag(array $data)
     {
@@ -155,7 +163,7 @@ public function replaceTag(array $data)
      * without causing conflicts with existing syntax.
      *
      * @param string $template template content
-     * @return      string          template content with custom template plugin
+     * @return string template content with custom template plugin
      */
     public function parseTemplate($template)
     {
@@ -176,7 +184,12 @@ public function parseTemplate($template)
      * Parses the attribute string and return individual components.
      *
      * @param string $attributesString attributes string, e.g. `foo="1" bar="baz"`
-     * @return      array           list of individual components
+     * @return array{
+     *  attributes: array<string, string>,
+     *  handler: string,
+     *  raw: string,
+     *  value: string,
+     * }
      */
     protected function parseAttributes($attributesString)
     {
diff --git a/wcfsetup/install/files/lib/system/html/toc/HtmlTocItem.class.php b/wcfsetup/install/files/lib/system/html/toc/HtmlTocItem.class.php
index edc36bbde83..c2589eb074a 100644
--- a/wcfsetup/install/files/lib/system/html/toc/HtmlTocItem.class.php
+++ b/wcfsetup/install/files/lib/system/html/toc/HtmlTocItem.class.php
@@ -9,18 +9,33 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
+ * @implements \RecursiveIterator<int, self>
  */
 class HtmlTocItem implements \Countable, \RecursiveIterator
 {
-    /** @var HtmlTocItem[] */
+    /**
+     * @var HtmlTocItem[]
+     */
     protected $children = [];
 
+    /**
+     * @var string
+     */
     protected $id = '';
 
+    /**
+     * @var int
+     */
     protected $level = 0;
 
+    /**
+     * @var string
+     */
     protected $title = '';
 
+    /**
+     * @var int
+     */
     protected $depth = 0;
 
     /**
@@ -29,9 +44,16 @@ class HtmlTocItem implements \Countable, \RecursiveIterator
      */
     private $position = 0;
 
-    /** @var HtmlTocItem */
+    /**
+     * @var ?HtmlTocItem
+     */
     private $parent;
 
+    /**
+     * @param int $level
+     * @param string $id
+     * @param string $title
+     */
     public function __construct($level, $id, $title)
     {
         $this->level = $level;
@@ -39,11 +61,17 @@ public function __construct($level, $id, $title)
         $this->title = $title;
     }
 
+    /**
+     * @return string
+     */
     public function getID()
     {
         return $this->id;
     }
 
+    /**
+     * @return int
+     */
     public function getLevel()
     {
         return $this->level;
@@ -62,25 +90,36 @@ public function getTitle(): string
         }, $this->title);
     }
 
+    /**
+     * @param HtmlTocItem $parent
+     * @return void
+     */
     public function setParent($parent)
     {
         $this->parent = $parent;
     }
 
     /**
-     * @return HtmlTocItem|null
+     * @return ?HtmlTocItem
      */
     public function getParent()
     {
         return $this->parent;
     }
 
+    /**
+     * @return void
+     */
     public function addChild(self $child)
     {
         $this->children[] = $child;
         $child->setParent($this);
     }
 
+    /**
+     * @param int $depth
+     * @return void
+     */
     public function setDepth($depth)
     {
         $this->depth = $depth;
@@ -170,7 +209,7 @@ public function key(): int
     }
 
     /**
-     * @inheritDoc
+     * @return \RecursiveIterator<int, self>
      */
     public function getChildren(): \RecursiveIterator
     {
@@ -185,6 +224,9 @@ public function hasChildren(): bool
         return \count($this->children) > 0;
     }
 
+    /**
+     * @return \RecursiveIteratorIterator<$this>
+     */
     public function getIterator()
     {
         return new \RecursiveIteratorIterator($this, \RecursiveIteratorIterator::SELF_FIRST);
diff --git a/wcfsetup/install/files/lib/system/image/adapter/GDImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/GDImageAdapter.class.php
index 528cbfe316d..4a902b1d7f2 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/GDImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/GDImageAdapter.class.php
@@ -11,6 +11,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements IImageAdapter<\GdImage>
+ * @implements IWebpImageAdapter<\GdImage>
  */
 class GDImageAdapter implements IImageAdapter, IWebpImageAdapter
 {
@@ -22,7 +24,7 @@ class GDImageAdapter implements IImageAdapter, IWebpImageAdapter
 
     /**
      * red, green, blue data of the active color
-     * @var array
+     * @var array{red: int, green: int, blue: int}|array{}
      */
     protected $colorData = [];
 
@@ -62,6 +64,7 @@ public function __construct()
     /**
      * Returns whether the given image is a valid GD resource / GD object
      *
+     * @param mixed $image
      * @return  bool
      */
     public function isImage($image)
diff --git a/wcfsetup/install/files/lib/system/image/adapter/IImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/IImageAdapter.class.php
index cf8c97f692b..e0154d86e86 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/IImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/IImageAdapter.class.php
@@ -8,14 +8,16 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @template T of object
  */
 interface IImageAdapter
 {
     /**
      * Loads an image resource.
      *
-     * @param mixed $image
+     * @param T $image
      * @param int $type
+     * @return void
      */
     public function load($image, $type = 0);
 
@@ -23,6 +25,7 @@ public function load($image, $type = 0);
      * Loads an image from file.
      *
      * @param string $file
+     * @return void
      */
     public function loadFile($file);
 
@@ -31,6 +34,7 @@ public function loadFile($file);
      *
      * @param int $width
      * @param int $height
+     * @return void
      */
     public function createEmptyImage($width, $height);
 
@@ -40,7 +44,7 @@ public function createEmptyImage($width, $height);
      * @param int $maxWidth
      * @param int $maxHeight
      * @param bool $preserveAspectRatio
-     * @return  mixed
+     * @return mixed
      */
     public function createThumbnail($maxWidth, $maxHeight, $preserveAspectRatio = true);
 
@@ -51,7 +55,8 @@ public function createThumbnail($maxWidth, $maxHeight, $preserveAspectRatio = tr
      * @param int $originY
      * @param int $width
      * @param int $height
-     * @see     \wcf\system\image\adapter\IImageAdapter::getImage()
+     * @return void
+     * @see \wcf\system\image\adapter\IImageAdapter::getImage()
      */
     public function clip($originX, $originY, $width, $height);
 
@@ -64,7 +69,8 @@ public function clip($originX, $originY, $width, $height);
      * @param int $originHeight
      * @param int $targetWidth
      * @param int $targetHeight
-     * @see     \wcf\system\image\adapter\IImageAdapter::getImage()
+     * @return void
+     * @see \wcf\system\image\adapter\IImageAdapter::getImage()
      */
     public function resize($originX, $originY, $originWidth, $originHeight, $targetWidth, $targetHeight);
 
@@ -75,8 +81,9 @@ public function resize($originX, $originY, $originWidth, $originHeight, $targetW
      * @param int $startY
      * @param int $endX
      * @param int $endY
-     * @see     \wcf\system\image\adapter\IImageAdapter::getImage()
-     * @see     \wcf\system\image\adapter\IImageAdapter::setColor()
+     * @return void
+     * @see \wcf\system\image\adapter\IImageAdapter::getImage()
+     * @see \wcf\system\image\adapter\IImageAdapter::setColor()
      */
     public function drawRectangle($startX, $startY, $endX, $endY);
 
@@ -89,8 +96,9 @@ public function drawRectangle($startX, $startY, $endX, $endY);
      * @param string $font path to TrueType font file
      * @param int $size font size
      * @param float $opacity
-     * @see     \wcf\system\image\adapter\IImageAdapter::getImage()
-     * @see     \wcf\system\image\adapter\IImageAdapter::setColor()
+     * @return void
+     * @see \wcf\system\image\adapter\IImageAdapter::getImage()
+     * @see \wcf\system\image\adapter\IImageAdapter::setColor()
      */
     public function drawText($text, $x, $y, $font, $size, $opacity = 1.0);
 
@@ -106,6 +114,7 @@ public function drawText($text, $x, $y, $font, $size, $opacity = 1.0);
      * @param string $font path to TrueType font file
      * @param int $size font size
      * @param float $opacity
+     * @return void
      */
     public function drawTextRelative($text, $position, $margin, $offsetX, $offsetY, $font, $size, $opacity = 1.0);
 
@@ -116,8 +125,7 @@ public function drawTextRelative($text, $position, $margin, $offsetX, $offsetY,
      * @param int $margin
      * @param string $font path to TrueType font file
      * @param int $size font size
-     * @return  int
-     * @return  bool
+     * @return bool
      */
     public function textFitsImage($text, $margin, $font, $size);
 
@@ -129,7 +137,7 @@ public function textFitsImage($text, $margin, $font, $size);
      * @param int $margin
      * @param string $font path to TrueType font file
      * @param int $size font size
-     * @return  int
+     * @return int
      */
     public function adjustFontSize($text, $margin, $font, $size);
 
@@ -139,13 +147,14 @@ public function adjustFontSize($text, $margin, $font, $size);
      * @param int $red
      * @param int $green
      * @param int $blue
+     * @return void
      */
     public function setColor($red, $green, $blue);
 
     /**
      * Returns true if a color has been set.
      *
-     * @return  bool
+     * @return bool
      */
     public function hasColor();
 
@@ -155,42 +164,44 @@ public function hasColor();
      * @param int $red
      * @param int $green
      * @param int $blue
+     * @return void
      */
     public function setTransparentColor($red, $green, $blue);
 
     /**
      * Writes an image to disk.
      *
-     * @param mixed $image
-     * @param string $filename
+     * @param T|string $image
+     * @param ?string $filename
+     * @return void
      */
     public function writeImage($image, $filename);
 
     /**
      * Returns image resource.
      *
-     * @return  mixed
+     * @return mixed
      */
     public function getImage();
 
     /**
      * Returns image width.
      *
-     * @return  int
+     * @return int
      */
     public function getWidth();
 
     /**
      * Returns image height
      *
-     * @return  int
+     * @return int
      */
     public function getHeight();
 
     /**
      * Returns the image type (GD only)
      *
-     * @return  int
+     * @return int
      */
     public function getType();
 
@@ -209,6 +220,7 @@ public function rotate($degrees);
      * @param int $x
      * @param int $y
      * @param float $opacity
+     * @return void
      */
     public function overlayImage($file, $x, $y, $opacity);
 
@@ -219,12 +231,14 @@ public function overlayImage($file, $x, $y, $opacity);
      * @param string $position
      * @param int $margin
      * @param float $opacity
+     * @return void
      */
     public function overlayImageRelative($file, $position, $margin, $opacity);
 
     /**
      * Saves an image using a different file type.
      *
+     * @param T $image
      * @since 5.4
      */
     public function saveImageAs($image, string $filename, string $type, int $quality = 100): void;
@@ -232,7 +246,7 @@ public function saveImageAs($image, string $filename, string $type, int $quality
     /**
      * Determines if an image adapter is supported.
      *
-     * @return  bool
+     * @return bool
      */
     public static function isSupported();
 }
diff --git a/wcfsetup/install/files/lib/system/image/adapter/IMemoryAwareImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/IMemoryAwareImageAdapter.class.php
index 2b47fc2d732..43270df5994 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/IMemoryAwareImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/IMemoryAwareImageAdapter.class.php
@@ -10,6 +10,8 @@
  * @copyright   2001-2020 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.3
+ * @template T of object
+ * @extends IImageAdapter<T>
  */
 interface IMemoryAwareImageAdapter extends IImageAdapter
 {
diff --git a/wcfsetup/install/files/lib/system/image/adapter/IWebpImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/IWebpImageAdapter.class.php
index 31c24ea60a6..7ac822433d6 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/IWebpImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/IWebpImageAdapter.class.php
@@ -10,6 +10,8 @@
  * @copyright 2001-2021 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 5.4
+ * @template T of object
+ * @extends IImageAdapter<T>
  */
 interface IWebpImageAdapter extends IImageAdapter
 {
diff --git a/wcfsetup/install/files/lib/system/image/adapter/ImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/ImageAdapter.class.php
index b4f0dad3891..06673b268e8 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/ImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/ImageAdapter.class.php
@@ -12,12 +12,14 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements IImageAdapter<\stdClass>
+ * @implements IMemoryAwareImageAdapter<\stdClass>
  */
 class ImageAdapter implements IImageAdapter, IMemoryAwareImageAdapter, ISingleFrameImageAdapter
 {
     /**
      * IImageAdapter object
-     * @var IImageAdapter
+     * @var IImageAdapter<\stdClass>
      */
     protected $adapter;
 
@@ -352,7 +354,7 @@ public function overlayImageRelative($file, $position, $margin, $opacity)
 
         $adapterClassName = \get_class($this->adapter);
 
-        /** @var IImageAdapter $overlayImage */
+        /** @var IImageAdapter<\stdClass> $overlayImage */
         $overlayImage = new $adapterClassName();
         $overlayImage->loadFile($file);
         $overlayHeight = $overlayImage->getHeight();
diff --git a/wcfsetup/install/files/lib/system/image/adapter/ImagickImageAdapter.class.php b/wcfsetup/install/files/lib/system/image/adapter/ImagickImageAdapter.class.php
index febfe3ecf05..0bd80a3c0bf 100644
--- a/wcfsetup/install/files/lib/system/image/adapter/ImagickImageAdapter.class.php
+++ b/wcfsetup/install/files/lib/system/image/adapter/ImagickImageAdapter.class.php
@@ -13,6 +13,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements IImageAdapter<\Imagick>
+ * @implements IWebpImageAdapter<\Imagick>
  */
 class ImagickImageAdapter implements IImageAdapter, ISingleFrameImageAdapter, IWebpImageAdapter
 {
@@ -49,6 +51,8 @@ class ImagickImageAdapter implements IImageAdapter, ISingleFrameImageAdapter, IW
 
     /**
      * List of image format that support animations.
+     *
+     * @var string[]
      */
     protected static array $animatedFormats = ['GIF', 'WEBP'];
 
@@ -69,6 +73,7 @@ public function __construct()
      */
     public function load($image, $type = 0)
     {
+        // @phpstan-ignore instanceof.alwaysTrue
         if (!($image instanceof \Imagick)) {
             throw new SystemException("Object must be an instance of Imagick");
         }
@@ -108,6 +113,8 @@ public function loadSingleFrameFromFile(string $filename): void
 
     /**
      * Reads width and height of the image.
+     *
+     * @return void
      */
     protected function readImageDimensions()
     {
@@ -509,6 +516,7 @@ public static function getVersion()
      */
     public function saveImageAs($image, string $filename, string $type, int $quality = 100): void
     {
+        // @phpstan-ignore instanceof.alwaysTrue
         if (!($image instanceof \Imagick)) {
             throw new \InvalidArgumentException("Given image is not a valid Imagick-object.");
         }
diff --git a/wcfsetup/install/files/lib/system/importer/AbstractACLImporter.class.php b/wcfsetup/install/files/lib/system/importer/AbstractACLImporter.class.php
index 9f055f1b201..23a247383cc 100644
--- a/wcfsetup/install/files/lib/system/importer/AbstractACLImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/AbstractACLImporter.class.php
@@ -27,7 +27,7 @@ class AbstractACLImporter extends AbstractImporter
 
     /**
      * available options
-     * @var array
+     * @var array<string, int>
      */
     protected $options = [];
 
diff --git a/wcfsetup/install/files/lib/system/importer/AbstractImporter.class.php b/wcfsetup/install/files/lib/system/importer/AbstractImporter.class.php
index f29d965562d..e58317c8bd4 100644
--- a/wcfsetup/install/files/lib/system/importer/AbstractImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/AbstractImporter.class.php
@@ -11,6 +11,11 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type I18nValue array{
+ *  languageID: int,
+ *  languageItem: string,
+ *  languageItemValue: string,
+ * }
  */
 abstract class AbstractImporter implements IImporter
 {
@@ -31,9 +36,10 @@ public function getClassName()
     /**
      * Imports a list of language items.
      *
-     * @param string[][] $items
+     * @param I18nValue[] $items
      * @param string $languageCategory
      * @param string $package
+     * @return void
      */
     protected function importI18nValues(array $items, $languageCategory, $package)
     {
@@ -62,7 +68,7 @@ protected function importI18nValues(array $items, $languageCategory, $package)
      * Returns the language category id.
      *
      * @param string $languageCategory
-     * @return      int
+     * @return int
      */
     protected function getLanguageCategoryID($languageCategory)
     {
diff --git a/wcfsetup/install/files/lib/system/importer/IImporter.class.php b/wcfsetup/install/files/lib/system/importer/IImporter.class.php
index bf0412c2060..f1944042682 100644
--- a/wcfsetup/install/files/lib/system/importer/IImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/IImporter.class.php
@@ -15,8 +15,8 @@ interface IImporter
      * Imports a data set.
      *
      * @param mixed $oldID
-     * @param array $data
-     * @param array $additionalData
+     * @param mixed[] $data
+     * @param mixed[] $additionalData
      * @return  mixed       new id
      */
     public function import($oldID, array $data, array $additionalData = []);
diff --git a/wcfsetup/install/files/lib/system/importer/ImportHandler.class.php b/wcfsetup/install/files/lib/system/importer/ImportHandler.class.php
index 98d81e2961e..594d5c2b90b 100644
--- a/wcfsetup/install/files/lib/system/importer/ImportHandler.class.php
+++ b/wcfsetup/install/files/lib/system/importer/ImportHandler.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\importer;
 
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\cache\CacheHandler;
 use wcf\system\database\exception\DatabaseException;
@@ -22,19 +23,19 @@ class ImportHandler extends SingletonFactory implements IAJAXInvokeAction
 {
     /**
      * id map cache
-     * @var array
+     * @var array<int, array<mixed, ?int>>
      */
     protected $idMappingCache = [];
 
     /**
      * list of available importers
-     * @var array
+     * @var array<string, ObjectType>
      */
     protected $objectTypes = [];
 
     /**
      * list of available importer processors
-     * @var array
+     * @var array<string, IImporter>
      */
     protected $importers = [];
 
@@ -68,8 +69,8 @@ protected function init()
      * Returns a data importer.
      *
      * @param string $type
-     * @return  IImporter
-     * @throws  SystemException
+     * @return IImporter
+     * @throws SystemException
      */
     public function getImporter($type)
     {
@@ -89,7 +90,7 @@ public function getImporter($type)
      *
      * @param string $type
      * @param mixed $oldID
-     * @return  int|null
+     * @return ?int
      */
     public function getNewID($type, $oldID)
     {
@@ -137,6 +138,7 @@ public function getNewID($type, $oldID)
      * @param string $type
      * @param int $oldID
      * @param int $newID
+     * @return void
      */
     public function saveNewID($type, $oldID, $newID)
     {
@@ -167,6 +169,8 @@ public function saveNewID($type, $oldID, $newID)
 
     /**
      * Validates accessibility of resetMapping().
+     *
+     * @return void
      */
     public function validateResetMapping()
     {
@@ -179,6 +183,8 @@ public function validateResetMapping()
 
     /**
      * Resets the mapping.
+     *
+     * @return void
      */
     public function resetMapping()
     {
@@ -193,6 +199,7 @@ public function resetMapping()
      * Sets the user merge mode.
      *
      * @param int $mode
+     * @return void
      */
     public function setUserMergeMode($mode)
     {
@@ -202,7 +209,7 @@ public function setUserMergeMode($mode)
     /**
      * Returns the user merge mode.
      *
-     * @return  int
+     * @return int
      */
     public function getUserMergeMode()
     {
@@ -213,6 +220,7 @@ public function getUserMergeMode()
      * Sets the import hash.
      *
      * @param string $hash
+     * @return void
      */
     public function setImportHash($hash)
     {
diff --git a/wcfsetup/install/files/lib/system/importer/UserGroupImporter.class.php b/wcfsetup/install/files/lib/system/importer/UserGroupImporter.class.php
index 91a025dc0b7..375378d8128 100644
--- a/wcfsetup/install/files/lib/system/importer/UserGroupImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/UserGroupImporter.class.php
@@ -84,6 +84,9 @@ public function import($oldID, array $data, array $additionalData = [])
         return $newGroupID;
     }
 
+    /**
+     * @return UserGroupOptionHandler
+     */
     protected function getOptionHandler()
     {
         $optionHandler = new UserGroupOptionHandler(false, '', '');
diff --git a/wcfsetup/install/files/lib/system/importer/UserImporter.class.php b/wcfsetup/install/files/lib/system/importer/UserImporter.class.php
index 7980fc9e456..7bacc3de996 100644
--- a/wcfsetup/install/files/lib/system/importer/UserImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/UserImporter.class.php
@@ -32,7 +32,10 @@ class UserImporter extends AbstractImporter
 
     /**
      * @since 5.4
-     * @var array
+     * @var array{
+     *  notActivated: int[],
+     *  activated: int[],
+     * }
      */
     protected $defaultGroups = [
         'notActivated' => [],
diff --git a/wcfsetup/install/files/lib/system/importer/UserOptionImporter.class.php b/wcfsetup/install/files/lib/system/importer/UserOptionImporter.class.php
index 984f2b67281..4802bc83741 100644
--- a/wcfsetup/install/files/lib/system/importer/UserOptionImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/UserOptionImporter.class.php
@@ -104,6 +104,7 @@ public function import($oldID, array $data, array $additionalData = [])
      * Creates the given category if necessary.
      *
      * @param string $name
+     * @return void
      */
     protected function createCategory($name)
     {
diff --git a/wcfsetup/install/files/lib/system/interaction/InteractionContextMenuView.class.php b/wcfsetup/install/files/lib/system/interaction/InteractionContextMenuView.class.php
index 6b31233738f..02e828f2e23 100644
--- a/wcfsetup/install/files/lib/system/interaction/InteractionContextMenuView.class.php
+++ b/wcfsetup/install/files/lib/system/interaction/InteractionContextMenuView.class.php
@@ -54,6 +54,9 @@ public function renderInitialization(string $containerId): string
         );
     }
 
+    /**
+     * @return (IInteraction|Divider)[]
+     */
     public function getInteractionsForObject(DatabaseObject $object): array
     {
         $interactions = \array_filter(
@@ -64,6 +67,9 @@ public function getInteractionsForObject(DatabaseObject $object): array
         return $this->removeObsoleteDividers($interactions);
     }
 
+    /**
+     * @return (IInteraction|Divider)[]
+     */
     public function getInteractions(): array
     {
         return $this->provider->getInteractions();
diff --git a/wcfsetup/install/files/lib/system/io/AtomicWriter.class.php b/wcfsetup/install/files/lib/system/io/AtomicWriter.class.php
index 87f3ad205d4..0e0e86278e3 100644
--- a/wcfsetup/install/files/lib/system/io/AtomicWriter.class.php
+++ b/wcfsetup/install/files/lib/system/io/AtomicWriter.class.php
@@ -72,6 +72,8 @@ public function __destruct()
     /**
      * Closes the file, while discarding any written data, noop if the
      * file is already closed or flushed.
+     *
+     * @return void
      */
     public function close()
     {
@@ -87,6 +89,8 @@ public function close()
     /**
      * Persists the written data into the target file. The flush is atomic
      * if the underlying storage supports an atomic rename.
+     *
+     * @return void
      */
     public function flush()
     {
@@ -116,6 +120,9 @@ public function flush()
 
     /**
      * @inheritDoc
+     * @param string $function
+     * @param mixed[] $arguments
+     * @return mixed
      */
     public function __call($function, $arguments)
     {
diff --git a/wcfsetup/install/files/lib/system/io/FTP.class.php b/wcfsetup/install/files/lib/system/io/FTP.class.php
index d6e52735526..0c0181b0e1e 100644
--- a/wcfsetup/install/files/lib/system/io/FTP.class.php
+++ b/wcfsetup/install/files/lib/system/io/FTP.class.php
@@ -37,7 +37,7 @@ public function __construct($host = 'localhost', $port = 21, $timeout = 30)
      * Calls the specified function on the open ftp connection.
      *
      * @param string $function
-     * @param array $arguments
+     * @param mixed[] $arguments
      * @return  mixed
      * @throws  SystemException
      */
diff --git a/wcfsetup/install/files/lib/system/io/File.class.php b/wcfsetup/install/files/lib/system/io/File.class.php
index f46401c2f11..03614c69df7 100644
--- a/wcfsetup/install/files/lib/system/io/File.class.php
+++ b/wcfsetup/install/files/lib/system/io/File.class.php
@@ -32,7 +32,7 @@
  * @method int      puts($string, $length = null)       alias of `write`
  * @method string   read($length)
  * @method int      seek($offset, $whence = 0)
- * @method array    stat()
+ * @method array<string, mixed> stat()
  * @method bool     sync()
  * @method int      tell()
  * @method bool     touch($time = 0, $atime = 0)        note: default value of `$time` actually is `time()`
@@ -57,7 +57,7 @@ class File
      *
      * @param string $filename
      * @param string $mode
-     * @param array $options
+     * @param array<string, mixed> $options
      * @throws  SystemException
      */
     public function __construct($filename, $mode = 'wb', $options = [])
@@ -79,7 +79,7 @@ public function __construct($filename, $mode = 'wb', $options = [])
      * Do not call this function directly. Use $file->write('') instead.
      *
      * @param string $function
-     * @param array $arguments
+     * @param mixed[] $arguments
      * @return  mixed
      * @throws  SystemException
      */
diff --git a/wcfsetup/install/files/lib/system/io/GZipFile.class.php b/wcfsetup/install/files/lib/system/io/GZipFile.class.php
index 857eb9d6fb0..f6f54d498fc 100644
--- a/wcfsetup/install/files/lib/system/io/GZipFile.class.php
+++ b/wcfsetup/install/files/lib/system/io/GZipFile.class.php
@@ -38,7 +38,7 @@ public function __construct($filename, $mode = 'wb')
      * Calls the specified function on the open file.
      *
      * @param string $function
-     * @param array $arguments
+     * @param mixed[] $arguments
      * @return  mixed
      * @throws  SystemException
      */
diff --git a/wcfsetup/install/files/lib/system/io/HttpFactory.class.php b/wcfsetup/install/files/lib/system/io/HttpFactory.class.php
index 9c8a39c411f..6e64f3d91b3 100644
--- a/wcfsetup/install/files/lib/system/io/HttpFactory.class.php
+++ b/wcfsetup/install/files/lib/system/io/HttpFactory.class.php
@@ -80,6 +80,7 @@ public static function makeClientWithTimeout(float $timeout): ClientInterface
      * specifically removed by passing appropriate options.
      *
      * @see Client
+     * @param array<string, mixed> $options
      * @return PsrClientInterface&ClientInterface
      */
     public static function makeClient(array $options = []): ClientInterface
diff --git a/wcfsetup/install/files/lib/system/io/IArchive.class.php b/wcfsetup/install/files/lib/system/io/IArchive.class.php
index d4de64474d8..fd116b147d6 100644
--- a/wcfsetup/install/files/lib/system/io/IArchive.class.php
+++ b/wcfsetup/install/files/lib/system/io/IArchive.class.php
@@ -8,13 +8,23 @@
  * @author  Tim Duesterhus
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type FileInfo array{
+ *  compressedSize?: int,
+ *  crc32: int,
+ *  filename: string,
+ *  mtime: int,
+ *  offset: int,
+ *  size: int,
+ *  type: 'file'|'folder'|'symlink',
+ *  index: int,
+ * }&mixed[]
  */
 interface IArchive
 {
     /**
      * Returns the table of contents (TOC) list for this archive.
      *
-     * @return array list of contents
+     * @return array<int, FileInfo> list of contents
      */
     public function getContentList();
 
@@ -23,7 +33,7 @@ public function getContentList();
      * in the archive.
      *
      * @param mixed $index index or name of the requested file
-     * @return array
+     * @return FileInfo
      */
     public function getFileInfo($index);
 
diff --git a/wcfsetup/install/files/lib/system/io/RemoteFile.class.php b/wcfsetup/install/files/lib/system/io/RemoteFile.class.php
index aa1fc787846..d2cb367c9fa 100644
--- a/wcfsetup/install/files/lib/system/io/RemoteFile.class.php
+++ b/wcfsetup/install/files/lib/system/io/RemoteFile.class.php
@@ -51,7 +51,7 @@ class RemoteFile extends File
      * @param string $host
      * @param int $port
      * @param int $timeout
-     * @param array $options
+     * @param array<string, mixed> $options
      * @throws  SystemException
      */
     public function __construct($host, $port, $timeout = 30, $options = [])
@@ -157,6 +157,7 @@ public function hasTLSSupport()
     }
 
     /**
+     * @return bool
      * @deprecated 6.0 This method is effectively returning bogus data, because the majority of TLS communication uses Guzzle/cURL.
      */
     public static function supportsSSL()
@@ -177,6 +178,7 @@ public static function supportsSSL()
     }
 
     /**
+     * @return void
      * @deprecated 6.0 See RemoteFile::supportsSSL(). The implementation is a noop.
      */
     public static function disableSSL()
diff --git a/wcfsetup/install/files/lib/system/io/Tar.class.php b/wcfsetup/install/files/lib/system/io/Tar.class.php
index 87a90ee5b04..6eb64363254 100644
--- a/wcfsetup/install/files/lib/system/io/Tar.class.php
+++ b/wcfsetup/install/files/lib/system/io/Tar.class.php
@@ -19,6 +19,7 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type FileInfo from IArchive
  */
 class Tar implements IArchive
 {
@@ -30,7 +31,7 @@ class Tar implements IArchive
 
     /**
      * content of the tar file
-     * @var array
+     * @var array<int, FileInfo>
      */
     protected $contentList = [];
 
@@ -70,6 +71,9 @@ class Tar implements IArchive
      */
     const CHUNK_SIZE = 8192;
 
+    /**
+     * @var array<string, int<0, 255>>
+     */
     private static array $asciiMap;
 
     /**
@@ -107,6 +111,8 @@ public function __destruct()
 
     /**
      * Opens the tar archive and stores filehandle.
+     *
+     * @return void
      */
     public function open()
     {
@@ -130,6 +136,8 @@ public function open()
 
     /**
      * Closes the opened file.
+     *
+     * @return void
      */
     public function close()
     {
@@ -264,6 +272,8 @@ public function extract($index, $destination)
     /**
      * Reads table of contents (TOC) from tar archive.
      * This does not get the entire to memory but only parts of it.
+     *
+     * @return void
      */
     protected function readContent()
     {
@@ -307,7 +317,7 @@ protected function readContent()
      * Unpacks file header for one file entry.
      *
      * @param string $binaryData
-     * @return  array|bool
+     * @return mixed[]|bool
      */
     protected function readHeader($binaryData)
     {
diff --git a/wcfsetup/install/files/lib/system/io/TarWriter.class.php b/wcfsetup/install/files/lib/system/io/TarWriter.class.php
index 6b65ca8fbca..13ddb0218b1 100644
--- a/wcfsetup/install/files/lib/system/io/TarWriter.class.php
+++ b/wcfsetup/install/files/lib/system/io/TarWriter.class.php
@@ -46,6 +46,8 @@ public function __construct($archiveName, $compress = false)
 
     /**
      * Writes the last 0 filled block for end of archive.
+     *
+     * @return void
      */
     protected function writeFooter()
     {
@@ -54,6 +56,8 @@ protected function writeFooter()
 
     /**
      * Creates the tar archive.
+     *
+     * @return void
      */
     public function create()
     {
diff --git a/wcfsetup/install/files/lib/system/io/Zip.class.php b/wcfsetup/install/files/lib/system/io/Zip.class.php
index 452bbd5b7df..fd71164d63a 100644
--- a/wcfsetup/install/files/lib/system/io/Zip.class.php
+++ b/wcfsetup/install/files/lib/system/io/Zip.class.php
@@ -11,6 +11,7 @@
  * @author  Tim Duesterhus
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type FileInfo from IArchive
  */
 class Zip extends File implements IArchive
 {
@@ -22,6 +23,9 @@ class Zip extends File implements IArchive
 
     const DATA_DESCRIPTOR_SIGNATURE = "\x50\x4b\x07\x08";
 
+    /**
+     * @var array{files: array<int, FileInfo>, eof: array<string, mixed[]>}
+     */
     protected $centralDirectory;
 
     /**
@@ -73,6 +77,7 @@ public function getFileInfo($index)
      * The directory-structure inside the .zip is preserved.
      *
      * @param string $destination where to extract
+     * @return void
      */
     public function extractAll($destination)
     {
@@ -148,6 +153,8 @@ public function extract($index, $destination)
 
     /**
      * Moves the file-pointer to the beginning of the Central Directory.
+     *
+     * @return void
      */
     protected function jumpToCentralDirectory()
     {
@@ -182,8 +189,8 @@ protected function jumpToCentralDirectory()
     /**
      * Reads the central directory and returns it.
      *
-     * @return  array
-     * @throws  SystemException
+     * @return array{files: array<int, FileInfo>, eof: array<string, mixed[]>}
+     * @throws SystemException
      */
     protected function readCentralDirectory()
     {
@@ -268,8 +275,8 @@ protected function readCentralDirectory()
      * This does not change the position of the file-pointer.
      *
      * @param int|false|null $offset where to start reading
-     * @return  bool
-     * @throws  SystemException
+     * @return bool
+     * @throws SystemException
      */
     public function isFile($offset = null)
     {
@@ -294,8 +301,8 @@ public function isFile($offset = null)
      * Reads a file and returns it.
      *
      * @param int|false|null $offset where to start reading
-     * @return  array
-     * @throws  SystemException
+     * @return mixed[]
+     * @throws SystemException
      */
     public function readFile($offset = null)
     {
@@ -391,7 +398,7 @@ public function readFile($offset = null)
      *
      * @param int $length Number of bytes to read
      * @param string $type Which type are the bytes of
-     * @return  mixed
+     * @return mixed
      */
     protected function readAndUnpack($length, $type)
     {
diff --git a/wcfsetup/install/files/lib/system/io/ZipWriter.class.php b/wcfsetup/install/files/lib/system/io/ZipWriter.class.php
index 404e168b4f6..830a6f3684b 100644
--- a/wcfsetup/install/files/lib/system/io/ZipWriter.class.php
+++ b/wcfsetup/install/files/lib/system/io/ZipWriter.class.php
@@ -14,14 +14,29 @@
  */
 class ZipWriter
 {
+    /**
+     * @var string[]
+     */
     protected $headers = [];
 
+    /**
+     * @var string[]
+     */
     protected $data = [];
 
+    /**
+     * @var string
+     */
     protected $endOfData = "\x50\x4b\x05\x06\x00\x00\x00\x00";
 
+    /**
+     * @var int
+     */
     protected $lastOffset = 0;
 
+    /**
+     * @var string
+     */
     protected $zipComment = '';
 
     /**
@@ -29,6 +44,7 @@ class ZipWriter
      *
      * @param string $name dirname
      * @param int $date
+     * @return void
      */
     public function addDir($name, $date = TIME_NOW)
     {
@@ -87,6 +103,7 @@ public function addDir($name, $date = TIME_NOW)
      * @param string $data content of the file
      * @param string $name filename
      * @param int $date file creation time as unix timestamp
+     * @return void
      */
     public function addFile($data, $name, $date = TIME_NOW)
     {
@@ -156,6 +173,7 @@ public function addFile($data, $name, $date = TIME_NOW)
      * Set Zip archive comment
      *
      * @param string $comment zip archive comment
+     * @return void
      */
     public function setArchiveComment($comment)
     {
@@ -165,7 +183,7 @@ public function setArchiveComment($comment)
     /**
      * Constructs the final Zip file structure and return it.
      *
-     * @return  string
+     * @return string
      */
     public function getFile()
     {
@@ -191,7 +209,7 @@ public function getFile()
      * Converts an unix timestamp to Zip file time.
      *
      * @param int $date unix timestamp
-     * @return  string
+     * @return string
      */
     protected static function getDosDatetime($date)
     {
diff --git a/wcfsetup/install/files/lib/system/io/http/RedirectGuard.class.php b/wcfsetup/install/files/lib/system/io/http/RedirectGuard.class.php
index 8b3635fc5c5..47100a494c5 100644
--- a/wcfsetup/install/files/lib/system/io/http/RedirectGuard.class.php
+++ b/wcfsetup/install/files/lib/system/io/http/RedirectGuard.class.php
@@ -20,20 +20,17 @@
  */
 final class RedirectGuard
 {
-    /**
-     * @var null|callable
-     */
-    private $next;
+    private readonly ?\Closure $next;
 
     /**
      * @param ?callable $next The next callback to call after validation succeeds.
      */
     public function __construct(?callable $next = null)
     {
-        $this->next = $next;
+        $this->next = $next ? \Closure::fromCallable($next) : null;
     }
 
-    public function __invoke(RequestInterface $request, ResponseInterface $response, UriInterface $uri)
+    public function __invoke(RequestInterface $request, ResponseInterface $response, UriInterface $uri): ?callable
     {
         if ($uri->getPort() !== null) {
             throw new BadResponseException(
@@ -46,5 +43,7 @@ public function __invoke(RequestInterface $request, ResponseInterface $response,
         if (($next = $this->next)) {
             return $next($request, $response, $uri);
         }
+
+        return null;
     }
 }
diff --git a/wcfsetup/install/files/lib/system/label/LabelHandler.class.php b/wcfsetup/install/files/lib/system/label/LabelHandler.class.php
index 038b610449d..5b86c22ff50 100644
--- a/wcfsetup/install/files/lib/system/label/LabelHandler.class.php
+++ b/wcfsetup/install/files/lib/system/label/LabelHandler.class.php
@@ -5,6 +5,7 @@
 use wcf\data\label\group\LabelGroup;
 use wcf\data\label\group\ViewableLabelGroup;
 use wcf\data\label\Label;
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\data\user\User;
 use wcf\system\cache\builder\LabelCacheBuilder;
@@ -19,18 +20,22 @@
  * @author  Alexander Ebert, Joshua Ruesweg
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type LabelCache from LabelCacheBuilder
  */
 class LabelHandler extends SingletonFactory
 {
     /**
      * cached list of object types
-     * @var mixed[][]
+     * @var array{
+     *  objectTypes: array<int, ObjectType>,
+     *  objectTypeNames: array<string, int>
+     * }
      */
     protected $cache;
 
     /**
      * list of label groups
-     * @var mixed[][]
+     * @var LabelCache
      */
     protected $labelGroups;
 
@@ -58,12 +63,12 @@ protected function init()
      * no such option exists.
      *
      * @param string $optionName
-     * @return  int|null
+     * @return ?int
      */
     public function getOptionID($optionName)
     {
         foreach ($this->labelGroups['options'] as $option) {
-            if ($option->optionName == $optionName) {
+            if ($option->optionName === $optionName) {
                 return $option->optionID;
             }
         }
@@ -76,7 +81,7 @@ public function getOptionID($optionName)
      * object.
      *
      * @param string $objectType
-     * @return  \wcf\data\object\type\ObjectType|null
+     * @return ?ObjectType
      */
     public function getObjectType($objectType)
     {
@@ -94,7 +99,7 @@ public function getObjectType($objectType)
      *
      * @param int[] $labelIDs
      * @param User $user
-     * @return  array
+     * @return array<int, bool>|array{}
      * @see     \wcf\system\label\LabelHandler::getPermissions()
      */
     public function validateCanView(array $labelIDs, ?User $user = null)
@@ -107,7 +112,7 @@ public function validateCanView(array $labelIDs, ?User $user = null)
      *
      * @param int[] $labelIDs
      * @param User $user
-     * @return  array
+     * @return array<int, bool>|array{}
      * @see     \wcf\system\label\LabelHandler::getPermissions()
      */
     public function validateCanUse(array $labelIDs, ?User $user = null)
@@ -121,7 +126,7 @@ public function validateCanUse(array $labelIDs, ?User $user = null)
      * @param string $optionName
      * @param int[] $labelIDs
      * @param User $user
-     * @return  array
+     * @return array<int, bool>|array{}
      * @throws  SystemException
      */
     public function getPermissions($optionName, array $labelIDs, ?User $user = null)
@@ -175,6 +180,7 @@ public function getPermissions($optionName, array $labelIDs, ?User $user = null)
      * @param int $objectTypeID
      * @param int $objectID
      * @param bool $validatePermissions
+     * @return void
      */
     public function setLabels(array $labelIDs, $objectTypeID, $objectID, $validatePermissions = true)
     {
@@ -222,6 +228,7 @@ public function setLabels(array $labelIDs, $objectTypeID, $objectID, $validatePe
      * @param int[] $labelIDs ids of the new labels
      * @param string $objectType label object type of the updated object
      * @param int $objectID id of the updated object
+     * @return void
      * @since   5.2
      */
     public function replaceLabels(array $groupIDs, array $labelIDs, $objectType, $objectID)
@@ -376,6 +383,7 @@ public function getLabelGroups(array $groupIDs = [], $validatePermissions = true
             $data[$groupID] = $this->labelGroups['groups'][$groupID];
         }
 
+        // @phpstan-ignore argument.type
         \uasort($data, [LabelGroup::class, 'sortLabelGroups']);
 
         return $data;
@@ -414,6 +422,7 @@ public function getLabelGroup($groupID)
      *
      * @param int $objectTypeID
      * @param int[] $objectIDs
+     * @return void
      */
     public function removeLabels($objectTypeID, array $objectIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/label/object/ArticleLabelObjectHandler.class.php b/wcfsetup/install/files/lib/system/label/object/ArticleLabelObjectHandler.class.php
index 0b8d826680a..509559d4fd0 100644
--- a/wcfsetup/install/files/lib/system/label/object/ArticleLabelObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/ArticleLabelObjectHandler.class.php
@@ -24,6 +24,7 @@ class ArticleLabelObjectHandler extends AbstractLabelObjectHandler
      * Sets the label groups available for the categories with the given ids.
      *
      * @param int[] $categoryIDs
+     * @return void
      */
     public function setCategoryIDs($categoryIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/label/object/ILabelObjectHandler.class.php b/wcfsetup/install/files/lib/system/label/object/ILabelObjectHandler.class.php
index b628dda1a2d..06225ed2faf 100644
--- a/wcfsetup/install/files/lib/system/label/object/ILabelObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/ILabelObjectHandler.class.php
@@ -17,16 +17,16 @@ interface ILabelObjectHandler
     /**
      * Returns a list of label group ids.
      *
-     * @param array $parameters
-     * @return  int[]
+     * @param mixed[] $parameters
+     * @return int[]
      */
     public function getLabelGroupIDs(array $parameters = []);
 
     /**
      * Returns a list of label groups.
      *
-     * @param array $parameters
-     * @return  ViewableLabelGroup[]
+     * @param mixed[] $parameters
+     * @return ViewableLabelGroup[]
      */
     public function getLabelGroups(array $parameters = []);
 
@@ -36,7 +36,7 @@ public function getLabelGroups(array $parameters = []);
      * @param int[] $labelIDs
      * @param string $optionName
      * @param bool $legacyReturnValue
-     * @return  mixed
+     * @return mixed
      */
     public function validateLabelIDs(array $labelIDs, $optionName = '', $legacyReturnValue = true);
 
@@ -46,6 +46,7 @@ public function validateLabelIDs(array $labelIDs, $optionName = '', $legacyRetur
      * @param int[] $labelIDs
      * @param int $objectID
      * @param bool $validatePermissions
+     * @return void
      * @see     \wcf\system\label\LabelHandler::setLabels()
      */
     public function setLabels(array $labelIDs, $objectID, $validatePermissions = true);
@@ -55,6 +56,7 @@ public function setLabels(array $labelIDs, $objectID, $validatePermissions = tru
      *
      * @param int $objectID
      * @param bool $validatePermissions
+     * @return void
      * @see     \wcf\system\label\LabelHandler::removeLabels()
      */
     public function removeLabels($objectID, $validatePermissions = true);
@@ -64,7 +66,7 @@ public function removeLabels($objectID, $validatePermissions = true);
      *
      * @param int[] $objectIDs
      * @param bool $validatePermissions
-     * @return  Label[][]
+     * @return Label[][]
      */
     public function getAssignedLabels(array $objectIDs, $validatePermissions = true);
 }
diff --git a/wcfsetup/install/files/lib/system/label/object/type/ArticleCategoryLabelObjectTypeHandler.class.php b/wcfsetup/install/files/lib/system/label/object/type/ArticleCategoryLabelObjectTypeHandler.class.php
index cac989ba90b..794ac94bd10 100644
--- a/wcfsetup/install/files/lib/system/label/object/type/ArticleCategoryLabelObjectTypeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/type/ArticleCategoryLabelObjectTypeHandler.class.php
@@ -4,6 +4,7 @@
 
 use wcf\data\article\category\ArticleCategoryNode;
 use wcf\data\article\category\ArticleCategoryNodeTree;
+use wcf\data\category\CategoryNode;
 use wcf\system\cache\builder\ArticleCategoryLabelCacheBuilder;
 
 /**
@@ -18,7 +19,7 @@ class ArticleCategoryLabelObjectTypeHandler extends AbstractLabelObjectTypeHandl
 {
     /**
      * category list
-     * @var \RecursiveIteratorIterator
+     * @var \RecursiveIteratorIterator<CategoryNode>
      */
     public $categoryList;
 
diff --git a/wcfsetup/install/files/lib/system/label/object/type/ILabelObjectTypeHandler.class.php b/wcfsetup/install/files/lib/system/label/object/type/ILabelObjectTypeHandler.class.php
index fdb81d67a61..7fc04855d81 100644
--- a/wcfsetup/install/files/lib/system/label/object/type/ILabelObjectTypeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/type/ILabelObjectTypeHandler.class.php
@@ -15,6 +15,7 @@ interface ILabelObjectTypeHandler
      * Sets object type id.
      *
      * @param int $objectTypeID
+     * @return void
      */
     public function setObjectTypeID($objectTypeID);
 
@@ -34,6 +35,8 @@ public function getContainer();
 
     /**
      * Performs save actions.
+     *
+     * @return void
      */
     public function save();
 }
diff --git a/wcfsetup/install/files/lib/system/label/object/type/LabelObjectType.class.php b/wcfsetup/install/files/lib/system/label/object/type/LabelObjectType.class.php
index 073ec90737c..825e30113b2 100644
--- a/wcfsetup/install/files/lib/system/label/object/type/LabelObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/type/LabelObjectType.class.php
@@ -100,6 +100,7 @@ public function getDepth()
      * Sets option value.
      *
      * @param int $optionValue
+     * @return void
      */
     public function setOptionValue($optionValue)
     {
diff --git a/wcfsetup/install/files/lib/system/label/object/type/LabelObjectTypeContainer.class.php b/wcfsetup/install/files/lib/system/label/object/type/LabelObjectTypeContainer.class.php
index b095d723027..76cf08e8b56 100644
--- a/wcfsetup/install/files/lib/system/label/object/type/LabelObjectTypeContainer.class.php
+++ b/wcfsetup/install/files/lib/system/label/object/type/LabelObjectTypeContainer.class.php
@@ -10,6 +10,7 @@
  * @author Alexander Ebert
  * @copyright 2001-2022 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements \Iterator<int, LabelObjectType>
  */
 final class LabelObjectTypeContainer implements \Countable, \Iterator
 {
diff --git a/wcfsetup/install/files/lib/system/language/I18nHandler.class.php b/wcfsetup/install/files/lib/system/language/I18nHandler.class.php
index f95f65fc3a1..0ed7e205ce3 100644
--- a/wcfsetup/install/files/lib/system/language/I18nHandler.class.php
+++ b/wcfsetup/install/files/lib/system/language/I18nHandler.class.php
@@ -98,7 +98,8 @@ public function unregister(string $elementID): void
     /**
      * Reads plain and i18n values from request data.
      *
-     * @param $requestData used request data (if `null`, `$_POST` is used)
+     * @param mixed[] $requestData used request data (if `null`, `$_POST` is used)
+     * @return void
      * @throws  SystemException
      */
     public function readValues(?array $requestData = null): void
@@ -269,6 +270,7 @@ public function validateValue(string $elementID, bool $requireI18n = false, bool
      * Saves language variable for i18n.
      *
      * @param string|string[] $elementID either the id of the element or externally passed array `languageID => value`
+     * @return void
      */
     public function save($elementID, string $languageVariable, string $languageCategory, int $packageID = PACKAGE_ID)
     {
diff --git a/wcfsetup/install/files/lib/system/language/I18nValue.class.php b/wcfsetup/install/files/lib/system/language/I18nValue.class.php
index a64342c46ef..cfa9e3ed0a9 100644
--- a/wcfsetup/install/files/lib/system/language/I18nValue.class.php
+++ b/wcfsetup/install/files/lib/system/language/I18nValue.class.php
@@ -70,6 +70,7 @@ public function __construct($fieldName)
      * @param string $item
      * @param string $category
      * @param string $package
+     * @return void
      */
     public function setLanguageItem($item, $category, $package)
     {
@@ -82,6 +83,7 @@ public function setLanguageItem($item, $category, $package)
      * Sets bit flags.
      *
      * @param int $flags
+     * @return void
      */
     public function setFlags($flags)
     {
diff --git a/wcfsetup/install/files/lib/system/language/LanguageFactory.class.php b/wcfsetup/install/files/lib/system/language/LanguageFactory.class.php
index 3ab54d2806b..96c9d46bbf5 100644
--- a/wcfsetup/install/files/lib/system/language/LanguageFactory.class.php
+++ b/wcfsetup/install/files/lib/system/language/LanguageFactory.class.php
@@ -18,12 +18,13 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type LanguageCache from LanguageCacheBuilder
  */
 class LanguageFactory extends SingletonFactory
 {
     /**
      * language cache
-     * @var mixed[]
+     * @var LanguageCache
      */
     protected $cache;
 
@@ -51,7 +52,7 @@ protected function init()
      * Returns a Language object for the language with the given id.
      *
      * @param int $languageID
-     * @return  Language|null
+     * @return ?Language
      */
     public function getLanguage($languageID)
     {
@@ -70,7 +71,7 @@ public function getLanguage($languageID)
      * Returns the preferred language of the current user.
      *
      * @param int $languageID
-     * @return  Language
+     * @return ?Language
      */
     public function getUserLanguage($languageID = 0)
     {
@@ -117,7 +118,7 @@ public function getLanguageByCode($languageCode)
      * Returns true if the language category with the given name exists.
      *
      * @param string $categoryName
-     * @return  bool
+     * @return bool
      */
     public function isValidCategory($categoryName)
     {
@@ -128,7 +129,7 @@ public function isValidCategory($categoryName)
      * Returns the language category with the given name.
      *
      * @param string $categoryName
-     * @return  LanguageCategory|null
+     * @return ?LanguageCategory
      */
     public function getCategory($categoryName)
     {
@@ -139,7 +140,7 @@ public function getCategory($categoryName)
      * Returns language category by id.
      *
      * @param int $languageCategoryID
-     * @return  LanguageCategory|null
+     * @return ?LanguageCategory
      */
     public function getCategoryByID($languageCategoryID)
     {
@@ -153,7 +154,7 @@ public function getCategoryByID($languageCategoryID)
     /**
      * Returns a list of available language categories.
      *
-     * @return  LanguageCategory[]
+     * @return LanguageCategory[]
      */
     public function getCategories()
     {
@@ -162,6 +163,8 @@ public function getCategories()
 
     /**
      * Searches the preferred language of the current user.
+     *
+     * @return int
      */
     protected function findPreferredLanguage()
     {
@@ -171,24 +174,24 @@ protected function findPreferredLanguage()
             $availableLanguageCodes[] = $language->languageCode;
         }
 
-        // get default language
         $defaultLanguageCode = $this->cache['languages'][$this->cache['default']]->languageCode;
-
-        // get preferred language
         $languageCode = self::getPreferredLanguage($availableLanguageCodes, $defaultLanguageCode);
 
         // get language id of preferred language
         foreach ($this->cache['languages'] as $key => $language) {
-            if ($language->languageCode == $languageCode) {
+            if ($language->languageCode === $languageCode) {
                 return $key;
             }
         }
+
+        return 0;
     }
 
     /**
      * Determines the preferred language of the current user.
      *
      * @param string[] $availableLanguageCodes
+     * @return string
      */
     public static function getPreferredLanguage(array $availableLanguageCodes, string $defaultLanguageCode): string
     {
@@ -216,7 +219,7 @@ public static function getPreferredLanguage(array $availableLanguageCodes, strin
     /**
      * Returns the active scripting compiler object.
      *
-     * @return  TemplateScriptingCompiler
+     * @return TemplateScriptingCompiler
      */
     public function getScriptingCompiler()
     {
@@ -229,6 +232,8 @@ public function getScriptingCompiler()
 
     /**
      * Loads the language cache.
+     *
+     * @return void
      */
     protected function loadCache()
     {
@@ -237,6 +242,8 @@ protected function loadCache()
 
     /**
      * Clears languages cache.
+     *
+     * @return void
      */
     public function clearCache()
     {
@@ -248,7 +255,7 @@ public function clearCache()
      * Converts e.g. 'de-informal' to 'de'.
      *
      * @param string $languageCode
-     * @return  string      $languageCode
+     * @return string $languageCode
      */
     public static function fixLanguageCode($languageCode)
     {
@@ -258,8 +265,8 @@ public static function fixLanguageCode($languageCode)
     /**
      * Returns the default language object.
      *
-     * @return  Language
-     * @since   3.0
+     * @return Language
+     * @since 3.0
      */
     public function getDefaultLanguage()
     {
@@ -269,7 +276,7 @@ public function getDefaultLanguage()
     /**
      * Returns the default language id
      *
-     * @return  int
+     * @return int
      */
     public function getDefaultLanguageID()
     {
@@ -279,7 +286,7 @@ public function getDefaultLanguageID()
     /**
      * Returns all available languages.
      *
-     * @return  Language[]
+     * @return Language[]
      */
     public function getLanguages()
     {
@@ -289,7 +296,7 @@ public function getLanguages()
     /**
      * Returns all available content languages for given package.
      *
-     * @return  Language[]
+     * @return array<int, Language>
      */
     public function getContentLanguages()
     {
@@ -306,8 +313,8 @@ public function getContentLanguages()
     /**
      * Returns the list of content language ids.
      *
-     * @return      int[]
-     * @since       3.1
+     * @return int[]
+     * @since 3.1
      */
     public function getContentLanguageIDs()
     {
@@ -325,6 +332,7 @@ public function getContentLanguageIDs()
      * Makes given language the default language.
      *
      * @param int $languageID
+     * @return void
      */
     public function makeDefault($languageID)
     {
@@ -348,6 +356,8 @@ public function makeDefault($languageID)
 
     /**
      * Removes language cache and compiled templates.
+     *
+     * @return void
      */
     public function deleteLanguageCache()
     {
@@ -362,7 +372,7 @@ public function deleteLanguageCache()
     /**
      * Returns true if multilingualism is enabled.
      *
-     * @return  bool
+     * @return bool
      */
     public function multilingualismEnabled()
     {
@@ -372,7 +382,7 @@ public function multilingualismEnabled()
     /**
      * Returns the number of phrases that have been automatically disabled in the past 7 days.
      *
-     * @return      int
+     * @return int
      */
     public function countRecentlyDisabledCustomValues()
     {
diff --git a/wcfsetup/install/files/lib/system/like/IViewableLikeProvider.class.php b/wcfsetup/install/files/lib/system/like/IViewableLikeProvider.class.php
index 67ed6dab542..6f2771b4bb1 100644
--- a/wcfsetup/install/files/lib/system/like/IViewableLikeProvider.class.php
+++ b/wcfsetup/install/files/lib/system/like/IViewableLikeProvider.class.php
@@ -17,6 +17,7 @@ interface IViewableLikeProvider
      * Prepares a list of likes for output.
      *
      * @param ViewableLike[] $likes
+     * @return void
      */
     public function prepare(array $likes);
 }
diff --git a/wcfsetup/install/files/lib/system/like/LikeHandler.class.php b/wcfsetup/install/files/lib/system/like/LikeHandler.class.php
index d839d90c7be..3653787e265 100644
--- a/wcfsetup/install/files/lib/system/like/LikeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/like/LikeHandler.class.php
@@ -26,6 +26,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @deprecated  The LikeHandler is deprecated since 5.2 in favor of the \wcf\system\reaction\ReactionHandler
+ * @phpstan-type LikeStatus array{likes: int, dislikes: int, cumulativeLikes: int, liked: int}
  */
 class LikeHandler extends SingletonFactory
 {
@@ -88,7 +89,7 @@ public function getLikeObjects(ObjectType $objectType)
      * like objects
      *
      * @param ObjectType $objectType
-     * @param array $objectIDs
+     * @param int[] $objectIDs
      * @return  int
      */
     public function loadLikeObjects(ObjectType $objectType, array $objectIDs)
@@ -103,7 +104,13 @@ public function loadLikeObjects(ObjectType $objectType, array $objectIDs)
      * @param User $user
      * @param int $likeValue
      * @param int $time
-     * @return  array
+     * @return array{
+     *  data: LikeStatus|array{},
+     *  like: Like|null|0,
+     *  newValue: 0,
+     *  oldValue: 0,
+     *  users: array{}
+     * }
      */
     public function like(ILikeObject $likeable, User $user, $likeValue, $time = TIME_NOW)
     {
@@ -140,7 +147,13 @@ public function like(ILikeObject $likeable, User $user, $likeValue, $time = TIME
      * @param ILikeObject $likeable
      * @param LikeObject $likeObject
      * @param User $user
-     * @return  array
+     * @return array{
+     *  data: LikeStatus,
+     *  like: null,
+     *  newValue: 0,
+     *  oldValue: 0,
+     *  users: array{}
+     * }
      */
     public function revertLike(Like $like, ILikeObject $likeable, LikeObject $likeObject, User $user)
     {
@@ -161,6 +174,7 @@ public function revertLike(Like $like, ILikeObject $likeable, LikeObject $likeOb
      * @param string $objectType
      * @param int[] $objectIDs
      * @param string[] $notificationObjectTypes
+     * @return void
      */
     public function removeLikes($objectType, array $objectIDs, array $notificationObjectTypes = [])
     {
@@ -172,7 +186,7 @@ public function removeLikes($objectType, array $objectIDs, array $notificationOb
      *
      * @param LikeObject $likeObject
      * @param User $user
-     * @return  array
+     * @return LikeStatus
      */
     protected function loadLikeStatus(LikeObject $likeObject, User $user)
     {
diff --git a/wcfsetup/install/files/lib/system/log/modification/AbstractModificationLogHandler.class.php b/wcfsetup/install/files/lib/system/log/modification/AbstractModificationLogHandler.class.php
index 4d50b64bbfc..8eda849f1f8 100644
--- a/wcfsetup/install/files/lib/system/log/modification/AbstractModificationLogHandler.class.php
+++ b/wcfsetup/install/files/lib/system/log/modification/AbstractModificationLogHandler.class.php
@@ -52,12 +52,12 @@ protected function init()
      * @param string $action
      * @param int $objectID
      * @param int|null $parentObjectID
-     * @param array $additionalData
+     * @param mixed[] $additionalData
      * @param int $time
      * @param int|null $userID
      * @param string|null $username
      * @param int $hidden
-     * @return  ModificationLog
+     * @return ModificationLog
      */
     public function createLog(
         $action,
@@ -107,6 +107,7 @@ public function createLog(
      *
      * @param int[] $objectIDs
      * @param string[] $ignoredActions names of actions whose log entries will not be deleted
+     * @return void
      */
     public function deleteLogs(array $objectIDs, array $ignoredActions = [])
     {
@@ -131,6 +132,7 @@ public function deleteLogs(array $objectIDs, array $ignoredActions = [])
      * Deletes modification log entries by the id of the parent object.
      *
      * @param int[] $parentObjectIDs
+     * @return void
      */
     public function deleteLogsByParentIDs(array $parentObjectIDs)
     {
@@ -170,6 +172,7 @@ public function getObjectType($objectType = null)
      *
      * @param int[] $objectIDs
      * @param int $newParentObjectID
+     * @return void
      */
     public function updateParentObjectID(array $objectIDs, $newParentObjectID)
     {
diff --git a/wcfsetup/install/files/lib/system/menu/TreeMenu.class.php b/wcfsetup/install/files/lib/system/menu/TreeMenu.class.php
index db366347e01..53181a25a41 100644
--- a/wcfsetup/install/files/lib/system/menu/TreeMenu.class.php
+++ b/wcfsetup/install/files/lib/system/menu/TreeMenu.class.php
@@ -29,7 +29,7 @@ abstract class TreeMenu extends SingletonFactory
 
     /**
      * list of all menu items
-     * @var ITreeMenuItem[][]
+     * @var array<string, ITreeMenuItem[]>
      */
     public $menuItems;
 
@@ -56,6 +56,8 @@ protected function init()
 
     /**
      * Loads cached menu items.
+     *
+     * @return void
      */
     protected function loadCache()
     {
@@ -69,7 +71,7 @@ protected function loadCache()
      * Checks the options and permissions of given menu item.
      *
      * @param ITreeMenuItem $item
-     * @return  bool
+     * @return bool
      */
     protected function checkMenuItem(ITreeMenuItem $item)
     {
@@ -112,6 +114,7 @@ protected function checkMenuItem(ITreeMenuItem $item)
      * Checks the options and permissions of the menu items.
      *
      * @param string $parentMenuItem
+     * @return void
      */
     protected function checkMenuItems($parentMenuItem = '')
     {
@@ -134,6 +137,7 @@ protected function checkMenuItems($parentMenuItem = '')
      * Removes items without children.
      *
      * @param string $parentMenuItem
+     * @return void
      */
     protected function removeEmptyItems($parentMenuItem = '')
     {
@@ -158,6 +162,7 @@ protected function removeEmptyItems($parentMenuItem = '')
      * Builds a plain menu item list.
      *
      * @param string $parentMenuItem
+     * @return void
      */
     protected function buildMenuItemList($parentMenuItem = '')
     {
@@ -178,6 +183,7 @@ protected function buildMenuItemList($parentMenuItem = '')
      * This function should be used in each script which uses a template that includes the menu.tpl.
      *
      * @param string $menuItem name of the active menu item
+     * @return void
      */
     public function setActiveMenuItem($menuItem)
     {
@@ -199,7 +205,7 @@ public function setActiveMenuItem($menuItem)
     /**
      * Returns a list of the active menu items.
      *
-     * @return  array
+     * @return string[]
      */
     public function getActiveMenuItems()
     {
@@ -210,7 +216,7 @@ public function getActiveMenuItems()
      * Returns the active menu item.
      *
      * @param int $level
-     * @return  string|null
+     * @return ?string
      */
     public function getActiveMenuItem($level = 0)
     {
@@ -225,7 +231,7 @@ public function getActiveMenuItem($level = 0)
      * Returns the list of menu items.
      *
      * @param string $parentMenuItem
-     * @return  array
+     * @return ITreeMenuItem[]|array<string, ITreeMenuItem[]>
      */
     public function getMenuItems($parentMenuItem = null)
     {
diff --git a/wcfsetup/install/files/lib/system/menu/user/DefaultUserMenuItemProvider.class.php b/wcfsetup/install/files/lib/system/menu/user/DefaultUserMenuItemProvider.class.php
index 7d575f4191e..d1b26f360c1 100644
--- a/wcfsetup/install/files/lib/system/menu/user/DefaultUserMenuItemProvider.class.php
+++ b/wcfsetup/install/files/lib/system/menu/user/DefaultUserMenuItemProvider.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserMenuItem    getDecoratedObject()
  * @mixin   UserMenuItem
+ * @extends DatabaseObjectDecorator<UserMenuItem>
  */
 class DefaultUserMenuItemProvider extends DatabaseObjectDecorator implements IUserMenuItemProvider
 {
diff --git a/wcfsetup/install/files/lib/system/menu/user/UserMenu.class.php b/wcfsetup/install/files/lib/system/menu/user/UserMenu.class.php
index bcd2d2cc450..2e9c166be93 100644
--- a/wcfsetup/install/files/lib/system/menu/user/UserMenu.class.php
+++ b/wcfsetup/install/files/lib/system/menu/user/UserMenu.class.php
@@ -61,6 +61,11 @@ protected function checkMenuItem(ITreeMenuItem $item)
     }
 
     /**
+     * @return list<array{
+     *  category: UserMenuItem,
+     *  items: list<string>,
+     *  link: string,
+     * }>
      * @since 5.5
      */
     public function getUserMenuItems(): array
diff --git a/wcfsetup/install/files/lib/system/menu/user/profile/UserProfileMenu.class.php b/wcfsetup/install/files/lib/system/menu/user/profile/UserProfileMenu.class.php
index e9ae6611822..8ed775625f8 100644
--- a/wcfsetup/install/files/lib/system/menu/user/profile/UserProfileMenu.class.php
+++ b/wcfsetup/install/files/lib/system/menu/user/profile/UserProfileMenu.class.php
@@ -45,6 +45,8 @@ protected function init()
 
     /**
      * Loads cached menu items.
+     *
+     * @return void
      */
     protected function loadCache()
     {
@@ -56,6 +58,8 @@ protected function loadCache()
 
     /**
      * Checks the options and permissions of the menu items.
+     *
+     * @return void
      */
     protected function checkMenuItems()
     {
diff --git a/wcfsetup/install/files/lib/system/message/QuickReplyManager.class.php b/wcfsetup/install/files/lib/system/message/QuickReplyManager.class.php
index ae715a8a62f..1842e9410e1 100644
--- a/wcfsetup/install/files/lib/system/message/QuickReplyManager.class.php
+++ b/wcfsetup/install/files/lib/system/message/QuickReplyManager.class.php
@@ -3,7 +3,10 @@
 namespace wcf\system\message;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectDecorator;
+use wcf\data\DatabaseObjectEditor;
+use wcf\data\DatabaseObjectList;
 use wcf\data\IAttachmentMessageQuickReplyAction;
 use wcf\data\IMessage;
 use wcf\data\IMessageQuickReplyAction;
@@ -51,7 +54,7 @@ class QuickReplyManager extends SingletonFactory
      *
      * @param string $type
      * @param int $objectID
-     * @return  string
+     * @return string
      */
     public function getMessage($type, $objectID)
     {
@@ -72,6 +75,7 @@ public function getMessage($type, $objectID)
      * @param string $type
      * @param int $objectID
      * @param string $message
+     * @return void
      */
     public function setMessage($type, $objectID, $message)
     {
@@ -83,6 +87,7 @@ public function setMessage($type, $objectID, $message)
      *
      * @param string $type
      * @param int $objectID
+     * @return void
      */
     public function removeMessage($type, $objectID)
     {
@@ -93,6 +98,7 @@ public function removeMessage($type, $objectID)
      * Sets the disallowed bbcodes.
      *
      * @param string[] $disallowedBBCodes
+     * @return void
      */
     public function setDisallowedBBCodes(array $disallowedBBCodes)
     {
@@ -102,12 +108,13 @@ public function setDisallowedBBCodes(array $disallowedBBCodes)
     /**
      * Validates parameters for current request.
      *
-     * @param IMessageQuickReplyAction $object
+     * @param IMessageQuickReplyAction<DatabaseObject, DatabaseObject, DatabaseObjectList<DatabaseObject>> $object
      * @param mixed[] $parameters
      * @param string $containerClassName
      * @param string $containerDecoratorClassName
-     * @throws  ParentClassException
-     * @throws  UserInputException
+     * @return void
+     * @throws ParentClassException
+     * @throws UserInputException
      */
     public function validateParameters(
         IMessageQuickReplyAction $object,
@@ -200,14 +207,23 @@ public function validateParameters(
     /**
      * Creates a new message and returns the parsed template.
      *
-     * @param IMessageQuickReplyAction $object
-     * @param array $parameters
-     * @param class-string<AbstractDatabaseObjectAction> $containerActionClassName
+     * @param IMessageQuickReplyAction<DatabaseObject, DatabaseObject, DatabaseObjectList<DatabaseObject>> $object
+     * @param mixed[] $parameters
+     * @param class-string<AbstractDatabaseObjectAction<DatabaseObject, DatabaseObjectEditor<DatabaseObject>>> $containerActionClassName
      * @param string $sortOrder
      * @param string $templateName
      * @param string $application
      * @param callable $callbackCreatedMessage
-     * @return  array
+     * @return array{
+     *  isVisible: false
+     * }|array{
+     *  lastPostTime: int,
+     *  objectID: int,
+     *  template: string,
+     * }|array{
+     *  objectID: int,
+     *  url: string,
+     * }
      */
     public function createMessage(
         IMessageQuickReplyAction $object,
@@ -311,6 +327,8 @@ public function getContainer()
     }
 
     /**
+     * @param string $tmpHash
+     * @return void
      * @deprecated 5.5 The concept of starting a message in a simple editor and then migrating to an extended editor no longer exists.
      */
     public function setTmpHash($tmpHash)
diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/AbstractMessageEmbeddedObjectHandler.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/AbstractMessageEmbeddedObjectHandler.class.php
index 182048dda3a..cf33f7b1733 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/AbstractMessageEmbeddedObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/AbstractMessageEmbeddedObjectHandler.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  ObjectType  getDecoratedObject()
  * @mixin   ObjectType
+ * @extends DatabaseObjectDecorator<ObjectType>
  */
 abstract class AbstractMessageEmbeddedObjectHandler extends DatabaseObjectDecorator implements
     IMessageEmbeddedObjectHandler
diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/IMessageEmbeddedObjectHandler.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/IMessageEmbeddedObjectHandler.class.php
index 6bd0c0ea046..668e6bae719 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/IMessageEmbeddedObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/IMessageEmbeddedObjectHandler.class.php
@@ -23,15 +23,15 @@ interface IMessageEmbeddedObjectHandler
      *
      * @param HtmlInputProcessor $htmlInputProcessor html input processor holding the current document
      * @param mixed[] $embeddedData list of found embedded data with attributes
-     * @return      int[]               ids of found embedded objects
+     * @return int[] ids of found embedded objects
      */
     public function parse(HtmlInputProcessor $htmlInputProcessor, array $embeddedData);
 
     /**
      * Loads and returns embedded objects.
      *
-     * @param array $objectIDs
-     * @return  DatabaseObject[]
+     * @param int[] $objectIDs
+     * @return DatabaseObject[]
      */
     public function loadObjects(array $objectIDs);
 }
diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/ISimpleMessageEmbeddedObjectHandler.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/ISimpleMessageEmbeddedObjectHandler.class.php
index 887ca5638b7..e61fbb2b864 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/ISimpleMessageEmbeddedObjectHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/ISimpleMessageEmbeddedObjectHandler.class.php
@@ -17,7 +17,7 @@ interface ISimpleMessageEmbeddedObjectHandler extends IMessageEmbeddedObjectHand
      * @param string $objectType object type identifier
      * @param int $objectID object id
      * @param int[] $values list of value ids
-     * @return      int[]       filtered list
+     * @return int[] filtered list
      */
     public function validateValues($objectType, $objectID, array $values);
 
@@ -27,9 +27,9 @@ public function validateValues($objectType, $objectID, array $values);
      *
      * @param string $objectType object type identifier
      * @param int $objectID object id
-     * @param int $value value id
-     * @param array $attributes list of additional attributes
-     * @return      string|null     replacement string or null if value id is unknown
+     * @param string|int $value value id
+     * @param array<string, string> $attributes list of additional attributes
+     * @return ?string replacement string or null if value id is unknown
      */
     public function replaceSimple($objectType, $objectID, $value, array $attributes);
 }
diff --git a/wcfsetup/install/files/lib/system/message/embedded/object/MessageEmbeddedObjectManager.class.php b/wcfsetup/install/files/lib/system/message/embedded/object/MessageEmbeddedObjectManager.class.php
index ebb3cc56ca8..a66587af1fd 100644
--- a/wcfsetup/install/files/lib/system/message/embedded/object/MessageEmbeddedObjectManager.class.php
+++ b/wcfsetup/install/files/lib/system/message/embedded/object/MessageEmbeddedObjectManager.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\message\embedded\object;
 
+use wcf\data\DatabaseObject;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\exception\InvalidObjectTypeException;
@@ -20,13 +21,13 @@ class MessageEmbeddedObjectManager extends SingletonFactory
 {
     /**
      * caches message to embedded object assignments
-     * @var array
+     * @var array<int, array<int, array<int, int[]>>>
      */
     protected $messageEmbeddedObjects = [];
 
     /**
      * caches embedded objects
-     * @var array
+     * @var array<int, array<int, DatabaseObject>>
      */
     protected $embeddedObjects = [];
 
@@ -50,7 +51,7 @@ class MessageEmbeddedObjectManager extends SingletonFactory
 
     /**
      * list of embedded object handlers
-     * @var array
+     * @var array<int, IMessageEmbeddedObjectHandler>
      */
     protected $embeddedObjectHandlers;
 
@@ -62,7 +63,10 @@ class MessageEmbeddedObjectManager extends SingletonFactory
 
     /**
      * local cache for bulk operations
-     * @var mixed[][]
+     * @var array{
+     *  insert: list<array{0: int, 1: int, 2: int, 3: int}>,
+     *  remove: array<string, int[]>,
+     * }
      */
     protected $bulkData = [
         'insert' => [],
@@ -72,6 +76,12 @@ class MessageEmbeddedObjectManager extends SingletonFactory
     /**
      * A list of previous active message settings used to restore
      * the internal state in case of nested message processing.
+     *
+     * @var list<array{
+     *  activeMessageID: int,
+     *  activeMessageLanguageID: int,
+     *  activeMessageObjectTypeID: int,
+     * }>
      */
     protected $activeMessageHistory = [];
 
@@ -143,6 +153,8 @@ public function registerObjects(HtmlInputProcessor $htmlInputProcessor, $isBulk
     /**
      * Commits the bulk operation by performing all deletes and inserts
      * in one big transaction to save performance.
+     *
+     * @return void
      */
     public function commitBulkOperation()
     {
@@ -215,6 +227,7 @@ public function registerSimpleObjects($messageObjectType, $messageID, array $emb
      *
      * @param string $messageObjectType
      * @param int[] $messageIDs
+     * @return void
      */
     public function removeObjects($messageObjectType, array $messageIDs)
     {
@@ -237,6 +250,7 @@ public function removeObjects($messageObjectType, array $messageIDs)
      * @param string $messageObjectType
      * @param int[] $messageIDs
      * @param int $contentLanguageID
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function loadObjects($messageObjectType, array $messageIDs, $contentLanguageID = null)
@@ -305,6 +319,7 @@ public function getContentLanguageID()
      * @param string $messageObjectType
      * @param int $messageID
      * @param int $languageID
+     * @return void
      */
     public function setActiveMessage($messageObjectType, $messageID, $languageID = null)
     {
@@ -324,6 +339,8 @@ public function setActiveMessage($messageObjectType, $messageID, $languageID = n
 
     /**
      * Restores the internal state in case of nested message processing.
+     *
+     * @return void
      */
     public function reset()
     {
@@ -375,7 +392,7 @@ public function getActiveMessageID(): ?int
      * Returns all embedded objects of a specific type in the active message.
      *
      * @param string $embeddedObjectType
-     * @return  array
+     * @return list<DatabaseObject>
      */
     public function getObjects($embeddedObjectType)
     {
@@ -396,6 +413,7 @@ public function getObjects($embeddedObjectType)
     /**
      * Returns all embedded objects in a specific message.
      *
+     * @return list<DatabaseObject>
      * @since 6.2
      */
     public function getObjectsForMessage(string $messageObjectType, int $messageID): array
@@ -422,7 +440,7 @@ public function getObjectsForMessage(string $messageObjectType, int $messageID):
      *
      * @param string $embeddedObjectType
      * @param int $objectID
-     * @return  \wcf\data\DatabaseObject|null
+     * @return ?DatabaseObject
      */
     public function getObject($embeddedObjectType, $objectID)
     {
@@ -456,6 +474,7 @@ public function getObject($embeddedObjectType, $objectID)
      * Temporarily registers a message, the parsed data will not be stored.
      *
      * @param HtmlInputProcessor $htmlInputProcessor html input processor
+     * @return void
      */
     public function registerTemporaryMessage(HtmlInputProcessor $htmlInputProcessor)
     {
@@ -467,7 +486,6 @@ public function registerTemporaryMessage(HtmlInputProcessor $htmlInputProcessor)
 
         $embeddedData = $htmlInputProcessor->getEmbeddedContent();
 
-        /** @var IMessageEmbeddedObjectHandler $handler */
         foreach ($this->getEmbeddedObjectHandlers() as $handler) {
             $objectIDs = $handler->parse($htmlInputProcessor, $embeddedData);
 
@@ -482,7 +500,7 @@ public function registerTemporaryMessage(HtmlInputProcessor $htmlInputProcessor)
     }
 
     /**
-     * @return ISimpleMessageEmbeddedObjectHandler[]
+     * @return array<string, ISimpleMessageEmbeddedObjectHandler>
      */
     public function getSimpleMessageEmbeddedObjectHandlers()
     {
diff --git a/wcfsetup/install/files/lib/system/message/quote/AbstractMessageQuoteHandler.class.php b/wcfsetup/install/files/lib/system/message/quote/AbstractMessageQuoteHandler.class.php
index 3326a79a608..05b5cc78299 100644
--- a/wcfsetup/install/files/lib/system/message/quote/AbstractMessageQuoteHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/quote/AbstractMessageQuoteHandler.class.php
@@ -59,6 +59,7 @@ public function render(array $data, $supportPaste = false)
 
     /**
      * @inheritDoc
+     * @param bool $renderAsString
      */
     public function renderQuotes(array $data, $render = true, $renderAsString = true)
     {
@@ -92,6 +93,7 @@ public function renderQuotes(array $data, $render = true, $renderAsString = true
      * Overrides the full quote flag for given message.
      *
      * @param QuotedMessage[] $messages
+     * @return void
      */
     protected function overrideIsFullQuote(array $messages)
     {
diff --git a/wcfsetup/install/files/lib/system/message/quote/IMessageQuoteHandler.class.php b/wcfsetup/install/files/lib/system/message/quote/IMessageQuoteHandler.class.php
index c86d11b0370..8b6543815f7 100644
--- a/wcfsetup/install/files/lib/system/message/quote/IMessageQuoteHandler.class.php
+++ b/wcfsetup/install/files/lib/system/message/quote/IMessageQuoteHandler.class.php
@@ -16,9 +16,9 @@ interface IMessageQuoteHandler
     /**
      * Renders a template for given quotes.
      *
-     * @param array $data
+     * @param mixed[][] $data
      * @param bool $supportPaste
-     * @return  string
+     * @return string
      */
     public function render(array $data, $supportPaste = false);
 
diff --git a/wcfsetup/install/files/lib/system/message/quote/MessageQuoteManager.class.php b/wcfsetup/install/files/lib/system/message/quote/MessageQuoteManager.class.php
index c6a7dea027b..f2243395d88 100644
--- a/wcfsetup/install/files/lib/system/message/quote/MessageQuoteManager.class.php
+++ b/wcfsetup/install/files/lib/system/message/quote/MessageQuoteManager.class.php
@@ -211,8 +211,7 @@ public function markQuotesForRemoval(array $quoteIDs): void
      * @param IMessage $message
      * @param string $text
      * @param bool $renderAsString
-     *
-     * @return  array|string
+     * @return array{username: string, link: string, text: string}|string
      * @deprecated 6.2
      */
     public function renderQuote(IMessage $message, $text, $renderAsString = true)
@@ -240,6 +239,7 @@ public function renderQuote(IMessage $message, $text, $renderAsString = true)
     /**
      * Removes quotes marked for removal.
      *
+     * @return void
      * @deprecated 6.2
      */
     public function removeMarkedQuotes()
@@ -275,7 +275,7 @@ public function getFullQuoteObjectIDs(array $objectTypes)
      *
      * @param string $objectType
      * @param int[] $objectIDs
-     *
+     * @return void
      * @deprecated 6.2
      */
     public function initObjects($objectType, array $objectIDs)
@@ -285,6 +285,7 @@ public function initObjects($objectType, array $objectIDs)
     /**
      * Reads the quote message id.
      *
+     * @return void
      * @deprecated 6.2
      */
     public function readParameters()
@@ -327,6 +328,7 @@ public function saved(): void
     /**
      * Assigns variables on page load.
      *
+     * @return void
      * @deprecated 6.2
      */
     public function assignVariables()
@@ -348,7 +350,7 @@ public function getQuoteMessageID()
      * Removes orphaned quote ids
      *
      * @param int[] $quoteIDs
-     *
+     * @return void
      * @deprecated 6.2
      */
     public function removeOrphanedQuotes(array $quoteIDs)
diff --git a/wcfsetup/install/files/lib/system/message/quote/QuotedMessage.class.php b/wcfsetup/install/files/lib/system/message/quote/QuotedMessage.class.php
index d2146b2bc29..31a33ad38b2 100644
--- a/wcfsetup/install/files/lib/system/message/quote/QuotedMessage.class.php
+++ b/wcfsetup/install/files/lib/system/message/quote/QuotedMessage.class.php
@@ -21,6 +21,7 @@
  * @method  int     getUserID()
  * @method  string      getUsername()
  * @method  bool        isVisible()
+ * @implements \Iterator<string>
  *
  * @deprecated 6.2
  */
@@ -78,6 +79,7 @@ public function __construct(IMessage $object)
      * @param string $quoteID
      * @param string $quote
      * @param string $fullQuote
+     * @return void
      */
     public function addQuote($quoteID, $quote, $fullQuote)
     {
@@ -111,6 +113,7 @@ public function __call($name, $value)
      *
      * @param string $quoteID
      * @param bool $overrideIsFullQuote
+     * @return void
      */
     public function setOverrideIsFullQuote($quoteID, $overrideIsFullQuote)
     {
diff --git a/wcfsetup/install/files/lib/system/moderation/AbstractDeletedContentProvider.class.php b/wcfsetup/install/files/lib/system/moderation/AbstractDeletedContentProvider.class.php
index 10d32d380ab..8e08cf33b71 100644
--- a/wcfsetup/install/files/lib/system/moderation/AbstractDeletedContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/AbstractDeletedContentProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\moderation;
 
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\AbstractObjectTypeProcessor;
 
 /**
@@ -10,6 +11,9 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
+ * @implements IDeletedContentProvider<T>
  */
 abstract class AbstractDeletedContentProvider extends AbstractObjectTypeProcessor implements IDeletedContentProvider
 {
diff --git a/wcfsetup/install/files/lib/system/moderation/IDeletedContentProvider.class.php b/wcfsetup/install/files/lib/system/moderation/IDeletedContentProvider.class.php
index e1222698ec3..f28ba639622 100644
--- a/wcfsetup/install/files/lib/system/moderation/IDeletedContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/IDeletedContentProvider.class.php
@@ -2,33 +2,37 @@
 
 namespace wcf\system\moderation;
 
+use wcf\data\DatabaseObjectList;
+
 /**
  * Interface for deleted content provider.
  *
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
  */
 interface IDeletedContentProvider
 {
     /**
      * Returns a list of deleted content.
      *
-     * @return  \wcf\data\DatabaseObjectList
+     * @return T
      */
     public function getObjectList();
 
     /**
      * Returns the template name for the result output.
      *
-     * @return  string
+     * @return string
      */
     public function getTemplateName();
 
     /**
      * Returns the application of the result template.
      *
-     * @return  string
+     * @return string
      */
     public function getApplication();
 }
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/AbstractModerationQueueManager.class.php b/wcfsetup/install/files/lib/system/moderation/queue/AbstractModerationQueueManager.class.php
index ecbfcb12140..02a4ce27742 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/AbstractModerationQueueManager.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/AbstractModerationQueueManager.class.php
@@ -90,7 +90,8 @@ public function removeContent(ModerationQueue $queue, $message = '')
      * @param int $objectTypeID
      * @param int $objectID
      * @param int $containerID
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      */
     protected function addEntry($objectTypeID, $objectID, $containerID = 0, array $additionalData = [])
     {
@@ -145,7 +146,8 @@ protected function addEntry($objectTypeID, $objectID, $containerID = 0, array $a
      * @param int $objectTypeID
      * @param int[] $objectIDs
      * @param int[] $containerIDs format: `objectID => containerID`
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      */
     protected function addEntries($objectTypeID, array $objectIDs, array $containerIDs, array $additionalData = [])
     {
@@ -251,6 +253,7 @@ protected function addEntries($objectTypeID, array $objectIDs, array $containerI
      *
      * @param int $objectTypeID
      * @param int[] $objectIDs
+     * @return void
      */
     protected function removeEntries($objectTypeID, array $objectIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueHandler.class.php b/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueHandler.class.php
index 70f83ae238f..d1295b07a27 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueHandler.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueHandler.class.php
@@ -18,6 +18,7 @@ interface IModerationQueueHandler
      * Creates queue assignments for matching object ids.
      *
      * @param ModerationQueue[] $queues
+     * @return void
      */
     public function assignQueues(array $queues);
 
@@ -25,7 +26,7 @@ public function assignQueues(array $queues);
      * Returns the container id for current object id, may return 0.
      *
      * @param int $objectID
-     * @return  int
+     * @return int
      */
     public function getContainerID($objectID);
 
@@ -33,7 +34,7 @@ public function getContainerID($objectID);
      * Validates object ids and returns orphaned queue ids.
      *
      * @param int[] $queues
-     * @return  int[]
+     * @return int[]
      */
     public function identifyOrphans(array $queues);
 
@@ -41,7 +42,7 @@ public function identifyOrphans(array $queues);
      * Returns true if given object id is valid.
      *
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function isValid($objectID);
 
@@ -49,6 +50,7 @@ public function isValid($objectID);
      * Populates object properties for viewing.
      *
      * @param ViewableModerationQueue[] $queues
+     * @return void
      */
     public function populate(array $queues);
 
@@ -58,6 +60,7 @@ public function populate(array $queues);
      *
      * @param ModerationQueue $queue
      * @param string $message
+     * @return void
      */
     public function removeContent(ModerationQueue $queue, $message);
 
@@ -65,7 +68,7 @@ public function removeContent(ModerationQueue $queue, $message);
      * Returns true if the affected content may be removed.
      *
      * @param ModerationQueue $queue
-     * @return  bool
+     * @return bool
      */
     public function canRemoveContent(ModerationQueue $queue);
 
@@ -74,6 +77,7 @@ public function canRemoveContent(ModerationQueue $queue);
      * object is permanently deleted.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function removeQueues(array $objectIDs);
 
@@ -82,7 +86,7 @@ public function removeQueues(array $objectIDs);
      *
      * @param ModerationQueue $queue
      * @param int $userID
-     * @return  bool
+     * @return bool
      */
     public function isAffectedUser(ModerationQueue $queue, $userID);
 
@@ -90,8 +94,8 @@ public function isAffectedUser(ModerationQueue $queue, $userID);
      * Returns the prefix of language items for notifications for comments
      * and comment responses on moderation queues of this type.
      *
-     * @return  string
-     * @since   3.0
+     * @return string
+     * @since 3.0
      */
     public function getCommentNotificationLanguageItemPrefix();
 
@@ -99,8 +103,8 @@ public function getCommentNotificationLanguageItemPrefix();
      * Returns the language item for the type name for notifications for comments
      * and comment responses on moderation queues of this type.
      *
-     * @return  string
-     * @since   6.0
+     * @return string
+     * @since 6.0
      */
     public function getCommentNotificationTypeNameLanguageItem(): string;
 }
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueManager.class.php b/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueManager.class.php
index 77478aadb5e..79efc36de66 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueManager.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/IModerationQueueManager.class.php
@@ -19,6 +19,7 @@ interface IModerationQueueManager
      *
      * @param int $objectTypeID
      * @param ModerationQueue[] $queues
+     * @return void
      */
     public function assignQueues($objectTypeID, array $queues);
 
@@ -27,7 +28,7 @@ public function assignQueues($objectTypeID, array $queues);
      *
      * @param string $objectType
      * @param int $objectID
-     * @return  bool
+     * @return bool
      */
     public function isValid($objectType, $objectID = null);
 
@@ -35,7 +36,7 @@ public function isValid($objectType, $objectID = null);
      * Returns link for viewing/editing objects for this moderation type.
      *
      * @param int $queueID
-     * @return  string
+     * @return string
      */
     public function getLink($queueID);
 
@@ -43,7 +44,7 @@ public function getLink($queueID);
      * Returns object type id for given object type.
      *
      * @param string $objectType
-     * @return  int
+     * @return int
      */
     public function getObjectTypeID($objectType);
 
@@ -61,6 +62,7 @@ public function getProcessor($objectType, $objectTypeID = null);
      *
      * @param int $objectTypeID
      * @param ViewableModerationQueue[] $objects
+     * @return void
      */
     public function populate($objectTypeID, array $objects);
 
@@ -68,7 +70,7 @@ public function populate($objectTypeID, array $objects);
      * Returns whether the affected content may be removed.
      *
      * @param ModerationQueue $queue
-     * @return  bool
+     * @return bool
      */
     public function canRemoveContent(ModerationQueue $queue);
 
@@ -78,6 +80,7 @@ public function canRemoveContent(ModerationQueue $queue);
      *
      * @param ModerationQueue $queue
      * @param string $message
+     * @return void
      */
     public function removeContent(ModerationQueue $queue, $message = '');
 }
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueActivationManager.class.php b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueActivationManager.class.php
index 59e872c0c74..77e85104c99 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueActivationManager.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueActivationManager.class.php
@@ -26,7 +26,7 @@ class ModerationQueueActivationManager extends AbstractModerationQueueManager
     /**
      * Enables affected content.
      *
-     * @param ModerationQueue $queue
+     * @return void
      */
     public function enableContent(ModerationQueue $queue)
     {
@@ -60,7 +60,8 @@ public function getLink($queueID)
      *
      * @param string $objectType
      * @param int $objectID
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function addModeratedContent($objectType, $objectID, array $additionalData = [])
@@ -88,8 +89,9 @@ public function addModeratedContent($objectType, $objectID, array $additionalDat
      *
      * @param string $objectType
      * @param int[] $objectIDs
-     * @param   int[]   $containerIDs       format: `objectID => containerID`
-     * @param array $additionalData
+     * @param int[] $containerIDs       format: `objectID => containerID`
+     * @param mixed[] $additionalData
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function addModeratedContents($objectType, array $objectIDs, array $containerIDs, array $additionalData = [])
@@ -111,6 +113,7 @@ public function addModeratedContents($objectType, array $objectIDs, array $conta
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function removeModeratedContent($objectType, array $objectIDs)
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueManager.class.php b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueManager.class.php
index 6ee6b4363c6..0ecda5e9765 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueManager.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueManager.class.php
@@ -200,6 +200,7 @@ public function getObjectTypeIDs(array $definitionIDs)
      *
      * @param int $objectTypeID
      * @param ViewableModerationQueue[] $objects
+     * @return void
      * @throws  SystemException
      */
     public function populate($objectTypeID, array $objects)
@@ -312,6 +313,8 @@ public function getUnreadModerationCount($skipCache = false)
 
     /**
      * Forces the update of non-tracked queues for this user.
+     *
+     * @return void
      */
     protected function forceUserAssignment()
     {
@@ -350,6 +353,7 @@ protected function forceUserAssignment()
      * Saves moderation queue assignments.
      *
      * @param array<int, bool> $assignments
+     * @return void
      */
     public function setAssignment(array $assignments, ?User $user = null)
     {
@@ -381,6 +385,8 @@ public function setAssignment(array $assignments, ?User $user = null)
 
     /**
      * Identifies and removes orphaned queues.
+     *
+     * @return void
      */
     public function identifyOrphans()
     {
@@ -429,6 +435,7 @@ public function identifyOrphans()
      * Removes a list of orphaned queue ids.
      *
      * @param int[] $queueIDs
+     * @return void
      */
     public function removeOrphans(array $queueIDs)
     {
@@ -450,6 +457,7 @@ public function removeOrphans(array $queueIDs)
      * Resets moderation count for all users or optionally only for one user.
      *
      * @param int $userID
+     * @return void
      */
     public function resetModerationCount($userID = null)
     {
@@ -502,6 +510,7 @@ public function getDefinitionNamesByObjectType($objectType)
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      * @throws  SystemException
      */
     public function removeQueues($objectType, array $objectIDs)
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueReportManager.class.php b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueReportManager.class.php
index 94180e53541..ec03144d4d0 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueReportManager.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/ModerationQueueReportManager.class.php
@@ -134,7 +134,8 @@ public function getReportedObject($objectType, $objectID)
      * @param string $objectType
      * @param int $objectID
      * @param string $message
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function addReport($objectType, $objectID, $message, array $additionalData = [])
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/activation/IModerationQueueActivationHandler.class.php b/wcfsetup/install/files/lib/system/moderation/queue/activation/IModerationQueueActivationHandler.class.php
index 4dc74afe636..5d2040ed513 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/activation/IModerationQueueActivationHandler.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/activation/IModerationQueueActivationHandler.class.php
@@ -19,6 +19,7 @@ interface IModerationQueueActivationHandler extends IModerationQueueHandler
      * Enables affected content.
      *
      * @param ModerationQueue $queue
+     * @return void
      */
     public function enableContent(ModerationQueue $queue);
 
@@ -26,7 +27,7 @@ public function enableContent(ModerationQueue $queue);
      * Returns rendered template for disabled content.
      *
      * @param ViewableModerationQueue $queue
-     * @return  string
+     * @return string
      */
     public function getDisabledContent(ViewableModerationQueue $queue);
 }
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/command/AssignUser.class.php b/wcfsetup/install/files/lib/system/moderation/queue/command/AssignUser.class.php
index 007d5a5744e..37f343f1645 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/command/AssignUser.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/command/AssignUser.class.php
@@ -37,7 +37,7 @@ public function __construct(
         $this->eventHandler = EventHandler::getInstance();
     }
 
-    public function __invoke()
+    public function __invoke(): void
     {
         $moderationQueueEditor = new ModerationQueueEditor(new ModerationQueue($this->moderationQueueId));
         if ($this->userId !== null) {
diff --git a/wcfsetup/install/files/lib/system/moderation/queue/report/ArticleModerationQueueReportHandler.class.php b/wcfsetup/install/files/lib/system/moderation/queue/report/ArticleModerationQueueReportHandler.class.php
index 37f6f0b4591..60024fd759e 100644
--- a/wcfsetup/install/files/lib/system/moderation/queue/report/ArticleModerationQueueReportHandler.class.php
+++ b/wcfsetup/install/files/lib/system/moderation/queue/report/ArticleModerationQueueReportHandler.class.php
@@ -76,7 +76,7 @@ public function getReportedObject($objectID)
     }
 
     /**
-     * @param $articleID
+     * @param int $articleID
      * @return ViewableArticle|null
      */
     public function getArticle($articleID)
diff --git a/wcfsetup/install/files/lib/system/notice/NoticeHandler.class.php b/wcfsetup/install/files/lib/system/notice/NoticeHandler.class.php
index adcf200c212..f8eb13fc4cb 100644
--- a/wcfsetup/install/files/lib/system/notice/NoticeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/notice/NoticeHandler.class.php
@@ -67,6 +67,8 @@ public function getVisibleNotices()
 
     /**
      * Disables the display of notices for the active page.
+     *
+     * @return void
      */
     public static function disableNotices()
     {
diff --git a/wcfsetup/install/files/lib/system/option/CaptchaSelectOptionType.class.php b/wcfsetup/install/files/lib/system/option/CaptchaSelectOptionType.class.php
index 19e4e0440d9..b2f86ebf0a6 100644
--- a/wcfsetup/install/files/lib/system/option/CaptchaSelectOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/CaptchaSelectOptionType.class.php
@@ -47,7 +47,7 @@ public function getFormElement(Option $option, $value)
      * Prepares JSON-encoded values for disabling or enabling dependent options.
      *
      * @param Option $option
-     * @return  array
+     * @return array{disableOptions: string, enableOptions: string}
      * @see SelectOptionType::parseEnableOptions()
      */
     protected function parseEnableOptions(Option $option)
diff --git a/wcfsetup/install/files/lib/system/option/CustomOptionHandler.class.php b/wcfsetup/install/files/lib/system/option/CustomOptionHandler.class.php
index cd4a8cc998d..afd68bd4c57 100644
--- a/wcfsetup/install/files/lib/system/option/CustomOptionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/option/CustomOptionHandler.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\option;
 
 use wcf\data\custom\option\CustomOption;
+use wcf\data\option\category\OptionCategory;
 use wcf\data\option\Option;
 use wcf\system\exception\NotImplementedException;
 use wcf\system\exception\UserInputException;
@@ -13,6 +14,9 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends OptionHandler<Option, OptionCategory>
+ * @phpstan-import-type ParsedOption from OptionHandler
  */
 abstract class CustomOptionHandler extends OptionHandler
 {
@@ -45,7 +49,7 @@ public function init()
     /**
      * Returns the parsed options.
      *
-     * @return  array
+     * @return list<ParsedOption>
      */
     public function getOptions()
     {
@@ -72,6 +76,8 @@ public function readData()
 
     /**
      * Resets the option values.
+     *
+     * @return void
      */
     public function resetOptionValues()
     {
@@ -81,7 +87,7 @@ public function resetOptionValues()
     /**
      * Returns the option values.
      *
-     * @return  array
+     * @return array<string, string>
      */
     public function getOptionValues()
     {
@@ -91,7 +97,8 @@ public function getOptionValues()
     /**
      * Sets the option values.
      *
-     * @param array $values
+     * @param array<string, string> $values
+     * @return void
      */
     public function setOptionValues(array $values)
     {
@@ -106,8 +113,9 @@ public function getOption($optionName)
         $optionData = parent::getOption($optionName);
 
         if (isset($this->optionValues[$optionName])) {
-            /** @noinspection PhpUndefinedMethodInspection */
-            $optionData['object']->setOptionValue($this->optionValues[$optionName]);
+            $object = $optionData['object'];
+            \assert($object instanceof CustomOption);
+            $object->setOptionValue($this->optionValues[$optionName]);
         }
 
         return $optionData;
diff --git a/wcfsetup/install/files/lib/system/option/FileOptionType.class.php b/wcfsetup/install/files/lib/system/option/FileOptionType.class.php
index 4b8d77224b8..0befb288279 100644
--- a/wcfsetup/install/files/lib/system/option/FileOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/FileOptionType.class.php
@@ -29,6 +29,7 @@ class FileOptionType extends AbstractOptionType
      * Creates the upload handler for the given option.
      *
      * @param Option $option
+     * @return void
      */
     protected function createUploadHandler(Option $option)
     {
diff --git a/wcfsetup/install/files/lib/system/option/FloatOptionType.class.php b/wcfsetup/install/files/lib/system/option/FloatOptionType.class.php
index 050508ab158..768207eab43 100644
--- a/wcfsetup/install/files/lib/system/option/FloatOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/FloatOptionType.class.php
@@ -71,6 +71,8 @@ public function getCondition(PreparedStatementConditionBuilder &$conditions, Opt
 
     /**
      * Converts a localized string value into a float value.
+     *
+     * @param string $value
      */
     protected function toFloat($value): float
     {
diff --git a/wcfsetup/install/files/lib/system/option/IOptionHandler.class.php b/wcfsetup/install/files/lib/system/option/IOptionHandler.class.php
index c2e2c49f772..a28c5d97053 100644
--- a/wcfsetup/install/files/lib/system/option/IOptionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/option/IOptionHandler.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\option;
 
+use wcf\data\option\Option;
+
 /**
  * Every option handler has to implement this interface.
  *
@@ -23,14 +25,15 @@ public function __construct($supportI18n, $languageItemPattern = '', $categoryNa
     /**
      * Reads user input from given source array.
      *
-     * @param array $source
+     * @param mixed[] $source
+     * @return void
      */
     public function readUserInput(array &$source);
 
     /**
      * Validates user input, returns an array with all occurred errors.
      *
-     * @return  array
+     * @return array<string, mixed>
      */
     public function validate();
 
@@ -39,7 +42,7 @@ public function validate();
      *
      * @param string $parentCategoryName
      * @param int $level
-     * @return  array
+     * @return mixed[]
      */
     public function getOptionTree($parentCategoryName = '', $level = 0);
 
@@ -48,12 +51,14 @@ public function getOptionTree($parentCategoryName = '', $level = 0);
      *
      * @param string $categoryName
      * @param bool $inherit
-     * @return  array
+     * @return list<Option>
      */
     public function getCategoryOptions($categoryName = '', $inherit = true);
 
     /**
      * Initializes i18n support.
+     *
+     * @return void
      */
     public function readData();
 
@@ -62,12 +67,14 @@ public function readData();
      *
      * @param string $categoryName
      * @param string $optionPrefix
-     * @return  array
+     * @return array<int, mixed>
      */
     public function save($categoryName = null, $optionPrefix = null);
 
     /**
      * Initializes active options.
+     *
+     * @return void
      */
     public function init();
 }
diff --git a/wcfsetup/install/files/lib/system/option/IOptionType.class.php b/wcfsetup/install/files/lib/system/option/IOptionType.class.php
index ae92ee57dd3..b5480563c15 100644
--- a/wcfsetup/install/files/lib/system/option/IOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/IOptionType.class.php
@@ -29,6 +29,7 @@ public function getFormElement(Option $option, $value);
      *
      * @param Option $option
      * @param string $newValue
+     * @return void
      */
     public function validate(Option $option, $newValue);
 
diff --git a/wcfsetup/install/files/lib/system/option/ISearchableConditionUserOption.class.php b/wcfsetup/install/files/lib/system/option/ISearchableConditionUserOption.class.php
index acab705c40f..12919baa835 100644
--- a/wcfsetup/install/files/lib/system/option/ISearchableConditionUserOption.class.php
+++ b/wcfsetup/install/files/lib/system/option/ISearchableConditionUserOption.class.php
@@ -22,6 +22,7 @@ interface ISearchableConditionUserOption extends ISearchableUserOption
      * @param UserList $userList
      * @param Option $option
      * @param mixed $value
+     * @return void
      */
     public function addCondition(UserList $userList, Option $option, $value);
 
diff --git a/wcfsetup/install/files/lib/system/option/MultiSelectOptionType.class.php b/wcfsetup/install/files/lib/system/option/MultiSelectOptionType.class.php
index 5fd5c043448..0602e15289c 100644
--- a/wcfsetup/install/files/lib/system/option/MultiSelectOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/MultiSelectOptionType.class.php
@@ -125,7 +125,7 @@ public function getCondition(PreparedStatementConditionBuilder &$conditions, Opt
     public function addCondition(UserList $userList, Option $option, $value)
     {
         if (!\is_array($value) || empty($value)) {
-            return false;
+            return;
         }
         $value = ArrayUtil::trim($value, false);
 
diff --git a/wcfsetup/install/files/lib/system/option/OptionHandler.class.php b/wcfsetup/install/files/lib/system/option/OptionHandler.class.php
index 45e161ea2e0..27034442ac8 100644
--- a/wcfsetup/install/files/lib/system/option/OptionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/option/OptionHandler.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\option;
 
+use wcf\data\DatabaseObject;
 use wcf\data\option\category\OptionCategory;
 use wcf\data\option\Option;
 use wcf\system\application\ApplicationHandler;
@@ -20,6 +21,16 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template TOption of Option = Option
+ * @template TOptionCategory of DatabaseObject = OptionCategory
+ * @phpstan-type ParsedOption array{
+ *  object: TOption,
+ *  value: mixed,
+ *  html: string,
+ *  cssClassName: string,
+ *  hideLabelInSearch: bool,
+ * }|null
  */
 class OptionHandler implements IOptionHandler
 {
@@ -43,19 +54,19 @@ class OptionHandler implements IOptionHandler
 
     /**
      * list of all options
-     * @var Option[]
+     * @var TOption[]
      */
     public $cachedOptions;
 
     /**
      * category structure
-     * @var array
+     * @var mixed[]
      */
     public $cachedCategoryStructure;
 
     /**
      * option structure
-     * @var array
+     * @var mixed[]
      */
     public $cachedOptionToCategories;
 
@@ -94,7 +105,7 @@ class OptionHandler implements IOptionHandler
 
     /**
      * options of the active category
-     * @var Option[]
+     * @var TOption[]
      */
     public $options = [];
 
@@ -112,7 +123,7 @@ class OptionHandler implements IOptionHandler
 
     /**
      * option values
-     * @var mixed[]
+     * @var array<string, string>
      */
     public $optionValues = [];
 
@@ -347,7 +358,7 @@ public function save($categoryName = null, $optionPrefix = null)
      * Returns a parsed option.
      *
      * @param string $optionName
-     * @return  ?array
+     * @return ParsedOption
      */
     protected function getOption($optionName)
     {
@@ -370,7 +381,7 @@ protected function getOption($optionName)
      * Wrapper function to preserve backwards compatibility with the visibility of `getOption()`.
      *
      * @param string $optionName
-     * @return array
+     * @return ParsedOption
      * @since 5.2
      */
     public function getSingleOption($optionName)
@@ -381,7 +392,8 @@ public function getSingleOption($optionName)
     /**
      * Validates an option.
      *
-     * @param Option $option
+     * @param TOption $option
+     * @return void
      * @throws  UserInputException
      */
     protected function validateOption(Option $option)
@@ -413,6 +425,9 @@ protected function validateOption(Option $option)
 
     /**
      * @inheritDoc
+     *
+     * @param string $type
+     * @return string
      */
     protected function getFormElement($type, Option $option)
     {
@@ -490,6 +505,8 @@ protected function getClassName($optionType)
 
     /**
      * Fetches all options and option categories from cache.
+     *
+     * @return void
      */
     protected function readCache()
     {
@@ -523,6 +540,7 @@ public function init()
      * Removes any option that is not listed in the provided list.
      *
      * @param string[] $optionNames
+     * @return void
      * @since 5.2
      */
     public function filterOptions(array $optionNames)
@@ -536,6 +554,7 @@ public function filterOptions(array $optionNames)
      * Creates a list of all active options.
      *
      * @param string $parentCategoryName
+     * @return void
      */
     protected function loadActiveOptions($parentCategoryName)
     {
@@ -578,7 +597,7 @@ protected function checkCategory(OptionCategory $category)
     /**
      * Checks the required permissions and options of an option.
      *
-     * @param Option $option
+     * @param TOption $option
      * @return  bool
      */
     protected function checkOption(Option $option)
@@ -589,7 +608,7 @@ protected function checkOption(Option $option)
     /**
      * Checks visibility of an option.
      *
-     * @param Option $option
+     * @param TOption $option
      * @return  bool
      */
     protected function checkVisibility(Option $option)
diff --git a/wcfsetup/install/files/lib/system/option/SelectOptionType.class.php b/wcfsetup/install/files/lib/system/option/SelectOptionType.class.php
index 453c429b215..568fe66c54a 100644
--- a/wcfsetup/install/files/lib/system/option/SelectOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/SelectOptionType.class.php
@@ -14,6 +14,9 @@
  */
 class SelectOptionType extends RadioButtonOptionType
 {
+    /**
+     * @var bool
+     */
     protected $allowEmptyValue = false;
 
     /**
@@ -56,7 +59,7 @@ public function getSearchFormElement(Option $option, $value)
      * Prepares JSON-encoded values for disabling or enabling dependent options.
      *
      * @param Option $option
-     * @return  array
+     * @return array{disableOptions: string, enableOptions: string}
      */
     protected function parseEnableOptions(Option $option)
     {
diff --git a/wcfsetup/install/files/lib/system/option/user/UserOptionHandler.class.php b/wcfsetup/install/files/lib/system/option/user/UserOptionHandler.class.php
index ab9be617ccf..5c9268f9d14 100644
--- a/wcfsetup/install/files/lib/system/option/user/UserOptionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/option/user/UserOptionHandler.class.php
@@ -25,9 +25,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @property    UserOptionCategory $cachedCategories
- * @property    UserOption[] $cachedOptions
- * @property    UserOption[] $options
+ * @extends OptionHandler<UserOption, UserOptionCategory>
  */
 class UserOptionHandler extends OptionHandler
 {
@@ -89,6 +87,7 @@ public function init()
      * Shows empty options.
      *
      * @param bool $show
+     * @return void
      */
     public function showEmptyOptions($show = true)
     {
@@ -99,6 +98,7 @@ public function showEmptyOptions($show = true)
      * Sets registration mode.
      *
      * @param bool $inRegistration
+     * @return void
      */
     public function setInRegistration($inRegistration = true)
     {
@@ -112,6 +112,7 @@ public function setInRegistration($inRegistration = true)
      * Enables edit mode.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableEditMode($enable = true)
     {
@@ -122,6 +123,7 @@ public function enableEditMode($enable = true)
      * Enables search mode.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableSearchMode($enable = true)
     {
@@ -135,6 +137,7 @@ public function enableSearchMode($enable = true)
      * Sets option values for a certain user.
      *
      * @param User $user
+     * @return void
      */
     public function setUser(User $user)
     {
@@ -150,6 +153,8 @@ public function setUser(User $user)
 
     /**
      * Resets the option values.
+     *
+     * @return void
      */
     public function resetOptionValues()
     {
@@ -168,6 +173,7 @@ public function resetOptionValues()
      * during automatic cronjob execution (always done as a guest), the conditions are properly set.
      *
      * @param bool $enable
+     * @return void
      */
     public function enableConditionMode($enable = true)
     {
@@ -181,7 +187,7 @@ public function enableConditionMode($enable = true)
     /**
      * Returns the option values.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getOptionValues()
     {
@@ -191,7 +197,8 @@ public function getOptionValues()
     /**
      * Sets the option values.
      *
-     * @param array $values
+     * @param mixed[] $values
+     * @return void
      */
     public function setOptionValues(array $values)
     {
@@ -206,7 +213,9 @@ public function getOption($optionName)
         $optionData = parent::getOption($optionName);
 
         if (!$this->editMode && !$this->searchMode) {
-            $optionData['object'] = new ViewableUserOption($optionData['object']);
+            /** @var UserOption $option */
+            $option = $optionData['object'];
+            $optionData['object'] = new ViewableUserOption($option);
             if ($this->user !== null) {
                 $optionData['object']->setOptionValue($this->user);
             }
@@ -380,6 +389,8 @@ public function readData()
 
     /**
      * @inheritDoc
+     * @param mixed[] $source
+     * @return void
      */
     public function readUserInput(array &$source)
     {
diff --git a/wcfsetup/install/files/lib/system/option/user/group/BBCodeSelectUserGroupOptionType.class.php b/wcfsetup/install/files/lib/system/option/user/group/BBCodeSelectUserGroupOptionType.class.php
index 34cf4743439..90d2be520b3 100644
--- a/wcfsetup/install/files/lib/system/option/user/group/BBCodeSelectUserGroupOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/user/group/BBCodeSelectUserGroupOptionType.class.php
@@ -80,6 +80,8 @@ public function getFormElement(Option $option, $value)
 
     /**
      * Loads the list of BBCodes for the HTML select element.
+     *
+     * @return void
      */
     protected function loadBBCodeSelection()
     {
diff --git a/wcfsetup/install/files/lib/system/option/user/group/IUserGroupGroupOptionType.class.php b/wcfsetup/install/files/lib/system/option/user/group/IUserGroupGroupOptionType.class.php
index 53aadbeb443..19d1c0e1f22 100644
--- a/wcfsetup/install/files/lib/system/option/user/group/IUserGroupGroupOptionType.class.php
+++ b/wcfsetup/install/files/lib/system/option/user/group/IUserGroupGroupOptionType.class.php
@@ -18,6 +18,7 @@ interface IUserGroupGroupOptionType
      * Sets the active user group object.
      *
      * @param UserGroup $group
+     * @return void
      */
     public function setUserGroup(UserGroup $group);
 
diff --git a/wcfsetup/install/files/lib/system/option/user/group/UserGroupOptionHandler.class.php b/wcfsetup/install/files/lib/system/option/user/group/UserGroupOptionHandler.class.php
index 16aa9663a89..a425f92280a 100644
--- a/wcfsetup/install/files/lib/system/option/user/group/UserGroupOptionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/option/user/group/UserGroupOptionHandler.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\option\user\group;
 
 use wcf\data\option\Option;
+use wcf\data\user\group\option\category\UserGroupOptionCategory;
 use wcf\data\user\group\option\UserGroupOption;
 use wcf\data\user\group\UserGroup;
 use wcf\system\cache\builder\UserGroupOptionCacheBuilder;
@@ -17,6 +18,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends OptionHandler<UserGroupOption, UserGroupOptionCategory>
  */
 class UserGroupOptionHandler extends OptionHandler
 {
@@ -48,6 +51,7 @@ class UserGroupOptionHandler extends OptionHandler
      * Sets current user group.
      *
      * @param UserGroup $group
+     * @return void
      */
     public function setUserGroup(UserGroup $group)
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageArchive.class.php b/wcfsetup/install/files/lib/system/package/PackageArchive.class.php
index 034ef28062f..71e75765cfb 100644
--- a/wcfsetup/install/files/lib/system/package/PackageArchive.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageArchive.class.php
@@ -5,7 +5,6 @@
 use wcf\data\package\Package;
 use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\exception\SystemException;
-use wcf\system\io\File;
 use wcf\system\io\Tar;
 use wcf\system\package\validation\PackageValidationException;
 use wcf\system\WCF;
@@ -20,6 +19,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type Instruction array{pip: string, value: string, attributes: array<string, string>}
+ * @phpstan-type VoidInstruction array{pip: self::VOID_MARKER, value: ''}
  */
 class PackageArchive
 {
@@ -37,37 +38,52 @@ class PackageArchive
 
     /**
      * general package information
-     * @var array
+     * @var array{}|array{
+     *  applicationDirectory?: string,
+     *  date: string|false,
+     *  isApplication: int,
+     *  name: string,
+     *  packageDescription?: array<string, string>,
+     *  packageName: array<string, string>,
+     *  packageURL: string,
+     *  version: string,
+     * }
      */
     protected $packageInfo = [];
 
     /**
      * author information
-     * @var array
+     * @var array{}|array{
+     *  author: string,
+     *  authorURL?: string,
+     * }
      */
     protected $authorInfo = [];
 
     /**
      * list of requirements
-     * @var array
+     * @var array<string, array{file?: string, name: string, minversion: string}>
      */
     protected $requirements = [];
 
     /**
      * list of optional packages
-     * @var array
+     * @var list<array{file?: string, name: string}&array<string, string>>
      */
     protected $optionals = [];
 
     /**
      * list of excluded packages
-     * @var array
+     * @var list<array{name: string, version: string}>
      */
     protected $excludedPackages = [];
 
     /**
      * list of instructions
-     * @var mixed[][]
+     * @var array{
+     *  install: Instruction[],
+     *  update: array<string, Instruction[]|VoidInstruction>
+     * }
      */
     protected $instructions = [
         'install' => [],
@@ -119,6 +135,8 @@ public function getTar()
 
     /**
      * Opens the package archive and reads package information.
+     *
+     * @return void
      */
     public function openArchive()
     {
@@ -137,6 +155,8 @@ public function openArchive()
 
     /**
      * Extracts information about this package (parses package.xml).
+     *
+     * @return void
      */
     protected function readPackageInfo()
     {
@@ -209,7 +229,7 @@ protected function readPackageInfo()
                             $languageCode = $element->getAttribute('language');
                         }
 
-                        $this->packageInfo[$name][$languageCode] = StringUtil::trim($element->nodeValue);
+                        $this->packageInfo[$name][$languageCode] = StringUtil::trim($element->textContent);
                         break;
 
                     case 'isapplication':
@@ -222,11 +242,11 @@ protected function readPackageInfo()
                             );
                         }
 
-                        $this->packageInfo['isApplication'] = \intval($element->nodeValue);
+                        $this->packageInfo['isApplication'] = \intval($element->textContent);
                         break;
 
                     case 'applicationdirectory':
-                        if (isset($this->packageInfo['applicationdirectory'])) {
+                        if (isset($this->packageInfo['applicationDirectory'])) {
                             throw new PackageValidationException(
                                 PackageValidationException::DUPLICATE_PACKAGE_INFORMATION,
                                 [
@@ -235,8 +255,8 @@ protected function readPackageInfo()
                             );
                         }
 
-                        if (\preg_match('~^[a-z0-9\-\_]+$~', $element->nodeValue)) {
-                            $this->packageInfo['applicationDirectory'] = $element->nodeValue;
+                        if (\preg_match('~^[a-z0-9\-\_]+$~', $element->textContent)) {
+                            $this->packageInfo['applicationDirectory'] = $element->textContent;
                         }
                         break;
 
@@ -250,7 +270,7 @@ protected function readPackageInfo()
                             );
                         }
 
-                        $this->packageInfo['packageURL'] = $element->nodeValue;
+                        $this->packageInfo['packageURL'] = $element->textContent;
                         break;
 
                     case 'version':
@@ -263,14 +283,14 @@ protected function readPackageInfo()
                             );
                         }
 
-                        if (!Package::isValidVersion($element->nodeValue)) {
+                        if (!Package::isValidVersion($element->textContent)) {
                             throw new PackageValidationException(
                                 PackageValidationException::INVALID_PACKAGE_VERSION,
-                                ['packageVersion' => $element->nodeValue]
+                                ['packageVersion' => $element->textContent]
                             );
                         }
 
-                        $this->packageInfo['version'] = $element->nodeValue;
+                        $this->packageInfo['version'] = $element->textContent;
                         break;
 
                     case 'date':
@@ -283,9 +303,9 @@ protected function readPackageInfo()
                             );
                         }
 
-                        DateUtil::validateDate($element->nodeValue);
+                        DateUtil::validateDate($element->textContent);
 
-                        $this->packageInfo['date'] = @\strtotime($element->nodeValue);
+                        $this->packageInfo['date'] = @\strtotime($element->textContent);
                         break;
 
                     default:
@@ -330,7 +350,7 @@ protected function readPackageInfo()
                             $name = 'authorURL';
                         }
 
-                        $this->authorInfo[$name] = StringUtil::trim($element->nodeValue);
+                        $this->authorInfo[$name] = StringUtil::trim($element->textContent);
                         break;
                     default:
                         throw new PackageValidationException(
@@ -366,15 +386,15 @@ protected function readPackageInfo()
         // get required packages
         $elements = $xpath->query('child::ns:requiredpackages/ns:requiredpackage', $package);
         foreach ($elements as $element) {
-            if (!Package::isValidPackageName($element->nodeValue)) {
+            if (!Package::isValidPackageName($element->textContent)) {
                 throw new PackageValidationException(
                     PackageValidationException::INVALID_PACKAGE_NAME,
-                    ['packageName' => $element->nodeValue]
+                    ['packageName' => $element->textContent]
                 );
             }
 
             // read attributes
-            $data = ['name' => $element->nodeValue];
+            $data = ['name' => $element->textContent];
             $attributes = $xpath->query('attribute::*', $element);
             foreach ($attributes as $attribute) {
                 \assert($attribute instanceof \DOMAttr);
@@ -389,12 +409,12 @@ protected function readPackageInfo()
                     PackageValidationException::INVALID_REQUIRED_PACKAGE_VERSION_NUMBER,
                     [
                         'version' => $data['minversion'] ?? '',
-                        'packageName' => $element->nodeValue,
+                        'packageName' => $element->textContent,
                     ]
                 );
             }
 
-            $this->requirements[$element->nodeValue] = $data;
+            $this->requirements[$element->textContent] = $data;
         }
 
         if (!isset($this->requirements['com.woltlab.wcf'])) {
@@ -410,10 +430,7 @@ protected function readPackageInfo()
             //
             // This stops old packages that are missing both exclude and compatibility tags from being installable,
             // it also nicely excludes all versions were compatibility tags were non-deprecated (i.e. 5.2).
-            if (
-                !isset($this->requirements['com.woltlab.wcf']['minversion'])
-                || Package::compareVersion($this->requirements['com.woltlab.wcf']['minversion'], '5.4.22', '<')
-            ) {
+            if (Package::compareVersion($this->requirements['com.woltlab.wcf']['minversion'], '5.4.22', '<')) {
                 throw new PackageValidationException(PackageValidationException::ANCIENT_COM_WOLTLAB_WCF_REQUIREMENT);
             }
         }
@@ -421,15 +438,15 @@ protected function readPackageInfo()
         // get optional packages
         $elements = $xpath->query('child::ns:optionalpackages/ns:optionalpackage', $package);
         foreach ($elements as $element) {
-            if (!Package::isValidPackageName($element->nodeValue)) {
+            if (!Package::isValidPackageName($element->textContent)) {
                 throw new PackageValidationException(
                     PackageValidationException::INVALID_PACKAGE_NAME,
-                    ['packageName' => $element->nodeValue]
+                    ['packageName' => $element->textContent]
                 );
             }
 
             // read attributes
-            $data = ['name' => $element->nodeValue];
+            $data = ['name' => $element->textContent];
             $attributes = $xpath->query('attribute::*', $element);
             foreach ($attributes as $attribute) {
                 \assert($attribute instanceof \DOMAttr);
@@ -442,22 +459,22 @@ protected function readPackageInfo()
         // get excluded packages
         $elements = $xpath->query('child::ns:excludedpackages/ns:excludedpackage', $package);
         foreach ($elements as $element) {
-            if (!Package::isValidPackageName($element->nodeValue)) {
+            if (!Package::isValidPackageName($element->textContent)) {
                 throw new PackageValidationException(
                     PackageValidationException::INVALID_PACKAGE_NAME,
-                    ['packageName' => $element->nodeValue]
+                    ['packageName' => $element->textContent]
                 );
             }
 
-            if ($element->nodeValue === $this->packageInfo['name']) {
+            if ($element->textContent === $this->packageInfo['name']) {
                 throw new PackageValidationException(
                     PackageValidationException::SELF_EXCLUDE,
-                    ['packageName' => $element->nodeValue]
+                    ['packageName' => $element->textContent]
                 );
             }
 
             // read attributes
-            $data = ['name' => $element->nodeValue];
+            $data = ['name' => $element->textContent];
             $attributes = $xpath->query('attribute::*', $element);
             foreach ($attributes as $attribute) {
                 \assert($attribute instanceof \DOMAttr);
@@ -472,7 +489,7 @@ protected function readPackageInfo()
                     PackageValidationException::INVALID_EXCLUDED_PACKAGE_VERSION_NUMBER,
                     [
                         'version' => $data['version'] ?? '',
-                        'packageName' => $element->nodeValue,
+                        'packageName' => $element->textContent,
                     ]
                 );
             }
@@ -505,7 +522,7 @@ protected function readPackageInfo()
                 $instructionData[] = [
                     'attributes' => $data,
                     'pip' => $instruction->getAttribute('type'),
-                    'value' => $instruction->nodeValue,
+                    'value' => $instruction->textContent,
                 ];
             }
 
@@ -539,6 +556,8 @@ protected function readPackageInfo()
 
     /**
      * Closes and deletes the tar archive of this package.
+     *
+     * @return void
      */
     public function deleteArchive()
     {
@@ -626,7 +645,7 @@ public function getLocalizedPackageInfo(string $name): string
     /**
      * Returns a list of all requirements of this package.
      *
-     * @return  array
+     * @return array<string, array{file?: string, name: string, minversion: string}>
      */
     public function getRequirements()
     {
@@ -636,7 +655,7 @@ public function getRequirements()
     /**
      * Returns a list of all delivered optional packages of this package.
      *
-     * @return  array
+     * @return list<array{file?: string, name: string}&array<string, string>>
      */
     public function getOptionals()
     {
@@ -646,7 +665,7 @@ public function getOptionals()
     /**
      * Returns a list of excluded packages.
      *
-     * @return  array
+     * @return list<array{name: string, version: string}>
      */
     public function getExcludedPackages()
     {
@@ -656,7 +675,7 @@ public function getExcludedPackages()
     /**
      * Returns the package installation instructions.
      *
-     * @return  array
+     * @return Instruction[]
      */
     public function getInstallInstructions()
     {
@@ -666,7 +685,7 @@ public function getInstallInstructions()
     /**
      * Returns the package update instructions.
      *
-     * @return  array
+     * @return array<string, Instruction[]|VoidInstruction>
      * @since 6.0
      */
     public function getAllUpdateInstructions()
@@ -678,6 +697,7 @@ public function getAllUpdateInstructions()
      * Returns the appropriate update instructions to update the given package version,
      * `null` if no appropriate instruction could be found.
      *
+     * @return Instruction[]|VoidInstruction|null
      * @since 6.0
      */
     public function getUpdateInstructionsFor(string $version): ?array
@@ -695,7 +715,7 @@ public function getUpdateInstructionsFor(string $version): ?array
      * Checks which package requirements do already exist in database.
      * Returns a list with the existing requirements.
      *
-     * @return  array
+     * @return array<string, array<string, string|int>>
      */
     public function getExistingRequirements()
     {
@@ -726,7 +746,7 @@ public function getExistingRequirements()
     /**
      * Returns a list of all open requirements of this package.
      *
-     * @return  array
+     * @return array<string, array<string, string|int>>
      */
     public function getOpenRequirements()
     {
@@ -739,21 +759,17 @@ public function getOpenRequirements()
             if (isset($existingPackages[$requirement['name']])) {
                 // package does already exist
                 // maybe an update is necessary
-                if (isset($requirement['minversion'])) {
-                    if (
-                        Package::compareVersion(
-                            $existingPackages[$requirement['name']]['packageVersion'],
-                            $requirement['minversion']
-                        ) >= 0
-                    ) {
-                        // package does already exist in needed version
-                        // skip installation of requirement
-                        continue;
-                    } else {
-                        $requirement['existingVersion'] = $existingPackages[$requirement['name']]['packageVersion'];
-                    }
-                } else {
+                if (
+                    Package::compareVersion(
+                        $existingPackages[$requirement['name']]['packageVersion'],
+                        $requirement['minversion']
+                    ) >= 0
+                ) {
+                    // package does already exist in needed version
+                    // skip installation of requirement
                     continue;
+                } else {
+                    $requirement['existingVersion'] = $existingPackages[$requirement['name']]['packageVersion'];
                 }
 
                 $requirement['packageID'] = $existingPackages[$requirement['name']]['packageID'];
@@ -777,8 +793,8 @@ public function getOpenRequirements()
      *
      * @param string $filename
      * @param string $tempPrefix
-     * @return  string
-     * @throws  PackageValidationException
+     * @return string
+     * @throws PackageValidationException
      */
     public function extractTar($filename, $tempPrefix = 'package_')
     {
@@ -805,7 +821,7 @@ public function extractTar($filename, $tempPrefix = 'package_')
     /**
      * Returns a list of packages which exclude this package.
      *
-     * @return  Package[]
+     * @return Package[]
      */
     public function getConflictedExcludingPackages()
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
index 72041e8f53b..1d713d3bdd4 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
@@ -94,11 +94,6 @@ class PackageInstallationDispatcher
      */
     protected $previousPackageData;
 
-    /**
-     * Creates a new instance of PackageInstallationDispatcher.
-     *
-     * @param PackageInstallationQueue $queue
-     */
     public function __construct(PackageInstallationQueue $queue)
     {
         $this->queue = $queue;
@@ -111,6 +106,7 @@ public function __construct(PackageInstallationQueue $queue)
      * Sets data of previous package in queue.
      *
      * @param string[] $packageData
+     * @return void
      */
     public function setPreviousPackage(array $packageData)
     {
@@ -384,8 +380,9 @@ protected function setupDeveloperMode(): void
     /**
      * Logs an installation step.
      *
-     * @param array $node data of the executed node
+     * @param mixed[] $node data of the executed node
      * @param $log optional additional log text
+     * @return void
      */
     protected function logInstallationStep(array $node = [], string $log = ''): void
     {
@@ -416,6 +413,10 @@ protected function logInstallationStep(array $node = [], string $log = ''): void
         );
     }
 
+    /**
+     * @param mixed[] $nodeData
+     * @return PackageInstallationStep
+     */
     protected function handleStartMarker(array $nodeData)
     {
         (new AuditLogger())->log(
@@ -450,6 +451,9 @@ protected function handleStartMarker(array $nodeData)
         return new PackageInstallationStep();
     }
 
+    /**
+     * @return PackageInstallationStep
+     */
     protected function handleEndMarker()
     {
         (new AuditLogger())->log(
@@ -502,6 +506,7 @@ public function getArchive()
      * Installs current package.
      *
      * @param mixed[] $nodeData
+     * @return PackageInstallationStep
      * @throws  SystemException
      */
     protected function installPackage(array $nodeData): PackageInstallationStep
@@ -646,7 +651,7 @@ protected function installPackage(array $nodeData): PackageInstallationStep
     /**
      * Creates a new package based on the given data and returns it.
      *
-     * @param array $packageData
+     * @param mixed[] $packageData
      * @return  Package
      * @since   5.2
      */
@@ -664,6 +669,8 @@ protected function createPackage(array $packageData)
 
     /**
      * Saves the localized package info.
+     *
+     * @return void
      */
     protected function saveLocalizedPackageInfos()
     {
@@ -713,6 +720,7 @@ protected function saveLocalizedPackageInfos()
      * @param LanguageCategory $languageCategory
      * @param Package $package
      * @param string $infoName
+     * @return void
      */
     protected function saveLocalizedPackageInfo(
         PreparedStatement $statement,
@@ -822,7 +830,8 @@ protected function executePIP(array $nodeData): PackageInstallationStep
      * Displays a list to select optional packages or installs selection.
      *
      * @param string $currentNode
-     * @param array $nodeData
+     * @param mixed[] $nodeData
+     * @return PackageInstallationStep
      */
     protected function selectOptionalPackages(string $currentNode, array $nodeData): PackageInstallationStep
     {
@@ -1131,6 +1140,8 @@ public function getAction()
 
     /**
      * Updates queue information.
+     *
+     * @return void
      */
     public function updatePackage()
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationFormManager.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationFormManager.class.php
index 22645fc7a49..ee3028f6f06 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationFormManager.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationFormManager.class.php
@@ -20,6 +20,7 @@ abstract class PackageInstallationFormManager
      * Handles a POST or GET request.
      *
      * @param PackageInstallationQueue $queue
+     * @return void
      */
     public static function handleRequest(PackageInstallationQueue $queue)
     {
@@ -42,6 +43,7 @@ public static function handleRequest(PackageInstallationQueue $queue)
      *
      * @param PackageInstallationQueue $queue
      * @param FormDocument $document
+     * @return void
      */
     public static function registerForm(PackageInstallationQueue $queue, FormDocument $document)
     {
@@ -80,7 +82,7 @@ public static function findForm(PackageInstallationQueue $queue, $formName)
      * @param PackageInstallationQueue $queue
      * @param FormDocument $document
      */
-    private static function insertForm(PackageInstallationQueue $queue, FormDocument $document)
+    private static function insertForm(PackageInstallationQueue $queue, FormDocument $document): void
     {
         $sql = "INSERT INTO wcf1_package_installation_form
                             (queueID, formName, document)
@@ -99,7 +101,7 @@ private static function insertForm(PackageInstallationQueue $queue, FormDocument
      * @param PackageInstallationQueue $queue
      * @param FormDocument $document
      */
-    private static function updateForm(PackageInstallationQueue $queue, FormDocument $document)
+    private static function updateForm(PackageInstallationQueue $queue, FormDocument $document): void
     {
         $sql = "UPDATE  wcf1_package_installation_form
                 SET     document = ?
@@ -117,6 +119,7 @@ private static function updateForm(PackageInstallationQueue $queue, FormDocument
      * Deletes form documents associated with given queue.
      *
      * @param PackageInstallationQueue $queue
+     * @return void
      */
     public static function deleteForms(PackageInstallationQueue $queue)
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationNodeBuilder.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationNodeBuilder.class.php
index e8407193d48..1a4565ebb8d 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationNodeBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationNodeBuilder.class.php
@@ -16,6 +16,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-import-type Instruction from PackageArchive
+ * @phpstan-import-type VoidInstruction from PackageArchive
  */
 class PackageInstallationNodeBuilder
 {
@@ -61,11 +63,6 @@ class PackageInstallationNodeBuilder
      */
     private static $pendingPackages = [];
 
-    /**
-     * Creates a new instance of PackageInstallationNodeBuilder
-     *
-     * @param PackageInstallationDispatcher $installation
-     */
     public function __construct(PackageInstallationDispatcher $installation)
     {
         $this->installation = $installation;
@@ -73,6 +70,8 @@ public function __construct(PackageInstallationDispatcher $installation)
 
     /**
      * Sets parent node.
+     *
+     * @return void
      */
     public function setParentNode(string $parentNode)
     {
@@ -81,6 +80,8 @@ public function setParentNode(string $parentNode)
 
     /**
      * Builds nodes for current installation queue.
+     *
+     * @return void
      */
     public function buildNodes()
     {
@@ -250,7 +251,7 @@ public function getInstallationTypeByQueue(int $queueID): string
     /**
      * Returns data for current node.
      *
-     * @return  array
+     * @return list<array{nodeType: string, nodeData: string, sequenceNo: int}>
      */
     public function getNodeData(string $node)
     {
@@ -270,6 +271,8 @@ public function getNodeData(string $node)
 
     /**
      * Marks a node as completed.
+     *
+     * @return void
      */
     public function completeNode(string $node)
     {
@@ -288,6 +291,8 @@ public function completeNode(string $node)
      * Removes all nodes associated with queue's process no.
      *
      * CAUTION: This method SHOULD NOT be called within the installation process!
+     *
+     * @return void
      */
     public function purgeNodes()
     {
@@ -350,6 +355,7 @@ public function calculateProgress($node)
      *
      * @param string $node
      * @param int $sequenceNo
+     * @return void
      */
     public function cloneNode($node, $sequenceNo)
     {
@@ -406,6 +412,8 @@ public function cloneNode($node, $sequenceNo)
 
     /**
      * Shifts nodes to allow dynamic inserts at runtime.
+     *
+     * @return void
      */
     public function shiftNodes(string $oldParentNode, string $newParentNode)
     {
@@ -421,6 +429,9 @@ public function shiftNodes(string $oldParentNode, string $newParentNode)
         ]);
     }
 
+    /**
+     * @return void
+     */
     protected function buildStartMarkerNode(?string $currentPackageVersion)
     {
         if (!empty($this->node)) {
@@ -446,6 +457,9 @@ protected function buildStartMarkerNode(?string $currentPackageVersion)
         ]);
     }
 
+    /**
+     * @return void
+     */
     protected function buildEndMarkerNode()
     {
         if (!empty($this->node)) {
@@ -471,6 +485,8 @@ protected function buildEndMarkerNode()
 
     /**
      * Builds package node used to install the package itself.
+     *
+     * @return void
      */
     protected function buildPackageNode()
     {
@@ -645,6 +661,8 @@ public function getCurrentNode(): string
     /**
      * Builds package installation plugin nodes, whereas pips could be grouped within
      * one node, differ from each by nothing but the sequence number.
+     *
+     * @param Instruction[]|array{0: VoidInstruction} $instructions
      */
     protected function buildPluginNodes(array $instructions): void
     {
@@ -670,7 +688,7 @@ protected function buildPluginNodes(array $instructions): void
         foreach ($instructions as $pip) {
             $i++;
 
-            if (isset($pip['attributes']['run']) && ($pip['attributes']['run'] == 'standalone')) {
+            if (isset($pip['attributes']['run']) && ($pip['attributes']['run'] === 'standalone')) {
                 // move into a new node unless current one is empty
                 if (!$this->emptyNode) {
                     $this->parentNode = $this->node;
@@ -731,6 +749,8 @@ protected function buildPluginNodes(array $instructions): void
      * Builds nodes for optional packages, whereas each package exists within
      * one node with the same parent node, separated by sequence no (which does
      * not really matter at this point).
+     *
+     * @return void
      */
     protected function buildOptionalNodes()
     {
@@ -817,6 +837,8 @@ protected function buildOptionalNodes()
 
     /**
      * Recursively build nodes for child queues.
+     *
+     * @return void
      */
     protected function buildChildQueues()
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationSQLParser.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationSQLParser.class.php
index f9f3b3510a8..0d715d1949b 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationSQLParser.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationSQLParser.class.php
@@ -36,37 +36,37 @@ class PackageInstallationSQLParser extends SQLParser
 
     /**
      * list of existing database tables
-     * @var array
+     * @var string[]
      */
     protected $existingTables = [];
 
     /**
      * list of logged tables
-     * @var array
+     * @var array<string, int>
      */
     protected $knownTables = [];
 
     /**
      * list of conflicted database tables
-     * @var array
+     * @var array{'CREATE TABLE'?: list<string>}
      */
     protected $conflicts = [];
 
     /**
      * list of created/deleted tables
-     * @var array
+     * @var list<array{tableName: string, packageID: int, action: 'delete'|'insert'}>
      */
     protected $tableLog = [];
 
     /**
      * list of created/deleted columns
-     * @var array
+     * @var list<array{tableName: string, columnName: string, packageID: int, action: 'delete'|'insert'}>
      */
     protected $columnLog = [];
 
     /**
      * list of created/deleted indices
-     * @var array
+     * @var list<array{tableName: string, indexName: string, packageID: int, action: 'delete'|'insert'}>
      */
     protected $indexLog = [];
 
@@ -74,7 +74,6 @@ class PackageInstallationSQLParser extends SQLParser
      * Creates a new PackageInstallationSQLParser object.
      *
      * @param string $queries
-     * @param Package $package
      * @param string $action
      */
     public function __construct($queries, Package $package, $action = 'install')
@@ -88,7 +87,7 @@ public function __construct($queries, Package $package, $action = 'install')
     /**
      * Performs a test of the given queries.
      *
-     * @return  array       conflicts
+     * @return array{'CREATE TABLE'?: list<string>} conflicts
      */
     public function test()
     {
@@ -115,6 +114,8 @@ public function test()
 
     /**
      * Logs executed sql queries
+     *
+     * @return void
      */
     public function log()
     {
@@ -196,6 +197,8 @@ public function log()
 
     /**
      * Fetches known sql tables and their owners from installation log.
+     *
+     * @return void
      */
     protected function getKnownTables()
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationScheduler.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationScheduler.class.php
index 2b0b1614b03..0283f6a04b3 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationScheduler.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationScheduler.class.php
@@ -24,36 +24,48 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type StackEntry array{
+ *  packageName: string,
+ *  packageVersion: string,
+ *  package: string,
+ *  packageID: 0,
+ *  archive: string,
+ *  action: 'install',
+ * }|array{
+ *  packageName: string,
+ *  fromversion: string,
+ *  toVersion: string,
+ *  package: string,
+ *  packageID: int,
+ *  archive: string,
+ *  action: 'update',
+ * }
  */
 final class PackageInstallationScheduler
 {
     /**
      * stack of package installations / updates
-     * @var array
+     * @var array<int, StackEntry>
      */
-    protected $packageInstallationStack = [];
+    private array $packageInstallationStack = [];
 
     /**
-     * list of package update servers
-     * @var PackageUpdateServer[]
+     * @var array<int, PackageUpdateServer>
      */
-    protected $packageUpdateServers = [];
+    private array $packageUpdateServers = [];
 
     /**
      * list of packages to update or install
-     * @var array
+     * @var string[]
      */
-    protected $selectedPackages = [];
+    private array $selectedPackages = [];
 
     /**
-     * virtual package versions
-     * @var array
+     * @var array<string|int, string>
      */
-    protected $virtualPackageVersions = [];
+    private array $virtualPackageVersions = [];
 
     /**
-     * Creates a new instance of PackageInstallationScheduler
-     *
      * @param string[] $selectedPackages
      */
     public function __construct(array $selectedPackages)
@@ -64,10 +76,8 @@ public function __construct(array $selectedPackages)
 
     /**
      * Builds the stack of package installations / updates.
-     *
-     * @param bool $validateInstallInstructions
      */
-    public function buildPackageInstallationStack($validateInstallInstructions = false)
+    public function buildPackageInstallationStack(bool $validateInstallInstructions = false): void
     {
         foreach ($this->selectedPackages as $package => $version) {
             $this->tryToInstallPackage($package, $version, true, $validateInstallInstructions);
@@ -77,17 +87,16 @@ public function buildPackageInstallationStack($validateInstallInstructions = fal
     /**
      * Tries to install a new package. Checks the virtual package version list.
      *
-     * @param string $package package identifier
-     * @param string $minversion preferred package version
-     * @param bool $installOldVersion true, if you want to install the package in the given minversion and not in the newest version
-     * @param bool $validateInstallInstructions
+     * @param $package package identifier
+     * @param $minversion preferred package version
+     * @param $installOldVersion true, if you want to install the package in the given minversion and not in the newest version
      */
-    protected function tryToInstallPackage(
-        $package,
-        $minversion = '',
-        $installOldVersion = false,
-        $validateInstallInstructions = false
-    ) {
+    private function tryToInstallPackage(
+        string $package,
+        string $minversion = '',
+        bool $installOldVersion = false,
+        bool $validateInstallInstructions = false
+    ): void {
         // check virtual package version
         if (isset($this->virtualPackageVersions[$package])) {
             if (
@@ -134,20 +143,12 @@ protected function tryToInstallPackage(
         }
     }
 
-    /**
-     * Installs a new package.
-     *
-     * @param string $package package identifier
-     * @param string $version package version
-     * @param int $stackPosition
-     * @param bool $validateInstallInstructions
-     */
-    protected function installPackage(
-        $package,
-        $version = '',
-        $stackPosition = -1,
-        $validateInstallInstructions = false
-    ) {
+    private function installPackage(
+        string $package,
+        string $version = '',
+        int $stackPosition = -1,
+        bool $validateInstallInstructions = false
+    ): void {
         // get package update versions
         $packageUpdateVersions = PackageUpdateDispatcher::getInstance()->getPackageUpdateVersions($package, $version);
 
@@ -179,10 +180,8 @@ protected function installPackage(
     /**
      * Resolves the package requirements of an package update.
      * Starts the installation or update to higher version of required packages.
-     *
-     * @param int $packageUpdateVersionID
      */
-    protected function resolveRequirements($packageUpdateVersionID)
+    private function resolveRequirements(int $packageUpdateVersionID): void
     {
         // resolve requirements
         $requiredPackages = [];
@@ -249,14 +248,12 @@ protected function resolveRequirements($packageUpdateVersionID)
     /**
      * Tries to download a package from available update servers.
      *
-     * @param string $package package identifier
-     * @param array $packageUpdateVersions package update versions
-     * @param bool $validateInstallInstructions
+     * @param mixed[] $packageUpdateVersions
      * @return  string      tmp filename of a downloaded package
      * @throws  PackageUpdateUnauthorizedException
      * @throws  SystemException
      */
-    protected function downloadPackage($package, $packageUpdateVersions, $validateInstallInstructions = false)
+    private function downloadPackage(string $package, array $packageUpdateVersions, bool $validateInstallInstructions = false): string
     {
         // get download from cache
         if ($filename = $this->getCachedDownload($package, $packageUpdateVersions[0]['packageVersion'])) {
@@ -369,9 +366,18 @@ protected function downloadPackage($package, $packageUpdateVersions, $validateIn
     /**
      * Returns a list of excluded packages.
      *
-     * @return  array
+     * @return list<array{
+     *  package: string,
+     *  packageName: string,
+     *  packageVersion: string,
+     *  action: string,
+     *  conflict: string,
+     *  existingPackage: string,
+     *  existingPackageName: string,
+     *  existingPackageVersion: string,
+     * }>
      */
-    public function getExcludedPackages()
+    public function getExcludedPackages(): array
     {
         $excludedPackages = [];
 
@@ -379,7 +385,7 @@ public function getExcludedPackages()
             $packageInstallations = [];
             $packageIdentifier = [];
             foreach ($this->packageInstallationStack as $packageInstallation) {
-                $packageInstallation['newVersion'] = ($packageInstallation['action'] == 'update' ? $packageInstallation['toVersion'] : $packageInstallation['packageVersion']);
+                $packageInstallation['newVersion'] = ($packageInstallation['action'] === 'update' ? $packageInstallation['toVersion'] : $packageInstallation['packageVersion']);
                 $packageInstallations[] = $packageInstallation;
                 $packageIdentifier[] = $packageInstallation['package'];
             }
@@ -534,20 +540,14 @@ public function getExcludedPackages()
     /**
      * Returns the stack of package installations.
      *
-     * @return  array
+     * @return array<int, StackEntry>
      */
-    public function getPackageInstallationStack()
+    public function getPackageInstallationStack(): array
     {
         return $this->packageInstallationStack;
     }
 
-    /**
-     * Updates an existing package.
-     *
-     * @param int $packageID
-     * @param string $version
-     */
-    protected function updatePackage($packageID, $version)
+    private function updatePackage(int $packageID, string $version): void
     {
         // get package info
         $package = PackageCache::getInstance()->getPackage($packageID);
@@ -664,13 +664,13 @@ protected function updatePackage($packageID, $version)
      * Determines intermediate update steps using a backtracking algorithm in case there is no direct upgrade possible.
      *
      * @param string $package package identifier
-     * @param array $fromversions list of all fromversions
+     * @param array<string, array<string, string>> $fromversions list of all fromversions
      * @param string $currentVersion current package version
      * @param string $newVersion new package version
-     * @return  array       list of update steps (old version => new version, old version => new version, ...)
+     * @return array<string, string> list of update steps (old version => new version, old version => new version, ...)
      * @throws  SystemException
      */
-    protected function findShortestUpdateThread($package, $fromversions, $currentVersion, $newVersion)
+    private function findShortestUpdateThread(string $package, array $fromversions, string $currentVersion, string $newVersion): array
     {
         if (!isset($fromversions[$newVersion])) {
             throw new UnknownUpdatePath($package, $currentVersion, $newVersion);
@@ -735,20 +735,19 @@ protected function findShortestUpdateThread($package, $fromversions, $currentVer
 
     /**
      * Compares the length of two updates threads.
+     *
+     * @param array<string, string> $updateThreadListA
+     * @param array<string, string> $updateThreadListB
      */
-    protected function compareUpdateThreadLists(array $updateThreadListA, array $updateThreadListB): int
+    private function compareUpdateThreadLists(array $updateThreadListA, array $updateThreadListB): int
     {
         return \count($updateThreadListA) <=> \count($updateThreadListB);
     }
 
     /**
      * Returns the filename of downloads stored in session or null if no stored downloads exist.
-     *
-     * @param string $package package identifier
-     * @param string $version package version
-     * @return  string|bool
      */
-    protected function getCachedDownload($package, $version)
+    private function getCachedDownload(string $package, string $version): string|bool
     {
         $cachedDownloads = WCF::getSession()->getVar('cachedPackageUpdateDownloads');
         if (isset($cachedDownloads[$package . '@' . $version]) && @\file_exists($cachedDownloads[$package . '@' . $version])) {
@@ -761,10 +760,10 @@ protected function getCachedDownload($package, $version)
     /**
      * Returns stored auth data the update server with given data.
      *
-     * @param array $data
-     * @return  array
+     * @param mixed[] $data
+     * @return string[]
      */
-    protected function getAuthData(array $data)
+    private function getAuthData(array $data): array
     {
         $updateServer = new PackageUpdateServer(null, $data);
 
diff --git a/wcfsetup/install/files/lib/system/package/PackageManifest.class.php b/wcfsetup/install/files/lib/system/package/PackageManifest.class.php
index 81b19a397bd..5b0a850bab7 100644
--- a/wcfsetup/install/files/lib/system/package/PackageManifest.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageManifest.class.php
@@ -15,6 +15,9 @@
  * @copyright   2001-2022 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   6.0
+ * @phpstan-import-type Instruction from PackageArchive
+ * @phpstan-import-type VoidInstruction from PackageArchive
+ * @phpstan-type CleanInstruction array{type: string, value: string, attributes: array<string, string>}|array{0: PackageArchive::VOID_MARKER}
  */
 final class PackageManifest
 {
@@ -120,6 +123,9 @@ private function getManifestV1(): string
         return $this->stringifyV1($manifest);
     }
 
+    /**
+     * @return array<string, string>
+     */
     private function getDisplayNames(): array
     {
         $displayNames = $this->archive->getPackageInfo('packageName');
@@ -128,6 +134,9 @@ private function getDisplayNames(): array
         return $displayNames;
     }
 
+    /**
+     * @return list<array{name: string, minversion: string}>
+     */
     private function getRequirements(): array
     {
         $requirements = $this->archive->getRequirements();
@@ -142,6 +151,9 @@ private function getRequirements(): array
         }, $requirements);
     }
 
+    /**
+     * @return list<array{name: string, version: string}>
+     */
     private function getExcludedPackages(): array
     {
         $exclusions = $this->archive->getExcludedPackages();
@@ -155,6 +167,10 @@ private function getExcludedPackages(): array
         }, $exclusions);
     }
 
+    /**
+     * @param string[] $ignore
+     * @return array<string, string>
+     */
     private function getFiles(array $ignore = []): array
     {
         $tar = $this->archive->getTar();
@@ -178,11 +194,17 @@ private function getFiles(array $ignore = []): array
         return $files;
     }
 
+    /**
+     * @return CleanInstruction[]
+     */
     private function getInstallInstructions(): array
     {
         return $this->cleanInstructions($this->archive->getInstallInstructions());
     }
 
+    /**
+     * @return array<string, CleanInstruction[]>
+     */
     private function getUpdateInstructions(): array
     {
         $updateInstructions = $this->archive->getAllUpdateInstructions();
@@ -191,11 +213,19 @@ private function getUpdateInstructions(): array
         return \array_map($this->cleanInstructions(...), $updateInstructions);
     }
 
+    /**
+     * @param array{name: string} $a
+     * @param array{name: string} $b
+     */
     private function compareByName(array $a, array $b): int
     {
         return $a['name'] <=> $b['name'];
     }
 
+    /**
+     * @param Instruction[]|array{0: VoidInstruction} $instructions
+     * @return CleanInstruction[]
+     */
     private function cleanInstructions(array $instructions): array
     {
         // Note: The $instructions array *must not* be sorted. The order
@@ -225,6 +255,7 @@ private function cleanInstructions(array $instructions): array
      * Attention: This method must not be modified. If a format change is required a
      * replacement method must be written.
      *
+     * @param mixed[]|string|int $data
      * @throws \UnexpectedValueException On non-representable data.
      */
     private function stringifyV1(array|string|int $data, int $depth = 0): string
diff --git a/wcfsetup/install/files/lib/system/package/PackageUninstallationDispatcher.class.php b/wcfsetup/install/files/lib/system/package/PackageUninstallationDispatcher.class.php
index f5e57ea3488..71b1a58028e 100644
--- a/wcfsetup/install/files/lib/system/package/PackageUninstallationDispatcher.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageUninstallationDispatcher.class.php
@@ -157,6 +157,7 @@ protected function executePIP(array $nodeData): PackageInstallationStep
     /**
      * Executes the package's uninstall script (if existing).
      *
+     * @return void
      * @since   3.0
      */
     protected function executeUninstallScript()
@@ -171,7 +172,7 @@ protected function executeUninstallScript()
     /**
      * Uninstalls current package.
      *
-     * @param array $nodeData
+     * @param mixed[] $nodeData
      */
     protected function uninstallPackage(array $nodeData): PackageInstallationStep
     {
@@ -199,6 +200,7 @@ protected function uninstallPackage(array $nodeData): PackageInstallationStep
      * @param string[] $files
      * @param bool $deleteEmptyDirectories
      * @param bool $deleteEmptyTargetDir
+     * @return void
      */
     public function deleteFiles($targetDir, $files, $deleteEmptyTargetDir = false, $deleteEmptyDirectories = true)
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageUninstallationNodeBuilder.class.php b/wcfsetup/install/files/lib/system/package/PackageUninstallationNodeBuilder.class.php
index efb25eccaf3..4cf420d3dcb 100644
--- a/wcfsetup/install/files/lib/system/package/PackageUninstallationNodeBuilder.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageUninstallationNodeBuilder.class.php
@@ -57,7 +57,7 @@ public function buildNodes()
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     protected function buildUninstallationPluginNodes()
     {
diff --git a/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php b/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
index e5cffb2ae44..88aa1c5feae 100644
--- a/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
@@ -28,11 +28,36 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @phpstan-type PackageInfo array{
+ *  author: string,
+ *  authorURL: string,
+ *  isApplication: int,
+ *  packageName: string,
+ *  packageDescription: string,
+ *  pluginStoreFileID: int,
+ *  versions: array<string, array{
+ *    compatibility?: list<string>,
+ *    excludedPackages?: array<string, array{version: string}>,
+ *    isAccessible: int,
+ *    file?: string,
+ *    fromversions?: list<string>,
+ *    license?: array{license: string, licenseURL: string},
+ *    optionalPackages?: list<string>,
+ *    packageDate: string,
+ *    requiredPackages?: array<string, array{minversion?: string}>,
+ *  }>,
+ * }
  */
 final class PackageUpdateDispatcher extends SingletonFactory
 {
     private bool $hasAuthCode = false;
 
+    /**
+     * @var array{
+     *  woltlab: array<string, string>,
+     *  pluginstore: array<string, string>,
+     * }
+     */
     private array $purchasedVersions = [
         'woltlab' => [],
         'pluginstore' => [],
@@ -43,7 +68,7 @@ final class PackageUpdateDispatcher extends SingletonFactory
      *
      * @param int[] $packageUpdateServerIDs
      */
-    public function refreshPackageDatabase(array $packageUpdateServerIDs = [], bool $ignoreCache = false)
+    public function refreshPackageDatabase(array $packageUpdateServerIDs = [], bool $ignoreCache = false): void
     {
         // get update server data
         $tmp = PackageUpdateServer::getActiveUpdateServers($packageUpdateServerIDs);
@@ -62,7 +87,7 @@ public function refreshPackageDatabase(array $packageUpdateServerIDs = [], bool
         }
 
         if ($requirePurchasedVersions && PACKAGE_SERVER_AUTH_CODE) {
-            $this->getPurchasedVersions();
+            $this->fetchPurchasedVersions();
         }
 
         // loop servers
@@ -71,7 +96,7 @@ public function refreshPackageDatabase(array $packageUpdateServerIDs = [], bool
             $errorMessage = '';
 
             try {
-                $this->getPackageUpdateXML($updateServer);
+                $this->fetchPackageUpdateXML($updateServer);
                 $refreshedPackageLists = true;
             } catch (SystemException $e) {
                 $errorMessage = $e->getMessage();
@@ -108,7 +133,7 @@ public function refreshPackageDatabase(array $packageUpdateServerIDs = [], bool
         }
     }
 
-    private function getPurchasedVersions()
+    private function fetchPurchasedVersions(): void
     {
         $client = HttpFactory::makeClientWithTimeout(5);
         $request = new Request(
@@ -145,7 +170,7 @@ private function getPurchasedVersions()
      * @throws  PackageUpdateUnauthorizedException
      * @throws  SystemException
      */
-    private function getPackageUpdateXML(PackageUpdateServer $updateServer)
+    private function fetchPackageUpdateXML(PackageUpdateServer $updateServer): void
     {
         $authData = $updateServer->getAuthData();
         $options = [];
@@ -270,7 +295,8 @@ private function getPackageUpdateXML(PackageUpdateServer $updateServer)
     /**
      * Parses a stream containing info from a packages_update.xml.
      *
-     * @throws      SystemException
+     * @return array<string, PackageInfo>
+     * @throws SystemException
      */
     private function parsePackageUpdateXML(PackageUpdateServer $updateServer, string $content, string $apiVersion): array
     {
@@ -308,7 +334,8 @@ private function parsePackageUpdateXML(PackageUpdateServer $updateServer, string
     /**
      * Parses the xml structure from a packages_update.xml.
      *
-     * @throws      PackageValidationException
+     * @return PackageInfo
+     * @throws  PackageValidationException
      */
     private function parsePackageUpdateXMLBlock(
         PackageUpdateServer $updateServer,
@@ -332,20 +359,20 @@ private function parsePackageUpdateXMLBlock(
             \assert($element instanceof \DOMElement);
             switch ($element->tagName) {
                 case 'packagename':
-                    $packageInfo['packageName'] = $element->nodeValue;
+                    $packageInfo['packageName'] = $element->textContent;
                     break;
 
                 case 'packagedescription':
-                    $packageInfo['packageDescription'] = $element->nodeValue;
+                    $packageInfo['packageDescription'] = $element->textContent;
                     break;
 
                 case 'isapplication':
-                    $packageInfo['isApplication'] = \intval($element->nodeValue);
+                    $packageInfo['isApplication'] = \intval($element->textContent);
                     break;
 
                 case 'pluginStoreFileID':
                     if ($updateServer->isWoltLabStoreServer()) {
-                        $packageInfo['pluginStoreFileID'] = \intval($element->nodeValue);
+                        $packageInfo['pluginStoreFileID'] = \intval($element->textContent);
                     }
                     break;
             }
@@ -357,11 +384,11 @@ private function parsePackageUpdateXMLBlock(
             \assert($element instanceof \DOMElement);
             switch ($element->tagName) {
                 case 'author':
-                    $packageInfo['author'] = $element->nodeValue;
+                    $packageInfo['author'] = $element->textContent;
                     break;
 
                 case 'authorurl':
-                    $packageInfo['authorURL'] = $element->nodeValue;
+                    $packageInfo['authorURL'] = $element->textContent;
                     break;
             }
         }
@@ -408,16 +435,16 @@ private function parsePackageUpdateXMLBlock(
                     case 'fromversions':
                         $fromversions = $xpath->query('child::*', $child);
                         foreach ($fromversions as $fromversion) {
-                            $packageInfo['versions'][$versionNo]['fromversions'][] = $fromversion->nodeValue;
+                            $packageInfo['versions'][$versionNo]['fromversions'][] = $fromversion->textContent;
                         }
                         break;
 
                     case 'timestamp':
-                        $packageInfo['versions'][$versionNo]['packageDate'] = $child->nodeValue;
+                        $packageInfo['versions'][$versionNo]['packageDate'] = $child->textContent;
                         break;
 
                     case 'file':
-                        $packageInfo['versions'][$versionNo]['file'] = $child->nodeValue;
+                        $packageInfo['versions'][$versionNo]['file'] = $child->textContent;
                         break;
 
                     case 'requiredpackages':
@@ -426,7 +453,7 @@ private function parsePackageUpdateXMLBlock(
                         /** @var \DOMElement $requiredPackage */
                         foreach ($requiredPackages as $requiredPackage) {
                             $minVersion = $requiredPackage->getAttribute('minversion');
-                            $required = $requiredPackage->nodeValue;
+                            $required = $requiredPackage->textContent;
 
                             $packageInfo['versions'][$versionNo]['requiredPackages'][$required] = [];
                             if (!empty($minVersion)) {
@@ -440,7 +467,7 @@ private function parsePackageUpdateXMLBlock(
 
                         $optionalPackages = $xpath->query('child::*', $child);
                         foreach ($optionalPackages as $optionalPackage) {
-                            $packageInfo['versions'][$versionNo]['optionalPackages'][] = $optionalPackage->nodeValue;
+                            $packageInfo['versions'][$versionNo]['optionalPackages'][] = $optionalPackage->textContent;
                         }
                         break;
 
@@ -448,7 +475,7 @@ private function parsePackageUpdateXMLBlock(
                         $excludedpackages = $xpath->query('child::*', $child);
                         /** @var \DOMElement $excludedPackage */
                         foreach ($excludedpackages as $excludedPackage) {
-                            $exclusion = $excludedPackage->nodeValue;
+                            $exclusion = $excludedPackage->textContent;
                             $version = $excludedPackage->getAttribute('version');
 
                             $packageInfo['versions'][$versionNo]['excludedPackages'][$exclusion] = [
@@ -459,7 +486,7 @@ private function parsePackageUpdateXMLBlock(
 
                     case 'license':
                         $packageInfo['versions'][$versionNo]['license'] = [
-                            'license' => $child->nodeValue,
+                            'license' => $child->textContent,
                             'licenseURL' => $child->hasAttribute('url') ? $child->getAttribute('url') : '',
                         ];
                         break;
@@ -499,6 +526,8 @@ private function parsePackageUpdateXMLBlock(
 
     /**
      * Updates information parsed from a packages_update.xml into the database.
+     *
+     * @param array<string, PackageInfo> $allNewPackages
      */
     private function savePackageUpdates(array $allNewPackages, int $packageUpdateServerID): void
     {
@@ -610,9 +639,9 @@ private function savePackageUpdates(array $allNewPackages, int $packageUpdateSer
                     $coreExclude = null;
                     $versionData['excludedPackages'] = \array_filter(
                         $versionData['excludedPackages'],
-                        static function ($excludedPackage, $excludedVersion) use (&$coreExclude) {
+                        static function ($excludedVersion, $excludedPackage) use (&$coreExclude) {
                             if ($excludedPackage === 'com.woltlab.wcf') {
-                                $coreExclude = $excludedVersion;
+                                $coreExclude = $excludedVersion['version'];
 
                                 return false;
                             }
@@ -678,8 +707,8 @@ static function ($excludedPackage, $excludedVersion) use (&$coreExclude) {
     /**
      * Returns a list of available updates for installed packages.
      *
-     * @return  array
-     * @throws      SystemException
+     * @return mixed[]
+     * @throws SystemException
      */
     public function getAvailableUpdates(bool $removeRequirements = true, bool $removeOlderMinorReleases = false): array
     {
@@ -702,6 +731,7 @@ public function getAvailableUpdates(bool $removeRequirements = true, bool $remov
         while ($row = $statement->fetchArray()) {
             $existingPackages[$row['package']][] = $row;
         }
+
         if (empty($existingPackages)) {
             return $updates;
         }
@@ -813,6 +843,9 @@ public function getAvailableUpdates(bool $removeRequirements = true, bool $remov
 
     /**
      * Removes unnecessary updates of requirements from the list of available updates.
+     *
+     * @param mixed[] $updates
+     * @return mixed[]
      */
     private function removeUpdateRequirements(array $updates, int $packageUpdateVersionID): array
     {
@@ -847,6 +880,7 @@ private function removeUpdateRequirements(array $updates, int $packageUpdateVers
     /**
      * Returns package update versions of the specified package.
      *
+     * @return mixed[]
      * @throws  SystemException
      */
     public function getPackageUpdateVersions(string $package, string $version = ''): array
diff --git a/wcfsetup/install/files/lib/system/package/command/RebuildBootstrapper.class.php b/wcfsetup/install/files/lib/system/package/command/RebuildBootstrapper.class.php
index 4644ef31181..d6fc9ccf537 100644
--- a/wcfsetup/install/files/lib/system/package/command/RebuildBootstrapper.class.php
+++ b/wcfsetup/install/files/lib/system/package/command/RebuildBootstrapper.class.php
@@ -17,7 +17,7 @@
  */
 final class RebuildBootstrapper
 {
-    public function __invoke()
+    public function __invoke(): void
     {
         $groups = PackageList::getTopologicallySortedPackages();
 
@@ -80,7 +80,7 @@ private function bootstrapExists(Package $package): bool
         return \file_exists($this->getBootstrapFilename($package));
     }
 
-    private function getBootstrapFilename(Package $package)
+    private function getBootstrapFilename(Package $package): string
     {
         return \WCF_DIR . 'lib/' . $this->getRelativeBootstrapFilename($package);
     }
diff --git a/wcfsetup/install/files/lib/system/package/license/LicenseApi.class.php b/wcfsetup/install/files/lib/system/package/license/LicenseApi.class.php
index 8bc0ca8a519..b024496bf89 100644
--- a/wcfsetup/install/files/lib/system/package/license/LicenseApi.class.php
+++ b/wcfsetup/install/files/lib/system/package/license/LicenseApi.class.php
@@ -53,6 +53,9 @@ private static function parseLicenseData(string $json): LicenseData
         }
     }
 
+    /**
+     * @param array{}|array{username: string, password: string} $authData
+     */
     public static function fetchFromRemote(array $authData = []): LicenseData
     {
         if ($authData === []) {
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ACLOptionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ACLOptionPackageInstallationPlugin.class.php
index e74261d3ae9..40cbda283ca 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ACLOptionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ACLOptionPackageInstallationPlugin.class.php
@@ -357,6 +357,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -529,6 +530,8 @@ public function getEntryTypes()
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -571,6 +574,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -591,6 +595,7 @@ protected function getXsdFilename()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -603,6 +608,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -639,6 +645,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -655,6 +662,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php
index d4cea4e95b3..d7ce92f572a 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ACPMenuPackageInstallationPlugin.class.php
@@ -78,6 +78,7 @@ protected function getXsdFilename()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -162,6 +163,8 @@ static function (TextFormField $formField) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -187,6 +190,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ACPSearchProviderPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ACPSearchProviderPackageInstallationPlugin.class.php
index feade637c6d..42789f0e3aa 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ACPSearchProviderPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ACPSearchProviderPackageInstallationPlugin.class.php
@@ -130,6 +130,8 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -152,6 +154,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -161,6 +164,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     protected function getXsdFilename()
@@ -170,6 +174,7 @@ protected function getXsdFilename()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -226,6 +231,7 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -238,6 +244,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ACPTemplatePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ACPTemplatePackageInstallationPlugin.class.php
index ed90f9471cc..a6a1b6b0f56 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ACPTemplatePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ACPTemplatePackageInstallationPlugin.class.php
@@ -79,6 +79,7 @@ public function uninstall()
 
         \assert($this->installation instanceof PackageUninstallationDispatcher);
         foreach ($templates as $application => $templateNames) {
+            // @phpstan-ignore method.notFound
             $this->installation->deleteFiles(
                 Application::getDirectory($application),
                 $templateNames,
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractFileDeletePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractFileDeletePackageInstallationPlugin.class.php
index 516fd482589..41ed7ef5b5e 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractFileDeletePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractFileDeletePackageInstallationPlugin.class.php
@@ -233,6 +233,7 @@ protected function getFileFieldDescription(): ?string
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function addFormFields(IFormDocument $form)
     {
@@ -268,6 +269,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
     {
@@ -280,6 +283,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      */
     public function getElementIdentifier(\DOMElement $element)
     {
@@ -290,6 +294,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
     {
@@ -301,6 +306,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
     {
@@ -317,6 +323,7 @@ protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
     {
@@ -334,13 +341,14 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
     /**
      * @inheritDoc
      */
-    final protected function prepareDeleteXmlElement(\DOMElement $element)
+    final protected function prepareDeleteXmlElement(\DOMElement $element): null
     {
         return null;
     }
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement = null)
     {
@@ -374,6 +382,7 @@ protected function getImportElements(\DOMXPath $xpath)
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected function getEmptyXml()
     {
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractMenuPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractMenuPackageInstallationPlugin.class.php
index b2d9e096402..b47175344b0 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractMenuPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractMenuPackageInstallationPlugin.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\package\plugin;
 
 use wcf\data\acp\menu\item\ACPMenuItem;
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\page\IPage;
 use wcf\system\devtools\pip\IDevtoolsPipEntryList;
@@ -129,6 +130,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -148,7 +150,7 @@ protected function addFormFields(IFormDocument $form)
                         // replace `Editor` with `List`
                         $listClassName = \substr($this->className, 0, -6) . 'List';
 
-                        /** @var DatabaseObjectList $menuItemList */
+                        /** @var DatabaseObjectList<DatabaseObject> $menuItemList */
                         $menuItemList = new $listClassName();
                         $menuItemList->getConditionBuilder()->add('menuItem = ?', [$formField->getValue()]);
 
@@ -327,6 +329,8 @@ function (SingleSelectionFormField $formField) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -389,6 +393,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -399,14 +404,17 @@ public function getElementIdentifier(\DOMElement $element)
     /**
      * Returns data on the structure of the menu.
      *
-     * @return  array
+     * @return array{
+     *  levels: array<string, int>,
+     *  structure: array<string, array<string, ACPMenuItem>>
+     * }
      */
     protected function getMenuStructureData()
     {
         // replace `Editor` with `List`
         $listClassName = \substr($this->className, 0, -6) . 'List';
 
-        /** @var DatabaseObjectList $menuItemList */
+        /** @var DatabaseObjectList<DatabaseObject> $menuItemList */
         $menuItemList = new $listClassName();
         $menuItemList->getConditionBuilder()->add('packageID IN (?)', [
             \array_merge(
@@ -419,10 +427,11 @@ protected function getMenuStructureData()
 
         // for better IDE auto-completion, we use `ACPMenuItem`, but the
         // menu items can also belong to other menus
-        /** @var ACPMenuItem[] $menuItems */
+        /** @var array<string, ACPMenuItem> $menuItems */
         $menuItems = [];
-        /** @var ACPMenuItem[][] $menuStructure */
+        /** @var array<string, array<string, ACPMenuItem>> $menuStructure */
         $menuStructure = [];
+        /** @var ACPMenuItem $menuItem */
         foreach ($menuItemList as $menuItem) {
             if (!isset($menuStructure[$menuItem->parentMenuItem])) {
                 $menuStructure[$menuItem->parentMenuItem] = [];
@@ -432,6 +441,7 @@ protected function getMenuStructureData()
             $menuItems[$menuItem->menuItem] = $menuItem;
         }
 
+        /** @var array<string, int> $menuItemLevels */
         $menuItemLevels = [];
         foreach ($menuStructure as $parentMenuItemName => $childMenuItems) {
             $menuItemsLevel = 1;
@@ -454,6 +464,7 @@ protected function getMenuStructureData()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -466,6 +477,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractOptionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractOptionPackageInstallationPlugin.class.php
index d37f2e29364..43f887ce31c 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractOptionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractOptionPackageInstallationPlugin.class.php
@@ -173,6 +173,7 @@ protected function deleteItems(\DOMXPath $xpath)
      * Imports option categories.
      *
      * @param \DOMXPath $xpath
+     * @return void
      * @throws  SystemException
      */
     protected function importCategories(\DOMXPath $xpath)
@@ -231,6 +232,7 @@ protected function importCategories(\DOMXPath $xpath)
      * Imports options.
      *
      * @param \DOMXPath $xpath
+     * @return void
      */
     protected function importOptions(\DOMXPath $xpath)
     {
@@ -286,7 +288,7 @@ public function uninstall()
      * Returns the category with given name.
      *
      * @param string $category
-     * @return      array|false
+     * @return array{categoryID: int, packageID: int}|false
      */
     protected function getExistingCategory($category)
     {
@@ -304,7 +306,8 @@ protected function getExistingCategory($category)
     /**
      * Installs option categories.
      *
-     * @param array $category
+     * @param array<string, string|int|null> $category
+     * @return void
      * @throws  SystemException
      */
     protected function saveCategory($category)
@@ -362,14 +365,16 @@ protected function saveCategory($category)
     /**
      * Installs options.
      *
-     * @param array $option
+     * @param array<string, int|string> $option
      * @param string $categoryName
      * @param int $existingOptionID
+     * @return void
      */
     abstract protected function saveOption($option, $categoryName, $existingOptionID = 0);
 
     /**
-     * @inheritDoc
+     * @param array{name: string} $data
+     * @return void
      */
     protected function validateOption(array $data)
     {
@@ -429,6 +434,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -746,6 +752,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -900,6 +908,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -909,6 +918,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return list<string>
      * @since   5.2
      */
     public function getEntryTypes()
@@ -970,6 +980,7 @@ protected function getSortOptionHandler()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement = null)
@@ -997,6 +1008,7 @@ protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -1024,6 +1036,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -1083,6 +1096,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
@@ -1130,7 +1144,7 @@ protected function insertNewXmlElement(XML $xml, \DOMElement $newElement)
     /**
      * Returns the options for the option type form field.
      *
-     * @return  array
+     * @return  string[]
      * @since   5.2
      */
     protected function getOptionTypeOptions()
@@ -1203,6 +1217,7 @@ protected function getOptionTypeOptions()
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -1221,6 +1236,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
@@ -1266,6 +1282,7 @@ protected function deleteObject(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addDeleteElement(\DOMElement $element)
@@ -1301,6 +1318,7 @@ protected function addDeleteElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return bool
      * @since   5.2
      */
     protected function sanitizeXmlFileAfterDeleteEntry(\DOMDocument $document)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractPackageInstallationPlugin.class.php
index b76888ef2a7..b78e53ca5b1 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractPackageInstallationPlugin.class.php
@@ -36,7 +36,7 @@ abstract class AbstractPackageInstallationPlugin implements IPackageInstallation
 
     /**
      * install/update instructions
-     * @var array
+     * @var mixed[]
      */
     public $instruction = [];
 
@@ -44,7 +44,7 @@ abstract class AbstractPackageInstallationPlugin implements IPackageInstallation
      * Creates a new AbstractPackageInstallationPlugin object.
      *
      * @param PackageInstallationDispatcher $installation
-     * @param array $instruction
+     * @param mixed[] $instruction
      */
     public function __construct(PackageInstallationDispatcher $installation, $instruction = [])
     {
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractTemplateDeletePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractTemplateDeletePackageInstallationPlugin.class.php
index 066a15e9f73..88349a64724 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractTemplateDeletePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractTemplateDeletePackageInstallationPlugin.class.php
@@ -32,6 +32,7 @@ protected function getFilenameTableColumn(): string
 
     /**
      * @inheritDoc
+     * @return void
      */
     protected function addFormFields(IFormDocument $form)
     {
diff --git a/wcfsetup/install/files/lib/system/package/plugin/AbstractXMLPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/AbstractXMLPackageInstallationPlugin.class.php
index 2846343ef2d..31fdb60cad0 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/AbstractXMLPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/AbstractXMLPackageInstallationPlugin.class.php
@@ -89,6 +89,7 @@ public function uninstall()
      * Deletes items.
      *
      * @param \DOMXPath $xpath
+     * @return void
      */
     protected function deleteItems(\DOMXPath $xpath)
     {
@@ -125,7 +126,7 @@ protected function deleteItems(\DOMXPath $xpath)
 
     /**
      * @param \DOMXPath $xpath
-     * @return  \DOMNodeList
+     * @return  \DOMNodeList<\DOMElement>
      */
     protected function getImportElements(\DOMXPath $xpath)
     {
@@ -136,6 +137,7 @@ protected function getImportElements(\DOMXPath $xpath)
      * Imports or updates items.
      *
      * @param \DOMXPath $xpath
+     * @return void
      */
     protected function importItems(\DOMXPath $xpath)
     {
@@ -218,8 +220,9 @@ protected function importItems(\DOMXPath $xpath)
      * Sets element value from XPath.
      *
      * @param \DOMXPath $xpath
-     * @param array $elements
+     * @param array<string, mixed> $elements
      * @param \DOMElement $element
+     * @return void
      */
     protected function getElement(\DOMXPath $xpath, array &$elements, \DOMElement $element)
     {
@@ -285,8 +288,8 @@ protected function getI18nValues(array $values, $singleValueOnly = false)
     /**
      * Inserts or updates new items.
      *
-     * @param array $row
-     * @param array $data
+     * @param array<string, mixed> $row
+     * @param array<string, mixed> $data
      * @return  \wcf\data\IStorableObject|\wcf\data\DatabaseObjectEditor|null
      */
     protected function import(array $row, array $data)
@@ -300,7 +303,7 @@ protected function import(array $row, array $data)
             // update existing item
             $baseClass = \call_user_func([$this->className, 'getBaseClass']);
 
-            /** @var \wcf\data\DatabaseObjectEditor $itemEditor */
+            /** @var \wcf\data\DatabaseObjectEditor<\wcf\data\DatabaseObject> $itemEditor */
             $itemEditor = new $this->className(new $baseClass(null, $row));
             $itemEditor->update($data);
 
@@ -311,13 +314,16 @@ protected function import(array $row, array $data)
     /**
      * Executed after all items would have been imported, use this hook if you've
      * overwritten import() to disable insert/update.
+     *
+     * @return void
      */
     protected function postImport() {}
 
     /**
      * Deletes the given items.
      *
-     * @param array $items
+     * @param mixed[] $items
+     * @return void
      */
     abstract protected function handleDelete(array $items);
 
@@ -325,8 +331,8 @@ abstract protected function handleDelete(array $items);
      * Prepares import, use this to map xml tags and attributes
      * to their corresponding database fields.
      *
-     * @param array $data
-     * @return  array
+     * @param mixed[] $data
+     * @return mixed[]
      */
     abstract protected function prepareImport(array $data);
 
@@ -334,7 +340,8 @@ abstract protected function prepareImport(array $data);
      * Validates given item, e.g. checking for invalid values. If validation
      * fails you should throw an exception.
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return void
      */
     protected function validateImport(array $data) {}
 
@@ -342,8 +349,8 @@ protected function validateImport(array $data) {}
      * Returns an array with a sql query and its parameters to find an existing item for updating
      * or `null` if updates are not supported.
      *
-     * @param array $data
-     * @return  array|null
+     * @param mixed[] $data
+     * @return mixed[]|null
      */
     abstract protected function findExistingItem(array $data);
 
@@ -353,7 +360,8 @@ abstract protected function findExistingItem(array $data);
      *
      * Attention: $data is passed by reference
      *
-     * @param array $data
+     * @param mixed[] $data
+     * @return void
      */
     protected function prepareCreate(array &$data)
     {
@@ -362,6 +370,8 @@ protected function prepareCreate(array &$data)
 
     /**
      * Triggered after executing all delete and/or import actions.
+     *
+     * @return void
      */
     protected function cleanup() {}
 
diff --git a/wcfsetup/install/files/lib/system/package/plugin/BBCodePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/BBCodePackageInstallationPlugin.class.php
index 2d6a5932a5c..314899b99a7 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/BBCodePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/BBCodePackageInstallationPlugin.class.php
@@ -260,6 +260,8 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -335,6 +337,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -344,6 +347,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     protected function getXsdFilename()
@@ -353,6 +357,7 @@ protected function getXsdFilename()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -531,6 +536,7 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -544,6 +550,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/BoxPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/BoxPackageInstallationPlugin.class.php
index f3a3038506b..e0bb7edbe89 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/BoxPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/BoxPackageInstallationPlugin.class.php
@@ -5,6 +5,8 @@
 use wcf\data\box\Box;
 use wcf\data\box\BoxEditor;
 use wcf\data\box\BoxList;
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\data\page\PageNode;
 use wcf\data\page\PageNodeTree;
@@ -61,7 +63,7 @@ class BoxPackageInstallationPlugin extends AbstractXMLPackageInstallationPlugin
 
     /**
      * box contents
-     * @var array
+     * @var array<int, array<string, array{content?: string, title: string}>>
      */
     protected $content = [];
 
@@ -498,6 +500,7 @@ public function getAdditionalTemplateCode()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -644,7 +647,7 @@ protected function addFormFields(IFormDocument $form)
         // add box controller-specific form fields
         foreach (ObjectTypeCache::getInstance()->getObjectTypes('com.woltlab.wcf.boxController') as $objectType) {
             if (\is_subclass_of($objectType->className, AbstractDatabaseObjectListBoxController::class)) {
-                /** @var AbstractDatabaseObjectListBoxController $boxController */
+                /** @var AbstractDatabaseObjectListBoxController<DatabaseObjectList<DatabaseObject>> $boxController */
                 $boxController = new $objectType->className();
 
                 $boxController->addPipGuiFormFields($form, $objectType->objectType);
@@ -654,6 +657,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -733,7 +738,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
                     AbstractDatabaseObjectListBoxController::class
                 )
             ) {
-                /** @var AbstractDatabaseObjectListBoxController $boxController */
+                /** @var AbstractDatabaseObjectListBoxController<DatabaseObjectList<DatabaseObject>> $boxController */
                 $boxController = new $objectType->className();
 
                 $objectTypeData = $boxController->getPipGuiElementData($element, $saveData);
@@ -816,6 +821,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -825,6 +831,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -837,6 +844,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -935,7 +943,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
                     AbstractDatabaseObjectListBoxController::class
                 )
             ) {
-                /** @var AbstractDatabaseObjectListBoxController $boxController */
+                /** @var AbstractDatabaseObjectListBoxController<DatabaseObjectList<DatabaseObject>> $boxController */
                 $boxController = new $objectType->className();
 
                 $boxController->writePipGuiEntry($box, $form);
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ClipboardActionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ClipboardActionPackageInstallationPlugin.class.php
index bf71f8848d6..c5a23929411 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ClipboardActionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ClipboardActionPackageInstallationPlugin.class.php
@@ -187,6 +187,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -263,6 +264,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, mixed>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -299,6 +302,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -311,6 +315,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -323,6 +328,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -354,6 +360,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -371,6 +378,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/CoreObjectPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/CoreObjectPackageInstallationPlugin.class.php
index 44fc8716c1b..a3565380de3 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/CoreObjectPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/CoreObjectPackageInstallationPlugin.class.php
@@ -99,6 +99,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -139,6 +140,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -151,6 +154,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -160,6 +164,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -171,6 +176,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -184,6 +190,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -199,6 +206,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/CronjobPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/CronjobPackageInstallationPlugin.class.php
index 182afa863e4..4f3067b1127 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/CronjobPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/CronjobPackageInstallationPlugin.class.php
@@ -236,6 +236,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -324,6 +325,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, mixed>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -443,6 +446,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -452,6 +456,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -464,6 +469,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/EventListenerPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/EventListenerPackageInstallationPlugin.class.php
index 36994e3e483..f4e30c86840 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/EventListenerPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/EventListenerPackageInstallationPlugin.class.php
@@ -171,6 +171,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -346,6 +347,8 @@ public function editEntry(IFormDocument $form, $identifier)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -398,6 +401,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -407,6 +411,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -420,6 +425,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/FilePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/FilePackageInstallationPlugin.class.php
index 2425f7701aa..bf1ef0d3ddf 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/FilePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/FilePackageInstallationPlugin.class.php
@@ -105,6 +105,7 @@ public function uninstall()
 
         \assert($this->installation instanceof PackageUninstallationDispatcher);
         foreach ($files as $application => $filenames) {
+            // @phpstan-ignore method.notFound
             $this->installation->deleteFiles(Application::getDirectory($application), $filenames);
 
             // delete log entries
diff --git a/wcfsetup/install/files/lib/system/package/plugin/IPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/IPackageInstallationPlugin.class.php
index 97618f10ce1..b49eabde8fb 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/IPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/IPackageInstallationPlugin.class.php
@@ -15,11 +15,15 @@ interface IPackageInstallationPlugin
 {
     /**
      * Executes the installation of this plugin.
+     *
+     * @return mixed
      */
     public function install();
 
     /**
      * Executes the update of this plugin.
+     *
+     * @return mixed
      */
     public function update();
 
@@ -33,6 +37,8 @@ public function hasUninstall();
 
     /**
      * Executes the uninstallation of this plugin.
+     *
+     * @return void
      */
     public function uninstall();
 
diff --git a/wcfsetup/install/files/lib/system/package/plugin/IUniqueNameXMLPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/IUniqueNameXMLPackageInstallationPlugin.class.php
index 92f9509f8f7..049174c8363 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/IUniqueNameXMLPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/IUniqueNameXMLPackageInstallationPlugin.class.php
@@ -15,6 +15,8 @@ interface IUniqueNameXMLPackageInstallationPlugin
 {
     /**
      * Returns the name of an element by the given data.
+     *
+     * @param mixed[] $data
      */
     public function getNameByData(array $data): string;
 }
diff --git a/wcfsetup/install/files/lib/system/package/plugin/LanguagePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/LanguagePackageInstallationPlugin.class.php
index f6db33c1f6b..824d3f67ed3 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/LanguagePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/LanguagePackageInstallationPlugin.class.php
@@ -242,8 +242,9 @@ protected function readLanguage($filename)
      * Deletes categories which where changed by an update or uninstallation
      * in case they are now empty.
      *
-     * @param array $categoryIDs
+     * @param int[] $categoryIDs
      * @param int $packageID
+     * @return void
      */
     protected function deleteEmptyCategories(array $categoryIDs, $packageID)
     {
@@ -341,6 +342,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -516,6 +518,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -560,6 +564,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -629,6 +634,8 @@ protected function getImportElements(\DOMXPath $xpath)
 
     /**
      * @inheritDoc
+     * @param string $languageCode
+     * @return string
      * @since   5.2
      */
     protected function getEmptyXml($languageCode)
@@ -694,6 +701,7 @@ protected function getProjectXmls($createXmlFiles = false)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement = null)
@@ -748,6 +756,7 @@ protected function saveObject(\DOMElement $newElement, ?\DOMElement $oldElement
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -766,6 +775,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -844,6 +854,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function createAndInsertNewXmlElement(XML $xml, IFormDocument $form)
@@ -853,6 +864,8 @@ protected function createAndInsertNewXmlElement(XML $xml, IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param string $identifier
+     * @return \DOMElement
      * @since   5.2
      */
     protected function replaceXmlElement(XML $xml, IFormDocument $form, $identifier)
@@ -874,6 +887,7 @@ protected function replaceXmlElement(XML $xml, IFormDocument $form, $identifier)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
@@ -890,6 +904,7 @@ protected function deleteObject(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return bool
      * @since   5.2
      */
     protected function sanitizeXmlFileAfterDeleteEntry(\DOMDocument $document)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/MediaProviderPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/MediaProviderPackageInstallationPlugin.class.php
index b10cec72ed5..5204a1a572e 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/MediaProviderPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/MediaProviderPackageInstallationPlugin.class.php
@@ -123,6 +123,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -221,6 +222,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -251,6 +254,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -260,6 +264,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -272,6 +277,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/MenuItemPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/MenuItemPackageInstallationPlugin.class.php
index f2a193474c9..2b3376bd520 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/MenuItemPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/MenuItemPackageInstallationPlugin.class.php
@@ -286,6 +286,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -450,6 +451,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -538,6 +541,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -547,6 +551,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -559,6 +564,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/MenuPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/MenuPackageInstallationPlugin.class.php
index fb53237dcaf..5ef1e085d0b 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/MenuPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/MenuPackageInstallationPlugin.class.php
@@ -46,7 +46,7 @@ class MenuPackageInstallationPlugin extends AbstractXMLPackageInstallationPlugin
 
     /**
      * box meta data per menu
-     * @var array
+     * @var array<string, mixed>
      */
     public $boxData = [];
 
@@ -337,6 +337,7 @@ public function getAdditionalTemplateCode()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -443,6 +444,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -538,6 +541,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -547,6 +551,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -558,6 +563,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ObjectTypeDefinitionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ObjectTypeDefinitionPackageInstallationPlugin.class.php
index ab36011efba..d2fbe9e0e44 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ObjectTypeDefinitionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ObjectTypeDefinitionPackageInstallationPlugin.class.php
@@ -103,6 +103,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -167,6 +168,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -188,6 +191,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -197,6 +201,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -209,6 +214,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -229,6 +235,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -244,6 +251,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ObjectTypePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ObjectTypePackageInstallationPlugin.class.php
index a40aecd200c..78b3b5e63c7 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ObjectTypePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ObjectTypePackageInstallationPlugin.class.php
@@ -81,7 +81,7 @@ class ObjectTypePackageInstallationPlugin extends AbstractXMLPackageInstallation
 
     /**
      * data for object type definition-specific xml element children
-     * @var array
+     * @var array<string, mixed>
      */
     public $definitionElementChildren = [];
 
@@ -212,6 +212,8 @@ public function getAdditionalTemplateCode()
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -249,6 +251,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -837,6 +840,7 @@ static function (UserGroupOptionFormField $formField) {
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -872,6 +876,7 @@ public function getEntryList()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -917,6 +922,7 @@ public function getObjectTypeDefinitionDataContainer(IFormDocument $form, $defin
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -951,6 +957,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
      *
      * @param IFormDocument $form
      * @param string $objectTypeDefinition
+     * @return void
      */
     public function addBulkProcessingActionFields(IFormDocument $form, $objectTypeDefinition)
     {
@@ -1007,6 +1014,7 @@ public function addBulkProcessingActionFields(IFormDocument $form, $objectTypeDe
      * @param string $objectTypeDefinition
      * @param bool $addConditionObject
      * @param bool $addConditionGroup
+     * @return void
      * @since   5.2
      */
     public function addConditionFields(
@@ -1086,6 +1094,7 @@ public function addConditionFields(
         }
 
         $className = $dataContainer->getDocument()->getFormField('className');
+        \assert($className instanceof TextFormField);
         // `UserGroupCondition`
         $dataContainer->appendChild(
             BooleanFormField::create($prefix . 'UserGroupIncludeGuests')
@@ -1250,6 +1259,7 @@ public function setEntryData($identifier, IFormDocument $document)
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -1270,6 +1280,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/OptionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/OptionPackageInstallationPlugin.class.php
index 8d483572277..25c3ac19ac0 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/OptionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/OptionPackageInstallationPlugin.class.php
@@ -179,6 +179,7 @@ protected function saveOption($option, $categoryName, $existingOptionID = 0)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -317,6 +318,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -346,11 +349,11 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
-     * @since   5.2
+     * @return OptionHandler<Option, OptionCategory>
+     * @since 5.2
      */
     protected function getSortOptionHandler()
     {
-        // reuse OptionHandler
         return new class(true) extends OptionHandler {
             /**
              * @inheritDoc
@@ -383,6 +386,7 @@ public function getCategoryOptions($categoryName = '', $inherit = true)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/PIPPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/PIPPackageInstallationPlugin.class.php
index 66b582f0625..57f711ec8e9 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/PIPPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/PIPPackageInstallationPlugin.class.php
@@ -104,6 +104,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -154,6 +155,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -167,6 +170,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -176,6 +180,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -188,6 +193,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/PagePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/PagePackageInstallationPlugin.class.php
index b1e7fc32233..223fb9aebdf 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/PagePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/PagePackageInstallationPlugin.class.php
@@ -437,6 +437,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -643,6 +644,8 @@ static function (SingleSelectionFormField $formField) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -794,6 +797,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -803,6 +807,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -815,6 +820,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/SQLPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/SQLPackageInstallationPlugin.class.php
index a67a751ef09..1c0ab3d19bb 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/SQLPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/SQLPackageInstallationPlugin.class.php
@@ -41,29 +41,14 @@ public function install()
                 $this->installation->getAction()
             );
             $conflicts = $parser->test();
-            if (!empty($conflicts) && (isset($conflicts['CREATE TABLE']) || isset($conflicts['DROP TABLE']))) {
-                $unknownCreateTable = $conflicts['CREATE TABLE'] ?? [];
-                $unknownDropTable = $conflicts['DROP TABLE'] ?? [];
-
-                $errorMessage = "Can't";
-                if (!empty($unknownDropTable)) {
-                    $errorMessage .= " drop unknown table";
-                    if (\count($unknownDropTable) > 1) {
-                        $errorMessage .= "s";
-                    }
-                    $errorMessage .= " '" . \implode("', '", $unknownDropTable) . "'";
-                }
-                if (!empty($unknownCreateTable)) {
-                    if (!empty($unknownDropTable)) {
-                        $errorMessage .= " and can't";
-                    }
+            if ($conflicts !== [] && isset($conflicts['CREATE TABLE'])) {
+                $unknownCreateTable = $conflicts['CREATE TABLE'];
 
-                    $errorMessage .= " overwrite unknown table";
-                    if (\count($unknownCreateTable) > 1) {
-                        $errorMessage .= "s";
-                    }
-                    $errorMessage .= " '" . \implode("', '", $unknownCreateTable) . "'";
+                $errorMessage = "Can't overwrite unknown table";
+                if (\count($unknownCreateTable) > 1) {
+                    $errorMessage .= "s";
                 }
+                $errorMessage .= " '" . \implode("', '", $unknownCreateTable) . "'";
 
                 throw new SystemException($errorMessage);
             }
diff --git a/wcfsetup/install/files/lib/system/package/plugin/ScriptPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/ScriptPackageInstallationPlugin.class.php
index 3a8b47fd8a5..a0a1685f8df 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/ScriptPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/ScriptPackageInstallationPlugin.class.php
@@ -50,7 +50,7 @@ public function install()
     /**
      * Runs the script with the given path.
      */
-    private function run(string $scriptPath)
+    private function run(string $scriptPath): mixed
     {
         return include($scriptPath);
     }
diff --git a/wcfsetup/install/files/lib/system/package/plugin/SmileyPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/SmileyPackageInstallationPlugin.class.php
index 3c8253c21f9..7711592ef52 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/SmileyPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/SmileyPackageInstallationPlugin.class.php
@@ -120,6 +120,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -263,6 +264,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -303,6 +306,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -312,6 +316,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -324,6 +329,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/StylePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/StylePackageInstallationPlugin.class.php
index 1f8ef8192ee..40d510c6837 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/StylePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/StylePackageInstallationPlugin.class.php
@@ -18,6 +18,7 @@ class StylePackageInstallationPlugin extends AbstractPackageInstallationPlugin
 {
     /**
      * @inheritDoc
+     * @var string
      */
     public $className = StyleEditor::class;
 
diff --git a/wcfsetup/install/files/lib/system/package/plugin/TemplateListenerPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/TemplateListenerPackageInstallationPlugin.class.php
index 06d2577a486..9edafd19bcd 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/TemplateListenerPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/TemplateListenerPackageInstallationPlugin.class.php
@@ -140,6 +140,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -394,6 +395,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -428,6 +431,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -505,6 +509,7 @@ public function editEntry(IFormDocument $form, $identifier)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -519,6 +524,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -549,6 +555,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -568,6 +575,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/TemplatePackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/TemplatePackageInstallationPlugin.class.php
index 880b3da2afe..919cadbaee9 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/TemplatePackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/TemplatePackageInstallationPlugin.class.php
@@ -81,6 +81,7 @@ public function uninstall()
 
         \assert($this->installation instanceof PackageUninstallationDispatcher);
         foreach ($templates as $application => $templateNames) {
+            // @phpstan-ignore method.notFound
             $this->installation->deleteFiles(
                 Application::getDirectory($application),
                 $templateNames,
diff --git a/wcfsetup/install/files/lib/system/package/plugin/UserGroupOptionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/UserGroupOptionPackageInstallationPlugin.class.php
index 17bd0ff59f7..53af379872d 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/UserGroupOptionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/UserGroupOptionPackageInstallationPlugin.class.php
@@ -264,6 +264,7 @@ protected function getGroupIDs()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -317,6 +318,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -362,6 +365,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return UserGroupOptionHandler
      * @since   5.2
      */
     protected function getSortOptionHandler()
@@ -399,6 +403,7 @@ public function getCategoryOptions($categoryName = '', $inherit = true)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php
index 50b93224d42..35efb8a8941 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/UserMenuPackageInstallationPlugin.class.php
@@ -71,12 +71,13 @@ protected function getElement(\DOMXPath $xpath, array &$elements, \DOMElement $e
                 $solid === 'true' ? 'true' : 'false'
             );
         } else {
-            $elements[$element->tagName] = $element->nodeValue;
+            $elements[$element->tagName] = $element->textContent;
         }
     }
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -141,6 +142,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -173,6 +176,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/UserNotificationEventPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/UserNotificationEventPackageInstallationPlugin.class.php
index 706edc8a847..fc5a136ae72 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/UserNotificationEventPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/UserNotificationEventPackageInstallationPlugin.class.php
@@ -192,6 +192,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -310,6 +311,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -361,6 +364,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -373,6 +377,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -385,6 +390,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
@@ -410,6 +416,7 @@ protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form
 
     /**
      * @inheritDoc
+     * @return ?\DOMElement
      * @since   5.2
      */
     protected function prepareDeleteXmlElement(\DOMElement $element)
@@ -428,6 +435,7 @@ protected function prepareDeleteXmlElement(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function deleteObject(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/UserOptionPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/UserOptionPackageInstallationPlugin.class.php
index e850698c432..7113fd76efd 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/UserOptionPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/UserOptionPackageInstallationPlugin.class.php
@@ -80,8 +80,9 @@ class UserOptionPackageInstallationPlugin extends AbstractOptionPackageInstallat
 
     /**
      * @inheritDoc
+     * @param array<string, string|int|null> $category
      */
-    protected function saveCategory($category, $categoryXML = null)
+    protected function saveCategory($category)
     {
         // use for create and update
         $data = [
@@ -253,6 +254,7 @@ public function uninstall()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -397,6 +399,8 @@ static function (IFormDocument $document, array $parameters) {
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -445,6 +449,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return UserOptionHandler
      * @since   5.2
      */
     protected function getSortOptionHandler()
@@ -482,6 +487,7 @@ public function getCategoryOptions($categoryName = '', $inherit = true)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/plugin/UserProfileMenuPackageInstallationPlugin.class.php b/wcfsetup/install/files/lib/system/package/plugin/UserProfileMenuPackageInstallationPlugin.class.php
index 099d0a28d3f..07396e70e61 100644
--- a/wcfsetup/install/files/lib/system/package/plugin/UserProfileMenuPackageInstallationPlugin.class.php
+++ b/wcfsetup/install/files/lib/system/package/plugin/UserProfileMenuPackageInstallationPlugin.class.php
@@ -123,6 +123,7 @@ public static function getSyncDependencies()
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function addFormFields(IFormDocument $form)
@@ -198,6 +199,8 @@ protected function addFormFields(IFormDocument $form)
 
     /**
      * @inheritDoc
+     * @param bool $saveData
+     * @return array<string, int|string>
      * @since   5.2
      */
     protected function fetchElementData(\DOMElement $element, $saveData)
@@ -236,6 +239,7 @@ protected function fetchElementData(\DOMElement $element, $saveData)
 
     /**
      * @inheritDoc
+     * @return string
      * @since   5.2
      */
     public function getElementIdentifier(\DOMElement $element)
@@ -245,6 +249,7 @@ public function getElementIdentifier(\DOMElement $element)
 
     /**
      * @inheritDoc
+     * @return void
      * @since   5.2
      */
     protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
@@ -257,6 +262,7 @@ protected function setEntryListKeys(IDevtoolsPipEntryList $entryList)
 
     /**
      * @inheritDoc
+     * @return \DOMElement
      * @since   5.2
      */
     protected function prepareXmlElement(\DOMDocument $document, IFormDocument $form)
diff --git a/wcfsetup/install/files/lib/system/package/validation/PackageValidationArchive.class.php b/wcfsetup/install/files/lib/system/package/validation/PackageValidationArchive.class.php
index cc8b91bd9bf..b0366ba79cb 100644
--- a/wcfsetup/install/files/lib/system/package/validation/PackageValidationArchive.class.php
+++ b/wcfsetup/install/files/lib/system/package/validation/PackageValidationArchive.class.php
@@ -15,6 +15,7 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements \RecursiveIterator<int, self>
  */
 final class PackageValidationArchive implements \RecursiveIterator
 {
@@ -22,7 +23,7 @@ final class PackageValidationArchive implements \RecursiveIterator
      * list of excluded packages grouped by package
      * @var string[][][]
      */
-    private static $excludedPackages = [];
+    private static array $excludedPackages = [];
 
     /**
      * package archive object
@@ -33,7 +34,7 @@ final class PackageValidationArchive implements \RecursiveIterator
      * list of direct requirements delivered by this package
      * @var PackageValidationArchive[]
      */
-    private $children = [];
+    private array $children = [];
 
     /**
      * nesting depth
@@ -47,9 +48,8 @@ final class PackageValidationArchive implements \RecursiveIterator
 
     /**
      * associated package object
-     * @var Package
      */
-    private $package;
+    private ?Package $package = null;
 
     /**
      * children pointer
@@ -68,10 +68,8 @@ public function __construct(string $archive, int $depth = 0)
     /**
      * Validates this package and optionally it's delivered requirements. The set validation
      * mode will toggle between different checks.
-     *
-     * @param int $validationMode
      */
-    public function validate($validationMode, string $requiredVersion = ''): bool
+    public function validate(int $validationMode, string $requiredVersion = ''): bool
     {
         if ($validationMode !== PackageValidationManager::VALIDATION_EXCLUSION) {
             try {
@@ -201,10 +199,9 @@ private function validateApplication(): void
     /**
      * Validates if the package has suitable install or update instructions
      *
-     * @param int $validationMode
      * @throws  PackageValidationException
      */
-    private function validateInstructions(string $requiredVersion, $validationMode)
+    private function validateInstructions(string $requiredVersion, int $validationMode): void
     {
         $package = $this->getPackage();
 
@@ -258,11 +255,10 @@ private function validateInstructions(string $requiredVersion, $validationMode)
     /**
      * Validates install or update instructions against the corresponding PIP, unknown PIPs will be silently ignored.
      *
-     * @param string $type
      * @param mixed[][] $instructions
      * @throws  PackageValidationException
      */
-    private function validatePackageInstallationPlugins($type, array $instructions)
+    private function validatePackageInstallationPlugins(string $type, array $instructions): void
     {
         for ($i = 0, $length = \count($instructions); $i < $length; $i++) {
             $instruction = $instructions[$i];
@@ -290,7 +286,7 @@ private function validatePackageInstallationPlugins($type, array $instructions)
      *
      * @throws  PackageValidationException
      */
-    private function validateExclusion(string $package)
+    private function validateExclusion(string $package): void
     {
         $packageVersion = $this->archive->getPackageInfo('version');
 
diff --git a/wcfsetup/install/files/lib/system/package/validation/PackageValidationException.class.php b/wcfsetup/install/files/lib/system/package/validation/PackageValidationException.class.php
index aca7c1165c4..19c2ef24b0e 100644
--- a/wcfsetup/install/files/lib/system/package/validation/PackageValidationException.class.php
+++ b/wcfsetup/install/files/lib/system/package/validation/PackageValidationException.class.php
@@ -302,6 +302,8 @@ protected function getLegacyMessage($code)
 
     /**
      * @inheritDoc
+     *
+     * @return void
      */
     protected function logError()
     {
diff --git a/wcfsetup/install/files/lib/system/package/validation/PackageValidationManager.class.php b/wcfsetup/install/files/lib/system/package/validation/PackageValidationManager.class.php
index ecca2e09b6a..f4d9c9ab2c6 100644
--- a/wcfsetup/install/files/lib/system/package/validation/PackageValidationManager.class.php
+++ b/wcfsetup/install/files/lib/system/package/validation/PackageValidationManager.class.php
@@ -135,7 +135,7 @@ public function getVirtualPackage($package)
     /**
      * Returns the iterable package archive list.
      *
-     * @return  \RecursiveIteratorIterator
+     * @return  \RecursiveIteratorIterator<PackageValidationArchive>
      */
     public function getPackageValidationArchiveList()
     {
diff --git a/wcfsetup/install/files/lib/system/page/PageLocationManager.class.php b/wcfsetup/install/files/lib/system/page/PageLocationManager.class.php
index a3b3460842c..76d180024c9 100644
--- a/wcfsetup/install/files/lib/system/page/PageLocationManager.class.php
+++ b/wcfsetup/install/files/lib/system/page/PageLocationManager.class.php
@@ -16,6 +16,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ * @phpstan-type Location array{identifier: string, link: string, pageID: int, pageObjectID: int, title: string, useAsParentLocation: bool}
  */
 class PageLocationManager extends SingletonFactory
 {
@@ -27,13 +28,11 @@ class PageLocationManager extends SingletonFactory
 
     /**
      * list of locations with descending priority
-     * @var array
+     * @var list<Location>
      */
     protected $stack = [];
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function init()
     {
         $pageID = $pageObjectID = 0;
@@ -78,6 +77,7 @@ public function init()
      * @param int $pageObjectID page object id
      * @param ITitledLinkObject $locationObject optional label for breadcrumbs usage
      * @param bool $useAsParentLocation
+     * @return void
      * @throws  SystemException
      */
     public function addParentLocation(
@@ -124,7 +124,7 @@ public function addParentLocation(
     /**
      * Returns the list of locations with descending priority.
      *
-     * @return  array
+     * @return list<Location>
      */
     public function getLocations()
     {
@@ -139,6 +139,8 @@ public function getLocations()
 
     /**
      * Adds all parents as defined through the page configuration.
+     *
+     * @return void
      */
     protected function addParents()
     {
diff --git a/wcfsetup/install/files/lib/system/page/handler/CategoryArticleListPageHandler.class.php b/wcfsetup/install/files/lib/system/page/handler/CategoryArticleListPageHandler.class.php
index cfe22dc6e28..42718056c73 100644
--- a/wcfsetup/install/files/lib/system/page/handler/CategoryArticleListPageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/page/handler/CategoryArticleListPageHandler.class.php
@@ -18,6 +18,7 @@ class CategoryArticleListPageHandler extends AbstractLookupPageHandler implement
     use TDecoratedCategoryOnlineLocationLookupPageHandler;
 
     /**
+     * @return string
      * @see TDecoratedCategoryLookupPageHandler::getDecoratedCategoryClass()
      */
     protected function getDecoratedCategoryClass()
diff --git a/wcfsetup/install/files/lib/system/page/handler/IOnlineLocationPageHandler.class.php b/wcfsetup/install/files/lib/system/page/handler/IOnlineLocationPageHandler.class.php
index 35bcf88ae4f..6851cf7d4c8 100644
--- a/wcfsetup/install/files/lib/system/page/handler/IOnlineLocationPageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/page/handler/IOnlineLocationPageHandler.class.php
@@ -30,6 +30,7 @@ public function getOnlineLocation(Page $page, UserOnline $user);
      *
      * @param Page $page visited page
      * @param UserOnline $user user online object with request data
+     * @return void
      */
     public function prepareOnlineLocation(Page $page, UserOnline $user);
 }
diff --git a/wcfsetup/install/files/lib/system/page/handler/TOnlineLocationPageHandler.class.php b/wcfsetup/install/files/lib/system/page/handler/TOnlineLocationPageHandler.class.php
index 8021fcf4603..254c5eee941 100644
--- a/wcfsetup/install/files/lib/system/page/handler/TOnlineLocationPageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/page/handler/TOnlineLocationPageHandler.class.php
@@ -19,7 +19,7 @@
 trait TOnlineLocationPageHandler
 {
     /**
-     * @inheritDoc
+     * @return string
      */
     public function getOnlineLocation(Page $page, UserOnline $user)
     {
@@ -27,7 +27,7 @@ public function getOnlineLocation(Page $page, UserOnline $user)
     }
 
     /**
-     * @inheritDoc
+     * @return void
      */
     public function prepareOnlineLocation(Page $page, UserOnline $user)
     {
diff --git a/wcfsetup/install/files/lib/system/page/handler/TUserOnlineLocationPageHandler.class.php b/wcfsetup/install/files/lib/system/page/handler/TUserOnlineLocationPageHandler.class.php
index 37f61016340..b4d3b854b79 100644
--- a/wcfsetup/install/files/lib/system/page/handler/TUserOnlineLocationPageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/page/handler/TUserOnlineLocationPageHandler.class.php
@@ -50,6 +50,7 @@ public function getOnlineLocation(Page $page, UserOnline $user)
      *
      * @param Page $page visited page
      * @param UserOnline $user user online object with request data
+     * @return void
      * @see IOnlineLocationPageHandler::prepareOnlineLocation()
      */
     public function prepareOnlineLocation(Page $page, UserOnline $user)
diff --git a/wcfsetup/install/files/lib/system/page/handler/TrophyListPageHandler.class.php b/wcfsetup/install/files/lib/system/page/handler/TrophyListPageHandler.class.php
index b98590fc230..e2f726e61b0 100644
--- a/wcfsetup/install/files/lib/system/page/handler/TrophyListPageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/page/handler/TrophyListPageHandler.class.php
@@ -18,6 +18,7 @@ class TrophyListPageHandler extends AbstractLookupPageHandler
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected function getDecoratedCategoryClass()
     {
diff --git a/wcfsetup/install/files/lib/system/payment/type/IPaymentType.class.php b/wcfsetup/install/files/lib/system/payment/type/IPaymentType.class.php
index 6e89d3c430e..d9885189ba6 100644
--- a/wcfsetup/install/files/lib/system/payment/type/IPaymentType.class.php
+++ b/wcfsetup/install/files/lib/system/payment/type/IPaymentType.class.php
@@ -20,7 +20,8 @@ interface IPaymentType
      * @param string $currency
      * @param string $transactionID
      * @param string $status
-     * @param array $transactionDetails
+     * @param mixed[] $transactionDetails
+     * @return void
      */
     public function processTransaction(
         $paymentMethodObjectTypeID,
diff --git a/wcfsetup/install/files/lib/system/poll/IPollHandler.class.php b/wcfsetup/install/files/lib/system/poll/IPollHandler.class.php
index e5b052f0bdc..881f54aa212 100644
--- a/wcfsetup/install/files/lib/system/poll/IPollHandler.class.php
+++ b/wcfsetup/install/files/lib/system/poll/IPollHandler.class.php
@@ -31,6 +31,7 @@ public function canVote();
      * Returns related object for given poll object.
      *
      * @param Poll $poll
+     * @return ?object
      */
     public function getRelatedObject(Poll $poll);
 }
diff --git a/wcfsetup/install/files/lib/system/poll/PollManager.class.php b/wcfsetup/install/files/lib/system/poll/PollManager.class.php
index 1ceea12be30..8525fac1434 100644
--- a/wcfsetup/install/files/lib/system/poll/PollManager.class.php
+++ b/wcfsetup/install/files/lib/system/poll/PollManager.class.php
@@ -92,6 +92,7 @@ protected function init()
      * Removes a list of polls by id.
      *
      * @param int[] $pollIDs
+     * @return void
      */
     public function removePolls(array $pollIDs)
     {
@@ -162,7 +163,8 @@ public function setObject($objectType, $objectID, $pollID = 0)
     /**
      * Reads form parameters for polls.
      *
-     * @param array $postData optional post data to be used instead of $_POST
+     * @param array<string, mixed> $postData optional post data to be used instead of $_POST
+     * @return void
      */
     public function readFormParameters(array $postData = [])
     {
@@ -212,6 +214,8 @@ public function readFormParameters(array $postData = [])
 
     /**
      * Validates poll parameters.
+     *
+     * @return void
      */
     public function validate()
     {
@@ -315,7 +319,7 @@ public function save($objectID = null)
      * This method either creates a new poll or updates or deletes an existing poll.
      *
      * @param IPollContainer $pollContainer object the poll belongs to
-     * @param array $pollData poll data
+     * @param mixed[] $pollData poll data
      * @return  null|int                    id of the poll
      * @since   5.2
      */
@@ -350,6 +354,8 @@ public function savePoll(IPollContainer $pollContainer, array $pollData)
 
     /**
      * Assigns variables for poll management or display.
+     *
+     * @return void
      */
     public function assignVariables()
     {
diff --git a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
index acd5bc0a17b..93fbec6f283 100644
--- a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\reaction;
 
+use wcf\data\DatabaseObject;
 use wcf\data\like\ILikeObjectTypeProvider;
 use wcf\data\like\Like;
 use wcf\data\like\LikeList;
@@ -153,6 +154,7 @@ public function getDataAttributes($objectTypeName, $objectID)
      *
      * @param string $objectTypeName
      * @param int[] $objectIDs
+     * @return void
      */
     public function cacheLikeableObjects($objectTypeName, array $objectIDs)
     {
@@ -163,7 +165,7 @@ public function cacheLikeableObjects($objectTypeName, array $objectIDs)
             );
         }
 
-        /** @var ILikeObjectTypeProvider $objectTypeProcessor */
+        /** @var ILikeObjectTypeProvider<DatabaseObject> $objectTypeProcessor */
         $objectTypeProcessor = $objectType->getProcessor();
 
         $objects = $objectTypeProcessor->getObjectsByIDs($objectIDs);
@@ -256,7 +258,7 @@ public function getLikeObjects(ObjectType $objectType)
      * like objects
      *
      * @param ObjectType $objectType
-     * @param array $objectIDs
+     * @param int[] $objectIDs
      * @return  int
      */
     public function loadLikeObjects(ObjectType $objectType, array $objectIDs)
@@ -309,8 +311,13 @@ public function loadLikeObjects(ObjectType $objectType, array $objectIDs)
      * @param User $user
      * @param int $reactionTypeID
      * @param int $time
-     * @return  array
-     * @throws  DatabaseQueryException
+     * @return array{
+     *  cachedReactions: array<int, int>,
+     *  reactionTypeID: ?int,
+     *  like?: Like,
+     *  likeObject: LikeObject|array{},
+     *  cumulativeLikes: int,
+     * }
      */
     public function react(ILikeObject $likeable, User $user, $reactionTypeID, $time = TIME_NOW)
     {
@@ -451,7 +458,7 @@ public function react(ILikeObject $likeable, User $user, $reactionTypeID, $time
      * @param LikeObject $likeObject
      * @param Like $like
      * @param ReactionType $reactionType
-     * @return  array
+     * @return array{cumulativeLikes: int, cachedReactions: array<int, int>, likeObject: LikeObject}
      */
     private function updateLikeObject(
         ILikeObject $likeable,
@@ -548,6 +555,7 @@ private function updateLikeObject(
      * @param LikeObject $likeObject
      * @param Like $like
      * @param ReactionType $reactionType
+     * @return void
      */
     private function updateUsersLikeCounter(
         ILikeObject $likeable,
@@ -579,7 +587,12 @@ private function updateUsersLikeCounter(
      * @param ILikeObject $likeable
      * @param LikeObject $likeObject
      * @param User $user
-     * @return  array
+     * @return array{
+     *  cachedReactions: array<int, int>,
+     *  reactionTypeID: null,
+     *  likeObject: LikeObject|array{},
+     *  cumulativeLikes: ?int,
+     * }
      */
     public function revertReact(Like $like, ILikeObject $likeable, LikeObject $likeObject, User $user)
     {
@@ -641,7 +654,7 @@ public function revertReact(Like $like, ILikeObject $likeable, LikeObject $likeO
      *
      * @param LikeObject $likeObject
      * @param Like $like
-     * @return  array
+     * @return array{cumulativeLikes: int, cachedReactions: array<int, int>, likeObject: LikeObject}
      */
     private function revertLikeObject(LikeObject $likeObject, Like $like)
     {
@@ -692,6 +705,7 @@ private function revertLikeObject(LikeObject $likeObject, Like $like)
      * @param string $objectType
      * @param int[] $objectIDs
      * @param string[] $notificationObjectTypes
+     * @return void
      */
     public function removeReactions($objectType, array $objectIDs, array $notificationObjectTypes = [])
     {
@@ -783,7 +797,13 @@ public function removeReactions($objectType, array $objectIDs, array $notificati
      *
      * @param LikeObject $likeObject
      * @param User $user
-     * @return  array
+     * @return array{
+     *  likes: int,
+     *  dislikes: int,
+     *  cumulativeLikes: int,
+     *  reactionTypeID: int,
+     *  likeValue: int
+     * }
      */
     protected function loadLikeStatus(LikeObject $likeObject, User $user)
     {
@@ -840,8 +860,8 @@ public function getFirstReactionTypeID()
     /**
      * Removes deleted reactions from the reaction counter for the like object table.
      *
-     * @param array $cachedReactions
-     * @return      array
+     * @param array<int, int> $cachedReactions
+     * @return array<int, int>
      */
     private function cleanUpCachedReactions(array $cachedReactions)
     {
@@ -856,7 +876,7 @@ private function cleanUpCachedReactions(array $cachedReactions)
 
     /**
      * @param string|null $cachedReactions
-     * @return array|null
+     * @return array{count: int, other: int, reaction: ?ReactionType}|null
      * @since 5.2
      */
     public function getTopReaction($cachedReactions)
diff --git a/wcfsetup/install/files/lib/system/request/ControllerMap.class.php b/wcfsetup/install/files/lib/system/request/ControllerMap.class.php
index 0eb9c9a2c05..51f0a7891f1 100644
--- a/wcfsetup/install/files/lib/system/request/ControllerMap.class.php
+++ b/wcfsetup/install/files/lib/system/request/ControllerMap.class.php
@@ -21,35 +21,39 @@
 final class ControllerMap extends SingletonFactory
 {
     /**
-     * @var array
+     * @var array{
+     *  lookup: array<string, array<string, string>>,
+     *  reverse: array<string, array<string, string>>,
+     * }
      * @since   5.2
      */
-    protected $applicationOverrides;
+    private array $applicationOverrides;
 
     /**
-     * @var array
+     * @var array<string, array<string, array<string, string>>>
      */
-    protected $ciControllers;
+    private array $ciControllers;
 
     /**
-     * @var array
+     * @var array{
+     *  lookup: array<string, array<string, string>>,
+     *  reverse: array<string, array<string, string>>,
+     * }
      */
-    protected $customUrls;
+    private array $customUrls;
 
     /**
-     * @var string[][]
+     * @var array<string, array<string, string>>
      */
-    protected $landingPages;
+    private array $landingPages;
 
     /**
      * list of <ControllerName> to <controller-name> mappings
      * @var array<string, string>
      */
-    protected $lookupCache = [];
+    private array $lookupCache = [];
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     protected function init()
     {
         $this->applicationOverrides = RoutingCacheBuilder::getInstance()->getData([], 'applicationOverrides');
@@ -130,7 +134,7 @@ public function resolve(string $application, string $controller, bool $isAcpRequ
      *
      * URL -> Controller
      *
-     * @return  array       empty array if there is no exact match
+     * @return array{}|array{className: string, controller: string}|array{className: string, controller: string, cmsPageID: string, cmsPageLanguageID: string}
      */
     public function resolveCustomController(string $application, string $controller): array
     {
@@ -287,7 +291,7 @@ public function isDefaultController(string $application, string $controller): bo
     /**
      * Returns true if currently active request represents the global landing page.
      *
-     * @param array $metaData
+     * @param array<string, mixed> $metaData
      */
     public function isLandingPage(string $className, array $metaData): bool
     {
@@ -324,7 +328,7 @@ public function getApplicationOverride(string $application, string $controller):
      *
      * @return      string[]|null   className and controller, or null if this is not a legacy controller name
      */
-    protected function getLegacyClassData(string $application, string $controller, bool $isAcpRequest)
+    private function getLegacyClassData(string $application, string $controller, bool $isAcpRequest)
     {
         $environment = $isAcpRequest ? 'acp' : 'frontend';
         if (isset($this->ciControllers[$application][$environment][$controller])) {
@@ -348,7 +352,7 @@ protected function getLegacyClassData(string $application, string $controller, b
      * @param $pageType page type, e.g. 'form' or 'action'
      * @return  string[]|null   className and controller
      */
-    protected function getClassData(string $application, string $controller, bool $isAcpRequest, string $pageType)
+    private function getClassData(string $application, string $controller, bool $isAcpRequest, string $pageType)
     {
         $className = $application . '\\' . ($isAcpRequest ? 'acp\\' : '') . $pageType . '\\' . $controller . \ucfirst($pageType);
         if (!\class_exists($className)) {
diff --git a/wcfsetup/install/files/lib/system/request/LinkHandler.class.php b/wcfsetup/install/files/lib/system/request/LinkHandler.class.php
index c2fd3bfd4f9..7430d701ff1 100644
--- a/wcfsetup/install/files/lib/system/request/LinkHandler.class.php
+++ b/wcfsetup/install/files/lib/system/request/LinkHandler.class.php
@@ -72,6 +72,7 @@ protected function init()
      * Important: The controller class is not checked if it actually exists.
      * That check happens during the runtime.
      *
+     * @param array<string, mixed> $parameters
      * @throws  \InvalidArgumentException   if the passed string is no controller class name
      * @since   5.2
      */
@@ -93,6 +94,8 @@ public function getControllerLink(string $controllerClass, array $parameters = [
 
     /**
      * Returns a relative link.
+     *
+     * @param array<string, mixed> $parameters
      */
     public function getLink(?string $controller = null, array $parameters = [], string $url = ''): string
     {
diff --git a/wcfsetup/install/files/lib/system/request/Request.class.php b/wcfsetup/install/files/lib/system/request/Request.class.php
index d62dbc979b0..e3108578e65 100644
--- a/wcfsetup/install/files/lib/system/request/Request.class.php
+++ b/wcfsetup/install/files/lib/system/request/Request.class.php
@@ -5,7 +5,9 @@
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\RequestHandlerInterface;
+use wcf\action\IAction;
 use wcf\http\LegacyPlaceholderResponse;
+use wcf\page\IPage;
 
 /**
  * Represents a page request.
@@ -20,14 +22,16 @@ final class Request implements RequestHandlerInterface
 
     private readonly bool $isLandingPage;
 
+    /**
+     * @var array{cms?: array{pageID: int, languageID: int}}
+     */
     private readonly array $metaData;
 
+    private RequestHandlerInterface|IAction|IPage $requestObject;
+
     /**
-     * request object
-     * @var object
+     * @param array{cms?: array{pageID: int, languageID: int}} $metaData
      */
-    private $requestObject;
-
     public function __construct(string $className, array $metaData, bool $isLandingPage)
     {
         $this->className = $className;
@@ -40,7 +44,7 @@ public function __construct(string $className, array $metaData, bool $isLandingP
      */
     public function handle(ServerRequestInterface $request): ResponseInterface
     {
-        if ($this->requestObject === null) {
+        if (!isset($this->requestObject)) {
             $this->requestObject = new $this->className();
         }
 
@@ -76,21 +80,23 @@ public function getClassName(): string
     /**
      * Returns request meta data.
      *
-     * @return  array
-     * @since   3.0
+     * @return array{cms?: array{pageID: int, languageID: int}}
+     * @since 3.0
      */
-    public function getMetaData()
+    public function getMetaData(): array
     {
         return $this->metaData;
     }
 
     /**
      * Returns the current request object.
-     *
-     * @return  object
      */
-    public function getRequestObject()
+    public function getRequestObject(): RequestHandlerInterface|IAction|IPage|null
     {
+        if (!isset($this->requestObject)) {
+            return null;
+        }
+
         return $this->requestObject;
     }
 
@@ -117,10 +123,10 @@ public function isAvailableDuringOfflineMode(): bool
     /**
      * Returns the current page id.
      *
-     * @return  int     current page id or `0` if unknown
+     * @return int current page id or `0` if unknown
      * @deprecated 6.1 use `RequestHandler::getInstance()->getActivePageID()` instead
      */
-    public function getPageID()
+    public function getPageID(): int
     {
         return RequestHandler::getInstance()->getActivePageID() ?: 0;
     }
diff --git a/wcfsetup/install/files/lib/system/request/RouteHandler.class.php b/wcfsetup/install/files/lib/system/request/RouteHandler.class.php
index adb6c970f35..26daced5e1b 100644
--- a/wcfsetup/install/files/lib/system/request/RouteHandler.class.php
+++ b/wcfsetup/install/files/lib/system/request/RouteHandler.class.php
@@ -24,33 +24,28 @@ final class RouteHandler extends SingletonFactory
 {
     /**
      * current host and protocol
-     * @var string
      */
-    private static $host = '';
+    private static string $host = '';
 
     /**
      * current absolute path
-     * @var string
      */
-    private static $path = '';
+    private static string $path = '';
 
     /**
      * current path info component
-     * @var string
      */
-    private static $pathInfo;
+    private static string $pathInfo;
 
     /**
      * HTTP protocol, either 'http://' or 'https://'
-     * @var string
      */
-    private static $protocol = '';
+    private static string $protocol = '';
 
     /**
      * HTTP encryption
-     * @var bool
      */
-    private static $secure;
+    private static bool $secure;
 
     /**
      * true if the default controller is used (support for custom landing page)
@@ -70,9 +65,9 @@ final class RouteHandler extends SingletonFactory
 
     /**
      * parsed route data
-     * @var array
+     * @var array<string, mixed>
      */
-    private $routeData;
+    private array $routeData;
 
     /**
      * Sets default routes.
@@ -98,7 +93,7 @@ protected function init()
      *
      * @param IRequestRoute $route
      */
-    public function addRoute(IRequestRoute $route)
+    public function addRoute(IRequestRoute $route): void
     {
         \array_unshift($this->routes, $route);
     }
@@ -106,9 +101,9 @@ public function addRoute(IRequestRoute $route)
     /**
      * Returns all registered routes.
      *
-     * @return  IRequestRoute[]
+     * @return IRequestRoute[]
      **/
-    public function getRoutes()
+    public function getRoutes(): array
     {
         return $this->routes;
     }
@@ -175,9 +170,9 @@ public function isRenamedController(): bool
     /**
      * Returns parsed route data
      *
-     * @return  array
+     * @return array<string, mixed>
      */
-    public function getRouteData()
+    public function getRouteData(): array
     {
         return $this->routeData;
     }
@@ -197,13 +192,10 @@ private function registerRouteData(): void
      * Builds a route based upon route components, this is nothing
      * but a reverse lookup.
      *
-     * @param string $application application identifier
-     * @param array $components
-     * @param bool $isACP
-     * @return  string
+     * @param array<string, mixed> $components
      * @throws  SystemException
      */
-    public function buildRoute($application, array $components, $isACP = null)
+    public function buildRoute(string $application, array $components, ?bool $isACP = null): string
     {
         if ($isACP === null) {
             $isACP = RequestHandler::getInstance()->isACPRequest();
@@ -248,7 +240,7 @@ public static function isValidCustomUrl($customUrl): bool
      */
     public static function secureConnection(): bool
     {
-        if (self::$secure === null) {
+        if (!isset(self::$secure)) {
             self::$secure = false;
 
             if (
@@ -317,6 +309,8 @@ public static function getHost(): string
 
     /**
      * Returns absolute domain path.
+     *
+     * @param string[] $removeComponents
      */
     public static function getPath(array $removeComponents = []): string
     {
@@ -349,7 +343,7 @@ public static function getPath(array $removeComponents = []): string
      */
     public static function getPathInfo(): string
     {
-        if (self::$pathInfo === null) {
+        if (!isset(self::$pathInfo)) {
             self::$pathInfo = '';
 
             if (!empty($_SERVER['QUERY_STRING'])) {
diff --git a/wcfsetup/install/files/lib/system/request/route/DynamicRequestRoute.class.php b/wcfsetup/install/files/lib/system/request/route/DynamicRequestRoute.class.php
index e6777de47f8..d3050472bdc 100644
--- a/wcfsetup/install/files/lib/system/request/route/DynamicRequestRoute.class.php
+++ b/wcfsetup/install/files/lib/system/request/route/DynamicRequestRoute.class.php
@@ -45,9 +45,6 @@ class DynamicRequestRoute implements IRequestRoute
      */
     protected $routeData = [];
 
-    /**
-     * DynamicRequestRoute constructor.
-     */
     public function __construct()
     {
         $this->init();
@@ -55,6 +52,8 @@ public function __construct()
 
     /**
      * Sets default routing information.
+     *
+     * @return void
      */
     protected function init()
     {
@@ -81,7 +80,8 @@ protected function init()
     }
 
     /**
-     * @inheritDoc
+     * @param bool $isACP
+     * @return void
      */
     public function setIsACP($isACP)
     {
@@ -92,6 +92,7 @@ public function setIsACP($isACP)
      * Sets the build schema used to build outgoing links.
      *
      * @param string $buildSchema
+     * @return void
      */
     public function setBuildSchema($buildSchema)
     {
@@ -124,6 +125,7 @@ public function setBuildSchema($buildSchema)
      * Sets the route pattern used to evaluate an incoming request.
      *
      * @param string $pattern
+     * @return void
      */
     public function setPattern($pattern)
     {
@@ -134,6 +136,7 @@ public function setPattern($pattern)
      * Sets the list of required components.
      *
      * @param string[] $requiredComponents
+     * @return void
      */
     public function setRequiredComponents(array $requiredComponents)
     {
diff --git a/wcfsetup/install/files/lib/system/request/route/IRequestRoute.class.php b/wcfsetup/install/files/lib/system/request/route/IRequestRoute.class.php
index 9d51a6a3513..deebe94a02e 100644
--- a/wcfsetup/install/files/lib/system/request/route/IRequestRoute.class.php
+++ b/wcfsetup/install/files/lib/system/request/route/IRequestRoute.class.php
@@ -15,15 +15,15 @@ interface IRequestRoute
     /**
      * Builds a link upon route components.
      *
-     * @param array $components
-     * @return  string
+     * @param array<string, string> $components
+     * @return string
      */
     public function buildLink(array $components);
 
     /**
      * Returns true if current route can handle the build request.
      *
-     * @param array $components
+     * @param array<string, string> $components
      * @return  bool
      */
     public function canHandle(array $components);
@@ -31,7 +31,7 @@ public function canHandle(array $components);
     /**
      * Returns parsed route data.
      *
-     * @return  array
+     * @return array<string, string|bool>
      */
     public function getRouteData();
 
diff --git a/wcfsetup/install/files/lib/system/request/route/LookupRequestRoute.class.php b/wcfsetup/install/files/lib/system/request/route/LookupRequestRoute.class.php
index afc253bc5c6..70fa7d2a43c 100644
--- a/wcfsetup/install/files/lib/system/request/route/LookupRequestRoute.class.php
+++ b/wcfsetup/install/files/lib/system/request/route/LookupRequestRoute.class.php
@@ -19,9 +19,9 @@ final class LookupRequestRoute implements IRequestRoute
 {
     /**
      * list of parsed route information
-     * @var array
+     * @var array{id?: string, title?: string, controller?: string, isDefaultController?: boolean}
      */
-    protected array $routeData = [];
+    private array $routeData = [];
 
     /**
      * @inheritDoc
diff --git a/wcfsetup/install/files/lib/system/request/route/StaticRequestRoute.class.php b/wcfsetup/install/files/lib/system/request/route/StaticRequestRoute.class.php
index 324910eb040..3957de846a8 100644
--- a/wcfsetup/install/files/lib/system/request/route/StaticRequestRoute.class.php
+++ b/wcfsetup/install/files/lib/system/request/route/StaticRequestRoute.class.php
@@ -34,6 +34,9 @@ class StaticRequestRoute extends DynamicRequestRoute
 
     /**
      * Always throws. This method only exists because StaticRequestRoute inherits from DynamicRequestRoute.
+     *
+     * @param boolean $isACP
+     * @return void
      */
     public function setIsACP($isACP)
     {
@@ -53,6 +56,7 @@ public function isACP()
      * for controllers requiring a custom set of additional parameters.
      *
      * @param bool $matchController
+     * @return void
      */
     public function setMatchController($matchController)
     {
@@ -64,6 +68,7 @@ public function setMatchController($matchController)
      *
      * @param string $application
      * @param string $controller
+     * @return void
      */
     public function setStaticController($application, $controller)
     {
diff --git a/wcfsetup/install/files/lib/system/search/AbstractSearchIndexManager.class.php b/wcfsetup/install/files/lib/system/search/AbstractSearchIndexManager.class.php
index 71adb13ea39..29913b3a974 100644
--- a/wcfsetup/install/files/lib/system/search/AbstractSearchIndexManager.class.php
+++ b/wcfsetup/install/files/lib/system/search/AbstractSearchIndexManager.class.php
@@ -41,6 +41,8 @@ public function createSearchIndices()
 
     /**
      * Creates the search index for given object type.
+     *
+     * @return bool
      */
     abstract protected function createSearchIndex(ObjectType $objectType);
 
diff --git a/wcfsetup/install/files/lib/system/search/ArticleSearch.class.php b/wcfsetup/install/files/lib/system/search/ArticleSearch.class.php
index 1d85da01883..7cebe4ee3c2 100644
--- a/wcfsetup/install/files/lib/system/search/ArticleSearch.class.php
+++ b/wcfsetup/install/files/lib/system/search/ArticleSearch.class.php
@@ -122,6 +122,9 @@ public function getConditionBuilder(array $parameters): ?PreparedStatementCondit
         return $conditionBuilder;
     }
 
+    /**
+     * @return list<int>
+     */
     private function getArticleCategoryIDs(int $categoryID): array
     {
         $categoryIDs = [];
diff --git a/wcfsetup/install/files/lib/system/search/IContextAwareSearchEngine.class.php b/wcfsetup/install/files/lib/system/search/IContextAwareSearchEngine.class.php
index 4c21b0fceff..6b371cc8e91 100644
--- a/wcfsetup/install/files/lib/system/search/IContextAwareSearchEngine.class.php
+++ b/wcfsetup/install/files/lib/system/search/IContextAwareSearchEngine.class.php
@@ -29,6 +29,7 @@ public function getConditionBuilderClassName();
      * Returns the inner join query and the condition parameters. This method is allowed to return NULL for both the
      * 'fulltextCondition' and 'searchIndexCondition' index instead of a PreparedStatementConditionBuilder instance.
      *
+     * @param array{parentID?: int, containerID?: int} $contextFilter
      * @return  array{
      *              fulltextCondition: ?PreparedStatementConditionBuilder,
      *              searchIndexCondition: ?PreparedStatementConditionBuilder,
@@ -47,6 +48,11 @@ public function getInnerJoinWithContext(
 
     /**
      * Searches for the given string and returns the data of the found messages.
+     *
+     * @param list<string> $objectTypes
+     * @param array<string, array{parentID?: int, containerID?: int}> $contextFilter
+     * @param array<string, PreparedStatementConditionBuilder> $additionalConditions
+     * @return list<array{objectID: int, objectType: string}>
      */
     public function searchWithContext(
         string $q,
diff --git a/wcfsetup/install/files/lib/system/search/IContextAwareSearchProvider.class.php b/wcfsetup/install/files/lib/system/search/IContextAwareSearchProvider.class.php
index 3c94596fde9..2ab48f32ac3 100644
--- a/wcfsetup/install/files/lib/system/search/IContextAwareSearchProvider.class.php
+++ b/wcfsetup/install/files/lib/system/search/IContextAwareSearchProvider.class.php
@@ -19,6 +19,9 @@ interface IContextAwareSearchProvider extends ISearchProvider
     /**
      * Returns the context filter that is being applied
      * to the inner search query.
+     *
+     * @param array<string, mixed> $parameters
+     * @return array<string, mixed>
      */
     public function getContextFilter(array $parameters): array;
 }
diff --git a/wcfsetup/install/files/lib/system/search/ISearchEngine.class.php b/wcfsetup/install/files/lib/system/search/ISearchEngine.class.php
index 72032884a9a..e5a75a2956e 100644
--- a/wcfsetup/install/files/lib/system/search/ISearchEngine.class.php
+++ b/wcfsetup/install/files/lib/system/search/ISearchEngine.class.php
@@ -49,6 +49,7 @@ public function getInnerJoin(
      * Removes engine-specific special characters from a string.
      *
      * @param string $string
+     * @return string
      */
     public function removeSpecialCharacters($string);
 
@@ -56,13 +57,13 @@ public function removeSpecialCharacters($string);
      * Searches for the given string and returns the data of the found messages.
      *
      * @param string $q
-     * @param array $objectTypes
+     * @param string[] $objectTypes
      * @param bool $subjectOnly
      * @param PreparedStatementConditionBuilder $searchIndexCondition
-     * @param array $additionalConditions
+     * @param array<string, PreparedStatementConditionBuilder> $additionalConditions
      * @param string $orderBy
      * @param int $limit
-     * @return  array
+     * @return list<array{objectID: int, objectType: string}>
      */
     public function search(
         $q,
diff --git a/wcfsetup/install/files/lib/system/search/ISearchIndexManager.class.php b/wcfsetup/install/files/lib/system/search/ISearchIndexManager.class.php
index cdfc5e7705c..c509b55e1d5 100644
--- a/wcfsetup/install/files/lib/system/search/ISearchIndexManager.class.php
+++ b/wcfsetup/install/files/lib/system/search/ISearchIndexManager.class.php
@@ -23,6 +23,7 @@ interface ISearchIndexManager
      * @param string $username
      * @param int $languageID
      * @param string $metaData
+     * @return void
      */
     public function set(
         $objectType,
@@ -41,6 +42,7 @@ public function set(
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public function delete($objectType, array $objectIDs);
 
@@ -48,21 +50,28 @@ public function delete($objectType, array $objectIDs);
      * Resets the search index.
      *
      * @param string $objectType
+     * @return void
      */
     public function reset($objectType);
 
     /**
      * Creates the search index for all searchable objects.
+     *
+     * @return void
      */
     public function createSearchIndices();
 
     /**
      * Begins the bulk operation.
+     *
+     * @return void
      */
     public function beginBulkOperation();
 
     /**
      * Commits the bulk operation.
+     *
+     * @return void
      */
     public function commitBulkOperation();
 }
diff --git a/wcfsetup/install/files/lib/system/search/ISearchProvider.class.php b/wcfsetup/install/files/lib/system/search/ISearchProvider.class.php
index 1a1c3f8fec2..e13ff972215 100644
--- a/wcfsetup/install/files/lib/system/search/ISearchProvider.class.php
+++ b/wcfsetup/install/files/lib/system/search/ISearchProvider.class.php
@@ -17,6 +17,9 @@ interface ISearchProvider
 {
     /**
      * Caches the data for the given object ids.
+     *
+     * @param int[] $objectIDs
+     * @param mixed[] $additionalData
      */
     public function cacheObjects(array $objectIDs, ?array $additionalData = null): void;
 
@@ -38,6 +41,8 @@ public function getApplication(): string;
     /**
      * Returns the search conditions of this provider or `null` if no special search conditions are necessary.
      * If this provider is the only provider that is searched, the search parameters are passed.
+     *
+     * @param array<string, mixed> $parameters
      */
     public function getConditionBuilder(array $parameters): ?PreparedStatementConditionBuilder;
 
@@ -73,6 +78,8 @@ public function getTimeFieldName(): string;
 
     /**
      * Returns additional search information.
+     *
+     * @return mixed[]
      */
     public function getAdditionalData(): ?array;
 
diff --git a/wcfsetup/install/files/lib/system/search/ISearchableObjectType.class.php b/wcfsetup/install/files/lib/system/search/ISearchableObjectType.class.php
index 3e0d3a433a4..9c4602b01df 100644
--- a/wcfsetup/install/files/lib/system/search/ISearchableObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/search/ISearchableObjectType.class.php
@@ -19,8 +19,9 @@ interface ISearchableObjectType
     /**
      * Caches the data for the given object ids.
      *
-     * @param array $objectIDs
-     * @param array $additionalData
+     * @param int[] $objectIDs
+     * @param mixed[]|null $additionalData
+     * @return void
      */
     public function cacheObjects(array $objectIDs, ?array $additionalData = null);
 
@@ -36,6 +37,7 @@ public function getObject($objectID);
      * Shows the form part of this object type.
      *
      * @param IForm $form instance of the form class where the search has taken place
+     * @return void
      */
     public function show(?IForm $form = null);
 
@@ -135,6 +137,7 @@ public function getOuterSQLQuery(
     /**
      * Sets the location in menu/breadcrumbs.
      *
+     * @return void
      * @since   3.0
      */
     public function setLocation();
diff --git a/wcfsetup/install/files/lib/system/search/SearchHandler.class.php b/wcfsetup/install/files/lib/system/search/SearchHandler.class.php
index 31557569bfe..a9772d50c9c 100644
--- a/wcfsetup/install/files/lib/system/search/SearchHandler.class.php
+++ b/wcfsetup/install/files/lib/system/search/SearchHandler.class.php
@@ -63,12 +63,15 @@ final class SearchHandler
      */
     private $results = [];
 
+    /**
+     * @param mixed[] $parameters
+     */
     public function __construct(array $parameters)
     {
         $this->parameters = $parameters;
     }
 
-    public function search()
+    public function search(): ?Search
     {
         $this->initParameters();
         $this->buildConditions();
@@ -266,6 +269,9 @@ private function getSearchFormEmulation(): SearchForm
         return $form;
     }
 
+    /**
+     * @return int[]
+     */
     private function getUserIDs(): array
     {
         if ($this->userIDs === null) {
@@ -383,6 +389,9 @@ private function saveSearch(): Search
         return $resultValues['returnValues'];
     }
 
+    /**
+     * @return mixed[]
+     */
     private function getAdditionalData(): array
     {
         $additionalData = [];
diff --git a/wcfsetup/install/files/lib/system/search/SearchIndexManager.class.php b/wcfsetup/install/files/lib/system/search/SearchIndexManager.class.php
index 08f9d0bb04c..ad97c79cd4d 100644
--- a/wcfsetup/install/files/lib/system/search/SearchIndexManager.class.php
+++ b/wcfsetup/install/files/lib/system/search/SearchIndexManager.class.php
@@ -21,7 +21,7 @@ class SearchIndexManager extends SingletonFactory implements IContextAwareSearch
 {
     /**
      * list of available object types
-     * @var array
+     * @var array<string, ObjectType>
      */
     protected $availableObjectTypes = [];
 
diff --git a/wcfsetup/install/files/lib/system/search/SearchResultHandler.class.php b/wcfsetup/install/files/lib/system/search/SearchResultHandler.class.php
index 0a44cb797d4..5a281b516b2 100644
--- a/wcfsetup/install/files/lib/system/search/SearchResultHandler.class.php
+++ b/wcfsetup/install/files/lib/system/search/SearchResultHandler.class.php
@@ -6,6 +6,7 @@
 use wcf\data\search\Search;
 use wcf\page\SearchResultPage;
 use wcf\system\exception\ImplementationException;
+use wcf\system\exception\SystemException;
 
 /**
  * Provides the results of a full-text search.
@@ -17,35 +18,28 @@
  */
 final class SearchResultHandler
 {
-    /**
-     * @var Search
-     */
-    private $search;
+    private readonly Search $search;
 
     /**
-     * @var array
+     * @var array{
+     *  query: string,
+     *  objectTypeNames: string[],
+     *  results: list<array{objectID: int, objectType: string}>,
+     *  additionalData: array<string, mixed>
+     * }
      */
-    private $searchData;
+    private array $searchData;
 
     /**
-     * @var array
+     * @var list<ISearchResultObject>
      */
-    private $messages = [];
+    private array $messages = [];
 
-    /**
-     * @var int
-     */
-    private $startIndex = 0;
+    private int $startIndex = 0;
 
-    /**
-     * @var int
-     */
-    private $limit = 0;
+    private int $limit = 0;
 
-    /**
-     * @var int
-     */
-    private $endIndex = 0;
+    private int $endIndex = 0;
 
     public function __construct(Search $search, int $startIndex = 0, int $limit = SEARCH_RESULTS_PER_PAGE)
     {
@@ -74,6 +68,9 @@ public function loadSearchResults(): void
         $this->readMessages();
     }
 
+    /**
+     * @return list<ISearchResultObject>
+     */
     public function getSearchResults(): array
     {
         return $this->messages;
@@ -123,6 +120,9 @@ public function getQuery(): string
         return $this->searchData['query'];
     }
 
+    /**
+     * @return array{templateName: string, application: string}
+     */
     public function getTemplateName(): array
     {
         if (\count($this->searchData['objectTypeNames']) === 1) {
@@ -157,6 +157,8 @@ public function getCustomIcons(): array
 
     /**
      * Will be removed with 6.0 once all search providers have switched to ISearchProvider.
+     *
+     * @return array{templateName: string, application: string}
      * @deprecated 5.5
      */
     private function getLegacyTemplateName(): array
diff --git a/wcfsetup/install/files/lib/system/search/acp/ACPSearchResultList.class.php b/wcfsetup/install/files/lib/system/search/acp/ACPSearchResultList.class.php
index cdfeb98f90e..411b552d28a 100644
--- a/wcfsetup/install/files/lib/system/search/acp/ACPSearchResultList.class.php
+++ b/wcfsetup/install/files/lib/system/search/acp/ACPSearchResultList.class.php
@@ -10,6 +10,7 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements \Iterator<ACPSearchResult>
  */
 class ACPSearchResultList implements \Countable, \Iterator
 {
diff --git a/wcfsetup/install/files/lib/system/search/acp/AbstractCategorizedACPSearchResultProvider.class.php b/wcfsetup/install/files/lib/system/search/acp/AbstractCategorizedACPSearchResultProvider.class.php
index 758b4e3fbc0..23ef4242251 100644
--- a/wcfsetup/install/files/lib/system/search/acp/AbstractCategorizedACPSearchResultProvider.class.php
+++ b/wcfsetup/install/files/lib/system/search/acp/AbstractCategorizedACPSearchResultProvider.class.php
@@ -90,6 +90,8 @@ protected function getTopCategory($categoryName)
 
     /**
      * Loads categories.
+     *
+     * @return void
      */
     protected function loadCategories()
     {
@@ -99,7 +101,7 @@ protected function loadCategories()
         }
 
         // read categories
-        /** @var DatabaseObjectList $categoryList */
+        /** @var DatabaseObjectList<DatabaseObject> $categoryList */
         $categoryList = new $this->listClassName();
         $categoryList->readObjects();
 
@@ -110,10 +112,13 @@ protected function loadCategories()
             }
 
             // save level 1 categories
+            // @phpstan-ignore property.notFound
             if ($category->parentCategoryName == '') {
+                // @phpstan-ignore property.notFound
                 $this->topCategories[] = $category->categoryName;
             }
 
+            // @phpstan-ignore property.notFound
             $this->categories[$category->categoryName] = $category;
         }
 
diff --git a/wcfsetup/install/files/lib/system/search/acp/UserGroupOptionACPSearchResultProvider.class.php b/wcfsetup/install/files/lib/system/search/acp/UserGroupOptionACPSearchResultProvider.class.php
index bd7e61b136a..afbe0484db2 100644
--- a/wcfsetup/install/files/lib/system/search/acp/UserGroupOptionACPSearchResultProvider.class.php
+++ b/wcfsetup/install/files/lib/system/search/acp/UserGroupOptionACPSearchResultProvider.class.php
@@ -24,6 +24,9 @@ class UserGroupOptionACPSearchResultProvider extends AbstractCategorizedACPSearc
      */
     protected $listClassName = UserGroupOptionCategoryList::class;
 
+    /**
+     * @var list<string>
+     */
     private array $restrictedOptionNames = [
         'admin.configuration.package.canUpdatePackage',
         'admin.configuration.package.canEditServer',
diff --git a/wcfsetup/install/files/lib/system/search/exception/SearchFailed.class.php b/wcfsetup/install/files/lib/system/search/exception/SearchFailed.class.php
index e0ed1663d13..ae895e4388d 100644
--- a/wcfsetup/install/files/lib/system/search/exception/SearchFailed.class.php
+++ b/wcfsetup/install/files/lib/system/search/exception/SearchFailed.class.php
@@ -13,7 +13,7 @@
  */
 final class SearchFailed extends \RuntimeException
 {
-    public function __construct($message, ?\Throwable $previous = null)
+    public function __construct(string $message, ?\Throwable $previous = null)
     {
         parent::__construct($message, 0, $previous);
     }
diff --git a/wcfsetup/install/files/lib/system/search/mysql/MysqlSearchEngine.class.php b/wcfsetup/install/files/lib/system/search/mysql/MysqlSearchEngine.class.php
index adf9b31ce9d..0b5e22e66ed 100644
--- a/wcfsetup/install/files/lib/system/search/mysql/MysqlSearchEngine.class.php
+++ b/wcfsetup/install/files/lib/system/search/mysql/MysqlSearchEngine.class.php
@@ -23,6 +23,7 @@
 class MysqlSearchEngine extends AbstractSearchEngine
 {
     /**
+     * @var int
      * @deprecated 5.4 - This property is used for the deprecated getFulltextMinimumWordLength().
      */
     protected $ftMinWordLen;
@@ -179,6 +180,9 @@ public function getInnerJoin(
      * - `test -foo bar` becomes `+test* -foo +bar*`
      * - `test <foo bar` becomes `+test* <foo* +bar*`
      * - `test "foo bar"` becomes `+test* +"foo bar"`
+     *
+     * @param string $query
+     * @return string
      */
     protected function parseSearchQuery($query)
     {
@@ -335,6 +339,8 @@ protected function parseSearchQuery($query)
      * Word: |bar|
      * Word: |)|
      *
+     * @param string $query
+     * @return iterable<array{0: string, 1: string, 2: string}>
      * @see https://dev.mysql.com/doc/refman/8.0/en/fulltext-boolean.html
      * @see https://github.com/mysql/mysql-server/blob/ee4455a33b10f1b1886044322e4893f587b319ed/storage/innobase/fts/fts0pars.y
      * @see https://github.com/mysql/mysql-server/blob/ee4455a33b10f1b1886044322e4893f587b319ed/storage/innobase/fts/fts0blex.l
@@ -546,6 +552,7 @@ protected function splitIntoTerms($query)
     }
 
     /**
+     * @return int
      * @deprecated 5.4 - This method was required for use in parseSearchQuery().
      */
     protected function getFulltextMinimumWordLength()
diff --git a/wcfsetup/install/files/lib/system/session/ACPSessionFactory.class.php b/wcfsetup/install/files/lib/system/session/ACPSessionFactory.class.php
index 56ff9cbe63c..073ca0c6896 100644
--- a/wcfsetup/install/files/lib/system/session/ACPSessionFactory.class.php
+++ b/wcfsetup/install/files/lib/system/session/ACPSessionFactory.class.php
@@ -15,17 +15,21 @@
 class ACPSessionFactory
 {
     /**
+     * @var string
      * @deprecated 5.4 - This property is not read any longer.
      */
     protected $cookieSuffix = 'acp_';
 
     /**
+     * @var string
      * @deprecated 5.4 - This property is not read any longer.
      */
     protected $sessionEditor = ACPSessionEditor::class;
 
     /**
      * Loads the object of the active session.
+     *
+     * @return void
      */
     public function load()
     {
@@ -45,6 +49,7 @@ public function load()
     }
 
     /**
+     * @return bool
      * @deprecated 5.4 - Sessions are fully managed by SessionHandler.
      */
     public function hasValidCookie()
@@ -54,6 +59,8 @@ public function hasValidCookie()
 
     /**
      * Initializes the session system.
+     *
+     * @return void
      */
     protected function init()
     {
diff --git a/wcfsetup/install/files/lib/system/session/AbstractSessionHandler.class.php b/wcfsetup/install/files/lib/system/session/AbstractSessionHandler.class.php
index 521864fcc2d..c8dc0f63509 100644
--- a/wcfsetup/install/files/lib/system/session/AbstractSessionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/session/AbstractSessionHandler.class.php
@@ -43,6 +43,8 @@ public function __get($key)
 
     /**
      * Initializes this session.
+     *
+     * @return void
      */
     abstract protected function initSession();
 }
diff --git a/wcfsetup/install/files/lib/system/session/Session.class.php b/wcfsetup/install/files/lib/system/session/Session.class.php
index ff5fe11872e..fbb8ee48a3d 100644
--- a/wcfsetup/install/files/lib/system/session/Session.class.php
+++ b/wcfsetup/install/files/lib/system/session/Session.class.php
@@ -16,14 +16,14 @@
 final class Session
 {
     /**
-     * @var array
+     * @var array<string, mixed>
      */
-    private $data;
+    private array $data;
 
     private UserAgent $userAgent;
 
     /**
-     * Session constructor.
+     * @param array<string, mixed> $data
      */
     public function __construct(array $data)
     {
diff --git a/wcfsetup/install/files/lib/system/session/SessionHandler.class.php b/wcfsetup/install/files/lib/system/session/SessionHandler.class.php
index 2f54a478aee..d1e819ae593 100644
--- a/wcfsetup/install/files/lib/system/session/SessionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/session/SessionHandler.class.php
@@ -66,26 +66,21 @@ final class SessionHandler extends SingletonFactory
 
     /**
      * language id for active user
-     * @var int
      */
-    private $languageID = 0;
+    private int $languageID = 0;
 
-    /**
-     * @var string
-     */
     private string $sessionID;
 
     private ?LegacySession $legacySession = null;
 
     /**
      * user object
-     * @var User
      */
     private User $user;
 
     /**
      * session variables
-     * @var array
+     * @var array<string, mixed>
      */
     private $variables = [];
 
@@ -100,7 +95,7 @@ final class SessionHandler extends SingletonFactory
      * list of names of permissions only available for users
      * @var string[]
      */
-    private $usersOnlyPermissions = [];
+    private array $usersOnlyPermissions = [];
 
     private string $xsrfToken;
 
@@ -182,6 +177,8 @@ protected function init()
      * Parses the session cookie value, returning an array with the stored fields.
      *
      * The return array is guaranteed to have a `sessionId` key.
+     *
+     * @return array{sessionId: string}&array<string, mixed>
      */
     private function parseCookie(string $value): array
     {
@@ -220,6 +217,7 @@ private function parseCookie(string $value): array
     /**
      * Extracts the data from the session cookie.
      *
+     * @return array{sessionId: string}&array<string, mixed>
      * @see SessionHandler::parseCookie()
      * @since 5.4
      */
@@ -253,6 +251,8 @@ private function getParsedCookieData(): ?array
 
     /**
      * Returns the session ID stored in the session cookie or `null`.
+     *
+     * @param ?(array{sessionId: string}&array<string, mixed>) $cookieData
      */
     private function getSessionIdFromCookie(?array $cookieData): ?string
     {
@@ -307,7 +307,7 @@ public function hasValidCookie(): bool
     /**
      * @deprecated 5.4 - Sessions are managed automatically. Use loadFromCookie().
      */
-    public function load($sessionEditorClassName, $sessionID)
+    public function load(string $sessionEditorClassName, string $sessionID): void
     {
         $hasSession = false;
         if (!empty($sessionID)) {
@@ -322,7 +322,7 @@ public function load($sessionEditorClassName, $sessionID)
     /**
      * Loads the session matching the session cookie.
      */
-    public function loadFromCookie()
+    public function loadFromCookie(): void
     {
         $cookieData = $this->getParsedCookieData();
         $sessionID = $this->getSessionIdFromCookie($cookieData);
@@ -341,6 +341,8 @@ public function loadFromCookie()
 
     /**
      * Refreshes the session cookie, extending the expiry.
+     *
+     * @param array{timestep?: int} $cookieData
      */
     private function maybeRefreshCookie(array $cookieData): void
     {
@@ -365,10 +367,11 @@ private function maybeRefreshCookie(array $cookieData): void
     /**
      * Initializes session system.
      */
-    public function initSession()
+    public function initSession(): void
     {
         // assign language
-        $this->languageID = $this->getVar('languageID') ?: $this->user->languageID;
+        $languageID = $this->getVar('languageID') ?: $this->user->languageID;
+        $this->languageID = $languageID ?: 0;
 
         // https://github.com/WoltLab/WCF/issues/2568
         if ($this->getVar('__wcfIsFirstVisit') === true) {
@@ -380,7 +383,7 @@ public function initSession()
     /**
      * Disables update on shutdown.
      */
-    public function disableUpdate()
+    public function disableUpdate(): void
     {
         $this->doNotUpdate = true;
     }
@@ -704,10 +707,8 @@ private function createLegacySession(): LegacySession
 
     /**
      * Returns the value of the permission with the given name.
-     *
-     * @return  mixed       permission value
      */
-    public function getPermission(string $permission)
+    public function getPermission(string $permission): mixed
     {
         // check if a users only permission is checked for a guest and return
         // false if that is the case
@@ -727,10 +728,8 @@ public function getPermission(string $permission)
     /**
      * Returns true if a permission was set to 'Never'. This is required to preserve
      * compatibility, while preventing ACLs from overruling a 'Never' setting.
-     *
-     * @return      bool
      */
-    public function getNeverPermission(string $permission)
+    public function getNeverPermission(string $permission): bool
     {
         $this->loadGroupData();
 
@@ -744,7 +743,7 @@ public function getNeverPermission(string $permission)
      * @param string[] $permissions list of permissions where each one must pass
      * @throws  PermissionDeniedException
      */
-    public function checkPermissions(array $permissions)
+    public function checkPermissions(array $permissions): void
     {
         foreach ($permissions as $permission) {
             if (!$this->getPermission($permission)) {
@@ -756,7 +755,7 @@ public function checkPermissions(array $permissions)
     /**
      * Loads group data from cache.
      */
-    private function loadGroupData()
+    private function loadGroupData(): void
     {
         if ($this->groupData !== null) {
             return;
@@ -779,9 +778,10 @@ private function loadGroupData()
     }
 
     /**
+     * @return int[]
      * @deprecated 6.0 Use User::getLanguageIDs() instead.
      */
-    public function getLanguageIDs()
+    public function getLanguageIDs(): array
     {
         if (!$this->user->userID) {
             return [];
@@ -893,7 +893,7 @@ public function clearPendingUserChange(): void
      *
      * @param $hideSession if true, database won't be updated
      */
-    public function changeUser(User $user, bool $hideSession = false)
+    public function changeUser(User $user, bool $hideSession = false): void
     {
         $eventParameters = ['user' => $user, 'hideSession' => $hideSession];
 
@@ -912,7 +912,7 @@ public function changeUser(User $user, bool $hideSession = false)
 
         // reset caches
         $this->groupData = null;
-        $this->languageID = $this->user->languageID;
+        $this->languageID = $this->user->languageID ?: 0;
 
         // change language
         WCF::setLanguage($this->languageID ?: 0);
@@ -925,8 +925,6 @@ public function changeUser(User $user, bool $hideSession = false)
 
     /**
      * Changes the user stored in the session.
-     *
-     * @param User $user
      */
     private function changeUserVirtual(User $user): void
     {
@@ -1202,7 +1200,7 @@ public function update(): void
     /**
      * @deprecated 5.4 - This method is a noop. The lastActivityTime is always updated immediately after loading.
      */
-    public function keepAlive() {}
+    public function keepAlive(): void {}
 
     /**
      * Deletes this session and its related data.
@@ -1265,20 +1263,16 @@ public function deleteIfNew(): void
 
     /**
      * Returns currently active language id.
-     *
-     * @return  int
      */
-    public function getLanguageID()
+    public function getLanguageID(): int
     {
         return $this->languageID;
     }
 
     /**
      * Sets the currently active language id.
-     *
-     * @param int $languageID
      */
-    public function setLanguageID($languageID)
+    public function setLanguageID(int $languageID): void
     {
         $this->languageID = $languageID;
         $this->register('languageID', $this->languageID);
@@ -1290,7 +1284,7 @@ public function setLanguageID($languageID)
      * @param int[] $userIDs
      * @deprecated 6.1 see https://github.com/WoltLab/WCF/pull/3767
      */
-    public static function resetSessions(array $userIDs = [])
+    public static function resetSessions(array $userIDs = []): void
     {
         if (!empty($userIDs)) {
             UserStorageHandler::getInstance()->reset($userIDs, 'groupIDs');
@@ -1391,6 +1385,7 @@ public function deleteUserSession(string $sessionID): void
     /**
      * Returns the session variables.
      *
+     * @return array<string, mixed>
      * @since 6.1
      */
     public function getVariables(): array
diff --git a/wcfsetup/install/files/lib/system/setup/IFileHandler.class.php b/wcfsetup/install/files/lib/system/setup/IFileHandler.class.php
index 6bb11215c42..a1d6cb9d257 100644
--- a/wcfsetup/install/files/lib/system/setup/IFileHandler.class.php
+++ b/wcfsetup/install/files/lib/system/setup/IFileHandler.class.php
@@ -14,14 +14,16 @@ interface IFileHandler
     /**
      * Checks the overwriting rights of the given files.
      *
-     * @param array $files
+     * @param list<string> $files
+     * @return void
      */
     public function checkFiles(array $files);
 
     /**
      * Logs the given list of files.
      *
-     * @param array $files
+     * @param list<string> $files
+     * @return void
      */
     public function logFiles(array $files);
 }
diff --git a/wcfsetup/install/files/lib/system/setup/Installer.class.php b/wcfsetup/install/files/lib/system/setup/Installer.class.php
index 4a26148ebb9..97447ef7f0f 100644
--- a/wcfsetup/install/files/lib/system/setup/Installer.class.php
+++ b/wcfsetup/install/files/lib/system/setup/Installer.class.php
@@ -59,6 +59,8 @@ public function __construct($targetDir, $source, $fileHandler = null, $folder =
 
     /**
      * Creates the target directory if necessary.
+     *
+     * @return void
      */
     protected function createTargetDir()
     {
@@ -76,6 +78,7 @@ protected function createTargetDir()
      * Creates a directory in the target directory.
      *
      * @param string $dir
+     * @return void
      * @throws  SystemException
      */
     protected function createDir($dir)
@@ -96,6 +99,7 @@ protected function createDir($dir)
      * Touches a file in the target directory.
      *
      * @param string $file
+     * @return void
      */
     public function touchFile($file)
     {
@@ -109,6 +113,7 @@ public function touchFile($file)
      * @param string $file
      * @param int $index
      * @param Tar $tar
+     * @return void
      */
     protected function createFile($file, $index, Tar $tar)
     {
@@ -120,6 +125,8 @@ protected function createFile($file, $index, Tar $tar)
 
     /**
      * Starts the extracting of the files.
+     *
+     * @return void
      */
     protected function install()
     {
@@ -139,7 +146,7 @@ protected function install()
 
                 // remove leading slash
                 $file['filename'] = FileUtil::getRealPath(FileUtil::removeLeadingSlash($file['filename']));
-                if ($file['type'] == 'folder') {
+                if ($file['type'] === 'folder') {
                     // remove trailing slash
                     $directories[] = FileUtil::removeTrailingSlash($file['filename']);
                 } else {
@@ -192,7 +199,8 @@ protected function getTar($source)
     /**
      * Checks whether the given files overwriting locked existing files.
      *
-     * @param array $files
+     * @param list<string> $files
+     * @return void
      */
     protected function checkFiles(&$files)
     {
@@ -202,7 +210,8 @@ protected function checkFiles(&$files)
     /**
      * Logs the given files.
      *
-     * @param array $files
+     * @param list<string> $files
+     * @return void
      */
     protected function logFiles(&$files)
     {
@@ -213,6 +222,7 @@ protected function logFiles(&$files)
      * Makes a file or directory writeable.
      *
      * @param string $target
+     * @return void
      */
     protected function makeWriteable($target)
     {
diff --git a/wcfsetup/install/files/lib/system/setup/Uninstaller.class.php b/wcfsetup/install/files/lib/system/setup/Uninstaller.class.php
index 46c18eab03e..21d86808edd 100644
--- a/wcfsetup/install/files/lib/system/setup/Uninstaller.class.php
+++ b/wcfsetup/install/files/lib/system/setup/Uninstaller.class.php
@@ -54,6 +54,8 @@ public function __construct($targetDir, $files, $deleteEmptyTargetDir, $deleteEm
 
     /**
      * Checks if the target directory is a valid directory.
+     *
+     * @return bool
      */
     protected function checkTargetDir()
     {
@@ -80,6 +82,7 @@ protected function isEmpty($dir)
      * Deletes a file.
      *
      * @param string $file
+     * @return void
      */
     protected function deleteFile($file)
     {
@@ -90,6 +93,7 @@ protected function deleteFile($file)
      * Deletes a directory.
      *
      * @param string $dir
+     * @return void
      */
     protected function deleteDir($dir)
     {
@@ -98,6 +102,8 @@ protected function deleteDir($dir)
 
     /**
      * Starts the deletion of the files.
+     *
+     * @return void
      */
     protected function uninstall()
     {
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/AbstractSitemapObjectObjectType.class.php b/wcfsetup/install/files/lib/system/sitemap/object/AbstractSitemapObjectObjectType.class.php
index da889935317..b69baa5b836 100755
--- a/wcfsetup/install/files/lib/system/sitemap/object/AbstractSitemapObjectObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/AbstractSitemapObjectObjectType.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\sitemap\object;
 
 use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 
 /**
  * Abstract implementation of a sitemap object.
@@ -11,6 +12,10 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @template TDatabaseObjectList of DatabaseObjectList
+ * @implements ISitemapObjectObjectType<TDatabaseObject, TDatabaseObjectList>
  */
 abstract class AbstractSitemapObjectObjectType implements ISitemapObjectObjectType
 {
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/ArticleCategorySitemapObject.class.php b/wcfsetup/install/files/lib/system/sitemap/object/ArticleCategorySitemapObject.class.php
index 3724a744544..da54f7c8989 100644
--- a/wcfsetup/install/files/lib/system/sitemap/object/ArticleCategorySitemapObject.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/ArticleCategorySitemapObject.class.php
@@ -15,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @phpstan-ignore missingType.generics
  */
 class ArticleCategorySitemapObject extends AbstractSitemapObjectObjectType
 {
@@ -28,6 +30,7 @@ public function getObjectClass()
 
     /**
      * @inheritDoc
+     * @return CategoryList
      */
     public function getObjectList()
     {
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/ArticleSitemapObject.class.php b/wcfsetup/install/files/lib/system/sitemap/object/ArticleSitemapObject.class.php
index 9d8acd0f35b..8d8ad0ee354 100644
--- a/wcfsetup/install/files/lib/system/sitemap/object/ArticleSitemapObject.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/ArticleSitemapObject.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\sitemap\object;
 
 use wcf\data\article\content\ArticleContent;
+use wcf\data\article\content\ArticleContentList;
 use wcf\data\DatabaseObject;
 use wcf\data\page\PageCache;
 
@@ -13,6 +14,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractSitemapObjectObjectType<ArticleContent, ArticleContentList>
  */
 class ArticleSitemapObject extends AbstractSitemapObjectObjectType
 {
@@ -29,7 +32,6 @@ public function getObjectClass()
      */
     public function canView(DatabaseObject $object)
     {
-        /** @var ArticleContent $object */
         return $object->getArticle()->canRead();
     }
 
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/ISitemapObjectObjectType.class.php b/wcfsetup/install/files/lib/system/sitemap/object/ISitemapObjectObjectType.class.php
index e0856f3a628..5a1bf1d79e5 100755
--- a/wcfsetup/install/files/lib/system/sitemap/object/ISitemapObjectObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/ISitemapObjectObjectType.class.php
@@ -12,27 +12,30 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @template TDatabaseObjectList of DatabaseObjectList
  */
 interface ISitemapObjectObjectType
 {
     /**
      * Returns the DatabaseObject class name for the sitemap object.
      *
-     * @return  string
+     * @return string
      */
     public function getObjectClass();
 
     /**
      * Returns the DatabaseObjectList class name for the sitemap object.
      *
-     * @return  string
+     * @return string
      */
     public function getObjectListClass();
 
     /**
      * Returns the DatabaseObjectList for the sitemap object.
      *
-     * @return  DatabaseObjectList
+     * @return TDatabaseObjectList
      */
     public function getObjectList();
 
@@ -40,22 +43,22 @@ public function getObjectList();
      * Returns the database column, which represents the last modified date.
      * If there isn't any column, this method should return `null`.
      *
-     * @return  string|null
+     * @return ?string
      */
     public function getLastModifiedColumn();
 
     /**
      * Returns the permission for a guest to view a certain object for this object type.
      *
-     * @param DatabaseObject $object
-     * @return  bool
+     * @param TDatabaseObject $object
+     * @return bool
      */
     public function canView(DatabaseObject $object);
 
     /**
      * Checks the requirements (e.g. module options) for this object type.
      *
-     * @return  bool
+     * @return bool
      */
     public function isAvailableType();
 }
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/MultilingualPageSitemapObject.class.php b/wcfsetup/install/files/lib/system/sitemap/object/MultilingualPageSitemapObject.class.php
index 2e2b11d34b6..24f42cf3289 100644
--- a/wcfsetup/install/files/lib/system/sitemap/object/MultilingualPageSitemapObject.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/MultilingualPageSitemapObject.class.php
@@ -18,6 +18,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractSitemapObjectObjectType<PageContent, PageContentList>
  */
 class MultilingualPageSitemapObject extends AbstractSitemapObjectObjectType
 {
@@ -34,7 +36,6 @@ public function getObjectClass()
      */
     public function getObjectList()
     {
-        /** @var PageContentList $pageList */
         $pageList = parent::getObjectList();
 
         $pageList->sqlConditionJoins = '
@@ -57,7 +58,6 @@ public function getObjectList()
      */
     public function canView(DatabaseObject $object)
     {
-        /** @var PageContent $object */
         $page = new Page($object->pageID);
 
         if ($page->requireObjectID) {
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/SimplePageSitemapObject.class.php b/wcfsetup/install/files/lib/system/sitemap/object/SimplePageSitemapObject.class.php
index 0404572ffca..38ef09290ea 100644
--- a/wcfsetup/install/files/lib/system/sitemap/object/SimplePageSitemapObject.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/SimplePageSitemapObject.class.php
@@ -16,6 +16,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractSitemapObjectObjectType<Page, PageList>
  */
 class SimplePageSitemapObject extends AbstractSitemapObjectObjectType
 {
@@ -32,7 +34,6 @@ public function getObjectClass()
      */
     public function getObjectList()
     {
-        /** @var PageList $pageList */
         $pageList = parent::getObjectList();
         $pageList->getConditionBuilder()->add('isMultilingual = ?', [0]);
         $pageList->getConditionBuilder()->add('page.allowSpidersToIndex = ?', [1]);
@@ -45,8 +46,6 @@ public function getObjectList()
      */
     public function canView(DatabaseObject $object)
     {
-        \assert($object instanceof Page);
-
         if ($object->requireObjectID) {
             return false;
         }
diff --git a/wcfsetup/install/files/lib/system/sitemap/object/UserSitemapObject.class.php b/wcfsetup/install/files/lib/system/sitemap/object/UserSitemapObject.class.php
index 1b6ad83cf25..eb15542043f 100755
--- a/wcfsetup/install/files/lib/system/sitemap/object/UserSitemapObject.class.php
+++ b/wcfsetup/install/files/lib/system/sitemap/object/UserSitemapObject.class.php
@@ -4,6 +4,7 @@
 
 use wcf\data\page\PageCache;
 use wcf\data\user\User;
+use wcf\data\user\UserList;
 use wcf\system\WCF;
 
 /**
@@ -13,6 +14,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractSitemapObjectObjectType<User, UserList>
  */
 class UserSitemapObject extends AbstractSitemapObjectObjectType
 {
diff --git a/wcfsetup/install/files/lib/system/stat/AbstractStatDailyHandler.class.php b/wcfsetup/install/files/lib/system/stat/AbstractStatDailyHandler.class.php
index 20fa2ae83a6..322ead46324 100644
--- a/wcfsetup/install/files/lib/system/stat/AbstractStatDailyHandler.class.php
+++ b/wcfsetup/install/files/lib/system/stat/AbstractStatDailyHandler.class.php
@@ -74,6 +74,7 @@ public function getFormattedCounter($counter)
      * Adds additional conditions to the given condition builder.
      *
      * @param PreparedStatementConditionBuilder $conditionBuilder
+     * @return void
      * @since   3.1
      */
     protected function addConditions(PreparedStatementConditionBuilder $conditionBuilder)
diff --git a/wcfsetup/install/files/lib/system/stat/IStatDailyHandler.class.php b/wcfsetup/install/files/lib/system/stat/IStatDailyHandler.class.php
index b90a37930ee..ae9d35cd166 100644
--- a/wcfsetup/install/files/lib/system/stat/IStatDailyHandler.class.php
+++ b/wcfsetup/install/files/lib/system/stat/IStatDailyHandler.class.php
@@ -15,7 +15,7 @@ interface IStatDailyHandler
      * Returns the stats.
      *
      * @param int $date
-     * @return  array
+     * @return array{counter: int, total: int}
      */
     public function getData($date);
 
diff --git a/wcfsetup/install/files/lib/system/style/FontAwesomeIcon.class.php b/wcfsetup/install/files/lib/system/style/FontAwesomeIcon.class.php
index ca3a20f1f20..b37d3fa1650 100644
--- a/wcfsetup/install/files/lib/system/style/FontAwesomeIcon.class.php
+++ b/wcfsetup/install/files/lib/system/style/FontAwesomeIcon.class.php
@@ -21,6 +21,8 @@ final class FontAwesomeIcon implements IFontAwesomeIcon, \Stringable
     /**
      * Uses the icon name as the key and a boolean value that
      * indicates that an icon has a non-solid variant.
+     *
+     * @var array<string, bool>
      */
     private static array $icons;
 
diff --git a/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php b/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
index fec130f974e..08fbfc371de 100644
--- a/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
+++ b/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
@@ -331,6 +331,8 @@ public function compile(Style $style): void
      * Builds the preload manifest from the given iterable containing
      * preload requests.
      *
+     * @param iterable<array{filename: string, as: string, crossorigin: bool, type: ?string}> $requests
+     * @return array{http: list<string>, html: list<string>}
      * @see StyleCompiler::extractPreloadRequests()
      * @since 5.4
      */
@@ -370,6 +372,7 @@ private function buildPreloadManifest(iterable $requests): array
     /**
      * Extracts preload requests from the given CSS string.
      *
+     * @return iterable<array{filename: string, as: string, crossorigin: bool, type: ?string}>
      * @since 5.4
      */
     private function extractPreloadRequests(string $css): iterable
@@ -741,6 +744,8 @@ private function convertToRtl(string $css): string
 
     /**
      * Writes the given css into the file with the given prefix.
+     *
+     * @param ?array{http: list<string>, html: list<string>} $preloadManifest
      */
     private function writeCss(string $filePrefix, string $css, ?array $preloadManifest = null): void
     {
diff --git a/wcfsetup/install/files/lib/system/style/StyleHandler.class.php b/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
index 8657ae7fd33..a9ec91bd326 100644
--- a/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
+++ b/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
@@ -23,7 +23,7 @@ class StyleHandler extends SingletonFactory
 {
     /**
      * style information cache
-     * @var array
+     * @var array{}|array{default: int, styles: array<int, Style>}
      */
     protected $cache = [];
 
@@ -89,6 +89,7 @@ public function getStyle()
      *
      * @param int $styleID
      * @param bool $ignorePermissions
+     * @return void
      * @throws  SystemException
      */
     public function changeStyle($styleID = 0, $ignorePermissions = false)
@@ -174,6 +175,7 @@ public function getStylesheet($isACP = false)
      * Resets stylesheet for given style.
      *
      * @param Style $style
+     * @return void
      */
     public function resetStylesheet(Style $style)
     {
@@ -201,6 +203,7 @@ public function countStyles()
      * Resets all stylesheets.
      *
      * @param bool $resetACP
+     * @return void
      */
     public static function resetStylesheets($resetACP = true)
     {
@@ -271,6 +274,8 @@ public function showColorSchemeSelector(): bool
     }
 
     /**
+     * @param boolean $toJSON
+     * @return array{}|string
      * @deprecated 6.0 Unsupported, this exists temporarily for development purposes.
      */
     public function getIcons($toJSON = false)
diff --git a/wcfsetup/install/files/lib/system/style/exception/FontDownloadFailed.class.php b/wcfsetup/install/files/lib/system/style/exception/FontDownloadFailed.class.php
index 76c841763ed..89ea61aa614 100644
--- a/wcfsetup/install/files/lib/system/style/exception/FontDownloadFailed.class.php
+++ b/wcfsetup/install/files/lib/system/style/exception/FontDownloadFailed.class.php
@@ -12,11 +12,12 @@
  */
 class FontDownloadFailed extends \Exception
 {
+    private string $reason = '';
+
     /**
-     * @var string
+     * @param string $message
+     * @param string $reason
      */
-    private $reason = '';
-
     public function __construct($message, $reason = '', ?\Throwable $previous = null)
     {
         parent::__construct($message, 0, $previous);
diff --git a/wcfsetup/install/files/lib/system/tagging/AbstractCombinedTaggable.class.php b/wcfsetup/install/files/lib/system/tagging/AbstractCombinedTaggable.class.php
index 5fedf864873..2e7a4d75a38 100644
--- a/wcfsetup/install/files/lib/system/tagging/AbstractCombinedTaggable.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/AbstractCombinedTaggable.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\tagging;
 
+use wcf\data\DatabaseObjectList;
 use wcf\data\tag\Tag;
 
 /**
@@ -11,6 +12,10 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
+ *
+ * @template T of DatabaseObjectList
+ * @extends AbstractTaggable<T>
+ * @implements ICombinedTaggable<T>
  */
 abstract class AbstractCombinedTaggable extends AbstractTaggable implements ICombinedTaggable
 {
diff --git a/wcfsetup/install/files/lib/system/tagging/AbstractTaggable.class.php b/wcfsetup/install/files/lib/system/tagging/AbstractTaggable.class.php
index fb80944aa59..5bc7a2929c6 100644
--- a/wcfsetup/install/files/lib/system/tagging/AbstractTaggable.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/AbstractTaggable.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\tagging;
 
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\AbstractObjectTypeProcessor;
 
 /**
@@ -10,6 +11,9 @@
  * @author  Matthias Schmidt
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
+ * @implements ITaggable<T>
  */
 abstract class AbstractTaggable extends AbstractObjectTypeProcessor implements ITaggable
 {
diff --git a/wcfsetup/install/files/lib/system/tagging/ICombinedTaggable.class.php b/wcfsetup/install/files/lib/system/tagging/ICombinedTaggable.class.php
index 17fd9da2bd5..2b95af4f1e8 100644
--- a/wcfsetup/install/files/lib/system/tagging/ICombinedTaggable.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/ICombinedTaggable.class.php
@@ -13,6 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
+ *
+ * @template T of DatabaseObjectList
+ * @extends ITaggable<T>
  */
 interface ICombinedTaggable extends ITaggable
 {
@@ -20,8 +23,8 @@ interface ICombinedTaggable extends ITaggable
      * Returns a list of tagged objects that match all provided tags.
      *
      * @param Tag[] $tags
-     * @return DatabaseObjectList
-     * @since   5.2
+     * @return T
+     * @since 5.2
      */
     public function getObjectListFor(array $tags);
 }
diff --git a/wcfsetup/install/files/lib/system/tagging/ITaggable.class.php b/wcfsetup/install/files/lib/system/tagging/ITaggable.class.php
index a598ec76658..cd563f36ed8 100644
--- a/wcfsetup/install/files/lib/system/tagging/ITaggable.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/ITaggable.class.php
@@ -11,14 +11,15 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
  */
 interface ITaggable
 {
     /**
      * Returns a list of tagged objects.
      *
-     * @param Tag $tag
-     * @return  DatabaseObjectList
+     * @return T
      * @deprecated 5.2
      */
     public function getObjectList(Tag $tag);
diff --git a/wcfsetup/install/files/lib/system/tagging/ITagged.class.php b/wcfsetup/install/files/lib/system/tagging/ITagged.class.php
index 07d4eab2c65..09244e87308 100644
--- a/wcfsetup/install/files/lib/system/tagging/ITagged.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/ITagged.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\tagging;
 
+use wcf\data\DatabaseObjectList;
 use wcf\data\IIDObject;
 
 /**
@@ -10,13 +11,15 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
  */
 interface ITagged extends IIDObject
 {
     /**
      * Returns the taggable type of this tagged object.
      *
-     * @return  ITaggable
+     * @return ITaggable<T>
      */
     public function getTaggable();
 }
diff --git a/wcfsetup/install/files/lib/system/tagging/TagCloud.class.php b/wcfsetup/install/files/lib/system/tagging/TagCloud.class.php
index 8d7a7e7d765..e0750053697 100644
--- a/wcfsetup/install/files/lib/system/tagging/TagCloud.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/TagCloud.class.php
@@ -57,6 +57,8 @@ public function __construct(array $languageIDs = [])
 
     /**
      * Loads the tag cloud cache.
+     *
+     * @return void
      */
     protected function loadCache()
     {
diff --git a/wcfsetup/install/files/lib/system/tagging/TagEngine.class.php b/wcfsetup/install/files/lib/system/tagging/TagEngine.class.php
index 565515a9565..8def7f454f1 100644
--- a/wcfsetup/install/files/lib/system/tagging/TagEngine.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/TagEngine.class.php
@@ -27,16 +27,25 @@ class TagEngine extends SingletonFactory
      *
      * @param string $objectType
      * @param int $objectID
-     * @param array $tags
+     * @param string[] $tags
      * @param int $languageID
      * @param bool $replace
+     * @return void
      */
     public function addObjectTags($objectType, $objectID, array $tags, $languageID, $replace = true)
     {
         $objectTypeID = $this->getObjectTypeID($objectType);
-        $tags = \array_unique(\array_reduce(ArrayUtil::trim(\array_map(static function ($tag) {
-            return \explode(',', $tag);
-        }, $tags)), 'array_merge', []));
+        $tags = \array_unique(
+            \array_reduce(
+                ArrayUtil::trim(
+                    \array_map(static function ($tag) {
+                        return \explode(',', $tag);
+                    }, $tags)
+                ),
+                'array_merge',
+                []
+            )
+        );
 
         // remove tags prior to apply the new ones (prevents duplicate entries)
         if ($replace) {
@@ -108,6 +117,7 @@ public function addObjectTags($objectType, $objectID, array $tags, $languageID,
      * @param string $objectType
      * @param int $objectID
      * @param int $languageID
+     * @return void
      */
     public function deleteObjectTags($objectType, $objectID, $languageID = null)
     {
@@ -136,6 +146,7 @@ public function deleteObjectTags($objectType, $objectID, $languageID = null)
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public function deleteObjects($objectType, array $objectIDs)
     {
@@ -172,7 +183,7 @@ public function getObjectTags($objectType, $objectID, array $languageIDs = [])
      * @param string $objectType
      * @param int[] $objectIDs
      * @param int[] $languageIDs
-     * @return  array
+     * @return array<int, array<int, Tag>>
      */
     public function getObjectsTags($objectType, array $objectIDs, array $languageIDs = [])
     {
@@ -289,7 +300,7 @@ public function getTagIDs($tags)
      *
      * @param string $objectType
      * @param Tag[] $tags
-     * @return array
+     * @return array{sql: string, parameters: mixed[]}
      * @since   5.2
      */
     public function getSubselectForObjectsByTags($objectType, array $tags)
diff --git a/wcfsetup/install/files/lib/system/tagging/TaggableArticle.class.php b/wcfsetup/install/files/lib/system/tagging/TaggableArticle.class.php
index f43b26819ee..32c3aef0904 100644
--- a/wcfsetup/install/files/lib/system/tagging/TaggableArticle.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/TaggableArticle.class.php
@@ -11,6 +11,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
+ *
+ * @extends AbstractCombinedTaggable<TaggedArticleList>
  */
 class TaggableArticle extends AbstractCombinedTaggable
 {
diff --git a/wcfsetup/install/files/lib/system/tagging/TypedTagCloud.class.php b/wcfsetup/install/files/lib/system/tagging/TypedTagCloud.class.php
index 93638a2d329..5159429cd69 100644
--- a/wcfsetup/install/files/lib/system/tagging/TypedTagCloud.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/TypedTagCloud.class.php
@@ -37,6 +37,8 @@ public function __construct($objectType, array $languageIDs = [])
 
     /**
      * Loads the tag cloud cache.
+     *
+     * @return void
      */
     protected function loadCache()
     {
diff --git a/wcfsetup/install/files/lib/system/tagging/command/SetSynonym.class.php b/wcfsetup/install/files/lib/system/tagging/command/SetSynonym.class.php
index a7e7771bd8b..9a0b63dd594 100644
--- a/wcfsetup/install/files/lib/system/tagging/command/SetSynonym.class.php
+++ b/wcfsetup/install/files/lib/system/tagging/command/SetSynonym.class.php
@@ -23,7 +23,7 @@ public function __construct(
         private readonly array $tags
     ) {}
 
-    public function __invoke()
+    public function __invoke(): void
     {
         $tagEditor = new TagEditor($this->mainTag);
 
diff --git a/wcfsetup/install/files/lib/system/template/ACPTemplateEngine.class.php b/wcfsetup/install/files/lib/system/template/ACPTemplateEngine.class.php
index 0b8b48629ac..983e1dac828 100644
--- a/wcfsetup/install/files/lib/system/template/ACPTemplateEngine.class.php
+++ b/wcfsetup/install/files/lib/system/template/ACPTemplateEngine.class.php
@@ -33,6 +33,7 @@ protected function init()
      * Deletes all compiled acp templates.
      *
      * @param string $compileDir
+     * @return void
      */
     public static function deleteCompiledACPTemplates($compileDir = '')
     {
diff --git a/wcfsetup/install/files/lib/system/template/TemplateCompiler.class.php b/wcfsetup/install/files/lib/system/template/TemplateCompiler.class.php
index ae0f5275a9b..ab59a386ce6 100644
--- a/wcfsetup/install/files/lib/system/template/TemplateCompiler.class.php
+++ b/wcfsetup/install/files/lib/system/template/TemplateCompiler.class.php
@@ -19,7 +19,8 @@ class TemplateCompiler extends TemplateScriptingCompiler
      * @param string $templateName
      * @param string $sourceContent
      * @param string $compiledFilename
-     * @param array $metaData
+     * @param array<string, mixed> $metaData
+     * @return void
      */
     public function compile($templateName, $sourceContent, $compiledFilename, $metaData)
     {
@@ -46,7 +47,8 @@ public function compile($templateName, $sourceContent, $compiledFilename, $metaD
      *
      * @param string $templateName
      * @param string $filename
-     * @param string $content
+     * @param mixed[] $content
+     * @return void
      */
     public function saveMetaData($templateName, $filename, $content)
     {
diff --git a/wcfsetup/install/files/lib/system/template/TemplateEngine.class.php b/wcfsetup/install/files/lib/system/template/TemplateEngine.class.php
index bfc318f6215..dee1cb60485 100755
--- a/wcfsetup/install/files/lib/system/template/TemplateEngine.class.php
+++ b/wcfsetup/install/files/lib/system/template/TemplateEngine.class.php
@@ -4,6 +4,7 @@
 
 use Laminas\Diactoros\Stream;
 use Psr\Http\Message\StreamInterface;
+use wcf\data\template\group\TemplateGroup;
 use wcf\data\template\Template;
 use wcf\system\cache\builder\TemplateGroupCacheBuilder;
 use wcf\system\cache\builder\TemplateListenerCodeCacheBuilder;
@@ -11,6 +12,7 @@
 use wcf\system\exception\SystemException;
 use wcf\system\Regex;
 use wcf\system\SingletonFactory;
+use wcf\system\template\plugin\IBlockTemplatePlugin;
 use wcf\system\template\plugin\IPrefilterTemplatePlugin;
 use wcf\system\WCF;
 use wcf\util\DirectoryUtil;
@@ -187,7 +189,7 @@ class TemplateEngine extends SingletonFactory
 
     /**
      * cached list of known template groups
-     * @var array
+     * @var array<int, TemplateGroup>
      */
     protected $templateGroupCache = [];
 
@@ -240,8 +242,14 @@ class TemplateEngine extends SingletonFactory
      */
     protected $environment = 'user';
 
+    /**
+     * @var array<string, IBlockTemplatePlugin>
+     */
     protected $pluginObjects = [];
 
+    /**
+     * @var list<array{0: string, 1: list<string>}>
+     */
     protected $tagStack = [];
 
     private int $sharedTemplateGroupID;
@@ -264,6 +272,7 @@ protected function init()
      *
      * @param string $abbreviation
      * @param string $templatePath
+     * @return void
      */
     public function addApplication($abbreviation, $templatePath)
     {
@@ -274,6 +283,7 @@ public function addApplication($abbreviation, $templatePath)
      * Sets active language id.
      *
      * @param int $languageID
+     * @return void
      */
     public function setLanguageID($languageID)
     {
@@ -282,6 +292,8 @@ public function setLanguageID($languageID)
 
     /**
      * Assigns some system variables.
+     *
+     * @return void
      */
     protected function assignSystemVariables()
     {
@@ -300,6 +312,7 @@ protected function assignSystemVariables()
      *
      * @param mixed $variable
      * @param mixed $value
+     * @return void
      */
     public function assign($variable, $value = '')
     {
@@ -321,6 +334,7 @@ public function assign($variable, $value = '')
      *
      * @param mixed $variable
      * @param mixed $value
+     * @return void
      */
     public function append($variable, $value = '')
     {
@@ -357,6 +371,7 @@ public function append($variable, $value = '')
      *
      * @param mixed $variable
      * @param mixed $value
+     * @return void
      */
     public function prepend($variable, $value = '')
     {
@@ -393,6 +408,7 @@ public function prepend($variable, $value = '')
      *
      * @param string $variable
      * @param mixed $value
+     * @return void
      */
     public function assignByRef($variable, &$value)
     {
@@ -403,6 +419,9 @@ public function assignByRef($variable, &$value)
 
     /**
      * Clears an assignment of template variables.
+     *
+     * @param string[] $variables
+     * @return void
      */
     public function clearAssign(array $variables)
     {
@@ -414,6 +433,8 @@ public function clearAssign(array $variables)
     /**
      * Clears assignment of all template variables. This should not be called
      * during runtime as it could leed to an unexpected behaviour.
+     *
+     * @return void
      */
     public function clearAllAssign()
     {
@@ -426,6 +447,7 @@ public function clearAllAssign()
      * @param string $templateName
      * @param string $application
      * @param bool $sendHeaders
+     * @return void
      */
     public function display($templateName, $application = 'wcf', $sendHeaders = true)
     {
@@ -565,37 +587,37 @@ public function getMetaDataFilename($templateName)
      * @param string $sourceFilename
      * @param string $compiledFilename
      * @param string $application
-     * @param array $metaData
+     * @param mixed[] $metaData
      * @return  bool
      */
     protected function isCompiled($templateName, $sourceFilename, $compiledFilename, $application, array $metaData)
     {
         if ($this->forceCompile || !\file_exists($compiledFilename)) {
             return false;
-        } else {
-            $sourceMTime = @\filemtime($sourceFilename);
-            $compileMTime = @\filemtime($compiledFilename);
+        }
 
-            if ($sourceMTime >= $compileMTime) {
-                return false;
-            } else {
-                // check for meta data
-                if (!empty($metaData['include'])) {
-                    foreach ($metaData['include'] as $application => $includedTemplates) {
-                        foreach ($includedTemplates as $includedTemplate) {
-                            $includedTemplateFilename = $this->getSourceFilename($includedTemplate, $application);
-                            $includedMTime = @\filemtime($includedTemplateFilename);
-
-                            if ($includedMTime >= $compileMTime) {
-                                return false;
-                            }
-                        }
+        $sourceMTime = @\filemtime($sourceFilename);
+        $compileMTime = @\filemtime($compiledFilename);
+
+        if ($sourceMTime >= $compileMTime) {
+            return false;
+        }
+
+        // check for meta data
+        if (!empty($metaData['include'])) {
+            foreach ($metaData['include'] as $application => $includedTemplates) {
+                foreach ($includedTemplates as $includedTemplate) {
+                    $includedTemplateFilename = $this->getSourceFilename($includedTemplate, $application);
+                    $includedMTime = @\filemtime($includedTemplateFilename);
+
+                    if ($includedMTime >= $compileMTime) {
+                        return false;
                     }
                 }
-
-                return true;
             }
         }
+
+        return true;
     }
 
     /**
@@ -604,7 +626,8 @@ protected function isCompiled($templateName, $sourceFilename, $compiledFilename,
      * @param string $templateName
      * @param string $sourceFilename
      * @param string $compiledFilename
-     * @param array $metaData
+     * @param array{application: string, data: string[], filename: string} $metaData
+     * @return void
      */
     protected function compileTemplate($templateName, $sourceFilename, $compiledFilename, array $metaData)
     {
@@ -661,6 +684,8 @@ public function getPluginClassName($type, $tag)
 
     /**
      * Enables execution in sandbox.
+     *
+     * @return void
      */
     public function enableSandbox()
     {
@@ -673,6 +698,8 @@ public function enableSandbox()
 
     /**
      * Disables execution in sandbox.
+     *
+     * @return void
      */
     public function disableSandbox()
     {
@@ -690,7 +717,7 @@ public function disableSandbox()
      *
      * @param string $templateName
      * @param string $application
-     * @param array $variables
+     * @param array<string, mixed> $variables
      * @param bool $sandbox enables execution in sandbox
      * @return  string
      *
@@ -723,6 +750,7 @@ public function fetch($templateName, $application = 'wcf', array $variables = []
     /**
      * Returns the output of a template.
      *
+     * @param array<string, mixed> $variables
      * @since 6.2
      */
     public function render(string $application, string $templateName, array $variables): string
@@ -738,6 +766,7 @@ public function render(string $application, string $templateName, array $variabl
             \ob_start();
             $this->display($templateName, $application, false);
             $output = \ob_get_contents();
+            \assert($output !== false);
         } finally {
             \ob_end_clean();
         }
@@ -750,6 +779,7 @@ public function render(string $application, string $templateName, array $variabl
     /**
      * Renders the template into a fresh PSR-7 StreamInterface.
      *
+     * @param array<string, mixed> $variables
      * @since 6.0
      */
     public function fetchStream(
@@ -797,7 +827,7 @@ public function fetchStream(
      * Executes a compiled template scripting source and returns the result.
      *
      * @param string $compiledSource
-     * @param array $variables
+     * @param array<string, mixed> $variables
      * @param bool $sandbox enables execution in sandbox
      * @return  string
      */
@@ -831,6 +861,7 @@ public function fetchString($compiledSource, array $variables = [], $sandbox = t
      * Deletes all compiled templates.
      *
      * @param string $compileDir
+     * @return void
      */
     public static function deleteCompiledTemplates($compileDir = '')
     {
@@ -866,6 +897,7 @@ public function getTemplateGroupID()
      * Sets the active template group id.
      *
      * @param int $templateGroupID
+     * @return void
      */
     public function setTemplateGroupID($templateGroupID)
     {
@@ -878,6 +910,8 @@ public function setTemplateGroupID($templateGroupID)
 
     /**
      * Loads cached template group information.
+     *
+     * @return void
      */
     protected function loadTemplateGroupCache()
     {
@@ -888,6 +922,7 @@ protected function loadTemplateGroupCache()
      * Registers prefilters.
      *
      * @param string[] $prefilters
+     * @return void
      */
     public function registerPrefilter(array $prefilters)
     {
@@ -900,6 +935,7 @@ public function registerPrefilter(array $prefilters)
      * Removes a prefilter by its internal name.
      *
      * @param string $name internal prefilter identifier
+     * @return void
      */
     public function removePrefilter($name)
     {
@@ -910,6 +946,7 @@ public function removePrefilter($name)
      * Sets the dir for the compiled templates.
      *
      * @param string $compileDir
+     * @return void
      * @throws  SystemException
      */
     public function setCompileDir($compileDir)
@@ -926,8 +963,9 @@ public function setCompileDir($compileDir)
      *
      * @param string $templateName
      * @param string $application
-     * @param array $variables
+     * @param array<string, mixed> $variables
      * @param bool $sandbox enables execution in sandbox
+     * @return void
      */
     protected function includeTemplate($templateName, $application, array $variables = [], $sandbox = true)
     {
@@ -965,6 +1003,8 @@ public function get($varname)
 
     /**
      * Loads template listener code.
+     *
+     * @return void
      */
     protected function loadTemplateListenerCode()
     {
@@ -1004,7 +1044,7 @@ public function getTemplateListenerCode($templateName, $eventName)
      *
      * @param string $templateName
      * @param string $filename
-     * @return  array|null
+     * @return mixed[]|null
      */
     protected function getMetaData($templateName, $filename)
     {
diff --git a/wcfsetup/install/files/lib/system/template/TemplateScriptingCompiler.class.php b/wcfsetup/install/files/lib/system/template/TemplateScriptingCompiler.class.php
index 070fea954d1..7d66d4969cb 100644
--- a/wcfsetup/install/files/lib/system/template/TemplateScriptingCompiler.class.php
+++ b/wcfsetup/install/files/lib/system/template/TemplateScriptingCompiler.class.php
@@ -206,7 +206,7 @@ class TemplateScriptingCompiler
 
     /**
      * stack used to compile the capture tag
-     * @var array
+     * @var list<array{name: string, variable: string, append: boolean}>
      */
     protected $captureStack = [];
 
@@ -273,10 +273,10 @@ public function __construct(TemplateEngine $template)
      *
      * @param string $identifier
      * @param string $sourceContent
-     * @param array $metaData
+     * @param array<string, string|null> $metaData
      * @param bool $isolated
-     * @return  array|bool
-     * @throws  SystemException
+     * @return array{meta: array{include: string[][]}, template: string}|bool
+     * @throws SystemException
      */
     public function compileString($identifier, $sourceContent, array $metaData = [], $isolated = false)
     {
@@ -393,7 +393,7 @@ public function compileString($identifier, $sourceContent, array $metaData = [],
      *
      * @param string $tag
      * @param string $identifier
-     * @param array $metaData
+     * @param string[] $metaData
      * @return  string
      * @throws  SystemException
      * @phpstan-impure
@@ -967,7 +967,7 @@ protected function compileForeachEndTag()
      *
      * @param string $includeTag
      * @param string $identifier
-     * @param array $metaData
+     * @param string[] $metaData
      * @return  string
      * @throws  SystemException
      */
@@ -1026,7 +1026,9 @@ protected function compileIncludeTag($includeTag, $identifier, array $metaData)
             unset($args['sandbox']);
         }
 
-        $sandbox = ($sandbox === 'true' || $sandbox === true || $sandbox == 1);
+        if (\is_string($sandbox)) {
+            $sandbox = $sandbox === 'true' || $sandbox === '1';
+        }
 
         $staticInclude = true;
         if (
@@ -1124,7 +1126,7 @@ protected function compileIncludeTag($includeTag, $identifier, array $metaData)
      *
      * @param string $tagArgs
      * @param string $tag
-     * @return  array
+     * @return array<string, string>
      * @throws  SystemException
      */
     public function parseTagArgs($tagArgs, $tag)
@@ -1177,7 +1179,7 @@ public function parseTagArgs($tagArgs, $tag)
      * Takes an array created by TemplateCompiler::parseTagArgs() and creates
      * a string.
      *
-     * @param array $args
+     * @param array<string, string> $args
      * @return  string      $args
      */
     public static function makeArgString($args)
@@ -1433,7 +1435,7 @@ protected function compileSimpleVariable($variable, $type = '', $allowConstants
     /**
      * Compiles a modifier tag and returns the compiled PHP code.
      *
-     * @param array $data
+     * @param array{className: string, parameter: list<string>}|array{name: string, parameter: list<string>} $data
      * @return  string
      */
     protected function compileModifier($data)
@@ -1889,6 +1891,8 @@ public function compileVariableTag($tag, $replaceQuotes = true)
 
     /**
      * Generates the regexp pattern.
+     *
+     * @return void
      */
     protected function buildPattern()
     {
diff --git a/wcfsetup/install/files/lib/system/template/plugin/CounterFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/CounterFunctionTemplatePlugin.class.php
index a74be2a27fb..25ec05e8e1e 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/CounterFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/CounterFunctionTemplatePlugin.class.php
@@ -19,7 +19,7 @@ class CounterFunctionTemplatePlugin implements IFunctionTemplatePlugin
 {
     /**
      * counter data
-     * @var array
+     * @var array<string, array{skip: int, direction: string, assign: ?string, print: bool, count: int}>
      */
     protected $counters = [];
 
diff --git a/wcfsetup/install/files/lib/system/template/plugin/CycleFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/CycleFunctionTemplatePlugin.class.php
index 2e7c60f06ac..fb3af0f3e08 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/CycleFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/CycleFunctionTemplatePlugin.class.php
@@ -19,7 +19,7 @@ class CycleFunctionTemplatePlugin implements IFunctionTemplatePlugin
 {
     /**
      * cycle data
-     * @var array
+     * @var array<string, string|array<string, string|int>>
      */
     protected $cycles = [];
 
diff --git a/wcfsetup/install/files/lib/system/template/plugin/HascontentPrefilterTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/HascontentPrefilterTemplatePlugin.class.php
index 96356617542..01c0eea0eac 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/HascontentPrefilterTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/HascontentPrefilterTemplatePlugin.class.php
@@ -47,7 +47,7 @@ public function execute($templateName, $sourceContent, TemplateScriptingCompiler
      * the content during runtime, safely determining whether content is empty
      * or not.
      *
-     * @param array $matches
+     * @param array{before: string, content: string, after: string, else?: string, assign?: string} $matches
      * @return  string
      */
     protected static function replaceContentCallback(array $matches)
diff --git a/wcfsetup/install/files/lib/system/template/plugin/HtmlOptionsFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/HtmlOptionsFunctionTemplatePlugin.class.php
index 2e952dade4b..3f3c053553d 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/HtmlOptionsFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/HtmlOptionsFunctionTemplatePlugin.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\template\plugin;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\system\exception\SystemException;
 use wcf\system\template\TemplateEngine;
@@ -106,7 +107,7 @@ public function execute($tagArgs, TemplateEngine $tplObj)
      * Makes the HTML for an option group.
      *
      * @param ?string $key
-     * @param array|DatabaseObjectList $values
+     * @param array<string, string|array<string, string>>|DatabaseObjectList<DatabaseObject> $values
      * @return  string
      */
     protected function makeOptionGroup($key, $values)
@@ -118,6 +119,7 @@ protected function makeOptionGroup($key, $values)
 
         if ($values instanceof DatabaseObjectList) {
             foreach ($values as $childKey => $value) {
+                // @phpstan-ignore argument.type, argument.type
                 $html .= $this->makeOption($childKey, $value);
             }
         } else {
diff --git a/wcfsetup/install/files/lib/system/template/plugin/IBlockTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/IBlockTemplatePlugin.class.php
index dd634579cd0..9fd8e4f1565 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/IBlockTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/IBlockTemplatePlugin.class.php
@@ -16,7 +16,7 @@ interface IBlockTemplatePlugin
     /**
      * Executes this template block.
      *
-     * @param array $tagArgs
+     * @param array<string|int, mixed> $tagArgs
      * @param string $blockContent
      * @param TemplateEngine $tplObj
      * @return  string
@@ -26,8 +26,9 @@ public function execute($tagArgs, $blockContent, TemplateEngine $tplObj);
     /**
      * Initialises this template block.
      *
-     * @param array $tagArgs
+     * @param array<string|int, mixed> $tagArgs
      * @param TemplateEngine $tplObj
+     * @return void
      */
     public function init($tagArgs, TemplateEngine $tplObj);
 
diff --git a/wcfsetup/install/files/lib/system/template/plugin/ICompilerTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/ICompilerTemplatePlugin.class.php
index cdae58cb3e6..783c5cc4117 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/ICompilerTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/ICompilerTemplatePlugin.class.php
@@ -16,7 +16,7 @@ interface ICompilerTemplatePlugin
     /**
      * Executes the start tag of this compiler function.
      *
-     * @param array $tagArgs
+     * @param array<int|string, mixed> $tagArgs
      * @param TemplateScriptingCompiler $compiler
      * @return  string
      */
diff --git a/wcfsetup/install/files/lib/system/template/plugin/IFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/IFunctionTemplatePlugin.class.php
index f1a0c643a42..7b234700b9c 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/IFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/IFunctionTemplatePlugin.class.php
@@ -16,7 +16,7 @@ interface IFunctionTemplatePlugin
     /**
      * Executes this template function.
      *
-     * @param array $tagArgs
+     * @param array<int|string, mixed> $tagArgs
      * @param TemplateEngine $tplObj
      * @return  string
      */
diff --git a/wcfsetup/install/files/lib/system/template/plugin/IModifierTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/IModifierTemplatePlugin.class.php
index 510d9280ae5..d752ff03ae0 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/IModifierTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/IModifierTemplatePlugin.class.php
@@ -17,7 +17,7 @@ interface IModifierTemplatePlugin
     /**
      * Executes this modifier.
      *
-     * @param array $tagArgs
+     * @param array<int|string, mixed> $tagArgs
      * @param TemplateEngine $tplObj
      * @return  string
      */
diff --git a/wcfsetup/install/files/lib/system/template/plugin/PluralFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/PluralFunctionTemplatePlugin.class.php
index d32d16138f9..7c10984fd70 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/PluralFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/PluralFunctionTemplatePlugin.class.php
@@ -84,6 +84,8 @@ public function execute($tagArgs, TemplateEngine $tplObj)
      * This extra step is required because the existing implementation for
      * plurals resolved the category and then picked the appropriate value
      * itself.
+     *
+     * @param array<string|int, string> $values
      */
     private function createMessageFromValues(array $values): string
     {
diff --git a/wcfsetup/install/files/lib/system/trophy/condition/TrophyConditionHandler.class.php b/wcfsetup/install/files/lib/system/trophy/condition/TrophyConditionHandler.class.php
index 00d743d5dfc..259065e8d90 100644
--- a/wcfsetup/install/files/lib/system/trophy/condition/TrophyConditionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/trophy/condition/TrophyConditionHandler.class.php
@@ -66,6 +66,7 @@ public function getGroupedObjectTypes()
      * Assign trophies based on rules.
      *
      * @param int $maxAssigns
+     * @return void
      */
     public function assignTrophies($maxAssigns = 500)
     {
@@ -99,6 +100,7 @@ public function assignTrophies($maxAssigns = 500)
      * Revoke user trophies which are not longer fulfills the conditions.
      *
      * @param int $maxRevokes
+     * @return void
      * @since       5.2
      */
     public function revokeTrophies($maxRevokes = 500)
diff --git a/wcfsetup/install/files/lib/system/upload/DefaultUploadFileSaveStrategy.class.php b/wcfsetup/install/files/lib/system/upload/DefaultUploadFileSaveStrategy.class.php
index 0e83c05a723..6a79c6d800a 100644
--- a/wcfsetup/install/files/lib/system/upload/DefaultUploadFileSaveStrategy.class.php
+++ b/wcfsetup/install/files/lib/system/upload/DefaultUploadFileSaveStrategy.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\upload;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectEditor;
 use wcf\data\IDatabaseObjectAction;
 use wcf\data\IFile;
@@ -40,7 +41,7 @@ class DefaultUploadFileSaveStrategy implements IUploadFileSaveStrategy
 
     /**
      * additional data stored with the default file data
-     * @var array
+     * @var mixed[]
      */
     public $data = [];
 
@@ -56,7 +57,7 @@ class DefaultUploadFileSaveStrategy implements IUploadFileSaveStrategy
      * - bool rotateImages: if true, images are automatically rotated
      * - bool generateThumbnails: if true, thumbnails are automatically generated after saving file
      *
-     * @var array
+     * @var mixed[]
      */
     public $options = [];
 
@@ -64,8 +65,8 @@ class DefaultUploadFileSaveStrategy implements IUploadFileSaveStrategy
      * Creates a new instance of DefaultUploadFileSaveStrategy.
      *
      * @param string $actionClassName
-     * @param array $options
-     * @param array $data
+     * @param mixed[] $options
+     * @param mixed[] $data
      * @throws  ImplementationException
      * @throws  ParentClassException
      */
@@ -247,7 +248,7 @@ public function save(UploadFile $uploadFile)
                 }
 
                 if (!empty($updateData)) {
-                    /** @var DatabaseObjectEditor $editor */
+                    /** @var DatabaseObjectEditor<DatabaseObject> $editor */
                     $editor = new $this->editorClassName($object);
                     $editor->update($updateData);
                 }
@@ -258,12 +259,12 @@ public function save(UploadFile $uploadFile)
                     throw $e;
                 }
 
-                /** @var DatabaseObjectEditor $editor */
+                /** @var DatabaseObjectEditor<DatabaseObject> $editor */
                 $editor = new $this->editorClassName($object);
                 $editor->delete();
             }
         } else {
-            /** @var DatabaseObjectEditor $editor */
+            /** @var DatabaseObjectEditor<DatabaseObject> $editor */
             $editor = new $this->editorClassName($object);
             $editor->delete();
         }
@@ -276,7 +277,7 @@ public function save(UploadFile $uploadFile)
                     throw $e;
                 }
 
-                /** @var DatabaseObjectEditor $editor */
+                /** @var DatabaseObjectEditor<DatabaseObject> $editor */
                 $editor = new $this->editorClassName($object);
                 $editor->delete();
             }
@@ -287,6 +288,7 @@ public function save(UploadFile $uploadFile)
      * Generates thumbnails for the given file.
      *
      * @param IThumbnailFile $file
+     * @return void
      */
     public function generateThumbnails(IThumbnailFile $file)
     {
diff --git a/wcfsetup/install/files/lib/system/upload/IUploadFileSaveStrategy.class.php b/wcfsetup/install/files/lib/system/upload/IUploadFileSaveStrategy.class.php
index 887500124aa..3c4abcee61c 100644
--- a/wcfsetup/install/files/lib/system/upload/IUploadFileSaveStrategy.class.php
+++ b/wcfsetup/install/files/lib/system/upload/IUploadFileSaveStrategy.class.php
@@ -15,6 +15,7 @@ interface IUploadFileSaveStrategy
      * Saves the given file.
      *
      * @param UploadFile $uploadFile
+     * @return void
      */
     public function save(UploadFile $uploadFile);
 }
diff --git a/wcfsetup/install/files/lib/system/upload/UploadFile.class.php b/wcfsetup/install/files/lib/system/upload/UploadFile.class.php
index 1564dbe82e2..84c475e8796 100644
--- a/wcfsetup/install/files/lib/system/upload/UploadFile.class.php
+++ b/wcfsetup/install/files/lib/system/upload/UploadFile.class.php
@@ -55,7 +55,7 @@ class UploadFile
 
     /**
      * additional data for validation errors
-     * @var array
+     * @var mixed[]
      */
     protected $validationErrorAdditionalData = [];
 
@@ -184,7 +184,8 @@ public function getErrorCode()
      * Sets the validation error type.
      *
      * @param string $validationErrorType
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      */
     public function setValidationErrorType($validationErrorType, array $additionalData = [])
     {
@@ -205,7 +206,7 @@ public function getValidationErrorType()
     /**
      * Returns the validation error additional data array.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getValidationErrorAdditionalData()
     {
@@ -215,7 +216,7 @@ public function getValidationErrorAdditionalData()
     /**
      * Returns the image data of the file or `null` if the file is no image.
      *
-     * @return  array|null
+     * @return array{width: int, height: int, mimeType: string}|null
      */
     public function getImageData()
     {
@@ -235,6 +236,7 @@ public function getImageData()
      * and the internal filename value to the new filename derived from the given location.
      *
      * @param string $newLocation new file location
+     * @return void
      */
     public function moveUploadedFile($newLocation)
     {
diff --git a/wcfsetup/install/files/lib/system/upload/UploadHandler.class.php b/wcfsetup/install/files/lib/system/upload/UploadHandler.class.php
index 8993b22af4f..f242555718b 100644
--- a/wcfsetup/install/files/lib/system/upload/UploadHandler.class.php
+++ b/wcfsetup/install/files/lib/system/upload/UploadHandler.class.php
@@ -21,7 +21,7 @@ class UploadHandler
 
     /**
      * list of validation errors.
-     * @var array
+     * @var UploadFile[]
      */
     protected $erroneousFiles = [];
 
@@ -123,6 +123,7 @@ public function getErroneousFiles()
      * Saves the uploaded files.
      *
      * @param IUploadFileSaveStrategy $saveStrategy
+     * @return void
      */
     public function saveFiles(IUploadFileSaveStrategy $saveStrategy)
     {
diff --git a/wcfsetup/install/files/lib/system/user/GroupedUserList.class.php b/wcfsetup/install/files/lib/system/user/GroupedUserList.class.php
index 48d141b6eef..b007d2ac28c 100644
--- a/wcfsetup/install/files/lib/system/user/GroupedUserList.class.php
+++ b/wcfsetup/install/files/lib/system/user/GroupedUserList.class.php
@@ -12,6 +12,7 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @implements \Iterator<UserProfile>
  */
 class GroupedUserList implements \Countable, \Iterator
 {
diff --git a/wcfsetup/install/files/lib/system/user/UserBirthdayCache.class.php b/wcfsetup/install/files/lib/system/user/UserBirthdayCache.class.php
index 009ef4ef2af..65cfc490a78 100644
--- a/wcfsetup/install/files/lib/system/user/UserBirthdayCache.class.php
+++ b/wcfsetup/install/files/lib/system/user/UserBirthdayCache.class.php
@@ -31,6 +31,7 @@ class UserBirthdayCache extends SingletonFactory
      * Loads the birthday cache.
      *
      * @param int $month
+     * @return void
      */
     protected function loadMonth($month)
     {
diff --git a/wcfsetup/install/files/lib/system/user/UserProfileHandler.class.php b/wcfsetup/install/files/lib/system/user/UserProfileHandler.class.php
index 17cd56d5eeb..6a7b6a225c0 100644
--- a/wcfsetup/install/files/lib/system/user/UserProfileHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/UserProfileHandler.class.php
@@ -37,7 +37,7 @@ protected function init()
      * Delegates method calls to the user profile object.
      *
      * @param string $name
-     * @param array $arguments
+     * @param mixed[] $arguments
      * @return  mixed
      */
     public function __call($name, $arguments)
@@ -59,6 +59,8 @@ public function __get($name)
 
     /**
      * Reloads the user profile object with data directly from the database.
+     *
+     * @return void
      */
     public function reloadUserProfile()
     {
diff --git a/wcfsetup/install/files/lib/system/user/activity/event/IUserActivityEvent.class.php b/wcfsetup/install/files/lib/system/user/activity/event/IUserActivityEvent.class.php
index 2bc68946479..75341a8fd1d 100644
--- a/wcfsetup/install/files/lib/system/user/activity/event/IUserActivityEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/activity/event/IUserActivityEvent.class.php
@@ -17,6 +17,7 @@ interface IUserActivityEvent
      * Prepares a list of events for output.
      *
      * @param ViewableUserActivityEvent[] $events
+     * @return void
      */
     public function prepare(array $events);
 }
diff --git a/wcfsetup/install/files/lib/system/user/activity/event/TCommentResponseUserActivityEvent.class.php b/wcfsetup/install/files/lib/system/user/activity/event/TCommentResponseUserActivityEvent.class.php
index 24d6642fd8c..4aeb542f2a3 100644
--- a/wcfsetup/install/files/lib/system/user/activity/event/TCommentResponseUserActivityEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/activity/event/TCommentResponseUserActivityEvent.class.php
@@ -51,6 +51,7 @@ trait TCommentResponseUserActivityEvent
      * Reads the data of the comment responses the given events belong to.
      *
      * @param ViewableUserActivityEvent[] $events
+     * @return void
      */
     protected function readResponseData(array $events)
     {
diff --git a/wcfsetup/install/files/lib/system/user/activity/event/UserActivityEventHandler.class.php b/wcfsetup/install/files/lib/system/user/activity/event/UserActivityEventHandler.class.php
index 49d7d0a4842..4842c9c5dbb 100644
--- a/wcfsetup/install/files/lib/system/user/activity/event/UserActivityEventHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/activity/event/UserActivityEventHandler.class.php
@@ -69,7 +69,7 @@ public function getObjectTypeID($objectType)
      * @param int $languageID
      * @param int $userID
      * @param int $time
-     * @param array $additionalData
+     * @param mixed[] $additionalData
      * @return  \wcf\data\user\activity\event\UserActivityEvent
      * @throws  SystemException
      */
@@ -111,7 +111,8 @@ public function fireEvent(
      * This method is intended for bulk processing.
      *
      * @param string $objectType
-     * @param array $eventData
+     * @param mixed[] $eventData
+     * @return void
      * @throws  SystemException
      */
     public function fireEvents($objectType, array $eventData)
@@ -155,6 +156,7 @@ public function fireEvents($objectType, array $eventData)
      * @param string $objectType
      * @param int $objectID
      * @param int $userID
+     * @return void
      * @throws  SystemException
      */
     public function removeEvent($objectType, $objectID, $userID = null)
@@ -185,6 +187,7 @@ public function removeEvent($objectType, $objectID, $userID = null)
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      * @throws  SystemException
      */
     public function removeEvents($objectType, array $objectIDs)
@@ -211,7 +214,7 @@ public function removeEvents($objectType, array $objectIDs)
     /**
      * Validates an event list and removes orphaned events.
      *
-     * @param ViewableUserActivityEventList $eventList
+     * @return void
      */
     public static function validateEvents(ViewableUserActivityEventList $eventList)
     {
diff --git a/wcfsetup/install/files/lib/system/user/activity/point/UserActivityPointHandler.class.php b/wcfsetup/install/files/lib/system/user/activity/point/UserActivityPointHandler.class.php
index a70c8229a88..b720ba3d688 100644
--- a/wcfsetup/install/files/lib/system/user/activity/point/UserActivityPointHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/activity/point/UserActivityPointHandler.class.php
@@ -52,6 +52,7 @@ protected function init()
      * @param int $objectID
      * @param int $userID
      * @param mixed[] $additionalData
+     * @return void
      * @throws  InvalidObjectTypeException
      * @throws  SystemException
      */
@@ -110,6 +111,7 @@ public function fireEvent($objectType, $objectID, $userID = null, array $additio
      * @param string $objectType
      * @param int[] $itemsToUser
      * @param bool $updateUsers
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function fireEvents($objectType, array $itemsToUser, $updateUsers = true)
@@ -165,6 +167,7 @@ public function fireEvents($objectType, array $itemsToUser, $updateUsers = true)
      *
      * @param string $objectType
      * @param int[] $userToItems
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function removeEvents($objectType, array $userToItems)
@@ -204,6 +207,7 @@ public function removeEvents($objectType, array $userToItems)
      * Updates total activity points and ranks for given user ids.
      *
      * @param int[] $userIDs
+     * @return void
      */
     public function updateUsers(array $userIDs)
     {
@@ -230,6 +234,7 @@ public function updateUsers(array $userIDs)
      * Resets activity points and items for a given object type.
      *
      * @param string $objectType
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function reset($objectType)
@@ -280,6 +285,7 @@ public function getObjectTypeByName($objectType)
      * Updates the user ranks for the given users.
      *
      * @param int[] $userIDs
+     * @return void
      */
     protected function updateUserRanks(array $userIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/user/authentication/DefaultUserAuthentication.class.php b/wcfsetup/install/files/lib/system/user/authentication/DefaultUserAuthentication.class.php
index f91b30fdd75..0e7c1a3a380 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/DefaultUserAuthentication.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/DefaultUserAuthentication.class.php
@@ -15,6 +15,7 @@
 class DefaultUserAuthentication extends AbstractUserAuthentication
 {
     /**
+     * @return false
      * @deprecated 5.4 - This method always returns false, as the legacy automated login was removed.
      */
     public function supportsPersistentLogins()
@@ -23,6 +24,9 @@ public function supportsPersistentLogins()
     }
 
     /**
+     * @param string $username
+     * @param string $password
+     * @return void
      * @deprecated 5.4 - This method is a noop, as user sessions are long-lived now.
      */
     public function storeAccessData(User $user, $username, $password)
@@ -55,6 +59,9 @@ public function loginManually(
     }
 
     /**
+     * @param bool $persistent
+     * @param string $userClassname
+     * @return void
      * @deprecated 5.4 - This method always returns null, as user sessions are long-lived now.
      */
     public function loginAutomatically($persistent = false, $userClassname = User::class)
@@ -73,6 +80,10 @@ protected function getUserByLogin($login)
     }
 
     /**
+     * @param int $userID
+     * @param string $password
+     * @param string $userClassname
+     * @return void
      * @deprecated 5.4 - This method always returns null, as user sessions are long-lived now.
      */
     protected function getUserAutomatically($userID, $password, $userClassname = User::class)
@@ -80,6 +91,9 @@ protected function getUserAutomatically($userID, $password, $userClassname = Use
     }
 
     /**
+     * @param string $user
+     * @param string $password
+     * @return false
      * @deprecated 5.4 - This method always returns false, as user sessions are long-lived now.
      */
     protected function checkCookiePassword($user, $password)
diff --git a/wcfsetup/install/files/lib/system/user/authentication/oauth/User.class.php b/wcfsetup/install/files/lib/system/user/authentication/oauth/User.class.php
index 916d13f981e..d1561222af8 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/oauth/User.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/oauth/User.class.php
@@ -9,11 +9,18 @@
  * @copyright   2001-2021 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.4
+ * @implements \ArrayAccess<string, string|array<string, string>>
  */
 final class User implements \ArrayAccess
 {
-    private $data = [];
+    /**
+     * @var array<string, string|array<string, string>>
+     */
+    private array $data = [];
 
+    /**
+     * @param array<string, string|array<string, string>> $data
+     */
     public function __construct(array $data)
     {
         if (empty($data['__id'])) {
diff --git a/wcfsetup/install/files/lib/system/user/authentication/oauth/exception/StateValidationException.class.php b/wcfsetup/install/files/lib/system/user/authentication/oauth/exception/StateValidationException.class.php
index 97c6dcd7f52..65f2ddbafa6 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/oauth/exception/StateValidationException.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/oauth/exception/StateValidationException.class.php
@@ -12,7 +12,7 @@
  */
 final class StateValidationException extends \UnexpectedValueException
 {
-    public function __construct($message, ?\Throwable $previous = null)
+    public function __construct(string $message, ?\Throwable $previous = null)
     {
         parent::__construct($message, 0, $previous);
     }
diff --git a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/Bcrypt.class.php b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/Bcrypt.class.php
index 0c7c48137bb..6f5789c1ad0 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/Bcrypt.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/Bcrypt.class.php
@@ -14,10 +14,7 @@
  */
 final class Bcrypt implements IPasswordAlgorithm
 {
-    /**
-     * @var int
-     */
-    private $cost;
+    private int $cost;
 
     /**
      * @param int $cost The BCrypt 'cost' option for newly created hashes. It is recommended not to change this option.
@@ -71,8 +68,10 @@ public function needsRehash(string $hash): bool
 
     /**
      * Returns the value to be used for password_*'s `$options` parameter.
+     *
+     * @return array{cost: int}
      */
-    private function getOptions()
+    private function getOptions(): array
     {
         return [
             'cost' => $this->cost,
diff --git a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/DoubleBcrypt.class.php b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/DoubleBcrypt.class.php
index 407263e05b2..31be718f4cd 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/DoubleBcrypt.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/DoubleBcrypt.class.php
@@ -15,7 +15,7 @@
  */
 final class DoubleBcrypt implements IPasswordAlgorithm
 {
-    private static $blowfishCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789./';
+    private static string $blowfishCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789./';
 
     /**
      * blowfish cost factor
@@ -68,16 +68,12 @@ public static function isLegacyDoubleBcrypt(string $hash): bool
 
     /**
      * Returns a double salted bcrypt hash.
-     *
-     * @param string $password
-     * @param string $salt
-     * @return  string
      */
     private static function getDoubleSaltedHash(
         #[\SensitiveParameter]
-        $password,
-        $salt = null
-    ) {
+        string $password,
+        ?string $salt = null
+    ): string {
         if ($salt === null) {
             $salt = self::getRandomSalt();
         }
@@ -87,16 +83,12 @@ private static function getDoubleSaltedHash(
 
     /**
      * Returns a simple salted bcrypt hash.
-     *
-     * @param string $password
-     * @param string $salt
-     * @return  string
      */
     private static function getSaltedHash(
         #[\SensitiveParameter]
-        $password,
-        $salt = null
-    ) {
+        string $password,
+        ?string $salt = null
+    ): string {
         if ($salt === null) {
             $salt = self::getRandomSalt();
         }
@@ -106,10 +98,8 @@ private static function getSaltedHash(
 
     /**
      * Returns a random blowfish-compatible salt.
-     *
-     * @return  string
      */
-    private static function getRandomSalt()
+    private static function getRandomSalt(): string
     {
         $salt = '';
 
@@ -122,11 +112,8 @@ private static function getRandomSalt()
 
     /**
      * Returns a blowfish salt, e.g. $2a$07$usesomesillystringforsalt$
-     *
-     * @param string $salt
-     * @return  string
      */
-    private static function getSalt($salt)
+    private static function getSalt(string $salt): string
     {
         $salt = \mb_substr($salt, 0, 22, '8bit');
 
@@ -135,11 +122,8 @@ private static function getSalt($salt)
 
     /**
      * Returns true if given bcrypt hash uses a different cost factor and should be re-computed.
-     *
-     * @param string $hash
-     * @return  bool
      */
-    private static function isDifferentBlowfish($hash)
+    private static function isDifferentBlowfish(string $hash): bool
     {
         $currentCost = \intval(self::BCRYPT_COST);
         $hashCost = \intval(\mb_substr($hash, 4, 2, '8bit'));
diff --git a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/TPhpass.class.php b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/TPhpass.class.php
index 1878caa6f39..0309db29fea 100644
--- a/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/TPhpass.class.php
+++ b/wcfsetup/install/files/lib/system/user/authentication/password/algorithm/TPhpass.class.php
@@ -14,7 +14,7 @@
  */
 trait TPhpass
 {
-    private $itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
+    private string $itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
 
     /**
      * Returns the hashed password, with the given settings.
diff --git a/wcfsetup/install/files/lib/system/user/collapsible/content/UserCollapsibleContentHandler.class.php b/wcfsetup/install/files/lib/system/user/collapsible/content/UserCollapsibleContentHandler.class.php
index 70bdf0c1edf..cc38435731b 100644
--- a/wcfsetup/install/files/lib/system/user/collapsible/content/UserCollapsibleContentHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/collapsible/content/UserCollapsibleContentHandler.class.php
@@ -223,6 +223,7 @@ public function markAsOpened(int $objectTypeID, string $objectID, ?int $userID =
      * Deletes all saved states for a specific object type.
      *
      * @param int $objectTypeID
+     * @return void
      */
     public function reset($objectTypeID)
     {
@@ -258,6 +259,7 @@ public function reset($objectTypeID)
      *
      * @param string $objectType
      * @param int $objectID
+     * @return void
      * @throws  InvalidObjectTypeException
      */
     public function resetAll($objectType, $objectID = null)
diff --git a/wcfsetup/install/files/lib/system/user/command/Follow.class.php b/wcfsetup/install/files/lib/system/user/command/Follow.class.php
index 7aecb2bbbf3..4e56a08dcd1 100644
--- a/wcfsetup/install/files/lib/system/user/command/Follow.class.php
+++ b/wcfsetup/install/files/lib/system/user/command/Follow.class.php
@@ -36,7 +36,6 @@ public function __invoke(): void
             return;
         }
 
-        \assert($follow instanceof UserFollow);
         $this->sendNotification($follow);
         $this->fireActivityEvent();
         $this->resetUserStorage();
diff --git a/wcfsetup/install/files/lib/system/user/command/SetAvatar.class.php b/wcfsetup/install/files/lib/system/user/command/SetAvatar.class.php
index b77ee30e6be..e4bbd648c4b 100644
--- a/wcfsetup/install/files/lib/system/user/command/SetAvatar.class.php
+++ b/wcfsetup/install/files/lib/system/user/command/SetAvatar.class.php
@@ -25,10 +25,9 @@ final class SetAvatar
     public function __construct(
         private readonly User $user,
         private readonly ?File $file = null
-    ) {
-    }
+    ) {}
 
-    public function __invoke()
+    public function __invoke(): void
     {
         if ($this->file === null && $this->user->avatarFileID !== null) {
             (new FileAction([$this->user->avatarFileID], 'delete'))->executeAction();
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/AbstractDatabaseUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/AbstractDatabaseUserContentProvider.class.php
index 10abed3bc05..6bfa658bc39 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/AbstractDatabaseUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/AbstractDatabaseUserContentProvider.class.php
@@ -3,6 +3,8 @@
 namespace wcf\system\user\content\provider;
 
 use wcf\data\AbstractDatabaseObjectAction;
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectEditor;
 use wcf\data\DatabaseObjectList;
 use wcf\data\user\User;
 use wcf\system\exception\ImplementationException;
@@ -14,6 +16,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @template T of DatabaseObjectList
+ * @implements IUserContentProvider<T>
  */
 abstract class AbstractDatabaseUserContentProvider implements IUserContentProvider
 {
@@ -59,7 +64,7 @@ public function getContentListForUser(User $user)
             throw new ImplementationException($className, DatabaseObjectList::class);
         }
 
-        /** @var DatabaseObjectList $databaseObjectList */
+        /** @var T $databaseObjectList */
         $databaseObjectList = new $className();
         $tableAlias = \call_user_func([static::getDatabaseObjectClass(), 'getDatabaseTableAlias']);
         $databaseObjectList->getConditionBuilder()->add($tableAlias . '.userID = ?', [$user->userID]);
@@ -78,7 +83,9 @@ public function deleteContent(array $objectIDs)
             throw new ImplementationException($className, AbstractDatabaseObjectAction::class);
         }
 
-        /** @var AbstractDatabaseObjectAction $objectAction */
+        /**
+         * @var AbstractDatabaseObjectAction<DatabaseObject, DatabaseObjectEditor<DatabaseObject>> $objectAction
+         */
         $objectAction = new $className($objectIDs, 'delete');
         $objectAction->executeAction();
     }
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/ArticleUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/ArticleUserContentProvider.class.php
index 1c739490bd8..f81ef219c33 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/ArticleUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/ArticleUserContentProvider.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\user\content\provider;
 
 use wcf\data\article\Article;
+use wcf\data\article\ArticleList;
 
 /**
  * User content provider for articles.
@@ -11,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @extends AbstractDatabaseUserContentProvider<ArticleList>
  */
 class ArticleUserContentProvider extends AbstractDatabaseUserContentProvider
 {
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/CommentResponseUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/CommentResponseUserContentProvider.class.php
index b73c2c809ce..92c5b72eedc 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/CommentResponseUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/CommentResponseUserContentProvider.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\user\content\provider;
 
 use wcf\data\comment\response\CommentResponse;
+use wcf\data\comment\response\CommentResponseList;
 
 /**
  * User content provider for comment responses.
@@ -11,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @extends AbstractDatabaseUserContentProvider<CommentResponseList>
  */
 class CommentResponseUserContentProvider extends AbstractDatabaseUserContentProvider
 {
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/CommentUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/CommentUserContentProvider.class.php
index a13ec6fa409..1438e62914d 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/CommentUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/CommentUserContentProvider.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\user\content\provider;
 
 use wcf\data\comment\Comment;
+use wcf\data\comment\CommentList;
 
 /**
  * User content provider for comments.
@@ -11,6 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @extends AbstractDatabaseUserContentProvider<CommentList>
  */
 class CommentUserContentProvider extends AbstractDatabaseUserContentProvider
 {
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/IUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/IUserContentProvider.class.php
index 85b7fcf07f8..a8c099ea994 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/IUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/IUserContentProvider.class.php
@@ -12,14 +12,15 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @template T of DatabaseObjectList
  */
 interface IUserContentProvider
 {
     /**
      * Returns a DatabaseObjectList with all user content objects.
      *
-     * @param User $user
-     * @return      DatabaseObjectList
+     * @return T
      */
     public function getContentListForUser(User $user);
 
@@ -27,6 +28,7 @@ public function getContentListForUser(User $user);
      * Delete the content for the given object ids.
      *
      * @param int[] $objectIDs
+     * @return void
      */
     public function deleteContent(array $objectIDs);
 }
diff --git a/wcfsetup/install/files/lib/system/user/content/provider/ReactionUserContentProvider.class.php b/wcfsetup/install/files/lib/system/user/content/provider/ReactionUserContentProvider.class.php
index dae186ba3cb..666456ffff7 100644
--- a/wcfsetup/install/files/lib/system/user/content/provider/ReactionUserContentProvider.class.php
+++ b/wcfsetup/install/files/lib/system/user/content/provider/ReactionUserContentProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\user\content\provider;
 
+use wcf\data\DatabaseObject;
 use wcf\data\like\Like;
 use wcf\data\like\LikeList;
 use wcf\data\like\object\AbstractLikeObject;
@@ -18,6 +19,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
+ *
+ * @extends AbstractDatabaseUserContentProvider<LikeList>
  */
 class ReactionUserContentProvider extends AbstractDatabaseUserContentProvider
 {
@@ -41,10 +44,10 @@ public function deleteContent(array $objectIDs)
         foreach ($likeList as $like) {
             $objectType = ObjectTypeCache::getInstance()->getObjectType($like->objectTypeID);
 
-            /** @var IObjectTypeProvider $processor */
+            /** @var IObjectTypeProvider<DatabaseObject> $processor */
             $processor = $objectType->getProcessor();
 
-            /** @var AbstractLikeObject $likeableObject */
+            /** @var AbstractLikeObject<LikeObject> $likeableObject */
             $likeableObject = $processor->getObjectByID($like->objectID);
             $likeableObject->setObjectType($objectType);
 
diff --git a/wcfsetup/install/files/lib/system/user/group/assignment/UserGroupAssignmentHandler.class.php b/wcfsetup/install/files/lib/system/user/group/assignment/UserGroupAssignmentHandler.class.php
index 724467a8708..affd2528056 100644
--- a/wcfsetup/install/files/lib/system/user/group/assignment/UserGroupAssignmentHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/group/assignment/UserGroupAssignmentHandler.class.php
@@ -34,6 +34,7 @@ class UserGroupAssignmentHandler extends SingletonFactory
      * on purpose to make sure the latest data of the users are fetched.
      *
      * @param int[] $userIDs
+     * @return void
      */
     public function checkUsers(array $userIDs)
     {
diff --git a/wcfsetup/install/files/lib/system/user/group/command/CopyUserGroup.class.php b/wcfsetup/install/files/lib/system/user/group/command/CopyUserGroup.class.php
index 3e73ecb5492..0ee849fcb77 100644
--- a/wcfsetup/install/files/lib/system/user/group/command/CopyUserGroup.class.php
+++ b/wcfsetup/install/files/lib/system/user/group/command/CopyUserGroup.class.php
@@ -26,7 +26,7 @@ public function __construct(
     ) {
     }
 
-    public function __invoke()
+    public function __invoke(): UserGroup
     {
         // fetch user group option values
         if ($this->copyUserGroupOptions) {
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/BackupMultifactorMethod.class.php b/wcfsetup/install/files/lib/system/user/multifactor/BackupMultifactorMethod.class.php
index 1c7eff7ae90..9a6c36b8a51 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/BackupMultifactorMethod.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/BackupMultifactorMethod.class.php
@@ -173,6 +173,8 @@ static function (ButtonFormField $field) {
 
     /**
      * Generates a list of codes.
+     *
+     * @return array<int, string>
      */
     private function generateCodes(): array
     {
@@ -199,6 +201,7 @@ private function generateCodes(): array
 
     /**
      * @inheritDoc
+     * @return array<int, string>
      */
     public function processManagementForm(IFormDocument $form, Setup $setup): array
     {
@@ -232,6 +235,9 @@ public function processManagementForm(IFormDocument $form, Setup $setup): array
     /**
      * Returns a code from $codes matching the $userCode. `null` is returned if
      * no matching code could be found.
+     *
+     * @param mixed[][] $codes
+     * @return mixed[]|null
      */
     private function findValidCode(string $userCode, array $codes): ?array
     {
@@ -348,6 +354,8 @@ public function processAuthenticationForm(IFormDocument $form, Setup $setup): vo
 
     /**
      * Notifies the user that an backup code has been used.
+     *
+     * @param mixed[] $usedCode
      */
     private function sendAuthenticationEmail(Setup $setup, array $usedCode): void
     {
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/EmailMultifactorMethod.class.php b/wcfsetup/install/files/lib/system/user/multifactor/EmailMultifactorMethod.class.php
index 81beaee932f..c6c0297cb6b 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/EmailMultifactorMethod.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/EmailMultifactorMethod.class.php
@@ -95,6 +95,9 @@ public function processManagementForm(IFormDocument $form, Setup $setup): void
     /**
      * Returns a code from $codes matching the $userCode. `null` is returned if
      * no matching code could be found.
+     *
+     * @param mixed[][] $codes
+     * @return mixed[]
      */
     private function findValidCode(string $userCode, array $codes): ?array
     {
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/IMultifactorMethod.class.php b/wcfsetup/install/files/lib/system/user/multifactor/IMultifactorMethod.class.php
index ed34acd680b..3d185c557c5 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/IMultifactorMethod.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/IMultifactorMethod.class.php
@@ -23,6 +23,8 @@ public function getStatusText(Setup $setup): string;
 
     /**
      * Populates the form to set-up and manage this method.
+     *
+     * @param ?mixed $returnData
      */
     public function createManagementForm(IFormDocument $form, ?Setup $setup, $returnData = null): void;
 
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/Setup.class.php b/wcfsetup/install/files/lib/system/user/multifactor/Setup.class.php
index 8859669ae22..f02df7fbad2 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/Setup.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/Setup.class.php
@@ -20,12 +20,15 @@
 final class Setup implements IIDObject
 {
     /**
-     * @var array
+     * @var mixed[]
      */
-    private $row;
+    private array $row;
 
-    private $isDeleted = false;
+    private bool $isDeleted = false;
 
+    /**
+     * @param mixed[] $row
+     */
     private function __construct(array $row)
     {
         $this->row = $row;
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/TotpMultifactorMethod.class.php b/wcfsetup/install/files/lib/system/user/multifactor/TotpMultifactorMethod.class.php
index 7540a6cb1e2..7daf2e1c3c8 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/TotpMultifactorMethod.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/TotpMultifactorMethod.class.php
@@ -140,6 +140,7 @@ public function createManagementForm(IFormDocument $form, ?Setup $setup, $return
                 } else {
                     $button = new class extends FormButton
                     {
+                        /** @var string */
                         protected $templateName = '__multifactorTotpDeviceNoDeleteButton';
                     };
                     $button->id('no-delete-' . $row['deviceID'])
@@ -155,6 +156,7 @@ public function createManagementForm(IFormDocument $form, ?Setup $setup, $return
 
     /**
      * @inheritDoc
+     * @return array{action: string, deviceName: string}
      */
     public function processManagementForm(IFormDocument $form, Setup $setup): array
     {
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/totp/CodeFormField.class.php b/wcfsetup/install/files/lib/system/user/multifactor/totp/CodeFormField.class.php
index b001aaab209..c146a956afc 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/totp/CodeFormField.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/totp/CodeFormField.class.php
@@ -56,6 +56,7 @@ public function minCounter(int $minCounter): static
 
     /**
      * @inheritDoc
+     * @return array{value: mixed, minCounter: number}
      */
     public function getSaveValue(): array
     {
diff --git a/wcfsetup/install/files/lib/system/user/multifactor/totp/DeviceNode.class.php b/wcfsetup/install/files/lib/system/user/multifactor/totp/DeviceNode.class.php
index 71ebf44cd15..2ccf62252c1 100644
--- a/wcfsetup/install/files/lib/system/user/multifactor/totp/DeviceNode.class.php
+++ b/wcfsetup/install/files/lib/system/user/multifactor/totp/DeviceNode.class.php
@@ -26,12 +26,13 @@ class DeviceNode implements IFormChildNode, IFormParentNode
     }
 
     /**
-     * @var ?array
+     * @var (string|int)[]|null
      */
     protected $data;
 
     /**
      * @inheritDoc
+     * @var string
      */
     protected $templateName = '__multifactorTotpDeviceNode';
 
@@ -53,6 +54,7 @@ public function getHtml(): string
     /**
      * Sets the device data.
      *
+     * @param (string|int)[] $device
      * @return $this
      */
     public function setData(array $device): static
diff --git a/wcfsetup/install/files/lib/system/user/notification/TestableUserNotificationEventHandler.class.php b/wcfsetup/install/files/lib/system/user/notification/TestableUserNotificationEventHandler.class.php
index 9d7148b273a..0fa93c6047f 100644
--- a/wcfsetup/install/files/lib/system/user/notification/TestableUserNotificationEventHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/TestableUserNotificationEventHandler.class.php
@@ -187,7 +187,7 @@ public function getRecipient(?Language $language = null)
      * @param UserProfile $author
      * @param int $timesTriggered
      * @param int $guestTimesTriggered
-     * @param array $additionalData
+     * @param mixed[] $additionalData
      * @return  UserNotification
      */
     protected function getUserNotification(
@@ -304,7 +304,7 @@ public function getUserNotificationEvents(UserNotificationEvent $userNotificatio
      * data within the same request. This is crucial as during testing, objects
      * are created and used within the same request.
      *
-     * @param ICacheBuilder $cacheBuilder
+     * @return void
      */
     public function resetCacheBuilder(ICacheBuilder $cacheBuilder)
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/UserNotificationHandler.class.php b/wcfsetup/install/files/lib/system/user/notification/UserNotificationHandler.class.php
index 86b26723da9..ea67829e387 100644
--- a/wcfsetup/install/files/lib/system/user/notification/UserNotificationHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/UserNotificationHandler.class.php
@@ -92,6 +92,7 @@ protected function init()
      * @param mixed[] $additionalData
      * @param int $baseObjectID
      * @param int $contentLanguageID
+     * @return void
      * @throws  SystemException
      */
     public function fireEvent(
@@ -416,7 +417,7 @@ public function getNotifications($limit = 5, $offset = 0, $showConfirmedNotifica
      * Returns a mixed list of notifications, containing leading unconfirmed notifications in their chronological
      * order regardless of the overall order of already confirmed items.
      *
-     * @return  array
+     * @return mixed[]
      */
     public function getMixedNotifications()
     {
@@ -747,6 +748,7 @@ public function getObjectTypeProcessor($objectType)
      * @param UserNotification $notification
      * @param User $user
      * @param IUserNotificationEvent $event
+     * @return void
      */
     public function sendInstantMailNotification(
         UserNotification $notification,
@@ -856,8 +858,8 @@ public function sendInstantMailNotification(
      * @param string $objectType
      * @param int[] $recipientIDs
      * @param int[] $objectIDs
+     * @return void
      * @deprecated
-     *
      */
     public function deleteNotifications($eventName, $objectType, array $recipientIDs, array $objectIDs = [])
     {
@@ -869,6 +871,7 @@ public function deleteNotifications($eventName, $objectType, array $recipientIDs
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      * @throws  SystemException
      */
     public function removeNotifications($objectType, array $objectIDs)
@@ -930,6 +933,7 @@ public function removeNotifications($objectType, array $objectIDs)
      * @param string $objectType
      * @param int[] $recipientIDs
      * @param int[] $objectIDs
+     * @return void
      * @throws  SystemException
      */
     public function markAsConfirmed($eventName, $objectType, array $recipientIDs, array $objectIDs = [])
@@ -985,6 +989,7 @@ public function markAsConfirmed($eventName, $objectType, array $recipientIDs, ar
      * Marks a single notification id as confirmed.
      *
      * @param int $notificationID
+     * @return void
      * @deprecated 5.2 Please use `UserNotificationHandler::markAsConfirmedByIDs()` instead.
      */
     public function markAsConfirmedByID($notificationID)
@@ -996,6 +1001,7 @@ public function markAsConfirmedByID($notificationID)
      * Marks a list of notification ids as confirmed.
      *
      * @param int[] $notificationIDs
+     * @return void
      */
     public function markAsConfirmedByIDs(array $notificationIDs)
     {
@@ -1031,7 +1037,7 @@ public function markAsConfirmedByIDs(array $notificationIDs)
      *
      * @param string $objectType
      * @param string $eventName
-     * @return  mixed
+     * @return int|false
      */
     public function getEventSetting($objectType, $eventName)
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/AbstractSharedUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/AbstractSharedUserNotificationEvent.class.php
index 1ea082da7c9..8555eb2d832 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/AbstractSharedUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/AbstractSharedUserNotificationEvent.class.php
@@ -32,6 +32,8 @@ public function setObject(
     /**
      * Provide specialized handlers with object ids, these ids will be collected and should be
      * read once the first time data is requested from the notification event.
+     *
+     * @return void
      */
     abstract protected function prepare();
 }
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/AbstractUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/AbstractUserNotificationEvent.class.php
index ee254d91d6a..d44df034b59 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/AbstractUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/AbstractUserNotificationEvent.class.php
@@ -20,8 +20,8 @@
  * @copyright   2001-2019 WoltLab GmbH, Oliver Kliebisch
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserNotificationEvent   getDecoratedObject()
  * @mixin   UserNotificationEvent
+ * @extends DatabaseObjectDecorator<UserNotificationEvent>
  */
 abstract class AbstractUserNotificationEvent extends DatabaseObjectDecorator implements
     IUserNotificationEvent,
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/ArticleLikeUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/ArticleLikeUserNotificationEvent.class.php
index c204fbdd4a8..3a8d563527e 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/ArticleLikeUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/ArticleLikeUserNotificationEvent.class.php
@@ -153,6 +153,7 @@ public function isVisible()
 
     /**
      * @inheritDoc
+     * @return LikeableArticle
      */
     protected static function createTestLikeObject(UserProfile $recipient, UserProfile $author)
     {
@@ -163,6 +164,7 @@ protected static function createTestLikeObject(UserProfile $recipient, UserProfi
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getTestLikeableObjectTypeName()
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/ITestableUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/ITestableUserNotificationEvent.class.php
index 70541c00a5a..0eea0c0c776 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/ITestableUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/ITestableUserNotificationEvent.class.php
@@ -34,6 +34,7 @@ public function getTestCaseDescription();
      * Sets the description of the covered test case.
      *
      * @param string $description
+     * @return void
      */
     public function setTestCaseDescription($description);
 
@@ -47,7 +48,7 @@ public static function canBeTriggeredByGuests();
      * The test data has to be the same data given when an actual event is fired.
      *
      * @param IUserNotificationObject $object
-     * @return  array
+     * @return mixed[]
      */
     public static function getTestAdditionalData(IUserNotificationObject $object);
 
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/IUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/IUserNotificationEvent.class.php
index 8ec29df982d..6f212b4ae14 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/IUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/IUserNotificationEvent.class.php
@@ -105,6 +105,7 @@ public function isVisible();
      * Sets a list of authors for stacked notifications.
      *
      * @param UserProfile[] $authors
+     * @return void
      */
     public function setAuthors(array $authors);
 
@@ -121,7 +122,8 @@ public function getEventHash();
      * @param UserNotification $notification
      * @param IUserNotificationObject $object
      * @param UserProfile $author
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      */
     public function setObject(
         UserNotification $notification,
@@ -134,6 +136,7 @@ public function setObject(
      * Sets the language for the event
      *
      * @param Language $language
+     * @return void
      */
     public function setLanguage(Language $language);
 
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentResponseUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentResponseUserNotificationEvent.class.php
index f80e501147f..af1f977be27 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentResponseUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentResponseUserNotificationEvent.class.php
@@ -207,6 +207,7 @@ public static function canBeTriggeredByGuests()
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentUserNotificationEvent.class.php
index 41cf6597a0f..31ae286a715 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/ModerationQueueCommentUserNotificationEvent.class.php
@@ -169,6 +169,7 @@ public static function canBeTriggeredByGuests()
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/PageCommentResponseUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/PageCommentResponseUserNotificationEvent.class.php
index 0f1e1216331..15d476c08e0 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/PageCommentResponseUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/PageCommentResponseUserNotificationEvent.class.php
@@ -134,6 +134,7 @@ protected function getObjectTitle(): string
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/PageCommentUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/PageCommentUserNotificationEvent.class.php
index 868faa35bf2..76d6f60a481 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/PageCommentUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/PageCommentUserNotificationEvent.class.php
@@ -105,6 +105,7 @@ protected function getObjectTitle(): string
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/TTestableArticleCommentUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/TTestableArticleCommentUserNotificationEvent.class.php
index f9d4493f849..cfa79c56ce6 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/TTestableArticleCommentUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/TTestableArticleCommentUserNotificationEvent.class.php
@@ -23,6 +23,7 @@ trait TTestableArticleCommentUserNotificationEvent
     use TTestableCategorizedUserNotificationEvent;
 
     /**
+     * @return array{objectID: int, objectTypeID: ?int}
      * @see TTestableCommentUserNotificationEvent::createTestComment()
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCategorizedUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCategorizedUserNotificationEvent.class.php
index 264e6c26852..5bbafe45f22 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCategorizedUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCategorizedUserNotificationEvent.class.php
@@ -23,7 +23,7 @@ trait TTestableCategorizedUserNotificationEvent
      * Returns a newly created test category of the given object type.
      *
      * @param string $objectTypeName
-     * @param array $additionalData
+     * @param mixed[] $additionalData
      * @return  Category
      */
     protected static function createTestCategory($objectTypeName, array $additionalData = [])
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentLikeUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentLikeUserNotificationEvent.class.php
index 427061032ba..c6589f6df4c 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentLikeUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentLikeUserNotificationEvent.class.php
@@ -26,6 +26,7 @@ trait TTestableCommentLikeUserNotificationEvent
 
     /**
      * @inheritDoc
+     * @return LikeableComment
      */
     protected static function createTestLikeObject(UserProfile $recipient, UserProfile $author)
     {
@@ -48,6 +49,7 @@ public static function getTestAdditionalData(IUserNotificationObject $object)
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getTestLikeableObjectTypeName()
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentResponseLikeUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentResponseLikeUserNotificationEvent.class.php
index 4653e74db45..422c414c3d7 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentResponseLikeUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/TTestableCommentResponseLikeUserNotificationEvent.class.php
@@ -26,6 +26,7 @@ trait TTestableCommentResponseLikeUserNotificationEvent
 
     /**
      * @inheritDoc
+     * @return LikeableCommentResponse
      */
     protected static function createTestLikeObject(UserProfile $recipient, UserProfile $author)
     {
@@ -49,6 +50,7 @@ public static function getTestAdditionalData(IUserNotificationObject $object)
 
     /**
      * @inheritDoc
+     * @return string
      */
     protected static function getTestLikeableObjectTypeName()
     {
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/TTestablePageUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/TTestablePageUserNotificationEvent.class.php
index f0ebf84b9e0..759317bd2e0 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/TTestablePageUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/TTestablePageUserNotificationEvent.class.php
@@ -64,7 +64,7 @@ public static function getTestPage()
         return $page;
     }
 
-    private static function resetPageCache()
+    private static function resetPageCache(): void
     {
         // reset cache builders
         TestableUserNotificationEventHandler::getInstance()->resetCacheBuilder(PageCacheBuilder::getInstance());
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentLikeUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentLikeUserNotificationEvent.class.php
index c1a59497e2d..235a2e340f8 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentLikeUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentLikeUserNotificationEvent.class.php
@@ -135,6 +135,7 @@ protected function getCommentID()
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseLikeUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseLikeUserNotificationEvent.class.php
index c79e4a9dd1f..63ef007cde0 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseLikeUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseLikeUserNotificationEvent.class.php
@@ -151,6 +151,7 @@ protected function getResponseID()
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseOwnerUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseOwnerUserNotificationEvent.class.php
index 4939d0d0c59..124f312e8ca 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseOwnerUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseOwnerUserNotificationEvent.class.php
@@ -132,6 +132,7 @@ protected function getObjectTitle(): string
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseUserNotificationEvent.class.php
index 36d8c2085bc..ff710e65874 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentResponseUserNotificationEvent.class.php
@@ -114,6 +114,7 @@ protected function getObjectTitle(): string
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentUserNotificationEvent.class.php b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentUserNotificationEvent.class.php
index b58d089753b..ac60f447318 100644
--- a/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentUserNotificationEvent.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/event/UserProfileCommentUserNotificationEvent.class.php
@@ -103,6 +103,7 @@ protected function getObjectTitle(): string
 
     /**
      * @inheritDoc
+     * @return array{objectID: int, objectTypeID: ?int}
      * @since   3.1
      */
     protected static function getTestCommentObjectData(UserProfile $recipient, UserProfile $author)
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/ArticleUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/ArticleUserNotificationObject.class.php
index 2f8cb3482d8..5c9bbdf0af1 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/ArticleUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/ArticleUserNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Article         getDecoratedObject()
  * @mixin   Article
+ * @extends DatabaseObjectDecorator<Article>
  */
 class ArticleUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/CommentResponseUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/CommentResponseUserNotificationObject.class.php
index 7dfcee4c2cd..221e9c8c839 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/CommentResponseUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/CommentResponseUserNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  CommentResponse     getDecoratedObject()
  * @mixin   CommentResponse
+ * @extends DatabaseObjectDecorator<CommentResponse>
  */
 class CommentResponseUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/CommentUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/CommentUserNotificationObject.class.php
index fda4097c5a5..54c1b1e54d8 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/CommentUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/CommentUserNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Comment     getDecoratedObject()
  * @mixin   Comment
+ * @extends DatabaseObjectDecorator<Comment>
  */
 class CommentUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/LikeUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/LikeUserNotificationObject.class.php
index 17167b4b2f3..b918730ca77 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/LikeUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/LikeUserNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  Like    getDecoratedObject()
  * @mixin   Like
+ * @extends DatabaseObjectDecorator<Like>
  */
 class LikeUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/ModerationQueueUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/ModerationQueueUserNotificationObject.class.php
index 20acef36cd6..9b79945823d 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/ModerationQueueUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/ModerationQueueUserNotificationObject.class.php
@@ -13,8 +13,8 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.1
  *
- * @method  ModerationQueue     getDecoratedObject()
  * @mixin   ModerationQueue
+ * @extends DatabaseObjectDecorator<ModerationQueue>
  */
 final class ModerationQueueUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/PaidSubscriptionUserUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/PaidSubscriptionUserUserNotificationObject.class.php
index 3b5aa440d01..8f1417490db 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/PaidSubscriptionUserUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/PaidSubscriptionUserUserNotificationObject.class.php
@@ -14,8 +14,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  PaidSubscriptionUser    getDecoratedObject()
  * @mixin   PaidSubscriptionUser
+ * @extends DatabaseObjectDecorator<PaidSubscriptionUser>
  */
 class PaidSubscriptionUserUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/UserFollowUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/UserFollowUserNotificationObject.class.php
index 57d5b408ea7..c0d1a7d2434 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/UserFollowUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/UserFollowUserNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserFollow  getDecoratedObject()
  * @mixin   UserFollow
+ * @extends DatabaseObjectDecorator<UserFollow>
  */
 class UserFollowUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/UserRegistrationUserNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/UserRegistrationUserNotificationObject.class.php
index f650cfb1b70..ade28139437 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/UserRegistrationUserNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/UserRegistrationUserNotificationObject.class.php
@@ -13,8 +13,8 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       5.2
  *
- * @method  User    getDecoratedObject()
  * @mixin   User
+ * @extends DatabaseObjectDecorator<User>
  */
 class UserRegistrationUserNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/UserTrophyNotificationObject.class.php b/wcfsetup/install/files/lib/system/user/notification/object/UserTrophyNotificationObject.class.php
index 093c326f061..3f2d167c9eb 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/UserTrophyNotificationObject.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/UserTrophyNotificationObject.class.php
@@ -12,8 +12,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserTrophy  getDecoratedObject()
  * @mixin   UserTrophy
+ * @extends DatabaseObjectDecorator<UserTrophy>
  */
 class UserTrophyNotificationObject extends DatabaseObjectDecorator implements IUserNotificationObject
 {
diff --git a/wcfsetup/install/files/lib/system/user/notification/object/type/AbstractUserNotificationObjectType.class.php b/wcfsetup/install/files/lib/system/user/notification/object/type/AbstractUserNotificationObjectType.class.php
index 4cf70aa059e..7b2674677b7 100644
--- a/wcfsetup/install/files/lib/system/user/notification/object/type/AbstractUserNotificationObjectType.class.php
+++ b/wcfsetup/install/files/lib/system/user/notification/object/type/AbstractUserNotificationObjectType.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\user\notification\object\type;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\AbstractObjectTypeProcessor;
 
@@ -39,7 +40,7 @@ public function getObjectsByIDs(array $objectIDs)
     {
         $indexName = \call_user_func([static::$objectClassName, 'getDatabaseTableIndexName']);
 
-        /** @var DatabaseObjectList $objectList */
+        /** @var DatabaseObjectList<DatabaseObject> $objectList */
         $objectList = new static::$objectListClassName();
         $objectList->setObjectIDs($objectIDs);
         $objectList->sqlLimit = 0;
diff --git a/wcfsetup/install/files/lib/system/user/object/watch/IUserObjectWatch.class.php b/wcfsetup/install/files/lib/system/user/object/watch/IUserObjectWatch.class.php
index 8453c418d47..8330378237c 100644
--- a/wcfsetup/install/files/lib/system/user/object/watch/IUserObjectWatch.class.php
+++ b/wcfsetup/install/files/lib/system/user/object/watch/IUserObjectWatch.class.php
@@ -15,6 +15,7 @@ interface IUserObjectWatch
      * Validates the given object id. Throws an exception on error.
      *
      * @param int $objectID
+     * @return void
      * @throws  \wcf\system\exception\UserException
      */
     public function validateObjectID($objectID);
@@ -23,6 +24,7 @@ public function validateObjectID($objectID);
      * Resets the user storage for given users.
      *
      * @param int[] $userIDs
+     * @return void
      */
     public function resetUserStorage(array $userIDs);
 }
diff --git a/wcfsetup/install/files/lib/system/user/object/watch/UserObjectWatchHandler.class.php b/wcfsetup/install/files/lib/system/user/object/watch/UserObjectWatchHandler.class.php
index 54f07b7a8dc..5bbe3f7a186 100644
--- a/wcfsetup/install/files/lib/system/user/object/watch/UserObjectWatchHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/object/watch/UserObjectWatchHandler.class.php
@@ -38,7 +38,9 @@ public function getObjectTypeID($objectTypeName)
     }
 
     /**
-     * @inheritDoc
+     * @param string $objectType
+     * @param int $objectID
+     * @return void
      */
     public function resetObject($objectType, $objectID)
     {
@@ -50,6 +52,7 @@ public function resetObject($objectType, $objectID)
      *
      * @param string $objectType
      * @param int[] $objectIDs
+     * @return void
      */
     public function resetObjects($objectType, array $objectIDs)
     {
@@ -80,6 +83,7 @@ public function resetObjects($objectType, array $objectIDs)
      * @param string $objectType
      * @param int[] $objectIDs
      * @param int[] $userIDs
+     * @return void
      */
     public function deleteObjects($objectType, array $objectIDs, array $userIDs = [])
     {
@@ -109,7 +113,8 @@ public function deleteObjects($objectType, array $objectIDs, array $userIDs = []
      * @param string $notificationEventName
      * @param string $notificationObjectType
      * @param IUserNotificationObject $notificationObject
-     * @param array $additionalData
+     * @param mixed[] $additionalData
+     * @return void
      */
     public function updateObject(
         $objectType,
@@ -154,6 +159,7 @@ static function ($notification, $userID) use ($notificationObject) {
      * the notification status (`1` = should get a notification,
      * `0` = should not get a notification).
      *
+     * @return array<int, 0|1>
      * @since 5.5
      */
     public function getSubscribers(string $objectType, int $objectID): array
@@ -168,6 +174,7 @@ public function getSubscribers(string $objectType, int $objectID): array
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$objectTypeObj->objectTypeID, $objectID]);
 
+        // @phpstan-ignore return.type
         return $statement->fetchMap('userID', 'notification');
     }
 
@@ -175,6 +182,8 @@ public function getSubscribers(string $objectType, int $objectID): array
      * Updates a watched object for all subscribers including subscribers
      * of the parent object.
      *
+     * @param mixed[] $additionalData
+     * @return void
      * @since 5.5
      */
     public function updateObjectWithParent(
diff --git a/wcfsetup/install/files/lib/system/user/online/location/IUserOnlineLocation.class.php b/wcfsetup/install/files/lib/system/user/online/location/IUserOnlineLocation.class.php
index 93e77de2b36..fc8d146d91f 100644
--- a/wcfsetup/install/files/lib/system/user/online/location/IUserOnlineLocation.class.php
+++ b/wcfsetup/install/files/lib/system/user/online/location/IUserOnlineLocation.class.php
@@ -18,6 +18,7 @@ interface IUserOnlineLocation
      * Caches the information of a page location.
      *
      * @param UserOnline $user
+     * @return void
      */
     public function cache(UserOnline $user);
 
diff --git a/wcfsetup/install/files/lib/system/user/signature/SignatureCache.class.php b/wcfsetup/install/files/lib/system/user/signature/SignatureCache.class.php
index c77ae7e83ae..dbcac13398d 100644
--- a/wcfsetup/install/files/lib/system/user/signature/SignatureCache.class.php
+++ b/wcfsetup/install/files/lib/system/user/signature/SignatureCache.class.php
@@ -61,6 +61,7 @@ public function getSignature(User $user)
      * Loads the embedded objects for the given users.
      *
      * @param int[] $userIDs
+     * @return void
      * @since       5.2
      */
     public function cacheUserSignature(array $userIDs)
diff --git a/wcfsetup/install/files/lib/system/user/storage/UserStorageHandler.class.php b/wcfsetup/install/files/lib/system/user/storage/UserStorageHandler.class.php
index 242aea1bf60..f2eec49b8e8 100644
--- a/wcfsetup/install/files/lib/system/user/storage/UserStorageHandler.class.php
+++ b/wcfsetup/install/files/lib/system/user/storage/UserStorageHandler.class.php
@@ -29,11 +29,7 @@ final class UserStorageHandler extends SingletonFactory
      */
     private $log = [];
 
-    /**
-     * redis instance
-     * @var ?Redis
-     */
-    private $redis;
+    private ?Redis $redis = null;
 
     /**
      * Checks whether Redis is available.
@@ -51,7 +47,7 @@ protected function init()
      *
      * @param int[] $userIDs
      */
-    public function loadStorage(array $userIDs)
+    public function loadStorage(array $userIDs): void
     {
         $this->validateUserIDs($userIDs);
 
@@ -175,7 +171,7 @@ public function getField(string $field, ?int $userID = null)
     /**
      * Inserts new data records into database.
      */
-    public function update(int $userID, string $field, string $fieldValue)
+    public function update(int $userID, string $field, string $fieldValue): void
     {
         $this->validateUserIDs([$userID]);
 
@@ -202,7 +198,7 @@ public function update(int $userID, string $field, string $fieldValue)
      *
      * @param int[] $userIDs
      */
-    public function reset(array $userIDs, string $field)
+    public function reset(array $userIDs, string $field): void
     {
         $this->validateUserIDs($userIDs);
 
@@ -227,7 +223,7 @@ public function reset(array $userIDs, string $field)
     /**
      * Removes a specific data record for all users.
      */
-    public function resetAll(string $field)
+    public function resetAll(string $field): void
     {
         if ($this->redis) {
             $this->redis->del($this->getRedisFieldName($field));
@@ -336,7 +332,7 @@ public function shutdown()
     /**
      * Removes the entire user storage data.
      */
-    public function clear()
+    public function clear(): void
     {
         if ($this->redis) {
             $this->redis->setnx('ush:_flush', TIME_NOW);
@@ -376,7 +372,7 @@ private function getRedisFieldName(string $fieldName): string
      * @param int[] $userIDs
      * @since 5.2
      */
-    private function validateUserIDs(array $userIDs)
+    private function validateUserIDs(array $userIDs): void
     {
         foreach ($userIDs as $userID) {
             if (!$userID) {
diff --git a/wcfsetup/install/files/lib/system/version/AbstractVersionTrackerProvider.class.php b/wcfsetup/install/files/lib/system/version/AbstractVersionTrackerProvider.class.php
index f483ec898e9..4e9f239623f 100644
--- a/wcfsetup/install/files/lib/system/version/AbstractVersionTrackerProvider.class.php
+++ b/wcfsetup/install/files/lib/system/version/AbstractVersionTrackerProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\version;
 
+use wcf\data\DatabaseObject;
 use wcf\data\IVersionTrackerObject;
 use wcf\data\object\type\AbstractObjectTypeProvider;
 use wcf\system\WCF;
@@ -13,6 +14,10 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends AbstractObjectTypeProvider<TDatabaseObject>
+ * @implements IVersionTrackerProvider<TDatabaseObject>
  */
 abstract class AbstractVersionTrackerProvider extends AbstractObjectTypeProvider implements IVersionTrackerProvider
 {
diff --git a/wcfsetup/install/files/lib/system/version/ArticleVersionTrackerProvider.class.php b/wcfsetup/install/files/lib/system/version/ArticleVersionTrackerProvider.class.php
index 95cd972aa43..3c6cbbb381c 100644
--- a/wcfsetup/install/files/lib/system/version/ArticleVersionTrackerProvider.class.php
+++ b/wcfsetup/install/files/lib/system/version/ArticleVersionTrackerProvider.class.php
@@ -15,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractVersionTrackerProvider<Article>
  */
 class ArticleVersionTrackerProvider extends AbstractVersionTrackerProvider
 {
diff --git a/wcfsetup/install/files/lib/system/version/BoxVersionTrackerProvider.class.php b/wcfsetup/install/files/lib/system/version/BoxVersionTrackerProvider.class.php
index f3948c55531..f1bf0c73d46 100644
--- a/wcfsetup/install/files/lib/system/version/BoxVersionTrackerProvider.class.php
+++ b/wcfsetup/install/files/lib/system/version/BoxVersionTrackerProvider.class.php
@@ -15,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractVersionTrackerProvider<Box>
  */
 class BoxVersionTrackerProvider extends AbstractVersionTrackerProvider
 {
diff --git a/wcfsetup/install/files/lib/system/version/IVersionTrackerProvider.class.php b/wcfsetup/install/files/lib/system/version/IVersionTrackerProvider.class.php
index d0fa0400f12..c228ddb5d45 100644
--- a/wcfsetup/install/files/lib/system/version/IVersionTrackerProvider.class.php
+++ b/wcfsetup/install/files/lib/system/version/IVersionTrackerProvider.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\version;
 
+use wcf\data\DatabaseObject;
 use wcf\data\IVersionTrackerObject;
 use wcf\data\object\type\IObjectTypeProvider;
 
@@ -12,6 +13,9 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @template TDatabaseObject of DatabaseObject
+ * @extends IObjectTypeProvider<TDatabaseObject>
  */
 interface IVersionTrackerProvider extends IObjectTypeProvider
 {
@@ -82,6 +86,7 @@ public function isI18n(IVersionTrackerObject $object);
      *
      * @param IVersionTrackerObject $object target object
      * @param VersionTrackerEntry $entry previous version
+     * @return void
      */
     public function revert(IVersionTrackerObject $object, VersionTrackerEntry $entry);
 }
diff --git a/wcfsetup/install/files/lib/system/version/PageVersionTrackerProvider.class.php b/wcfsetup/install/files/lib/system/version/PageVersionTrackerProvider.class.php
index b4b3b83b92a..7e99cc44173 100644
--- a/wcfsetup/install/files/lib/system/version/PageVersionTrackerProvider.class.php
+++ b/wcfsetup/install/files/lib/system/version/PageVersionTrackerProvider.class.php
@@ -15,6 +15,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @extends AbstractVersionTrackerProvider<Page>
  */
 class PageVersionTrackerProvider extends AbstractVersionTrackerProvider
 {
diff --git a/wcfsetup/install/files/lib/system/version/VersionTracker.class.php b/wcfsetup/install/files/lib/system/version/VersionTracker.class.php
index a80f79299d7..e2505211d93 100644
--- a/wcfsetup/install/files/lib/system/version/VersionTracker.class.php
+++ b/wcfsetup/install/files/lib/system/version/VersionTracker.class.php
@@ -41,13 +41,13 @@ protected function init()
      * Adds a new entry to the version history.
      *
      * @param string $objectTypeName object type name
-     * @param IVersionTrackerObject $object target object
+     * @return void
      */
     public function add($objectTypeName, IVersionTrackerObject $object)
     {
         $objectType = $this->getObjectType($objectTypeName);
 
-        /** @var IVersionTrackerProvider $processor */
+        /** @var IVersionTrackerProvider<DatabaseObject> $processor */
         $processor = $objectType->getProcessor();
         $data = $processor->getTrackedData($object);
 
@@ -160,6 +160,8 @@ public function getVersion($objectTypeName, $versionID)
 
     /**
      * Creates the database tables to store each version.
+     *
+     * @return void
      */
     public function createStorageTables()
     {
@@ -205,6 +207,7 @@ public function getObjectType($name)
      *
      * @param string $objectTypeName object type name
      * @param int $objectID object id
+     * @return void
      */
     public function reset($objectTypeName, $objectID)
     {
diff --git a/wcfsetup/install/files/lib/system/version/VersionTrackerEntry.class.php b/wcfsetup/install/files/lib/system/version/VersionTrackerEntry.class.php
index 28e84ce090e..d54f13c1fc2 100644
--- a/wcfsetup/install/files/lib/system/version/VersionTrackerEntry.class.php
+++ b/wcfsetup/install/files/lib/system/version/VersionTrackerEntry.class.php
@@ -20,13 +20,13 @@ class VersionTrackerEntry
 {
     /**
      * object data
-     * @var array
+     * @var mixed[]
      */
     protected $data = [];
 
     /**
      * list of stored properties and their values
-     * @var array
+     * @var mixed[]
      */
     protected $payload = [];
 
@@ -34,7 +34,7 @@ class VersionTrackerEntry
      * VersionTrackerEntry constructor.
      *
      * @param ?int $id id
-     * @param array $data version data
+     * @param mixed[] $data version data
      */
     public function __construct($id, array $data)
     {
diff --git a/wcfsetup/install/files/lib/system/view/CommentsView.class.php b/wcfsetup/install/files/lib/system/view/CommentsView.class.php
index 281f80e64f0..56efa590df5 100644
--- a/wcfsetup/install/files/lib/system/view/CommentsView.class.php
+++ b/wcfsetup/install/files/lib/system/view/CommentsView.class.php
@@ -3,6 +3,7 @@
 namespace wcf\system\view;
 
 use wcf\data\comment\StructuredCommentList;
+use wcf\data\like\object\LikeObject;
 use wcf\system\comment\CommentHandler;
 use wcf\system\comment\manager\ICommentManager;
 use wcf\system\exception\SystemException;
@@ -64,11 +65,15 @@ public function getCommentList(): StructuredCommentList
         return $this->commentList;
     }
 
+
     public function getLastCommentTime(): int
     {
         return $this->commentList->getMinCommentTime();
     }
 
+    /**
+     * @return array{}|array{comment: LikeObject[], response?: LikeObject[]}
+     */
     public function getLikeData(): array
     {
         if (!MODULE_LIKE) {
diff --git a/wcfsetup/install/files/lib/system/visitTracker/VisitTracker.class.php b/wcfsetup/install/files/lib/system/visitTracker/VisitTracker.class.php
index 1af07a7366c..08cc1fefb3b 100644
--- a/wcfsetup/install/files/lib/system/visitTracker/VisitTracker.class.php
+++ b/wcfsetup/install/files/lib/system/visitTracker/VisitTracker.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\visitTracker;
 
+use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\exception\SystemException;
 use wcf\system\SingletonFactory;
@@ -30,13 +31,13 @@ class VisitTracker extends SingletonFactory
 
     /**
      * list of available object types
-     * @var array
+     * @var array<string, ObjectType>
      */
     protected $availableObjectTypes = [];
 
     /**
      * user visits
-     * @var array
+     * @var ?array<int, int>
      */
     protected $userVisits;
 
@@ -147,6 +148,7 @@ public function getObjectVisitTime($objectType, $objectID)
      * Deletes all tracked visits of a specific object type.
      *
      * @param string $objectType
+     * @return void
      */
     public function deleteObjectVisits($objectType)
     {
@@ -166,6 +168,7 @@ public function deleteObjectVisits($objectType)
      * @param int $objectID
      * @param int[] $userIDs
      * @param int $time
+     * @return void
      */
     public function trackObjectVisitByUserIDs($objectType, $objectID, array $userIDs, $time = TIME_NOW)
     {
@@ -190,6 +193,7 @@ public function trackObjectVisitByUserIDs($objectType, $objectID, array $userIDs
      * @param string $objectType
      * @param int $objectID
      * @param int $time
+     * @return void
      */
     public function trackObjectVisit($objectType, $objectID, $time = TIME_NOW)
     {
@@ -209,6 +213,7 @@ public function trackObjectVisit($objectType, $objectID, $time = TIME_NOW)
      *
      * @param string $objectType
      * @param int $time
+     * @return void
      */
     public function trackTypeVisit($objectType, $time = TIME_NOW)
     {
diff --git a/wcfsetup/install/files/lib/system/worker/AbstractLinearRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/AbstractLinearRebuildDataWorker.class.php
index 3de4344c31c..64884601166 100644
--- a/wcfsetup/install/files/lib/system/worker/AbstractLinearRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/AbstractLinearRebuildDataWorker.class.php
@@ -23,6 +23,9 @@
  * @copyright 2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
+ *
+ * @template T of DatabaseObjectList
+ * @extends AbstractRebuildDataWorker<T>
  */
 abstract class AbstractLinearRebuildDataWorker extends AbstractRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/AbstractRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/AbstractRebuildDataWorker.class.php
index a152fa6a4ab..d23e17ff269 100644
--- a/wcfsetup/install/files/lib/system/worker/AbstractRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/AbstractRebuildDataWorker.class.php
@@ -20,6 +20,9 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
+ * @implements IRebuildDataWorker<T>
  */
 abstract class AbstractRebuildDataWorker extends AbstractWorker implements IRebuildDataWorker
 {
@@ -31,7 +34,7 @@ abstract class AbstractRebuildDataWorker extends AbstractWorker implements IRebu
 
     /**
      * database object list
-     * @var DatabaseObjectList
+     * @var T
      */
     protected $objectList;
 
@@ -97,6 +100,8 @@ public function getProceedURL()
 
     /**
      * Initializes DatabaseObjectList instance.
+     *
+     * @return void
      */
     protected function initObjectList()
     {
@@ -119,7 +124,7 @@ protected function initObjectList()
      *
      * @param int[] $userIDs
      * @param string[] $permissions
-     * @return      mixed[]         permission value per user id
+     * @return mixed[] permission value per user id
      */
     protected function getBulkUserPermissions(array $userIDs, array $permissions)
     {
@@ -171,7 +176,7 @@ protected function getBulkUserPermissions(array $userIDs, array $permissions)
      * @param mixed[] $userPermissions
      * @param int $userID
      * @param string $permission
-     * @return      mixed
+     * @return mixed
      */
     protected function getBulkUserPermissionValue(array &$userPermissions, $userID, $permission)
     {
diff --git a/wcfsetup/install/files/lib/system/worker/AbstractWorker.class.php b/wcfsetup/install/files/lib/system/worker/AbstractWorker.class.php
index 471d1b7019c..1f9f5383d55 100644
--- a/wcfsetup/install/files/lib/system/worker/AbstractWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/AbstractWorker.class.php
@@ -31,7 +31,7 @@ abstract class AbstractWorker implements IWorker
 
     /**
      * list of additional parameters
-     * @var array
+     * @var mixed[]
      */
     protected $parameters = [];
 
@@ -53,6 +53,8 @@ public function setLoopCount($loopCount)
 
     /**
      * Counts objects applicable for worker action.
+     *
+     * @return void
      */
     abstract protected function countObjects();
 
diff --git a/wcfsetup/install/files/lib/system/worker/ArticleRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/ArticleRebuildDataWorker.class.php
index 96accb43221..3b129698817 100644
--- a/wcfsetup/install/files/lib/system/worker/ArticleRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/ArticleRebuildDataWorker.class.php
@@ -22,7 +22,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.0
  *
- * @method  ArticleList getObjectList()
+ * @extends AbstractRebuildDataWorker<ArticleList>
  */
 class ArticleRebuildDataWorker extends AbstractRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/AttachmentRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/AttachmentRebuildDataWorker.class.php
index 6a57ce3569d..15352686ee0 100644
--- a/wcfsetup/install/files/lib/system/worker/AttachmentRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/AttachmentRebuildDataWorker.class.php
@@ -15,7 +15,7 @@
  * @copyright 2001-2024 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  AttachmentList  getObjectList()
+ * @extends AbstractLinearRebuildDataWorker<AttachmentList>
  * @deprecated 6.1 Should be removed in 6.2 as its only purpose is to migrate to the new upload API.
  */
 class AttachmentRebuildDataWorker extends AbstractLinearRebuildDataWorker
@@ -42,8 +42,6 @@ public function execute()
         $defunctAttachmentIDs = [];
 
         foreach ($this->objectList as $attachment) {
-            \assert($attachment instanceof Attachment);
-
             if ($attachment->fileID !== null) {
                 $this->removeThumbnails($attachment);
 
diff --git a/wcfsetup/install/files/lib/system/worker/BulkProcessingWorker.class.php b/wcfsetup/install/files/lib/system/worker/BulkProcessingWorker.class.php
index 0f4f71a267d..31cbf40b8ce 100644
--- a/wcfsetup/install/files/lib/system/worker/BulkProcessingWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/BulkProcessingWorker.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\worker;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\system\bulk\processing\IBulkProcessingAction;
 use wcf\system\exception\PermissionDeniedException;
@@ -20,7 +22,15 @@ final class BulkProcessingWorker extends AbstractWorker
      * @inheritDoc
      */
     protected $limit = 100;
+
+    /**
+     * @var array<string, mixed>
+     */
     protected array $bulkProcessingData;
+
+    /**
+     * @var IBulkProcessingAction<DatabaseObjectList<DatabaseObject>>
+     */
     protected IBulkProcessingAction $action;
 
     #[\Override]
diff --git a/wcfsetup/install/files/lib/system/worker/CommentRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/CommentRebuildDataWorker.class.php
index 74e1028e4a3..e4fc029e4e1 100644
--- a/wcfsetup/install/files/lib/system/worker/CommentRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/CommentRebuildDataWorker.class.php
@@ -16,6 +16,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends AbstractLinearRebuildDataWorker<CommentList>
  */
 final class CommentRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/CommentResponseRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/CommentResponseRebuildDataWorker.class.php
index 3106f97d47e..49f73100b19 100644
--- a/wcfsetup/install/files/lib/system/worker/CommentResponseRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/CommentResponseRebuildDataWorker.class.php
@@ -16,6 +16,8 @@
  * @author  Alexander Ebert
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @extends AbstractLinearRebuildDataWorker<CommentResponseList>
  */
 final class CommentResponseRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/FileRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/FileRebuildDataWorker.class.php
index aa03b53b40b..c5de6db0bb7 100644
--- a/wcfsetup/install/files/lib/system/worker/FileRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/FileRebuildDataWorker.class.php
@@ -17,8 +17,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since 6.1
  *
- * @method FileList getObjectList()
- * @property-read FileList $objectList
+ * @extends AbstractLinearRebuildDataWorker<FileList>
  */
 final class FileRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/IRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/IRebuildDataWorker.class.php
index 6544d537808..72992b569fc 100644
--- a/wcfsetup/install/files/lib/system/worker/IRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/IRebuildDataWorker.class.php
@@ -10,13 +10,15 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @template T of DatabaseObjectList
  */
 interface IRebuildDataWorker extends IWorker
 {
     /**
      * Returns the list of objects.
      *
-     * @return DatabaseObjectList|null
+     * @return ?T
      */
     public function getObjectList();
 }
diff --git a/wcfsetup/install/files/lib/system/worker/IWorker.class.php b/wcfsetup/install/files/lib/system/worker/IWorker.class.php
index 67b8d150ec4..039fb49c4a8 100644
--- a/wcfsetup/install/files/lib/system/worker/IWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/IWorker.class.php
@@ -14,7 +14,7 @@ interface IWorker
     /**
      * Creates a new worker object with additional parameters
      *
-     * @param array $parameters
+     * @param mixed[] $parameters
      */
     public function __construct(array $parameters);
 
@@ -22,6 +22,7 @@ public function __construct(array $parameters);
      * Sets current loop count.
      *
      * @param int $loopCount
+     * @return void
      */
     public function setLoopCount($loopCount);
 
@@ -35,18 +36,22 @@ public function getProgress();
 
     /**
      * Executes worker action.
+     *
+     * @return void
      */
     public function execute();
 
     /**
      * Returns parameters previously given within __construct().
      *
-     * @return  array
+     * @return  mixed[]
      */
     public function getParameters();
 
     /**
      * Validates parameters.
+     *
+     * @return void
      */
     public function validate();
 
diff --git a/wcfsetup/install/files/lib/system/worker/ImportWorker.class.php b/wcfsetup/install/files/lib/system/worker/ImportWorker.class.php
index 56d8c512879..42dc5ff59fb 100644
--- a/wcfsetup/install/files/lib/system/worker/ImportWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/ImportWorker.class.php
@@ -19,7 +19,7 @@ class ImportWorker extends AbstractWorker
 {
     /**
      * import data
-     * @var array
+     * @var array<string, string|int>
      */
     protected $importData;
 
diff --git a/wcfsetup/install/files/lib/system/worker/LikeRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/LikeRebuildDataWorker.class.php
index 6a3874b98ad..cf26bd8def8 100644
--- a/wcfsetup/install/files/lib/system/worker/LikeRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/LikeRebuildDataWorker.class.php
@@ -14,7 +14,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  LikeList    getObjectList()
+ * @extends AbstractLinearRebuildDataWorker<LikeList>
  */
 final class LikeRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
@@ -178,7 +178,7 @@ public function execute()
      *
      * @param int[]|null $oldCachedReactions
      * @param int[] $newCachedReactions
-     * @return      int[]
+     * @return int[]
      */
     private function mergeCachedReactions($oldCachedReactions, array $newCachedReactions)
     {
diff --git a/wcfsetup/install/files/lib/system/worker/MailWorker.class.php b/wcfsetup/install/files/lib/system/worker/MailWorker.class.php
index ceaa4ee49eb..0c28d864a00 100644
--- a/wcfsetup/install/files/lib/system/worker/MailWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/MailWorker.class.php
@@ -37,7 +37,7 @@ class MailWorker extends AbstractWorker
 
     /**
      * mail data
-     * @var array
+     * @var array{action: string, enableHTML: 1|0, from: string, fromName?: string, groupIDs: int[], 'message-id': string, subject: string, text: string, userIDs: int[]}
      */
     protected $mailData;
 
@@ -173,6 +173,7 @@ public function execute()
      *
      * @param Email $blueprint
      * @param User $user
+     * @return void
      */
     protected function sendMail(Email $blueprint, User $user)
     {
diff --git a/wcfsetup/install/files/lib/system/worker/MediaRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/MediaRebuildDataWorker.class.php
index be741914618..f95f2e63586 100644
--- a/wcfsetup/install/files/lib/system/worker/MediaRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/MediaRebuildDataWorker.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  MediaList   getObjectList()
+ * @extends AbstractRebuildDataWorker<MediaList>
  */
 class MediaRebuildDataWorker extends AbstractRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/PageRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/PageRebuildDataWorker.class.php
index 965d8bb0038..ad70ac6e612 100644
--- a/wcfsetup/install/files/lib/system/worker/PageRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/PageRebuildDataWorker.class.php
@@ -19,7 +19,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
  *
- * @method  PageList    getObjectList()
+ * @extends AbstractRebuildDataWorker<PageList>
  */
 class PageRebuildDataWorker extends AbstractRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/PollRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/PollRebuildDataWorker.class.php
index b9fc4f91c87..d50332797cd 100644
--- a/wcfsetup/install/files/lib/system/worker/PollRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/PollRebuildDataWorker.class.php
@@ -13,7 +13,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  PollList    getObjectList()
+ * @extends AbstractRebuildDataWorker<PollList>
  */
 class PollRebuildDataWorker extends AbstractRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php b/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
index a9dbd3f9954..a5bba896989 100644
--- a/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/SendNewPasswordWorker.class.php
@@ -39,7 +39,7 @@ public function countObjects()
         $userList = new UserList();
         $userList->getConditionBuilder()->add('user_table.userID IN (?)', [$this->parameters['userIDs']]);
 
-        return $userList->countObjects();
+        $this->count = $userList->countObjects();
     }
 
     /**
@@ -102,6 +102,7 @@ public function getProgress()
      * Resets the password of the given user.
      *
      * @param UserEditor $userEditor
+     * @return void
      */
     protected function resetPassword(UserEditor $userEditor)
     {
@@ -121,6 +122,7 @@ protected function resetPassword(UserEditor $userEditor)
      * Send links.
      *
      * @param User $user
+     * @return void
      */
     protected function sendLink(User $user)
     {
diff --git a/wcfsetup/install/files/lib/system/worker/SitemapRebuildWorker.class.php b/wcfsetup/install/files/lib/system/worker/SitemapRebuildWorker.class.php
index 3b98af9d380..1fb1817b152 100755
--- a/wcfsetup/install/files/lib/system/worker/SitemapRebuildWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/SitemapRebuildWorker.class.php
@@ -2,6 +2,7 @@
 
 namespace wcf\system\worker;
 
+use wcf\data\DatabaseObject;
 use wcf\data\DatabaseObjectList;
 use wcf\data\ILinkableObject;
 use wcf\data\object\type\ObjectType;
@@ -25,6 +26,8 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   3.1
+ *
+ * @phpstan-ignore missingType.generics
  */
 class SitemapRebuildWorker extends AbstractRebuildDataWorker
 {
@@ -186,7 +189,7 @@ public function execute()
                 $this->deleteSitemaps($this->sitemapObjects[$this->workerData['sitemap']]->objectType);
             }
 
-            /** @var DatabaseObjectList $objectList */
+            /** @var DatabaseObjectList<DatabaseObject> $objectList */
             $objectList = $sitemapObject->getObjectList();
 
             if (SITEMAP_INDEX_TIME_FRAME > 0 && $sitemapObject->getLastModifiedColumn() !== null) {
@@ -269,6 +272,8 @@ public function execute()
 
     /**
      * Checks if the sitemap has to be rebuilt. If not, this method marks the sitemap as built.
+     *
+     * @return void
      */
     protected function checkCache()
     {
@@ -308,6 +313,7 @@ protected function checkCache()
      * Writes the sitemap.xml index file and links all sitemaps.
      *
      * @param bool $closeFile Close a previously opened handle.
+     * @return void
      */
     protected function writeIndexFile($closeFile = true)
     {
@@ -335,6 +341,7 @@ protected function writeIndexFile($closeFile = true)
      * Generates a new temporary file and appends the sitemap start.
      *
      * @param bool $closeFile Close a previously opened handle.
+     * @return void
      */
     protected function generateTmpFile($closeFile = true)
     {
@@ -351,6 +358,8 @@ protected function generateTmpFile($closeFile = true)
 
     /**
      * Open the current temporary file.
+     *
+     * @return void
      */
     protected function openFile()
     {
@@ -363,6 +372,8 @@ protected function openFile()
 
     /**
      * Closes the current temporary file, iff a File is opened.
+     *
+     * @return void
      */
     protected function closeFile()
     {
@@ -377,6 +388,8 @@ protected function closeFile()
      *
      * @param string $filename
      * @param int $packageID
+     *
+     * @return void
      */
     protected function finishSitemap($filename, $packageID)
     {
@@ -395,7 +408,7 @@ protected function finishSitemap($filename, $packageID)
         $this->workerData['filesToPackage'][$packageID][] = 'sitemaps/' . $filename;
     }
 
-    private function registerSitemapFiles()
+    private function registerSitemapFiles(): void
     {
         $sql = "INSERT IGNORE INTO  wcf1_package_installation_file_log
                                     (packageID, filename, application)
@@ -417,6 +430,8 @@ private function registerSitemapFiles()
 
     /**
      * Stores the current worker data in a session.
+     *
+     * @return void
      */
     protected function storeWorkerData()
     {
@@ -425,6 +440,8 @@ protected function storeWorkerData()
 
     /**
      * Load the current worker data and set the default values, if isn't any data stored.
+     *
+     * @return void
      */
     protected function loadWorkerData()
     {
@@ -485,10 +502,8 @@ public static function getSitemapURL()
 
     /**
      * Unlink the sitemap files for a given object type name.
-     *
-     * @param string $objectTypeName
      */
-    private function deleteSitemaps($objectTypeName)
+    private function deleteSitemaps(string $objectTypeName): void
     {
         $files = @\glob(self::getSitemapPath() . $objectTypeName . '*.xml');
         if (\is_array($files)) {
@@ -504,7 +519,7 @@ private function deleteSitemaps($objectTypeName)
     /**
      * Saves the actual user and changes the session owner to a guest.
      */
-    private function changeUserToGuest()
+    private function changeUserToGuest(): void
     {
         $this->actualUser = WCF::getUser();
 
@@ -515,7 +530,7 @@ private function changeUserToGuest()
     /**
      * Changes the session back to the actual user.
      */
-    private function changeToActualUser()
+    private function changeToActualUser(): void
     {
         WCF::getSession()->changeUser($this->actualUser, true);
     }
@@ -523,7 +538,6 @@ private function changeToActualUser()
     /**
      * Reads the columns changed by the user for this sitemap object from the registry.
      *
-     * @param ObjectType $object
      * @since       5.3
      */
     private function prepareSitemapObject(ObjectType $object): void
diff --git a/wcfsetup/install/files/lib/system/worker/StatDailyRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/StatDailyRebuildDataWorker.class.php
index 1f9fe906c67..d9ab5e8cd82 100644
--- a/wcfsetup/install/files/lib/system/worker/StatDailyRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/StatDailyRebuildDataWorker.class.php
@@ -13,6 +13,8 @@
  * @author  Marcel Werk
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ *
+ * @phpstan-ignore missingType.generics
  */
 class StatDailyRebuildDataWorker extends AbstractRebuildDataWorker
 {
@@ -89,6 +91,8 @@ public function execute()
 
     /**
      * Determines the start timestamp.
+     *
+     * @return void
      */
     protected function getStartDate()
     {
diff --git a/wcfsetup/install/files/lib/system/worker/UnfurlUrlRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/UnfurlUrlRebuildDataWorker.class.php
index 193d0fddea3..15506e636d0 100644
--- a/wcfsetup/install/files/lib/system/worker/UnfurlUrlRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/UnfurlUrlRebuildDataWorker.class.php
@@ -16,7 +16,7 @@
  * @license     GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since       6.2
  *
- * @method  UnfurlUrlList    getObjectList()
+ * @extends AbstractLinearRebuildDataWorker<UnfurlUrlList>
  */
 final class UnfurlUrlRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/UserActivityPointItemsRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/UserActivityPointItemsRebuildDataWorker.class.php
index 1afd811596d..8bd99eb83ea 100644
--- a/wcfsetup/install/files/lib/system/worker/UserActivityPointItemsRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/UserActivityPointItemsRebuildDataWorker.class.php
@@ -19,7 +19,7 @@
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  * @since   5.2
  *
- * @method  UserList    getObjectList()
+ * @extends AbstractLinearRebuildDataWorker<UserList>
  */
 final class UserActivityPointItemsRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/UserActivityPointUpdateEventsWorker.class.php b/wcfsetup/install/files/lib/system/worker/UserActivityPointUpdateEventsWorker.class.php
index 18ede548da6..7934cab6a48 100644
--- a/wcfsetup/install/files/lib/system/worker/UserActivityPointUpdateEventsWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/UserActivityPointUpdateEventsWorker.class.php
@@ -27,9 +27,7 @@ class UserActivityPointUpdateEventsWorker extends AbstractWorker
      */
     public $objectTypes = [];
 
-    /**
-     * @inheritDoc
-     */
+    #[\Override]
     public function __construct(array $parameters)
     {
         parent::__construct($parameters);
diff --git a/wcfsetup/install/files/lib/system/worker/UserContentRemoveWorker.class.php b/wcfsetup/install/files/lib/system/worker/UserContentRemoveWorker.class.php
index 53c062a0476..78e24b9eb2e 100644
--- a/wcfsetup/install/files/lib/system/worker/UserContentRemoveWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/UserContentRemoveWorker.class.php
@@ -2,6 +2,8 @@
 
 namespace wcf\system\worker;
 
+use wcf\data\DatabaseObject;
+use wcf\data\DatabaseObjectList;
 use wcf\data\object\type\ObjectType;
 use wcf\data\object\type\ObjectTypeCache;
 use wcf\data\user\group\UserGroup;
@@ -129,7 +131,7 @@ public function validate()
     /**
      * Generate the data variable.
      */
-    private function generateData()
+    private function generateData(): void
     {
         $this->data = [
             'provider' => [],
@@ -177,7 +179,7 @@ private function generateData()
 
         foreach ($contentProviders as $contentProvider) {
             foreach ($this->users as $user) {
-                /** @var IUserContentProvider $processor */
+                /** @var IUserContentProvider<DatabaseObjectList<DatabaseObject>> $processor */
                 $processor = $contentProvider->getProcessor();
                 $contentList = $processor->getContentListForUser($user);
                 $count = $contentList->countObjects();
@@ -216,7 +218,7 @@ public function execute()
         $provideKey = \array_shift($providerIDs);
         $currentItem = $this->data['provider'][$provideKey];
 
-        /** @var IUserContentProvider $processor */
+        /** @var IUserContentProvider<DatabaseObjectList<DatabaseObject>> $processor */
         $processor = ObjectTypeCache::getInstance()->getObjectType($currentItem['objectTypeID'])->getProcessor();
         $user = new User($currentItem['userID']);
 
diff --git a/wcfsetup/install/files/lib/system/worker/UserRebuildDataWorker.class.php b/wcfsetup/install/files/lib/system/worker/UserRebuildDataWorker.class.php
index 951fc1a7943..912134028ea 100644
--- a/wcfsetup/install/files/lib/system/worker/UserRebuildDataWorker.class.php
+++ b/wcfsetup/install/files/lib/system/worker/UserRebuildDataWorker.class.php
@@ -29,7 +29,7 @@
  * @copyright   2001-2019 WoltLab GmbH
  * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
  *
- * @method  UserList    getObjectList()
+ * @extends AbstractLinearRebuildDataWorker<UserList>
  */
 final class UserRebuildDataWorker extends AbstractLinearRebuildDataWorker
 {
diff --git a/wcfsetup/install/files/lib/system/worker/event/RebuildWorkerCollecting.class.php b/wcfsetup/install/files/lib/system/worker/event/RebuildWorkerCollecting.class.php
index a35ebd53020..a4b0efb092a 100644
--- a/wcfsetup/install/files/lib/system/worker/event/RebuildWorkerCollecting.class.php
+++ b/wcfsetup/install/files/lib/system/worker/event/RebuildWorkerCollecting.class.php
@@ -18,6 +18,9 @@
  */
 class RebuildWorkerCollecting implements IEvent
 {
+    /**
+     * @var \SplPriorityQueue<int, RegisteredWorker>
+     */
     private \SplPriorityQueue $queue;
 
     public function __construct()
diff --git a/wcfsetup/install/files/lib/util/ArrayUtil.class.php b/wcfsetup/install/files/lib/util/ArrayUtil.class.php
index c44e35924cb..27a3a3fe190 100644
--- a/wcfsetup/install/files/lib/util/ArrayUtil.class.php
+++ b/wcfsetup/install/files/lib/util/ArrayUtil.class.php
@@ -16,11 +16,10 @@ final class ArrayUtil
     /**
      * Applies StringUtil::trim() to all elements of the given array.
      *
-     * @param array|string $array
-     * @param bool $removeEmptyElements
-     * @return  array|string
+     * @param mixed[]|string $array
+     * @return mixed[]|string
      */
-    public static function trim($array, $removeEmptyElements = true)
+    public static function trim(array|string $array, bool $removeEmptyElements = true): array|string
     {
         if (!\is_array($array)) {
             return StringUtil::trim($array);
@@ -41,10 +40,10 @@ public static function trim($array, $removeEmptyElements = true)
     /**
      * Applies intval() to all elements of the given array.
      *
-     * @param array|string $array
-     * @return  array|int
+     * @param (string|int)[]|string|int $array
+     * @return int[]|int
      */
-    public static function toIntegerArray($array)
+    public static function toIntegerArray(array|string|int $array): array|int
     {
         if (!\is_array($array)) {
             return \intval($array);
@@ -60,10 +59,10 @@ public static function toIntegerArray($array)
     /**
      * Converts html special characters in the given array.
      *
-     * @param array|string $array
-     * @return  array|string
+     * @param string[]|string $array
+     * @return string[]|string
      */
-    public static function encodeHTML($array)
+    public static function encodeHTML(array|string $array): array|string
     {
         if (!\is_array($array)) {
             return StringUtil::encodeHTML($array);
@@ -79,10 +78,10 @@ public static function encodeHTML($array)
     /**
      * Applies stripslashes on all elements of the given array.
      *
-     * @param array|string $array
-     * @return  array|string
+     * @param string[]|string $array
+     * @return string[]|string
      */
-    public static function stripslashes($array)
+    public static function stripslashes(array|string $array): array|string
     {
         if (!\is_array($array)) {
             return \stripslashes($array);
@@ -98,11 +97,10 @@ public static function stripslashes($array)
     /**
      * Appends a suffix to all elements of the given array.
      *
-     * @param array $array
-     * @param string $suffix
-     * @return  array
+     * @param string[] $array
+     * @return string[]
      */
-    public static function appendSuffix($array, $suffix)
+    public static function appendSuffix(array $array, string $suffix): array
     {
         foreach ($array as $key => $value) {
             $array[$key] = $value . $suffix;
@@ -114,10 +112,10 @@ public static function appendSuffix($array, $suffix)
     /**
      * Converts dos to unix newlines.
      *
-     * @param array|string $array
-     * @return  array|string
+     * @param string[]|string $array
+     * @return string[]|string
      */
-    public static function unifyNewlines($array)
+    public static function unifyNewlines(array|string $array): array|string
     {
         if (!\is_array($array)) {
             return StringUtil::unifyNewlines($array);
@@ -132,14 +130,12 @@ public static function unifyNewlines($array)
 
     /**
      * Converts a array of strings to requested character encoding.
-     * @param string $inCharset
-     * @param string $outCharset
-     * @param array|string $array
-     * @return  array|string
-     * @see mb_convert_encoding()
      *
+     * @param string[]|string $array
+     * @return string[]|string
+     * @see mb_convert_encoding()
      */
-    public static function convertEncoding($inCharset, $outCharset, $array)
+    public static function convertEncoding(string $inCharset, string $outCharset, array|string $array): array|string
     {
         if (!\is_array($array)) {
             return StringUtil::convertEncoding($inCharset, $outCharset, $array);
@@ -155,12 +151,10 @@ public static function convertEncoding($inCharset, $outCharset, $array)
     /**
      * Returns true when array1 has the same values as array2.
      *
-     * @param array $array1
-     * @param array $array2
-     * @param callable $callback
-     * @return  bool
+     * @param mixed[] $array1
+     * @param mixed[] $array2
      */
-    public static function compare(array $array1, array $array2, ?callable $callback = null)
+    public static function compare(array $array1, array $array2, ?callable $callback = null): bool
     {
         return static::compareHelper('value', $array1, $array2, $callback);
     }
@@ -168,12 +162,10 @@ public static function compare(array $array1, array $array2, ?callable $callback
     /**
      * Returns true when array1 has the same keys as array2.
      *
-     * @param array $array1
-     * @param array $array2
-     * @param callable $callback
-     * @return  bool
+     * @param mixed[] $array1
+     * @param mixed[] $array2
      */
-    public static function compareKey(array $array1, array $array2, ?callable $callback = null)
+    public static function compareKey(array $array1, array $array2, ?callable $callback = null): bool
     {
         return static::compareHelper('key', $array1, $array2, $callback);
     }
@@ -181,12 +173,10 @@ public static function compareKey(array $array1, array $array2, ?callable $callb
     /**
      * Compares array1 with array2 and returns true when they are identical.
      *
-     * @param array $array1
-     * @param array $array2
-     * @param callable $callback
-     * @return  bool
+     * @param mixed[] $array1
+     * @param mixed[] $array2
      */
-    public static function compareAssoc(array $array1, array $array2, ?callable $callback = null)
+    public static function compareAssoc(array $array1, array $array2, ?callable $callback = null): bool
     {
         return static::compareHelper('assoc', $array1, $array2, $callback);
     }
@@ -194,14 +184,11 @@ public static function compareAssoc(array $array1, array $array2, ?callable $cal
     /**
      * Does the actual comparison of the above compare methods.
      *
-     * @param string $method
-     * @param array $array1
-     * @param array $array2
-     * @param callable $callback
-     * @return  bool
+     * @param mixed[] $array1
+     * @param mixed[] $array2
      * @throws  SystemException
      */
-    protected static function compareHelper($method, array $array1, array $array2, ?callable $callback = null)
+    protected static function compareHelper(string $method, array $array1, array $array2, ?callable $callback = null): bool
     {
         // get function name
         $function = null;
diff --git a/wcfsetup/install/files/lib/util/CLIUtil.class.php b/wcfsetup/install/files/lib/util/CLIUtil.class.php
index 56b37142401..98d5c5987ca 100644
--- a/wcfsetup/install/files/lib/util/CLIUtil.class.php
+++ b/wcfsetup/install/files/lib/util/CLIUtil.class.php
@@ -17,10 +17,9 @@ final class CLIUtil
     /**
      * Generates a table.
      *
-     * @param array $table
-     * @return  string
+     * @param string[][] $table
      */
-    public static function generateTable(array $table)
+    public static function generateTable(array $table): string
     {
         $columnSize = [];
         foreach ($table as $row) {
@@ -68,10 +67,9 @@ public static function generateTable(array $table)
     /**
      * Generates a list.
      *
-     * @param array $list
-     * @return  string
+     * @param string[] $list
      */
-    public static function generateList(array $list)
+    public static function generateList(array $list): string
     {
         $result = '';
         foreach ($list as $row) {
diff --git a/wcfsetup/install/files/lib/util/CronjobUtil.class.php b/wcfsetup/install/files/lib/util/CronjobUtil.class.php
index a9b82f1438c..05e23cb7c2d 100644
--- a/wcfsetup/install/files/lib/util/CronjobUtil.class.php
+++ b/wcfsetup/install/files/lib/util/CronjobUtil.class.php
@@ -11,34 +11,31 @@ final class CronjobUtil
 {
     /**
      * indicates if day of month is restricted (not '*')
-     * @var bool
      */
-    protected static $domRestricted = false;
+    private static bool $domRestricted = false;
 
     /**
      * indicates if day of week is restricted (not '*')
-     * @var bool
      */
-    protected static $dowRestricted = false;
+    private static bool $dowRestricted = false;
 
     /**
      * result date
      * @var int[]
      */
-    protected static $result = [];
+    private static array $result = [];
 
     /**
      * time base used as reference for finding the next execution time
-     * @var int
      */
-    protected static $timeBase = 0;
+    private static int $timeBase = 0;
 
     /**
      * valid ranges for each known field (range for 'day of month' is missing
      * since it varies from month to month)
      * @var array<string, array{0: int, 1: int}>
      */
-    public static $ranges = [
+    public static array $ranges = [
         'minute' => [0, 59],
         'hour' => [0, 23],
         'dom' => [1, 31],
@@ -48,17 +45,15 @@ final class CronjobUtil
 
     /**
      * Calculates timestamp for next execution based on cron-like expressions and a given time base.
-     *
-     * @param string $minute
-     * @param string $hour
-     * @param string $dom
-     * @param string $month
-     * @param string $dow
-     * @param int $timeBase
-     * @return  int
      */
-    public static function calculateNextExec($minute, $hour, $dom, $month, $dow, $timeBase = TIME_NOW)
-    {
+    public static function calculateNextExec(
+        string $minute,
+        string $hour,
+        string $dom,
+        string $month,
+        string $dow,
+        int $timeBase = TIME_NOW
+    ): int {
         // using the native `date()` and `mktime()` functions is dangerous
         // unless we explicitly set the correct timezone
         $originalTimezone = \date_default_timezone_get();
@@ -146,9 +141,9 @@ public static function calculateNextExec($minute, $hour, $dom, $month, $dow, $ti
     /**
      * Calculates the date of next execution.
      *
-     * @param array $values
+     * @param mixed[] $values
      */
-    protected static function calculateTime(array &$values)
+    private static function calculateTime(array &$values): void
     {
         self::calculateDay($values);
     }
@@ -156,12 +151,10 @@ protected static function calculateTime(array &$values)
     /**
      * Calculates the next month and year to match given criteria.
      *
-     * @param int $month
-     * @param int $year
-     * @param array $values
-     * @return      array
+     * @param mixed[] $values
+     * @return int[]
      */
-    protected static function calculateMonth($month, $year, array &$values)
+    private static function calculateMonth(int $month, int $year, array &$values): array
     {
         $index = self::findKey($month, $values['month']);
 
@@ -183,10 +176,10 @@ protected static function calculateMonth($month, $year, array &$values)
      * of month, and day of week. If both fields are restricted , that is not '*', the
      * command will be run when either field matches the current time. -- crontab(5)
      *
-     * @param array $values
+     * @param mixed[] $values
      * @see     \wcf\util\CronjobUtil::getDom()
      */
-    protected static function calculateDay(array &$values)
+    private static function calculateDay(array &$values): void
     {
         $addAnDay = self::calculateHour($values, self::$timeBase);
         $timeBase = self::$timeBase;
@@ -262,13 +255,10 @@ protected static function calculateDay(array &$values)
     /**
      * Calculates the date of next execution based upon a given set for day of week.
      *
-     * @param int $month
-     * @param int $year
-     * @param array $values
-     * @param int $day
-     * @return  array
+     * @param mixed[] $values
+     * @return int[]
      */
-    protected static function calculateDow($month, $year, array &$values, $day = 1)
+    private static function calculateDow(int $month, int $year, array &$values, int $day = 1): array
     {
         $days = \date('t', \mktime(0, 0, 1, $month, $day, $year));
 
@@ -294,13 +284,10 @@ protected static function calculateDow($month, $year, array &$values, $day = 1)
     /**
      * Calculates the date of next execution based upon a given set for day of month.
      *
-     * @param int $month
-     * @param int $year
-     * @param array $values
-     * @param int $day
-     * @return  array
+     * @param mixed[] $values
+     * @return int[]
      */
-    protected static function calculateDom($month, $year, array &$values, $day = 1)
+    private static function calculateDom(int $month, int $year, array &$values, int $day = 1): array
     {
         $days = \date('t', \mktime(0, 0, 1, $month, $day, $year));
 
@@ -324,11 +311,9 @@ protected static function calculateDom($month, $year, array &$values, $day = 1)
      * Calculates hour of next execution. Returns true if hour-declaration
      * has already elapsed, thus requiring at least one day to be added.
      *
-     * @param array $values
-     * @param int $timeBase
-     * @return  bool
+     * @param mixed[] $values
      */
-    protected static function calculateHour(array &$values, &$timeBase)
+    private static function calculateHour(array &$values, int &$timeBase): bool
     {
         $addAnDay = false;
 
@@ -367,12 +352,9 @@ protected static function calculateHour(array &$values, &$timeBase)
      * Calculates minutes of next execution. Returns true if minute-declaration
      * has already elapsed, thus requiring at least one hour to be added.
      *
-     * @param array $values
-     * @param int $timeBase
-     * @param bool $addAnDay
-     * @return  bool
+     * @param mixed[] $values
      */
-    protected static function calculateMinute(array &$values, &$timeBase, $addAnDay)
+    private static function calculateMinute(array &$values, int &$timeBase, bool $addAnDay): bool
     {
         $addAnHour = false;
 
@@ -401,12 +383,9 @@ protected static function calculateMinute(array &$values, &$timeBase, $addAnDay)
      * needle. If $continue is not set to false and foreach-loop is out of bounds,
      * then the array-index '0' is returned, referring the first item.
      *
-     * @param int $needle
-     * @param array $haystack
-     * @param bool $continue
-     * @return  mixed
+     * @param mixed[] $haystack
      */
-    protected static function findKey($needle, array &$haystack, $continue = true)
+    private static function findKey(int $needle, array &$haystack, bool $continue = true): int|string|bool
     {
         $index = \array_search($needle, $haystack);
 
@@ -429,11 +408,9 @@ protected static function findKey($needle, array &$haystack, $continue = true)
     /**
      * Calculates all values matching possible expressions.
      *
-     * @param string $fieldName
-     * @param string $fieldValue
-     * @return  array
+     * @return int[]
      */
-    protected static function calculateValue($fieldName, $fieldValue)
+    private static function calculateValue(string $fieldName, string $fieldValue): array
     {
         $values = [];
 
@@ -467,10 +444,9 @@ protected static function calculateValue($fieldName, $fieldValue)
     /**
      * Tries to parse list items separated by a comma.
      *
-     * @param string $fieldValue
-     * @return  array
+     * @return list<string>
      */
-    protected static function getListItems($fieldValue)
+    private static function getListItems(string $fieldValue): array
     {
         if (\str_contains($fieldValue, ',')) {
             return \explode(',', $fieldValue);
@@ -482,14 +458,13 @@ protected static function getListItems($fieldValue)
     /**
      * Parses a possible range of values including a step value.
      *
-     * @param string $value
-     * @return  array
+     * @return list<int>
      */
-    protected static function getRanges($value)
+    private static function getRanges(string $value): array
     {
         // this is a single value
         if (!\str_contains($value, '-')) {
-            return [$value];
+            return [(int)$value];
         }
 
         $step = 1;
@@ -507,12 +482,9 @@ protected static function getRanges($value)
     /**
      * Calculates all values for a given range.
      *
-     * @param int $startValue
-     * @param int $endValue
-     * @param int $step
-     * @return  array
+     * @return list<int>
      */
-    protected static function calculateRange($startValue, $endValue, $step = 1)
+    private static function calculateRange(int $startValue, int $endValue, int $step = 1): array
     {
         $values = [];
 
@@ -525,15 +497,14 @@ protected static function calculateRange($startValue, $endValue, $step = 1)
 
     /**
      * Validates all cronjob attributes.
-     *
-     * @param string $startMinute
-     * @param string $startHour
-     * @param string $startDom
-     * @param string $startMonth
-     * @param string $startDow
      */
-    public static function validate($startMinute, $startHour, $startDom, $startMonth, $startDow)
-    {
+    public static function validate(
+        string $startMinute,
+        string $startHour,
+        string $startDom,
+        string $startMonth,
+        string $startDow
+    ): void {
         self::validateAttribute('startMinute', $startMinute);
         self::validateAttribute('startHour', $startHour);
         self::validateAttribute('startDom', $startDom);
@@ -544,11 +515,9 @@ public static function validate($startMinute, $startHour, $startDom, $startMonth
     /**
      * Validates a cronjob attribute.
      *
-     * @param string $name
-     * @param string $value
      * @throws  SystemException
      */
-    public static function validateAttribute($name, $value)
+    public static function validateAttribute(string $name, string $value): void
     {
         if ($value === '') {
             throw new SystemException("invalid value '" . $value . "' given for cronjob attribute '" . $name . "'");
diff --git a/wcfsetup/install/files/lib/util/DateUtil.class.php b/wcfsetup/install/files/lib/util/DateUtil.class.php
index 23146db385a..0deb6cd2aec 100644
--- a/wcfsetup/install/files/lib/util/DateUtil.class.php
+++ b/wcfsetup/install/files/lib/util/DateUtil.class.php
@@ -473,6 +473,7 @@ public static function getAge($date)
      * Validates if given date is valid ISO-8601.
      *
      * @param string $date
+     * @return void
      * @throws  SystemException
      */
     public static function validateDate($date)
diff --git a/wcfsetup/install/files/lib/util/Diff.class.php b/wcfsetup/install/files/lib/util/Diff.class.php
index 4ef06eb07aa..c7988a7cc24 100644
--- a/wcfsetup/install/files/lib/util/Diff.class.php
+++ b/wcfsetup/install/files/lib/util/Diff.class.php
@@ -36,13 +36,13 @@ class Diff
 
     /**
      * original array, as given by the user
-     * @var array
+     * @var list<string>
      */
     protected $a = [];
 
     /**
      * modified array, as given by the user
-     * @var array
+     * @var list<string>
      */
     protected $b = [];
 
@@ -60,12 +60,15 @@ class Diff
 
     /**
      * calculated diff
-     * @var array
+     * @var ?list<array{0: string, 1: string}>
      */
     protected $d;
 
     /**
      * @deprecated 6.0 Use sebastian/diff instead.
+     *
+     * @param list<string> $a
+     * @param list<string> $b
      */
     public function __construct(array $a, array $b)
     {
@@ -77,6 +80,7 @@ public function __construct(array $a, array $b)
     }
 
     /**
+     * @return \SplFixedArray<string>
      * @deprecated 6.0 Use sebastian/diff instead.
      */
     public function getLCS()
@@ -192,6 +196,8 @@ public function getLCS()
     /**
      * Builds the diff out of the longest common subsequence of `$this->a`
      * and `$this->b` and saves it in `$this->d`.
+     *
+     * @return void
      */
     protected function calculateDiff()
     {
@@ -230,6 +236,7 @@ protected function calculateDiff()
     }
 
     /**
+     * @return list<array{0: string, 1: string}>
      * @deprecated 6.0 Use sebastian/diff instead.
      */
     public function getRawDiff()
@@ -240,6 +247,8 @@ public function getRawDiff()
     }
 
     /**
+     * @param int $context
+     * @return string
      * @deprecated 6.0 Use sebastian/diff instead.
      */
     public function getUnixDiff($context = 2)
@@ -328,6 +337,8 @@ public function getUnixDiff($context = 2)
      * Transforms the output of sebastian/diff's Differ::diffToArray() into
      * the output of self::getRawDiff().
      *
+     * @param list<array{0: string, 1: int}> $arrayDiff
+     * @return list<array{0: string, 1: string}>
      * @since 6.0
      */
     public static function rawDiffFromSebastianDiff(array $arrayDiff): array
diff --git a/wcfsetup/install/files/lib/util/DirectoryUtil.class.php b/wcfsetup/install/files/lib/util/DirectoryUtil.class.php
index 2fa2e6e85fa..cc8fa83bc17 100644
--- a/wcfsetup/install/files/lib/util/DirectoryUtil.class.php
+++ b/wcfsetup/install/files/lib/util/DirectoryUtil.class.php
@@ -195,7 +195,7 @@ public function getFileObjects($order = \SORT_ASC, ?Regex $pattern = null, $nega
     /**
      * Fills the list of available files
      */
-    protected function scanFiles()
+    protected function scanFiles(): void
     {
         // value is cached
         if (!empty($this->files)) {
@@ -232,7 +232,7 @@ protected function scanFiles()
     /**
      * Fills the list of available files, with DirectoryIterator object as value
      */
-    protected function scanFileObjects()
+    protected function scanFileObjects(): void
     {
         // value is cached
         if (!empty($this->fileObjects)) {
@@ -271,9 +271,8 @@ protected function scanFileObjects()
      *
      * @param callable $callback
      * @param Regex $pattern callback is only applied to files matching the given pattern
-     * @return  bool
      */
-    public function executeCallback(callable $callback, ?Regex $pattern = null)
+    public function executeCallback(callable $callback, ?Regex $pattern = null): bool
     {
         if ($pattern !== null) {
             $files = $this->getFileObjects(self::SORT_NONE, $pattern);
@@ -291,7 +290,7 @@ public function executeCallback(callable $callback, ?Regex $pattern = null)
     /**
      * Recursive remove of directory.
      */
-    public function removeAll()
+    public function removeAll(): void
     {
         $this->removePattern(new Regex('.'));
 
@@ -306,7 +305,7 @@ public function removeAll()
      * @param bool $negativeMatch should the pattern be inversed
      * @throws  SystemException
      */
-    public function removePattern(Regex $pattern, $negativeMatch = false)
+    public function removePattern(Regex $pattern, $negativeMatch = false): void
     {
         if (!$this->recursive) {
             throw new SystemException('Removing of files only works in recursive mode');
@@ -332,10 +331,9 @@ public function removePattern(Regex $pattern, $negativeMatch = false)
     /**
      * Calculates the size of the directory.
      *
-     * @return  int     directory size in bytes
      * @throws  SystemException
      */
-    public function getSize()
+    public function getSize(): int
     {
         if (!$this->recursive) {
             throw new SystemException('Calculating of size only works in recursive mode');
@@ -357,7 +355,7 @@ public function getSize()
     /**
      * Clears the caches of the current instance
      */
-    public function clearCaches()
+    public function clearCaches(): void
     {
         // clear cached list of files
         $this->files = [];
diff --git a/wcfsetup/install/files/lib/util/ExifUtil.class.php b/wcfsetup/install/files/lib/util/ExifUtil.class.php
index 99516e50c5a..a454323e32e 100644
--- a/wcfsetup/install/files/lib/util/ExifUtil.class.php
+++ b/wcfsetup/install/files/lib/util/ExifUtil.class.php
@@ -79,10 +79,9 @@ private function __construct()
      * Returns the exif data of the image at the given location or an empty
      * array if the exif data can't be read.
      *
-     * @param string $filename
-     * @return  array
+     * @return mixed[]
      */
-    public static function getExifData($filename)
+    public static function getExifData(string $filename): array
     {
         if (\function_exists('exif_read_data')) {
             $exifData = @\exif_read_data($filename, '', true);
@@ -97,10 +96,9 @@ public static function getExifData($filename)
     /**
      * Returns the name of the used camera based on the given exif data.
      *
-     * @param array $exifData
-     * @return  string
+     * @param mixed[] $exifData
      */
-    public static function getCamera(array $exifData)
+    public static function getCamera(array $exifData): string
     {
         $camera = '';
         if (isset($exifData['IFD0'])) {
@@ -123,10 +121,9 @@ public static function getCamera(array $exifData)
     /**
      * Returns the creation timestamp based on the given exif data.
      *
-     * @param array $exifData
-     * @return  int
+     * @param mixed[] $exifData
      */
-    public static function getCreationTime(array $exifData)
+    public static function getCreationTime(array $exifData): int
     {
         $creationTime = 0;
         if (isset($exifData['EXIF'])) {
@@ -149,10 +146,9 @@ public static function getCreationTime(array $exifData)
      * Returns the longitude of the place the image with the given exif data
      * was taken.
      *
-     * @param array $exifData
-     * @return  float
+     * @param mixed[] $exifData
      */
-    public static function getLongitude(array $exifData)
+    public static function getLongitude(array $exifData): float
     {
         $longitude = 0;
         if (isset($exifData['GPS']) && isset($exifData['GPS']['GPSLongitudeRef']) && isset($exifData['GPS']['GPSLongitude'])) {
@@ -176,10 +172,9 @@ public static function getLongitude(array $exifData)
      * Returns the latitude of the place the image with the given exif data
      * was taken.
      *
-     * @param array $exifData
-     * @return  float
+     * @param mixed[] $exifData
      */
-    public static function getLatitude(array $exifData)
+    public static function getLatitude(array $exifData): int|float
     {
         $latitude = 0;
         if (isset($exifData['GPS']) && isset($exifData['GPS']['GPSLatitudeRef']) && isset($exifData['GPS']['GPSLatitude'])) {
@@ -202,10 +197,10 @@ public static function getLatitude(array $exifData)
     /**
      * Returns the formats exif data.
      *
-     * @param array $rawExifData
-     * @return  array
+     * @param mixed[] $rawExifData
+     * @return array<string, string|int|float>
      */
-    public static function getFormattedExifData(array $rawExifData)
+    public static function getFormattedExifData(array $rawExifData): array
     {
         $exifData = [];
 
@@ -236,10 +231,9 @@ public static function getFormattedExifData(array $rawExifData)
     /**
      * Returns the orientation of the image based on the given exif data.
      *
-     * @param array $exifData
-     * @return  int
+     * @param mixed[] $exifData
      */
-    public static function getOrientation(array $exifData)
+    public static function getOrientation(array $exifData): int
     {
         $orientation = self::ORIENTATION_ORIGINAL;
         if (isset($exifData['IFD0']['Orientation'])) {
@@ -312,7 +306,7 @@ private static function simplifyRational(string $rational): string
     /**
      * Implements the Euclidian Algorithm to calculate the GCD.
      */
-    private static function gcd(int $a, int $b)
+    private static function gcd(int $a, int $b): int
     {
         while ($b != 0) {
             $t = $b;
diff --git a/wcfsetup/install/files/lib/util/FileReader.class.php b/wcfsetup/install/files/lib/util/FileReader.class.php
index 0a1a260bf57..47515cd09fd 100644
--- a/wcfsetup/install/files/lib/util/FileReader.class.php
+++ b/wcfsetup/install/files/lib/util/FileReader.class.php
@@ -24,7 +24,7 @@ class FileReader
 
     /**
      * http options
-     * @var array
+     * @var array<string, string|int|bool>
      */
     protected $options = [
         'filename' => '',
@@ -39,7 +39,7 @@ class FileReader
 
     /**
      * list of header items
-     * @var array
+     * @var string[]
      */
     protected $headers = [];
 
@@ -65,7 +65,7 @@ class FileReader
      * Creates a new instance of the HTTPFileReader class.
      *
      * @param string $location
-     * @param array $options
+     * @param array<string, string|int|bool> $options
      * @throws  SystemException
      */
     public function __construct($location, array $options)
@@ -83,6 +83,8 @@ public function __construct($location, array $options)
 
     /**
      * Sends the file to the client.
+     *
+     * @return void
      */
     public function send()
     {
@@ -109,6 +111,8 @@ public function send()
 
     /**
      * Handles the given range options.
+     *
+     * @return void
      */
     protected function handleRange()
     {
@@ -144,6 +148,8 @@ protected function handleRange()
 
     /**
      * Handles the given header items.
+     *
+     * @return void
      */
     protected function handleHeaders()
     {
@@ -215,6 +221,9 @@ protected function getAsciiFilename(string $filename): string
 
     /**
      * @deprecated 6.0 This method is unused internally. Use `wcf\http\ContentDisposition` instead.
+     *
+     * @param string $filename
+     * @return string
      */
     protected function sanitizeFilename($filename)
     {
@@ -223,6 +232,8 @@ protected function sanitizeFilename($filename)
 
     /**
      * Sends the headers of the file to the client.
+     *
+     * @return void
      */
     protected function sendHeaders()
     {
@@ -237,6 +248,8 @@ protected function sendHeaders()
 
     /**
      * Sends the actual file to the client.
+     *
+     * @return void
      */
     protected function sendFile()
     {
@@ -263,7 +276,8 @@ protected function sendFile()
     /**
      * Sets the options for the http response.
      *
-     * @param array $options
+     * @param array<string, string|int|bool> $options
+     * @return void
      */
     public function setOptions(array $options)
     {
@@ -279,6 +293,7 @@ public function setOptions(array $options)
      *
      * @param string $name
      * @param string $value
+     * @return void
      */
     public function addHeader($name, $value)
     {
@@ -289,6 +304,7 @@ public function addHeader($name, $value)
      * Removes the header with the given name.
      *
      * @param string $name
+     * @return void
      */
     public function removeHeader($name)
     {
diff --git a/wcfsetup/install/files/lib/util/HTTPRequest.class.php b/wcfsetup/install/files/lib/util/HTTPRequest.class.php
index b5196dc6afb..b8a0d8aca1d 100644
--- a/wcfsetup/install/files/lib/util/HTTPRequest.class.php
+++ b/wcfsetup/install/files/lib/util/HTTPRequest.class.php
@@ -32,60 +32,53 @@ final class HTTPRequest
 {
     /**
      * given options
-     * @var array
+     * @var mixed[]
      */
-    private $options = [];
+    private array $options = [];
 
     /**
      * given post parameters
-     * @var array
+     * @var mixed[]
      */
-    private $postParameters = [];
+    private array $postParameters = [];
 
     /**
      * given files
-     * @var array
+     * @var mixed[]
      */
-    private $files = [];
+    private array $files = [];
 
     /**
      * request URL
-     * @var string
      */
-    private $url = '';
+    private string $url = '';
 
     /**
      * request headers
      * @var string[][]
      */
-    private $headers = [];
+    private array $headers = [];
 
     /**
      * request body
-     * @var string
      */
-    private $body = '';
+    private string $body = '';
 
     /**
      * reply body
-     * @var string
      */
-    private $replyBody;
+    private ?string $replyBody = null;
 
-    /**
-     * @var ?ResponseInterface
-     */
-    private $response;
+    private ?ResponseInterface $response = null;
 
     /**
      * Constructs a new instance of HTTPRequest.
      *
-     * @param string $url URL to connect to
-     * @param array $options
-     * @param mixed $postParameters Parameters to send via POST
-     * @param array $files Files to attach to the request
+     * @param mixed[] $options
+     * @param mixed[] $postParameters Parameters to send via POST
+     * @param mixed[] $files Files to attach to the request
      */
-    public function __construct($url, array $options = [], $postParameters = [], array $files = [])
+    public function __construct(string $url, array $options = [], array|string $postParameters = [], array $files = [])
     {
         $this->url = $url;
 
@@ -112,7 +105,7 @@ public function __construct($url, array $options = [], $postParameters = [], arr
             if (empty($this->files)) {
                 if (\is_array($postParameters)) {
                     $this->body = \http_build_query($this->postParameters, '', '&');
-                } elseif (\is_string($postParameters) && !empty($postParameters)) {
+                } elseif (\is_string($postParameters) && !empty($postParameters)) { // @phpstan-ignore function.alreadyNarrowedType
                     $this->body = $postParameters;
                 }
 
@@ -178,7 +171,7 @@ public function __construct($url, array $options = [], $postParameters = [], arr
     /**
      * Executes the HTTP request.
      */
-    public function execute()
+    public function execute(): void
     {
         $redirectHandler = function (RequestInterface $request, ResponseInterface $response, UriInterface $uri) {
             $this->url = (string)$uri;
@@ -282,9 +275,9 @@ public function execute()
      * Returns an array with the replied data.
      * Note that the 'headers' element is deprecated and may be removed in the future.
      *
-     * @return  array
+     * @return array{statusCode: int|string, headers: string[]|string[][], httpHeaders: string[]|string[][], body: string, url: string}
      */
-    public function getReply()
+    public function getReply(): array
     {
         if (!$this->response) {
             return [
@@ -342,10 +335,10 @@ public function getReply()
     /**
      * Sets options and applies default values when an option is omitted.
      *
-     * @param array $options
+     * @param mixed[] $options
      * @throws  \InvalidArgumentException
      */
-    private function setOptions(array $options)
+    private function setOptions(array $options): void
     {
         if (!isset($options['timeout'])) {
             $options['timeout'] = 10;
@@ -375,12 +368,8 @@ private function setOptions(array $options)
      * Adds a header to this request.
      * When an empty value is given existing headers of this name will be removed. When append
      * is set to false existing values will be overwritten.
-     *
-     * @param string $name
-     * @param string $value
-     * @param bool $append
      */
-    public function addHeader($name, $value, $append = false)
+    public function addHeader(string $name, string $value, bool $append = false): void
     {
         // 4.2 Field names are case-insensitive.
         $name = \strtolower($name);
diff --git a/wcfsetup/install/files/lib/util/HeaderUtil.class.php b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
index 402e7c49543..0ba840d70b5 100644
--- a/wcfsetup/install/files/lib/util/HeaderUtil.class.php
+++ b/wcfsetup/install/files/lib/util/HeaderUtil.class.php
@@ -28,18 +28,13 @@ final class HeaderUtil
 
     /**
      * output HTML
-     * @var string
      */
-    public static $output = '';
+    public static string $output = '';
 
     /**
      * Alias to php setcookie() function.
-     *
-     * @param string $name
-     * @param string $value
-     * @param int $expire
      */
-    public static function setCookie($name, $value = '', $expire = 0)
+    public static function setCookie(string $name, string $value = '', int $expire = 0): void
     {
         $cookieDomain = self::getCookieDomain();
 
@@ -81,7 +76,7 @@ public static function getCookieDomain(): ?string
     /**
      * Sends the headers of a page.
      */
-    public static function sendHeaders()
+    public static function sendHeaders(): void
     {
         // send content type
         @\header('Content-Type: text/html; charset=UTF-8');
@@ -97,7 +92,7 @@ public static function sendHeaders()
     /**
      * Sends no cache headers.
      */
-    public static function sendNoCacheHeaders()
+    public static function sendNoCacheHeaders(): void
     {
         @\header('Last-Modified: ' . \gmdate('D, d M Y H:i:s') . ' GMT');
         @\header('Cache-Control: max-age=0, no-cache, no-store, must-revalidate');
@@ -130,17 +125,12 @@ public static function withNoCacheHeaders(ResponseInterface $response): Response
     /**
      * @deprecated 5.4 - This method is a no-op, as gzip support was removed.
      */
-    public static function exceptionDisableGzip()
-    {
-    }
+    public static function exceptionDisableGzip(): void {}
 
     /**
      * Parses the rendered output.
-     *
-     * @param string $output
-     * @return  string
      */
-    public static function parseOutput($output)
+    public static function parseOutput(string $output): string
     {
         self::$output = $output;
 
@@ -235,12 +225,8 @@ public static function parseOutputStream(StreamInterface $input): StreamInterfac
 
     /**
      * Redirects the user agent to given location.
-     *
-     * @param string $location
-     * @param bool $sendStatusCode
-     * @param bool $temporaryRedirect
      */
-    public static function redirect($location, $sendStatusCode = false, $temporaryRedirect = true)
+    public static function redirect(string $location, bool $sendStatusCode = false, bool $temporaryRedirect = true): void
     {
         // https://github.com/WoltLab/WCF/issues/2568
         if (SessionHandler::getInstance()->isFirstVisit()) {
diff --git a/wcfsetup/install/files/lib/util/ImageUtil.class.php b/wcfsetup/install/files/lib/util/ImageUtil.class.php
index 9a7afdded6c..a2dc874e8af 100644
--- a/wcfsetup/install/files/lib/util/ImageUtil.class.php
+++ b/wcfsetup/install/files/lib/util/ImageUtil.class.php
@@ -189,7 +189,7 @@ public static function fixOrientation($filename)
                     }
 
                     $newFilename = FileUtil::getTemporaryFilename();
-                    $adapter->writeImage($newFilename);
+                    $adapter->writeImage($adapter->getImage(), $newFilename);
                     $filename = $newFilename;
                 }
             }
diff --git a/wcfsetup/install/files/lib/util/JSON.class.php b/wcfsetup/install/files/lib/util/JSON.class.php
index 78b09e1dd28..8da42a3abd8 100644
--- a/wcfsetup/install/files/lib/util/JSON.class.php
+++ b/wcfsetup/install/files/lib/util/JSON.class.php
@@ -15,12 +15,8 @@ final class JSON
 {
     /**
      * Returns the JSON representation of a value.
-     *
-     * @param mixed $data
-     * @param int $options
-     * @return  string
      */
-    public static function encode($data, $options = 0)
+    public static function encode(mixed $data, int $options = 0): string
     {
         return \json_encode($data, $options);
     }
@@ -28,12 +24,10 @@ public static function encode($data, $options = 0)
     /**
      * Decodes a JSON string.
      *
-     * @param string $json
-     * @param bool $asArray
-     * @return  array
+     * @return mixed[]
      * @throws  SystemException
      */
-    public static function decode($json, $asArray = true)
+    public static function decode(string $json, bool $asArray = true): array
     {
         $data = @\json_decode($json, $asArray);
 
@@ -50,10 +44,8 @@ public static function decode($json, $asArray = true)
 
     /**
      * Returns the last error occurred.
-     *
-     * @return  int
      */
-    public static function getLastError()
+    public static function getLastError(): int
     {
         return \json_last_error();
     }
diff --git a/wcfsetup/install/files/lib/util/MathUtil.class.php b/wcfsetup/install/files/lib/util/MathUtil.class.php
index 78bf9bc7f2c..4f06c5c7b97 100644
--- a/wcfsetup/install/files/lib/util/MathUtil.class.php
+++ b/wcfsetup/install/files/lib/util/MathUtil.class.php
@@ -14,7 +14,7 @@ final class MathUtil
     /**
      * @deprecated 5.5 - Use `\random_int()` or `\mt_rand()` directly.
      */
-    public static function getRandomValue($min = null, $max = null)
+    public static function getRandomValue(?int $min = null, ?int $max = null): int
     {
         // generate random value
         return ($min !== null && $max !== null) ? \mt_rand($min, $max) : \mt_rand();
@@ -24,11 +24,9 @@ public static function getRandomValue($min = null, $max = null)
      * Transforms the given latitude and longitude into cartesian coordinates
      * (x, y, z).
      *
-     * @param float $latitude
-     * @param float $longitude
-     * @return  float[]
+     * @return array{0: float, 1: float, 2: float}
      */
-    public static function latitudeLongitudeToCartesian($latitude, $longitude)
+    public static function latitudeLongitudeToCartesian(float $latitude, float $longitude): array
     {
         $lambda = $longitude * \M_PI / 180;
         $phi = $latitude * \M_PI / 180;
diff --git a/wcfsetup/install/files/lib/util/OptionUtil.class.php b/wcfsetup/install/files/lib/util/OptionUtil.class.php
index a9d5c49966a..1eea56a2f12 100644
--- a/wcfsetup/install/files/lib/util/OptionUtil.class.php
+++ b/wcfsetup/install/files/lib/util/OptionUtil.class.php
@@ -14,10 +14,9 @@ final class OptionUtil
     /**
      * Returns a list of the available options.
      *
-     * @param string $selectOptions
-     * @return  array
+     * @return array<string, string>
      */
-    public static function parseSelectOptions($selectOptions)
+    public static function parseSelectOptions(string $selectOptions): array
     {
         $result = [];
         $options = \explode("\n", StringUtil::trim(StringUtil::unifyNewlines($selectOptions)));
@@ -38,10 +37,9 @@ public static function parseSelectOptions($selectOptions)
     /**
      * Returns a list of the enable options.
      *
-     * @param string $enableOptions
-     * @return  array
+     * @return array<string, string>
      */
-    public static function parseMultipleEnableOptions($enableOptions)
+    public static function parseMultipleEnableOptions(string $enableOptions): array
     {
         $result = [];
         if (!empty($enableOptions)) {
diff --git a/wcfsetup/install/files/lib/util/PasswordUtil.class.php b/wcfsetup/install/files/lib/util/PasswordUtil.class.php
index 606edf363c6..0486d97e82c 100644
--- a/wcfsetup/install/files/lib/util/PasswordUtil.class.php
+++ b/wcfsetup/install/files/lib/util/PasswordUtil.class.php
@@ -18,12 +18,13 @@ final class PasswordUtil
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    private static $blowfishCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789./';
+    private static string $blowfishCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789./';
 
     /**
      * @deprecated  5.5 - After the removal of other deprecated methods this would effectively be empty.
+     * @var string[]
      */
-    private static $supportedEncryptionTypes = [
+    private static array $supportedEncryptionTypes = [
         'argon2',   // vBulletin 5.x
         'ipb2',     // Invision Power Board 2.x
         'ipb3',     // Invision Power Board 3.x
@@ -61,7 +62,7 @@ final class PasswordUtil
     /**
      * @deprecated  5.5 - After the removal of other deprecated methods this would effectively always return false.
      */
-    public static function isSupported($type)
+    public static function isSupported(string $type): bool
     {
         if (\in_array($type, self::$supportedEncryptionTypes)) {
             return true;
@@ -77,7 +78,7 @@ public static function isSupported($type)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function isBlowfish($hash)
+    public static function isBlowfish(string $hash): bool
     {
         return Regex::compile('^\$2[afxy]\$')->match($hash) ? true : false;
     }
@@ -85,7 +86,7 @@ public static function isBlowfish($hash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function isDifferentBlowfish($hash)
+    public static function isDifferentBlowfish(string $hash): bool
     {
         $currentCost = \intval(self::BCRYPT_COST);
         $hashCost = \intval(\substr($hash, 4, 2));
@@ -100,7 +101,7 @@ public static function isDifferentBlowfish($hash)
     /**
      * @deprecated  5.5 - After the removal of other deprecated methods this would effectively always return false.
      */
-    public static function checkPassword($username, $password, $dbHash)
+    public static function checkPassword(string $username, string $password, string $dbHash): bool
     {
         $type = self::detectEncryption($dbHash);
         if ($type === 'unknown') {
@@ -131,7 +132,7 @@ public static function checkPassword($username, $password, $dbHash)
     /**
      * @deprecated  5.5 - After the removal of other deprecated methods this would effectively always return 'unknown'.
      */
-    public static function detectEncryption($hash)
+    public static function detectEncryption(string $hash): string
     {
         if (($pos = \strpos($hash, ':')) !== false) {
             $type = \substr($hash, 0, $pos);
@@ -146,7 +147,7 @@ public static function detectEncryption($hash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function getDoubleSaltedHash($password, $salt = null)
+    public static function getDoubleSaltedHash(string $password, ?string $salt = null): string
     {
         if ($salt === null) {
             $salt = self::getRandomSalt();
@@ -158,7 +159,7 @@ public static function getDoubleSaltedHash($password, $salt = null)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function getSaltedHash($password, $salt = null)
+    public static function getSaltedHash(string $password, ?string $salt = null): string
     {
         if ($salt === null) {
             $salt = self::getRandomSalt();
@@ -170,7 +171,7 @@ public static function getSaltedHash($password, $salt = null)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function getRandomSalt()
+    public static function getRandomSalt(): string
     {
         $salt = '';
 
@@ -184,7 +185,7 @@ public static function getRandomSalt()
     /**
      * @deprecated 5.5 - Use some constant time encoder (e.g. Hex, Base32, or Base64) on the result of `\random_bytes()`.
      */
-    public static function getRandomPassword($length = 12)
+    public static function getRandomPassword(int $length = 12): string
     {
         $charset = self::PASSWORD_CHARSET;
         $password = '';
@@ -199,7 +200,7 @@ public static function getRandomPassword($length = 12)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function getSalt($salt)
+    private static function getSalt(string $salt): string
     {
         $salt = \mb_substr($salt, 0, 22);
 
@@ -209,7 +210,7 @@ protected static function getSalt($salt)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function argon2($username, $password, $salt, $dbHash)
+    private static function argon2(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \password_verify($password, $dbHash);
     }
@@ -217,7 +218,7 @@ protected static function argon2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function ipb2($username, $password, $salt, $dbHash)
+    private static function ipb2(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::vb3($username, $password, $salt, $dbHash);
     }
@@ -225,7 +226,7 @@ protected static function ipb2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function ipb3($username, $password, $salt, $dbHash)
+    private static function ipb3(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, \md5(\md5($salt) . \md5($password)));
     }
@@ -233,7 +234,7 @@ protected static function ipb3($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function mybb1($username, $password, $salt, $dbHash)
+    private static function mybb1(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, \md5(\md5($salt) . \md5($password)));
     }
@@ -241,7 +242,7 @@ protected static function mybb1($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    public static function phpbb3($username, $password, $salt, $dbHash)
+    public static function phpbb3(string $username, string $password, string $salt, string $dbHash): bool
     {
         $phpassResult = self::phpass($username, $password, $salt, $dbHash);
 
@@ -285,7 +286,7 @@ public static function phpbb3($username, $password, $salt, $dbHash)
         return \hash_equals($dbHash, $password);
     }
 
-    private static function phpassHashCryptPrivate($password, $setting)
+    private static function phpassHashCryptPrivate(string $password, string $setting): string
     {
         static $itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
 
@@ -357,7 +358,7 @@ private static function phpassHashCryptPrivate($password, $setting)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function phpass($username, $password, $salt, $dbHash)
+    private static function phpass(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\mb_strlen($dbHash) !== 34) {
             return \hash_equals(\md5($password), $dbHash);
@@ -369,7 +370,7 @@ protected static function phpass($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function smf1($username, $password, $salt, $dbHash)
+    private static function smf1(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, \sha1(\mb_strtolower($username) . $password));
     }
@@ -377,7 +378,7 @@ protected static function smf1($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function smf2($username, $password, $salt, $dbHash)
+    private static function smf2(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::smf1($username, $password, $salt, $dbHash);
     }
@@ -385,7 +386,7 @@ protected static function smf2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function vb3($username, $password, $salt, $dbHash)
+    private static function vb3(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, \md5(\md5($password) . $salt));
     }
@@ -393,7 +394,7 @@ protected static function vb3($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function vb4($username, $password, $salt, $dbHash)
+    private static function vb4(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::vb3($username, $password, $salt, $dbHash);
     }
@@ -401,7 +402,7 @@ protected static function vb4($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function vb5($username, $password, $salt, $dbHash)
+    private static function vb5(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::vb3($username, $password, $salt, $dbHash);
     }
@@ -409,7 +410,7 @@ protected static function vb5($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function wbb2($username, $password, $salt, $dbHash)
+    private static function wbb2(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, \md5($password))) {
             return true;
@@ -423,7 +424,7 @@ protected static function wbb2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function wcf1($username, $password, $salt, $dbHash)
+    private static function wcf1(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, \sha1($salt . \sha1($salt . \sha1($password))));
     }
@@ -431,7 +432,7 @@ protected static function wcf1($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function wcf1e($type, $password, $salt, $dbHash)
+    private static function wcf1e(string $type, string $password, string $salt, string $dbHash): bool
     {
         \preg_match('~^wcf1e([cms])([01])([ab])([01])$~', $type, $matches);
         $enableSalting = $matches[2];
@@ -481,7 +482,7 @@ protected static function wcf1e($type, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function wcf2($username, $password, $salt, $dbHash)
+    private static function wcf2(string $username, string $password, string $salt, string $dbHash): bool
     {
         return \hash_equals($dbHash, self::getDoubleSaltedHash($password, $dbHash));
     }
@@ -489,7 +490,7 @@ protected static function wcf2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function xf1($username, $password, $salt, $dbHash)
+    private static function xf1(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, \sha1(\sha1($password) . $salt))) {
             return true;
@@ -501,7 +502,7 @@ protected static function xf1($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function xf12($username, $password, $salt, $dbHash)
+    private static function xf12(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, self::getSaltedHash($password, $dbHash))) {
             return true;
@@ -513,7 +514,7 @@ protected static function xf12($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function joomla1($username, $password, $salt, $dbHash)
+    private static function joomla1(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, \md5($password . $salt))) {
             return true;
@@ -525,7 +526,7 @@ protected static function joomla1($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function joomla2($username, $password, $salt, $dbHash)
+    private static function joomla2(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::joomla1($username, $password, $salt, $dbHash);
     }
@@ -533,7 +534,7 @@ protected static function joomla2($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function joomla3($username, $password, $salt, $dbHash)
+    private static function joomla3(string $username, string $password, string $salt, string $dbHash): bool
     {
         return self::joomla1($username, $password, $salt, $dbHash);
     }
@@ -541,7 +542,7 @@ protected static function joomla3($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function phpfox3($username, $password, $salt, $dbHash)
+    private static function phpfox3(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, \md5(\md5($password) . \md5($salt)))) {
             return true;
@@ -553,7 +554,7 @@ protected static function phpfox3($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function cryptMD5($username, $password, $salt, $dbHash)
+    private static function cryptMD5(string $username, string $password, string $salt, string $dbHash): bool
     {
         if (\hash_equals($dbHash, self::getSaltedHash($password, $dbHash))) {
             return true;
@@ -565,7 +566,7 @@ protected static function cryptMD5($username, $password, $salt, $dbHash)
     /**
      * @deprecated  5.4 - Use the new password algorithm framework in \wcf\system\user\authentication\password\*.
      */
-    protected static function invalid($username, $password, $salt, $dbHash)
+    private static function invalid(string $username, string $password, string $salt, string $dbHash): bool
     {
         return false;
     }
diff --git a/wcfsetup/install/files/lib/util/StringStack.class.php b/wcfsetup/install/files/lib/util/StringStack.class.php
index aee3cb394f3..cd8de773871 100644
--- a/wcfsetup/install/files/lib/util/StringStack.class.php
+++ b/wcfsetup/install/files/lib/util/StringStack.class.php
@@ -13,26 +13,23 @@ final class StringStack
 {
     /**
      * hash index
-     * @var int
      */
-    protected static $i = 0;
+    private static int $i = 0;
 
     /**
      * local string stack
-     * @var string[][]
+     * @var array<string, array<string, string>>
      */
-    protected static $stringStack = [];
+    private static array $stringStack = [];
 
     /**
      * Replaces a string with an unique hash value.
-     *
-     * @param string $string
-     * @param string $type
-     * @param string $delimiter
-     * @return  string      $hash
      */
-    public static function pushToStringStack($string, $type = 'default', $delimiter = '@@')
-    {
+    public static function pushToStringStack(
+        string $string,
+        string $type = 'default',
+        string $delimiter = '@@'
+    ): string {
         self::$i++;
         $hash = $delimiter . StringUtil::getRandomID() . $delimiter;
 
@@ -47,12 +44,8 @@ public static function pushToStringStack($string, $type = 'default', $delimiter
 
     /**
      * Reinserts strings that have been replaced by unique hash values.
-     *
-     * @param string $string
-     * @param string $type
-     * @return  string
      */
-    public static function reinsertStrings($string, $type = 'default')
+    public static function reinsertStrings(string $string, string $type = 'default'): string
     {
         if (isset(self::$stringStack[$type])) {
             foreach (self::$stringStack[$type] as $hash => $value) {
@@ -69,10 +62,9 @@ public static function reinsertStrings($string, $type = 'default')
     /**
      * Returns the stack.
      *
-     * @param string $type
-     * @return  array
+     * @return array<string, string>
      */
-    public static function getStack($type = 'default')
+    public static function getStack(string $type = 'default'): array
     {
         if (isset(self::$stringStack[$type])) {
             return self::$stringStack[$type];
diff --git a/wcfsetup/install/files/lib/util/StringUtil.class.php b/wcfsetup/install/files/lib/util/StringUtil.class.php
index e69896add5d..f5074c99670 100644
--- a/wcfsetup/install/files/lib/util/StringUtil.class.php
+++ b/wcfsetup/install/files/lib/util/StringUtil.class.php
@@ -31,17 +31,15 @@ final class StringUtil
     /**
      * @deprecated 5.5 - Use \sha1() directly.
      */
-    public static function getHash($value)
+    public static function getHash(string $value): string
     {
         return \sha1($value);
     }
 
     /**
      * Returns a 40 character hexadecimal string generated using a CSPRNG.
-     *
-     * @return  string
      */
-    public static function getRandomID()
+    public static function getRandomID(): string
     {
         return Hex::encode(\random_bytes(20));
     }
@@ -73,10 +71,8 @@ public static function getUUID(): string
 
     /**
      * Converts dos to unix newlines.
-     *
-     * @param string $string
      */
-    public static function unifyNewlines($string): string
+    public static function unifyNewlines(string $string): string
     {
         return \preg_replace("%(\r\n)|(\r)%", "\n", $string);
     }
@@ -84,10 +80,8 @@ public static function unifyNewlines($string): string
     /**
      * Removes Unicode whitespace characters from the beginning
      * and ending of the given string.
-     *
-     * @param string $text
      */
-    public static function trim($text): string
+    public static function trim(string $text): string
     {
         // $boundaryCharacters can always be removed when appearing at either the beginning
         // or the end of the input.
@@ -142,13 +136,19 @@ public static function trim($text): string
 
     /**
      * Converts html special characters.
-     *
-     * @param string $string
      */
-    public static function encodeHTML($string): string
+    public static function encodeHTML(?string $string): string
     {
+        // Until 6.1 this function implicitly casted values to string which made
+        // it possible to invoke it with null values. There is little value in
+        // breaking the compatibility therefore we will keep accepting those for
+        // the time being.
+        if ($string === null) {
+            return '';
+        }
+
         return @\htmlspecialchars(
-            (string)$string,
+            $string,
             \ENT_QUOTES | \ENT_SUBSTITUTE | \ENT_HTML401,
             'UTF-8'
         );
@@ -156,10 +156,8 @@ public static function encodeHTML($string): string
 
     /**
      * Converts javascript special characters.
-     *
-     * @param string $string
      */
-    public static function encodeJS($string): string
+    public static function encodeJS(string $string): string
     {
         $string = self::unifyNewlines($string);
 
@@ -168,10 +166,8 @@ public static function encodeJS($string): string
 
     /**
      * Decodes html entities.
-     *
-     * @param string $string
      */
-    public static function decodeHTML($string): string
+    public static function decodeHTML(string $string): string
     {
         $string = \str_ireplace('&nbsp;', ' ', $string); // convert non-breaking spaces to ascii 32; not ascii 160
 
@@ -244,10 +240,8 @@ public static function addThousandsSeparator(int|float $number): string
 
     /**
      * Replaces the MINUS-HYPHEN with the MINUS SIGN.
-     *
-     * @param mixed $number
      */
-    public static function formatNegative($number): string
+    public static function formatNegative(string $number): string
     {
         return \str_replace('-', self::MINUS, $number);
     }
@@ -255,9 +249,9 @@ public static function formatNegative($number): string
     /**
      * Alias to php ucfirst() function with multibyte support.
      *
-     * @param string $string
+     * @deprecated 6.2 Use `\mb_ucfirst()` instead
      */
-    public static function firstCharToUpperCase($string): string
+    public static function firstCharToUpperCase(string $string): string
     {
         return \mb_strtoupper(\mb_substr($string, 0, 1)) . \mb_substr($string, 1);
     }
@@ -265,19 +259,17 @@ public static function firstCharToUpperCase($string): string
     /**
      * Alias to php lcfirst() function with multibyte support.
      *
-     * @param string $string
+     * @deprecated 6.2 Use `\mb_lcfirst()` instead
      */
-    public static function firstCharToLowerCase($string): string
+    public static function firstCharToLowerCase(string $string): string
     {
         return \mb_strtolower(\mb_substr($string, 0, 1)) . \mb_substr($string, 1);
     }
 
     /**
      * Alias to php mb_convert_case() function.
-     *
-     * @param string $string
      */
-    public static function wordsToUpperCase($string): string
+    public static function wordsToUpperCase(string $string): string
     {
         return \mb_convert_case($string, \MB_CASE_TITLE);
     }
@@ -287,13 +279,8 @@ public static function wordsToUpperCase($string): string
      *
      * This function is considered to be slow, if $search contains
      * only ASCII characters, please use str_ireplace() instead.
-     *
-     * @param string $search
-     * @param string $replace
-     * @param string $subject
-     * @param int $count
      */
-    public static function replaceIgnoreCase($search, $replace, $subject, &$count = 0): string
+    public static function replaceIgnoreCase(string $search, string $replace, string $subject, int &$count = 0): string
     {
         $startPos = \mb_strpos(\mb_strtolower($subject), \mb_strtolower($search));
         if ($startPos === false) {
@@ -312,9 +299,10 @@ public static function replaceIgnoreCase($search, $replace, $subject, &$count =
     }
 
     /**
+     * @return list<string>
      * @deprecated 5.5 Use \mb_str_split() instead.
      */
-    public static function split($string, $length = 1)
+    public static function split(string $string, int $length = 1): array
     {
         $result = [];
         for ($i = 0, $max = \mb_strlen($string); $i < $max; $i += $length) {
@@ -327,7 +315,7 @@ public static function split($string, $length = 1)
     /**
      * @deprecated 5.5 Use \str_starts_with() instead. If a case-insensitive comparison is desired, manually call \mb_strtolower on both parameters.
      */
-    public static function startsWith($haystack, $needle, $ci = false): bool
+    public static function startsWith(string $haystack, string $needle, bool $ci = false): bool
     {
         if ($ci) {
             $haystack = \mb_strtolower($haystack);
@@ -340,7 +328,7 @@ public static function startsWith($haystack, $needle, $ci = false): bool
     /**
      * @deprecated 5.5 Use \str_ends_with() instead. If a case-insensitive comparison is desired, manually call \mb_strtolower on both parameters.
      */
-    public static function endsWith($haystack, $needle, $ci = false): bool
+    public static function endsWith(string $haystack, string $needle, bool $ci = false): bool
     {
         if ($ci) {
             $haystack = \mb_strtolower($haystack);
@@ -356,13 +344,8 @@ public static function endsWith($haystack, $needle, $ci = false): bool
 
     /**
      * Alias to php str_pad function with multibyte support.
-     *
-     * @param string $input
-     * @param int $padLength
-     * @param string $padString
-     * @param int $padType
      */
-    public static function pad($input, $padLength, $padString = ' ', $padType = \STR_PAD_RIGHT): string
+    public static function pad(string $input, int $padLength, string  $padString = ' ', int $padType = \STR_PAD_RIGHT): string
     {
         $additionalPadding = \strlen($input) - \mb_strlen($input);
 
@@ -371,11 +354,8 @@ public static function pad($input, $padLength, $padString = ' ', $padType = \STR
 
     /**
      * Unescapes escaped characters in a string.
-     *
-     * @param string $string
-     * @param string $chars
      */
-    public static function unescape($string, $chars = '"'): string
+    public static function unescape(string $string, string $chars = '"'): string
     {
         for ($i = 0, $j = \strlen($chars); $i < $j; $i++) {
             $string = \str_replace('\\' . $chars[$i], $chars[$i], $string);
@@ -386,10 +366,8 @@ public static function unescape($string, $chars = '"'): string
 
     /**
      * Takes a numeric HTML entity value and returns the appropriate UTF-8 bytes.
-     *
-     * @param int $dec html entity value
      */
-    public static function getCharacter($dec): string
+    public static function getCharacter(int $dec): string
     {
         if ($dec < 128) {
             $utf = \chr($dec);
@@ -408,11 +386,8 @@ public static function getCharacter($dec): string
     /**
      * Converts UTF-8 to Unicode
      * @see     http://www1.tip.nl/~t876506/utf8tbl.html
-     *
-     * @param string $c
-     * @return  int
      */
-    public static function getCharValue($c)
+    public static function getCharValue(string $c): int
     {
         $ud = 0;
         if (\ord($c[0]) <= 127) {
@@ -442,10 +417,8 @@ public static function getCharValue($c)
 
     /**
      * Returns html entities of all characters in the given string.
-     *
-     * @param string $string
      */
-    public static function encodeAllChars($string): string
+    public static function encodeAllChars(string $string): string
     {
         $result = '';
         for ($i = 0, $j = \mb_strlen($string); $i < $j; $i++) {
@@ -458,10 +431,8 @@ public static function encodeAllChars($string): string
 
     /**
      * Returns true if the given string contains only ASCII characters.
-     *
-     * @param string $string
      */
-    public static function isASCII($string): bool
+    public static function isASCII(string $string): bool
     {
         return !!\preg_match('/^[\x00-\x7F]*$/', $string);
     }
@@ -469,11 +440,8 @@ public static function isASCII($string): bool
     /**
      * Returns true if the given string is utf-8 encoded.
      * @see     http://www.w3.org/International/questions/qa-forms-utf-8
-     *
-     * @param string $string
-     * @return  bool
      */
-    public static function isUTF8($string): bool
+    public static function isUTF8(string $string): bool
     {
         return !!\preg_match('/^(
 				[\x09\x0A\x0D\x20-\x7E]*		# ASCII
@@ -489,10 +457,8 @@ public static function isUTF8($string): bool
 
     /**
      * Escapes the closing cdata tag.
-     *
-     * @param string $string
      */
-    public static function escapeCDATA($string): string
+    public static function escapeCDATA(string $string): string
     {
         return \str_replace(']]>', ']]]]><![CDATA[>', $string);
     }
@@ -500,17 +466,15 @@ public static function escapeCDATA($string): string
     /**
      * @deprecated 6.0 Use `\mb_convert_encoding()` directly.
      */
-    public static function convertEncoding($inCharset, $outCharset, $string): string
+    public static function convertEncoding(string $inCharset, string $outCharset, string $string): string
     {
         return \mb_convert_encoding($string, $outCharset, $inCharset);
     }
 
     /**
      * Strips HTML tags from a string.
-     *
-     * @param string $string
      */
-    public static function stripHTML($string): string
+    public static function stripHTML(string $string): string
     {
         $string = \preg_replace('~<!--(.*?)-->~', '', $string);
 
@@ -533,11 +497,8 @@ public static function stripHTML($string): string
 
     /**
      * Returns false if the given word is forbidden by given word filter.
-     *
-     * @param string $word
-     * @param string $filter
      */
-    public static function executeWordFilter($word, $filter): bool
+    public static function executeWordFilter(string $word, string $filter): bool
     {
         $filter = self::trim($filter);
         $word = \mb_strtolower($word);
@@ -569,14 +530,13 @@ public static function executeWordFilter($word, $filter): bool
 
     /**
      * Truncates the given string to a certain number of characters.
-     *
-     * @param string $string string which shall be truncated
-     * @param int $length string length after truncating
-     * @param string $etc string to append when $string is truncated
-     * @param bool $breakWords should words be broken in the middle
      */
-    public static function truncate($string, $length = 80, $etc = self::HELLIP, $breakWords = false): string
-    {
+    public static function truncate(
+        string $string,
+        int $length = 80,
+        string $etc = self::HELLIP,
+        bool $breakWords = false
+    ): string {
         if ($length == 0) {
             return '';
         }
@@ -596,14 +556,13 @@ public static function truncate($string, $length = 80, $etc = self::HELLIP, $bre
 
     /**
      * Truncates a string containing HTML code and keeps the HTML syntax intact.
-     *
-     * @param string $string string which shall be truncated
-     * @param int $length string length after truncating
-     * @param string $etc ending string which will be appended after truncating
-     * @param bool $breakWords if false words will not be split and the return string might be shorter than $length
      */
-    public static function truncateHTML($string, $length = 500, $etc = self::HELLIP, $breakWords = false): string
-    {
+    public static function truncateHTML(
+        string $string,
+        int $length = 500,
+        string $etc = self::HELLIP,
+        bool $breakWords = false
+    ): string {
         if (\mb_strlen(self::stripHTML($string)) <= $length) {
             return $string;
         }
@@ -696,14 +655,13 @@ public static function truncateHTML($string, $length = 500, $etc = self::HELLIP,
 
     /**
      * Generates an anchor tag from given URL.
-     *
-     * @param string $url
-     * @param string $title
-     * @param bool $encodeTitle
-     * @param bool $isUgc true to add rel=ugc to the anchor tag
      */
-    public static function getAnchorTag($url, $title = '', $encodeTitle = true, $isUgc = false): string
-    {
+    public static function getAnchorTag(
+        string $url,
+        string $title = '',
+        bool $encodeTitle = true,
+        bool $isUgc = false
+    ): string {
         $url = self::trim($url);
 
         // cut visible url
@@ -729,11 +687,9 @@ public static function getAnchorTag($url, $title = '', $encodeTitle = true, $isU
     /**
      * Generates the attributes for an anchor tag from given URL.
      *
-     * @param string $url
-     * @param bool $isUgc true to add rel=ugc to the attributes
      * @since       5.3
      */
-    public static function getAnchorTagAttributes($url, $isUgc = false): string
+    public static function getAnchorTagAttributes(string $url, bool $isUgc = false): string
     {
         $external = true;
         if (ApplicationHandler::getInstance()->isInternalURL($url)) {
@@ -761,24 +717,16 @@ public static function getAnchorTagAttributes($url, $isUgc = false): string
 
     /**
      * Splits given string into smaller chunks.
-     *
-     * @param string $string
-     * @param int $length
-     * @param string $break
      */
-    public static function splitIntoChunks($string, $length = 75, $break = "\r\n"): string
+    public static function splitIntoChunks(string $string, int $length = 75, string $break = "\r\n"): string
     {
         return \mb_ereg_replace('.{' . $length . '}', "\\0" . $break, $string);
     }
 
     /**
      * Simple multi-byte safe wordwrap() function.
-     *
-     * @param string $string
-     * @param int $width
-     * @param string $break
      */
-    public static function wordwrap($string, $width = 50, $break = ' '): string
+    public static function wordwrap(string $string, int $width = 50, string $break = ' '): string
     {
         $result = '';
         $substrings = \explode($break, $string);
@@ -811,10 +759,8 @@ public static function wordwrap($string, $width = 50, $break = ' '): string
 
     /**
      * Shortens numbers larger than 1000 by using unit suffixes.
-     *
-     * @param int $number
      */
-    public static function getShortUnit($number): string
+    public static function getShortUnit(int $number): string
     {
         $unitSuffix = '';
 
@@ -844,10 +790,9 @@ public static function getShortUnit($number): string
      * that the separator is just a comma, not a combination of whitespace and
      * a comma.
      *
-     * @param string $string
      * @since   3.1
      */
-    public static function normalizeCsv($string): string
+    public static function normalizeCsv(string $string): string
     {
         return \implode(',', ArrayUtil::trim(\explode(',', $string)));
     }
diff --git a/wcfsetup/install/files/lib/util/Url.class.php b/wcfsetup/install/files/lib/util/Url.class.php
index f9d387e2f9c..8c6cecc54ab 100644
--- a/wcfsetup/install/files/lib/util/Url.class.php
+++ b/wcfsetup/install/files/lib/util/Url.class.php
@@ -24,6 +24,7 @@
  *  query: string,
  *  fragment: string,
  * }
+ * @implements \ArrayAccess<int|string, int|string>
  */
 final class Url implements \ArrayAccess
 {
@@ -125,7 +126,7 @@ public function offsetExists(mixed $offset): bool
     }
 
     #[\Override]
-    public function offsetGet(mixed $offset): mixed
+    public function offsetGet(mixed $offset): int|string
     {
         return $this->components[$this->getIndex($offset)];
     }
diff --git a/wcfsetup/install/files/lib/util/UserAgent.class.php b/wcfsetup/install/files/lib/util/UserAgent.class.php
index 132faefeaec..82ca71b5943 100644
--- a/wcfsetup/install/files/lib/util/UserAgent.class.php
+++ b/wcfsetup/install/files/lib/util/UserAgent.class.php
@@ -30,6 +30,8 @@ public function __construct(string $userAgent)
 
     /**
      * Detects the browser on the basis of the user agent.
+     *
+     * @return array{0: string, 1: string}|array{0: null, 1: null}
      */
     private function detectBrowser(string $userAgent): array
     {
diff --git a/wcfsetup/install/files/lib/util/UserUtil.class.php b/wcfsetup/install/files/lib/util/UserUtil.class.php
index 9cba61d9fa7..6fc505dd72e 100644
--- a/wcfsetup/install/files/lib/util/UserUtil.class.php
+++ b/wcfsetup/install/files/lib/util/UserUtil.class.php
@@ -57,7 +57,7 @@ public static function isValidUsername(string $name): bool
     /**
      * @deprecated 5.5 Check whether `User::getUserByUsername()->userID` is falsy.
      */
-    public static function isAvailableUsername($name): bool
+    public static function isAvailableUsername(string $name): bool
     {
         $sql = "SELECT  COUNT(username)
                 FROM    wcf1_user
@@ -65,7 +65,7 @@ public static function isAvailableUsername($name): bool
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$name]);
 
-        return $statement->fetchSingleColumn() == 0;
+        return $statement->fetchSingleColumn() === 0;
     }
 
     /**
@@ -91,7 +91,7 @@ public static function isValidEmail(string $email): bool
     /**
      * @deprecated 5.5 Check whether `User::getUserByEmail()->userID` is falsy.
      */
-    public static function isAvailableEmail($email): bool
+    public static function isAvailableEmail(string $email): bool
     {
         $sql = "SELECT  COUNT(email)
                 FROM    wcf1_user
@@ -99,7 +99,7 @@ public static function isAvailableEmail($email): bool
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([$email]);
 
-        return $statement->fetchSingleColumn() == 0;
+        return $statement->fetchSingleColumn() === 0;
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/util/XML.class.php b/wcfsetup/install/files/lib/util/XML.class.php
index c2d8e0f81c1..612be86943b 100644
--- a/wcfsetup/install/files/lib/util/XML.class.php
+++ b/wcfsetup/install/files/lib/util/XML.class.php
@@ -51,7 +51,7 @@ public function __construct()
      * Loads a xml file for processing.
      *
      * @param string $path
-     * @throws  SystemException
+     * @return void
      */
     public function load($path)
     {
@@ -81,6 +81,7 @@ public function load($path)
      *
      * @param string $path
      * @param string $xml
+     * @return void
      */
     public function loadXML($path, $xml)
     {
@@ -103,6 +104,7 @@ public function loadXML($path, $xml)
     /**
      * Validate the loaded document against the specified xml schema definition.
      *
+     * @return void
      * @deprecated  since 5.2
      */
     public function validate()
@@ -123,6 +125,7 @@ public function validate()
     /**
      * Determines schema for given document.
      *
+     * @return void
      * @deprecated  since 5.2
      */
     protected function getSchema()
@@ -210,7 +213,8 @@ public function pollErrors()
      * Throws a SystemException providing details on xml errors if applicable.
      *
      * @param string $message
-     * @param array $errors
+     * @param array{line: int, message: string}[] $errors
+     * @return never
      * @throws  SystemException
      */
     protected function throwException($message, array $errors = [])
@@ -244,6 +248,7 @@ public function getDocument()
      *
      * @param string $fileLocation location of file
      * @param bool $cdata indicates of values are escaped using cdata
+     * @return void
      * @since   5.2
      */
     public function write($fileLocation, $cdata = false)
@@ -275,6 +280,7 @@ public function write($fileLocation, $cdata = false)
      * @param XMLWriter $writer xml writer
      * @param \DOMElement $element written element
      * @param bool $cdata indicates if element value is escaped using cdata
+     * @return void
      * @since   5.2
      */
     protected function writeElement(XMLWriter $writer, \DOMElement $element, $cdata)
@@ -305,7 +311,7 @@ protected function writeElement(XMLWriter $writer, \DOMElement $element, $cdata)
      * (with the attribute names as array keys).
      *
      * @param \DOMElement $element elements whose attributes will be returned
-     * @return  array               attributes
+     * @return array<string, string> attributes
      * @since   5.2
      */
     public function getAttributes(\DOMElement $element)
diff --git a/wcfsetup/install/files/lib/util/XMLWriter.class.php b/wcfsetup/install/files/lib/util/XMLWriter.class.php
index 7f006471fd6..089eca04b82 100644
--- a/wcfsetup/install/files/lib/util/XMLWriter.class.php
+++ b/wcfsetup/install/files/lib/util/XMLWriter.class.php
@@ -38,7 +38,7 @@ class XMLWriter
      * @param string $namespace
      * @param string $schemaLocation
      * @param string[] $attributes
-     * @throws  SystemException
+     * @return void
      */
     public function beginDocument($rootElement, $namespace, $schemaLocation, array $attributes = [])
     {
@@ -77,7 +77,7 @@ public function beginDocument($rootElement, $namespace, $schemaLocation, array $
      * elements will be automatically closed before flushing.
      *
      * @param string $filename
-     * @return  mixed
+     * @return string|int|void
      */
     public function endDocument($filename = '')
     {
@@ -103,6 +103,7 @@ public function endDocument($filename = '')
      *
      * @param string $element
      * @param string[] $attributes
+     * @return void
      */
     public function startElement($element, array $attributes = [])
     {
@@ -116,6 +117,8 @@ public function startElement($element, array $attributes = [])
 
     /**
      * Ends the last opened element.
+     *
+     * @return void
      */
     public function endElement()
     {
@@ -132,6 +135,8 @@ public function endElement()
      * @param string $cdata
      * @param string[] $attributes
      * @param bool $writeAsCdata
+     *
+     * @return void
      */
     public function writeElement($element, $cdata, array $attributes = [], $writeAsCdata = true)
     {
@@ -158,6 +163,7 @@ public function writeElement($element, $cdata, array $attributes = [], $writeAsC
      * Writes a comment.
      *
      * @param string $comment
+     * @return void
      * @since   5.2
      */
     public function writeComment($comment)
@@ -170,6 +176,7 @@ public function writeComment($comment)
      *
      * @param string $attribute
      * @param string $value
+     * @return void
      */
     public function writeAttribute($attribute, $value)
     {
@@ -180,6 +187,7 @@ public function writeAttribute($attribute, $value)
      * Writes a list of attributes to last opened element.
      *
      * @param string[] $attributes
+     * @return void
      */
     public function writeAttributes(array $attributes)
     {
diff --git a/wcfsetup/install/files/lib/util/exception/CryptoException.class.php b/wcfsetup/install/files/lib/util/exception/CryptoException.class.php
index 6d5d9ab2d32..7c0f6cc4aef 100644
--- a/wcfsetup/install/files/lib/util/exception/CryptoException.class.php
+++ b/wcfsetup/install/files/lib/util/exception/CryptoException.class.php
@@ -13,7 +13,8 @@
 class CryptoException extends \Exception
 {
     /**
-     * @inheritDoc
+     * @param string $message
+     * @param ?\Throwable $previous
      */
     public function __construct($message, $previous = null)
     {
diff --git a/wcfsetup/install/files/proxy_sourcemap.php b/wcfsetup/install/files/proxy_sourcemap.php
index cfe5323a79a..8bde570a223 100644
--- a/wcfsetup/install/files/proxy_sourcemap.php
+++ b/wcfsetup/install/files/proxy_sourcemap.php
@@ -58,7 +58,7 @@ function verifySignature(string $map, string $signature): bool
  * Returns a string if a map name could be extracted. Returns a class implementing
  * ResponseInterface if the $query is invalid.
  */
-function getMapFromQuery(string $query)
+function getMapFromQuery(string $query): string|ResponseInterface
 {
     try {
         // Step 1: Extract the signature and map name.