feat(message-list): add unified folder support

feature/mail/message/list/api/src/debug/kotlin/net/thunderbird/feature/mail/message/list/ui/component/organism/NewMessageItemPreview.kt

@@ -161,6 +161,7 @@ private fun PreviewDefault(
             state = MessageItemUi(
                 state = MessageItemUi.State.New,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -209,6 +210,7 @@ private fun PreviewCompact(
             state = MessageItemUi(
                 state = MessageItemUi.State.New,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -257,6 +259,7 @@ private fun PreviewRelaxed(
             state = MessageItemUi(
                 state = MessageItemUi.State.New,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -305,6 +308,7 @@ private fun PreviewDefaultWithoutAccountIndicator(
             state = MessageItemUi(
                 state = MessageItemUi.State.New,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,

feature/mail/message/list/api/src/debug/kotlin/net/thunderbird/feature/mail/message/list/ui/component/organism/ReadMessageItemPreview.kt

@@ -192,6 +192,7 @@ private fun PreviewDefault(
             state = MessageItemUi(
                 state = MessageItemUi.State.Read,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -240,6 +241,7 @@ private fun PreviewCompact(
             state = MessageItemUi(
                 state = MessageItemUi.State.Read,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -288,6 +290,7 @@ private fun PreviewRelaxed(
             state = MessageItemUi(
                 state = MessageItemUi.State.Read,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -336,6 +339,7 @@ private fun PreviewDefaultWithoutAccountIndicator(
             state = MessageItemUi(
                 state = MessageItemUi.State.Read,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,

feature/mail/message/list/api/src/debug/kotlin/net/thunderbird/feature/mail/message/list/ui/component/organism/UnreadMessageItemPreview.kt

@@ -161,6 +161,7 @@ private fun PreviewDefault(
             state = MessageItemUi(
                 state = MessageItemUi.State.Unread,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -209,6 +210,7 @@ private fun PreviewCompact(
             state = MessageItemUi(
                 state = MessageItemUi.State.Unread,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -257,6 +259,7 @@ private fun PreviewRelaxed(
             state = MessageItemUi(
                 state = MessageItemUi.State.Unread,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,
@@ -305,6 +308,7 @@ private fun PreviewDefaultWithoutIndicator(
             state = MessageItemUi(
                 state = MessageItemUi.State.Unread,
                 id = "",
+                messageReference = "reference",
                 account = Account(id = AccountIdFactory.create(), color = params.accountColor),
                 senders = ComposedAddressUi(
                     displayName = params.sender,

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/MessageListContract.kt

@@ -12,6 +12,7 @@ import net.thunderbird.feature.mail.message.list.ui.component.MessageListScope
 import net.thunderbird.feature.mail.message.list.ui.component.rememberMessageListScope
 import net.thunderbird.feature.mail.message.list.ui.effect.MessageListEffect
 import net.thunderbird.feature.mail.message.list.ui.event.MessageListEvent
+import net.thunderbird.feature.mail.message.list.ui.legacy.LegacyMessageListBridge
 import net.thunderbird.feature.mail.message.list.ui.state.MessageListState
 import net.thunderbird.feature.mail.message.list.ui.state.sideeffect.MessageListStateSideEffectHandlerFactory
 import net.thunderbird.feature.notification.api.content.InAppNotification
@@ -48,6 +49,8 @@ interface MessageListContract {
         data class Args(
             val accountIds: Set<AccountId>,
             val folderId: Long?,
+            // Temporary argument just to allow using the current legacy implementation.
+            val legacyMessageListBridge: LegacyMessageListBridge,
         )
     }
 

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/effect/MessageListEffect.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.feature.mail.message.list.ui.effect
 
 import net.thunderbird.feature.account.AccountId
+import net.thunderbird.feature.mail.message.list.ui.state.MessageItemUi
 import net.thunderbird.feature.mail.message.list.ui.state.MessageListState
 
 /**
@@ -81,4 +82,22 @@ sealed interface MessageListEffect {
      * that have been discarded for that account.
      */
     data class DraftsDiscarded(val messagesIdByAccountId: Map<AccountId, List<Long>>) : MessageListEffect
+
+    /**
+     * Effect to update the state and appearance of the contextual action mode toolbar.
+     *
+     * @param title The text to be displayed in the action mode toolbar, usually indicating
+     * the number of currently selected messages.
+     * @param isAllSelected Whether all available messages in the current list are selected.
+     */
+    data class UpdateToolbarActionMode(
+        val title: String,
+        val isAllSelected: Boolean,
+    ) : MessageListEffect
+
+    data object ResetToolbarActionMode : MessageListEffect
+
+    data class ScrollToMessage(val message: MessageItemUi) : MessageListEffect
+
+    data class OpenMessage(val message: MessageItemUi) : MessageListEffect
 }

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/event/MessageItemEvent.kt

@@ -17,6 +17,9 @@ sealed interface MessageItemEvent : MessageListEvent.UserEvent {
      */
     data class OnMessageClick(val message: MessageItemUi) : MessageItemEvent
 
+    data object SelectAll : MessageItemEvent
+    data object DeselectAll : MessageItemEvent
+
     /**
      * Event to toggle the selection state of one or more messages.
      *
@@ -60,4 +63,9 @@ sealed interface MessageItemEvent : MessageListEvent.UserEvent {
      * @property message The message item that was swiped.
      */
     data class OnSwipeMessage(val message: MessageItemUi, val swipeAction: SwipeAction) : MessageItemEvent
+
+    data class OnFocusEnter(val message: MessageItemUi) : MessageItemEvent
+    data class OnFocusExit(val message: MessageItemUi) : MessageItemEvent
+
+    data class SetMessageActive(val message: MessageItemUi?) : MessageItemEvent
 }

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/event/MessageListEvent.kt

@@ -56,7 +56,7 @@ sealed interface MessageListEvent {
      *
      * @param progress A float value between 0.0 and 1.0 representing the loading completion percentage.
      */
-    data class UpdateLoadingProgress(val progress: Float) : SystemEvent
+    data class UpdateLoadingProgress(val progress: Float, val messages: List<MessageItemUi> = emptyList()) : SystemEvent
 
     /**
      * A system event indicating that a list of messages has been successfully loaded.

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/legacy/LegacyMessageListBridge.kt

@@ -0,0 +1,27 @@
+package net.thunderbird.feature.mail.message.list.ui.legacy
+
+import kotlinx.coroutines.flow.Flow
+import net.thunderbird.feature.mail.message.list.preferences.MessageListPreferences
+import net.thunderbird.feature.mail.message.list.ui.state.MessageItemUi
+import net.thunderbird.feature.mail.message.list.ui.state.MessageListMetadata
+
+/**
+ * Bridge interface for accessing functionalities implemented in the legacy message list system.
+ *
+ * @see MessageListPreferences for available display and behavior customization options
+ * @see MessageListMetadata for contextual information about the message list state
+ * @see MessageItemUi for the structure of individual message items in the returned list
+ */
+interface LegacyMessageListBridge {
+    /**
+     * Loads messages for the current mailbox stored in the database.
+     *
+     * @param preferences Display and behaviour settings that influence how messages are loaded.
+     * @param metadata Contextual information about the message list (e.g. folder, account).
+     * @returns a [Flow] that emits updated [MessageItemUi] lists as the underlying data changes.
+     */
+    fun loadMessages(
+        preferences: MessageListPreferences,
+        metadata: MessageListMetadata,
+    ): Flow<List<MessageItemUi>>
+}

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/state/MessageItemUi.kt

@@ -1,6 +1,7 @@
 package net.thunderbird.feature.mail.message.list.ui.state
 
 import androidx.compose.runtime.Immutable
+import kotlinx.collections.immutable.toPersistentList
 
 /**
  * Represents the UI state of a single message item in a message list.
@@ -12,6 +13,7 @@ import androidx.compose.runtime.Immutable
  *
  * @property state The current display state of the message (e.g., Read, Unread, Selected).
  * @property id The unique identifier for the message.
+ * @param messageReference The reference to the message in the underlying data source.
  * @property account The account to which this message belongs.
  * @property senders The composed representation of the message sender(s) with display name,
  *  styling, and avatar.
@@ -32,6 +34,7 @@ import androidx.compose.runtime.Immutable
 data class MessageItemUi(
     val state: State,
     val id: String,
+    val messageReference: String,
     val account: Account,
     val senders: ComposedAddressUi,
     val subject: String,
@@ -63,3 +66,29 @@ data class MessageItemUi(
         Unread,
     }
 }
+
+/**
+ * Create a copy of this message item with the updated [state] and refreshed sender
+ * display name styling.
+ *
+ * @param state The new state to apply.
+ * @return A new [MessageItemUi] instance with the updated state and styling.
+ */
+fun MessageItemUi.withState(state: MessageItemUi.State): MessageItemUi {
+    val styles = buildList {
+        when (val separatorIndex = senders.displayName.indexOf(',')) {
+            -1 if state != MessageItemUi.State.Read -> add(ComposedAddressStyle.Bold(start = 0))
+            in 0..Int.MAX_VALUE if state != MessageItemUi.State.Read -> {
+                add(ComposedAddressStyle.Bold(start = 0, end = separatorIndex))
+                add(ComposedAddressStyle.Regular(start = separatorIndex))
+            }
+
+            else -> add(ComposedAddressStyle.Regular(start = 0))
+        }
+    }.toPersistentList()
+
+    return copy(
+        senders = senders.copy(displayNameStyles = styles),
+        state = state,
+    )
+}

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/state/MessageListMetadata.kt

@@ -31,8 +31,9 @@ data class MessageListMetadata(
     val folder: Folder?,
     val swipeActions: ImmutableMap<AccountId, SwipeActions>,
     val sortCriteriaPerAccount: ImmutableMap<AccountId?, SortCriteria>,
-    val activeMessage: MessageItemUi?,
     val isActive: Boolean,
+    val activeMessage: MessageItemUi? = null,
+    val focusedMessage: MessageItemUi? = null,
     val availablePrimarySortTypes: ImmutableSet<SortType> = SortType.entries.toPersistentSet(),
     val availableSecondarySortTypes: ImmutableSet<SortType> = SortCriteria.DateSortTypeOnly.toPersistentSet(),
     val footer: MessageListFooter = MessageListFooter(),

feature/mail/message/list/api/src/main/kotlin/net/thunderbird/feature/mail/message/list/ui/state/MessageListState.kt

@@ -4,6 +4,7 @@ import androidx.compose.runtime.Immutable
 import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.persistentListOf
 import kotlinx.collections.immutable.persistentMapOf
+import kotlinx.collections.immutable.toImmutableList
 import net.thunderbird.feature.mail.message.list.preferences.MessageListPreferences
 
 /**
@@ -74,6 +75,26 @@ sealed interface MessageListState {
         is WarmingUp -> copy(preferences = preferences?.transform())
     }
 
+    /**
+     * Creates a copy of the current state with an updated list of [messages], preserving all other
+     * properties.
+     *
+     * @param transform A lambda function that receives the current [ImmutableList] of [MessageItemUi]
+     * and returns a new, transformed list.
+     * @return A new [MessageListState] instance of the same type as the original, containing the
+     * transformed messages.
+     */
+    fun mapMessages(transform: (MessageItemUi) -> MessageItemUi): MessageListState {
+        val messages = messages.map(transform).toImmutableList()
+        return when (this) {
+            is LoadedMessages -> copy(messages = messages)
+            is LoadingMessages -> copy(messages = messages)
+            is SearchingMessages -> copy(messages = messages)
+            is SelectingMessages -> copy(messages = messages)
+            is WarmingUp -> copy(messages = messages)
+        }
+    }
+
     /**
      * Represents the initial state of the message list screen before any messages are loaded.
      *

feature/mail/message/list/internal/src/debug/kotlin/net/thunderbird/feature/mail/message/list/internal/ui/preview/MessagePreviewHelper.kt

@@ -42,6 +42,7 @@ internal object MessagePreviewHelper {
         forwarded = forwarded,
         selected = selected,
         threadCount = threadCount,
+        messageReference = "reference",
     )
 
     val sampleMessages = persistentListOf(

feature/mail/message/list/internal/src/main/kotlin/net/thunderbird/feature/mail/message/list/internal/DefaultLocalDeleteOperationDecider.kt

@@ -3,7 +3,7 @@ package net.thunderbird.feature.mail.message.list.internal
 import net.thunderbird.core.android.account.LegacyAccountDto
 import net.thunderbird.feature.mail.message.list.LocalDeleteOperationDecider
 
-class DefaultLocalDeleteOperationDecider : LocalDeleteOperationDecider {
+internal class DefaultLocalDeleteOperationDecider : LocalDeleteOperationDecider {
     override fun isDeleteImmediately(
         account: LegacyAccountDto,
         folderId: Long,

feature/mail/message/list/internal/src/main/kotlin/net/thunderbird/feature/mail/message/list/internal/FeatureMessageListModule.kt

@@ -77,6 +77,7 @@ val featureMessageListModule = module {
             logger = get(),
             messageListStateMachineFactory = get(),
             stateSideEffectHandlersFactories = getList { parameters },
+            stringsResourceManager = get(),
         )
     }
     single<LocalDeleteOperationDecider> { DefaultLocalDeleteOperationDecider() }

feature/mail/message/list/internal/src/main/kotlin/net/thunderbird/feature/mail/message/list/internal/ui/MessageListScreenAccessibilityState.kt

@@ -30,7 +30,7 @@ import net.thunderbird.feature.mail.message.list.R as ApiR
  *  swipe actions are available.
  */
 @Stable
-class MessageListScreenAccessibilityState(
+internal class MessageListScreenAccessibilityState(
     private val stateDescription: Map<MessageListStateDescription, String>,
     val swipeDirectionAccessibilityAction: ImmutableList<SwipeDirectionAccessibilityAction> = persistentListOf(),
 ) {
@@ -97,7 +97,9 @@ enum class MessageListStateDescription {
  *  description strings or swipe actions change.
  */
 @Composable
-fun rememberMessageListScreenAccessibilityState(swipeActions: SwipeActions?): MessageListScreenAccessibilityState {
+internal fun rememberMessageListScreenAccessibilityState(
+    swipeActions: SwipeActions?,
+): MessageListScreenAccessibilityState {
     val stateDescription = mapOf(
         MessageListStateDescription.NewMessage to stringResource(
             id = R.string.message_list_state_new_message_description,