feat: migrate to Symfony Asset Mapper, drop psalm.xml and admin.css

- Add symfony/asset-mapper bundle with importmap and recipe files
- Remove unused psalm.xml (project relies on PHPStan)
- Remove obsolete public/css/admin.css

Carved out of the closed PR #60 dependency-update scope as a focused PR.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: turegjorup

.gitignore

@@ -30,5 +30,11 @@ yarn-error.log
 phpstan.neon
 ###< phpstan/phpstan ###
 .phpunit.cache
+
+###> symfony/asset-mapper ###
+/public/assets/
+/assets/vendor/
+###< symfony/asset-mapper ###
+
 .twig-cs-fixer.cache
 .playwright-mcp

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- [#81](https://github.com/itk-dev/devops_itksites/pull/81) 5564: Asset Mapper migration
+  - Add Symfony Asset Mapper bundle and importmap
+
 ## [1.11.0] - 2026-05-19
 
 - [#78](https://github.com/itk-dev/devops_itksites/pull/78)

assets/app.js

@@ -0,0 +1,9 @@
+/*
+ * Welcome to your app's main JavaScript file!
+ *
+ * This file will be included onto the page via the importmap() Twig function,
+ * which should already be in your base.html.twig.
+ */
+import "./styles/app.css";
+
+console.log("This log comes from assets/app.js - welcome to AssetMapper! 🎉");

assets/styles/app.css

@@ -0,0 +1,28 @@
+:root {
+    --body-max-width: 100%;
+    --sidebar-bg: #fff;
+    /* make the base font size smaller */
+    --button-primary-bg: rgb(0, 123, 166);
+    --pagination-active-bg: rgb(0, 123, 166);
+    --link-color: rgb(0, 123, 166);
+    --sidebar-menu-active-item-color: rgb(0, 123, 166);
+    --badge-boolean-true-bg: rgb(0, 123, 166);
+    --badge-boolean-false-bg: rgb(228, 73, 48);
+    --badge-boolean-false-color: var(--white);
+    --sidebar-menu-color: rgb(66, 66, 66);
+    --text-color-dark: rgb(66, 66, 66);
+    --bs-danger-rgb: 228, 73, 48;
+}
+
+/* Grouped dropdown group styling for index pages */
+.dropdown-menu {
+    .btn-danger i,
+    .text-danger i {
+        color: var(--button-invisible-danger-color);
+    }
+
+    a.btn-danger:hover,
+    a.text-danger:hover {
+        background: var(--button-invisible-danger-hover-hover-bg);
+    }
+}

composer.json

@@ -21,6 +21,7 @@
         "phpstan/phpdoc-parser": "^2.0",
         "symfony/amqp-messenger": "^8.0",
         "symfony/asset": "^8.0",
+        "symfony/asset-mapper": "~8.0.0",
         "symfony/browser-kit": "^8.0",
         "symfony/console": "^8.0",
         "symfony/doctrine-messenger": "^8.0",
@@ -111,7 +112,8 @@
         ],
         "auto-scripts": {
             "cache:clear": "symfony-cmd",
-            "assets:install %PUBLIC_DIR%": "symfony-cmd"
+            "assets:install %PUBLIC_DIR%": "symfony-cmd",
+            "importmap:install": "symfony-cmd"
         },
         "coding-standards-apply": [
             "vendor/bin/php-cs-fixer fix"

composer.lock

@@ -0,0 +1,11 @@
+framework:
+    asset_mapper:
+        # The paths to make available to the asset mapper.
+        paths:
+            - assets/
+        missing_import_mode: strict
+
+when@prod:
+    framework:
+        asset_mapper:
+            missing_import_mode: warn

config/packages/asset_mapper.yaml

@@ -280,7 +280,7 @@
  *         }>,
  *     },
  *     asset_mapper?: bool|array{ // Asset Mapper configuration
- *         enabled?: bool|Param, // Default: false
+ *         enabled?: bool|Param, // Default: true
  *         paths?: string|array<string, scalar|Param|null>,
  *         excluded_patterns?: list<scalar|Param|null>,
  *         exclude_dotfiles?: bool|Param, // If true, any files starting with "." will be excluded from the asset mapper. // Default: true

config/reference.php

@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * Returns the importmap for this application.
+ *
+ * - "path" is a path inside the asset mapper system. Use the
+ *     "debug:asset-map" command to see the full list of paths.
+ *
+ * - "entrypoint" (JavaScript only) set to true for any module that will
+ *     be used as an "entrypoint" (and passed to the importmap() Twig function).
+ *
+ * The "importmap:require" command can be used to add new entries to this file.
+ */
+return [
+    'app' => [
+        'path' => './assets/app.js',
+        'entrypoint' => true,
+    ],
+];