Clean obsolete Extentions during client synchronization

Include the prepared cleanup of both client roots while preserving manifest-listed files and unrelated user state. Verified on Windows through FVM: full formatting and analysis, all 76 tests, production dry run, x64 build and DSA signature verification.

AGENTS.md

@@ -96,6 +96,8 @@ or local-only API URLs.
 - The server manifest is the source of truth for client files.
 - Sync removes files absent from the manifest under `Data` and `WoW/Data`,
   plus legacy `WoW.exe` and DLLs directly in the installation root or `WoW`.
+  Also clean obsolete `Extentions` directories in either client root and remove
+  the directory itself when no manifest files require it.
   Remove unused Data subdirectories only after their children, without recursive
   deletion. Preserve unrelated files and user state outside these areas.
 - Language archives under `Data/ruRU` or `WoW/Data/ruRU` use the regular manifest sync.

README.md

@@ -28,6 +28,8 @@ During synchronization, the manifest is authoritative for `Data/` and
 Legacy `WoW.exe` and DLLs in the installation root or `WoW/` are also removed
 when absent from the manifest. Required DLLs stay; player settings, addons,
 logs, screenshots, and other files outside these cleanup areas are preserved.
+The obsolete `Extentions/` directory in either client root is cleaned the same
+way and removed when no manifest files require it.
 Cleanup runs even when all manifest files are already up to date.
 
 ## Stack

docs/launcher_web_api_spec.md

@@ -173,6 +173,9 @@ to the selected installation root, including files in nested directories.
 The scan separately collects stale paths without hashing their contents:
 
 - every file absent from the manifest in `Data/` and `WoW/Data/`
+- every file absent from the manifest in obsolete `Extentions/` and
+  `WoW/Extentions/` directories, including unused subdirectories and the
+  Extentions directory itself when no manifest files require it
 - `WoW.exe` and `*.dll` absent from the manifest directly in the installation
   root or `WoW/` (binary names are matched without case sensitivity)
 - unused Data subdirectories, ordered after their children; the Data roots and
@@ -325,7 +328,8 @@ The automated tests cover:
 - deterministic `buildHash`
 - path normalization used by `buildHash`
 - preservation of user state and unrelated unmanaged files during cleanup
-- removal of unmanaged Data files, unused subdirectories, WoW.exe, and DLLs
+- removal of unmanaged Data files, unused subdirectories, WoW.exe, DLLs, and
+  obsolete Extentions directories
 - preservation of manifest-listed DLLs and WoW.exe
 - cache cleanup behavior
 - safe path resolution

lib/features/launcher/data/game_installation_service.dart

@@ -630,11 +630,11 @@ Future<List<String>> _collectStalePaths(
   String relativePath(FileSystemEntity entity) =>
       normalizeClientPath(p.relative(entity.path, from: rootDirectory.path));
 
-  Future<void> collectData(Directory directory) async {
+  Future<void> collectStaleDirectory(Directory directory) async {
     await for (final entity in directory.list(followLinks: false)) {
       final path = relativePath(entity);
       if (entity is Directory) {
-        await collectData(entity);
+        await collectStaleDirectory(entity);
         if (!manifestDirectories.contains(pathKey(path))) {
           stalePaths.add(path);
         }
@@ -653,12 +653,20 @@ Future<List<String>> _collectStalePaths(
       final name = p.basename(entity.path).toLowerCase();
       if (entity is Directory) {
         if (name == 'data') {
-          await collectData(entity);
+          await collectStaleDirectory(entity);
+        } else if (name == 'extentions') {
+          await collectStaleDirectory(entity);
+          if (!manifestDirectories.contains(pathKey(relativePath(entity)))) {
+            stalePaths.add(relativePath(entity));
+          }
         } else if (!nested && name == 'wow') {
           await collectClientRoot(entity, nested: true);
         }
-      } else if ((name == 'wow.exe' || name.endsWith('.dll')) &&
-          !manifestPaths.contains(pathKey(relativePath(entity)))) {
+      } else if ((name == 'wow.exe' ||
+              name.endsWith('.dll') ||
+              (entity is Link && name == 'extentions')) &&
+          !manifestPaths.contains(pathKey(relativePath(entity))) &&
+          !manifestDirectories.contains(pathKey(relativePath(entity)))) {
         stalePaths.add(relativePath(entity));
       }
     }

test/features/launcher/application/client_sync_use_case_test.dart

@@ -169,7 +169,12 @@ void main() {
       addTearDown(() => root.delete(recursive: true));
       final service = GameInstallationService();
       final retained = ['MoonWell.exe', 'Data/common.MPQ', 'required.dll'];
-      final obsolete = ['Data/old/patch.MPQ', 'WoW.exe', 'unused.DLL'];
+      final obsolete = [
+        'Data/old/patch.MPQ',
+        'WoW.exe',
+        'unused.DLL',
+        'Extentions/bin/extension.dll',
+      ];
       for (final path in [
         ...retained,
         ...obsolete,
@@ -217,7 +222,12 @@ void main() {
         contains(ClientSyncStage.removingStaleFiles),
       );
       expect(api.downloadedPaths, isEmpty);
-      for (final path in [...obsolete, 'Data/old']) {
+      for (final path in [
+        ...obsolete,
+        'Data/old',
+        'Extentions/bin',
+        'Extentions',
+      ]) {
         expect(
           await FileSystemEntity.type(
             service.resolveClientPath(root.path, path),

test/features/launcher/data/game_installation_service_test.dart

@@ -77,6 +77,8 @@ void main() {
           'WoW/WoW.exe',
           'WoW/old.dll',
           'WoW/Data/old.MPQ',
+          'Extentions/bin/extension.dll',
+          'WoW/Extentions/old.txt',
         ];
         final untouchedPaths = [
           'Cache/cache.bin',
@@ -105,6 +107,9 @@ void main() {
         await Directory(
           service.resolveClientPath(rootDirectory.path, 'Data/unused/nested'),
         ).create(recursive: true);
+        await Directory(
+          service.resolveClientPath(rootDirectory.path, 'Extentions/empty'),
+        ).create(recursive: true);
         final manifest = await _manifestForPaths(
           service,
           rootDirectory,
@@ -129,6 +134,10 @@ void main() {
             'Data/empty',
             'Data/unused/nested',
             'Data/unused',
+            'Extentions/bin',
+            'Extentions/empty',
+            'Extentions',
+            'WoW/Extentions',
           ]),
         );
         for (final path in snapshot.stalePaths) {