refactor: share future coalescing, Plex client access, and event helpers

Deduplicates the hand-rolled coalescing/caching maps, the Plex client cast,
the missing-serverId event guard and the progress-failure backoff, and drops
the MusicPlaybackService availability gate, which could never fail in
production.

lib/screens/libraries/tabs/library_browse_tab.dart

@@ -41,7 +41,6 @@ import '../../../widgets/media_card_list_layout.dart';
 import '../../../widgets/bottom_sheet_page_scaffold.dart';
 import '../../../widgets/overlay_sheet.dart';
 import '../../../mixins/library_tab_focus_mixin.dart';
-import '../../../services/plex_client.dart';
 import '../folder_tree_view.dart';
 import '../filters_bottom_sheet.dart';
 import '../sort_bottom_sheet.dart';
@@ -1030,8 +1029,8 @@ class _LibraryBrowseTabState extends BaseLibraryTabState<MediaItem, LibraryBrows
   Future<List<MediaFilterValue>> _loadFilterValues(MediaFilter filter) async {
     if (!mounted) return const [];
 
-    final client = context.tryGetMediaClientForServer(serverIdOrNull(widget.library.serverId));
-    if (client is PlexClient) return client.getFilterValues(filter.key);
+    final client = context.tryGetPlexClientForServer(serverIdOrNull(widget.library.serverId));
+    if (client != null) return client.getFilterValues(filter.key);
 
     // Jellyfin's canonical filter values come from the cached `/Items/Filters`
     // payload. If that payload missed a category, there is no neutral endpoint

lib/screens/music/artist_detail_screen.dart

@@ -74,8 +74,7 @@ class _ArtistDetailScreenState extends BaseMediaListDetailScreen<ArtistDetailScr
   }
 
   /// Plays the artist's full track list. The tracks aren't part of the album
-  /// listing this screen loads, so this costs one extra server round-trip —
-  /// gated on playback availability first so the stub never fetches.
+  /// listing this screen loads, so this costs one extra server round-trip.
   Future<void> _playAll({bool shuffle = false}) async {
     await playFetchedTracks(
       context,

lib/services/music/music_playback_service.dart

@@ -38,10 +38,6 @@ class MusicPlayContext {
 /// discrete changes (track, status, queue shape, modes) — progress bars
 /// subscribe to [positionStream] instead.
 abstract class MusicPlaybackService extends ChangeNotifier {
-  /// False on the stub — playback affordances should render disabled or
-  /// fall back to a "not supported yet" notice.
-  bool get isAvailable;
-
   MediaItem? get currentTrack;
   MusicPlaybackStatus get status;
   bool get isPlaying => status == MusicPlaybackStatus.playing;
@@ -158,8 +154,6 @@ class StubMusicPlaybackService extends MusicPlaybackService {
   final ValueNotifier<double> _volumeNotifier = ValueNotifier<double>(100);
   int _playIntentGeneration = 0;
   int _queueSessionRevision = 0;
-  @override
-  bool get isAvailable => false;
 
   @override
   MediaItem? get currentTrack => null;

lib/services/music/music_playback_service_impl.dart

@@ -169,9 +169,6 @@ class MusicPlaybackServiceImpl extends MusicPlaybackService with WidgetsBindingO
   // Getters
   // ---------------------------------------------------------------------
 
-  @override
-  bool get isAvailable => true;
-
   @override
   MediaItem? get currentTrack => _currentTrack;
 

lib/services/playback_progress_tracker.dart

@@ -255,27 +255,14 @@ class PlaybackProgressTracker {
                 }
               })
               .catchError((Object e) {
-                _consecutiveFailures++;
-                // Exponential backoff: skip 1, 2, 4, 8... ticks (capped at 6 ≈ 60s)
-                _ticksToSkip = (1 << (_consecutiveFailures - 1)).clamp(1, 6);
-                appLogger.d(
-                  'Progress update failed ($_consecutiveFailures consecutive), '
-                  'skipping next $_ticksToSkip tick(s)',
-                  error: e,
-                );
+                _recordProgressFailure(e);
                 unawaited(_queueOnlineFailureProgress(position, duration));
               }),
         );
       }
     } catch (e) {
       if (!isOffline) {
-        _consecutiveFailures++;
-        _ticksToSkip = (1 << (_consecutiveFailures - 1)).clamp(1, 6);
-        appLogger.d(
-          'Progress update failed ($_consecutiveFailures consecutive), '
-          'skipping next $_ticksToSkip tick(s)',
-          error: e,
-        );
+        _recordProgressFailure(e);
         await _queueOnlineFailureProgress(
           attemptedPosition ?? player.state.position,
           attemptedDuration ?? player.state.duration,
@@ -303,6 +290,17 @@ class PlaybackProgressTracker {
     }
   }
 
+  void _recordProgressFailure(Object e) {
+    _consecutiveFailures++;
+    // Exponential backoff: skip 1, 2, 4, 8... ticks (capped at 6 ≈ 60s)
+    _ticksToSkip = (1 << (_consecutiveFailures - 1)).clamp(1, 6);
+    appLogger.d(
+      'Progress update failed ($_consecutiveFailures consecutive), '
+      'skipping next $_ticksToSkip tick(s)',
+      error: e,
+    );
+  }
+
   void _resetBackoff() {
     if (_consecutiveFailures > 0) {
       _consecutiveFailures = 0;

lib/services/trackers/anime_episode_progress_resolver.dart

@@ -3,6 +3,7 @@ import '../../media/media_kind.dart';
 import '../../media/media_server_client.dart';
 import '../../models/trackers/anime_lists_mapping.dart';
 import '../../utils/app_logger.dart';
+import 'future_coalescer.dart';
 
 enum AnimeProgressScope { show, season, mapped }
 
@@ -30,7 +31,7 @@ abstract interface class AnimeEpisodeProgressLookup {
 
 class AnimeEpisodeProgressResolver implements AnimeEpisodeProgressLookup {
   final MediaServerClient _client;
-  final Map<String, Future<Map<int, _SeasonProgress>?>> _seasonProgressLoads = {};
+  final KeyedFutureCoalescer<String, Map<int, _SeasonProgress>?> _seasonProgressLoads = KeyedFutureCoalescer();
 
   AnimeEpisodeProgressResolver(this._client);
 
@@ -61,7 +62,7 @@ class AnimeEpisodeProgressResolver implements AnimeEpisodeProgressLookup {
       return includeCurrentEpisode ? ResolvedAnimeProgress(progress: animeMatch.anidbEpisode) : null;
     }
 
-    final progressBySeason = await _seasonProgressFor(showId);
+    final progressBySeason = await _seasonProgressLoads.run(showId, () => _loadSeasonProgress(showId));
     if (progressBySeason == null) return null;
 
     final currentAlreadyWatched = (episode.viewCount ?? 0) > 0 || !includeCurrentEpisode;
@@ -97,20 +98,6 @@ class AnimeEpisodeProgressResolver implements AnimeEpisodeProgressLookup {
     }
   }
 
-  Future<Map<int, _SeasonProgress>?> _seasonProgressFor(String showId) async {
-    final existing = _seasonProgressLoads[showId];
-    if (existing != null) return existing;
-
-    late final Future<Map<int, _SeasonProgress>?> loading;
-    loading = _loadSeasonProgress(showId).whenComplete(() {
-      if (identical(_seasonProgressLoads[showId], loading)) {
-        final _ = _seasonProgressLoads.remove(showId);
-      }
-    });
-    _seasonProgressLoads[showId] = loading;
-    return loading;
-  }
-
   ResolvedAnimeProgress? _showProgress(Map<int, _SeasonProgress> seasons, bool currentAlreadyWatched) {
     if (seasons.isEmpty) return null;
     var watched = 0;

lib/services/trackers/anime_list_tracker_base.dart

@@ -1,12 +1,13 @@
 import '../../models/trackers/anime_ids.dart';
 import '../../models/trackers/tracker_context.dart';
 import '../../utils/app_logger.dart';
+import 'future_coalescer.dart';
 import 'tracker.dart';
 import 'tracker_id_resolver.dart';
 
 mixin AnimeListTrackerBase<TClient extends DisposableTrackerClient> on TrackerBase, ClientBackedTracker<TClient>
     implements TrackerRatingSource {
-  final Map<int, Future<int?>> _episodeCountLoads = {};
+  final KeyedFutureCache<int, int?> _episodeCountLoads = KeyedFutureCache();
 
   @override
   bool get needsFribb => true;
@@ -83,19 +84,11 @@ mixin AnimeListTrackerBase<TClient extends DisposableTrackerClient> on TrackerBa
     return (activeClient, id);
   }
 
-  Future<int?> _episodeCount(TClient activeClient, int id) {
-    final existing = _episodeCountLoads[id];
-    if (existing != null) return existing;
-
-    late final Future<int?> loading;
-    loading = loadAnimeEpisodeCount(activeClient, id).catchError((Object e) {
-      if (identical(_episodeCountLoads[id], loading)) {
-        final _ = _episodeCountLoads.remove(id);
-      }
-      appLogger.d('$logLabel: failed to fetch anime episode count ($name=$id)', error: e);
-      return null;
-    });
-    _episodeCountLoads[id] = loading;
-    return loading;
-  }
+  Future<int?> _episodeCount(TClient activeClient, int id) => _episodeCountLoads
+      .run(
+        id,
+        () => loadAnimeEpisodeCount(activeClient, id),
+        onError: (e) => appLogger.d('$logLabel: failed to fetch anime episode count ($name=$id)', error: e),
+      )
+      .catchError((Object _) => null);
 }

lib/services/trackers/future_coalescer.dart

@@ -38,4 +38,35 @@ class KeyedFutureCoalescer<K, T> {
     _inFlight[key] = future;
     return future;
   }
+
+  /// Detach every in-flight future — the keyed form of [FutureCoalescer.reset].
+  void clear() {
+    _inFlight.clear();
+  }
+}
+
+/// Keyed cache of loads: like [KeyedFutureCoalescer], but a successful future
+/// stays memoized instead of being dropped on completion, and only a failure
+/// evicts the key so the next call retries. [onError] fires once per failed
+/// load, before the error is rethrown to every caller.
+class KeyedFutureCache<K, T> {
+  final Map<K, Future<T>> _entries = {};
+
+  Future<T> run(K key, Future<T> Function() create, {void Function(Object error)? onError}) {
+    final existing = _entries[key];
+    if (existing != null) return existing;
+
+    late final Future<T> future;
+    future = create().catchError((Object e) {
+      if (identical(_entries[key], future)) _entries.remove(key);
+      onError?.call(e);
+      throw e;
+    });
+    _entries[key] = future;
+    return future;
+  }
+
+  void clear() {
+    _entries.clear();
+  }
 }

lib/services/trackers/tracker_id_resolver.dart

@@ -8,6 +8,7 @@ import '../../utils/external_ids.dart';
 import 'anime_episode_progress_resolver.dart';
 import 'anime_lists_mapping_store.dart';
 import 'fribb_mapping_store.dart';
+import 'future_coalescer.dart';
 
 /// Paired ID output: always-present Plex external IDs (tvdb/imdb/tmdb) plus
 /// optional Fribb-sourced anime IDs (mal/anilist/simkl). Simkl uses [external]
@@ -77,7 +78,7 @@ class TrackerIdResolver {
   /// Null entries mean "the server had no IDs" — cached so scrubbing on an
   /// un-matched item doesn't re-hit the server every position update.
   final Map<String, TrackerIds?> _cache = {};
-  final Map<String, Future<ExternalIds>> _externalIdLoads = {};
+  final KeyedFutureCache<String, ExternalIds> _externalIdLoads = KeyedFutureCache();
 
   TrackerIdResolver(
     MediaServerClient client, {
@@ -97,19 +98,8 @@ class TrackerIdResolver {
   /// [MediaServerClient.fetchExternalIds] surface — Plex hits
   /// `/library/metadata/{id}?includeGuids=1`, Jellyfin reads the inline
   /// `ProviderIds` map.
-  Future<ExternalIds> _fetchExternalIds(String itemId) {
-    final existing = _externalIdLoads[itemId];
-    if (existing != null) return existing;
-    late final Future<ExternalIds> loading;
-    loading = _client.fetchExternalIds(itemId).catchError((Object e) {
-      if (identical(_externalIdLoads[itemId], loading)) {
-        final _ = _externalIdLoads.remove(itemId);
-      }
-      throw e;
-    });
-    _externalIdLoads[itemId] = loading;
-    return loading;
-  }
+  Future<ExternalIds> _fetchExternalIds(String itemId) =>
+      _externalIdLoads.run(itemId, () => _client.fetchExternalIds(itemId));
 
   /// Resolve IDs for a movie.
   Future<TrackerIds?> resolveForMovie(String itemId) async {

lib/utils/deletion_notifier.dart

@@ -4,6 +4,7 @@ import 'app_logger.dart';
 import 'base_notifier.dart';
 import 'global_key_utils.dart';
 import 'hierarchical_event_mixin.dart';
+import 'media_event_keys.dart';
 
 /// Event representing a media item deletion with parent chain for hierarchical invalidation
 class DeletionEvent with HierarchicalEventMixin {
@@ -73,11 +74,8 @@ class DeletionNotifier extends BaseNotifier<DeletionEvent> {
   }
 
   void notifyDeletedItem({required MediaItem item, bool isDownloadOnly = false}) {
-    final serverId = serverIdOrNull(item.serverId);
-    if (serverId == null) {
-      appLogger.w('DeletionNotifier: missing serverId for ${item.id}, skipping deletion event');
-      return;
-    }
+    final serverId = serverIdForEvent(item, notifier: 'DeletionNotifier', event: 'deletion');
+    if (serverId == null) return;
     notify(
       DeletionEvent(
         itemId: item.id,

lib/utils/media_event_keys.dart

@@ -1,5 +1,6 @@
 import '../media/ids.dart';
 import '../media/media_item.dart';
+import 'app_logger.dart';
 import 'global_key_utils.dart';
 
 /// Builds the id filter for a screen showing [items].
@@ -34,3 +35,14 @@ Set<String>? hierarchicalEventGlobalKeys(Iterable<MediaItem> items, {String? fal
   }
   return keys;
 }
+
+/// The [ServerId] an event emitted for [item] should carry, or `null` — after
+/// warning as `<notifier>: … skipping <event> event` — when the item carries
+/// none, since an event without a server id cannot be routed to subscribers.
+ServerId? serverIdForEvent(MediaItem item, {required String notifier, required String event}) {
+  final serverId = serverIdOrNull(item.serverId);
+  if (serverId == null) {
+    appLogger.w('$notifier: missing serverId for ${item.id}, skipping $event event');
+  }
+  return serverId;
+}

lib/utils/music_navigation.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
-import '../i18n/strings.g.dart';
 import '../media/media_item.dart';
 import '../navigation/profile_navigation_scope.dart';
 import '../screens/music/album_detail_screen.dart';
@@ -14,7 +13,6 @@ import '../theme/mono_tokens.dart';
 import 'app_logger.dart';
 import 'platform_detector.dart';
 import 'provider_extensions.dart';
-import 'snackbar_helper.dart';
 
 /// Route name of the now-playing screen — the mini-player's route observer
 /// suppresses itself while this (or the video player) is in the stack.
@@ -90,17 +88,7 @@ void _autoOpenNowPlayingOnTv(BuildContext context) {
   });
 }
 
-/// True when a real music playback engine is bound. On the stub this shows
-/// the standard "not supported yet" notice and returns false — check it
-/// BEFORE fetching tracks so the stub never costs a server round-trip.
-bool ensureMusicPlaybackAvailable(BuildContext context) {
-  if (context.read<MusicPlaybackService>().isAvailable) return true;
-  showAppSnackBar(context, t.messages.musicNotSupported);
-  return false;
-}
-
-/// Start playback of [tracks] via the session [MusicPlaybackService],
-/// surfacing the "not supported yet" notice while the stub is bound.
+/// Start playback of [tracks] via the session [MusicPlaybackService].
 Future<void> playTracks(
   BuildContext context, {
   required List<MediaItem> tracks,
@@ -108,7 +96,6 @@ Future<void> playTracks(
   required MusicPlayContext playContext,
   bool shuffle = false,
 }) async {
-  if (!ensureMusicPlaybackAvailable(context)) return;
   await context.read<MusicPlaybackService>().playFromList(
     tracks: tracks,
     startTrack: startTrack,
@@ -120,9 +107,9 @@ Future<void> playTracks(
 
 /// Fetch a track list with [fetch], then play it — the shape every music
 /// entry point that needs a server round-trip before playback repeats:
-/// availability gate → [MusicPlaybackService.beginPlayIntent] → fetch →
-/// mounted/intent re-check → [playTracks]. Guarding the round-trip with the
-/// intent keeps a slow fetch from replacing a queue the user started later.
+/// [MusicPlaybackService.beginPlayIntent] → fetch → mounted/intent re-check →
+/// [playTracks]. Guarding the round-trip with the intent keeps a slow fetch
+/// from replacing a queue the user started later.
 ///
 /// [onError] reports a failed fetch and runs only while the intent is still
 /// current and [context] mounted; passing null instead lets the failure
@@ -138,7 +125,6 @@ Future<void> playFetchedTracks(
   MediaItem? startTrack,
   bool shuffle = false,
 }) async {
-  if (!ensureMusicPlaybackAvailable(context)) return;
   final service = context.read<MusicPlaybackService>();
   final intent = service.beginPlayIntent();
   final List<MediaItem> tracks;
@@ -167,7 +153,6 @@ Future<void> playFetchedTracks(
 /// must play under the *same* intent as the album fetch, so a stale fallback
 /// can never supersede a newer request.
 Future<void> playTrackWithAlbumContext(BuildContext context, MediaItem track) async {
-  if (!ensureMusicPlaybackAvailable(context)) return;
   final service = context.read<MusicPlaybackService>();
   final intent = service.beginPlayIntent();
 
@@ -206,7 +191,6 @@ Future<void> playTrackWithAlbumContext(BuildContext context, MediaItem track) as
 /// Only call when the seed's server advertises
 /// `ServerCapabilities.instantMix`.
 Future<void> playInstantMix(BuildContext context, MediaItem seed) async {
-  if (!ensureMusicPlaybackAvailable(context)) return;
   await context.read<MusicPlaybackService>().playInstantMix(seed);
   if (context.mounted) _autoOpenNowPlayingOnTv(context);
 }

lib/utils/watch_state_notifier.dart

@@ -5,6 +5,7 @@ import 'app_logger.dart';
 import 'base_notifier.dart';
 import 'global_key_utils.dart';
 import 'hierarchical_event_mixin.dart';
+import 'media_event_keys.dart';
 
 enum WatchStateChangeType { watched, unwatched, progressUpdate, removedFromContinueWatching }
 
@@ -98,11 +99,8 @@ class WatchStateNotifier extends BaseNotifier<WatchStateEvent> {
 
   /// Helper to emit a watched/unwatched event from a [MediaItem].
   void notifyWatched({required MediaItem item, bool isNowWatched = true, String? cacheServerId}) {
-    final serverId = serverIdOrNull(item.serverId);
-    if (serverId == null) {
-      appLogger.w('WatchStateNotifier: missing serverId for ${item.id}, skipping watched event');
-      return;
-    }
+    final serverId = serverIdForEvent(item, notifier: 'WatchStateNotifier', event: 'watched');
+    if (serverId == null) return;
     notify(
       WatchStateEvent(
         itemId: item.id,
@@ -127,11 +125,8 @@ class WatchStateNotifier extends BaseNotifier<WatchStateEvent> {
     String? cacheServerId,
     double watchedThreshold = 0.9,
   }) {
-    final serverId = serverIdOrNull(item.serverId);
-    if (serverId == null) {
-      appLogger.w('WatchStateNotifier: missing serverId for ${item.id}, skipping progress event');
-      return;
-    }
+    final serverId = serverIdForEvent(item, notifier: 'WatchStateNotifier', event: 'progress');
+    if (serverId == null) return;
     final isNowWatched = isWatchedProgress(positionMs: viewOffset, durationMs: duration, threshold: watchedThreshold);
 
     notify(
@@ -151,11 +146,8 @@ class WatchStateNotifier extends BaseNotifier<WatchStateEvent> {
 
   /// Helper to emit a Continue Watching removal event.
   void notifyRemovedFromContinueWatching({required MediaItem item}) {
-    final serverId = serverIdOrNull(item.serverId);
-    if (serverId == null) {
-      appLogger.w('WatchStateNotifier: missing serverId for ${item.id}, skipping continue-watching removal event');
-      return;
-    }
+    final serverId = serverIdForEvent(item, notifier: 'WatchStateNotifier', event: 'continue-watching removal');
+    if (serverId == null) return;
     notify(
       WatchStateEvent(
         itemId: item.id,

lib/widgets/media_context_menu.dart

@@ -296,15 +296,13 @@ class MediaContextMenuState extends State<MediaContextMenu> {
         _MenuAction(value: 'delete', icon: Symbols.delete_rounded, label: t.common.delete, destructive: true),
       );
     } else {
-      // Music (artist/album/track) playback + navigation actions. Play is
-      // always offered — the shared music_navigation helpers surface the
-      // "not supported yet" notice while the stub service is bound. Queue
-      // insertion only exists once a real playback engine is available.
+      // Music (artist/album/track) playback + navigation actions. Queue
+      // insertion only exists where a playback session is bound.
       final isMusicKind = mediaKind != null && mediaKind.isMusic;
       if (isMusicKind) {
         menuActions.add(_MenuAction(value: 'music_play', icon: Symbols.play_arrow_rounded, label: t.common.play));
 
-        final musicAvailable = context.read<MusicPlaybackService?>()?.isAvailable ?? false;
+        final musicAvailable = context.read<MusicPlaybackService?>() != null;
         if (musicAvailable) {
           menuActions.add(
             _MenuAction(value: 'music_play_next', icon: Symbols.playlist_play_rounded, label: t.music.playNext),
@@ -1076,8 +1074,8 @@ class MediaContextMenuState extends State<MediaContextMenu> {
 
   Future<void> _handleMusicEnqueue(BuildContext context, {required bool playNext}) async {
     final service = context.read<MusicPlaybackService?>();
-    // Menu entries are hidden on the stub; defensive re-check.
-    if (service == null || !service.isAvailable) return;
+    // Menu entries are hidden without a session; defensive re-check.
+    if (service == null) return;
     final queueSessionRevision = service.queueSessionRevision;
     List<MediaItem> tracks;
     try {

lib/widgets/video_controls/sheets/subtitle_search_sheet.dart

@@ -10,7 +10,6 @@ import '../../../focus/input_mode_tracker.dart';
 import '../../../i18n/strings.g.dart';
 import '../../../mixins/controller_disposer_mixin.dart';
 import '../../../models/plex/plex_subtitle_search_result.dart';
-import '../../../services/plex_client.dart';
 import '../../../services/settings_service.dart';
 import '../../../utils/language_codes.dart';
 import '../../../utils/provider_extensions.dart';
@@ -103,8 +102,7 @@ class _SubtitleSearchSheetState extends State<SubtitleSearchSheet> with Controll
     });
 
     try {
-      final neutral = context.tryGetMediaClientForServer(ServerId(widget.serverId));
-      final client = neutral is PlexClient ? neutral : null;
+      final client = context.tryGetPlexClientForServer(ServerId(widget.serverId));
       if (client == null) {
         if (!mounted || generation != _searchGeneration) return;
         setState(() => _isSearching = false);
@@ -185,10 +183,7 @@ class _SubtitleSearchSheetState extends State<SubtitleSearchSheet> with Controll
     setState(() => _downloadingKey = result.key);
 
     try {
-      // Same Plex-only guard as in [_search]. Don't throw if a Jellyfin
-      // server somehow reaches the download path.
-      final neutral = context.tryGetMediaClientForServer(ServerId(widget.serverId));
-      final client = neutral is PlexClient ? neutral : null;
+      final client = context.tryGetPlexClientForServer(ServerId(widget.serverId));
       if (client == null) {
         if (!mounted) return;
         setState(() => _downloadingKey = null);

test/screens/music/album_detail_screen_test.dart

@@ -52,19 +52,6 @@ void main() {
     // Track numbers restart per disc.
     expect(find.text('1'), findsNWidgets(2));
   });
-
-  testWidgets('tapping a track on the stub service shows the not-supported notice', (tester) async {
-    final harness = await _createHarness(_multiDiscTracks());
-
-    await tester.pumpWidget(harness.wrap(const AlbumDetailScreen(album: _album)));
-    await tester.pumpAndSettle();
-
-    await tester.tap(find.text('Track One'));
-    await tester.pump();
-    await tester.pump(const Duration(milliseconds: 300));
-
-    expect(find.text(t.messages.musicNotSupported), findsOneWidget);
-  });
 }
 
 const _album = MediaItem.plex(

test/screens/music/now_playing_screen_test.dart

@@ -54,9 +54,6 @@ class _FakeMusicService extends StubMusicPlaybackService {
     _positionController.add(position);
   }
 
-  @override
-  bool get isAvailable => true;
-
   @override
   MediaItem get currentTrack => track;
 

test/screens/music/queue_sheet_test.dart

@@ -40,9 +40,6 @@ class _FakeQueueService extends StubMusicPlaybackService {
 
   _FakeQueueService(this.tracks);
 
-  @override
-  bool get isAvailable => true;
-
   @override
   MediaItem? get currentTrack => tracks[1];
 

test/services/trackers/future_coalescer_test.dart

@@ -34,4 +34,26 @@ void main() {
     expect(first, 1);
     expect(second, 2);
   });
+
+  test('KeyedFutureCache memoizes successes and evicts failures', () async {
+    final cache = KeyedFutureCache<String, int>();
+    final errors = <Object>[];
+    var calls = 0;
+
+    Future<int> create({required bool fail}) async {
+      calls++;
+      if (fail) throw StateError('boom');
+      return calls;
+    }
+
+    await expectLater(cache.run('a', () => create(fail: true), onError: errors.add), throwsStateError);
+    expect(errors, hasLength(1));
+
+    expect(await cache.run('a', () => create(fail: false)), 2);
+    expect(await cache.run('a', () => create(fail: false)), 2);
+    expect(calls, 2);
+
+    cache.clear();
+    expect(await cache.run('a', () => create(fail: false)), 3);
+  });
 }

test/widgets/media_context_menu_test.dart

@@ -670,9 +670,6 @@ class _RecordingMusicPlaybackService extends StubMusicPlaybackService {
   bool? shuffle;
   int callCount = 0;
 
-  @override
-  bool get isAvailable => true;
-
   @override
   Future<void> playFromList({
     required List<MediaItem> tracks,

test/widgets/music/mini_player_test.dart

@@ -74,9 +74,6 @@ class _FakeMusicService extends StubMusicPlaybackService {
 
   _FakeMusicService({this.track});
 
-  @override
-  bool get isAvailable => true;
-
   @override
   MediaItem? get currentTrack => track;