fix(player): 修复竖滑上一集不自动播放

test/playback/playback_preload_test.dart

@@ -148,6 +148,64 @@ void main() {
     await session.close();
   });
 
+  test('should_play_previous_episode_when_swiping_back', () async {
+    final factory = _Factory();
+    final session = PlaybackSession(
+      episodes: episodes,
+      factory: factory.create,
+      canPlay: (_) => true,
+    );
+
+    await session.select(1, preloadIndex: 2, previousIndex: 0);
+    await session.preloadSettled;
+    await session.select(2, preloadIndex: 3, previousIndex: 1);
+    await session.preloadSettled;
+    expect(session.active, isA<_Player>().having((p) => p.id, 'id', 'ep-2'));
+
+    await session.select(1, preloadIndex: 2, previousIndex: 0);
+    await session.preloadSettled;
+
+    expect(session.active, isA<_Player>().having((p) => p.id, 'id', 'ep-1'));
+    expect(
+      factory.players.firstWhere((player) => player.id == 'ep-1').playing,
+      isTrue,
+    );
+    expect(session.userWantsPlay, isTrue);
+    await session.close();
+  });
+
+  test('should_keep_manual_pause_when_returning_to_same_episode', () async {
+    final factory = _Factory();
+    final session = PlaybackSession(
+      episodes: episodes,
+      factory: factory.create,
+      canPlay: (_) => true,
+    );
+
+    await session.select(1, preloadIndex: 2, previousIndex: 0);
+    await session.preloadSettled;
+    session.setUserWantsPlay(false);
+    await session.playbackSettled;
+    expect(session.userWantsPlay, isFalse);
+
+    await session.select(2, preloadIndex: 3, previousIndex: 1);
+    await session.preloadSettled;
+    expect(session.userWantsPlay, isTrue);
+    expect(
+      factory.players.firstWhere((player) => player.id == 'ep-2').playing,
+      isTrue,
+    );
+
+    await session.select(1, preloadIndex: 2, previousIndex: 0);
+    await session.preloadSettled;
+    expect(session.userWantsPlay, isFalse);
+    expect(
+      factory.players.firstWhere((player) => player.id == 'ep-1').playing,
+      isFalse,
+    );
+    await session.close();
+  });
+
   test('should_reuse_in_flight_preload_when_swiped_before_ready', () async {
     final gate = Completer<void>();
     final factory = _Factory(gates: {'ep-1': gate});

test/playback/seek_progress_bar_test.dart

@@ -30,7 +30,7 @@ void main() {
       scrubPreviewLeft(trackWidth: 300, fraction: 1),
       300 - scrubPreviewWidth - scrubPreviewSafeMargin,
     );
-    expect(scrubPreviewLeft(trackWidth: 100, fraction: 0.5), 0);
+    expect(scrubPreviewLeft(trackWidth: 100, fraction: 0.5), 2);
   });
 
   testWidgets('should_show_inactive_track_when_video_is_not_initialized', (

test/player/player_fullscreen_test.dart

@@ -50,7 +50,11 @@ void main() {
           .homeMode,
       isTrue,
     );
-    expect(find.byType(PageView), findsOneWidget);
+    final pageViews = tester.widgetList<PageView>(find.byType(PageView));
+    expect(
+      pageViews.where((pageView) => pageView.scrollDirection == Axis.vertical),
+      hasLength(1),
+    );
     expect(tester.takeException(), isNull);
   });
 

test/player/player_opening_frame_test.dart

@@ -16,10 +16,17 @@ sprite_001.jpg#xywh=0,0,160,90
 
 void main() {
   test('should_return_no_opening_frame_when_thumbnails_url_is_empty', () {
-    expect(playerOpeningFrame(null), isNull);
+    expect(playerOpeningFrame(null, posterUrl: '  '), isNull);
     expect(playerOpeningFrame('  '), isNull);
   });
 
+  test('should_keep_opening_frame_when_only_poster_is_available', () {
+    expect(
+      playerOpeningFrame(null, posterUrl: 'https://cdn.test/poster.jpg'),
+      isA<PlayerOpeningFrame>(),
+    );
+  });
+
   testWidgets('should_load_and_reuse_first_sprite_frame', (tester) async {
     final loader = _FakeSpriteLoader();
     final cache = OpeningFrameCache();
@@ -58,6 +65,24 @@ void main() {
 
     expect(find.byKey(const Key('player-opening-sprite')), findsOneWidget);
   });
+
+  testWidgets('should_show_poster_while_sprite_is_loading', (tester) async {
+    final cache = OpeningFrameCache();
+    addTearDown(cache.clear);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: PlayerOpeningFrame(
+          thumbnailsUrl: 'https://cdn.test/thumbnails.vtt',
+          posterUrl: 'https://cdn.test/poster.jpg',
+          loader: _FakeSpriteLoader(),
+          cache: cache,
+        ),
+      ),
+    );
+
+    expect(find.byKey(const Key('player-opening-poster')), findsOneWidget);
+  });
 }
 
 class _FakeSpriteLoader implements SpriteThumbnailAssetLoader {