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', (