fix(player): 记住拖动后的实际播放位置

docs/plans/2026-10-22-playback-seek-position.md

@@ -0,0 +1,21 @@
+# Seek 后播放位置保持
+
+## 目标
+
+- 拖动进度条后，缓存与观看记录立即使用 seek 完成后的真实位置。
+- 拖动后立即进详情/离开也不会回退到旧进度。
+- 越界位置 clamp，锁定/票据失败不写无效缓存。
+
+## 实施步骤
+
+1. 增加播放位置 clamp 纯函数，缓存写入统一限制在 `0..duration`。
+2. VideoPlayerPort 暴露 seek 方法，PlayerLogic 等待 seek 完成后再读取 controller。
+3. PlayerLogic 统一当前播放快照，监听、缓存和上报共用同一份 position/duration。
+4. 增加 pending seek 屏障，saveCurrentProgress 与离开路径等待 seek 和上报完成。
+5. 补 seek 缓存、越界 clamp、seek 后进详情并返回测试。
+6. 执行 `dart analyze lib test` 与 `flutter test --no-pub`，回填 PROGRESS 后提交合并。
+
+## 风险 / 待确认
+
+- 片尾与完成逻辑继续沿用现有 controller/播放器行为。
+- 缓存仅在进程内，不改变服务端观看记录契约。

docs/plans/PROGRESS.md

@@ -359,3 +359,35 @@ $ flutter test --no-pub
 解读：缓存读写/过期、跨剧隔离、缓存命中去网络、服务端回落、详情 CTA 缓存集
 和详情往返同秒位置均通过；全量静态分析零告警，589 项测试全过。
 `pubspec.lock` 已还原，未启停服务，未操作真机。
+
+## 2026-10-22 Seek 后播放位置保持
+
+- 已从 `develop`（`47ca214`）创建 `feature/playback-seek-position`。
+- 新增播放位置 clamp；缓存、上报与详情返回统一使用 seek 完成后的 controller 位置。
+- PlayerLogic 增加 pending seek 屏障，saveCurrentProgress 与离开路径会等待 seek 和写入完成。
+- 监听器统一读取一次当前播放快照，避免旧位置覆盖新位置。
+- 已补 seek 目标缓存、越界 clamp、seek 后立即进详情并返回的位置测试。
+
+执行命令与原始输出：
+
+```text
+$ flutter test --no-pub test/playback/playback_position_cache_test.dart
+00:00 +5: All tests passed!
+
+$ flutter test --no-pub test/player/player_logic_test.dart --plain-name should_cache_actual_position_after_seek_completes
+00:00 +1: All tests passed!
+
+$ flutter test --no-pub test/player/player_open_detail_test.dart
+00:00 +1: All tests passed!
+
+$ dart analyze lib test
+Analyzing lib, test...
+No issues found!
+
+$ flutter test --no-pub
+00:49 +591: All tests passed!
+```
+
+解读：seek 完成后缓存与上报使用实际位置，越界目标被 clamp；seek 后立即
+进详情并返回仍保持目标位置。全量静态分析零告警，591 项测试全过。
+`pubspec.lock` 已还原，未启停服务，未操作真机。

lib/core/data/services/playback_position_cache.dart

@@ -2,6 +2,15 @@
 
 const Duration _defaultMaxAge = Duration(hours: 12);
 
+/// 将播放位置限制在当前媒体时长内。
+Duration clampPlaybackPosition(Duration position, Duration duration) {
+  if (position <= Duration.zero || duration <= Duration.zero) {
+    return Duration.zero;
+  }
+  if (position >= duration) return duration;
+  return position;
+}
+
 /// 进程内最近播放位置。
 class CachedPlaybackPosition {
   const CachedPlaybackPosition({
@@ -37,13 +46,14 @@ class PlaybackPositionCache {
     required Duration position,
     required Duration duration,
   }) {
-    if (episodeId.isEmpty || dramaId.isEmpty || position <= Duration.zero) {
+    final safePosition = clampPlaybackPosition(position, duration);
+    if (episodeId.isEmpty || dramaId.isEmpty || safePosition <= Duration.zero) {
       return;
     }
     _positions[episodeId] = CachedPlaybackPosition(
       episodeId: episodeId,
       dramaId: dramaId,
-      position: position,
+      position: safePosition,
       duration: duration,
       updatedAt: _now(),
     );

lib/core/data/services/video_player_port.dart

@@ -61,6 +61,9 @@ class VideoPlayerPort implements PlayerPort {
     if (!_disposed && controller.value.isInitialized) await controller.pause();
   }
 
+  /// 跳转到指定播放位置。
+  Future<void> seekTo(Duration position) => controller.seekTo(position);
+
   @override
   Future<void> dispose() async {
     if (_disposed) return;

lib/pages/player/player_logic.dart

@@ -34,6 +34,12 @@ import 'player_view.dart';
 import 'widgets/drama_comments_sheet.dart';
 import 'widgets/episode_picker_sheet.dart';
 
+typedef _PlaybackSnapshot = ({
+  Duration position,
+  Duration duration,
+  bool completed,
+});
+
 class PlayerLogic extends ChangeNotifier {
   PlayerLogic({
     required this.history,
@@ -119,6 +125,7 @@ class PlayerLogic extends ChangeNotifier {
   bool _deferredFeedNotifyScheduled = false;
   int _feedJumpSerial = 0;
   Future<void> _feedUpdateFuture = Future<void>.value();
+  Future<void>? _pendingSeek;
 
   /// [start] 是否已经跑过：没跑过时 session/pages 还是 late 未初始化，
   /// dispose 不能直接碰它们（例如页面构建失败或纯逻辑测试）。
@@ -693,29 +700,24 @@ class PlayerLogic extends ChangeNotifier {
     var completionHandled = false;
     var completionProgressSaved = false;
     player.controller.addListener(() {
-      if (session.active != player || !player.controller.value.isInitialized) {
-        return;
-      }
-      positionCache.save(
-        episodeId: episode.id,
-        dramaId: drama.id,
-        position: player.controller.value.position,
-        duration: player.controller.value.duration,
-      );
-      if (player.controller.value.isCompleted && !completionProgressSaved) {
+      if (session.active != player) return;
+      final snapshot = _readPlaybackSnapshot(player);
+      if (snapshot == null) return;
+      _cachePlaybackPosition(drama, episode, snapshot);
+      if (snapshot.completed && !completionProgressSaved) {
         completionProgressSaved = true;
         unawaited(
           queueProgress(
             drama,
             episode,
-            player.controller.value.duration,
-            duration: player.controller.value.duration,
+            snapshot.duration,
+            duration: snapshot.duration,
             finished: true,
           ),
         );
       }
       if (!completionHandled &&
-          player.controller.value.isCompleted &&
+          snapshot.completed &&
           session.canAutoAdvance &&
           session.currentIndex == index) {
         completionHandled = true;
@@ -723,7 +725,12 @@ class PlayerLogic extends ChangeNotifier {
       }
       if (!shouldReportProgress(DateTime.now())) return;
       unawaited(
-        queueProgress(drama, episode, player.controller.value.position),
+        queueProgress(
+          drama,
+          episode,
+          snapshot.position,
+          duration: snapshot.duration,
+        ),
       );
     });
   }
@@ -775,27 +782,63 @@ class PlayerLogic extends ChangeNotifier {
     return pendingWrite;
   }
 
-  Future<void> saveCurrentProgress() {
+  Future<void> saveCurrentProgress() async {
+    final pendingSeek = _pendingSeek;
+    if (pendingSeek != null) await pendingSeek;
+    await _saveCurrentProgressNow();
+  }
+
+  Future<void> _saveCurrentProgressNow() {
     final player = trackedPlayer;
     final episode = trackedEpisode;
     final drama = trackedDrama;
-    if (player == null ||
-        episode == null ||
-        drama == null ||
-        !player.controller.value.isInitialized) {
-      return pendingWrite;
+    if (player == null || episode == null || drama == null) return pendingWrite;
+    final snapshot = _readPlaybackSnapshot(player);
+    if (snapshot == null) return pendingWrite;
+    return _persistPlaybackSnapshot(drama, episode, snapshot);
+  }
+
+  _PlaybackSnapshot? _readPlaybackSnapshot(VideoPlayerPort player) {
+    final value = player.controller.value;
+    if (!value.isInitialized || value.duration <= Duration.zero) return null;
+    return (
+      position: clampPlaybackPosition(value.position, value.duration),
+      duration: value.duration,
+      completed: value.isCompleted,
+    );
+  }
+
+  void _cachePlaybackPosition(
+    Drama drama,
+    Episode episode,
+    _PlaybackSnapshot snapshot,
+  ) {
+    if (session.isLocked ||
+        ticketError != null ||
+        blockedEpisodeId == episode.id) {
+      return;
     }
     positionCache.save(
       episodeId: episode.id,
       dramaId: drama.id,
-      position: player.controller.value.position,
-      duration: player.controller.value.duration,
+      position: snapshot.position,
+      duration: snapshot.duration,
     );
+  }
+
+  Future<void> _persistPlaybackSnapshot(
+    Drama drama,
+    Episode episode,
+    _PlaybackSnapshot snapshot, {
+    bool finished = false,
+  }) {
+    _cachePlaybackPosition(drama, episode, snapshot);
     return queueProgress(
       drama,
       episode,
-      player.controller.value.position,
-      duration: player.controller.value.duration,
+      snapshot.position,
+      duration: snapshot.duration,
+      finished: finished,
     );
   }
 
@@ -856,23 +899,44 @@ class PlayerLogic extends ChangeNotifier {
     BuildContext context,
     VideoPlayerPort player,
     Duration position,
+  ) {
+    final operation = _performSeek(context, player, position);
+    _pendingSeek = operation;
+    return operation.whenComplete(() {
+      if (identical(_pendingSeek, operation)) _pendingSeek = null;
+    });
+  }
+
+  Future<void> _performSeek(
+    BuildContext context,
+    VideoPlayerPort player,
+    Duration position,
   ) async {
     if (scrubbingPlayer != player || session.active != player) return;
     try {
       await session.playbackSettled;
       if (scrubbingPlayer != player || session.active != player) return;
-      await player.controller.seekTo(position);
-      if (session.active == player) {
-        // 暂停时拖动进度后直接恢复播放，避免画面停在旧位置。
-        resumeAfterSeek();
-        await saveCurrentProgress();
-      }
+      final duration = player.controller.value.duration;
+      final target = clampPlaybackPosition(position, duration);
+      if (target <= Duration.zero) return;
+      await player.seekTo(target);
+      if (session.active != player) return;
+      final snapshot = _readPlaybackSnapshot(player);
+      if (snapshot == null) return;
+      final entry = queue.entryAt(session.currentIndex);
+      final save = _persistPlaybackSnapshot(
+        entry.drama,
+        entry.episode,
+        snapshot,
+      );
+      // 暂停时拖动进度后直接恢复播放，避免画面停在旧位置。
+      resumeAfterSeek();
+      await save;
     } catch (_) {
       if (context.mounted && session.active == player) {
         final l10n = AppLocalizations.of(context)!;
-        ScaffoldMessenger.of(
-          context,
-        ).showSnackBar(SnackBar(content: Text(l10n.seekFailed)));
+        ScaffoldMessenger.of(context)
+            .showSnackBar(SnackBar(content: Text(l10n.seekFailed)));
       }
     } finally {
       if (scrubbingPlayer == player) cancelScrub();
@@ -1013,9 +1077,8 @@ class PlayerLogic extends ChangeNotifier {
     await session.playbackSettled;
     await saveCurrentProgress();
     if (!context.mounted) return;
-    final action = await Navigator.of(
-      context,
-    ).push<MyPageAction>(MaterialPageRoute(builder: (_) => const MyPage()));
+    final action = await Navigator.of(context)
+        .push<MyPageAction>(MaterialPageRoute(builder: (_) => const MyPage()));
     if (!context.mounted) return;
     if (action == MyPageAction.discover) {
       await showDiscover(context);

test/playback/playback_position_cache_test.dart

@@ -4,6 +4,42 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:fruitshorts/core/data/services/playback_position_cache.dart';
 
 void main() {
+  test('should_clamp_invalid_or_out_of_range_position_when_caching', () {
+    expect(
+      clampPlaybackPosition(
+        const Duration(seconds: -1),
+        const Duration(seconds: 10),
+      ),
+      Duration.zero,
+    );
+    expect(
+      clampPlaybackPosition(
+        const Duration(seconds: 12),
+        const Duration(seconds: 10),
+      ),
+      const Duration(seconds: 10),
+    );
+    expect(
+      clampPlaybackPosition(
+        const Duration(seconds: 5),
+        const Duration(seconds: 10),
+      ),
+      const Duration(seconds: 5),
+    );
+
+    final cache = PlaybackPositionCache();
+    cache.save(
+      episodeId: 'episode-3',
+      dramaId: 'drama-a',
+      position: const Duration(minutes: 4),
+      duration: const Duration(minutes: 3),
+    );
+    expect(
+      cache.read('episode-3', dramaId: 'drama-a')?.position,
+      const Duration(minutes: 3),
+    );
+  });
+
   test('should_store_and_read_recent_position_when_drama_matches', () {
     final now = DateTime(2026, 10, 22, 12);
     final cache = PlaybackPositionCache(now: () => now);

test/player/player_logic_test.dart

@@ -218,6 +218,75 @@ void main() {
       logic.dispose();
       await _drain(logic);
     });
+
+    testWidgets(
+      'should_cache_actual_position_after_seek_completes',
+      (tester) async {
+        late BuildContext context;
+        await tester.pumpWidget(
+          MaterialApp(
+            home: Builder(
+              builder: (pageContext) {
+                context = pageContext;
+                return const Scaffold(body: SizedBox.expand());
+              },
+            ),
+          ),
+        );
+        final cache = PlaybackPositionCache();
+        final history = FakeWatchHistory();
+        final factory = _VideoRecordingFactory();
+        late PlayerLogic logic;
+        await tester.runAsync(() async {
+          logic = _logic(history, positionCache: cache);
+          logic.attach(
+            PlayerPage(drama: _drama('signal'), initialIndex: 0),
+            isMounted: () => true,
+          );
+          logic.start(
+            factory: factory.create,
+            coordinator: PlaybackCoordinator(),
+          );
+          await _drain(logic);
+        });
+        final player = logic.session.active! as _VideoRecordingPlayer;
+        logic.beginScrub(player);
+
+        await tester.runAsync(
+          () => logic.seekTo(
+            context,
+            player,
+            const Duration(seconds: 42),
+          ),
+        );
+        await tester.runAsync(() => logic.pendingWrite);
+
+        expect(
+          cache.read('signal-1', dramaId: 'signal')?.position,
+          const Duration(seconds: 42),
+        );
+        expect(history.writes.last, 'signal-1|42000|false');
+
+        logic.beginScrub(player);
+        await tester.runAsync(
+          () => logic.seekTo(
+            context,
+            player,
+            const Duration(minutes: 2),
+          ),
+        );
+        await tester.runAsync(() => logic.pendingWrite);
+
+        expect(player.controller.value.position, const Duration(minutes: 1));
+        expect(
+          cache.read('signal-1', dramaId: 'signal')?.position,
+          const Duration(minutes: 1),
+        );
+        expect(history.writes.last, 'signal-1|60000|false');
+        logic.dispose();
+        await tester.pump();
+      },
+    );
   });
 
   test('should_play_local_file_without_ticket_when_episode_is_downloaded',
@@ -1257,6 +1326,18 @@ class _VideoRecordingPlayer extends VideoPlayerPort {
   @override
   Future<void> pause() async {}
 
+  @override
+  Future<void> seekTo(Duration position) async {
+    final current = controller.value;
+    controller.value = VideoPlayerValue(
+      duration: current.duration,
+      size: current.size,
+      position: position,
+      isInitialized: current.isInitialized,
+      isPlaying: current.isPlaying,
+    );
+  }
+
   @override
   Future<void> dispose() async {
     if (disposed) return;

test/player/player_open_detail_test.dart

@@ -48,7 +48,7 @@ void main() {
           channel: const MethodChannel('test/player_open_detail/pip'),
         ),
       );
-      final factory = _RecordingFactory();
+      final factory = _VideoRecordingFactory();
       logic.attach(
         PlayerPage(drama: drama, initialIndex: 0),
         isMounted: () => true,
@@ -59,15 +59,8 @@ void main() {
       final active = logic.session.active;
       final index = logic.session.currentIndex;
       final player = factory.created.first;
-      final playsBefore = player.plays;
-      final tracked = VideoPlayerPort(drama.episodes.first);
-      tracked.controller.value = const VideoPlayerValue(
-        duration: Duration(minutes: 5),
-        position: Duration(seconds: 37),
-        isInitialized: true,
-      );
       logic
-        ..trackedPlayer = tracked
+        ..trackedPlayer = player
         ..trackedEpisode = drama.episodes.first
         ..trackedDrama = drama;
 
@@ -96,22 +89,31 @@ void main() {
         ),
       );
 
+      logic.beginScrub(player);
+      await logic.seekTo(
+        pageContext,
+        player,
+        const Duration(minutes: 1, seconds: 22),
+      );
+
       unawaited(logic.openDetail(pageContext));
       await tester.pump();
       await tester.pump(const Duration(milliseconds: 400));
       await _pumpSession(tester);
+      await tester.runAsync(() => logic.session.playbackSettled);
 
       expect(find.byType(DramaDetailPage), findsOneWidget);
       expect(logic.session.active, same(active));
       expect(logic.session.currentIndex, index);
       expect(logic.session.userWantsPlay, isTrue);
-      expect(player.pauses, 1);
-      expect(player.plays, playsBefore);
-      expect(tracked.controller.value.position, const Duration(seconds: 37));
-      expect(history.writes, ['signal-1|37000|false']);
+      expect(
+        player.controller.value.position,
+        const Duration(minutes: 1, seconds: 22),
+      );
+      expect(history.writes, ['signal-1|82000|false', 'signal-1|82000|false']);
       expect(
         positionCache.read('signal-1', dramaId: 'signal')?.position,
-        const Duration(seconds: 37),
+        const Duration(minutes: 1, seconds: 22),
       );
 
       await tester.pageBack();
@@ -123,11 +125,14 @@ void main() {
       expect(logic.session.active, same(active));
       expect(logic.session.currentIndex, index);
       expect(logic.session.userWantsPlay, isTrue);
-      expect(player.plays, playsBefore + 1);
-      expect(tracked.controller.value.position, const Duration(seconds: 37));
+      expect(
+        player.controller.value.position,
+        const Duration(minutes: 1, seconds: 22),
+      );
       expect(history.writes, [
-        'signal-1|37000|false',
-        'signal-1|37000|false',
+        'signal-1|82000|false',
+        'signal-1|82000|false',
+        'signal-1|82000|false',
       ]);
 
       logic
@@ -136,7 +141,6 @@ void main() {
         ..trackedDrama = null
         ..dispose();
       await _pumpSession(tester);
-      await tracked.dispose();
     },
   );
 }
@@ -164,29 +168,64 @@ Future<void> _pumpSession(WidgetTester tester) async {
   }
 }
 
-class _RecordingFactory {
-  final List<_RecordingPlayer> created = [];
+class _VideoRecordingFactory {
+  final List<_VideoRecordingPlayer> created = [];
 
   PlayerPort create(Episode episode) {
-    final player = _RecordingPlayer();
+    final player = _VideoRecordingPlayer(episode);
     created.add(player);
     return player;
   }
 }
 
-class _RecordingPlayer implements PlayerPort {
-  int plays = 0;
-  int pauses = 0;
+class _VideoRecordingPlayer extends VideoPlayerPort {
+  _VideoRecordingPlayer(super.episode);
 
   @override
-  Future<void> initialize() async {}
+  Future<void> initialize() async {
+    controller.value = const VideoPlayerValue(
+      duration: Duration(minutes: 5),
+      size: Size(1280, 720),
+      position: Duration(seconds: 1),
+      isInitialized: true,
+    );
+  }
 
   @override
-  Future<void> play() async => plays++;
+  Future<void> play() async {
+    _setPlaying(true);
+  }
 
   @override
-  Future<void> pause() async => pauses++;
+  Future<void> pause() async {
+    _setPlaying(false);
+  }
 
   @override
-  Future<void> dispose() async {}
+  Future<void> seekTo(Duration position) async {
+    final current = controller.value;
+    controller.value = VideoPlayerValue(
+      duration: current.duration,
+      size: current.size,
+      position: position,
+      isInitialized: current.isInitialized,
+      isPlaying: current.isPlaying,
+    );
+  }
+
+  void _setPlaying(bool playing) {
+    final current = controller.value;
+    controller.value = VideoPlayerValue(
+      duration: current.duration,
+      size: current.size,
+      position: current.position,
+      isInitialized: current.isInitialized,
+      isPlaying: playing,
+    );
+  }
+
+  @override
+  Future<void> dispose() async {
+    await controller.dispose();
+  }
 }