fix: unblock watch together resume

close #961

lib/watch_together/providers/watch_together_provider.dart

@@ -432,6 +432,7 @@ class WatchTogetherProvider with ChangeNotifier {
       final disconnectedName = _participants.where((p) => p.peerId == peerId).map((p) => p.displayName).firstOrNull;
 
       _participants.removeWhere((p) => p.peerId == peerId);
+      unawaited(_syncManager?.handlePeerDisconnected(peerId));
 
       // If host disconnected unexpectedly, start grace period for reconnection.
       // Skip if the host already sent a deliberate leave message.

lib/watch_together/services/watch_together_sync_manager.dart

@@ -121,6 +121,9 @@ class WatchTogetherSyncManager {
     _player = player;
     _lastKnownPlaying = player.state.playing;
     _lastKnownRate = player.state.rate;
+    if (player.state.playing) {
+      _firstPlayCompleted = true;
+    }
 
     _setupPlayerSubscriptions();
     _setupMessageSubscription();
@@ -174,6 +177,14 @@ class WatchTogetherSyncManager {
     appLogger.d('WatchTogether: Initialized $otherCount existing participants (host=${_session.isHost})');
   }
 
+  /// Remove readiness tracking for a peer that dropped at the relay level.
+  Future<void> handlePeerDisconnected(String peerId) async {
+    if (_peerReady.remove(peerId) != null) {
+      appLogger.d('WatchTogether: Removed disconnected peer readiness: $peerId');
+      await _resumeDeferredPlayIfReady(_playerAttachmentGeneration);
+    }
+  }
+
   /// Detach the player and stop sync
   void detachPlayer() {
     _playerAttachmentGeneration++;
@@ -631,6 +642,7 @@ class WatchTogetherSyncManager {
       case SyncMessageType.leave:
         if (message.peerId != null) {
           _peerReady.remove(message.peerId);
+          await _resumeDeferredPlayIfReady(queuedAttachmentGeneration);
         }
         break;
 
@@ -668,15 +680,7 @@ class WatchTogetherSyncManager {
           _peerReady[message.peerId!] = message.bufferingState ?? false;
           appLogger.d('WatchTogether: Peer ${message.peerId} player ready: ${message.bufferingState}');
 
-          if (_deferredPlay && isAllReady) {
+          await _resumeDeferredPlayIfReady(queuedAttachmentGeneration);
-            _setDeferredPlay(false);
-            _firstPlayCompleted = true;
-            final pos = _deferredPlayPosition;
-            _deferredPlayPosition = null;
-            await _applyRemotePlay(position: pos, expectedAttachmentGeneration: queuedAttachmentGeneration);
-            // Broadcast play to all peers now that everyone is ready
-            _broadcastPlayPause(true);
-          }
         }
         break;
 
@@ -714,12 +718,25 @@ class WatchTogetherSyncManager {
         );
         if (!didPlay) return false;
 
+        _firstPlayCompleted = true;
         _lastKnownPlaying = true;
         return true;
       },
     );
   }
 
+  Future<void> _resumeDeferredPlayIfReady(int expectedAttachmentGeneration) async {
+    if (!_deferredPlay || !isAllReady) return;
+
+    _setDeferredPlay(false);
+    _firstPlayCompleted = true;
+    final pos = _deferredPlayPosition;
+    _deferredPlayPosition = null;
+    await _applyRemotePlay(position: pos, expectedAttachmentGeneration: expectedAttachmentGeneration);
+    // Broadcast play to all peers now that everyone is ready.
+    _broadcastPlayPause(true);
+  }
+
   /// Apply remote pause command
   Future<bool> _applyRemotePause({int? expectedAttachmentGeneration}) async {
     return _runGuardedRemoteAction(

test/watch_together/watch_together_sync_manager_test.dart

@@ -0,0 +1,229 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:plezy/mpv/mpv.dart';
+import 'package:plezy/watch_together/models/sync_message.dart';
+import 'package:plezy/watch_together/models/watch_session.dart';
+import 'package:plezy/watch_together/services/watch_together_peer_service.dart';
+import 'package:plezy/watch_together/services/watch_together_sync_manager.dart';
+
+void main() {
+  group('WatchTogetherSyncManager deferred play', () {
+    test('does not re-enter initial load gate after attaching an already-playing player', () async {
+      final peerService = _FakeWatchTogetherPeerService(peerId: 'host');
+      final player = _FakePlayer(playing: true, position: const Duration(minutes: 3));
+      final manager = _hostManager(peerService);
+      final deferredStates = <bool>[];
+      manager.onDeferredPlayChanged = deferredStates.add;
+
+      manager.initializeParticipants(['host', 'guest']);
+      manager.attachPlayer(player);
+
+      await player.emitPlaying(false);
+      await player.emitPlaying(true);
+
+      expect(deferredStates, isNot(contains(true)));
+      expect(player.state.playing, isTrue);
+
+      manager.dispose();
+      await player.dispose();
+      await peerService.close();
+    });
+
+    test('remote play completion prevents a later local resume from using the initial load gate', () async {
+      final peerService = _FakeWatchTogetherPeerService(peerId: 'guest');
+      final player = _FakePlayer(playing: false, position: const Duration(seconds: 10));
+      final manager = _guestManager(peerService, controlMode: ControlMode.anyone);
+      final deferredStates = <bool>[];
+      manager.onDeferredPlayChanged = deferredStates.add;
+
+      manager.initializeParticipants(['guest', 'host', 'other']);
+      manager.attachPlayer(player);
+
+      peerService.emit(SyncMessage.playerReady(peerId: 'other', ready: false));
+      await _settle();
+
+      peerService.emit(SyncMessage.play(peerId: 'host', position: const Duration(seconds: 20)));
+      await _settle();
+      expect(player.state.playing, isTrue);
+
+      await player.emitPlaying(false);
+      await player.emitPlaying(true);
+
+      expect(deferredStates, isNot(contains(true)));
+      expect(player.state.playing, isTrue);
+
+      manager.dispose();
+      await player.dispose();
+      await peerService.close();
+    });
+
+    test('removing a disconnected not-ready peer resumes deferred play', () async {
+      final peerService = _FakeWatchTogetherPeerService(peerId: 'host');
+      final player = _FakePlayer(playing: false, position: const Duration(minutes: 5));
+      final manager = _hostManager(peerService);
+      final deferredStates = <bool>[];
+      manager.onDeferredPlayChanged = deferredStates.add;
+
+      manager.initializeParticipants(['host', 'guest']);
+      manager.attachPlayer(player);
+
+      await player.emitPlaying(true);
+
+      expect(deferredStates, contains(true));
+      expect(player.state.playing, isFalse);
+
+      await manager.handlePeerDisconnected('guest');
+
+      expect(deferredStates, containsAllInOrder([true, false]));
+      expect(player.state.playing, isTrue);
+      expect(peerService.broadcasts.where((m) => m.type == SyncMessageType.play), isNotEmpty);
+
+      manager.dispose();
+      await player.dispose();
+      await peerService.close();
+    });
+  });
+}
+
+WatchTogetherSyncManager _hostManager(_FakeWatchTogetherPeerService peerService) {
+  return WatchTogetherSyncManager(
+    peerService: peerService,
+    session: const WatchSession(
+      sessionId: 'ROOM1',
+      role: SessionRole.host,
+      controlMode: ControlMode.hostOnly,
+      state: SessionState.connected,
+      hostPeerId: 'host',
+    ),
+    displayName: 'Host',
+  );
+}
+
+WatchTogetherSyncManager _guestManager(_FakeWatchTogetherPeerService peerService, {required ControlMode controlMode}) {
+  return WatchTogetherSyncManager(
+    peerService: peerService,
+    session: WatchSession(
+      sessionId: 'ROOM1',
+      role: SessionRole.guest,
+      controlMode: controlMode,
+      state: SessionState.connected,
+      hostPeerId: 'host',
+    ),
+    displayName: 'Guest',
+  );
+}
+
+Future<void> _settle() async {
+  await Future<void>.delayed(Duration.zero);
+  await Future<void>.delayed(Duration.zero);
+}
+
+class _FakeWatchTogetherPeerService extends WatchTogetherPeerService {
+  _FakeWatchTogetherPeerService({required this.peerId}) : super(customBaseUrl: 'http://localhost');
+
+  final String peerId;
+  final StreamController<SyncMessage> _messages = StreamController<SyncMessage>.broadcast();
+  final List<SyncMessage> broadcasts = [];
+  final Map<String, List<SyncMessage>> sentMessages = {};
+
+  @override
+  String? get myPeerId => peerId;
+
+  @override
+  Stream<SyncMessage> get onMessageReceived => _messages.stream;
+
+  @override
+  void broadcast(SyncMessage message) {
+    broadcasts.add(message);
+  }
+
+  @override
+  void sendTo(String peerId, SyncMessage message) {
+    sentMessages.putIfAbsent(peerId, () => []).add(message);
+  }
+
+  void emit(SyncMessage message) {
+    _messages.add(message);
+  }
+
+  Future<void> close() => _messages.close();
+}
+
+class _FakePlayer implements Player {
+  _FakePlayer({bool playing = false, Duration position = Duration.zero})
+    : _state = PlayerState(playing: playing, buffering: false, position: position);
+
+  PlayerState _state;
+  bool _disposed = false;
+
+  final StreamController<bool> _playingController = StreamController<bool>.broadcast();
+  final StreamController<bool> _bufferingController = StreamController<bool>.broadcast();
+  final StreamController<double> _rateController = StreamController<double>.broadcast();
+
+  @override
+  PlayerState get state => _state;
+
+  @override
+  PlayerStreams get streams => PlayerStreams(
+    playing: _playingController.stream,
+    completed: const Stream<bool>.empty(),
+    buffering: _bufferingController.stream,
+    position: const Stream<Duration>.empty(),
+    duration: const Stream<Duration>.empty(),
+    seekable: const Stream<bool>.empty(),
+    buffer: const Stream<Duration>.empty(),
+    volume: const Stream<double>.empty(),
+    rate: _rateController.stream,
+    tracks: const Stream<Tracks>.empty(),
+    track: const Stream<TrackSelection>.empty(),
+    log: const Stream<PlayerLog>.empty(),
+    error: const Stream<PlayerError>.empty(),
+    audioDevice: const Stream<AudioDevice>.empty(),
+    audioDevices: const Stream<List<AudioDevice>>.empty(),
+    bufferRanges: const Stream<List<BufferRange>>.empty(),
+    playbackRestart: const Stream<void>.empty(),
+    backendSwitched: const Stream<void>.empty(),
+  );
+
+  Future<void> emitPlaying(bool value) async {
+    _state = _state.copyWith(playing: value);
+    _playingController.add(value);
+    await _settle();
+  }
+
+  @override
+  Future<void> play() async {
+    _state = _state.copyWith(playing: true);
+  }
+
+  @override
+  Future<void> pause() async {
+    _state = _state.copyWith(playing: false);
+  }
+
+  @override
+  Future<void> seek(Duration position) async {
+    _state = _state.copyWith(position: position);
+  }
+
+  @override
+  Future<void> setRate(double rate) async {
+    _state = _state.copyWith(rate: rate);
+    _rateController.add(rate);
+  }
+
+  @override
+  bool get disposed => _disposed;
+
+  @override
+  Future<void> dispose() async {
+    _disposed = true;
+    await _playingController.close();
+    await _bufferingController.close();
+    await _rateController.close();
+  }
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}