fix desktop workspace stream fallback

lib/features/desktop/desktop_client.dart

@@ -38,7 +38,6 @@ class DesktopClient {
 
   RTCPeerConnection? _peerConnection;
   RTCDataChannel? _dataChannel;
-  MediaStream? _remoteStream;
 
   final StreamController<MediaStream> _streamController =
       StreamController<MediaStream>.broadcast();
@@ -77,12 +76,14 @@ class DesktopClient {
       _peerConnection = await createPeerConnection(config);
 
       // Listen for remote streams
-      _peerConnection!.onTrack = (event) {
+      _peerConnection!.onTrack = (event) async {
         if (event.track.kind == 'video') {
-          if (event.streams.isNotEmpty) {
-            _remoteStream = event.streams.first;
-            _streamController.add(_remoteStream!);
-          }
+          final remoteStream = await desktopRemoteStreamFromTrack(
+            track: event.track,
+            streams: event.streams,
+          );
+          if (remoteStream == null) return;
+          _streamController.add(remoteStream);
         }
       };
 
@@ -204,7 +205,27 @@ class DesktopClient {
     await _peerConnection?.close();
     _dataChannel = null;
     _peerConnection = null;
-    _remoteStream = null;
     _stateController.add('disconnected');
   }
 }
+
+Future<MediaStream?> desktopRemoteStreamFromTrack({
+  required MediaStreamTrack track,
+  required List<MediaStream> streams,
+  Future<MediaStream> Function(String streamId)? streamFactory,
+}) async {
+  if (track.kind != 'video') {
+    return null;
+  }
+  if (streams.isNotEmpty) {
+    return streams.first;
+  }
+  final factory = streamFactory ?? createLocalMediaStream;
+  final syntheticStream = await factory(
+    'desktop-remote-${track.id}',
+  );
+  // The bridge may deliver a bare video track without an attached stream.
+  // Wrapping it keeps RTCVideoView rendering instead of leaving the panel blank.
+  syntheticStream.addTrack(track);
+  return syntheticStream;
+}

test/features/desktop/desktop_client_test.dart

@@ -3,6 +3,8 @@ import 'package:flutter_webrtc/flutter_webrtc.dart';
 import 'package:xworkmate/features/desktop/desktop_client.dart';
 
 void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
   group('DesktopClient protocol helpers', () {
     test('normalizes WebRTC connection states for view gating', () {
       expect(
@@ -42,5 +44,113 @@ void main() {
       expect(params['width'], 1280);
       expect(params['height'], 720);
     });
+
+    test('creates a synthetic media stream when the bridge omits streams', () async {
+      final track = _FakeMediaStreamTrack(
+        id: 'track-1',
+        kind: 'video',
+      );
+      final createdStreams = <_FakeMediaStream>[];
+
+      final stream = await desktopRemoteStreamFromTrack(
+        track: track,
+        streams: const <MediaStream>[],
+        streamFactory: (streamId) async {
+          final stream = _FakeMediaStream(streamId);
+          createdStreams.add(stream);
+          return stream;
+        },
+      );
+
+      expect(stream, isNotNull);
+      expect(createdStreams, hasLength(1));
+      expect(stream, same(createdStreams.single));
+      expect(createdStreams.single.getVideoTracks(), hasLength(1));
+      expect(createdStreams.single.getVideoTracks().single, same(track));
+    });
+
+    test('prefers the attached remote stream when one is present', () async {
+      final track = _FakeMediaStreamTrack(
+        id: 'track-2',
+        kind: 'video',
+      );
+      final attachedStream = _FakeMediaStream('attached-stream');
+
+      final stream = await desktopRemoteStreamFromTrack(
+        track: track,
+        streams: <MediaStream>[attachedStream],
+        streamFactory: (streamId) async => _FakeMediaStream(streamId),
+      );
+
+      expect(stream, same(attachedStream));
+      expect(stream!.getVideoTracks(), isEmpty);
+    });
   });
 }
+
+class _FakeMediaStreamTrack extends MediaStreamTrack {
+  _FakeMediaStreamTrack({required this.id, required this.kind});
+
+  @override
+  final String id;
+
+  @override
+  final String kind;
+
+  @override
+  String? get label => 'fake';
+
+  @override
+  bool get enabled => true;
+
+  @override
+  set enabled(bool b) {}
+
+  @override
+  bool? get muted => false;
+
+  @override
+  Future<void> stop() async {}
+
+  @override
+  Future<void> dispose() async {}
+}
+
+class _FakeMediaStream extends MediaStream {
+  _FakeMediaStream(String id) : super(id, 'test-owner');
+
+  final List<MediaStreamTrack> _tracks = <MediaStreamTrack>[];
+
+  @override
+  bool? get active => _tracks.isNotEmpty;
+
+  @override
+  Future<void> getMediaTracks() async {}
+
+  @override
+  Future<void> addTrack(MediaStreamTrack track, {bool addToNative = true}) async {
+    _tracks.add(track);
+  }
+
+  @override
+  Future<void> removeTrack(
+    MediaStreamTrack track, {
+    bool removeFromNative = true,
+  }) async {
+    _tracks.remove(track);
+  }
+
+  @override
+  List<MediaStreamTrack> getTracks() => List<MediaStreamTrack>.unmodifiable(_tracks);
+
+  @override
+  List<MediaStreamTrack> getAudioTracks() =>
+      _tracks.where((track) => track.kind == 'audio').toList(growable: false);
+
+  @override
+  List<MediaStreamTrack> getVideoTracks() =>
+      _tracks.where((track) => track.kind == 'video').toList(growable: false);
+
+  @override
+  Future<MediaStream> clone() async => _FakeMediaStream('${id}_clone');
+}