fix(web): disable adaptiveStream so screen-share video isn't paused

apps/web/src/hooks/useWebRTCSFU.test.ts

@@ -64,8 +64,12 @@ class MockRoom {
 
 let mockRoomInstance: MockRoom;
 
+// Capture the Room constructor options so we can assert adaptiveStream is off.
+const { roomCtorSpy } = vi.hoisted(() => ({ roomCtorSpy: vi.fn() }));
+
 vi.mock('livekit-client', () => ({
-  Room: vi.fn().mockImplementation(() => {
+  Room: vi.fn().mockImplementation((opts: unknown) => {
+    roomCtorSpy(opts);
     mockRoomInstance = new MockRoom();
     return mockRoomInstance;
   }),
@@ -167,4 +171,16 @@ describe('useWebRTCSFU', () => {
     expect(thirdStream?.getAudioTracks()).toHaveLength(0);
     expect(thirdStream?.getVideoTracks()).toHaveLength(1);
   });
+
+  it('creates the room with adaptiveStream disabled so screen-share video is not paused', async () => {
+    await act(async () => {
+      renderHook(() => useWebRTCSFU({ sessionId: 'session-1', participantId: 'viewer-1' }));
+      await Promise.resolve();
+      await Promise.resolve();
+      await Promise.resolve();
+      await Promise.resolve();
+    });
+
+    expect(roomCtorSpy).toHaveBeenCalledWith(expect.objectContaining({ adaptiveStream: false }));
+  });
 });

apps/web/src/hooks/useWebRTCSFU.ts

@@ -357,9 +357,15 @@ export function useWebRTCSFU({
         data: { token: string; url: string; roomName: string };
       };
 
-      // Create and connect room
+      // Create and connect room.
+      // adaptiveStream pauses video tracks that livekit doesn't see attached to
+      // a visible element via track.attach(). We render through a manually built
+      // MediaStream on a <video> srcObject, so livekit never registers the
+      // element and would pause the screen-share video — audio keeps flowing,
+      // video stays black. Disable it: the viewer always shows the one presenter
+      // stream, so there's nothing to adaptively pause.
       const room = new Room({
-        adaptiveStream: true,
+        adaptiveStream: false,
         dynacast: true,
       });