fix: `isRemoteControlEnabled` sync #236

konsalex · 2026-01-25T21:14:43Z

AI generated with fixes from me 👇

Summary

Fixes issue #233 (isRemoteControlEnabled is not correct with new participants).

This PR ensures that late-joining participants receive the correct remote-control state from the sharer, rather than incorrectly assuming remote control is enabled.

Two-pronged fix:

Core (Rust): The sharer now tracks remote-control state internally and rebroadcasts it when new participants join, ensuring late joiners receive the current state immediately

Client (TypeScript): Default isRemoteControlEnabled is true across all join flows. Ideally it would be false, but it creates a small "glitch" with a label of having remote control disabled in the session which I didn't like.

Changes

Core (room_service.rs)

Added is_sharer flag to track if this instance is the screen-sharing authority
Added remote_control_enabled state to track current remote-control setting
On PublishTrack (share start): mark as sharer and publish initial remote-control state
On RoomEvent::ParticipantConnected: if sharer, rebroadcast current state to ensure late joiner sync
On PublishControllerCursorEnabled: update internal state for future rebroadcasts
On share stop: reset sharer flag and remote-control state

Concerns

Currently we have this code which resides inside SharingScreen.tsx, which I think has a probability of missing/dropping a message from sharer, if it will get created a bit slower.

  useDataChannel("remote_control_enabled", (msg) => {
    const decoder = new TextDecoder();
    const payload: TPRemoteControlEnabled = JSON.parse(decoder.decode(msg.payload));
    if (payload.payload.enabled == false) {
      updateCallTokens({
        isRemoteControlEnabled: false,
      });
.....

This part, as it updates the call state, it should live inside the main app's window, so we avoid any race conditions.

Summary by CodeRabbit

Bug Fixes
- Ensures late joiners receive the correct remote-control setting when joining an active screen-share session.
- Prevents redundant state updates to avoid unnecessary UI churn.
New Features
- Remote control now defaults to enabled for sessions.
- Adds clear toasts notifying participants when the sharer enables or disables remote control.

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coderabbitai · 2026-01-25T21:15:04Z

📝 Walkthrough

Walkthrough

Adds a mutex-protected remote_control_enabled: bool to RoomServiceInner (initialized true), updates it on PublishTrack and PublishControllerCursorEnabled, passes the inner Arc into the room event handler, and rebroadcasts the current remote control state to late joiners on ParticipantConnected.

Changes

Cohort / File(s)	Summary
Room service: remote control state `core/src/room_service.rs`	Introduce `remote_control_enabled: Mutex<bool>` in `RoomServiceInner` (init true). Update state on `PublishTrack` and `PublishControllerCursorEnabled`. Pass `inner` into room event task and rebroadcast `RemoteControlEnabled` to late joiners on `ParticipantConnected`.
Frontend: remote control UI updates `tauri/src/components/SharingScreen/SharingScreen.tsx`	Handle remote-control data-channel payloads by early-returning if value unchanged; update `isRemoteControlEnabled` on both enable/disable cases and show corresponding toasts. Minor import formatting changes.

Sequence Diagram

sequenceDiagram
    participant RS as RoomService
    participant RH as RoomEventHandler
    participant P as Participant (late-joiner)

    Note over RS: PublishTrack / PublishControllerCursorEnabled updates rc state
    RS->>RS: Set remote_control_enabled (Mutex)
    RS->>RH: (events stream) room events task has access to inner

    P->>RH: ParticipantConnected
    activate RH
    RH->>RS: Read remote_control_enabled (lock)
    RS-->>RH: remote_control_enabled value
    RH->>P: Publish RemoteControlEnabled event
    deactivate RH

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 I nudged a bool with careful paws,

I locked and set it without a cause,
When late ones hop in, they hear the tale,
Remote control: enabled or frail.
A tiny hop of shared control — applause! 🎉

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: `isRemoteControlEnabled` sync' directly refers to the main objective of the pull request, which is to fix the synchronization of the isRemoteControlEnabled state for late-joining participants.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch fix-isRemoteControlEnabled-

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iparaskev · 2026-01-31T13:36:48Z

I was cleaning up this and while testing it hit a limitation of this approach. There is a race on processing the event in the controller. I had disabled remote control but when the controller joined the room no toaster or indication was shown. Reloading made the icon on the top right to appear. Maybe we should store this in the livekit room metadata instead?

coderabbitai

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

tauri/src/components/SharingScreen/SharingScreen.tsx (1)
130-156: ⚠️ Potential issue | 🟡 Minor

Guard reads stale closure state and can skip legitimate transitions.

If two messages arrive before a re-render completes, the second state transition may be dropped. The callback closes over the render-time isRemoteControlEnabled value. When updateCallTokens triggers a store update, there's a window where rapid follow-up messages still use the old captured value in the guard check.

Compare against a ref that tracks the latest value instead:
🔧 Suggested fix using a ref for the latest value
   const { updateCallTokens, callTokens } = useStore();
   const isRemoteControlEnabled = callTokens?.isRemoteControlEnabled ?? false;
+  const isRemoteControlEnabledRef = useRef(isRemoteControlEnabled);
+  useEffect(() => {
+    isRemoteControlEnabledRef.current = isRemoteControlEnabled;
+  }, [isRemoteControlEnabled]);

   useDataChannel("remote_control_enabled", (msg) => {
     const decoder = new TextDecoder();
     const payload: TPRemoteControlEnabled = JSON.parse(decoder.decode(msg.payload));
     const newValue = payload.payload.enabled;

     // Skip if value matches current state
-    if (newValue === isRemoteControlEnabled) {
+    if (newValue === isRemoteControlEnabledRef.current) {
       return;
     }

konsalex · 2026-02-01T13:15:09Z

TODO: Refactor this to use Livekit's Room metadata. Check if metadata are persistent or not (case for our Rooms implementation because ID is the same)

konsalex added 2 commits January 25, 2026 22:00

fix: sync state for remote control

d02308f

chore: default to true

3493c5e

konsalex requested a review from iparaskev as a code owner January 25, 2026 21:14

fix: remove slop

a779121

fix: don't spam with updates when the state doesn't change

3d4ed8c

coderabbitai bot reviewed Jan 31, 2026

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fix: `isRemoteControlEnabled` sync #236

fix: `isRemoteControlEnabled` sync #236

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