fix(lotus): screenshare-audio mute survives a re-share — mute via the renderer, not setVolume

"Mute Screenshare Audio" (io.lotus.set_deafen screenshareAudioMuted) used
RemoteParticipant.setVolume(0, ScreenShareAudio). EC's own createVolumeControls
writes volume 1 through the same setter the moment a new screenshare media item
resolves, so when the sharer stopped and re-shared (or a late joiner shared)
the audio came back at full volume while the host button still said
"Unmute Screenshare Audio". Reproduced on the local calls stack with two
headless clients: after a re-share the screen_share_audio element read vol=1.

Now the flag is a global behavior (muteScreenshareAudio$) that
LivekitRoomAudioRenderer turns into the `muted` prop of every
Track.Source.ScreenShareAudio element — the exact mechanism deafen already uses
(pub.setEnabled(false): the server stops sending). Verified via the
RemoteTrackPublication behind each <audio>: the re-published track (new sid)
mounts with enabled=false while muted and re-enables on unmute; deafen +
undeafen leaves it muted; teardown resets the flag so the next call starts
clean. Unit tests updated; renderer test asserts only ScreenShareAudio
elements get muted by the new prop.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/lotus/lotusDeafen.ts

@@ -5,19 +5,13 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import {
-  type RemoteParticipant,
-  type Room as LivekitRoom,
-  RoomEvent,
-  Track,
-} from "livekit-client";
 import { logger } from "matrix-js-sdk/lib/logger";
 import { type IWidgetApiRequest } from "matrix-widget-api";
 
-import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
 import { setAudioEnabled$ } from "../controls";
 import { widget } from "../widget";
 import { LotusWidgetActions } from "./lotusActions";
+import { setScreenshareAudioMuted$ } from "./lotusScreenshareAudio";
 
 /**
  * Handle the host's `io.lotus.set_deafen` toWidget action, replacing cinny's
@@ -41,22 +35,23 @@ import { LotusWidgetActions } from "./lotusActions";
  * volume/mute state.
  *
  * `screenshareAudioMuted` is a NARROWER, independent host control (drop shared
- * tab/game audio while still hearing voices). EC has no global per-source mute,
- * so that one still has to go through
- * `RemoteParticipant.setVolume(volume, Track.Source.ScreenShareAudio)` — whose
- * verified signature in livekit-client ^2.18.1 is
- * `setVolume(volume, source?: Track.Source.Microphone | Track.Source.ScreenShareAudio)`.
- * It is re-applied to late joiners via `RoomEvent.ParticipantConnected`, and we
- * only ever restore participants we muted ourselves. Known limitation: EC's own
- * screenshare volume slider writes the same `volumeMap`, so a user who moves
- * that slider while screenshare audio is host-muted wins; the mic path (the
- * actual deafen) is no longer affected by that race at all.
+ * tab/game audio while still hearing voices). It goes through the same
+ * mechanism as deafen — a global behavior (`muteScreenshareAudio$`) that
+ * `LivekitRoomAudioRenderer` turns into the `muted` prop of every
+ * `Track.Source.ScreenShareAudio` element — rather than
+ * `RemoteParticipant.setVolume(0, ScreenShareAudio)`: EC's own
+ * `createVolumeControls` writes volume 1 through that very setter whenever a
+ * new screenshare media item resolves, so a sharer who stopped and re-shared
+ * (or a late joiner's share) came back at full volume while the host's button
+ * still said "Unmute Screenshare Audio".
  *
  * Undeafen restores the user's OWN output-enabled state as it was before the
  * deafen (and never touches the `mute-all-audio` setting), so a user who had
  * already muted all audio themselves stays muted.
  *
- * State is closure-scoped (per invocation, matching the sibling lotus modules).
+ * State is closure-scoped (per invocation, matching the sibling lotus modules);
+ * the screenshare-audio flag additionally lives in `setScreenshareAudioMuted$`
+ * so the renderer can read it, and is reset on teardown.
  * Applying the same state twice is a no-op, so the host's
  * `CallControl.resendForkState()` after a reconnect is safe. The host re-sends
  * the current state on every call join (CallControl.forceState), so a fresh
@@ -64,7 +59,7 @@ import { LotusWidgetActions } from "./lotusActions";
  *
  * No effect unless the host sends the action. Returns a teardown function.
  */
-export function startLotusDeafen(vm: CallViewModel): () => void {
+export function startLotusDeafen(): () => void {
   const w = widget;
   if (!w) return () => undefined;
 
@@ -107,53 +102,6 @@ export function startLotusDeafen(vm: CallViewModel): () => void {
     }
   });
 
-  // Participants whose screenshare audio WE turned down, so undoing the host's
-  // screenshare mute never writes a volume to anyone else.
-  const screenshareMuted = new Set<RemoteParticipant>();
-
-  const applyToParticipant = (p: RemoteParticipant): void => {
-    if (screenshareAudioMuted) {
-      p.setVolume(0, Track.Source.ScreenShareAudio);
-      screenshareMuted.add(p);
-    } else if (screenshareMuted.delete(p)) {
-      p.setVolume(1, Track.Source.ScreenShareAudio);
-    }
-  };
-
-  const applyToRoom = (room: LivekitRoom): void =>
-    room.remoteParticipants.forEach(applyToParticipant);
-
-  // Per-room ParticipantConnected listeners, so LATE JOINERS pick up the
-  // current screenshare-audio mute the moment they connect. Drive off the
-  // local participant's connection(s), not `livekitRoomItems$` — that stream is
-  // empty until a matrix-validated REMOTE member resolves, so listeners would
-  // be attached too late for the first joiner (the sibling lotus modules all
-  // use `allConnections$` for the same reason).
-  const roomListeners = new Map<LivekitRoom, () => void>();
-  let rooms: LivekitRoom[] = [];
-
-  const sub = vm.allConnections$.subscribe((data) => {
-    const next = data.getConnections().map((c) => c.livekitRoom);
-    rooms = next;
-    // Detach listeners for rooms that went away.
-    for (const [room, off] of roomListeners) {
-      if (!next.includes(room)) {
-        off();
-        roomListeners.delete(room);
-      }
-    }
-    // Attach to new rooms + apply the current state to their participants.
-    for (const room of next) {
-      if (!roomListeners.has(room)) {
-        room.on(RoomEvent.ParticipantConnected, applyToParticipant);
-        roomListeners.set(room, () =>
-          room.off(RoomEvent.ParticipantConnected, applyToParticipant),
-        );
-        applyToRoom(room);
-      }
-    }
-  });
-
   const handler = (ev: CustomEvent<IWidgetApiRequest>): void => {
     w.api.transport.reply(ev.detail, {});
     const data = ev.detail.data as
@@ -168,20 +116,18 @@ export function startLotusDeafen(vm: CallViewModel): () => void {
       `[lotus] set_deafen: deafened=${deafened} screenshareAudioMuted=${screenshareAudioMuted}`,
     );
     applyGlobalMute();
-    rooms.forEach(applyToRoom);
+    if (setScreenshareAudioMuted$.value !== screenshareAudioMuted)
+      setScreenshareAudioMuted$.next(screenshareAudioMuted);
   };
 
   w.lazyActions.on(LotusWidgetActions.SetDeafen, handler);
   return () => {
-    sub.unsubscribe();
-    for (const off of roomListeners.values()) off();
-    roomListeners.clear();
     // Leave the user's own output state as they had it before deafen.
     if (deafened) {
       deafened = false;
       applyGlobalMute();
     }
-    screenshareMuted.clear();
+    if (setScreenshareAudioMuted$.value) setScreenshareAudioMuted$.next(false);
     audioSub.unsubscribe();
     w.lazyActions.off(LotusWidgetActions.SetDeafen, handler);
   };