feat(frontend): shared pod-wide test audio

Make the "Test audio" connectivity check pod-wide instead of local to the
publisher. Shared on/off state is derived from the presence of the podman-beat
track across participants (self-syncing on join/leave). Any participant can
stop it: the owner unpublishes directly; non-owners send a new additive
BEAT_STOP data message that the owner honors. Drives the button label, status
line, and status waveform for everyone, and guards against rapid-double-click
double-publish and mid-start unmount leaks.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/test-audio.md

@@ -0,0 +1,64 @@
+# Shared Test Audio — pod-wide connectivity check
+
+> Spec for the `frontend/src/livekit/useBeat.ts` + `PodView.tsx` test-audio
+> behavior and the additive `BEAT_STOP` data message. Satisfies the
+> documentation-first gate for those files.
+
+## Why
+
+The **Test audio** button is PodMan's pre-flight check that the LiveKit audio
+path works for the whole pod — the same path the urgent Gemini-TTS voice
+escalation rides on. Today the beat is published correctly but its on/off state
+is **local to the publisher**: teammates can't see it's playing and can't stop
+it. This makes it a shared, pod-wide toggle so a judge sees the state flip on
+every screen at once.
+
+## Behavior
+
+- Any participant clicks **Test audio** → they publish the `podman-beat` audio
+  track (Web Audio, `lib/beat.ts`). Everyone auto-subscribes and hears it.
+- The shared on/off state is **derived from the track's presence**, not a synced
+  flag — so it self-syncs across joins/leaves and can't drift from reality. The
+  publisher is the **owner**.
+- Anyone can stop it:
+  - Owner clicks **Stop audio** → unpublishes its own track directly.
+  - Non-owner clicks **Stop (`<owner>`'s)** → sends `BEAT_STOP`; the owner
+    unpublishes. (LiveKit forbids unpublishing another participant's track, so a
+    request is the only way.)
+- The Status card shows `publishing` / `<owner> playing` / `ready`, and the
+  waveform animates (`active`) for everyone while the test is live.
+
+## State derivation (source of truth = the track)
+
+`useBeat(room)` returns `{ on, by, mine }`, recomputed from the presence of a
+track named `podman-beat` across `localParticipant` + `remoteParticipants` on
+these events: `LocalTrackPublished/Unpublished`, `TrackPublished/Unpublished`,
+`TrackSubscribed/Unsubscribed`, `ParticipantConnected/Disconnected`. Owner
+disconnect and late-join sync therefore need no extra messaging.
+
+## Contract (additive)
+
+`shared/src/messages.ts` — one new message on the existing `podman.intervention`
+data topic:
+
+    | { type: 'BEAT_STOP' }   // any participant → owner: stop the shared beat
+
+Additive to the `DataMessage` union; existing consumers ignore unknown types.
+**No backend / API change.**
+
+## Known limitation (LiveKit constraint)
+
+A client can only unpublish **its own** tracks, so a non-owner's **Stop** is a
+`BEAT_STOP` _request_ the owner must honor. If the owner disconnects **uncleanly**
+(crash / network drop), the SFU keeps the track published until it times the
+participant out — during that window the beat keeps playing and non-owners can't
+stop it. A clean disconnect clears it immediately via `ParticipantDisconnected`.
+Demo mitigation: have the same person who starts the test also stop it.
+
+## Files
+
+- `shared/src/messages.ts` — `BEAT_STOP` message (additive).
+- `frontend/src/livekit/useBeat.ts` — `useBeat(room)` hook.
+- `frontend/src/components/PodView.tsx` — button label, status line, waveform
+  `active` driven by the hook.
+- `frontend/src/lib/beat.ts` — unchanged (existing Web-Audio beat source).

frontend/src/components/PodView.tsx

@@ -22,7 +22,7 @@ import {
 } from 'lucide-react';
 import type { Room, RemoteTrack, RemoteTrackPublication, RemoteParticipant } from 'livekit-client';
 import type { Pod, PodActivityEvent, PodActivityKind, PodActivitySource } from '@podman/shared';
-import { startBeat, type BeatHandle } from '../lib/beat.js';
+import { useBeat } from '../livekit/useBeat.js';
 import { useInterventions, primeSpeech } from '../livekit/useInterventions.js';
 import { usePodActivity } from '../hooks/use-pod-activity.js';
 import LiveWaveform from '@/components/ruixen/live-waveform';
@@ -109,7 +109,6 @@ export function PodView({
 }) {
   const [participants, setParticipants] = useState<PInfo[]>([]);
   const [sharing, setSharing] = useState(false);
-  const [playingBeat, setPlayingBeat] = useState(false);
   const [note, setNote] = useState<string | null>(null);
   const [audioBlocked, setAudioBlocked] = useState(false);
   const [leftStreamOpen, setLeftStreamOpen] = useState(() =>
@@ -119,10 +118,10 @@ export function PodView({
     readStoredBool('podman.teamStreamOpen', true),
   );
   const { active, hermes, voiceCue, actionUrl, respond } = useInterventions(room);
+  const { beat, toggleBeat: runBeat } = useBeat(room);
   const activity = usePodActivity(team.id, me);
 
   const audioRef = useRef<HTMLDivElement>(null);
-  const beatRef = useRef<BeatHandle | null>(null);
   const screenTrackRef = useRef<MediaStreamTrack | null>(null);
   const onLeaveRef = useRef(onLeave);
   onLeaveRef.current = onLeave;
@@ -179,8 +178,6 @@ export function PodView({
 
   useEffect(() => {
     return () => {
-      beatRef.current?.stop();
-      beatRef.current = null;
       screenTrackRef.current?.stop();
       screenTrackRef.current = null;
     };
@@ -194,22 +191,10 @@ export function PodView({
     localStorage.setItem('podman.teamStreamOpen', String(rightStreamOpen));
   }, [rightStreamOpen]);
 
-  async function toggleBeat() {
-    if (!room) return;
+  async function onToggleBeat() {
     setNote(null);
     try {
-      if (playingBeat) {
-        if (beatRef.current) await room.localParticipant.unpublishTrack(beatRef.current.track);
-        beatRef.current?.stop();
-        beatRef.current = null;
-        setPlayingBeat(false);
-      } else {
-        await room.startAudio().catch(() => {});
-        const handle = startBeat();
-        beatRef.current = handle;
-        await room.localParticipant.publishTrack(handle.track, { name: 'podman-beat' });
-        setPlayingBeat(true);
-      }
+      await runBeat();
     } catch (e) {
       setNote(`Audio test failed: ${(e as Error).message}`);
     }
@@ -328,9 +313,9 @@ export function PodView({
                 </div>
 
                 <div className="grid grid-cols-2 gap-2 sm:flex sm:items-center">
-                  <Button variant="outline" onClick={toggleBeat} disabled={!room}>
+                  <Button variant="outline" onClick={onToggleBeat} disabled={!room}>
                     <Volume2Icon data-icon="inline-start" />
-                    {playingBeat ? 'Stop audio' : 'Test audio'}
+                    {beat.on ? (beat.mine ? 'Stop audio' : `Stop (${beat.by})`) : 'Test audio'}
                   </Button>
                   <Button onClick={toggleScreen} disabled={!room}>
                     <MonitorUpIcon data-icon="inline-start" />
@@ -508,7 +493,7 @@ export function PodView({
                   <CardContent>
                     <LiveWaveform
                       processing={!!room}
-                      active={false}
+                      active={beat.on}
                       height={32}
                       barWidth={2}
                       barGap={3}
@@ -517,7 +502,12 @@ export function PodView({
                     <div className="flex flex-col gap-3">
                       <StatusLine label="LiveKit" value={room ? 'connected' : 'offline'} />
                       <StatusLine label="Screen" value={sharing ? 'published' : 'not shared'} />
-                      <StatusLine label="Audio" value={playingBeat ? 'publishing' : 'ready'} />
+                      <StatusLine
+                        label="Audio"
+                        value={
+                          beat.on ? (beat.mine ? 'publishing' : `${beat.by} playing`) : 'ready'
+                        }
+                      />
                       <StatusLine label="Agent" value={podmanPresent ? 'watching' : 'waiting'} />
                     </div>
                   </CardContent>

frontend/src/livekit/useBeat.ts

@@ -0,0 +1,150 @@
+import { useCallback, useEffect, useRef, useState } from 'react';
+import { RoomEvent, type Room } from 'livekit-client';
+import { DATA_TOPIC, type DataMessage } from '@podman/shared';
+import { startBeat, type BeatHandle } from '../lib/beat.js';
+
+/** Name of the test-audio track; its presence in the room IS the shared state. */
+export const BEAT_TRACK = 'podman-beat';
+
+export interface BeatState {
+  /** Is the test audio playing anywhere in the pod? */
+  on: boolean;
+  /** Display name of the participant who started it (the owner). */
+  by: string | null;
+  /** Do I own the beat track (so I can stop it directly)? */
+  mine: boolean;
+}
+
+const OFF: BeatState = { on: false, by: null, mine: false };
+
+/**
+ * Shared, pod-wide test audio. One participant publishes the `podman-beat`
+ * track; everyone hears it and sees the same on/off state, derived directly
+ * from the track's presence (self-syncing across joins/leaves). Any participant
+ * can stop it: non-owners send BEAT_STOP and the owner unpublishes.
+ */
+export function useBeat(room: Room | null) {
+  const [beat, setBeat] = useState<BeatState>(OFF);
+  const beatRef = useRef<BeatHandle | null>(null);
+
+  const stopLocal = useCallback(async () => {
+    const handle = beatRef.current;
+    if (!handle) return;
+    beatRef.current = null;
+    try {
+      await room?.localParticipant.unpublishTrack(handle.track);
+    } finally {
+      handle.stop();
+    }
+  }, [room]);
+
+  // Derive the shared state from the podman-beat track across all participants.
+  useEffect(() => {
+    if (!room) {
+      setBeat(OFF);
+      return;
+    }
+    const recompute = () => {
+      const lp = room.localParticipant;
+      const localPub = [...lp.trackPublications.values()].find((p) => p.trackName === BEAT_TRACK);
+      if (localPub) {
+        setBeat({ on: true, by: lp.name || lp.identity, mine: true });
+        return;
+      }
+      for (const p of room.remoteParticipants.values()) {
+        const pub = [...p.trackPublications.values()].find((tp) => tp.trackName === BEAT_TRACK);
+        if (pub) {
+          setBeat({ on: true, by: p.name || p.identity, mine: false });
+          return;
+        }
+      }
+      setBeat(OFF);
+    };
+
+    recompute();
+    const events = [
+      RoomEvent.LocalTrackPublished,
+      RoomEvent.LocalTrackUnpublished,
+      RoomEvent.TrackPublished,
+      RoomEvent.TrackUnpublished,
+      RoomEvent.TrackSubscribed,
+      RoomEvent.TrackUnsubscribed,
+      RoomEvent.ParticipantConnected,
+      RoomEvent.ParticipantDisconnected,
+    ] as const;
+    events.forEach((e) => room.on(e, recompute));
+    return () => {
+      events.forEach((e) => room.off(e, recompute));
+    };
+  }, [room]);
+
+  // The owner honors stop requests from any participant.
+  useEffect(() => {
+    if (!room) return;
+    const onData = (payload: Uint8Array, _p: unknown, _k: unknown, topic?: string) => {
+      if (topic !== DATA_TOPIC) return;
+      let msg: DataMessage;
+      try {
+        msg = JSON.parse(new TextDecoder().decode(payload)) as DataMessage;
+      } catch {
+        return;
+      }
+      if (msg.type === 'BEAT_STOP') void stopLocal();
+    };
+    room.on(RoomEvent.DataReceived, onData);
+    return () => {
+      room.off(RoomEvent.DataReceived, onData);
+    };
+  }, [room, stopLocal]);
+
+  // Tear down my own track on unmount (e.g. leaving the pod).
+  const stopLocalRef = useRef(stopLocal);
+  stopLocalRef.current = stopLocal;
+  const startingRef = useRef(false);
+  const unmountedRef = useRef(false);
+  useEffect(() => {
+    return () => {
+      unmountedRef.current = true;
+      void stopLocalRef.current();
+    };
+  }, []);
+
+  const toggleBeat = useCallback(async () => {
+    if (!room) return;
+    // `beatRef` is the synchronous source of truth for "do I own it" — `beat.mine`
+    // lags behind the LiveKit track events that recompute it, so gate on the ref.
+    if (beatRef.current) {
+      await stopLocal();
+      return;
+    }
+    if (beat.on) {
+      // Someone else owns it — can't unpublish their track, so ask them to stop.
+      await room.startAudio().catch(() => {});
+      await room.localParticipant.publishData(
+        new TextEncoder().encode(JSON.stringify({ type: 'BEAT_STOP' } satisfies DataMessage)),
+        { reliable: true, topic: DATA_TOPIC },
+      );
+      return;
+    }
+    // Start it. Guard against rapid double-clicks publishing two tracks before the
+    // LocalTrackPublished event has had a chance to update state.
+    if (startingRef.current) return;
+    startingRef.current = true;
+    try {
+      await room.startAudio().catch(() => {}); // unlock playback from this gesture
+      if (unmountedRef.current) return;
+      const handle = startBeat();
+      beatRef.current = handle;
+      await room.localParticipant.publishTrack(handle.track, { name: BEAT_TRACK });
+      if (unmountedRef.current) await stopLocal(); // left mid-publish — clean up
+    } catch (e) {
+      beatRef.current?.stop();
+      beatRef.current = null;
+      throw e;
+    } finally {
+      startingRef.current = false;
+    }
+  }, [room, beat, stopLocal]);
+
+  return { beat, toggleBeat };
+}

shared/src/messages.ts

@@ -10,7 +10,9 @@ export type DataMessage =
   | { type: 'HERMES_MESSAGE'; message: HermesMessage }
   | { type: 'VOICE_CUE'; text: string }
   | { type: 'ACK'; interventionId: string; status: InterventionStatus; note?: string }
-  | { type: 'GIT_REPORT'; report: LocalGitReport };
+  | { type: 'GIT_REPORT'; report: LocalGitReport }
+  /** Any participant → the current test-audio owner: stop publishing the shared beat. */
+  | { type: 'BEAT_STOP' };
 
 /** A targeted teammate/project-channel notification from the Hermes action layer. */
 export interface HermesMessage {