Count listeners from the room so the bot leaves empty channels

The bot stayed in a channel everyone had left. revoice.js stores voice
users by participant identity but removes them by participant name — and
Stoat sets those to different things (the user id and username#tag) — so
its list never shrinks and the channel never looked empty to us.

Participants are now counted from the LiveKit room directly, and the
check also runs on a 30s interval, so a participant event that never
arrives cannot strand the bot either.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/player.ts

@@ -80,6 +80,7 @@ export class GuildPlayer extends EventEmitter<GuildPlayerEvents> {
   /** Set while we tear playback down ourselves, so the resulting `finish` is ignored. */
   private expectingStop = false;
   private leaveTimer: NodeJS.Timeout | null = null;
+  private presenceTimer: NodeJS.Timeout | null = null;
   private ticker: NodeJS.Timeout | null = null;
   private readonly log;
 
@@ -214,11 +215,19 @@ export class GuildPlayer extends EventEmitter<GuildPlayerEvents> {
 
     this.setStatus("idle");
     this.checkEmptyChannel();
+    // Belt and braces: a participant event we never receive would otherwise
+    // leave the bot sitting in an empty channel indefinitely.
+    this.presenceTimer = setInterval(() => this.checkEmptyChannel(), 30_000);
+    this.presenceTimer.unref?.();
     this.log.info({ channelId }, "voice connection established");
   }
 
   async leaveVoice(): Promise<void> {
     this.cancelLeaveTimer();
+    if (this.presenceTimer) {
+      clearInterval(this.presenceTimer);
+      this.presenceTimer = null;
+    }
     this.stopScreenShare();
     this.stopTicker();
     this.teardownPlayback();
@@ -244,9 +253,19 @@ export class GuildPlayer extends EventEmitter<GuildPlayerEvents> {
     this.publish();
   }
 
+  /**
+   * Counted straight from the LiveKit room. revoice's own list cannot be
+   * trusted: it stores users by participant identity but removes them by
+   * participant name, so nobody is ever dropped and the channel never looks
+   * empty — the bot would sit in it forever.
+   */
+  private listenersInChannel(): number {
+    return this.connection?.room?.remoteParticipants?.size ?? 0;
+  }
+
   private checkEmptyChannel(): void {
     if (!this.connection) return;
-    if (this.connection.getUsers().length > 0) {
+    if (this.listenersInChannel() > 0) {
       this.cancelLeaveTimer();
       return;
     }
@@ -549,7 +568,7 @@ export class GuildPlayer extends EventEmitter<GuildPlayerEvents> {
     this.cancelLeaveTimer();
     if (config.EMPTY_TIMEOUT_SECONDS <= 0 || !this.connection) return;
     this.leaveTimer = setTimeout(() => {
-      if (this.connection && this.connection.getUsers().length > 0) return;
+      if (this.listenersInChannel() > 0) return;
       this.notify("👋 В канале никого не осталось, выхожу.");
       void this.leaveVoice();
     }, config.EMPTY_TIMEOUT_SECONDS * 1000);