fix(profile): move the now-playing channel description with the bot (#159)

When the bot was moved to another channel, the channel it left kept the
now-playing description forever: updateChannelDescription always targeted
getChannelId(), which by then already reported the new channel.

Remember which channel we last wrote to. On a self clientMoved event,
clear that channel and, if a song is playing, write the description to
the new one. Stop now clears the channel we actually wrote to, so a
missed move event can't leave a stale description behind either.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/bot/instance.ts

@@ -456,11 +456,16 @@ export class BotInstance extends EventEmitter {
       this.voiceDucking.removeSpeaker(event.id);
       void this.refreshOccupancy();
     });
-    this.tsClient.on("clientMoved", (event: { id: number }) => {
+    this.tsClient.on("clientMoved", (event: { id: number; targetChannelID: bigint }) => {
       if (event.id === this.tsClient.getClientId()) {
         // Moving the bot invalidates every activity deadline from its old
         // channel even if no individual leave events arrive.
         this.voiceDucking.reset(false);
+        // Carry the now-playing channel description over to the new
+        // channel instead of leaving it stale in the old one (#159).
+        this.profileManager.onChannelMoved(event.targetChannelID).catch((err) => {
+          this.logger.warn({ err }, "Channel description move update failed");
+        });
       } else {
         this.voiceDucking.removeSpeaker(event.id);
       }

src/bot/profile.test.ts

@@ -202,3 +202,65 @@ describe("BotProfileManager loadCustomAvatar (pre-connect load, #148)", () => {
     expect(ts.uploadCalls[0].equals(Buffer.from([2, 2]))).toBe(true);
   });
 });
+
+describe("BotProfileManager channel description follows the bot (#159)", () => {
+  const cfgChannelDesc = { ...cfgOff, channelDescEnabled: true };
+  let ts: ReturnType<typeof makeMockTs> & { cid: bigint };
+  let channelEdits: () => string[];
+
+  beforeEach(() => {
+    ts = makeMockTs() as any;
+    ts.cid = 5n;
+    (ts as any).getChannelId = () => ts.cid;
+    channelEdits = () =>
+      (ts.sendCommandNoWait as any).mock.calls
+        .map((c: any[]) => c[0] as string)
+        .filter((cmd: string) => cmd.startsWith("channeledit"));
+  });
+
+  it("clears the old channel and fills the new one when moved while playing", async () => {
+    const pm = new BotProfileManager(ts as any, noopLogger, cfgChannelDesc, "Bot");
+    await pm.onSongChange(fakeSong);
+    expect(channelEdits()).toEqual([
+      expect.stringMatching(/^channeledit cid=5 channel_description=\S+/),
+    ]);
+
+    ts.cid = 9n;
+    await pm.onChannelMoved(9n);
+
+    const edits = channelEdits();
+    expect(edits[1]).toBe("channeledit cid=5 channel_description=");
+    expect(edits[2]).toMatch(/^channeledit cid=9 channel_description=\S+/);
+  });
+
+  it("stopping after a move clears the channel the bot is in now, not the old one", async () => {
+    const pm = new BotProfileManager(ts as any, noopLogger, cfgChannelDesc, "Bot");
+    await pm.onSongChange(fakeSong);
+    ts.cid = 9n;
+    await pm.onChannelMoved(9n);
+    await pm.onSongChange(null);
+    expect(channelEdits().at(-1)).toBe("channeledit cid=9 channel_description=");
+  });
+
+  it("a move while idle touches no channel description", async () => {
+    const pm = new BotProfileManager(ts as any, noopLogger, cfgChannelDesc, "Bot");
+    ts.cid = 9n;
+    await pm.onChannelMoved(9n);
+    expect(channelEdits()).toEqual([]);
+  });
+
+  it("a move is ignored when the channel description feature is off", async () => {
+    const pm = new BotProfileManager(ts as any, noopLogger, cfgOff, "Bot");
+    await pm.onSongChange(fakeSong);
+    ts.cid = 9n;
+    await pm.onChannelMoved(9n);
+    expect(channelEdits()).toEqual([]);
+  });
+
+  it("an event for the channel the description is already in is a no-op", async () => {
+    const pm = new BotProfileManager(ts as any, noopLogger, cfgChannelDesc, "Bot");
+    await pm.onSongChange(fakeSong);
+    await pm.onChannelMoved(5n);
+    expect(channelEdits()).toHaveLength(1);
+  });
+});

src/bot/profile.ts

@@ -32,6 +32,13 @@ export class BotProfileManager {
    * pushed immediately (idle) or wait for the next stop event (playing).
    */
   private currentSong: QueuedSong | null = null;
+  /**
+   * Channel whose description currently holds our now-playing text, or null
+   * if we have not written one. Remembered so that when the bot is moved we
+   * can still clean up the channel it was taken out of (#159) — by then
+   * getChannelId() already reports the new channel.
+   */
+  private channelDescCid: bigint | null = null;
 
   /** Per-feature permission-denied flags. Reset on reconnect. */
   private permDenied = {
@@ -134,6 +141,8 @@ export class BotProfileManager {
   onConnect(): void {
     this.generation++;
     this.currentSong = null;
+    // Channel ids are per-server; never carry one across a (re)connect.
+    this.channelDescCid = null;
     this.permDenied = {
       avatar: false,
       description: false,
@@ -150,6 +159,31 @@ export class BotProfileManager {
     }
   }
 
+  /**
+   * Called when the bot itself has been moved to another channel (#159).
+   * Clears the now-playing text from the channel it left and, if a song is
+   * playing, writes it to the channel it is in now.
+   */
+  async onChannelMoved(newChannelId: bigint): Promise<void> {
+    if (!this.config.channelDescEnabled || this.permDenied.channelDesc) return;
+    const oldChannelId = this.channelDescCid;
+    if (oldChannelId === newChannelId) return;
+    try {
+      if (oldChannelId !== null) {
+        await this.tsClient.sendCommandNoWait(
+          `channeledit cid=${oldChannelId} channel_description=`,
+        );
+        this.channelDescCid = null;
+      }
+    } catch (err) {
+      this.handleFeatureError("channelDesc", err);
+      return;
+    }
+    if (this.currentSong) {
+      await this.updateChannelDescription(this.currentSong, newChannelId);
+    }
+  }
+
   getConfig(): ProfileConfig {
     return { ...this.config };
   }
@@ -400,18 +434,25 @@ export class BotProfileManager {
     return str.slice(0, end) + ellipsis;
   }
 
-  private async updateChannelDescription(song: QueuedSong | null): Promise<void> {
+  private async updateChannelDescription(
+    song: QueuedSong | null,
+    targetChannelId?: bigint,
+  ): Promise<void> {
     if (!this.config.channelDescEnabled || this.permDenied.channelDesc) return;
     try {
-      const channelId = this.tsClient.getChannelId();
-      if (channelId === 0n) return; // unknown channel
-
+      const channelId = targetChannelId ?? this.tsClient.getChannelId();
       if (!song) {
+        // Prefer the channel we actually wrote to, in case a move event
+        // was missed and the bot is somewhere else now.
+        const target = this.channelDescCid ?? channelId;
+        if (target === 0n) return; // unknown channel
         await this.tsClient.sendCommandNoWait(
-          `channeledit cid=${channelId} channel_description=`,
+          `channeledit cid=${target} channel_description=`,
         );
+        this.channelDescCid = null;
         return;
       }
+      if (channelId === 0n) return; // unknown channel
 
       const lines = [
         `\u266A \u6B63\u5728\u64AD\u653E: ${song.name} - ${song.artist}`, // ♪ 正在播放:
@@ -422,6 +463,7 @@ export class BotProfileManager {
       await this.tsClient.sendCommandNoWait(
         `channeledit cid=${channelId} channel_description=${escapeTS3(desc)}`,
       );
+      this.channelDescCid = channelId;
     } catch (err) {
       this.handleFeatureError("channelDesc", err);
     }