feat(commands): play a bonk sound on the bonked user's rover

`rs bonk` now publishes a `fun.bonked` event carrying the rover the target is
currently driving, and a new audioForwardService listener plays a sound file on
it. Wired as an event rather than a direct call so the command layer stays
unaware of ffmpeg, matching how the charging-complete cue is already done.

The sound file goes at `server/assets/bonk.wav` and is NOT committed here. Note
that `server/assets` is the correct home rather than `server/public`: the webui
builds to `../server/public` with `emptyOutDir: true`, so anything stored there
is deleted by the next build.

Details:

- The audio is rate limited per rover on a 20s window, separate from the 4s text
  cooldown. Playback interrupts whatever that rover is forwarding, including a
  live microphone, so a group of people cannot chain it against one driver.
- No sound plays if the target is not currently driving, is not a real user, or
  is the caller themselves. The text bonk and the tally still work in all cases.
- A missing sound file logs once and skips, so the command works on a server that
  never installs one. A playback failure is caught and logged rather than
  surfacing as a failed chat command.
- Discord bonks play the sound too; only commands needing the caller's own socket
  are unavailable from there.

Server suite: 138 passing, 0 failing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

server/src/services/audioForwardService/bonkSound.js

@@ -0,0 +1,55 @@
+// audio Forward Service bonk sound
+// Purpose: Plays the built-in bonk sound effect on the rover a bonked user is driving.
+// Scope: Keeps the fun commands and the audio pipeline decoupled by listening to the server event bus only.
+const path = require('path');
+const fs = require('fs');
+const { subscribe } = require('../eventBus');
+
+/*
+  Lives in server/assets rather than server/public because the webui build writes
+  to server/public with emptyOutDir enabled, which deletes anything else in there.
+  server/assets is a plain checked-in asset directory that no build step touches.
+*/
+const BONK_SOUND_PATH = path.resolve(__dirname, '..', '..', '..', 'assets', 'bonk.wav');
+
+function registerBonkSound(deps) {
+  const {
+    logger,
+    playServerAudioFile,
+    soundPath = BONK_SOUND_PATH,
+  } = deps;
+
+  subscribe('fun.bonked', (event = {}) => {
+    const roverId = String(event?.payload?.roverId || '').trim();
+    if (!roverId) return;
+
+    /*
+      The sound is optional. An operator who has not dropped a bonk.wav into
+      server/assets still gets a fully working `rs bonk` command, so a missing
+      file is reported once at debug volume rather than thrown at the caller.
+    */
+    if (!fs.existsSync(soundPath)) {
+      logger.info('Bonk sound file is not installed; skipping playback', { soundPath });
+      return;
+    }
+
+    try {
+      playServerAudioFile(roverId, soundPath, { source: 'bonk' });
+      logger.info('Played bonk sound', { roverId, soundPath });
+    } catch (err) {
+      // Playback interrupts mic forwarding and spawns ffmpeg, so an offline rover
+      // or a missing encoder must not turn into a failed chat command. The bonk
+      // itself already happened; the sound is layered on top of it.
+      logger.warn('Failed to play bonk sound', {
+        roverId,
+        soundPath,
+        error: err?.message || String(err),
+      });
+    }
+  });
+}
+
+module.exports = {
+  registerBonkSound,
+  BONK_SOUND_PATH,
+};

server/src/services/audioForwardService/bonkSound.test.js

@@ -0,0 +1,84 @@
+// audio Forward Service bonk sound tests
+// Purpose: Verifies the bonk cue plays for a real event and stays contained when the file or rover is missing.
+// Scope: Subscribes through the real event bus with a playback double; no ffmpeg runs.
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+const { publishEvent } = require('../eventBus');
+const { registerBonkSound, BONK_SOUND_PATH } = require('./bonkSound');
+
+const soundDir = fs.mkdtempSync(path.join(os.tmpdir(), 'bonk-sound-test-'));
+const presentSound = path.join(soundDir, 'bonk.wav');
+fs.writeFileSync(presentSound, 'not really audio, only the path is read here');
+const missingSound = path.join(soundDir, 'absent.wav');
+
+function harness({ soundPath = presentSound, playImpl = null } = {}) {
+  const played = [];
+  const warnings = [];
+  registerBonkSound({
+    logger: {
+      info: () => {},
+      warn: (message, meta) => warnings.push({ message, meta }),
+    },
+    playServerAudioFile: (roverId, filePath, options) => {
+      played.push({ roverId, filePath, options });
+      if (playImpl) playImpl();
+    },
+    soundPath,
+  });
+  return { played, warnings };
+}
+
+// Each registerBonkSound call adds another subscriber to the shared bus, so every
+// test publishes a distinct rover id and asserts only on its own rover.
+function bonk(roverId) {
+  publishEvent({ source: 'test', type: 'fun.bonked', payload: { roverId, targetLabel: 'bob' } });
+}
+
+test('a bonk event plays the sound on the named rover', () => {
+  const { played } = harness();
+  bonk('rover-play');
+
+  const mine = played.filter((entry) => entry.roverId === 'rover-play');
+  assert.equal(mine.length, 1);
+  assert.equal(mine[0].filePath, presentSound);
+  assert.equal(mine[0].options.source, 'bonk');
+});
+
+test('an event with no rover id is ignored', () => {
+  const { played } = harness();
+  publishEvent({ source: 'test', type: 'fun.bonked', payload: {} });
+  publishEvent({ source: 'test', type: 'fun.bonked', payload: { roverId: '   ' } });
+  assert.equal(played.length, 0);
+});
+
+test('a missing sound file skips playback instead of throwing', () => {
+  const { played, warnings } = harness({ soundPath: missingSound });
+  assert.doesNotThrow(() => bonk('rover-missing'));
+  assert.equal(played.filter((entry) => entry.roverId === 'rover-missing').length, 0);
+  assert.equal(warnings.length, 0, 'a not-installed sound is informational, not a warning');
+});
+
+test('a playback failure is contained and logged rather than thrown at the caller', () => {
+  const { warnings } = harness({
+    playImpl: () => {
+      throw new Error('Rover offline');
+    },
+  });
+  assert.doesNotThrow(() => bonk('rover-offline'));
+  assert.ok(warnings.some((entry) => entry.meta?.error === 'Rover offline'));
+});
+
+test('the default sound path lives in server/assets, which the webui build does not wipe', () => {
+  // webui/vite.config.js builds to ../server/public with emptyOutDir enabled, so a
+  // sound stored there would be deleted by the next build.
+  assert.match(BONK_SOUND_PATH, /server\/assets\/bonk\.wav$/);
+  assert.doesNotMatch(BONK_SOUND_PATH, /server\/public/);
+});
+
+test.after(() => {
+  fs.rmSync(soundDir, { recursive: true, force: true });
+});

server/src/services/audioForwardService/index.js

@@ -14,6 +14,7 @@ const { createAudioForwardPolicy } = require('./policy');
 const { createAudioForwardWorkerEngine } = require('./workerEngine');
 const { registerAudioForwardHooks } = require('./hooks');
 const { registerChargeCompleteSound } = require('./chargeCompleteSound');
+const { registerBonkSound } = require('./bonkSound');
 
 const audioForwardEvents = new EventEmitter();
 const config = loadConfig();
@@ -151,6 +152,11 @@ registerChargeCompleteSound({
   playServerAudioFile,
 });
 
+registerBonkSound({
+  logger,
+  playServerAudioFile,
+});
+
 module.exports = {
   getAudioForwardState,
   audioForwardEvents,