feat(tts): dedicated ATIS broadcast voice on Speaches

The ATIS tag now resolves to en_GB-alba-medium — outside both voice pools —
instead of sharing 'verse' with the user's own readback voice.

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

server/api/atc/say.post.ts

@@ -212,7 +212,7 @@ export default defineEventHandler(async (event) => {
         voice,
     };
     const speachesVoice = provider === "speaches"
-        ? resolveSpeachesVoice(voice, speachesFallback)
+        ? resolveSpeachesVoice(voice, speachesFallback, body?.tag)
         : null;
     const ttsVoice = speachesVoice?.voice ?? voice;
     const providerModel = speachesVoice

server/utils/voiceRegistry.test.ts

@@ -28,6 +28,14 @@ describe('resolveSpeachesVoice', () => {
     assert.deepEqual(resolveSpeachesVoice('', fallback), fallback)
   })
 
+  it('gives the ATIS broadcast its own dedicated speaker', () => {
+    const atis = resolveSpeachesVoice('verse', fallback, 'atis')
+    assert.match(atis.voice, /^en_/)
+    assert.notEqual(atis.voice, resolveSpeachesVoice('verse', fallback).voice)
+    const allPoolVoices = Object.values(SPEACHES_VOICE_MAP).map(v => v.voice)
+    assert.equal(allPoolVoices.includes(atis.voice), false, 'ATIS voice must not be in any pool')
+  })
+
   it('keeps controller and pilot voices audibly disjoint', () => {
     const controller = ['alloy', 'echo', 'onyx', 'sage'].map(v => resolveSpeachesVoice(v, fallback).voice)
     const pilots = ['verse', 'ash', 'ballad', 'coral', 'fable', 'nova', 'shimmer']

server/utils/voiceRegistry.ts

@@ -34,7 +34,18 @@ export const SPEACHES_VOICE_MAP: Record<string, SpeachesVoice> = {
   shimmer: piper('en_US-kristin-medium'),
 }
 
-export function resolveSpeachesVoice(logical: string, fallback: SpeachesVoice): SpeachesVoice {
+/**
+ * ATIS is a robotic broadcast in the real world — it gets a dedicated speaker
+ * outside every pool so it never sounds like a controller or a pilot.
+ */
+export const ATIS_SPEACHES_VOICE: SpeachesVoice = piper('en_GB-alba-medium')
+
+export function resolveSpeachesVoice(
+  logical: string,
+  fallback: SpeachesVoice,
+  tag?: string,
+): SpeachesVoice {
+  if ((tag || '').trim().toLowerCase() === 'atis') return ATIS_SPEACHES_VOICE
   const key = (logical || '').trim().toLowerCase()
   return SPEACHES_VOICE_MAP[key] ?? fallback
 }