feat(classroom): use local speech bridge for instructor TTS when available

Mirrors the local-first routing live-atc already has via useRadioSpeech.ts:
requestSayAudio now tries a locally running Speech Bridge (127.0.0.1:8765-8770)
before falling back to the cloud /api/atc/say endpoint.

app/pages/classroom.vue

@@ -1487,6 +1487,7 @@ import {
 import {DEFAULT_AIRLINE_TELEPHONY, normalizeRadioPhrase, normalizeMetarPhrase} from '~~/shared/utils/radioSpeech'
 import {denormalizeSpokenAtc, looksLikeCallsignKey, normalizeForMatch} from '~~/shared/utils/sttMatch'
 import {useBugReport} from '~/composables/useBugReport'
+import {postWithLocalFallback, useLocalSpeechBridge} from '~/composables/useLocalSpeechBridge'
 import BugReportDialog from '~/components/BugReportDialog.vue'
 
 definePageMeta({middleware: ['require-auth', 'require-classroom-intro']})
@@ -2850,6 +2851,7 @@ const promptReplayCount = ref(0)
 const replaySpeedHintSeen = ref(false)
 
 const api = useApi()
+const {localUrl} = useLocalSpeechBridge()
 const isClient = typeof window !== 'undefined'
 const auth = useAuthStore()
 
@@ -4327,7 +4329,11 @@ async function requestSayAudio(cacheKey: string, payload: Record<string, unknown
   }
 
   const request = (async () => {
-    const response: any = await api.post('/api/atc/say', payload)
+    const response: any = await postWithLocalFallback(
+      localUrl('/api/atc/say'),
+      payload,
+      () => api.post('/api/atc/say', payload),
+    )
     const audioData = response?.audio
     if (!audioData?.base64) {
       throw new Error('Missing audio data')

docs/plans/2026-07-29-classroom-local-bridge.md

@@ -0,0 +1,90 @@
+# Classroom Local Speech Bridge Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Make classroom mode's instructor TTS use a locally running Speech Bridge when one is reachable, falling back to the existing cloud `/api/atc/say` path otherwise — same behavior live-atc already has.
+
+**Architecture:** Reuse the existing `app/composables/useLocalSpeechBridge.ts` composable unchanged. Wire its `useLocalSpeechBridge()` probe and `postWithLocalFallback()` helper into classroom's single TTS call site (`requestSayAudio` in `app/pages/classroom.vue`), mirroring exactly how `app/composables/useRadioSpeech.ts` already does it for live-atc.
+
+**Tech Stack:** Vue 3 `<script setup>` SFC, Vitest.
+
+---
+
+### Task 1: Wire the local bridge into classroom's TTS request
+
+**Files:**
+- Modify: `app/pages/classroom.vue` (imports near line 1489, `api` setup near line 2852, `requestSayAudio` at line 4323-4354)
+- Test (already exists, unaffected — confirms the wiring re-uses the same tested primitive): `app/composables/useRadioSpeech.localRouting.test.ts`
+
+**Step 1: Add the import**
+
+In `app/pages/classroom.vue`, after the existing `useBugReport` import (line 1489):
+
+```ts
+import { postWithLocalFallback, useLocalSpeechBridge } from '~/composables/useLocalSpeechBridge'
+```
+
+**Step 2: Initialize the bridge probe alongside `api`**
+
+Near line 2852, change:
+
+```ts
+const api = useApi()
+```
+
+to:
+
+```ts
+const api = useApi()
+const { localUrl } = useLocalSpeechBridge()
+```
+
+**Step 3: Route the TTS request through the local bridge with cloud fallback**
+
+In `requestSayAudio` (`app/pages/classroom.vue:4323-4343`), replace:
+
+```ts
+  const request = (async () => {
+    const response: any = await api.post('/api/atc/say', payload)
+    const audioData = response?.audio
+```
+
+with:
+
+```ts
+  const request = (async () => {
+    const response: any = await postWithLocalFallback(
+      localUrl('/api/atc/say'),
+      payload,
+      () => api.post('/api/atc/say', payload),
+    )
+    const audioData = response?.audio
+```
+
+Leave the rest of `requestSayAudio` (lines ~4331-4343) untouched — `sayCache`/`pendingSayRequests` caching is keyed by `cacheKey` (voice/level/rate/text), not by transport, so it needs no changes.
+
+**Step 4: Typecheck**
+
+Run: `yarn typecheck`
+Expected: no new errors.
+
+**Step 5: Run the test suite**
+
+Run: `yarn test`
+Expected: all existing tests pass, including `app/composables/useRadioSpeech.localRouting.test.ts` and `tests/shared/classroomCurriculum.test.ts` (neither touches classroom.vue directly, but both must stay green — they cover the shared primitives this task reuses).
+
+**Step 6: Manual verification (no local bridge running)**
+
+Run: `yarn dev`
+Open classroom mode in the browser, trigger any instructor TTS playback (e.g. replay a prompt). Expect it to play normally via the cloud path — `localUrl('/api/atc/say')` returns `null` when no bridge is found on ports 8765-8770, so `postWithLocalFallback` calls the cloud function directly, identical to current behavior.
+
+**Step 7: Manual verification (local bridge present) — optional but recommended**
+
+Start a minimal stub server on port 8765 that responds `{ ok: true, ready: true }` on `GET /health` and returns a valid `{ audio: { base64, mime } }` shape on `POST /api/atc/say`, then reload classroom and trigger TTS again — confirm the network tab shows the request going to `127.0.0.1:8765` instead of the app's own origin. Skip this step if no bridge stub is readily available; the fallback logic itself is already covered by `useRadioSpeech.localRouting.test.ts`.
+
+**Step 8: Commit**
+
+```bash
+git add app/pages/classroom.vue
+git commit -m "feat(classroom): use local speech bridge for instructor TTS when available"
+```