Show TTS provider in toast, support full LiteLLM model paths

- TTS response now includes X-TTS-Provider header (google-tts, litellm/model, elevenlabs)
- Frontend reads header and shows actual provider in toast instead of hardcoded "Adam/ElevenLabs"
- CORS exposes X-TTS-Provider header so frontend can access it
- Updated .env.example: clarify that LITELLM_TTS_MODEL and LITELLM_STT_MODEL
  can be either the model_name alias OR the full provider/model path depending
  on your LiteLLM config (important for BAA compliance routing)

.env.example

@@ -44,14 +44,17 @@ OPENROUTER_API_KEY=sk-or-v1-your-key
 #
 # LiteLLM Speech-to-Text
 # TRANSCRIBE_PROVIDER=litellm
-# LITELLM_STT_MODEL=whisper-1             # model_name alias in LiteLLM config
+# LITELLM_STT_MODEL=whisper-1             # Use the model name from your LiteLLM model_list
+#   If your LiteLLM config uses full paths as model names, use the full path:
+#   LITELLM_STT_MODEL=openai/whisper-1
 # NOTE: vertex_ai/chirp does NOT work via LiteLLM audio proxy.
 # For Vertex AI speech, use TRANSCRIBE_PROVIDER=google (Gemini inline audio).
 #
-# LiteLLM TTS: WORKS — use the model_name alias from your LiteLLM model_list
+# LiteLLM TTS
 # TTS_PROVIDER=litellm                  (auto-detected when LITELLM_API_BASE set)
-# LITELLM_TTS_MODEL=tts-1               # model_name alias in LiteLLM config
+# LITELLM_TTS_MODEL=tts-1               # Use model name from your LiteLLM model_list
-# LITELLM_TTS_VOICE=en-US-Journey-F     # passed to LiteLLM, supports Google Cloud voice names
+#   If your config uses full paths: LITELLM_TTS_MODEL=vertex_ai/google-tts
+# LITELLM_TTS_VOICE=en-US-Journey-F     # Google Cloud voice name (or alloy/nova for OpenAI)
 
 # ============================================================
 # TRANSCRIPTION (speech-to-text)

public/js/app.js

@@ -389,20 +389,21 @@ function speakText(elementId) {
   })
   .then(function(r) {
     if (!r.ok) throw new Error('TTS request failed (' + r.status + ')');
-    return r.blob();
+    var ttsProvider = r.headers.get('X-TTS-Provider') || 'server';
+    return r.blob().then(function(blob) { return { blob: blob, provider: ttsProvider }; });
   })
-  .then(function(blob) {
+  .then(function(result) {
-    var url = URL.createObjectURL(blob);
+    var url = URL.createObjectURL(result.blob);
     currentAudio = new Audio(url);
     currentAudio.onended = function() { URL.revokeObjectURL(url); stopReading(); };
     currentAudio.onerror = function() { URL.revokeObjectURL(url); stopReading(); showToast('Audio playback error', 'error'); };
     currentAudio.play();
     if (btn) { btn.classList.add('btn-reading'); btn.innerHTML = '<i class="fas fa-stop"></i> Stop'; }
-    showToast('Reading aloud (Adam/ElevenLabs)', 'info');
+    showToast('Reading aloud (' + result.provider + ')', 'info');
   })
   .catch(function(err) {
     stopReading();
-    // Fallback to browser TTS if ElevenLabs fails
+    // Fallback to browser TTS if server TTS fails
     if ('speechSynthesis' in window) {
       var utter = new SpeechSynthesisUtterance(text);
       utter.rate = 0.9;

server.js

@@ -46,7 +46,8 @@ app.use(cors({
     if (origin === allowedOrigin) return callback(null, true);
     callback(new Error('CORS: origin not allowed'));
   },
-  credentials: true
+  credentials: true,
+  exposedHeaders: ['X-TTS-Provider']
 }));
 
 app.use(cookieParser());

src/routes/tts.js

@@ -34,13 +34,14 @@ router.post('/text-to-speech', authMiddleware, async (req, res) => {
     if (ttsProvider === 'google') {
       var buffer = await synthesizeWithGoogleTTS(text);
       res.set('Content-Type', 'audio/mpeg');
+      res.set('X-TTS-Provider', 'google-tts');
       return res.send(buffer);
     }
 
     if (ttsProvider === 'litellm') {
       if (!process.env.LITELLM_API_BASE) return res.status(400).json({ error: 'LITELLM_API_BASE not set.' });
-      // Model must be the model_name alias from LiteLLM model_list (e.g. tts-1, tts-1-hd)
+      // Use the full model path (e.g. vertex_ai/google-tts) or the model_name alias
-      // NOT the underlying vertex_ai/... path — LiteLLM routes by alias
+      // from your LiteLLM model_list. Full path is safer if your config uses it directly.
       var ttsModel   = process.env.LITELLM_TTS_MODEL || 'tts-1';
       var ttsVoice   = process.env.LITELLM_TTS_VOICE || 'en-US-Journey-F';
       var base       = process.env.LITELLM_API_BASE.replace(/\/+$/, '');
@@ -51,6 +52,7 @@ router.post('/text-to-speech', authMiddleware, async (req, res) => {
         { headers: ttsHeaders, responseType: 'arraybuffer', timeout: 60000 }
       );
       res.set('Content-Type', 'audio/mpeg');
+      res.set('X-TTS-Provider', 'litellm/' + ttsModel);
       return res.send(Buffer.from(ttsResp.data));
     }
 
@@ -64,6 +66,7 @@ router.post('/text-to-speech', authMiddleware, async (req, res) => {
         responseType: 'arraybuffer'
       });
       res.set('Content-Type', 'audio/mpeg');
+      res.set('X-TTS-Provider', 'elevenlabs');
       return res.send(Buffer.from(resp.data));
     }