Fix STT/TTS properly per LiteLLM docs

STT: Vertex AI Chirp not supported via LiteLLM proxy (confirmed by docs).
     Now uses Gemini directly (transcribeGoogle.js) — auto-detected when
     GOOGLE_VERTEX_PROJECT is set, fallback to AWS then OpenAI.

TTS: LiteLLM Vertex TTS DOES work but requires the model_list ALIAS
     (tts-1) not the underlying path (vertex_ai/text-to-speech).
     Also pass voice param — LiteLLM supports Google Cloud voice names.
     Auto-detected when LITELLM_API_BASE is set.

.env.example

@@ -26,6 +26,15 @@ OPENROUTER_API_KEY=sk-or-v1-your-key
 # GOOGLE_VERTEX_LOCATION=us-central1
 # GOOGLE_APPLICATION_CREDENTIALS=/path/to/service-account.json
 # (Or use default credentials if running on GCE/GKE/Cloud Run)
+#
+# Google STT — Gemini inline audio (auto-detected when GOOGLE_VERTEX_PROJECT set)
+# TRANSCRIBE_PROVIDER=google
+# GOOGLE_STT_MODEL=gemini-2.0-flash    # or gemini-2.5-flash for better accuracy
+#
+# Google TTS — Google Cloud Text-to-Speech (auto-detected when GOOGLE_VERTEX_PROJECT set)
+# TTS_PROVIDER=google
+# GOOGLE_TTS_VOICE=en-US-Journey-F     # female | en-US-Journey-D = male
+#   Other options: en-US-Studio-O, en-US-Neural2-C, en-US-Neural2-J
 
 # Option 5: LiteLLM Proxy (self-hosted, routes to any provider)
 # AI_PROVIDER=litellm
@@ -35,12 +44,13 @@ OPENROUTER_API_KEY=sk-or-v1-your-key
 #
 # LiteLLM Speech-to-Text (auto-enabled when LITELLM_API_BASE is set)
 # TRANSCRIBE_PROVIDER=litellm
-# LITELLM_STT_MODEL=vertex_ai/chirp    # or: vertex_ai/chirp_2 for newer model
+# LiteLLM STT: NOT supported for Vertex AI Chirp via LiteLLM proxy.
+# Use TRANSCRIBE_PROVIDER=google for Vertex AI / Gemini STT.
 #
-# LiteLLM Text-to-Speech (auto-enabled when LITELLM_API_BASE is set)
+# LiteLLM TTS: WORKS — use the model_name alias from your LiteLLM model_list
-# TTS_PROVIDER=litellm
+# TTS_PROVIDER=litellm                  (auto-detected when LITELLM_API_BASE set)
-# LITELLM_TTS_MODEL=vertex_ai/text-to-speech   # voice is set inside LiteLLM per model
+# LITELLM_TTS_MODEL=tts-1               # model_name alias in LiteLLM config
-# LITELLM_TTS_VOICE is ignored for Vertex AI — voice is configured in LiteLLM model entry
+# LITELLM_TTS_VOICE=en-US-Journey-F     # passed to LiteLLM, supports Google Cloud voice names
 
 # ============================================================
 # TRANSCRIPTION (speech-to-text)

src/routes/transcribe.js

@@ -4,32 +4,33 @@ const multer = require('multer');
 const { whisperClient, litellmClient } = require('../utils/ai');
 const { transcribeWithAWS, isAWSTranscribeConfigured } = require('../utils/transcribeAWS');
 const { transcribeWithLocal, isLocalWhisperConfigured } = require('../utils/transcribeLocal');
+const { transcribeWithGemini, isGoogleSTTConfigured } = require('../utils/transcribeGoogle');
 const { authMiddleware } = require('../middleware/auth');
 
 const upload = multer({ storage: multer.memoryStorage(), limits: { fileSize: 25 * 1024 * 1024 } });
 
-// Determine which provider to use:
+// Provider priority (auto-detect):
-// TRANSCRIBE_PROVIDER=litellm → LiteLLM proxy (any Whisper-compatible model)
+// TRANSCRIBE_PROVIDER=google → Vertex AI / Gemini (direct, HIPAA eligible)
-// TRANSCRIBE_PROVIDER=aws     → Amazon Transcribe
+// TRANSCRIBE_PROVIDER=aws    → Amazon Transcribe (HIPAA eligible)
-// TRANSCRIBE_PROVIDER=local   → local whisper.cpp / faster-whisper
+// TRANSCRIBE_PROVIDER=local  → local whisper.cpp / faster-whisper
-// TRANSCRIBE_PROVIDER=openai  → OpenAI Whisper directly
+// TRANSCRIBE_PROVIDER=openai → OpenAI Whisper (direct)
-// (auto) LITELLM_API_BASE set → litellm
+// TRANSCRIBE_PROVIDER=litellm→ LiteLLM proxy (explicit only — audio routing bugs)
-// (auto) AWS Bedrock region set → aws
+// Auto: google > aws > openai
-// (default) → openai whisper
 function getTranscribeProvider() {
   var env = process.env.TRANSCRIBE_PROVIDER;
-  if (env === 'litellm') return 'litellm';
+  if (env === 'google')  return 'google';
-  if (env === 'local')   return 'local';
   if (env === 'aws')     return 'aws';
+  if (env === 'local')   return 'local';
   if (env === 'openai')  return 'openai';
-  // Auto-detect priority: AWS > LiteLLM > OpenAI
+  if (env === 'litellm') return 'litellm';
-  // LiteLLM's Vertex AI audio proxy has routing bugs — only use it if explicitly set
+  // Auto-detect
+  if (isGoogleSTTConfigured())    return 'google';
   if (isAWSTranscribeConfigured()) return 'aws';
-  if (process.env.LITELLM_API_BASE && litellmClient) return 'litellm';
   return 'openai';
 }
 
 function isTranscribeAvailable() {
+  if (isGoogleSTTConfigured())    return true;
   if (isLocalWhisperConfigured()) return true;
   if (isAWSTranscribeConfigured()) return true;
   if (litellmClient) return true;
@@ -38,11 +39,13 @@ function isTranscribeAvailable() {
 }
 
 var provider = getTranscribeProvider();
-var medical = process.env.AWS_TRANSCRIBE_MEDICAL === 'true';
+var medical  = process.env.AWS_TRANSCRIBE_MEDICAL === 'true';
 var available = isTranscribeAvailable();
-console.log('🎙️  Transcribe provider:', provider + (provider === 'aws' && medical ? ' (Medical)' : '') + (available ? '' : ' (NOT CONFIGURED — browser speech only)'));
+console.log('🎙️  Transcribe provider:', provider +
+  (provider === 'aws' && medical ? ' (Medical)' : '') +
+  (provider === 'google' ? ' (model: ' + (process.env.GOOGLE_STT_MODEL || 'gemini-2.0-flash') + ')' : '') +
+  (available ? '' : ' (NOT CONFIGURED — browser speech only)'));
 
-// Status endpoint — frontend checks this to decide whether to upload audio
 router.get('/transcribe/status', authMiddleware, (req, res) => {
   res.json({ available: available, provider: available ? provider : 'none' });
 });
@@ -51,9 +54,15 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
   try {
     if (!req.file) return res.status(400).json({ error: 'No audio' });
     var startTime = Date.now();
-    var fileSize = req.file.size;
+    var fileSize  = req.file.size;
     console.log('[Transcribe] Received ' + (fileSize / 1024).toFixed(0) + 'KB audio (' + (req.file.mimetype || 'unknown') + ') via ' + provider);
 
+    if (provider === 'google') {
+      var text = await transcribeWithGemini(req.file.buffer, req.file.mimetype || 'audio/webm');
+      console.log('[Transcribe] Google/Gemini done in ' + (Date.now() - startTime) + 'ms');
+      return res.json({ success: true, text: text, provider: 'google-gemini', duration: Date.now() - startTime });
+    }
+
     if (provider === 'local') {
       var text = await transcribeWithLocal(req.file.buffer, req.file.mimetype || 'audio/webm');
       console.log('[Transcribe] Local done in ' + (Date.now() - startTime) + 'ms');
@@ -61,9 +70,7 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
     }
 
     if (provider === 'aws') {
-      if (!isAWSTranscribeConfigured()) {
+      if (!isAWSTranscribeConfigured()) return res.status(400).json({ error: 'AWS Transcribe not configured.' });
-        return res.status(400).json({ error: 'AWS Transcribe not configured. Set AWS_BEDROCK_REGION.' });
-      }
       var text = await transcribeWithAWS(req.file.buffer, req.file.mimetype || 'audio/webm');
       console.log('[Transcribe] AWS done in ' + (Date.now() - startTime) + 'ms');
       return res.json({ success: true, text: text, provider: 'aws-transcribe', duration: Date.now() - startTime });
@@ -73,22 +80,16 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
       if (!process.env.LITELLM_API_BASE) return res.status(400).json({ error: 'LITELLM_API_BASE not set.' });
       var sttModel = process.env.LITELLM_STT_MODEL || 'vertex_ai/chirp';
       var FormData = require('form-data');
-      var axios = require('axios');
+      var axios    = require('axios');
       var form = new FormData();
-      form.append('file', req.file.buffer, {
+      form.append('file', req.file.buffer, { filename: 'audio.webm', contentType: req.file.mimetype || 'audio/webm' });
-        filename: 'audio.webm',
-        contentType: req.file.mimetype || 'audio/webm'
-      });
       form.append('model', sttModel);
-      // Note: Vertex AI Chirp via LiteLLM does not support 'prompt' or 'response_format'
-      // Only send parameters Chirp actually accepts
       var sttHeaders = Object.assign({}, form.getHeaders());
       if (process.env.LITELLM_API_KEY) sttHeaders['Authorization'] = 'Bearer ' + process.env.LITELLM_API_KEY;
-      var base = process.env.LITELLM_API_BASE.replace(/\/+$/, '');
+      var sttResp = await require('axios').post(
-      var sttResp = await axios.post(base + '/v1/audio/transcriptions', form, {
+        process.env.LITELLM_API_BASE.replace(/\/+$/, '') + '/v1/audio/transcriptions',
-        headers: sttHeaders,
+        form, { headers: sttHeaders, timeout: 120000 }
-        timeout: 120000
+      );
-      });
       var text = (sttResp.data && sttResp.data.text) ? sttResp.data.text : String(sttResp.data || '');
       console.log('[Transcribe] LiteLLM (' + sttModel + ') done in ' + (Date.now() - startTime) + 'ms');
       return res.json({ success: true, text: text, provider: 'litellm-stt', duration: Date.now() - startTime });
@@ -96,7 +97,7 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
 
     // OpenAI Whisper (direct)
     if (!whisperClient) return res.status(400).json({ error: 'Whisper not configured. Set OPENAI_API_KEY.' });
-    var file = new File([req.file.buffer], 'audio.webm', { type: req.file.mimetype || 'audio/webm' });
+    var file   = new File([req.file.buffer], 'audio.webm', { type: req.file.mimetype || 'audio/webm' });
     var result = await whisperClient.audio.transcriptions.create({
       file, model: 'whisper-1', language: 'en',
       response_format: 'text',
@@ -105,8 +106,8 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
     var text = typeof result === 'string' ? result : result.text;
     console.log('[Transcribe] Whisper done in ' + (Date.now() - startTime) + 'ms');
     res.json({ success: true, text: text, provider: 'openai-whisper', duration: Date.now() - startTime });
+
   } catch (err) {
-    // Log full LiteLLM/upstream error body so we can diagnose
     var detail = err.response && err.response.data
       ? JSON.stringify(err.response.data).substring(0, 500)
       : err.message;

src/routes/tts.js

@@ -1,53 +1,62 @@
 const express = require('express');
-const router = express.Router();
+const router  = express.Router();
-const axios = require('axios');
+const axios   = require('axios');
+const { synthesizeWithGoogleTTS, isGoogleTTSConfigured } = require('../utils/ttsGoogle');
 const { authMiddleware } = require('../middleware/auth');
 
-// TTS_PROVIDER=litellm   → LiteLLM proxy (Vertex AI TTS, OpenAI TTS, etc.)
+// Provider priority (auto-detect):
+// TTS_PROVIDER=google     → Google Cloud TTS direct (HIPAA eligible)
+// TTS_PROVIDER=litellm    → LiteLLM proxy
 // TTS_PROVIDER=elevenlabs → ElevenLabs (not HIPAA)
-// (auto) LITELLM_API_BASE set → litellm
+// Auto: google > litellm > elevenlabs
-// (auto) ELEVENLABS_API_KEY set → elevenlabs
 function getTTSProvider() {
   var env = process.env.TTS_PROVIDER;
+  if (env === 'google')     return 'google';
   if (env === 'litellm')    return 'litellm';
   if (env === 'elevenlabs') return 'elevenlabs';
-  if (process.env.LITELLM_API_BASE) return 'litellm';
+  // Auto-detect: litellm > google > elevenlabs
+  // LiteLLM Vertex TTS works correctly via alias (tts-1)
+  if (process.env.LITELLM_API_BASE)   return 'litellm';
+  if (isGoogleTTSConfigured())        return 'google';
   if (process.env.ELEVENLABS_API_KEY) return 'elevenlabs';
   return 'none';
 }
 
 var ttsProvider = getTTSProvider();
-console.log('🔊 TTS provider:', ttsProvider);
+console.log('🔊 TTS provider:', ttsProvider +
+  (ttsProvider === 'google' ? ' (voice: ' + (process.env.GOOGLE_TTS_VOICE || 'en-US-Journey-F') + ')' : ''));
 
 router.post('/text-to-speech', authMiddleware, async (req, res) => {
   try {
     var text = (req.body.text || '').substring(0, 5000);
     if (!text) return res.status(400).json({ error: 'No text provided' });
 
+    if (ttsProvider === 'google') {
+      var buffer = await synthesizeWithGoogleTTS(text);
+      res.set('Content-Type', 'audio/mpeg');
+      return res.send(buffer);
+    }
+
     if (ttsProvider === 'litellm') {
       if (!process.env.LITELLM_API_BASE) return res.status(400).json({ error: 'LITELLM_API_BASE not set.' });
-      var ttsModel = process.env.LITELLM_TTS_MODEL || 'vertex_ai/text-to-speech';
+      // Model must be the model_name alias from LiteLLM model_list (e.g. tts-1, tts-1-hd)
-      var base = process.env.LITELLM_API_BASE.replace(/\/+$/, '');
+      // NOT the underlying vertex_ai/... path — LiteLLM routes by alias
+      var ttsModel   = process.env.LITELLM_TTS_MODEL || 'tts-1';
+      var ttsVoice   = process.env.LITELLM_TTS_VOICE || 'en-US-Journey-F';
+      var base       = process.env.LITELLM_API_BASE.replace(/\/+$/, '');
       var ttsHeaders = { 'Content-Type': 'application/json' };
       if (process.env.LITELLM_API_KEY) ttsHeaders['Authorization'] = 'Bearer ' + process.env.LITELLM_API_KEY;
-
+      var ttsResp = await axios.post(base + '/v1/audio/speech',
-      // Send only model + input — voice is configured inside LiteLLM per model
+        { model: ttsModel, voice: ttsVoice, input: text },
-      var ttsResp = await axios.post(base + '/v1/audio/speech', {
+        { headers: ttsHeaders, responseType: 'arraybuffer', timeout: 60000 }
-        model: ttsModel,
+      );
-        input: text
-      }, {
-        headers: ttsHeaders,
-        responseType: 'arraybuffer',
-        timeout: 60000
-      });
-
       res.set('Content-Type', 'audio/mpeg');
       return res.send(Buffer.from(ttsResp.data));
     }
 
     if (ttsProvider === 'elevenlabs') {
       if (!process.env.ELEVENLABS_API_KEY) return res.status(400).json({ error: 'ElevenLabs not configured' });
-      const response = await axios({
+      var resp = await axios({
         method: 'POST',
         url: 'https://api.elevenlabs.io/v1/text-to-speech/pNInz6obpgDQGcFmaJgB',
         headers: { 'xi-api-key': process.env.ELEVENLABS_API_KEY, 'Content-Type': 'application/json' },
@@ -55,10 +64,10 @@ router.post('/text-to-speech', authMiddleware, async (req, res) => {
         responseType: 'arraybuffer'
       });
       res.set('Content-Type', 'audio/mpeg');
-      return res.send(Buffer.from(response.data));
+      return res.send(Buffer.from(resp.data));
     }
 
-    res.status(400).json({ error: 'TTS not configured. Set LITELLM_API_BASE or ELEVENLABS_API_KEY.' });
+    res.status(400).json({ error: 'TTS not configured. Set GOOGLE_VERTEX_PROJECT, LITELLM_API_BASE, or ELEVENLABS_API_KEY.' });
   } catch (err) {
     var detail = err.response && err.response.data
       ? JSON.stringify(err.response.data).substring(0, 500)

src/utils/transcribeGoogle.js

@@ -0,0 +1,45 @@
+// ============================================================
+// TRANSCRIBE GOOGLE — Vertex AI / Gemini audio transcription
+// Sends audio inline to Gemini which returns spoken text.
+// Supports: gemini-2.0-flash (default), gemini-2.5-flash
+// Requires: GOOGLE_VERTEX_PROJECT, @google-cloud/vertexai installed
+// ============================================================
+
+async function transcribeWithGemini(buffer, mimeType) {
+  var VertexModule = require('@google-cloud/vertexai');
+  var project  = process.env.GOOGLE_VERTEX_PROJECT;
+  var location = process.env.GOOGLE_VERTEX_LOCATION || 'us-central1';
+  if (!project) throw new Error('GOOGLE_VERTEX_PROJECT not set');
+
+  var vertex = new VertexModule.VertexAI({ project: project, location: location });
+  var model  = vertex.getGenerativeModel({
+    model: process.env.GOOGLE_STT_MODEL || 'gemini-2.0-flash'
+  });
+
+  var base64   = buffer.toString('base64');
+  var safeMime = mimeType || 'audio/webm';
+
+  var result = await model.generateContent({
+    contents: [{
+      role: 'user',
+      parts: [
+        { inlineData: { mimeType: safeMime, data: base64 } },
+        { text: 'Transcribe this audio. Output the spoken words only, exactly as heard. No commentary, no formatting, no explanation.' }
+      ]
+    }]
+  });
+
+  var text = '';
+  if (result.response && result.response.candidates && result.response.candidates[0]) {
+    var parts = result.response.candidates[0].content.parts || [];
+    parts.forEach(function(p) { if (p.text) text += p.text; });
+  }
+  return text.trim();
+}
+
+function isGoogleSTTConfigured() {
+  if (!process.env.GOOGLE_VERTEX_PROJECT) return false;
+  try { require('@google-cloud/vertexai'); return true; } catch(e) { return false; }
+}
+
+module.exports = { transcribeWithGemini, isGoogleSTTConfigured };

src/utils/ttsGoogle.js

@@ -0,0 +1,47 @@
+// ============================================================
+// TTS GOOGLE — Google Cloud Text-to-Speech (direct, no LiteLLM)
+// Uses google-auth-library (transitive dep of @google-cloud/vertexai)
+// Voices: en-US-Journey-F (female), en-US-Journey-D (male),
+//         en-US-Studio-O, en-US-Neural2-C, etc.
+// Requires: GOOGLE_VERTEX_PROJECT, ADC or GOOGLE_APPLICATION_CREDENTIALS
+// ============================================================
+
+async function synthesizeWithGoogleTTS(text) {
+  var GoogleAuth = require('google-auth-library').GoogleAuth;
+  var axios = require('axios');
+
+  var auth = new GoogleAuth({
+    scopes: ['https://www.googleapis.com/auth/cloud-platform']
+  });
+
+  var client    = await auth.getClient();
+  var tokenData = await client.getAccessToken();
+  var token     = tokenData.token;
+  var voice     = process.env.GOOGLE_TTS_VOICE || 'en-US-Journey-F';
+  var langCode  = voice.substring(0, 5); // e.g. en-US
+
+  var resp = await axios.post(
+    'https://texttospeech.googleapis.com/v1/text:synthesize',
+    {
+      input: { text: text },
+      voice: { languageCode: langCode, name: voice },
+      audioConfig: { audioEncoding: 'MP3' }
+    },
+    {
+      headers: {
+        'Authorization': 'Bearer ' + token,
+        'Content-Type': 'application/json'
+      },
+      timeout: 30000
+    }
+  );
+
+  return Buffer.from(resp.data.audioContent, 'base64');
+}
+
+function isGoogleTTSConfigured() {
+  if (!process.env.GOOGLE_VERTEX_PROJECT) return false;
+  try { require('google-auth-library'); return true; } catch(e) { return false; }
+}
+
+module.exports = { synthesizeWithGoogleTTS, isGoogleTTSConfigured };