logic fix: TTS

services/geminiService.ts

@@ -29,10 +29,10 @@ const ai = new GoogleGenAI({ apiKey: API_KEY });
 
 // --- TIERED MODEL STRATEGY ---
 // 1. Primary: Gemini 2.5 Flash (Highest Quality/Speed Balance)
-// 2. Secondary: Gemini 2.5 Flash-Lite (Quota Rescue)
+// 2. Secondary: Gemini Flash Lite (Quota Rescue)
 // 3. Tertiary: Local/HuggingFace Backends (Privacy/Offline/No-Quota Fallback)
 const MODEL_PRIMARY = 'gemini-2.5-flash'; 
-const MODEL_SECONDARY = 'gemini-2.5-flash-lite'; 
+const MODEL_SECONDARY = 'gemini-flash-lite-latest'; 
 const MODEL_TTS = 'gemini-2.5-flash-preview-tts';
 
 // --- UTILITIES ---
@@ -108,7 +108,7 @@ const callBackend = async (baseUrl: string, endpoint: string, payload: any, onSt
       if (typeof data === 'string') return data;
       if (data.text) return data.text;
       if (data.response) return data.response;
-      if (data.audio) return data.audio; // For TTS
+      // Note: Backend does not support TTS, so we don't check for audio here.
       
       return JSON.stringify(data);
 
@@ -142,14 +142,13 @@ async function executePipeline<T>(
         if (onStatus) onStatus("⚡ Using Gemini Flash...");
         return await geminiTask(MODEL_PRIMARY);
     } catch (error: any) {
-        // Check for Quota/Rate Limits
-        if (error.toString().includes('429') || error.toString().includes('Quota') || error.toString().includes('Resource has been exhausted')) {
+        // Check for Quota/Rate Limits or Model Overload
+        if (error.toString().includes('429') || error.toString().includes('Quota') || error.toString().includes('503')) {
             try {
                 // 2. Secondary Model
                 if (onStatus) onStatus("⚠️ Quota limit. Switching to Flash-Lite...");
                 return await geminiTask(MODEL_SECONDARY);
             } catch (secondaryError) {
-                // Fall through to backend
                 console.warn("Secondary model failed:", secondaryError);
             }
         }
@@ -210,13 +209,22 @@ export const generateSpeech = async (text: string): Promise<string | null> => {
     return response.candidates?.[0]?.content?.parts?.[0]?.inlineData?.data || null;
   };
 
-  // Fallback (somAI-media / TTS endpoint)
-  // Note: Backend must support /tts. If missing, this will fail gracefully.
+  // Fallback: Return NULL. 
+  // The Frontend (Chat.tsx) will detect NULL and use `window.speechSynthesis` (Browser Native TTS).
+  // The backend does not have a /tts endpoint.
   const fallbackTask = async () => {
-    return await callBackend(MEDIA_BACKEND_BASE, '/tts', { text });
+    return null; 
   };
 
-  return executePipeline(geminiTask, fallbackTask);
+  // We manually handle pipeline here to ensure fallback returns null instead of throwing
+  if (API_KEY) {
+      try {
+          return await geminiTask();
+      } catch (e) {
+          // Fallthrough
+      }
+  }
+  return await fallbackTask();
 };
 
 // --- STT (Transcription) ---
@@ -287,7 +295,7 @@ export const analyzeRisk = async (
     });
     
     const parsed = parseRiskResponse(response.text || "{}", calculatedScore);
-    return { ...parsed, source: model === MODEL_PRIMARY ? 'Gemini 2.5 Flash' : 'Gemini 2.5 Flash-Lite' };
+    return { ...parsed, source: model === MODEL_PRIMARY ? 'Gemini 2.5 Flash' : 'Gemini Flash Lite' };
   };
 
   const fallbackTask = async () => {
@@ -321,7 +329,7 @@ export const generateChatResponse = async (
   contents.push({ role: 'user', parts: [{ text: context + "\nUser: " + currentMessage }, ...(image ? [{ inlineData: { mimeType: 'image/jpeg', data: image.split('base64,')[1] } }] : [])] });
 
   const geminiTask = async (model: string) => {
-    onSource(model === MODEL_PRIMARY ? 'Gemini 2.5 Flash' : 'Gemini 2.5 Flash-Lite'); 
+    onSource(model === MODEL_PRIMARY ? 'Gemini 2.5 Flash' : 'Gemini Flash Lite'); 
     const response = await ai.models.generateContent({
         model: model,
         contents: contents,
@@ -344,7 +352,7 @@ export const generateChatResponse = async (
 const parseRiskResponse = (text: string, calculatedScore: number): RiskAnalysisResult => {
     try {
       let jsonStr = text;
-      // Clean markdown code blocks
+      // Clean markdown code blocks if any
       jsonStr = jsonStr.replace(/```json/g, '').replace(/```/g, '');
       const data = JSON.parse(jsonStr);