添加对gemini原生格式TTS的支持

app/service/chat/gemini_chat_service.py

@@ -140,14 +140,29 @@ def _build_payload(model: str, request: GeminiRequest) -> Dict[str, Any]:
         if request.generationConfig.maxOutputTokens is None:
             # 如果未指定最大输出长度，则不传递该字段，解决截断的问题
             request_dict["generationConfig"].pop("maxOutputTokens")
-    
-    payload = {
-        "contents": _filter_empty_parts(request_dict.get("contents", [])),
-        "tools": _build_tools(model, request_dict),
-        "safetySettings": _get_safety_settings(model),
-        "generationConfig": request_dict.get("generationConfig"),
-        "systemInstruction": request_dict.get("systemInstruction"),
-    }
+
+    # 检查是否为TTS模型
+    is_tts_model = "tts" in model.lower()
+
+    if is_tts_model:
+        # TTS模型使用简化的payload，不包含tools和safetySettings
+        payload = {
+            "contents": _filter_empty_parts(request_dict.get("contents", [])),
+            "generationConfig": request_dict.get("generationConfig"),
+        }
+
+        # 只在有systemInstruction时才添加
+        if request_dict.get("systemInstruction"):
+            payload["systemInstruction"] = request_dict.get("systemInstruction")
+    else:
+        # 非TTS模型使用完整的payload
+        payload = {
+            "contents": _filter_empty_parts(request_dict.get("contents", [])),
+            "tools": _build_tools(model, request_dict),
+            "safetySettings": _get_safety_settings(model),
+            "generationConfig": request_dict.get("generationConfig"),
+            "systemInstruction": request_dict.get("systemInstruction"),
+        }
 
     # 确保 generationConfig 不为 None
     if payload["generationConfig"] is None: