chore: add system instruction to enhance compliance with function call

app/services/openai_chat_service.py

@@ -2,7 +2,7 @@
 
 from copy import deepcopy
 import json
-from typing import Dict, Any, AsyncGenerator, List, Union
+from typing import Dict, Any, AsyncGenerator, List, Optional, Union
 from app.core.logger import get_openai_logger
 from app.services.chat.message_converter import OpenAIMessageConverter
 from app.services.chat.response_handler import OpenAIResponseHandler
@@ -87,10 +87,10 @@ def _get_safety_settings(model: str) -> List[Dict[str, str]]:
 
 
 def _build_payload(
-        request: ChatRequest, messages: List[Dict[str, Any]]
+    request: ChatRequest, messages: List[Dict[str, Any]], instruction: Optional[Dict[str, Any]] = None
 ) -> Dict[str, Any]:
     """构建请求payload"""
-    return {
+    payload = {
         "contents": messages,
         "generationConfig": {
             "temperature": request.temperature,
@@ -103,6 +103,16 @@ def _build_payload(
         "safetySettings": _get_safety_settings(request.model),
     }
 
+    if (
+        instruction
+        and isinstance(instruction, dict)
+        and instruction.get("role") == "system"
+        and instruction.get("parts")
+    ):
+        payload["systemInstruction"] = instruction
+
+    return payload
+
 
 class OpenAIChatService:
     """聊天服务"""
@@ -120,10 +130,10 @@ class OpenAIChatService:
     ) -> Union[Dict[str, Any], AsyncGenerator[str, None]]:
         """创建聊天完成"""
         # 转换消息格式
-        messages = self.message_converter.convert(request.messages)
+        messages, instruction = self.message_converter.convert(request.messages)
 
         # 构建请求payload
-        payload = _build_payload(request, messages)
+        payload = _build_payload(request, messages, instruction)
 
         if request.stream:
             return self._handle_stream_completion(request.model, payload, api_key)