fix: 增强错误日志，修复API调用诊断

services/llm_service.py

@@ -232,7 +232,7 @@ class LLMService:
         temperature: float = 0.7
     ) -> str:
         """调用API"""
-        url = f"{api_base}/chat/completions"
+        url = f"{api_base.rstrip('/')}/chat/completions"
         headers = {
             "Authorization": f"Bearer {api_key}",
             "Content-Type": "application/json"
@@ -244,13 +244,33 @@ class LLMService:
             "max_tokens": max_tokens
         }
         
+        # 打印请求详情（调试）
         logger.info(f"调用LLM: url={url}, model={model}")
+        logger.info(f"消息数量: {len(messages)}, 第一条消息类型: {type(messages[0].get('content'))}")
         
-        async with httpx.AsyncClient(timeout=60.0) as client:
-            response = await client.post(url, headers=headers, json=payload)
-            response.raise_for_status()
-            data = response.json()
-            return data['choices'][0]['message']['content']
+        try:
+            async with httpx.AsyncClient(timeout=60.0) as client:
+                response = await client.post(url, headers=headers, json=payload)
+                
+                # 检查HTTP状态
+                if response.status_code != 200:
+                    logger.error(f"API返回错误: status={response.status_code}, body={response.text[:500]}")
+                    response.raise_for_status()
+                
+                data = response.json()
+                
+                # 检查响应格式
+                if 'choices' not in data or len(data['choices']) == 0:
+                    logger.error(f"API响应格式错误: {data}")
+                    raise ValueError("API响应格式错误：缺少choices")
+                
+                return data['choices'][0]['message']['content']
+        except httpx.HTTPStatusError as e:
+            logger.error(f"HTTP错误: {e.response.status_code}, {e.response.text}")
+            raise
+        except Exception as e:
+            logger.error(f"API调用异常: {type(e).__name__}: {e}")
+            raise
     
     async def chat_stream(
         self,