refactor: 统一响应解析中的嵌套错误检测逻辑

- 提取 _check_nested_error 函数处理多种错误格式
- 支持检测顶层 error、type=error 以及 chunks 内嵌套的错误
- 简化 OpenAIResponseParser 和 ClaudeResponseParser 中的错误处理代码
- 提高代码复用性和可维护性

src/api/handlers/base/parsers.py

@@ -5,7 +5,7 @@
 不再经过 Protocol 抽象层。
 """
 
-from typing import Any, Dict, Optional
+from typing import Any, Dict, Optional, Tuple
 
 from src.api.handlers.base.response_parser import (
     ParsedChunk,
@@ -15,6 +15,48 @@ from src.api.handlers.base.response_parser import (
 )
 
 
+def _check_nested_error(response: Dict[str, Any]) -> Tuple[bool, Optional[Dict[str, Any]]]:
+    """
+    检查响应中是否存在嵌套错误（某些代理服务返回 HTTP 200 但在响应体中包含错误）
+
+    检测格式:
+    1. 顶层 error: {"error": {...}}
+    2. 顶层 type=error: {"type": "error", ...}
+    3. chunks 内嵌套 error: {"chunks": [{"error": {...}}]}
+
+    Args:
+        response: 响应字典
+
+    Returns:
+        (is_error, error_dict): 是否为错误，以及提取的错误信息
+    """
+    # 顶层 error
+    if "error" in response:
+        error = response["error"]
+        if isinstance(error, dict):
+            return True, error
+        return True, {"message": str(error)}
+
+    # 顶层 type=error
+    if response.get("type") == "error":
+        return True, response
+
+    # chunks 内嵌套 error (某些代理返回这种格式)
+    chunks = response.get("chunks", [])
+    if chunks and isinstance(chunks, list):
+        for chunk in chunks:
+            if isinstance(chunk, dict):
+                if "error" in chunk:
+                    error = chunk["error"]
+                    if isinstance(error, dict):
+                        return True, error
+                    return True, {"message": str(error)}
+                if chunk.get("type") == "error":
+                    return True, chunk
+
+    return False, None
+
+
 class OpenAIResponseParser(ResponseParser):
     """OpenAI 格式响应解析器"""
 
@@ -81,15 +123,12 @@ class OpenAIResponseParser(ResponseParser):
         result.input_tokens = usage.get("prompt_tokens", 0)
         result.output_tokens = usage.get("completion_tokens", 0)
 
-        # 检查错误
-        if "error" in response:
+        # 检查错误（支持嵌套错误格式）
+        is_error, error_info = _check_nested_error(response)
+        if is_error and error_info:
             result.is_error = True
-            error = response.get("error", {})
-            if isinstance(error, dict):
-                result.error_type = error.get("type")
-                result.error_message = error.get("message")
-            else:
-                result.error_message = str(error)
+            result.error_type = error_info.get("type")
+            result.error_message = error_info.get("message")
 
         return result
 
@@ -112,7 +151,8 @@ class OpenAIResponseParser(ResponseParser):
         return ""
 
     def is_error_response(self, response: Dict[str, Any]) -> bool:
-        return "error" in response
+        is_error, _ = _check_nested_error(response)
+        return is_error
 
 
 class OpenAICliResponseParser(OpenAIResponseParser):
@@ -215,15 +255,12 @@ class ClaudeResponseParser(ResponseParser):
         result.cache_creation_tokens = usage.get("cache_creation_input_tokens", 0)
         result.cache_read_tokens = usage.get("cache_read_input_tokens", 0)
 
-        # 检查错误
-        if "error" in response or response.get("type") == "error":
+        # 检查错误（支持嵌套错误格式）
+        is_error, error_info = _check_nested_error(response)
+        if is_error and error_info:
             result.is_error = True
-            error = response.get("error", {})
-            if isinstance(error, dict):
-                result.error_type = error.get("type")
-                result.error_message = error.get("message")
-            else:
-                result.error_message = str(error)
+            result.error_type = error_info.get("type")
+            result.error_message = error_info.get("message")
 
         return result
 
@@ -247,7 +284,8 @@ class ClaudeResponseParser(ResponseParser):
         return ""
 
     def is_error_response(self, response: Dict[str, Any]) -> bool:
-        return "error" in response or response.get("type") == "error"
+        is_error, _ = _check_nested_error(response)
+        return is_error
 
 
 class ClaudeCliResponseParser(ClaudeResponseParser):