feat: add provider compatibility error detection for intelligent failover

- Introduce ProviderCompatibilityException for unsupported parameter/feature errors
- Add COMPATIBILITY_ERROR_PATTERNS to detect provider-specific limitations
- Implement _is_compatibility_error() method in ErrorClassifier
- Prioritize compatibility error checking before client error validation
- Remove 'max_tokens' from CLIENT_ERROR_PATTERNS as it can indicate compatibility issues
- Enable automatic failover when provider doesn't support requested features
- Improve error classification accuracy with pattern matching for common compatibility issues

src/core/exceptions.py

@@ -442,6 +442,36 @@ class EmbeddedErrorException(ProviderException):
         self.error_status = error_status
 
 
+class ProviderCompatibilityException(ProviderException):
+    """Provider 兼容性错误异常 - 应该触发故障转移
+
+    用于处理因 Provider 不支持某些参数或功能导致的错误。
+    这类错误不是用户请求本身的问题，换一个 Provider 可能就能成功，应该触发故障转移。
+
+    常见场景：
+    - Unsupported parameter（不支持的参数）
+    - Unsupported model（不支持的模型）
+    - Unsupported feature（不支持的功能）
+    """
+
+    def __init__(
+        self,
+        message: str,
+        provider_name: Optional[str] = None,
+        status_code: int = 400,
+        upstream_error: Optional[str] = None,
+        request_metadata: Optional[Any] = None,
+    ):
+        self.upstream_error = upstream_error
+        super().__init__(
+            message=message,
+            provider_name=provider_name,
+            request_metadata=request_metadata,
+        )
+        # 覆盖状态码为 400（保持与上游一致）
+        self.status_code = status_code
+
+
 class UpstreamClientException(ProxyException):
     """上游返回的客户端错误异常 - HTTP 4xx 错误，不应该重试
 

src/services/orchestration/error_classifier.py

@@ -15,6 +15,7 @@ from src.core.enums import APIFormat
 from src.core.exceptions import (
     ConcurrencyLimitError,
     ProviderAuthException,
+    ProviderCompatibilityException,
     ProviderException,
     ProviderNotAvailableException,
     ProviderRateLimitException,
@@ -81,7 +82,9 @@ class ErrorClassifier:
         "context_length_exceeded",  # 上下文长度超限
         "content_length_limit",  # 请求内容长度超限 (Claude API)
         "content_length_exceeds",  # 内容长度超限变体 (AWS CodeWhisperer)
-        "max_tokens",  # token 数超限
+        # 注意：移除了 "max_tokens"，因为 max_tokens 相关错误可能是 Provider 兼容性问题
+        # 如 "Unsupported parameter: 'max_tokens' is not supported with this model"
+        # 这类错误应由 COMPATIBILITY_ERROR_PATTERNS 处理
         "invalid_prompt",  # 无效的提示词
         "content too long",  # 内容过长
         "input is too long",  # 输入过长 (AWS)
@@ -136,6 +139,19 @@ class ErrorClassifier:
         "CONTENT_POLICY_VIOLATION",
     )
 
+    # Provider 兼容性错误模式 - 这类错误应该触发故障转移
+    # 因为换一个 Provider 可能就能成功
+    COMPATIBILITY_ERROR_PATTERNS: Tuple[str, ...] = (
+        "unsupported parameter",  # 不支持的参数
+        "unsupported model",  # 不支持的模型
+        "unsupported feature",  # 不支持的功能
+        "not supported with this model",  # 此模型不支持
+        "model does not support",  # 模型不支持
+        "parameter is not supported",  # 参数不支持
+        "feature is not supported",  # 功能不支持
+        "not available for this model",  # 此模型不可用
+    )
+
     def _parse_error_response(self, error_text: Optional[str]) -> Dict[str, Any]:
         """
         解析错误响应为结构化数据
@@ -261,6 +277,25 @@ class ErrorClassifier:
         search_text = f"{parsed['message']} {parsed['raw']}".lower()
         return any(pattern.lower() in search_text for pattern in self.CLIENT_ERROR_PATTERNS)
 
+    def _is_compatibility_error(self, error_text: Optional[str]) -> bool:
+        """
+        检测错误响应是否为 Provider 兼容性错误（应触发故障转移）
+
+        这类错误是因为 Provider 不支持某些参数或功能导致的，
+        换一个 Provider 可能就能成功。
+
+        Args:
+            error_text: 错误响应文本
+
+        Returns:
+            是否为兼容性错误
+        """
+        if not error_text:
+            return False
+
+        search_text = error_text.lower()
+        return any(pattern.lower() in search_text for pattern in self.COMPATIBILITY_ERROR_PATTERNS)
+
     def _extract_error_message(self, error_text: Optional[str]) -> Optional[str]:
         """
         从错误响应中提取错误消息
@@ -425,6 +460,16 @@ class ErrorClassifier:
                 ),
             )
 
+        # 400 错误：先检查是否为 Provider 兼容性错误（应触发故障转移）
+        if status == 400 and self._is_compatibility_error(error_response_text):
+            logger.info(f"检测到 Provider 兼容性错误，将触发故障转移: {extracted_message}")
+            return ProviderCompatibilityException(
+                message=extracted_message or "Provider 不支持此请求",
+                provider_name=provider_name,
+                status_code=400,
+                upstream_error=error_response_text,
+            )
+
         # 400 错误：检查是否为客户端请求错误（不应重试）
         if status == 400 and self._is_client_error(error_response_text):
             logger.info(f"检测到客户端请求错误，不进行重试: {extracted_message}")