fix(anthropic): improve MCP tool message handling and error resilience

修复Anthropic协议中MCP工具消息处理问题，增强错误恢复能力：
- 改进MessageContent的JSON解析，支持原始JSON数据保留
- 移除对空内容的过滤，避免丢失MCP工具消息
- 增加详细调试日志，便于问题排查
- 优化错误响应处理，保留响应体信息
- 修复路由转发时可能的数据丢失问题

fix(anthropic): improve MCP tool message handling and error resilience
- Enhance MessageContent JSON parsing to preserve raw JSON data
- Remove empty content filtering to prevent MCP tool message loss
- Add detailed debug logging for troubleshooting
- Optimize error response handling with response body preservation
- Fix potential data loss during routing

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

relay/adaptor/anthropic/main.go

@@ -107,10 +107,12 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *Request {
 		claudeMessage := Message{
 			Role: message.Role,
 		}
-		var content Content
+		var contents []Content
 		if message.IsStringContent() {
-			content.Type = "text"
-			content.Text = message.StringContent()
+			content := Content{
+				Type: "text",
+				Text: message.StringContent(),
+			}
 			if message.Role == "tool" {
 				claudeMessage.Role = "user"
 				content.Type = "tool_result"
@@ -118,21 +120,22 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *Request {
 				content.Text = ""
 				content.ToolUseId = message.ToolCallId
 			}
-			claudeMessage.Content = append(claudeMessage.Content, content)
+			contents = append(contents, content)
 			for i := range message.ToolCalls {
 				inputParam := make(map[string]any)
 				_ = json.Unmarshal([]byte(message.ToolCalls[i].Function.Arguments.(string)), &inputParam)
-				claudeMessage.Content = append(claudeMessage.Content, Content{
+				contents = append(contents, Content{
 					Type:  "tool_use",
 					Id:    message.ToolCalls[i].Id,
 					Name:  message.ToolCalls[i].Function.Name,
 					Input: inputParam,
 				})
 			}
+			claudeMessage.Content = MessageContent{value: contents}
 			claudeRequest.Messages = append(claudeRequest.Messages, claudeMessage)
 			continue
 		}
-		var contents []Content
+		contents = []Content{} // Reset the slice for reuse
 		openaiContent := message.ParseContent()
 		for _, part := range openaiContent {
 			var content Content
@@ -150,7 +153,7 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *Request {
 			}
 			contents = append(contents, content)
 		}
-		claudeMessage.Content = contents
+		claudeMessage.Content = MessageContent{value: contents}
 		claudeRequest.Messages = append(claudeRequest.Messages, claudeMessage)
 	}
 	return &claudeRequest
@@ -220,11 +223,12 @@ func StreamResponseClaude2OpenAI(claudeResponse *StreamResponse) (*openai.ChatCo
 
 func ResponseClaude2OpenAI(claudeResponse *Response) *openai.TextResponse {
 	var responseText string
-	if len(claudeResponse.Content) > 0 {
-		responseText = claudeResponse.Content[0].Text
+	contentArray := claudeResponse.Content.ToContentArray()
+	if len(contentArray) > 0 {
+		responseText = contentArray[0].Text
 	}
 	tools := make([]model.Tool, 0)
-	for _, v := range claudeResponse.Content {
+	for _, v := range contentArray {
 		if v.Type == "tool_use" {
 			args, _ := json.Marshal(v.Input)
 			tools = append(tools, model.Tool{

relay/adaptor/anthropic/model.go

@@ -29,9 +29,80 @@ type Content struct {
 	ToolUseId string `json:"tool_use_id,omitempty"`
 }
 
+// MessageContent can handle both string and array formats for the content field
+type MessageContent struct {
+	value interface{}
+}
+
+// UnmarshalJSON implements json.Unmarshaler to handle both string and array formats
+func (m *MessageContent) UnmarshalJSON(data []byte) error {
+	// Skip empty data or null
+	if len(data) == 0 || string(data) == "null" {
+		m.value = ""
+		return nil
+	}
+
+	// Try to unmarshal as string first
+	var str string
+	if err := json.Unmarshal(data, &str); err == nil {
+		m.value = str
+		return nil
+	}
+
+	// If that fails, try to unmarshal as array of Content
+	var arr []Content
+	if err := json.Unmarshal(data, &arr); err == nil {
+		m.value = arr
+		return nil
+	}
+
+	// For routing purposes, store raw JSON if we can't parse it
+	// This ensures we don't lose any data during forwarding
+	var raw json.RawMessage
+	if err := json.Unmarshal(data, &raw); err == nil {
+		m.value = raw
+		return nil
+	}
+
+	return fmt.Errorf("message content must be either a string or an array of content blocks")
+}
+
+// MarshalJSON implements json.Marshaler
+func (m MessageContent) MarshalJSON() ([]byte, error) {
+	return json.Marshal(m.value)
+}
+
+// ToContentArray converts the message content to a []Content array
+func (m MessageContent) ToContentArray() []Content {
+	if m.value == nil {
+		return []Content{}
+	}
+
+	switch v := m.value.(type) {
+	case string:
+		// Convert string to a single text content block
+		return []Content{{
+			Type: "text",
+			Text: v,
+		}}
+	case []Content:
+		return v
+	case json.RawMessage:
+		// Try to parse raw JSON as Content array
+		var arr []Content
+		if err := json.Unmarshal(v, &arr); err == nil {
+			return arr
+		}
+		// If that fails, return empty array to avoid breaking the routing
+		return []Content{}
+	default:
+		return []Content{}
+	}
+}
+
 type Message struct {
-	Role    string    `json:"role"`
-	Content []Content `json:"content"`
+	Role    string         `json:"role"`
+	Content MessageContent `json:"content"`
 }
 
 type Tool struct {
@@ -146,15 +217,15 @@ type Error struct {
 }
 
 type Response struct {
-	Id           string    `json:"id"`
-	Type         string    `json:"type"`
-	Role         string    `json:"role"`
-	Content      []Content `json:"content"`
-	Model        string    `json:"model"`
-	StopReason   *string   `json:"stop_reason"`
-	StopSequence *string   `json:"stop_sequence"`
-	Usage        Usage     `json:"usage"`
-	Error        Error     `json:"error"`
+	Id           string         `json:"id"`
+	Type         string         `json:"type"`
+	Role         string         `json:"role"`
+	Content      MessageContent `json:"content"`
+	Model        string         `json:"model"`
+	StopReason   *string        `json:"stop_reason"`
+	StopSequence *string        `json:"stop_sequence"`
+	Usage        Usage          `json:"usage"`
+	Error        Error          `json:"error"`
 }
 
 type Delta struct {

relay/controller/anthropic.go

@@ -87,7 +87,18 @@ func RelayAnthropicHelper(c *gin.Context) *model.ErrorWithStatusCode {
 	logger.Debugf(ctx, "Received response - Status: %d", resp.StatusCode)
 
 	if isErrorHappened(meta, resp) {
-		logger.Errorf(ctx, "Error detected in response")
+		logger.Errorf(ctx, "Error detected in response - Status: %d", resp.StatusCode)
+
+		// Read response body for detailed error logging
+		if resp.Body != nil {
+			bodyBytes, readErr := io.ReadAll(resp.Body)
+			if readErr == nil {
+				logger.Errorf(ctx, "Error response body: %s", string(bodyBytes))
+				// Recreate the body for further processing
+				resp.Body = io.NopCloser(bytes.NewReader(bodyBytes))
+			}
+		}
+
 		billing.ReturnPreConsumedQuota(ctx, preConsumedQuota, meta.TokenId)
 		return RelayErrorHandler(resp)
 	}
@@ -111,13 +122,17 @@ func RelayAnthropicHelper(c *gin.Context) *model.ErrorWithStatusCode {
 }
 
 func getAndValidateAnthropicRequest(c *gin.Context) (*anthropic.Request, error) {
+	ctx := c.Request.Context()
 	anthropicRequest := &anthropic.Request{}
 	err := common.UnmarshalBodyReusable(c, anthropicRequest)
 	if err != nil {
+		logger.Errorf(ctx, "Failed to unmarshal Anthropic request: %s", err.Error())
 		return nil, err
 	}
 
-	// Basic validation
+	logger.Debugf(ctx, "Successfully parsed Anthropic request with %d messages", len(anthropicRequest.Messages))
+
+	// Basic validation only - minimal intervention
 	if anthropicRequest.Model == "" {
 		return nil, fmt.Errorf("model is required")
 	}
@@ -128,6 +143,26 @@ func getAndValidateAnthropicRequest(c *gin.Context) (*anthropic.Request, error)
 		anthropicRequest.MaxTokens = 4096 // default max tokens
 	}
 
+	// Add detailed logging for debugging without filtering messages
+	logger.Debugf(ctx, "Request details - Model: %s, MaxTokens: %d, Messages: %d",
+		anthropicRequest.Model, anthropicRequest.MaxTokens, len(anthropicRequest.Messages))
+
+	for i, message := range anthropicRequest.Messages {
+		contentArray := message.Content.ToContentArray()
+		logger.Debugf(ctx, "Message[%d] - Role: %s, Content blocks: %d", i, message.Role, len(contentArray))
+
+		for j, content := range contentArray {
+			if content.Type == "tool_use" {
+				logger.Debugf(ctx, "  Content[%d] - Type: %s, ID: %s, Name: %s", j, content.Type, content.Id, content.Name)
+			} else if content.Type == "tool_result" {
+				logger.Debugf(ctx, "  Content[%d] - Type: %s, ToolUseId: %s, Content length: %d",
+					j, content.Type, content.ToolUseId, len(content.Content))
+			} else {
+				logger.Debugf(ctx, "  Content[%d] - Type: %s, Text length: %d", j, content.Type, len(content.Text))
+			}
+		}
+	}
+
 	return anthropicRequest, nil
 }
 
@@ -135,10 +170,14 @@ func getAnthropicRequestBody(c *gin.Context, anthropicRequest *anthropic.Request
 	// For anthropic native requests, we marshal the request back to JSON
 	jsonData, err := json.Marshal(anthropicRequest)
 	if err != nil {
-		logger.Debugf(c.Request.Context(), "anthropic request json_marshal_failed: %s\n", err.Error())
+		logger.Errorf(c.Request.Context(), "Failed to marshal anthropic request: %s", err.Error())
 		return nil, err
 	}
-	logger.Debugf(c.Request.Context(), "anthropic request: \n%s", string(jsonData))
+
+	ctx := c.Request.Context()
+	logger.Debugf(ctx, "Final request body size: %d bytes", len(jsonData))
+	logger.Debugf(ctx, "Final request body: %s", string(jsonData))
+
 	return bytes.NewBuffer(jsonData), nil
 }
 
@@ -161,7 +200,7 @@ func estimateAnthropicTokens(request *anthropic.Request) int {
 
 	// Count tokens in messages
 	for _, message := range request.Messages {
-		for _, content := range message.Content {
+		for _, content := range message.Content.ToContentArray() {
 			if content.Type == "text" {
 				totalTokens += len(content.Text) / CHARS_PER_TOKEN
 			}