feat: improve OpenAI messages compatibility for Claude Code

backend/internal/service/openai_gateway_service.go

@@ -211,9 +211,10 @@ type OpenAIUsage struct {
 
 // OpenAIForwardResult represents the result of forwarding
 type OpenAIForwardResult struct {
-	RequestID string
-	Usage     OpenAIUsage
-	Model     string // 原始模型（用于响应和日志显示）
+	RequestID  string
+	ResponseID string
+	Usage      OpenAIUsage
+	Model      string // 原始模型（用于响应和日志显示）
 	// BillingModel is the model used for cost calculation.
 	// When non-empty, CalculateCost uses this instead of Model.
 	// This is set by the Anthropic Messages conversion path where
@@ -346,10 +347,12 @@ type OpenAIGatewayService struct {
 	openaiWSPassthroughDialer     openAIWSClientDialer
 	openaiAccountStats            *openAIAccountRuntimeStats
 
-	openaiWSFallbackUntil sync.Map // key: int64(accountID), value: time.Time
-	openaiWSRetryMetrics  openAIWSRetryMetrics
-	responseHeaderFilter  *responseheaders.CompiledHeaderFilter
-	codexSnapshotThrottle *accountWriteThrottle
+	openaiWSFallbackUntil               sync.Map // key: int64(accountID), value: time.Time
+	openaiWSRetryMetrics                openAIWSRetryMetrics
+	responseHeaderFilter                *responseheaders.CompiledHeaderFilter
+	codexSnapshotThrottle               *accountWriteThrottle
+	openaiCompatSessionResponses        sync.Map
+	openaiCompatAnthropicDigestSessions sync.Map
 }
 
 // NewOpenAIGatewayService creates a new OpenAIGatewayService
@@ -1992,6 +1995,8 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 	originalBody := body
 	reqModel, reqStream, promptCacheKey := extractOpenAIRequestMetaFromBody(body)
 	originalModel := reqModel
+	compatMessagesBridge := isOpenAICompatMessagesBridgeBody(body)
+	setOpenAICompatMessagesBridgeContext(c, compatMessagesBridge)
 
 	isCodexCLI := openai.IsCodexOfficialClientByHeaders(c.GetHeader("User-Agent"), c.GetHeader("originator")) || (s.cfg != nil && s.cfg.Gateway.ForceCodexCLI)
 	wsDecision := s.getOpenAIWSProtocolResolver().Resolve(account)
@@ -2117,7 +2122,7 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 	}
 
 	// 非透传模式下，instructions 为空时注入默认指令。
-	if isInstructionsEmpty(reqBody) {
+	if isInstructionsEmpty(reqBody) && !compatMessagesBridge {
 		reqBody["instructions"] = "You are a helpful coding assistant."
 		bodyModified = true
 		markPatchSet("instructions", "You are a helpful coding assistant.")
@@ -2246,7 +2251,20 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 	}
 
 	if account.Type == AccountTypeOAuth {
-		codexResult := applyCodexOAuthTransform(reqBody, isCodexCLI, isCompactRequest)
+		codexResult := codexTransformResult{}
+		if compatMessagesBridge {
+			codexResult = applyCodexOAuthTransformWithOptions(reqBody, codexOAuthTransformOptions{
+				IsCodexCLI:              isCodexCLI,
+				IsCompact:               isCompactRequest,
+				SkipDefaultInstructions: true,
+				PreserveToolCallIDs:     true,
+			})
+			ensureCodexOAuthInstructionsField(reqBody)
+			bodyModified = true
+			disablePatch()
+		} else {
+			codexResult = applyCodexOAuthTransform(reqBody, isCodexCLI, isCompactRequest)
+		}
 		if codexResult.Modified {
 			bodyModified = true
 			disablePatch()
@@ -3831,12 +3849,19 @@ func (s *OpenAIGatewayService) buildUpstreamRequest(ctx context.Context, c *gin.
 		}
 	}
 	if account.Type == AccountTypeOAuth {
+		compatMessagesBridge := isOpenAICompatMessagesBridgeContext(c) || isOpenAICompatMessagesBridgeBody(body)
 		// 清除客户端透传的 session 头，后续用隔离后的值重新设置，防止跨用户会话碰撞。
+		clientConversationID := strings.TrimSpace(req.Header.Get("conversation_id"))
 		req.Header.Del("conversation_id")
 		req.Header.Del("session_id")
 
-		req.Header.Set("OpenAI-Beta", "responses=experimental")
-		req.Header.Set("originator", resolveOpenAIUpstreamOriginator(c, isCodexCLI))
+		if compatMessagesBridge {
+			req.Header.Del("OpenAI-Beta")
+			req.Header.Del("originator")
+		} else {
+			req.Header.Set("OpenAI-Beta", "responses=experimental")
+			req.Header.Set("originator", resolveOpenAIUpstreamOriginator(c, isCodexCLI))
+		}
 		apiKeyID := getAPIKeyIDFromContext(c)
 		if isOpenAIResponsesCompactPath(c) {
 			req.Header.Set("accept", "application/json")
@@ -3850,8 +3875,10 @@ func (s *OpenAIGatewayService) buildUpstreamRequest(ctx context.Context, c *gin.
 		}
 		if promptCacheKey != "" {
 			isolated := isolateOpenAISessionID(apiKeyID, promptCacheKey)
-			req.Header.Set("conversation_id", isolated)
 			req.Header.Set("session_id", isolated)
+			if !compatMessagesBridge || clientConversationID != "" {
+				req.Header.Set("conversation_id", isolated)
+			}
 		}
 	}