Merge branch 'main' into test-dev

backend/internal/service/gemini_messages_compat_service.go

@@ -384,6 +384,7 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 	if err != nil {
 		return nil, s.writeClaudeError(c, http.StatusBadRequest, "invalid_request_error", err.Error())
 	}
+	originalClaudeBody := body
 
 	proxyURL := ""
 	if account.ProxyID != nil && account.Proxy != nil {
@@ -516,6 +517,7 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 	}
 
 	var resp *http.Response
+	signatureRetryStage := 0
 	for attempt := 1; attempt <= geminiMaxRetries; attempt++ {
 		upstreamReq, idHeader, err := buildReq(ctx)
 		if err != nil {
@@ -540,6 +542,46 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 			return nil, s.writeClaudeError(c, http.StatusBadGateway, "upstream_error", "Upstream request failed after retries: "+sanitizeUpstreamErrorMessage(err.Error()))
 		}
 
+		// Special-case: signature/thought_signature validation errors are not transient, but may be fixed by
+		// downgrading Claude thinking/tool history to plain text (conservative two-stage retry).
+		if resp.StatusCode == http.StatusBadRequest && signatureRetryStage < 2 {
+			respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
+			_ = resp.Body.Close()
+
+			if isGeminiSignatureRelatedError(respBody) {
+				var strippedClaudeBody []byte
+				stageName := ""
+				switch signatureRetryStage {
+				case 0:
+					// Stage 1: disable thinking + thinking->text
+					strippedClaudeBody = FilterThinkingBlocksForRetry(originalClaudeBody)
+					stageName = "thinking-only"
+					signatureRetryStage = 1
+				default:
+					// Stage 2: additionally downgrade tool_use/tool_result blocks to text
+					strippedClaudeBody = FilterSignatureSensitiveBlocksForRetry(originalClaudeBody)
+					stageName = "thinking+tools"
+					signatureRetryStage = 2
+				}
+				retryGeminiReq, txErr := convertClaudeMessagesToGeminiGenerateContent(strippedClaudeBody)
+				if txErr == nil {
+					log.Printf("Gemini account %d: detected signature-related 400, retrying with downgraded Claude blocks (%s)", account.ID, stageName)
+					geminiReq = retryGeminiReq
+					// Consume one retry budget attempt and continue with the updated request payload.
+					sleepGeminiBackoff(1)
+					continue
+				}
+			}
+
+			// Restore body for downstream error handling.
+			resp = &http.Response{
+				StatusCode: http.StatusBadRequest,
+				Header:     resp.Header.Clone(),
+				Body:       io.NopCloser(bytes.NewReader(respBody)),
+			}
+			break
+		}
+
 		if resp.StatusCode >= 400 && s.shouldRetryGeminiUpstreamError(account, resp.StatusCode) {
 			respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 2<<20))
 			_ = resp.Body.Close()
@@ -637,6 +679,14 @@ func (s *GeminiMessagesCompatService) Forward(ctx context.Context, c *gin.Contex
 	}, nil
 }
 
+func isGeminiSignatureRelatedError(respBody []byte) bool {
+	msg := strings.ToLower(strings.TrimSpace(extractAntigravityErrorMessage(respBody)))
+	if msg == "" {
+		msg = strings.ToLower(string(respBody))
+	}
+	return strings.Contains(msg, "thought_signature") || strings.Contains(msg, "signature")
+}
+
 func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.Context, account *Account, originalModel string, action string, stream bool, body []byte) (*ForwardResult, error) {
 	startTime := time.Now()