merge upstream main

backend/internal/service/gemini_messages_compat_service.go

@@ -36,6 +36,11 @@ const (
 	geminiRetryMaxDelay  = 16 * time.Second
 )
 
+// Gemini tool calling now requires `thoughtSignature` in parts that include `functionCall`.
+// Many clients don't send it; we inject a known dummy signature to satisfy the validator.
+// Ref: https://ai.google.dev/gemini-api/docs/thought-signatures
+const geminiDummyThoughtSignature = "skip_thought_signature_validator"
+
 type GeminiMessagesCompatService struct {
 	accountRepo               AccountRepository
 	groupRepo                 GroupRepository
@@ -528,6 +533,7 @@ 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())
 	}
+	geminiReq = ensureGeminiFunctionCallThoughtSignatures(geminiReq)
 	originalClaudeBody := body
 
 	proxyURL := ""
@@ -983,6 +989,10 @@ func (s *GeminiMessagesCompatService) ForwardNative(ctx context.Context, c *gin.
 		return nil, s.writeGoogleError(c, http.StatusNotFound, "Unsupported action: "+action)
 	}
 
+	// Some Gemini upstreams validate tool call parts strictly; ensure any `functionCall` part includes a
+	// `thoughtSignature` to avoid frequent INVALID_ARGUMENT 400s.
+	body = ensureGeminiFunctionCallThoughtSignatures(body)
+
 	mappedModel := originalModel
 	if account.Type == AccountTypeAPIKey {
 		mappedModel = account.GetMappedModel(originalModel)
@@ -2662,6 +2672,58 @@ func nextGeminiDailyResetUnix() *int64 {
 	return &ts
 }
 
+func ensureGeminiFunctionCallThoughtSignatures(body []byte) []byte {
+	// Fast path: only run when functionCall is present.
+	if !bytes.Contains(body, []byte(`"functionCall"`)) {
+		return body
+	}
+
+	var payload map[string]any
+	if err := json.Unmarshal(body, &payload); err != nil {
+		return body
+	}
+
+	contentsAny, ok := payload["contents"].([]any)
+	if !ok || len(contentsAny) == 0 {
+		return body
+	}
+
+	modified := false
+	for _, c := range contentsAny {
+		cm, ok := c.(map[string]any)
+		if !ok {
+			continue
+		}
+		partsAny, ok := cm["parts"].([]any)
+		if !ok || len(partsAny) == 0 {
+			continue
+		}
+		for _, p := range partsAny {
+			pm, ok := p.(map[string]any)
+			if !ok || pm == nil {
+				continue
+			}
+			if fc, ok := pm["functionCall"].(map[string]any); !ok || fc == nil {
+				continue
+			}
+			ts, _ := pm["thoughtSignature"].(string)
+			if strings.TrimSpace(ts) == "" {
+				pm["thoughtSignature"] = geminiDummyThoughtSignature
+				modified = true
+			}
+		}
+	}
+
+	if !modified {
+		return body
+	}
+	b, err := json.Marshal(payload)
+	if err != nil {
+		return body
+	}
+	return b
+}
+
 func extractGeminiFinishReason(geminiResp map[string]any) string {
 	if candidates, ok := geminiResp["candidates"].([]any); ok && len(candidates) > 0 {
 		if cand, ok := candidates[0].(map[string]any); ok {
@@ -2861,7 +2923,13 @@ func convertClaudeMessagesToGeminiContents(messages any, toolUseIDToName map[str
 					if strings.TrimSpace(id) != "" && strings.TrimSpace(name) != "" {
 						toolUseIDToName[id] = name
 					}
+					signature, _ := bm["signature"].(string)
+					signature = strings.TrimSpace(signature)
+					if signature == "" {
+						signature = geminiDummyThoughtSignature
+					}
 					parts = append(parts, map[string]any{
+						"thoughtSignature": signature,
 						"functionCall": map[string]any{
 							"name": name,
 							"args": bm["input"],