Fixed: #421

feat(antigravity): implement project ID retrieval and integration in payload processing

internal/api/modules/amp/routes.go

@@ -1,6 +1,7 @@
 package amp
 
 import (
+	"errors"
 	"net"
 	"net/http"
 	"net/http/httputil"
@@ -113,6 +114,17 @@ func (m *AmpModule) registerManagementRoutes(engine *gin.Engine, baseHandler *ha
 
 	// Dynamic proxy handler that uses m.getProxy() for hot-reload support
 	proxyHandler := func(c *gin.Context) {
+		// Swallow ErrAbortHandler panics from ReverseProxy copyResponse to avoid noisy stack traces
+		defer func() {
+			if rec := recover(); rec != nil {
+				if err, ok := rec.(error); ok && errors.Is(err, http.ErrAbortHandler) {
+					// Upstream already wrote the status (often 404) before the client/stream ended.
+					return
+				}
+				panic(rec)
+			}
+		}()
+
 		proxy := m.getProxy()
 		if proxy == nil {
 			c.JSON(503, gin.H{"error": "amp upstream proxy not available"})

internal/interfaces/client_models.go

@@ -85,6 +85,9 @@ type InlineData struct {
 // FunctionCall represents a tool call requested by the model.
 // It includes the function name and its arguments that the model wants to execute.
 type FunctionCall struct {
+	// ID is the identifier of the function to be called.
+	ID string `json:"id,omitempty"`
+
 	// Name is the identifier of the function to be called.
 	Name string `json:"name"`
 
@@ -95,6 +98,9 @@ type FunctionCall struct {
 // FunctionResponse represents the result of a tool execution.
 // This is sent back to the model after a tool call has been processed.
 type FunctionResponse struct {
+	// ID is the identifier of the function to be called.
+	ID string `json:"id,omitempty"`
+
 	// Name is the identifier of the function that was called.
 	Name string `json:"name"`
 

internal/runtime/executor/antigravity_executor.go

@@ -509,7 +509,14 @@ func (e *AntigravityExecutor) buildRequest(ctx context.Context, auth *cliproxyau
 		requestURL.WriteString(url.QueryEscape(alt))
 	}
 
-	payload = geminiToAntigravity(modelName, payload)
+	// Extract project_id from auth metadata if available
+	projectID := ""
+	if auth != nil && auth.Metadata != nil {
+		if pid, ok := auth.Metadata["project_id"].(string); ok {
+			projectID = strings.TrimSpace(pid)
+		}
+	}
+	payload = geminiToAntigravity(modelName, payload, projectID)
 	payload, _ = sjson.SetBytes(payload, "model", alias2ModelName(modelName))
 
 	if strings.Contains(modelName, "claude") {
@@ -676,9 +683,9 @@ func antigravityBaseURLFallbackOrder(auth *cliproxyauth.Auth) []string {
 		return []string{base}
 	}
 	return []string{
+		antigravityBaseURLProd,
 		antigravityBaseURLDaily,
 		antigravityBaseURLAutopush,
-		// antigravityBaseURLProd,
 	}
 }
 
@@ -702,10 +709,16 @@ func resolveCustomAntigravityBaseURL(auth *cliproxyauth.Auth) string {
 	return ""
 }
 
-func geminiToAntigravity(modelName string, payload []byte) []byte {
+func geminiToAntigravity(modelName string, payload []byte, projectID string) []byte {
 	template, _ := sjson.Set(string(payload), "model", modelName)
 	template, _ = sjson.Set(template, "userAgent", "antigravity")
-	template, _ = sjson.Set(template, "project", generateProjectID())
+
+	// Use real project ID from auth if available, otherwise generate random (legacy fallback)
+	if projectID != "" {
+		template, _ = sjson.Set(template, "project", projectID)
+	} else {
+		template, _ = sjson.Set(template, "project", generateProjectID())
+	}
 	template, _ = sjson.Set(template, "requestId", generateRequestID())
 	template, _ = sjson.Set(template, "request.sessionId", generateSessionID())
 

internal/translator/antigravity/claude/antigravity_claude_request.go

@@ -89,10 +89,11 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 					} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "tool_use" {
 						functionName := contentResult.Get("name").String()
 						functionArgs := contentResult.Get("input").String()
+						functionID := contentResult.Get("id").String()
 						var args map[string]any
 						if err := json.Unmarshal([]byte(functionArgs), &args); err == nil {
 							clientContent.Parts = append(clientContent.Parts, client.Part{
-								FunctionCall:     &client.FunctionCall{Name: functionName, Args: args},
+								FunctionCall:     &client.FunctionCall{ID: functionID, Name: functionName, Args: args},
 								ThoughtSignature: geminiCLIClaudeThoughtSignature,
 							})
 						}
@@ -105,7 +106,7 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 								funcName = strings.Join(toolCallIDs[0:len(toolCallIDs)-1], "-")
 							}
 							responseData := contentResult.Get("content").Raw
-							functionResponse := client.FunctionResponse{Name: funcName, Response: map[string]interface{}{"result": responseData}}
+							functionResponse := client.FunctionResponse{ID: toolCallID, Name: funcName, Response: map[string]interface{}{"result": responseData}}
 							clientContent.Parts = append(clientContent.Parts, client.Part{FunctionResponse: &functionResponse})
 						}
 					}

internal/translator/antigravity/claude/antigravity_claude_response.go

@@ -141,35 +141,38 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 						params.ResponseType = 2 // Set state to thinking
 					}
 				} else {
-					// Process regular text content (user-visible output)
-					// Continue existing text block if already in content state
-					if params.ResponseType == 1 {
-						output = output + "event: content_block_delta\n"
-						data, _ := sjson.Set(fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, params.ResponseIndex), "delta.text", partTextResult.String())
-						output = output + fmt.Sprintf("data: %s\n\n\n", data)
-					} else {
-						// Transition from another state to text content
-						// First, close any existing content block
-						if params.ResponseType != 0 {
-							if params.ResponseType == 2 {
-								// output = output + "event: content_block_delta\n"
-								// output = output + fmt.Sprintf(`data: {"type":"content_block_delta","index":%d,"delta":{"type":"signature_delta","signature":null}}`, params.ResponseIndex)
-								// output = output + "\n\n\n"
+					finishReasonResult := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason")
+					if partTextResult.String() != "" || !finishReasonResult.Exists() {
+						// Process regular text content (user-visible output)
+						// Continue existing text block if already in content state
+						if params.ResponseType == 1 {
+							output = output + "event: content_block_delta\n"
+							data, _ := sjson.Set(fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, params.ResponseIndex), "delta.text", partTextResult.String())
+							output = output + fmt.Sprintf("data: %s\n\n\n", data)
+						} else {
+							// Transition from another state to text content
+							// First, close any existing content block
+							if params.ResponseType != 0 {
+								if params.ResponseType == 2 {
+									// output = output + "event: content_block_delta\n"
+									// output = output + fmt.Sprintf(`data: {"type":"content_block_delta","index":%d,"delta":{"type":"signature_delta","signature":null}}`, params.ResponseIndex)
+									// output = output + "\n\n\n"
+								}
+								output = output + "event: content_block_stop\n"
+								output = output + fmt.Sprintf(`data: {"type":"content_block_stop","index":%d}`, params.ResponseIndex)
+								output = output + "\n\n\n"
+								params.ResponseIndex++
 							}
-							output = output + "event: content_block_stop\n"
-							output = output + fmt.Sprintf(`data: {"type":"content_block_stop","index":%d}`, params.ResponseIndex)
-							output = output + "\n\n\n"
-							params.ResponseIndex++
-						}
 
-						// Start a new text content block
-						output = output + "event: content_block_start\n"
-						output = output + fmt.Sprintf(`data: {"type":"content_block_start","index":%d,"content_block":{"type":"text","text":""}}`, params.ResponseIndex)
-						output = output + "\n\n\n"
-						output = output + "event: content_block_delta\n"
-						data, _ := sjson.Set(fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, params.ResponseIndex), "delta.text", partTextResult.String())
-						output = output + fmt.Sprintf("data: %s\n\n\n", data)
-						params.ResponseType = 1 // Set state to content
+							// Start a new text content block
+							output = output + "event: content_block_start\n"
+							output = output + fmt.Sprintf(`data: {"type":"content_block_start","index":%d,"content_block":{"type":"text","text":""}}`, params.ResponseIndex)
+							output = output + "\n\n\n"
+							output = output + "event: content_block_delta\n"
+							data, _ := sjson.Set(fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, params.ResponseIndex), "delta.text", partTextResult.String())
+							output = output + fmt.Sprintf("data: %s\n\n\n", data)
+							params.ResponseType = 1 // Set state to content
+						}
 					}
 				}
 			} else if functionCallResult.Exists() {

internal/translator/antigravity/openai/chat-completions/antigravity_openai_request.go

@@ -251,6 +251,7 @@ func ConvertOpenAIRequestToAntigravity(modelName string, inputRawJSON []byte, _
 							fid := tc.Get("id").String()
 							fname := tc.Get("function.name").String()
 							fargs := tc.Get("function.arguments").String()
+							node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.id", fid)
 							node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".functionCall.name", fname)
 							node, _ = sjson.SetRawBytes(node, "parts."+itoa(p)+".functionCall.args", []byte(fargs))
 							node, _ = sjson.SetBytes(node, "parts."+itoa(p)+".thoughtSignature", geminiCLIFunctionThoughtSignature)
@@ -266,6 +267,7 @@ func ConvertOpenAIRequestToAntigravity(modelName string, inputRawJSON []byte, _
 						pp := 0
 						for _, fid := range fIDs {
 							if name, ok := tcID2Name[fid]; ok {
+								toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.id", fid)
 								toolNode, _ = sjson.SetBytes(toolNode, "parts."+itoa(pp)+".functionResponse.name", name)
 								resp := toolResponses[fid]
 								if resp == "" {

internal/translator/codex/gemini/codex_gemini_response.go

@@ -327,7 +327,7 @@ func buildReverseMapFromGeminiOriginal(original []byte) map[string]string {
 func mustMarshalJSON(v interface{}) string {
 	data, err := json.Marshal(v)
 	if err != nil {
-		panic(err)
+		return ""
 	}
 	return string(data)
 }

internal/translator/gemini/openai/responses/gemini_openai-responses_request.go

@@ -249,6 +249,7 @@ func ConvertOpenAIResponsesRequestToGemini(modelName string, inputRawJSON []byte
 				functionCall := `{"functionCall":{"name":"","args":{}}}`
 				functionCall, _ = sjson.Set(functionCall, "functionCall.name", name)
 				functionCall, _ = sjson.Set(functionCall, "thoughtSignature", geminiResponsesThoughtSignature)
+				functionCall, _ = sjson.Set(functionCall, "functionCall.id", item.Get("call_id").String())
 
 				// Parse arguments JSON string and set as args object
 				if arguments != "" {
@@ -285,6 +286,7 @@ func ConvertOpenAIResponsesRequestToGemini(modelName string, inputRawJSON []byte
 				}
 
 				functionResponse, _ = sjson.Set(functionResponse, "functionResponse.name", functionName)
+				functionResponse, _ = sjson.Set(functionResponse, "functionResponse.id", callID)
 
 				// Set the raw JSON output directly (preserves string encoding)
 				if outputRaw != "" && outputRaw != "null" {

sdk/auth/antigravity.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -127,6 +128,18 @@ func (AntigravityAuthenticator) Login(ctx context.Context, cfg *config.Config, o
 		}
 	}
 
+	// Fetch project ID via loadCodeAssist (same approach as Gemini CLI)
+	projectID := ""
+	if tokenResp.AccessToken != "" {
+		fetchedProjectID, errProject := fetchAntigravityProjectID(ctx, tokenResp.AccessToken, httpClient)
+		if errProject != nil {
+			log.Warnf("antigravity: failed to fetch project ID: %v", errProject)
+		} else {
+			projectID = fetchedProjectID
+			log.Infof("antigravity: obtained project ID %s", projectID)
+		}
+	}
+
 	now := time.Now()
 	metadata := map[string]any{
 		"type":          "antigravity",
@@ -139,6 +152,9 @@ func (AntigravityAuthenticator) Login(ctx context.Context, cfg *config.Config, o
 	if email != "" {
 		metadata["email"] = email
 	}
+	if projectID != "" {
+		metadata["project_id"] = projectID
+	}
 
 	fileName := sanitizeAntigravityFileName(email)
 	label := email
@@ -147,6 +163,9 @@ func (AntigravityAuthenticator) Login(ctx context.Context, cfg *config.Config, o
 	}
 
 	fmt.Println("Antigravity authentication successful")
+	if projectID != "" {
+		fmt.Printf("Using GCP project: %s\n", projectID)
+	}
 	return &coreauth.Auth{
 		ID:       fileName,
 		Provider: "antigravity",
@@ -291,3 +310,84 @@ func sanitizeAntigravityFileName(email string) string {
 	replacer := strings.NewReplacer("@", "_", ".", "_")
 	return fmt.Sprintf("antigravity-%s.json", replacer.Replace(email))
 }
+
+// Antigravity API constants for project discovery
+const (
+	antigravityAPIEndpoint    = "https://cloudcode-pa.googleapis.com"
+	antigravityAPIVersion     = "v1internal"
+	antigravityAPIUserAgent   = "google-api-nodejs-client/9.15.1"
+	antigravityAPIClient      = "google-cloud-sdk vscode_cloudshelleditor/0.1"
+	antigravityClientMetadata = `{"ideType":"IDE_UNSPECIFIED","platform":"PLATFORM_UNSPECIFIED","pluginType":"GEMINI"}`
+)
+
+// fetchAntigravityProjectID retrieves the project ID for the authenticated user via loadCodeAssist.
+// This uses the same approach as Gemini CLI to get the cloudaicompanionProject.
+func fetchAntigravityProjectID(ctx context.Context, accessToken string, httpClient *http.Client) (string, error) {
+	// Call loadCodeAssist to get the project
+	loadReqBody := map[string]any{
+		"metadata": map[string]string{
+			"ideType":    "IDE_UNSPECIFIED",
+			"platform":   "PLATFORM_UNSPECIFIED",
+			"pluginType": "GEMINI",
+		},
+	}
+
+	rawBody, errMarshal := json.Marshal(loadReqBody)
+	if errMarshal != nil {
+		return "", fmt.Errorf("marshal request body: %w", errMarshal)
+	}
+
+	endpointURL := fmt.Sprintf("%s/%s:loadCodeAssist", antigravityAPIEndpoint, antigravityAPIVersion)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpointURL, strings.NewReader(string(rawBody)))
+	if err != nil {
+		return "", fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", antigravityAPIUserAgent)
+	req.Header.Set("X-Goog-Api-Client", antigravityAPIClient)
+	req.Header.Set("Client-Metadata", antigravityClientMetadata)
+
+	resp, errDo := httpClient.Do(req)
+	if errDo != nil {
+		return "", fmt.Errorf("execute request: %w", errDo)
+	}
+	defer func() {
+		if errClose := resp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity loadCodeAssist: close body error: %v", errClose)
+		}
+	}()
+
+	bodyBytes, errRead := io.ReadAll(resp.Body)
+	if errRead != nil {
+		return "", fmt.Errorf("read response: %w", errRead)
+	}
+
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+		return "", fmt.Errorf("request failed with status %d: %s", resp.StatusCode, strings.TrimSpace(string(bodyBytes)))
+	}
+
+	var loadResp map[string]any
+	if errDecode := json.Unmarshal(bodyBytes, &loadResp); errDecode != nil {
+		return "", fmt.Errorf("decode response: %w", errDecode)
+	}
+
+	// Extract projectID from response
+	projectID := ""
+	if id, ok := loadResp["cloudaicompanionProject"].(string); ok {
+		projectID = strings.TrimSpace(id)
+	}
+	if projectID == "" {
+		if projectMap, ok := loadResp["cloudaicompanionProject"].(map[string]any); ok {
+			if id, okID := projectMap["id"].(string); okID {
+				projectID = strings.TrimSpace(id)
+			}
+		}
+	}
+
+	if projectID == "" {
+		return "", fmt.Errorf("no cloudaicompanionProject in response")
+	}
+
+	return projectID, nil
+}