**refactor(auth): use customizable HTTP client for Antigravity requests**

- Replaced `http.DefaultClient` with a configurable `http.Client` instance for Antigravity OAuth flow methods.
- Updated `exchangeAntigravityCode` and `fetchAntigravityUserInfo` to accept `httpClient` as a parameter.
- Added `util.SetProxy` usage to initialize the `httpClient` with proxy support.

cmd/server/main.go

@@ -61,6 +61,7 @@ func main() {
 	var iflowLogin bool
 	var iflowCookie bool
 	var noBrowser bool
+	var antigravityLogin bool
 	var projectID string
 	var vertexImport string
 	var configPath string
@@ -74,6 +75,7 @@ func main() {
 	flag.BoolVar(&iflowLogin, "iflow-login", false, "Login to iFlow using OAuth")
 	flag.BoolVar(&iflowCookie, "iflow-cookie", false, "Login to iFlow using Cookie")
 	flag.BoolVar(&noBrowser, "no-browser", false, "Don't open browser automatically for OAuth")
+	flag.BoolVar(&antigravityLogin, "antigravity-login", false, "Login to Antigravity using OAuth")
 	flag.StringVar(&projectID, "project_id", "", "Project ID (Gemini only, not required)")
 	flag.StringVar(&configPath, "config", DefaultConfigPath, "Configure File Path")
 	flag.StringVar(&vertexImport, "vertex-import", "", "Import Vertex service account key JSON file")
@@ -431,6 +433,9 @@ func main() {
 	} else if login {
 		// Handle Google/Gemini login
 		cmd.DoLogin(cfg, projectID, options)
+	} else if antigravityLogin {
+		// Handle Antigravity login
+		cmd.DoAntigravityLogin(cfg, options)
 	} else if codexLogin {
 		// Handle Codex login
 		cmd.DoCodexLogin(cfg, options)

docker-compose.yml

@@ -19,6 +19,7 @@ services:
       - "8085:8085"
       - "1455:1455"
       - "54545:54545"
+      - "51121:51121"
       - "11451:11451"
     volumes:
       - ./config.yaml:/CLIProxyAPI/config.yaml

internal/cmd/antigravity_login.go

@@ -0,0 +1,38 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	sdkAuth "github.com/router-for-me/CLIProxyAPI/v6/sdk/auth"
+	log "github.com/sirupsen/logrus"
+)
+
+// DoAntigravityLogin triggers the OAuth flow for the antigravity provider and saves tokens.
+func DoAntigravityLogin(cfg *config.Config, options *LoginOptions) {
+	if options == nil {
+		options = &LoginOptions{}
+	}
+
+	manager := newAuthManager()
+	authOpts := &sdkAuth.LoginOptions{
+		NoBrowser: options.NoBrowser,
+		Metadata:  map[string]string{},
+		Prompt:    options.Prompt,
+	}
+
+	record, savedPath, err := manager.Login(context.Background(), "antigravity", cfg, authOpts)
+	if err != nil {
+		log.Errorf("Antigravity authentication failed: %v", err)
+		return
+	}
+
+	if savedPath != "" {
+		fmt.Printf("Authentication saved to %s\n", savedPath)
+	}
+	if record != nil && record.Label != "" {
+		fmt.Printf("Authenticated as %s\n", record.Label)
+	}
+	fmt.Println("Antigravity authentication successful!")
+}

internal/cmd/auth_manager.go

@@ -18,6 +18,7 @@ func newAuthManager() *sdkAuth.Manager {
 		sdkAuth.NewClaudeAuthenticator(),
 		sdkAuth.NewQwenAuthenticator(),
 		sdkAuth.NewIFlowAuthenticator(),
+		sdkAuth.NewAntigravityAuthenticator(),
 	)
 	return manager
 }

internal/runtime/executor/aistudio_executor.go

@@ -151,7 +151,7 @@ func (e *AIStudioExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth
 			case wsrelay.MessageTypeStreamChunk:
 				if len(event.Payload) > 0 {
 					appendAPIResponseChunk(ctx, e.cfg, bytes.Clone(event.Payload))
-					filtered := filterAIStudioUsageMetadata(event.Payload)
+					filtered := FilterSSEUsageMetadata(event.Payload)
 					if detail, ok := parseGeminiStreamUsage(filtered); ok {
 						reporter.publish(ctx, detail)
 					}
@@ -264,6 +264,7 @@ func (e *AIStudioExecutor) translateRequest(req cliproxyexecutor.Request, opts c
 		}
 		payload = util.ApplyGeminiThinkingConfig(payload, budgetOverride, includeOverride)
 	}
+	payload = util.ConvertThinkingLevelToBudget(payload)
 	payload = util.StripThinkingConfigIfUnsupported(req.Model, payload)
 	payload = fixGeminiImageAspectRatio(req.Model, payload)
 	payload = applyPayloadConfig(e.cfg, req.Model, payload)
@@ -295,65 +296,6 @@ func (e *AIStudioExecutor) buildEndpoint(model, action, alt string) string {
 	return base
 }
 
-// filterAIStudioUsageMetadata removes usageMetadata from intermediate SSE events so that
-// only the terminal chunk retains token statistics.
-func filterAIStudioUsageMetadata(payload []byte) []byte {
-	if len(payload) == 0 {
-		return payload
-	}
-
-	lines := bytes.Split(payload, []byte("\n"))
-	modified := false
-	for idx, line := range lines {
-		trimmed := bytes.TrimSpace(line)
-		if len(trimmed) == 0 || !bytes.HasPrefix(trimmed, []byte("data:")) {
-			continue
-		}
-		dataIdx := bytes.Index(line, []byte("data:"))
-		if dataIdx < 0 {
-			continue
-		}
-		rawJSON := bytes.TrimSpace(line[dataIdx+5:])
-		cleaned, changed := stripUsageMetadataFromJSON(rawJSON)
-		if !changed {
-			continue
-		}
-		var rebuilt []byte
-		rebuilt = append(rebuilt, line[:dataIdx]...)
-		rebuilt = append(rebuilt, []byte("data:")...)
-		if len(cleaned) > 0 {
-			rebuilt = append(rebuilt, ' ')
-			rebuilt = append(rebuilt, cleaned...)
-		}
-		lines[idx] = rebuilt
-		modified = true
-	}
-	if !modified {
-		return payload
-	}
-	return bytes.Join(lines, []byte("\n"))
-}
-
-// stripUsageMetadataFromJSON drops usageMetadata when no finishReason is present.
-func stripUsageMetadataFromJSON(rawJSON []byte) ([]byte, bool) {
-	jsonBytes := bytes.TrimSpace(rawJSON)
-	if len(jsonBytes) == 0 || !gjson.ValidBytes(jsonBytes) {
-		return rawJSON, false
-	}
-	finishReason := gjson.GetBytes(jsonBytes, "candidates.0.finishReason")
-	if finishReason.Exists() && finishReason.String() != "" {
-		return rawJSON, false
-	}
-	if !gjson.GetBytes(jsonBytes, "usageMetadata").Exists() {
-		return rawJSON, false
-	}
-	cleaned, err := sjson.DeleteBytes(jsonBytes, "usageMetadata")
-	if err != nil {
-		return rawJSON, false
-	}
-	return cleaned, true
-}
-
 // ensureColonSpacedJSON normalizes JSON objects so that colons are followed by a single space while
 // keeping the payload otherwise compact. Non-JSON inputs are returned unchanged.
 func ensureColonSpacedJSON(payload []byte) []byte {

internal/runtime/executor/antigravity_executor.go

@@ -0,0 +1,565 @@
+package executor
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math/rand"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
+	cliproxyexecutor "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/executor"
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v6/sdk/translator"
+	log "github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+const (
+	antigravityBaseURL          = "https://daily-cloudcode-pa.sandbox.googleapis.com"
+	antigravityStreamPath       = "/v1internal:streamGenerateContent"
+	antigravityGeneratePath     = "/v1internal:generateContent"
+	antigravityModelsPath       = "/v1internal:fetchAvailableModels"
+	antigravityClientID         = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
+	antigravityClientSecret     = "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"
+	defaultAntigravityAgent     = "antigravity/1.11.3 windows/amd64"
+	antigravityAuthType         = "antigravity"
+	refreshSkew                 = 5 * time.Minute
+	streamScannerBuffer     int = 20_971_520
+)
+
+var randSource = rand.New(rand.NewSource(time.Now().UnixNano()))
+
+// AntigravityExecutor proxies requests to the antigravity upstream.
+type AntigravityExecutor struct {
+	cfg *config.Config
+}
+
+// NewAntigravityExecutor constructs a new executor instance.
+func NewAntigravityExecutor(cfg *config.Config) *AntigravityExecutor {
+	return &AntigravityExecutor{cfg: cfg}
+}
+
+// Identifier implements ProviderExecutor.
+func (e *AntigravityExecutor) Identifier() string { return antigravityAuthType }
+
+// PrepareRequest implements ProviderExecutor.
+func (e *AntigravityExecutor) PrepareRequest(_ *http.Request, _ *cliproxyauth.Auth) error { return nil }
+
+// Execute handles non-streaming requests via the antigravity generate endpoint.
+func (e *AntigravityExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (resp cliproxyexecutor.Response, err error) {
+	token, updatedAuth, errToken := e.ensureAccessToken(ctx, auth)
+	if errToken != nil {
+		return resp, errToken
+	}
+	if updatedAuth != nil {
+		auth = updatedAuth
+	}
+
+	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
+	defer reporter.trackFailure(ctx, &err)
+
+	from := opts.SourceFormat
+	to := sdktranslator.FromString("gemini-cli")
+	translated := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), false)
+
+	httpReq, errReq := e.buildRequest(ctx, auth, token, req.Model, translated, false, opts.Alt)
+	if errReq != nil {
+		return resp, errReq
+	}
+
+	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
+	httpResp, errDo := httpClient.Do(httpReq)
+	if errDo != nil {
+		recordAPIResponseError(ctx, e.cfg, errDo)
+		return resp, errDo
+	}
+	defer func() {
+		if errClose := httpResp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity executor: close response body error: %v", errClose)
+		}
+	}()
+
+	recordAPIResponseMetadata(ctx, e.cfg, httpResp.StatusCode, httpResp.Header.Clone())
+	bodyBytes, errRead := io.ReadAll(httpResp.Body)
+	if errRead != nil {
+		recordAPIResponseError(ctx, e.cfg, errRead)
+		return resp, errRead
+	}
+	appendAPIResponseChunk(ctx, e.cfg, bodyBytes)
+
+	if httpResp.StatusCode < http.StatusOK || httpResp.StatusCode >= http.StatusMultipleChoices {
+		log.Debugf("antigravity executor: upstream error status: %d, body: %s", httpResp.StatusCode, summarizeErrorBody(httpResp.Header.Get("Content-Type"), bodyBytes))
+		err = statusErr{code: httpResp.StatusCode, msg: string(bodyBytes)}
+		return resp, err
+	}
+
+	var param any
+	converted := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, bodyBytes, &param)
+	resp = cliproxyexecutor.Response{Payload: []byte(converted)}
+	reporter.ensurePublished(ctx)
+	return resp, nil
+}
+
+// ExecuteStream handles streaming requests via the antigravity upstream.
+func (e *AntigravityExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (stream <-chan cliproxyexecutor.StreamChunk, err error) {
+	ctx = context.WithValue(ctx, "alt", "")
+
+	token, updatedAuth, errToken := e.ensureAccessToken(ctx, auth)
+	if errToken != nil {
+		return nil, errToken
+	}
+	if updatedAuth != nil {
+		auth = updatedAuth
+	}
+
+	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
+	defer reporter.trackFailure(ctx, &err)
+
+	from := opts.SourceFormat
+	to := sdktranslator.FromString("gemini-cli")
+	translated := sdktranslator.TranslateRequest(from, to, req.Model, bytes.Clone(req.Payload), true)
+
+	httpReq, errReq := e.buildRequest(ctx, auth, token, req.Model, translated, true, opts.Alt)
+	if errReq != nil {
+		return nil, errReq
+	}
+
+	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
+	httpResp, errDo := httpClient.Do(httpReq)
+	if errDo != nil {
+		recordAPIResponseError(ctx, e.cfg, errDo)
+		return nil, errDo
+	}
+	recordAPIResponseMetadata(ctx, e.cfg, httpResp.StatusCode, httpResp.Header.Clone())
+	if httpResp.StatusCode < http.StatusOK || httpResp.StatusCode >= http.StatusMultipleChoices {
+		bodyBytes, _ := io.ReadAll(httpResp.Body)
+		appendAPIResponseChunk(ctx, e.cfg, bodyBytes)
+		if errClose := httpResp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity executor: close response body error: %v", errClose)
+		}
+		err = statusErr{code: httpResp.StatusCode, msg: string(bodyBytes)}
+		return nil, err
+	}
+
+	out := make(chan cliproxyexecutor.StreamChunk)
+	stream = out
+	go func() {
+		defer close(out)
+		defer func() {
+			if errClose := httpResp.Body.Close(); errClose != nil {
+				log.Errorf("antigravity executor: close response body error: %v", errClose)
+			}
+		}()
+		scanner := bufio.NewScanner(httpResp.Body)
+		scanner.Buffer(nil, streamScannerBuffer)
+		var param any
+		for scanner.Scan() {
+			line := scanner.Bytes()
+			appendAPIResponseChunk(ctx, e.cfg, line)
+
+			// Filter usage metadata for all models
+			// Only retain usage statistics in the terminal chunk
+			line = FilterSSEUsageMetadata(line)
+
+			chunks := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, bytes.Clone(line), &param)
+			for i := range chunks {
+				out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunks[i])}
+			}
+		}
+		tail := sdktranslator.TranslateStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), translated, []byte("[DONE]"), &param)
+		for i := range tail {
+			out <- cliproxyexecutor.StreamChunk{Payload: []byte(tail[i])}
+		}
+		if errScan := scanner.Err(); errScan != nil {
+			recordAPIResponseError(ctx, e.cfg, errScan)
+			reporter.publishFailure(ctx)
+			out <- cliproxyexecutor.StreamChunk{Err: errScan}
+		} else {
+			reporter.ensurePublished(ctx)
+		}
+	}()
+	return stream, nil
+}
+
+// Refresh refreshes the OAuth token using the refresh token.
+func (e *AntigravityExecutor) Refresh(ctx context.Context, auth *cliproxyauth.Auth) (*cliproxyauth.Auth, error) {
+	if auth == nil {
+		return auth, nil
+	}
+	updated, errRefresh := e.refreshToken(ctx, auth.Clone())
+	if errRefresh != nil {
+		return nil, errRefresh
+	}
+	return updated, nil
+}
+
+// CountTokens is not supported for the antigravity provider.
+func (e *AntigravityExecutor) CountTokens(context.Context, *cliproxyauth.Auth, cliproxyexecutor.Request, cliproxyexecutor.Options) (cliproxyexecutor.Response, error) {
+	return cliproxyexecutor.Response{}, statusErr{code: http.StatusNotImplemented, msg: "count tokens not supported"}
+}
+
+// FetchAntigravityModels retrieves available models using the supplied auth.
+func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *config.Config) []*registry.ModelInfo {
+	exec := &AntigravityExecutor{cfg: cfg}
+	token, updatedAuth, errToken := exec.ensureAccessToken(ctx, auth)
+	if errToken != nil || token == "" {
+		return nil
+	}
+	if updatedAuth != nil {
+		auth = updatedAuth
+	}
+
+	modelsURL := buildBaseURL(auth) + antigravityModelsPath
+	httpReq, errReq := http.NewRequestWithContext(ctx, http.MethodPost, modelsURL, bytes.NewReader([]byte(`{}`)))
+	if errReq != nil {
+		return nil
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("Authorization", "Bearer "+token)
+	httpReq.Header.Set("User-Agent", resolveUserAgent(auth))
+	if host := resolveHost(auth); host != "" {
+		httpReq.Host = host
+	}
+
+	httpClient := newProxyAwareHTTPClient(ctx, cfg, auth, 0)
+	httpResp, errDo := httpClient.Do(httpReq)
+	if errDo != nil {
+		return nil
+	}
+	defer func() {
+		if errClose := httpResp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity executor: close response body error: %v", errClose)
+		}
+	}()
+
+	bodyBytes, errRead := io.ReadAll(httpResp.Body)
+	if errRead != nil {
+		return nil
+	}
+	if httpResp.StatusCode < http.StatusOK || httpResp.StatusCode >= http.StatusMultipleChoices {
+		return nil
+	}
+
+	result := gjson.GetBytes(bodyBytes, "models")
+	if !result.Exists() {
+		return nil
+	}
+
+	now := time.Now().Unix()
+	models := make([]*registry.ModelInfo, 0, len(result.Map()))
+	for id := range result.Map() {
+		models = append(models, &registry.ModelInfo{
+			ID:      id,
+			Object:  "model",
+			Created: now,
+			OwnedBy: antigravityAuthType,
+			Type:    antigravityAuthType,
+		})
+	}
+	return models
+}
+
+func (e *AntigravityExecutor) ensureAccessToken(ctx context.Context, auth *cliproxyauth.Auth) (string, *cliproxyauth.Auth, error) {
+	if auth == nil {
+		return "", nil, statusErr{code: http.StatusUnauthorized, msg: "missing auth"}
+	}
+	accessToken := metaStringValue(auth.Metadata, "access_token")
+	expiry := tokenExpiry(auth.Metadata)
+	if accessToken != "" && expiry.After(time.Now().Add(refreshSkew)) {
+		return accessToken, nil, nil
+	}
+	updated, errRefresh := e.refreshToken(ctx, auth.Clone())
+	if errRefresh != nil {
+		return "", nil, errRefresh
+	}
+	return metaStringValue(updated.Metadata, "access_token"), updated, nil
+}
+
+func (e *AntigravityExecutor) refreshToken(ctx context.Context, auth *cliproxyauth.Auth) (*cliproxyauth.Auth, error) {
+	if auth == nil {
+		return nil, statusErr{code: http.StatusUnauthorized, msg: "missing auth"}
+	}
+	refreshToken := metaStringValue(auth.Metadata, "refresh_token")
+	if refreshToken == "" {
+		return auth, statusErr{code: http.StatusUnauthorized, msg: "missing refresh token"}
+	}
+
+	form := url.Values{}
+	form.Set("client_id", antigravityClientID)
+	form.Set("client_secret", antigravityClientSecret)
+	form.Set("grant_type", "refresh_token")
+	form.Set("refresh_token", refreshToken)
+
+	httpReq, errReq := http.NewRequestWithContext(ctx, http.MethodPost, "https://oauth2.googleapis.com/token", strings.NewReader(form.Encode()))
+	if errReq != nil {
+		return auth, errReq
+	}
+	httpReq.Header.Set("Host", "oauth2.googleapis.com")
+	httpReq.Header.Set("User-Agent", defaultAntigravityAgent)
+	httpReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	httpClient := newProxyAwareHTTPClient(ctx, e.cfg, auth, 0)
+	httpResp, errDo := httpClient.Do(httpReq)
+	if errDo != nil {
+		return auth, errDo
+	}
+	defer func() {
+		if errClose := httpResp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity executor: close response body error: %v", errClose)
+		}
+	}()
+
+	bodyBytes, errRead := io.ReadAll(httpResp.Body)
+	if errRead != nil {
+		return auth, errRead
+	}
+
+	if httpResp.StatusCode < http.StatusOK || httpResp.StatusCode >= http.StatusMultipleChoices {
+		return auth, statusErr{code: httpResp.StatusCode, msg: string(bodyBytes)}
+	}
+
+	var tokenResp struct {
+		AccessToken  string `json:"access_token"`
+		RefreshToken string `json:"refresh_token"`
+		ExpiresIn    int64  `json:"expires_in"`
+		TokenType    string `json:"token_type"`
+	}
+	if errUnmarshal := json.Unmarshal(bodyBytes, &tokenResp); errUnmarshal != nil {
+		return auth, errUnmarshal
+	}
+
+	if auth.Metadata == nil {
+		auth.Metadata = make(map[string]any)
+	}
+	auth.Metadata["access_token"] = tokenResp.AccessToken
+	if tokenResp.RefreshToken != "" {
+		auth.Metadata["refresh_token"] = tokenResp.RefreshToken
+	}
+	auth.Metadata["expires_in"] = tokenResp.ExpiresIn
+	auth.Metadata["timestamp"] = time.Now().UnixMilli()
+	auth.Metadata["expired"] = time.Now().Add(time.Duration(tokenResp.ExpiresIn) * time.Second).Format(time.RFC3339)
+	auth.Metadata["type"] = antigravityAuthType
+	return auth, nil
+}
+
+func (e *AntigravityExecutor) buildRequest(ctx context.Context, auth *cliproxyauth.Auth, token, modelName string, payload []byte, stream bool, alt string) (*http.Request, error) {
+	if token == "" {
+		return nil, statusErr{code: http.StatusUnauthorized, msg: "missing access token"}
+	}
+
+	base := buildBaseURL(auth)
+	path := antigravityGeneratePath
+	if stream {
+		path = antigravityStreamPath
+	}
+	var requestURL strings.Builder
+	requestURL.WriteString(base)
+	requestURL.WriteString(path)
+	if stream {
+		if alt != "" {
+			requestURL.WriteString("?$alt=")
+			requestURL.WriteString(url.QueryEscape(alt))
+		} else {
+			requestURL.WriteString("?alt=sse")
+		}
+	} else if alt != "" {
+		requestURL.WriteString("?$alt=")
+		requestURL.WriteString(url.QueryEscape(alt))
+	}
+
+	payload = geminiToAntigravity(modelName, payload)
+	httpReq, errReq := http.NewRequestWithContext(ctx, http.MethodPost, requestURL.String(), bytes.NewReader(payload))
+	if errReq != nil {
+		return nil, errReq
+	}
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("Authorization", "Bearer "+token)
+	httpReq.Header.Set("User-Agent", resolveUserAgent(auth))
+	if stream {
+		httpReq.Header.Set("Accept", "text/event-stream")
+	} else {
+		httpReq.Header.Set("Accept", "application/json")
+	}
+	if host := resolveHost(auth); host != "" {
+		httpReq.Host = host
+	}
+
+	var authID, authLabel, authType, authValue string
+	if auth != nil {
+		authID = auth.ID
+		authLabel = auth.Label
+		authType, authValue = auth.AccountInfo()
+	}
+	recordAPIRequest(ctx, e.cfg, upstreamRequestLog{
+		URL:       requestURL.String(),
+		Method:    http.MethodPost,
+		Headers:   httpReq.Header.Clone(),
+		Body:      payload,
+		Provider:  e.Identifier(),
+		AuthID:    authID,
+		AuthLabel: authLabel,
+		AuthType:  authType,
+		AuthValue: authValue,
+	})
+
+	return httpReq, nil
+}
+
+func tokenExpiry(metadata map[string]any) time.Time {
+	if metadata == nil {
+		return time.Time{}
+	}
+	if expStr, ok := metadata["expired"].(string); ok {
+		expStr = strings.TrimSpace(expStr)
+		if expStr != "" {
+			if parsed, errParse := time.Parse(time.RFC3339, expStr); errParse == nil {
+				return parsed
+			}
+		}
+	}
+	expiresIn, hasExpires := int64Value(metadata["expires_in"])
+	tsMs, hasTimestamp := int64Value(metadata["timestamp"])
+	if hasExpires && hasTimestamp {
+		return time.Unix(0, tsMs*int64(time.Millisecond)).Add(time.Duration(expiresIn) * time.Second)
+	}
+	return time.Time{}
+}
+
+func metaStringValue(metadata map[string]any, key string) string {
+	if metadata == nil {
+		return ""
+	}
+	if v, ok := metadata[key]; ok {
+		switch typed := v.(type) {
+		case string:
+			return strings.TrimSpace(typed)
+		case []byte:
+			return strings.TrimSpace(string(typed))
+		}
+	}
+	return ""
+}
+
+func int64Value(value any) (int64, bool) {
+	switch typed := value.(type) {
+	case int:
+		return int64(typed), true
+	case int64:
+		return typed, true
+	case float64:
+		return int64(typed), true
+	case json.Number:
+		if i, errParse := typed.Int64(); errParse == nil {
+			return i, true
+		}
+	case string:
+		if strings.TrimSpace(typed) == "" {
+			return 0, false
+		}
+		if i, errParse := strconv.ParseInt(strings.TrimSpace(typed), 10, 64); errParse == nil {
+			return i, true
+		}
+	}
+	return 0, false
+}
+
+func buildBaseURL(auth *cliproxyauth.Auth) string {
+	if auth != nil {
+		if auth.Attributes != nil {
+			if v := strings.TrimSpace(auth.Attributes["base_url"]); v != "" {
+				return strings.TrimSuffix(v, "/")
+			}
+		}
+		if auth.Metadata != nil {
+			if v, ok := auth.Metadata["base_url"].(string); ok {
+				v = strings.TrimSpace(v)
+				if v != "" {
+					return strings.TrimSuffix(v, "/")
+				}
+			}
+		}
+	}
+	return antigravityBaseURL
+}
+
+func resolveHost(auth *cliproxyauth.Auth) string {
+	base := buildBaseURL(auth)
+	parsed, errParse := url.Parse(base)
+	if errParse != nil {
+		return ""
+	}
+	if parsed.Host != "" {
+		return parsed.Host
+	}
+	return strings.TrimPrefix(strings.TrimPrefix(base, "https://"), "http://")
+}
+
+func resolveUserAgent(auth *cliproxyauth.Auth) string {
+	if auth != nil {
+		if auth.Attributes != nil {
+			if ua := strings.TrimSpace(auth.Attributes["user_agent"]); ua != "" {
+				return ua
+			}
+		}
+		if auth.Metadata != nil {
+			if ua, ok := auth.Metadata["user_agent"].(string); ok && strings.TrimSpace(ua) != "" {
+				return strings.TrimSpace(ua)
+			}
+		}
+	}
+	return defaultAntigravityAgent
+}
+
+func geminiToAntigravity(modelName string, payload []byte) []byte {
+	template, _ := sjson.Set(string(payload), "model", modelName)
+	template, _ = sjson.Set(template, "userAgent", "antigravity")
+	template, _ = sjson.Set(template, "project", generateProjectID())
+	template, _ = sjson.Set(template, "requestId", generateRequestID())
+	template, _ = sjson.Set(template, "request.sessionId", generateSessionID())
+
+	template, _ = sjson.Delete(template, "request.safetySettings")
+	template, _ = sjson.Set(template, "request.toolConfig.functionCallingConfig.mode", "VALIDATED")
+
+	gjson.Get(template, "request.contents").ForEach(func(key, content gjson.Result) bool {
+		if content.Get("role").String() == "model" {
+			content.Get("parts").ForEach(func(partKey, part gjson.Result) bool {
+				if part.Get("functionCall").Exists() {
+					template, _ = sjson.Set(template, fmt.Sprintf("request.contents.%d.parts.%d.thoughtSignature", key.Int(), partKey.Int()), "skip_thought_signature_validator")
+				}
+				return true
+			})
+		}
+		return true
+	})
+
+	return []byte(template)
+}
+
+func generateRequestID() string {
+	return "agent-" + uuid.NewString()
+}
+
+func generateSessionID() string {
+	n := randSource.Int63n(9_000_000_000_000_000_000)
+	return "-" + strconv.FormatInt(n, 10)
+}
+
+func generateProjectID() string {
+	adjectives := []string{"useful", "bright", "swift", "calm", "bold"}
+	nouns := []string{"fuze", "wave", "spark", "flow", "core"}
+	adj := adjectives[randSource.Intn(len(adjectives))]
+	noun := nouns[randSource.Intn(len(nouns))]
+	randomPart := strings.ToLower(uuid.NewString())[:5]
+	return adj + "-" + noun + "-" + randomPart
+}

internal/runtime/executor/usage_helpers.go

@@ -12,6 +12,7 @@ import (
 	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
 	"github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/usage"
 	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
 )
 
 type usageReporter struct {
@@ -383,3 +384,94 @@ func jsonPayload(line []byte) []byte {
 	}
 	return trimmed
 }
+
+// FilterSSEUsageMetadata removes usageMetadata from intermediate SSE events so that
+// only the terminal chunk retains token statistics.
+// This function is shared between aistudio and antigravity executors.
+func FilterSSEUsageMetadata(payload []byte) []byte {
+	if len(payload) == 0 {
+		return payload
+	}
+
+	lines := bytes.Split(payload, []byte("\n"))
+	modified := false
+	for idx, line := range lines {
+		trimmed := bytes.TrimSpace(line)
+		if len(trimmed) == 0 || !bytes.HasPrefix(trimmed, []byte("data:")) {
+			continue
+		}
+		dataIdx := bytes.Index(line, []byte("data:"))
+		if dataIdx < 0 {
+			continue
+		}
+		rawJSON := bytes.TrimSpace(line[dataIdx+5:])
+		cleaned, changed := StripUsageMetadataFromJSON(rawJSON)
+		if !changed {
+			continue
+		}
+		var rebuilt []byte
+		rebuilt = append(rebuilt, line[:dataIdx]...)
+		rebuilt = append(rebuilt, []byte("data:")...)
+		if len(cleaned) > 0 {
+			rebuilt = append(rebuilt, ' ')
+			rebuilt = append(rebuilt, cleaned...)
+		}
+		lines[idx] = rebuilt
+		modified = true
+	}
+	if !modified {
+		return payload
+	}
+	return bytes.Join(lines, []byte("\n"))
+}
+
+// StripUsageMetadataFromJSON drops usageMetadata when no finishReason is present.
+// This function is shared between aistudio and antigravity executors.
+// It handles both formats:
+// - Aistudio: candidates.0.finishReason
+// - Antigravity: response.candidates.0.finishReason
+func StripUsageMetadataFromJSON(rawJSON []byte) ([]byte, bool) {
+	jsonBytes := bytes.TrimSpace(rawJSON)
+	if len(jsonBytes) == 0 || !gjson.ValidBytes(jsonBytes) {
+		return rawJSON, false
+	}
+
+	// Check for finishReason in both aistudio and antigravity formats
+	finishReason := gjson.GetBytes(jsonBytes, "candidates.0.finishReason")
+	if !finishReason.Exists() {
+		finishReason = gjson.GetBytes(jsonBytes, "response.candidates.0.finishReason")
+	}
+
+	// If finishReason exists and is not empty, keep the usageMetadata
+	if finishReason.Exists() && finishReason.String() != "" {
+		return rawJSON, false
+	}
+
+	// Check for usageMetadata in both possible locations
+	usageMetadata := gjson.GetBytes(jsonBytes, "usageMetadata")
+	if !usageMetadata.Exists() {
+		usageMetadata = gjson.GetBytes(jsonBytes, "response.usageMetadata")
+	}
+
+	if !usageMetadata.Exists() {
+		return rawJSON, false
+	}
+
+	// Remove usageMetadata from both possible locations
+	cleaned := jsonBytes
+	var changed bool
+
+	// Try to remove usageMetadata from root level
+	if gjson.GetBytes(cleaned, "usageMetadata").Exists() {
+		cleaned, _ = sjson.DeleteBytes(cleaned, "usageMetadata")
+		changed = true
+	}
+
+	// Try to remove usageMetadata from response level
+	if gjson.GetBytes(cleaned, "response.usageMetadata").Exists() {
+		cleaned, _ = sjson.DeleteBytes(cleaned, "response.usageMetadata")
+		changed = true
+	}
+
+	return cleaned, changed
+}

internal/translator/gemini-cli/gemini/gemini-cli_gemini_response.go

@@ -6,6 +6,7 @@
 package gemini
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 
@@ -13,7 +14,7 @@ import (
 	"github.com/tidwall/sjson"
 )
 
-// ConvertGeminiCliRequestToGemini parses and transforms a Gemini CLI API request into Gemini API format.
+// ConvertGeminiCliResponseToGemini parses and transforms a Gemini CLI API request into Gemini API format.
 // It extracts the model name, system instruction, message contents, and tool declarations
 // from the raw JSON request and returns them in the format expected by the Gemini API.
 // The function performs the following transformations:
@@ -29,7 +30,11 @@ import (
 //
 // Returns:
 //   - []string: The transformed request data in Gemini API format
-func ConvertGeminiCliRequestToGemini(ctx context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) []string {
+func ConvertGeminiCliResponseToGemini(ctx context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) []string {
+	if bytes.HasPrefix(rawJSON, []byte("data:")) {
+		rawJSON = bytes.TrimSpace(rawJSON[5:])
+	}
+
 	if alt, ok := ctx.Value("alt").(string); ok {
 		var chunk []byte
 		if alt == "" {
@@ -56,7 +61,7 @@ func ConvertGeminiCliRequestToGemini(ctx context.Context, _ string, originalRequ
 	return []string{}
 }
 
-// ConvertGeminiCliRequestToGeminiNonStream converts a non-streaming Gemini CLI request to a non-streaming Gemini response.
+// ConvertGeminiCliResponseToGeminiNonStream converts a non-streaming Gemini CLI request to a non-streaming Gemini response.
 // This function processes the complete Gemini CLI request and transforms it into a single Gemini-compatible
 // JSON response. It extracts the response data from the request and returns it in the expected format.
 //
@@ -68,7 +73,7 @@ func ConvertGeminiCliRequestToGemini(ctx context.Context, _ string, originalRequ
 //
 // Returns:
 //   - string: A Gemini-compatible JSON response containing the response data
-func ConvertGeminiCliRequestToGeminiNonStream(_ context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) string {
+func ConvertGeminiCliResponseToGeminiNonStream(_ context.Context, _ string, originalRequestRawJSON, requestRawJSON, rawJSON []byte, _ *any) string {
 	responseResult := gjson.GetBytes(rawJSON, "response")
 	if responseResult.Exists() {
 		return responseResult.Raw

internal/translator/gemini-cli/gemini/init.go

@@ -12,8 +12,8 @@ func init() {
 		GeminiCLI,
 		ConvertGeminiRequestToGeminiCLI,
 		interfaces.TranslateResponse{
-			Stream:     ConvertGeminiCliRequestToGemini,
-			NonStream:  ConvertGeminiCliRequestToGeminiNonStream,
+			Stream:     ConvertGeminiCliResponseToGemini,
+			NonStream:  ConvertGeminiCliResponseToGeminiNonStream,
 			TokenCount: GeminiTokenCount,
 		},
 	)

internal/translator/gemini-cli/openai/chat-completions/gemini-cli_openai_response.go

@@ -98,25 +98,40 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 	// Process the main content part of the response.
 	partsResult := gjson.GetBytes(rawJSON, "response.candidates.0.content.parts")
 	hasFunctionCall := false
+	hasValidContent := false
 	if partsResult.IsArray() {
 		partResults := partsResult.Array()
 		for i := 0; i < len(partResults); i++ {
 			partResult := partResults[i]
 			partTextResult := partResult.Get("text")
 			functionCallResult := partResult.Get("functionCall")
+			thoughtSignatureResult := partResult.Get("thoughtSignature")
 			inlineDataResult := partResult.Get("inlineData")
 			if !inlineDataResult.Exists() {
 				inlineDataResult = partResult.Get("inline_data")
 			}
 
+			// Handle thoughtSignature - this is encrypted reasoning content that should not be exposed to the client
+			if thoughtSignatureResult.Exists() && thoughtSignatureResult.String() != "" {
+				// Skip thoughtSignature processing - it's internal encrypted data
+				continue
+			}
+
 			if partTextResult.Exists() {
+				textContent := partTextResult.String()
+				// Skip empty text content to avoid generating unnecessary chunks
+				if textContent == "" {
+					continue
+				}
+
 				// Handle text content, distinguishing between regular content and reasoning/thoughts.
 				if partResult.Get("thought").Bool() {
-					template, _ = sjson.Set(template, "choices.0.delta.reasoning_content", partTextResult.String())
+					template, _ = sjson.Set(template, "choices.0.delta.reasoning_content", textContent)
 				} else {
-					template, _ = sjson.Set(template, "choices.0.delta.content", partTextResult.String())
+					template, _ = sjson.Set(template, "choices.0.delta.content", textContent)
 				}
 				template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
+				hasValidContent = true
 			} else if functionCallResult.Exists() {
 				// Handle function call content.
 				hasFunctionCall = true
@@ -176,6 +191,12 @@ func ConvertCliResponseToOpenAI(_ context.Context, _ string, originalRequestRawJ
 		template, _ = sjson.Set(template, "choices.0.native_finish_reason", "tool_calls")
 	}
 
+	// Only return a chunk if there's actual content or a finish reason
+	finishReason := gjson.GetBytes(rawJSON, "response.candidates.0.finishReason")
+	if !hasValidContent && !finishReason.Exists() {
+		return []string{}
+	}
+
 	return []string{template}
 }
 

internal/util/gemini_thinking.go

@@ -5,6 +5,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
 )
 
@@ -212,3 +213,49 @@ func StripThinkingConfigIfUnsupported(model string, body []byte) []byte {
 	updated, _ = sjson.DeleteBytes(updated, "generationConfig.thinkingConfig")
 	return updated
 }
+
+// ConvertThinkingLevelToBudget checks for "generationConfig.thinkingConfig.thinkingLevel"
+// and converts it to "thinkingBudget".
+// "high" -> 32768
+// "low" -> 128
+// It removes "thinkingLevel" after conversion.
+func ConvertThinkingLevelToBudget(body []byte) []byte {
+	levelPath := "generationConfig.thinkingConfig.thinkingLevel"
+	res := gjson.GetBytes(body, levelPath)
+	if !res.Exists() {
+		return body
+	}
+
+	level := strings.ToLower(res.String())
+	var budget int
+	switch level {
+	case "high":
+		budget = 32768
+	case "low":
+		budget = 128
+	default:
+		// If unknown level, we might just leave it or default.
+		// User only specified high and low. We'll assume we shouldn't touch it if it's something else,
+		// or maybe we should just remove the invalid level?
+		// For safety adhering to strict instructions: "If high... if low...".
+		// If it's something else, the upstream might fail anyway if we leave it,
+		// but let's just delete the level if we processed it.
+		// Actually, let's check if we need to do anything for other values.
+		// For now, only handle high/low.
+		return body
+	}
+
+	// Set budget
+	budgetPath := "generationConfig.thinkingConfig.thinkingBudget"
+	updated, err := sjson.SetBytes(body, budgetPath, budget)
+	if err != nil {
+		return body
+	}
+
+	// Remove level
+	updated, err = sjson.DeleteBytes(updated, levelPath)
+	if err != nil {
+		return body
+	}
+	return updated
+}

sdk/auth/antigravity.go

@@ -0,0 +1,293 @@
+package auth
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/browser"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/misc"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
+	coreauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	antigravityClientID     = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
+	antigravityClientSecret = "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"
+	antigravityCallbackPort = 51121
+)
+
+var antigravityScopes = []string{
+	"https://www.googleapis.com/auth/cloud-platform",
+	"https://www.googleapis.com/auth/userinfo.email",
+	"https://www.googleapis.com/auth/userinfo.profile",
+	"https://www.googleapis.com/auth/cclog",
+	"https://www.googleapis.com/auth/experimentsandconfigs",
+}
+
+// AntigravityAuthenticator implements OAuth login for the antigravity provider.
+type AntigravityAuthenticator struct{}
+
+// NewAntigravityAuthenticator constructs a new authenticator instance.
+func NewAntigravityAuthenticator() Authenticator { return &AntigravityAuthenticator{} }
+
+// Provider returns the provider key for antigravity.
+func (AntigravityAuthenticator) Provider() string { return "antigravity" }
+
+// RefreshLead instructs the manager to refresh five minutes before expiry.
+func (AntigravityAuthenticator) RefreshLead() *time.Duration {
+	lead := 5 * time.Minute
+	return &lead
+}
+
+// Login launches a local OAuth flow to obtain antigravity tokens and persists them.
+func (AntigravityAuthenticator) Login(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {
+	if cfg == nil {
+		return nil, fmt.Errorf("cliproxy auth: configuration is required")
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if opts == nil {
+		opts = &LoginOptions{}
+	}
+
+	httpClient := util.SetProxy(&cfg.SDKConfig, &http.Client{})
+
+	state, err := misc.GenerateRandomState()
+	if err != nil {
+		return nil, fmt.Errorf("antigravity: failed to generate state: %w", err)
+	}
+
+	srv, port, cbChan, errServer := startAntigravityCallbackServer()
+	if errServer != nil {
+		return nil, fmt.Errorf("antigravity: failed to start callback server: %w", errServer)
+	}
+	defer func() {
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		defer cancel()
+		_ = srv.Shutdown(shutdownCtx)
+	}()
+
+	redirectURI := fmt.Sprintf("http://localhost:%d/oauth-callback", port)
+	authURL := buildAntigravityAuthURL(redirectURI, state)
+
+	if !opts.NoBrowser {
+		fmt.Println("Opening browser for antigravity authentication")
+		if !browser.IsAvailable() {
+			log.Warn("No browser available; please open the URL manually")
+			util.PrintSSHTunnelInstructions(port)
+			fmt.Printf("Visit the following URL to continue authentication:\n%s\n", authURL)
+		} else if errOpen := browser.OpenURL(authURL); errOpen != nil {
+			log.Warnf("Failed to open browser automatically: %v", errOpen)
+			util.PrintSSHTunnelInstructions(port)
+			fmt.Printf("Visit the following URL to continue authentication:\n%s\n", authURL)
+		}
+	} else {
+		util.PrintSSHTunnelInstructions(port)
+		fmt.Printf("Visit the following URL to continue authentication:\n%s\n", authURL)
+	}
+
+	fmt.Println("Waiting for antigravity authentication callback...")
+
+	var cbRes callbackResult
+	select {
+	case res := <-cbChan:
+		cbRes = res
+	case <-time.After(5 * time.Minute):
+		return nil, fmt.Errorf("antigravity: authentication timed out")
+	}
+
+	if cbRes.Error != "" {
+		return nil, fmt.Errorf("antigravity: authentication failed: %s", cbRes.Error)
+	}
+	if cbRes.State != state {
+		return nil, fmt.Errorf("antigravity: invalid state")
+	}
+	if cbRes.Code == "" {
+		return nil, fmt.Errorf("antigravity: missing authorization code")
+	}
+
+	tokenResp, errToken := exchangeAntigravityCode(ctx, cbRes.Code, redirectURI, httpClient)
+	if errToken != nil {
+		return nil, fmt.Errorf("antigravity: token exchange failed: %w", errToken)
+	}
+
+	email := ""
+	if tokenResp.AccessToken != "" {
+		if info, errInfo := fetchAntigravityUserInfo(ctx, tokenResp.AccessToken, httpClient); errInfo == nil && strings.TrimSpace(info.Email) != "" {
+			email = strings.TrimSpace(info.Email)
+		}
+	}
+
+	now := time.Now()
+	metadata := map[string]any{
+		"type":          "antigravity",
+		"access_token":  tokenResp.AccessToken,
+		"refresh_token": tokenResp.RefreshToken,
+		"expires_in":    tokenResp.ExpiresIn,
+		"timestamp":     now.UnixMilli(),
+		"expired":       now.Add(time.Duration(tokenResp.ExpiresIn) * time.Second).Format(time.RFC3339),
+	}
+	if email != "" {
+		metadata["email"] = email
+	}
+
+	fileName := sanitizeAntigravityFileName(email)
+	label := email
+	if label == "" {
+		label = "antigravity"
+	}
+
+	fmt.Println("Antigravity authentication successful")
+	return &coreauth.Auth{
+		ID:       fileName,
+		Provider: "antigravity",
+		FileName: fileName,
+		Label:    label,
+		Metadata: metadata,
+	}, nil
+}
+
+type callbackResult struct {
+	Code  string
+	Error string
+	State string
+}
+
+func startAntigravityCallbackServer() (*http.Server, int, <-chan callbackResult, error) {
+	addr := fmt.Sprintf(":%d", antigravityCallbackPort)
+	listener, err := net.Listen("tcp", addr)
+	if err != nil {
+		return nil, 0, nil, err
+	}
+	port := listener.Addr().(*net.TCPAddr).Port
+	resultCh := make(chan callbackResult, 1)
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/oauth-callback", func(w http.ResponseWriter, r *http.Request) {
+		q := r.URL.Query()
+		res := callbackResult{
+			Code:  strings.TrimSpace(q.Get("code")),
+			Error: strings.TrimSpace(q.Get("error")),
+			State: strings.TrimSpace(q.Get("state")),
+		}
+		resultCh <- res
+		if res.Code != "" && res.Error == "" {
+			_, _ = w.Write([]byte("<h1>Login successful</h1><p>You can close this window.</p>"))
+		} else {
+			_, _ = w.Write([]byte("<h1>Login failed</h1><p>Please check the CLI output.</p>"))
+		}
+	})
+
+	srv := &http.Server{Handler: mux}
+	go func() {
+		if errServe := srv.Serve(listener); errServe != nil && !strings.Contains(errServe.Error(), "Server closed") {
+			log.Warnf("antigravity callback server error: %v", errServe)
+		}
+	}()
+
+	return srv, port, resultCh, nil
+}
+
+type antigravityTokenResponse struct {
+	AccessToken  string `json:"access_token"`
+	RefreshToken string `json:"refresh_token"`
+	ExpiresIn    int64  `json:"expires_in"`
+	TokenType    string `json:"token_type"`
+}
+
+func exchangeAntigravityCode(ctx context.Context, code, redirectURI string, httpClient *http.Client) (*antigravityTokenResponse, error) {
+	data := url.Values{}
+	data.Set("code", code)
+	data.Set("client_id", antigravityClientID)
+	data.Set("client_secret", antigravityClientSecret)
+	data.Set("redirect_uri", redirectURI)
+	data.Set("grant_type", "authorization_code")
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://oauth2.googleapis.com/token", strings.NewReader(data.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	resp, errDo := httpClient.Do(req)
+	if errDo != nil {
+		return nil, errDo
+	}
+	defer func() {
+		if errClose := resp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity token exchange: close body error: %v", errClose)
+		}
+	}()
+
+	var token antigravityTokenResponse
+	if errDecode := json.NewDecoder(resp.Body).Decode(&token); errDecode != nil {
+		return nil, errDecode
+	}
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+		return nil, fmt.Errorf("oauth token exchange failed: status %d", resp.StatusCode)
+	}
+	return &token, nil
+}
+
+type antigravityUserInfo struct {
+	Email string `json:"email"`
+}
+
+func fetchAntigravityUserInfo(ctx context.Context, accessToken string, httpClient *http.Client) (*antigravityUserInfo, error) {
+	if strings.TrimSpace(accessToken) == "" {
+		return &antigravityUserInfo{}, nil
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://www.googleapis.com/oauth2/v1/userinfo?alt=json", nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+
+	resp, errDo := httpClient.Do(req)
+	if errDo != nil {
+		return nil, errDo
+	}
+	defer func() {
+		if errClose := resp.Body.Close(); errClose != nil {
+			log.Errorf("antigravity userinfo: close body error: %v", errClose)
+		}
+	}()
+
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+		return &antigravityUserInfo{}, nil
+	}
+	var info antigravityUserInfo
+	if errDecode := json.NewDecoder(resp.Body).Decode(&info); errDecode != nil {
+		return nil, errDecode
+	}
+	return &info, nil
+}
+
+func buildAntigravityAuthURL(redirectURI, state string) string {
+	params := url.Values{}
+	params.Set("access_type", "offline")
+	params.Set("client_id", antigravityClientID)
+	params.Set("prompt", "consent")
+	params.Set("redirect_uri", redirectURI)
+	params.Set("response_type", "code")
+	params.Set("scope", strings.Join(antigravityScopes, " "))
+	params.Set("state", state)
+	return "https://accounts.google.com/o/oauth2/v2/auth?" + params.Encode()
+}
+
+func sanitizeAntigravityFileName(email string) string {
+	if strings.TrimSpace(email) == "" {
+		return "antigravity.json"
+	}
+	replacer := strings.NewReplacer("@", "_", ".", "_")
+	return fmt.Sprintf("antigravity-%s.json", replacer.Replace(email))
+}

sdk/auth/refresh_registry.go

@@ -13,6 +13,7 @@ func init() {
 	registerRefreshLead("iflow", func() Authenticator { return NewIFlowAuthenticator() })
 	registerRefreshLead("gemini", func() Authenticator { return NewGeminiAuthenticator() })
 	registerRefreshLead("gemini-cli", func() Authenticator { return NewGeminiAuthenticator() })
+	registerRefreshLead("antigravity", func() Authenticator { return NewAntigravityAuthenticator() })
 }
 
 func registerRefreshLead(provider string, factory func() Authenticator) {

sdk/cliproxy/service.go

@@ -333,6 +333,8 @@ func (s *Service) ensureExecutorsForAuth(a *coreauth.Auth) {
 			s.coreManager.RegisterExecutor(executor.NewAIStudioExecutor(s.cfg, a.ID, s.wsGateway))
 		}
 		return
+	case "antigravity":
+		s.coreManager.RegisterExecutor(executor.NewAntigravityExecutor(s.cfg))
 	case "claude":
 		s.coreManager.RegisterExecutor(executor.NewClaudeExecutor(s.cfg))
 	case "codex":
@@ -634,6 +636,10 @@ func (s *Service) registerModelsForAuth(a *coreauth.Auth) {
 		models = registry.GetGeminiCLIModels()
 	case "aistudio":
 		models = registry.GetAIStudioModels()
+	case "antigravity":
+		ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+		models = executor.FetchAntigravityModels(ctx, a, s.cfg)
+		cancel()
 	case "claude":
 		models = registry.GetClaudeModels()
 		if entry := s.resolveConfigClaudeKey(a); entry != nil && len(entry.Models) > 0 {

sdk/translator/formats.go

@@ -8,4 +8,5 @@ const (
 	FormatGemini         Format = "gemini"
 	FormatGeminiCLI      Format = "gemini-cli"
 	FormatCodex          Format = "codex"
+	FormatAntigravity    Format = "antigravity"
 )