diff --git a/.gitignore b/.gitignore
index 3a3c871b..9824a36d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,6 +41,7 @@ GEMINI.md
 .gemini/*
 .serena/*
 .agent/*
+.agents
 .agents/*
 .opencode/*
 .idea/*
diff --git a/internal/registry/model_definitions.go b/internal/registry/model_definitions.go
index 22fd15f3..320ffc54 100644
--- a/internal/registry/model_definitions.go
+++ b/internal/registry/model_definitions.go
@@ -85,6 +85,31 @@ func GetAntigravityModels() []*ModelInfo {
 	return cloneModelInfos(getModels().Antigravity)
 }
 
+// AntigravityWebSearchModelFor returns the Antigravity model that should run a
+// native web search request for modelID.
+func AntigravityWebSearchModelFor(modelID string) string {
+	modelID = normalizeAntigravityCapabilityModelID(modelID)
+	if modelID == "" {
+		return ""
+	}
+	for _, model := range GetGlobalRegistry().GetAvailableModelsByProvider("antigravity") {
+		if model == nil {
+			continue
+		}
+		currentModelID := normalizeAntigravityCapabilityModelID(model.ID)
+		if currentModelID == "" {
+			continue
+		}
+		if currentModelID == modelID {
+			if model.SupportsWebSearch {
+				return currentModelID
+			}
+			return ""
+		}
+	}
+	return ""
+}
+
 // GetXAIModels returns the standard xAI Grok model definitions.
 func GetXAIModels() []*ModelInfo {
 	return WithXAIBuiltins(cloneModelInfos(getModels().XAI))
@@ -103,6 +128,14 @@ func WithXAIBuiltins(models []*ModelInfo) []*ModelInfo {
 	return upsertModelInfos(models, xaiBuiltinImageModelInfo(), xaiBuiltinImageQualityModelInfo(), xaiBuiltinVideoModelInfo(), xaiBuiltinVideo15PreviewModelInfo())
 }
 
+func normalizeAntigravityCapabilityModelID(modelID string) string {
+	modelID = strings.ToLower(strings.TrimSpace(modelID))
+	if open := strings.LastIndex(modelID, "("); open >= 0 && strings.HasSuffix(modelID, ")") {
+		modelID = strings.TrimSpace(modelID[:open])
+	}
+	return modelID
+}
+
 func codexBuiltinImageModelInfo() *ModelInfo {
 	return &ModelInfo{
 		ID:          codexBuiltinImageModelID,
diff --git a/internal/registry/model_definitions_test.go b/internal/registry/model_definitions_test.go
index 15e2a167..86569687 100644
--- a/internal/registry/model_definitions_test.go
+++ b/internal/registry/model_definitions_test.go
@@ -16,3 +16,35 @@ func TestWithXAIBuiltinsIncludesVideoPreviewModel(t *testing.T) {
 
 	t.Fatalf("expected xAI builtin model %s", xaiBuiltinVideo15PreviewModelID)
 }
+
+func TestAntigravityWebSearchModelForRequiresRequestedModelCapability(t *testing.T) {
+	registryRef := GetGlobalRegistry()
+	registryRef.RegisterClient("test-antigravity-websearch-route", "antigravity", []*ModelInfo{
+		{ID: "gemini-route-test"},
+		{ID: "gemini-web-search-test", SupportsWebSearch: true},
+	})
+	registryRef.RegisterClient("test-gemini-websearch-route", "gemini", []*ModelInfo{
+		{ID: "gemini-cross-provider-route"},
+		{ID: "gemini-cross-provider-search", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() {
+		registryRef.UnregisterClient("test-antigravity-websearch-route")
+		registryRef.UnregisterClient("test-gemini-websearch-route")
+	})
+
+	if got := AntigravityWebSearchModelFor("gemini-route-test"); got != "" {
+		t.Fatalf("route model without web search support should not get fallback model, got %q", got)
+	}
+	if got := AntigravityWebSearchModelFor("gemini-route-test(high)"); got != "" {
+		t.Fatalf("suffix route model without web search support should not get fallback model, got %q", got)
+	}
+	if got := AntigravityWebSearchModelFor("gemini-web-search-test"); got != "gemini-web-search-test" {
+		t.Fatalf("AntigravityWebSearchModelFor capable model = %q, want itself", got)
+	}
+	if got := AntigravityWebSearchModelFor("gemini-cross-provider-route"); got != "" {
+		t.Fatalf("cross-provider model should not get Antigravity web search model, got %q", got)
+	}
+	if got := AntigravityWebSearchModelFor("unknown-model"); got != "" {
+		t.Fatalf("unknown model should not get Antigravity web search model, got %q", got)
+	}
+}
diff --git a/internal/registry/model_registry.go b/internal/registry/model_registry.go
index afa3918b..3fab95e3 100644
--- a/internal/registry/model_registry.go
+++ b/internal/registry/model_registry.go
@@ -54,6 +54,9 @@ type ModelInfo struct {
 	SupportedInputModalities []string `json:"supportedInputModalities,omitempty"`
 	// SupportedOutputModalities lists supported output modalities (e.g., TEXT, IMAGE)
 	SupportedOutputModalities []string `json:"supportedOutputModalities,omitempty"`
+	// SupportsWebSearch indicates this Antigravity model is listed by
+	// fetchAvailableModels.webSearchModelIds and can execute native googleSearch.
+	SupportsWebSearch bool `json:"supports_web_search,omitempty"`
 
 	// Thinking holds provider-specific reasoning/thinking budget capabilities.
 	// This is optional and currently used for Gemini thinking budget normalization.
diff --git a/internal/runtime/executor/antigravity_executor.go b/internal/runtime/executor/antigravity_executor.go
index 2889ca14..cd3b191c 100644
--- a/internal/runtime/executor/antigravity_executor.go
+++ b/internal/runtime/executor/antigravity_executor.go
@@ -271,6 +271,46 @@ func validateAntigravityRequestSignatures(from sdktranslator.Format, rawJSON []b
 	return rawJSON, nil
 }
 
+func hasAntigravityClaudeTypedWebSearchTool(payload []byte) bool {
+	tools := gjson.GetBytes(payload, "tools")
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		switch tool.Get("type").String() {
+		case "web_search_20250305", "web_search_20260209":
+			return true
+		}
+	}
+	return false
+}
+
+func hasAntigravityGoogleSearchTool(payload []byte) bool {
+	tools := gjson.GetBytes(payload, "request.tools")
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		if tool.Get("googleSearch").Exists() {
+			return true
+		}
+	}
+	return false
+}
+
+func shouldResolveAntigravityWebSearchGroundingURLs(from sdktranslator.Format, originalRequestRawJSON, requestRawJSON []byte) bool {
+	return from.String() == "claude" &&
+		hasAntigravityClaudeTypedWebSearchTool(originalRequestRawJSON) &&
+		hasAntigravityGoogleSearchTool(requestRawJSON)
+}
+
+func (e *AntigravityExecutor) resolveWebSearchGroundingURLs(ctx context.Context, auth *cliproxyauth.Auth, from sdktranslator.Format, originalRequestRawJSON, requestRawJSON, responseRawJSON []byte) []byte {
+	if !shouldResolveAntigravityWebSearchGroundingURLs(from, originalRequestRawJSON, requestRawJSON) {
+		return responseRawJSON
+	}
+	return helps.ResolveAntigravityGroundingURLs(ctx, e.cfg, auth, responseRawJSON)
+}
+
 func countClaudeThinkingBlocks(rawJSON []byte) int {
 	messages := gjson.GetBytes(rawJSON, "messages")
 	if !messages.IsArray() {
@@ -709,6 +749,7 @@ attemptLoop:
 			if useCredits {
 				clearAntigravityCreditsFailureState(auth)
 			}
+			bodyBytes = e.resolveWebSearchGroundingURLs(ctx, auth, from, originalPayload, translated, bodyBytes)
 			reporter.Publish(ctx, helps.ParseAntigravityUsage(bodyBytes))
 			var param any
 			converted := sdktranslator.TranslateNonStream(ctx, to, responseFormat, req.Model, opts.OriginalRequest, translated, bodyBytes, &param)
@@ -973,6 +1014,7 @@ attemptLoop:
 			}
 			resp = cliproxyexecutor.Response{Payload: e.convertStreamToNonStream(buffer.Bytes())}
 
+			resp.Payload = e.resolveWebSearchGroundingURLs(ctx, auth, from, originalPayload, translated, resp.Payload)
 			reporter.Publish(ctx, helps.ParseAntigravityUsage(resp.Payload))
 			var param any
 			converted := sdktranslator.TranslateNonStream(ctx, to, responseFormat, req.Model, opts.OriginalRequest, translated, resp.Payload, &param)
@@ -1414,6 +1456,7 @@ attemptLoop:
 						reporter.Publish(ctx, detail)
 					}
 
+					payload = e.resolveWebSearchGroundingURLs(ctx, auth, from, originalPayload, translated, payload)
 					chunks := sdktranslator.TranslateStream(ctx, to, responseFormat, req.Model, opts.OriginalRequest, translated, bytes.Clone(payload), &param)
 					for i := range chunks {
 						select {
@@ -2473,14 +2516,15 @@ func geminiToAntigravity(modelName string, payload []byte, projectID string) []b
 	template, _ = sjson.SetBytes(template, "userAgent", "antigravity")
 
 	isImageModel := strings.Contains(modelName, "image")
-
-	var reqType string
-	if isImageModel {
-		reqType = "image_gen"
-	} else {
-		reqType = "agent"
+	reqType := strings.TrimSpace(gjson.GetBytes(template, "requestType").String())
+	if reqType == "" {
+		if isImageModel {
+			reqType = "image_gen"
+		} else {
+			reqType = "agent"
+		}
+		template, _ = sjson.SetBytes(template, "requestType", reqType)
 	}
-	template, _ = sjson.SetBytes(template, "requestType", reqType)
 
 	if projectID != "" {
 		template, _ = sjson.SetBytes(template, "project", projectID)
@@ -2490,7 +2534,7 @@ func geminiToAntigravity(modelName string, payload []byte, projectID string) []b
 
 	if isImageModel {
 		template, _ = sjson.SetBytes(template, "requestId", generateImageGenRequestID())
-	} else {
+	} else if reqType != "web_search" {
 		template, _ = sjson.SetBytes(template, "requestId", generateRequestID())
 		template, _ = sjson.SetBytes(template, "request.sessionId", generateStableSessionID(payload))
 	}
diff --git a/internal/runtime/executor/antigravity_executor_buildrequest_test.go b/internal/runtime/executor/antigravity_executor_buildrequest_test.go
index e47a500b..ff4f69f1 100644
--- a/internal/runtime/executor/antigravity_executor_buildrequest_test.go
+++ b/internal/runtime/executor/antigravity_executor_buildrequest_test.go
@@ -10,6 +10,7 @@ import (
 	"time"
 
 	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v7/sdk/cliproxy/auth"
+	sdktranslator "github.com/router-for-me/CLIProxyAPI/v7/sdk/translator"
 )
 
 func TestAntigravityBuildRequest_SanitizesGeminiToolSchema(t *testing.T) {
@@ -110,6 +111,86 @@ func TestAntigravityBuildRequest_UsesAuthProjectID(t *testing.T) {
 	}
 }
 
+func TestAntigravityBuildRequest_UsesRouteModelWhenPayloadContainsDifferentModel(t *testing.T) {
+	body := buildRequestBodyFromRawPayload(t, "gemini-3-flash-agent", []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"request": {
+			"contents": [
+				{
+					"role": "user",
+					"parts": [{"text": "Perform a web search"}]
+				}
+			],
+			"tools": [{"googleSearch": {}}]
+		}
+	}`))
+
+	if got, ok := body["model"].(string); !ok || got != "gemini-3-flash-agent" {
+		t.Fatalf("request model should stay on route model, got=%v", body["model"])
+	}
+}
+
+func TestAntigravityBuildRequest_PreservesIndependentWebSearchRequestType(t *testing.T) {
+	body := buildRequestBodyFromRawPayload(t, "gemini-3.1-flash-lite", []byte(`{
+		"requestType": "web_search",
+		"request": {
+			"contents": [
+				{
+					"role": "user",
+					"parts": [{"text": "北京天气 2026-06-12"}]
+				}
+			],
+			"tools": [
+				{
+					"googleSearch": {
+						"enhancedContent": {
+							"imageSearch": {
+								"maxResultCount": 5
+							}
+						}
+					}
+				}
+			],
+			"generationConfig": {
+				"candidateCount": 1
+			}
+		}
+	}`))
+
+	if got, ok := body["requestType"].(string); !ok || got != "web_search" {
+		t.Fatalf("requestType should stay web_search, got=%v", body["requestType"])
+	}
+	if _, ok := body["requestId"]; ok {
+		t.Fatalf("web_search request should not add requestId: %v", body["requestId"])
+	}
+	request, ok := body["request"].(map[string]any)
+	if !ok {
+		t.Fatalf("request missing or invalid: %v", body["request"])
+	}
+	if _, ok := request["sessionId"]; ok {
+		t.Fatalf("web_search request should not add request.sessionId: %v", request["sessionId"])
+	}
+	if got, ok := body["project"].(string); !ok || got != "project-1" {
+		t.Fatalf("project should come from auth metadata, got=%v", body["project"])
+	}
+}
+
+func TestShouldResolveAntigravityWebSearchGroundingURLsRequiresTypedWebSearchAndSearchRequest(t *testing.T) {
+	original := []byte(`{"tools":[{"type":"web_search_20250305","name":"web_search"}]}`)
+	translatedWithGoogleSearch := []byte(`{"requestType":"web_search","request":{"tools":[{"googleSearch":{}}]}}`)
+	translatedWithoutGoogleSearch := []byte(`{"request":{"contents":[]}}`)
+
+	if !shouldResolveAntigravityWebSearchGroundingURLs(sdktranslator.FormatClaude, original, translatedWithGoogleSearch) {
+		t.Fatal("expected typed Claude web search translated to web_search request to resolve grounding URLs")
+	}
+	if shouldResolveAntigravityWebSearchGroundingURLs(sdktranslator.FormatClaude, original, translatedWithoutGoogleSearch) {
+		t.Fatal("expected request without googleSearch to skip grounding URL resolution")
+	}
+	if shouldResolveAntigravityWebSearchGroundingURLs(sdktranslator.FormatOpenAI, original, translatedWithGoogleSearch) {
+		t.Fatal("expected non-Claude source format to skip grounding URL resolution")
+	}
+}
+
 func TestAntigravityPrepareRequestAuth_FetchesMissingProjectID(t *testing.T) {
 	executor := &AntigravityExecutor{}
 	auth := &cliproxyauth.Auth{Metadata: map[string]any{
diff --git a/internal/runtime/executor/helps/antigravity_grounding_urls.go b/internal/runtime/executor/helps/antigravity_grounding_urls.go
new file mode 100644
index 00000000..1c4233d2
--- /dev/null
+++ b/internal/runtime/executor/helps/antigravity_grounding_urls.go
@@ -0,0 +1,104 @@
+package helps
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/config"
+	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v7/sdk/cliproxy/auth"
+	log "github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+func isAntigravityVertexSearchRedirect(rawURL string) bool {
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		return false
+	}
+	return parsed.Scheme == "https" &&
+		parsed.Host == "vertexaisearch.cloud.google.com" &&
+		strings.HasPrefix(parsed.Path, "/grounding-api-redirect/")
+}
+
+func resolveAntigravityGroundingURL(ctx context.Context, cfg *config.Config, auth *cliproxyauth.Auth, rawURL string) string {
+	if !isAntigravityVertexSearchRedirect(rawURL) {
+		return rawURL
+	}
+	client := NewProxyAwareHTTPClient(ctx, cfg, auth, 0)
+	client.CheckRedirect = func(_ *http.Request, _ []*http.Request) error {
+		return http.ErrUseLastResponse
+	}
+	req, errReq := http.NewRequestWithContext(ctx, http.MethodHead, rawURL, nil)
+	if errReq != nil {
+		log.WithError(errReq).Debug("antigravity grounding url: create redirect request failed")
+		return rawURL
+	}
+	resp, errDo := client.Do(req)
+	if errDo != nil {
+		log.WithError(errDo).Debug("antigravity grounding url: resolve redirect failed")
+		return rawURL
+	}
+	defer func() {
+		if errClose := resp.Body.Close(); errClose != nil {
+			log.WithError(errClose).Debug("antigravity grounding url: close redirect response failed")
+		}
+	}()
+
+	if resp.StatusCode < http.StatusMultipleChoices || resp.StatusCode >= http.StatusBadRequest {
+		return rawURL
+	}
+	location := strings.TrimSpace(resp.Header.Get("Location"))
+	if location == "" {
+		return rawURL
+	}
+	parsed, errParse := url.Parse(location)
+	if errParse != nil || parsed.Scheme != "https" || parsed.Host == "" {
+		return rawURL
+	}
+	return location
+}
+
+// ResolveAntigravityGroundingURLs replaces Vertex Search redirect URLs in grounding chunks with their target URLs.
+func ResolveAntigravityGroundingURLs(ctx context.Context, cfg *config.Config, auth *cliproxyauth.Auth, payload []byte) []byte {
+	if len(payload) == 0 {
+		return payload
+	}
+
+	basePath := "response.candidates.0.groundingMetadata.groundingChunks"
+	chunks := gjson.GetBytes(payload, basePath)
+	if !chunks.IsArray() {
+		basePath = "candidates.0.groundingMetadata.groundingChunks"
+		chunks = gjson.GetBytes(payload, basePath)
+	}
+	if !chunks.IsArray() {
+		return payload
+	}
+
+	output := payload
+	resolved := map[string]string{}
+	for i, chunk := range chunks.Array() {
+		uri := strings.TrimSpace(chunk.Get("web.uri").String())
+		if uri == "" {
+			continue
+		}
+		resolvedURI, ok := resolved[uri]
+		if !ok {
+			resolvedURI = resolveAntigravityGroundingURL(ctx, cfg, auth, uri)
+			resolved[uri] = resolvedURI
+		}
+		if resolvedURI == uri {
+			continue
+		}
+		updated, errSet := sjson.SetBytes(output, fmt.Sprintf("%s.%d.web.uri", basePath, i), resolvedURI)
+		if errSet != nil {
+			log.WithError(errSet).Debug("antigravity grounding url: set resolved url failed")
+			continue
+		}
+		output = updated
+	}
+	return output
+}
diff --git a/internal/runtime/executor/helps/antigravity_grounding_urls_test.go b/internal/runtime/executor/helps/antigravity_grounding_urls_test.go
new file mode 100644
index 00000000..d3086a51
--- /dev/null
+++ b/internal/runtime/executor/helps/antigravity_grounding_urls_test.go
@@ -0,0 +1,66 @@
+package helps
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/tidwall/gjson"
+)
+
+type groundingURLRoundTripper func(*http.Request) (*http.Response, error)
+
+func (f groundingURLRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return f(req)
+}
+
+func TestResolveAntigravityGroundingURLsResolvesVertexRedirects(t *testing.T) {
+	t.Parallel()
+
+	const redirectURL = "https://vertexaisearch.cloud.google.com/grounding-api-redirect/example-token"
+	const resolvedURL = "https://example.com/weather"
+
+	var sawRedirectRequest bool
+	ctx := context.WithValue(context.Background(), "cliproxy.roundtripper", groundingURLRoundTripper(func(req *http.Request) (*http.Response, error) {
+		if req.Method != http.MethodHead {
+			t.Fatalf("method = %s, want HEAD", req.Method)
+		}
+		if req.URL.String() != redirectURL {
+			t.Fatalf("url = %s, want %s", req.URL.String(), redirectURL)
+		}
+		sawRedirectRequest = true
+		return &http.Response{
+			StatusCode: http.StatusFound,
+			Header: http.Header{
+				"Location": []string{resolvedURL},
+			},
+			Body: io.NopCloser(strings.NewReader("")),
+		}, nil
+	}))
+
+	input := []byte(`{
+		"response": {
+			"candidates": [{
+				"groundingMetadata": {
+					"groundingChunks": [
+						{"web": {"uri": "` + redirectURL + `", "title": "Weather"}},
+						{"web": {"uri": "https://already.example/source", "title": "Existing"}}
+					]
+				}
+			}]
+		}
+	}`)
+
+	output := ResolveAntigravityGroundingURLs(ctx, nil, nil, input)
+	if !sawRedirectRequest {
+		t.Fatal("expected resolver to request the vertex redirect")
+	}
+	if got := gjson.GetBytes(output, "response.candidates.0.groundingMetadata.groundingChunks.0.web.uri").String(); got != resolvedURL {
+		t.Fatalf("resolved uri = %q, want %q; output=%s", got, resolvedURL, output)
+	}
+	if got := gjson.GetBytes(output, "response.candidates.0.groundingMetadata.groundingChunks.1.web.uri").String(); got != "https://already.example/source" {
+		t.Fatalf("non-vertex uri = %q", got)
+	}
+}
diff --git a/internal/translator/antigravity/claude/antigravity_claude_request.go b/internal/translator/antigravity/claude/antigravity_claude_request.go
index 76bad5d6..d4490bc3 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_request.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_request.go
@@ -256,6 +256,9 @@ func logDroppedAntigravityToolUseSignature(modelName string, messageIndex, conte
 func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _ bool) []byte {
 	enableThoughtTranslate := true
 	rawJSON := inputRawJSON
+	if shouldBuildAntigravityWebSearchRequest(modelName, rawJSON) {
+		return buildAntigravityWebSearchRequest(modelName, rawJSON)
+	}
 
 	// system instruction
 	var systemInstructionJSON []byte
@@ -595,10 +598,13 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 	allowedToolKeys := []string{"name", "description", "behavior", "parameters", "parametersJsonSchema", "response", "responseJsonSchema"}
 	toolsResult := gjson.GetBytes(rawJSON, "tools")
 	if toolsResult.IsArray() {
-		toolsJSON = []byte(`[{"functionDeclarations":[]}]`)
+		functionToolNode := []byte(`{"functionDeclarations":[]}`)
 		toolsResults := toolsResult.Array()
 		for i := 0; i < len(toolsResults); i++ {
 			toolResult := toolsResults[i]
+			if isClaudeTypedWebSearchToolType(toolResult.Get("type").String()) {
+				continue
+			}
 			inputSchemaResult := toolResult.Get("input_schema")
 			if inputSchemaResult.Exists() && inputSchemaResult.IsObject() {
 				// Sanitize the input schema for Antigravity API compatibility
@@ -612,10 +618,14 @@ func ConvertClaudeRequestToAntigravity(modelName string, inputRawJSON []byte, _
 					}
 					tool, _ = sjson.DeleteBytes(tool, toolKey)
 				}
-				toolsJSON, _ = sjson.SetRawBytes(toolsJSON, "0.functionDeclarations.-1", tool)
+				functionToolNode, _ = sjson.SetRawBytes(functionToolNode, "functionDeclarations.-1", tool)
 				toolDeclCount++
 			}
 		}
+		if toolDeclCount > 0 {
+			toolsJSON = []byte(`[]`)
+			toolsJSON, _ = sjson.SetRawBytes(toolsJSON, "-1", functionToolNode)
+		}
 	}
 
 	// Build output Gemini CLI request JSON
diff --git a/internal/translator/antigravity/claude/antigravity_claude_request_test.go b/internal/translator/antigravity/claude/antigravity_claude_request_test.go
index d843dd94..67c200ac 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_request_test.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_request_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/router-for-me/CLIProxyAPI/v7/internal/cache"
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
 	log "github.com/sirupsen/logrus"
 	"github.com/sirupsen/logrus/hooks/test"
 	"github.com/tidwall/gjson"
@@ -180,6 +181,144 @@ func TestConvertClaudeRequestToAntigravity_ConvertsMessageSystemRoleToUserConten
 	}
 }
 
+func TestConvertClaudeRequestToAntigravity_MapsTypedWebSearchToIndependentSearchRequest(t *testing.T) {
+	registry.GetGlobalRegistry().RegisterClient("test-antigravity-claude-websearch", "antigravity", []*registry.ModelInfo{
+		{ID: "gemini-3.1-flash-lite", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() { registry.GetGlobalRegistry().UnregisterClient("test-antigravity-claude-websearch") })
+
+	inputJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"messages": [{"role": "user", "content": "北京天气 2026-06-12"}],
+		"tools": [{"type": "web_search_20250305", "name": "web_search", "max_uses": 8, "allowed_domains": ["www.baidu.com", "weather.com.cn"]}]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("gemini-3.1-flash-lite", inputJSON, true)
+	if got := gjson.GetBytes(output, "requestType").String(); got != "web_search" {
+		t.Fatalf("requestType = %q, want web_search: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.contents.0.parts.0.text").String(); got != "北京天气 2026-06-12" {
+		t.Fatalf("search query = %q, want original user query: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.systemInstruction.parts.0.text").String(); got != antigravityWebSearchSystemInstruction {
+		t.Fatalf("unexpected search system instruction: %q", got)
+	}
+	if got := gjson.GetBytes(output, "request.tools.0.googleSearch.enhancedContent.imageSearch.maxResultCount").Int(); got != 8 {
+		t.Fatalf("image search maxResultCount = %d, want 8: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.tools.0.googleSearch.includedDomains.0").String(); got != "www.baidu.com" {
+		t.Fatalf("includedDomains.0 = %q, want www.baidu.com: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.tools.0.googleSearch.includedDomains.1").String(); got != "weather.com.cn" {
+		t.Fatalf("includedDomains.1 = %q, want weather.com.cn: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.generationConfig.candidateCount").Int(); got != 1 {
+		t.Fatalf("candidateCount = %d, want 1: %s", got, output)
+	}
+}
+
+func TestConvertClaudeRequestToAntigravity_UsesDefaultWebSearchMaxResultCountWithoutMaxUses(t *testing.T) {
+	registry.GetGlobalRegistry().RegisterClient("test-antigravity-claude-websearch-default-max", "antigravity", []*registry.ModelInfo{
+		{ID: "gemini-3.1-flash-lite", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() { registry.GetGlobalRegistry().UnregisterClient("test-antigravity-claude-websearch-default-max") })
+
+	inputJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"messages": [{"role": "user", "content": "北京天气 2026-06-12"}],
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("gemini-3.1-flash-lite", inputJSON, true)
+	if got := gjson.GetBytes(output, "request.tools.0.googleSearch.enhancedContent.imageSearch.maxResultCount").Int(); got != 5 {
+		t.Fatalf("image search maxResultCount = %d, want default 5: %s", got, output)
+	}
+}
+
+func TestConvertClaudeRequestToAntigravity_DoesNotMapTypedWebSearchWhenMixedWithCustomTools(t *testing.T) {
+	registry.GetGlobalRegistry().RegisterClient("test-antigravity-claude-websearch-mixed", "antigravity", []*registry.ModelInfo{
+		{ID: "gemini-3.1-flash-lite", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() { registry.GetGlobalRegistry().UnregisterClient("test-antigravity-claude-websearch-mixed") })
+
+	inputJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"messages": [{"role": "user", "content": "Search current weather"}],
+		"tools": [
+			{"type": "web_search_20250305", "name": "web_search", "max_uses": 8},
+			{"name": "lookup", "description": "Lookup local data", "input_schema": {"type": "object", "properties": {}}}
+		]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("gemini-3.1-flash-lite", inputJSON, true)
+	if got := gjson.GetBytes(output, "requestType").String(); got == "web_search" {
+		t.Fatalf("mixed tools should not become independent web_search request: %s", output)
+	}
+	if got := gjson.GetBytes(output, "request.tools.#(googleSearch)").Raw; got != "" {
+		t.Fatalf("mixed tools should not inject native googleSearch into chat request: %s", output)
+	}
+	if got := gjson.GetBytes(output, `request.tools.#.functionDeclarations.#(name=="lookup")`).Raw; got == "" {
+		t.Fatalf("custom tool declaration should be preserved: %s", output)
+	}
+}
+
+func TestConvertClaudeRequestToAntigravity_DoesNotMapTypedWebSearchForUnsupportedRouteModel(t *testing.T) {
+	registry.GetGlobalRegistry().RegisterClient("test-antigravity-claude-websearch-route", "antigravity", []*registry.ModelInfo{
+		{ID: "gemini-3.5-flash"},
+		{ID: "gemini-3.1-flash-lite", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() { registry.GetGlobalRegistry().UnregisterClient("test-antigravity-claude-websearch-route") })
+
+	inputJSON := []byte(`{
+		"model": "gemini-3.5-flash",
+		"messages": [{"role": "user", "content": "Perform a web search"}],
+		"tools": [{"type": "web_search_20250305", "name": "web_search", "max_uses": 8}]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("gemini-3.5-flash", inputJSON, true)
+	if got := gjson.GetBytes(output, "model").String(); got != "gemini-3.5-flash" {
+		t.Fatalf("web search request model = %q, want original route model: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.tools.#(googleSearch)").Raw; got != "" {
+		t.Fatalf("typed web_search should not become native googleSearch for unsupported route model: %s", output)
+	}
+}
+
+func TestConvertClaudeRequestToAntigravity_DoesNotMapTypedWebSearchForFlashAgentWithoutCapability(t *testing.T) {
+	registry.GetGlobalRegistry().RegisterClient("test-antigravity-claude-websearch-flash-agent", "antigravity", []*registry.ModelInfo{
+		{ID: "gemini-3-flash-agent"},
+		{ID: "gemini-3.1-flash-lite", SupportsWebSearch: true},
+	})
+	t.Cleanup(func() { registry.GetGlobalRegistry().UnregisterClient("test-antigravity-claude-websearch-flash-agent") })
+
+	inputJSON := []byte(`{
+		"model": "gemini-3-flash-agent",
+		"messages": [{"role": "user", "content": "Perform a web search"}],
+		"tools": [{"type": "web_search_20250305", "name": "web_search", "max_uses": 8}]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("gemini-3-flash-agent", inputJSON, true)
+	if got := gjson.GetBytes(output, "model").String(); got != "gemini-3-flash-agent" {
+		t.Fatalf("web search request model = %q, want original route model: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "request.tools.#(googleSearch)").Raw; got != "" {
+		t.Fatalf("typed web_search should not become native googleSearch for flash-agent without capability: %s", output)
+	}
+}
+
+func TestConvertClaudeRequestToAntigravity_DoesNotMapTypedWebSearchForOtherModels(t *testing.T) {
+	inputJSON := []byte(`{
+		"model": "claude-sonnet-4-6",
+		"messages": [{"role": "user", "content": "Search current weather"}],
+		"tools": [{"type": "web_search_20250305", "name": "web_search", "max_uses": 8}]
+	}`)
+
+	output := ConvertClaudeRequestToAntigravity("claude-sonnet-4-6", inputJSON, true)
+	if got := gjson.GetBytes(output, "request.tools.#(googleSearch)").Raw; got != "" {
+		t.Fatalf("model without Antigravity web search capability should not get native googleSearch: %s", output)
+	}
+}
+
 func testNonAnthropicRawSignature(t *testing.T) string {
 	t.Helper()
 
diff --git a/internal/translator/antigravity/claude/antigravity_claude_response.go b/internal/translator/antigravity/claude/antigravity_claude_response.go
index 757ce31d..c883f182 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_response.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_response.go
@@ -69,6 +69,9 @@ type Params struct {
 	HasSentFinalEvents   bool   // Indicates if final content/message events have been sent
 	HasToolUse           bool   // Indicates if tool use was observed in the stream
 	HasContent           bool   // Tracks whether any content (text, thinking, or tool use) has been output
+	HasWebSearchTool     bool
+	WebSearchRequests    int64
+	WebSearchTextBuffer  strings.Builder
 
 	// Signature caching support
 	CurrentThinkingText strings.Builder // Accumulates thinking text for signature caching
@@ -125,6 +128,7 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 	appendEvent := func(event, payload string) {
 		output = translatorcommon.AppendSSEEventString(output, event, payload, 3)
 	}
+	webSearchStreamMode := shouldTranslateWebSearchGrounding(originalRequestRawJSON, requestRawJSON)
 	appendThinkingSignature := func(signature string) {
 		if signature == "" || params.ResponseType != 2 {
 			return
@@ -150,7 +154,7 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 		if promptTokenCount := gjson.GetBytes(rawJSON, "response.cpaUsageMetadata.promptTokenCount"); promptTokenCount.Exists() {
 			messageStartTemplate, _ = sjson.SetBytes(messageStartTemplate, "message.usage.input_tokens", promptTokenCount.Int())
 		}
-		if candidatesTokenCount := gjson.GetBytes(rawJSON, "response.cpaUsageMetadata.candidatesTokenCount"); candidatesTokenCount.Exists() {
+		if candidatesTokenCount := gjson.GetBytes(rawJSON, "response.cpaUsageMetadata.candidatesTokenCount"); candidatesTokenCount.Exists() && !webSearchStreamMode {
 			messageStartTemplate, _ = sjson.SetBytes(messageStartTemplate, "message.usage.output_tokens", candidatesTokenCount.Int())
 		}
 
@@ -166,10 +170,28 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 		params.HasFirstResponse = true
 	}
 
+	handledWebSearchGrounding := false
+	if webSearchStreamMode && !params.HasWebSearchTool {
+		root := gjson.ParseBytes(rawJSON)
+		if groundingMetadata := antigravityGroundingMetadata(root); groundingMetadata.Exists() {
+			toolUseID := newClaudeWebSearchToolUseID()
+			textContent := params.WebSearchTextBuffer.String() + antigravityTextContent(root)
+			params.WebSearchTextBuffer.Reset()
+			params.ResponseIndex = appendClaudeWebSearchStreamBlocks(appendEvent, params.ResponseIndex, toolUseID, textContent, groundingMetadata)
+			params.HasWebSearchTool = true
+			params.WebSearchRequests = 1
+			params.HasContent = true
+			params.ResponseType = 0
+			handledWebSearchGrounding = true
+		}
+	}
+
 	// Process the response parts array from the backend client
 	// Each part can contain text content, thinking content, or function calls
 	partsResult := gjson.GetBytes(rawJSON, "response.candidates.0.content.parts")
-	if partsResult.IsArray() {
+	if partsResult.IsArray() && webSearchStreamMode && !params.HasWebSearchTool && !handledWebSearchGrounding {
+		appendWebSearchBufferedText(partsResult, &params.WebSearchTextBuffer)
+	} else if partsResult.IsArray() && !handledWebSearchGrounding {
 		partResults := partsResult.Array()
 		for i := 0; i < len(partResults); i++ {
 			partResult := partResults[i]
@@ -337,6 +359,10 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 		}
 	}
 
+	if webSearchStreamMode && !params.HasWebSearchTool && params.HasFinishReason && params.WebSearchTextBuffer.Len() > 0 {
+		appendBufferedWebSearchTextBlock(params, appendEvent)
+	}
+
 	if params.HasUsageMetadata && params.HasFinishReason {
 		appendFinalEvents(params, &output, false)
 	}
@@ -344,6 +370,30 @@ func ConvertAntigravityResponseToClaude(_ context.Context, _ string, originalReq
 	return [][]byte{output}
 }
 
+func appendWebSearchBufferedText(partsResult gjson.Result, buffer *strings.Builder) {
+	for _, partResult := range partsResult.Array() {
+		if partResult.Get("thought").Bool() || partResult.Get("functionCall").Exists() {
+			continue
+		}
+		if partTextResult := partResult.Get("text"); partTextResult.Exists() {
+			buffer.WriteString(partTextResult.String())
+		}
+	}
+}
+
+func appendBufferedWebSearchTextBlock(params *Params, appendEvent func(string, string)) {
+	text := params.WebSearchTextBuffer.String()
+	params.WebSearchTextBuffer.Reset()
+	if text == "" {
+		return
+	}
+	appendEvent("content_block_start", fmt.Sprintf(`{"type":"content_block_start","index":%d,"content_block":{"type":"text","text":""}}`, params.ResponseIndex))
+	data, _ := sjson.SetBytes([]byte(fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, params.ResponseIndex)), "delta.text", text)
+	appendEvent("content_block_delta", string(data))
+	params.ResponseType = 1
+	params.HasContent = true
+}
+
 func appendFinalEvents(params *Params, output *[]byte, force bool) {
 	if params.HasSentFinalEvents {
 		return
@@ -373,6 +423,9 @@ func appendFinalEvents(params *Params, output *[]byte, force bool) {
 	}
 
 	delta := []byte(fmt.Sprintf(`{"type":"message_delta","delta":{"stop_reason":"%s","stop_sequence":null},"usage":{"input_tokens":%d,"output_tokens":%d}}`, stopReason, params.PromptTokenCount, usageOutputTokens))
+	if params.WebSearchRequests > 0 {
+		delta, _ = sjson.SetBytes(delta, "usage.server_tool_use.web_search_requests", params.WebSearchRequests)
+	}
 	// Add cache_read_input_tokens if cached tokens are present (indicates prompt caching is working)
 	if params.CachedTokenCount > 0 {
 		var err error
@@ -443,6 +496,16 @@ func ConvertAntigravityResponseToClaudeNonStream(_ context.Context, _ string, or
 		}
 	}
 
+	if shouldTranslateWebSearchGrounding(originalRequestRawJSON, requestRawJSON) {
+		if groundingMetadata := antigravityGroundingMetadata(root); groundingMetadata.Exists() {
+			toolUseID := newClaudeWebSearchToolUseID()
+			responseJSON, _ = sjson.SetRawBytes(responseJSON, "content", buildClaudeWebSearchContent(toolUseID, antigravityTextContent(root), groundingMetadata))
+			responseJSON, _ = sjson.SetBytes(responseJSON, "stop_reason", "end_turn")
+			responseJSON, _ = sjson.SetBytes(responseJSON, "usage.server_tool_use.web_search_requests", 1)
+			return responseJSON
+		}
+	}
+
 	contentArrayInitialized := false
 	ensureContentArray := func() {
 		if contentArrayInitialized {
diff --git a/internal/translator/antigravity/claude/antigravity_claude_response_test.go b/internal/translator/antigravity/claude/antigravity_claude_response_test.go
index fe4cb31f..7999e64d 100644
--- a/internal/translator/antigravity/claude/antigravity_claude_response_test.go
+++ b/internal/translator/antigravity/claude/antigravity_claude_response_test.go
@@ -3,6 +3,7 @@ package claude
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"strings"
 	"testing"
 
@@ -14,6 +15,296 @@ import (
 // Signature Caching Tests
 // ============================================================================
 
+func TestConvertAntigravityResponseToClaudeNonStream_WebSearchGrounding(t *testing.T) {
+	requestJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+	translatedRequestJSON := []byte(`{"model":"gemini-3.1-flash-lite","request":{"tools":[{"googleSearch":{}}]}}`)
+	responseJSON := testAntigravityGroundingResponse()
+
+	output := ConvertAntigravityResponseToClaudeNonStream(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, responseJSON, nil)
+
+	if got := gjson.GetBytes(output, "content.0.type").String(); got != "server_tool_use" {
+		t.Fatalf("first content block = %q, want server_tool_use: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "content.1.type").String(); got != "web_search_tool_result" {
+		t.Fatalf("second content block = %q, want web_search_tool_result: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "usage.server_tool_use.web_search_requests").Int(); got != 1 {
+		t.Fatalf("web_search_requests = %d, want 1: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "content.1.content.0.url").String(); got != "https://example.com/weather" {
+		t.Fatalf("search result url = %q: %s", got, output)
+	}
+	if got := gjson.GetBytes(output, "content.2.citations.0.url").String(); got != "https://example.com/weather" {
+		t.Fatalf("citation url = %q: %s", got, output)
+	}
+}
+
+func TestConvertAntigravityResponseToClaudeNonStream_WebSearchGroundingRequiresNativeGoogleSearch(t *testing.T) {
+	requestJSON := []byte(`{
+		"model": "gemini-3-flash-agent",
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+	translatedRequestJSON := []byte(`{"model":"gemini-3-flash-agent","request":{"contents":[]}}`)
+	responseJSON := testAntigravityGroundingResponse()
+
+	output := ConvertAntigravityResponseToClaudeNonStream(context.Background(), "gemini-3-flash-agent", requestJSON, translatedRequestJSON, responseJSON, nil)
+
+	if got := gjson.GetBytes(output, "content.0.type").String(); got == "server_tool_use" {
+		t.Fatalf("non-native translated request should not synthesize server_tool_use: %s", output)
+	}
+	if got := gjson.GetBytes(output, "usage.server_tool_use.web_search_requests").Int(); got != 0 {
+		t.Fatalf("web_search_requests = %d, want 0: %s", got, output)
+	}
+}
+
+func TestConvertAntigravityResponseToClaudeStream_WebSearchGrounding(t *testing.T) {
+	requestJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+	translatedRequestJSON := []byte(`{"model":"gemini-3.1-flash-lite","request":{"tools":[{"googleSearch":{}}]}}`)
+
+	var param any
+	output := bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, testAntigravityGroundingResponse(), &param), nil)
+	output = append(output, bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, []byte("[DONE]"), &param), nil)...)
+	outputText := string(output)
+
+	for _, needle := range []string{
+		`"type":"server_tool_use"`,
+		`"type":"web_search_tool_result"`,
+		`"web_search_requests":1`,
+		`"type":"citations_delta"`,
+		`event: message_stop`,
+	} {
+		if !strings.Contains(outputText, needle) {
+			t.Fatalf("stream output missing %s:\n%s", needle, outputText)
+		}
+	}
+}
+
+func TestConvertAntigravityResponseToClaudeStream_WebSearchBuffersTextUntilGrounding(t *testing.T) {
+	requestJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+	translatedRequestJSON := []byte(`{"model":"gemini-3.1-flash-lite","request":{"tools":[{"googleSearch":{}}]}}`)
+
+	var param any
+	firstChunk := []byte(`{
+		"response": {
+			"modelVersion": "gemini-3.1-flash-lite",
+			"responseId": "resp-web-search-stream",
+			"candidates": [{
+				"content": {
+					"parts": [{"text": "Beijing weather "}]
+				}
+			}],
+			"usageMetadata": {"promptTokenCount": 10, "candidatesTokenCount": 2, "totalTokenCount": 12}
+		}
+	}`)
+	finalChunk := []byte(`{
+		"response": {
+			"modelVersion": "gemini-3.1-flash-lite",
+			"responseId": "resp-web-search-stream",
+			"candidates": [{
+				"content": {
+					"parts": [{"text": "is clear today."}]
+				},
+				"groundingMetadata": {
+					"webSearchQueries": ["Beijing weather"],
+					"groundingChunks": [{"web": {"uri": "https://example.com/weather", "title": "Beijing Weather"}}],
+					"groundingSupports": [{
+						"segment": {"startIndex": 0, "endIndex": 31, "text": "Beijing weather is clear today."},
+						"groundingChunkIndices": [0]
+					}]
+				},
+				"finishReason": "STOP"
+			}],
+			"usageMetadata": {"promptTokenCount": 10, "candidatesTokenCount": 6, "totalTokenCount": 16}
+		}
+	}`)
+
+	output := bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, firstChunk, &param), nil)
+	output = append(output, bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, finalChunk, &param), nil)...)
+	output = append(output, bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, []byte("[DONE]"), &param), nil)...)
+	outputText := string(output)
+
+	textStart := strings.Index(outputText, `"content_block":{"type":"text"`)
+	serverToolStart := strings.Index(outputText, `"content_block":{"type":"server_tool_use"`)
+	if serverToolStart < 0 {
+		t.Fatalf("stream output missing server_tool_use:\n%s", outputText)
+	}
+	if textStart >= 0 && textStart < serverToolStart {
+		t.Fatalf("text block was emitted before server_tool_use:\n%s", outputText)
+	}
+	if strings.Contains(outputText, `"index":0,"content_block":{"type":"text"`) {
+		t.Fatalf("index 0 must be reserved for server_tool_use:\n%s", outputText)
+	}
+	if !strings.Contains(outputText, `"index":0,"content_block":{"type":"server_tool_use"`) {
+		t.Fatalf("server_tool_use must use index 0:\n%s", outputText)
+	}
+	if !strings.Contains(outputText, `"index":1,"content_block":{"type":"web_search_tool_result"`) {
+		t.Fatalf("web_search_tool_result must use index 1:\n%s", outputText)
+	}
+	if !strings.Contains(outputText, `Beijing weather is clear today.`) {
+		t.Fatalf("buffered text was not emitted after web search blocks:\n%s", outputText)
+	}
+}
+
+func TestConvertAntigravityResponseToClaudeStream_WebSearchMessageStartOutputTokensZero(t *testing.T) {
+	requestJSON := []byte(`{
+		"model": "gemini-3.1-flash-lite",
+		"tools": [{"type": "web_search_20250305", "name": "web_search"}]
+	}`)
+	translatedRequestJSON := []byte(`{"model":"gemini-3.1-flash-lite","request":{"tools":[{"googleSearch":{}}]}}`)
+	responseJSON := []byte(`{
+		"response": {
+			"modelVersion": "gemini-3.1-flash-lite",
+			"responseId": "resp-web-search-start",
+			"candidates": [{
+				"content": {"parts": [{"text": "Beijing weather"}]}
+			}],
+			"cpaUsageMetadata": {"promptTokenCount": 85, "candidatesTokenCount": 43}
+		}
+	}`)
+
+	var param any
+	output := bytes.Join(ConvertAntigravityResponseToClaude(context.Background(), "gemini-3.1-flash-lite", requestJSON, translatedRequestJSON, responseJSON, &param), nil)
+	messageStart := sseDataForEvent(t, string(output), "message_start")
+
+	if got := gjson.Get(messageStart, "message.usage.output_tokens").Int(); got != 0 {
+		t.Fatalf("message_start output_tokens = %d, want 0: %s", got, messageStart)
+	}
+}
+
+func TestWebSearchResultsFromGrounding_DeduplicatesAndSkipsEmptyURLs(t *testing.T) {
+	groundingMetadata := gjson.Parse(`{
+		"groundingChunks": [
+			{"web": {"uri": "https://example.com/a", "title": "A"}},
+			{"web": {"uri": "https://example.com/b", "title": "B"}},
+			{"web": {"uri": "https://example.com/a", "title": "A duplicate"}},
+			{"web": {"uri": "", "title": "Empty"}}
+		]
+	}`)
+
+	results := webSearchResultsFromGrounding(groundingMetadata)
+
+	if got := gjson.GetBytes(results, "#").Int(); got != 2 {
+		t.Fatalf("result count = %d, want 2: %s", got, string(results))
+	}
+	if got := gjson.GetBytes(results, "0.url").String(); got != "https://example.com/a" {
+		t.Fatalf("first url = %q: %s", got, string(results))
+	}
+	if got := gjson.GetBytes(results, "1.url").String(); got != "https://example.com/b" {
+		t.Fatalf("second url = %q: %s", got, string(results))
+	}
+}
+
+func TestBuildWebSearchCitedTextBlocks_TrimsOverlappingGroundingSupports(t *testing.T) {
+	first := "北京今天晴"
+	second := "北京今天晴，气温19到31度"
+	textContent := second + "。"
+
+	blocks := buildWebSearchCitedTextBlocks(textContent, []webSearchGroundingSupport{
+		{
+			StartIndex: 0,
+			EndIndex:   int64(len([]byte(first))),
+			Text:       first,
+			ChunkURLs:  []string{"https://example.com/weather"},
+			ChunkTitle: "Weather",
+		},
+		{
+			StartIndex: 0,
+			EndIndex:   int64(len([]byte(second))),
+			Text:       second,
+			ChunkURLs:  []string{"https://example.com/weather"},
+			ChunkTitle: "Weather",
+		},
+	})
+
+	var got strings.Builder
+	for _, block := range blocks {
+		got.WriteString(block.Text)
+	}
+	if got.String() != textContent {
+		t.Fatalf("joined text = %q, want %q", got.String(), textContent)
+	}
+	if len(blocks) < 2 || blocks[1].Text != "，气温19到31度" {
+		t.Fatalf("overlap suffix block not trimmed correctly: %#v", blocks)
+	}
+	if gotCitation := blocks[1].Citations[0]["cited_text"]; gotCitation != blocks[1].Text {
+		t.Fatalf("cited_text = %q, want emitted text %q", gotCitation, blocks[1].Text)
+	}
+}
+
+func sseDataForEvent(t *testing.T, output string, eventName string) string {
+	t.Helper()
+
+	currentEvent := ""
+	for _, line := range strings.Split(output, "\n") {
+		if strings.HasPrefix(line, "event: ") {
+			currentEvent = strings.TrimPrefix(line, "event: ")
+			continue
+		}
+		if currentEvent == eventName && strings.HasPrefix(line, "data: ") {
+			return strings.TrimPrefix(line, "data: ")
+		}
+	}
+
+	t.Fatalf("event %q not found in:\n%s", eventName, output)
+	return ""
+}
+
+func testAntigravityGroundingResponse() []byte {
+	resp := map[string]any{
+		"response": map[string]any{
+			"responseId":   "resp-web-search",
+			"modelVersion": "gemini-3.1-flash-lite",
+			"candidates": []any{
+				map[string]any{
+					"content": map[string]any{
+						"parts": []any{
+							map[string]any{"text": "Beijing weather is clear today."},
+						},
+					},
+					"groundingMetadata": map[string]any{
+						"webSearchQueries": []any{"Beijing weather June 10 2026"},
+						"groundingChunks": []any{
+							map[string]any{
+								"web": map[string]any{
+									"uri":   "https://example.com/weather",
+									"title": "Beijing Weather",
+								},
+							},
+						},
+						"groundingSupports": []any{
+							map[string]any{
+								"segment": map[string]any{
+									"startIndex": int64(0),
+									"endIndex":   int64(31),
+									"text":       "Beijing weather is clear today.",
+								},
+								"groundingChunkIndices": []any{0},
+							},
+						},
+					},
+					"finishReason": "STOP",
+				},
+			},
+			"usageMetadata": map[string]any{
+				"promptTokenCount":     10,
+				"candidatesTokenCount": 6,
+				"totalTokenCount":      16,
+			},
+		},
+	}
+	raw, _ := json.Marshal(resp)
+	return raw
+}
+
 func TestConvertAntigravityResponseToClaude_ParamsInitialized(t *testing.T) {
 	cache.ClearSignatureCache("")
 
diff --git a/internal/translator/antigravity/claude/web_search.go b/internal/translator/antigravity/claude/web_search.go
new file mode 100644
index 00000000..e524abe3
--- /dev/null
+++ b/internal/translator/antigravity/claude/web_search.go
@@ -0,0 +1,502 @@
+package claude
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+type webSearchGroundingSupport struct {
+	StartIndex int64
+	EndIndex   int64
+	Text       string
+	ChunkURLs  []string
+	ChunkTitle string
+}
+
+type webSearchCitedTextBlock struct {
+	Text      string
+	Citations []map[string]any
+}
+
+const antigravityWebSearchSystemInstruction = "You are a search engine bot. You will be given a query from a user. Your task is to search the web for relevant information that will help the user. You MUST perform a web search. Do not respond or interact with the user, please respond as if they typed the query into a search bar."
+
+func antigravitySupportsNativeGoogleSearch(model string) bool {
+	return registry.AntigravityWebSearchModelFor(model) != ""
+}
+
+func isClaudeTypedWebSearchToolType(toolType string) bool {
+	return toolType == "web_search_20250305" || toolType == "web_search_20260209"
+}
+
+func hasClaudeTypedWebSearchTool(payload []byte) bool {
+	tools := gjson.GetBytes(payload, "tools")
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		if isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			return true
+		}
+	}
+	return false
+}
+
+func hasOnlyClaudeTypedWebSearchTools(payload []byte) bool {
+	tools := gjson.GetBytes(payload, "tools")
+	if !tools.IsArray() {
+		return false
+	}
+	hasWebSearch := false
+	for _, tool := range tools.Array() {
+		if isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			hasWebSearch = true
+			continue
+		}
+		return false
+	}
+	return hasWebSearch
+}
+
+func allowsClaudeWebSearchToolChoice(payload []byte) bool {
+	toolChoice := gjson.GetBytes(payload, "tool_choice")
+	if !toolChoice.Exists() {
+		return true
+	}
+	if toolChoice.Type == gjson.String {
+		switch toolChoice.String() {
+		case "", "auto", "any":
+			return true
+		case "none":
+			return false
+		default:
+			return false
+		}
+	}
+	if !toolChoice.IsObject() {
+		return false
+	}
+	switch toolChoice.Get("type").String() {
+	case "", "auto", "any":
+		return true
+	case "tool":
+		return toolChoice.Get("name").String() == "web_search"
+	default:
+		return false
+	}
+}
+
+func shouldBuildAntigravityWebSearchRequest(model string, payload []byte) bool {
+	return antigravitySupportsNativeGoogleSearch(model) &&
+		hasOnlyClaudeTypedWebSearchTools(payload) &&
+		allowsClaudeWebSearchToolChoice(payload)
+}
+
+func buildAntigravityWebSearchRequest(model string, payload []byte) []byte {
+	query := extractClaudeWebSearchQuery(payload)
+	maxResultCount := extractClaudeWebSearchMaxUses(payload)
+	includedDomains := extractClaudeWebSearchAllowedDomains(payload)
+	out := []byte(`{"model":"","requestType":"web_search","request":{"contents":[{"role":"user","parts":[{"text":""}]}],"systemInstruction":{"role":"user","parts":[{"text":""}]},"tools":[{"googleSearch":{"enhancedContent":{"imageSearch":{"maxResultCount":5}}}}],"generationConfig":{"candidateCount":1}}}`)
+	out, _ = sjson.SetBytes(out, "model", model)
+	out, _ = sjson.SetBytes(out, "request.contents.0.parts.0.text", query)
+	out, _ = sjson.SetBytes(out, "request.systemInstruction.parts.0.text", antigravityWebSearchSystemInstruction)
+	out, _ = sjson.SetBytes(out, "request.tools.0.googleSearch.enhancedContent.imageSearch.maxResultCount", maxResultCount)
+	if len(includedDomains) > 0 {
+		if domainsJSON, err := json.Marshal(includedDomains); err == nil {
+			out, _ = sjson.SetRawBytes(out, "request.tools.0.googleSearch.includedDomains", domainsJSON)
+		}
+	}
+	return out
+}
+
+func extractClaudeWebSearchMaxUses(payload []byte) int64 {
+	const defaultMaxResultCount int64 = 5
+
+	tools := gjson.GetBytes(payload, "tools")
+	if !tools.IsArray() {
+		return defaultMaxResultCount
+	}
+	for _, tool := range tools.Array() {
+		if !isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			continue
+		}
+		maxUses := tool.Get("max_uses").Int()
+		if maxUses > 0 {
+			return maxUses
+		}
+	}
+	return defaultMaxResultCount
+}
+
+func extractClaudeWebSearchAllowedDomains(payload []byte) []string {
+	tools := gjson.GetBytes(payload, "tools")
+	if !tools.IsArray() {
+		return nil
+	}
+	for _, tool := range tools.Array() {
+		if !isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			continue
+		}
+		allowedDomains := tool.Get("allowed_domains")
+		if !allowedDomains.IsArray() {
+			return nil
+		}
+		domains := make([]string, 0, len(allowedDomains.Array()))
+		for _, domain := range allowedDomains.Array() {
+			if domain.Type != gjson.String {
+				continue
+			}
+			if trimmed := strings.TrimSpace(domain.String()); trimmed != "" {
+				domains = append(domains, trimmed)
+			}
+		}
+		return domains
+	}
+	return nil
+}
+
+func extractClaudeWebSearchQuery(payload []byte) string {
+	messages := gjson.GetBytes(payload, "messages")
+	if !messages.IsArray() {
+		return ""
+	}
+	messageResults := messages.Array()
+	for i := len(messageResults) - 1; i >= 0; i-- {
+		message := messageResults[i]
+		if role := message.Get("role").String(); role != "" && role != "user" {
+			continue
+		}
+		if query := extractClaudeTextContent(message.Get("content")); query != "" {
+			return query
+		}
+	}
+	return ""
+}
+
+func extractClaudeTextContent(content gjson.Result) string {
+	if content.Type == gjson.String {
+		return strings.TrimSpace(content.String())
+	}
+	if !content.IsArray() {
+		return ""
+	}
+	var b strings.Builder
+	for _, part := range content.Array() {
+		if text := strings.TrimSpace(part.Get("text").String()); text != "" {
+			if b.Len() > 0 {
+				b.WriteByte('\n')
+			}
+			b.WriteString(text)
+		}
+	}
+	return strings.TrimSpace(b.String())
+}
+
+func hasAntigravityGoogleSearchTool(payload []byte) bool {
+	tools := gjson.GetBytes(payload, "request.tools")
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		if tool.Get("googleSearch").Exists() {
+			return true
+		}
+	}
+	return false
+}
+
+func shouldTranslateWebSearchGrounding(originalRequestRawJSON, requestRawJSON []byte) bool {
+	return hasClaudeTypedWebSearchTool(originalRequestRawJSON) && hasAntigravityGoogleSearchTool(requestRawJSON)
+}
+
+func antigravityGroundingMetadata(root gjson.Result) gjson.Result {
+	groundingMetadata := root.Get("response.candidates.0.groundingMetadata")
+	if groundingMetadata.Exists() {
+		return groundingMetadata
+	}
+	return root.Get("candidates.0.groundingMetadata")
+}
+
+func antigravityTextContent(root gjson.Result) string {
+	var textBuilder strings.Builder
+	parts := root.Get("response.candidates.0.content.parts")
+	if !parts.IsArray() {
+		parts = root.Get("candidates.0.content.parts")
+	}
+	if parts.IsArray() {
+		for _, part := range parts.Array() {
+			if text := part.Get("text"); text.Exists() {
+				textBuilder.WriteString(text.String())
+			}
+		}
+	}
+	return textBuilder.String()
+}
+
+func antigravityUsageTokens(root gjson.Result) (int64, int64) {
+	usage := root.Get("response.usageMetadata")
+	if !usage.Exists() {
+		usage = root.Get("usageMetadata")
+	}
+	inputTokens := usage.Get("promptTokenCount").Int()
+	outputTokens := usage.Get("candidatesTokenCount").Int() + usage.Get("thoughtsTokenCount").Int()
+	if outputTokens == 0 {
+		totalTokens := usage.Get("totalTokenCount").Int()
+		if totalTokens > 0 {
+			outputTokens = totalTokens - inputTokens
+			if outputTokens < 0 {
+				outputTokens = 0
+			}
+		}
+	}
+	return inputTokens, outputTokens
+}
+
+func webSearchQueryFromGrounding(groundingMetadata gjson.Result) string {
+	if queries := groundingMetadata.Get("webSearchQueries"); queries.IsArray() && len(queries.Array()) > 0 {
+		return queries.Array()[0].String()
+	}
+	return ""
+}
+
+func webSearchResultsFromGrounding(groundingMetadata gjson.Result) []byte {
+	results := []byte(`[]`)
+	groundingChunks := groundingMetadata.Get("groundingChunks")
+	if !groundingChunks.IsArray() {
+		return results
+	}
+	seenURLs := make(map[string]struct{})
+	for _, chunk := range groundingChunks.Array() {
+		web := chunk.Get("web")
+		if !web.Exists() {
+			continue
+		}
+		uri := strings.TrimSpace(web.Get("uri").String())
+		if uri == "" {
+			continue
+		}
+		if _, ok := seenURLs[uri]; ok {
+			continue
+		}
+		seenURLs[uri] = struct{}{}
+
+		result := []byte(`{"type":"web_search_result","page_age":null}`)
+		if title := web.Get("title"); title.Exists() {
+			result, _ = sjson.SetBytes(result, "title", title.String())
+		}
+		result, _ = sjson.SetBytes(result, "url", uri)
+		results, _ = sjson.SetRawBytes(results, "-1", result)
+	}
+	return results
+}
+
+func parseWebSearchGroundingSupports(groundingMetadata gjson.Result) []webSearchGroundingSupport {
+	groundingChunks := groundingMetadata.Get("groundingChunks")
+	if !groundingChunks.IsArray() {
+		return nil
+	}
+	chunks := groundingChunks.Array()
+	chunkData := make([]struct {
+		URL   string
+		Title string
+	}, len(chunks))
+	for i, chunk := range chunks {
+		web := chunk.Get("web")
+		if web.Exists() {
+			chunkData[i].URL = web.Get("uri").String()
+			chunkData[i].Title = web.Get("title").String()
+		}
+	}
+
+	groundingSupports := groundingMetadata.Get("groundingSupports")
+	if !groundingSupports.IsArray() {
+		return nil
+	}
+	supports := make([]webSearchGroundingSupport, 0, len(groundingSupports.Array()))
+	for _, support := range groundingSupports.Array() {
+		segment := support.Get("segment")
+		if !segment.Exists() {
+			continue
+		}
+		parsed := webSearchGroundingSupport{
+			StartIndex: segment.Get("startIndex").Int(),
+			EndIndex:   segment.Get("endIndex").Int(),
+			Text:       segment.Get("text").String(),
+		}
+		if chunkIndices := support.Get("groundingChunkIndices"); chunkIndices.IsArray() {
+			for _, idx := range chunkIndices.Array() {
+				chunkIndex := int(idx.Int())
+				if chunkIndex < 0 || chunkIndex >= len(chunkData) {
+					continue
+				}
+				parsed.ChunkURLs = append(parsed.ChunkURLs, chunkData[chunkIndex].URL)
+				if parsed.ChunkTitle == "" {
+					parsed.ChunkTitle = chunkData[chunkIndex].Title
+				}
+			}
+		}
+		supports = append(supports, parsed)
+	}
+	return supports
+}
+
+func buildWebSearchCitedTextBlocks(textContent string, supports []webSearchGroundingSupport) []webSearchCitedTextBlock {
+	if len(supports) == 0 {
+		if textContent == "" {
+			return nil
+		}
+		return []webSearchCitedTextBlock{{Text: textContent}}
+	}
+
+	textBytes := []byte(textContent)
+	blocks := make([]webSearchCitedTextBlock, 0, len(supports)+1)
+	lastEnd := int64(0)
+	for _, support := range supports {
+		if support.EndIndex <= lastEnd {
+			continue
+		}
+		if support.StartIndex > lastEnd {
+			start := int(lastEnd)
+			end := min(int(support.StartIndex), len(textBytes))
+			if start < end {
+				blocks = append(blocks, webSearchCitedTextBlock{Text: string(textBytes[start:end])})
+			}
+		}
+
+		citedStart := support.StartIndex
+		if citedStart < lastEnd {
+			citedStart = lastEnd
+		}
+		citedText := ""
+		if citedStart < support.EndIndex {
+			start := min(int(citedStart), len(textBytes))
+			end := min(int(support.EndIndex), len(textBytes))
+			if start < end {
+				citedText = string(textBytes[start:end])
+			}
+		}
+		if citedText != "" && len(support.ChunkURLs) > 0 {
+			citation := map[string]any{
+				"type":       "web_search_result_location",
+				"cited_text": citedText,
+				"url":        support.ChunkURLs[0],
+				"title":      support.ChunkTitle,
+			}
+			blocks = append(blocks, webSearchCitedTextBlock{
+				Text:      citedText,
+				Citations: []map[string]any{citation},
+			})
+		}
+		if support.EndIndex > lastEnd {
+			lastEnd = support.EndIndex
+		}
+	}
+	if int(lastEnd) < len(textBytes) {
+		blocks = append(blocks, webSearchCitedTextBlock{Text: string(textBytes[lastEnd:])})
+	}
+	return blocks
+}
+
+func buildClaudeWebSearchContent(toolUseID string, textContent string, groundingMetadata gjson.Result) []byte {
+	content := []byte(`[]`)
+
+	serverToolUse := []byte(`{"type":"server_tool_use","id":"","name":"web_search","input":{}}`)
+	serverToolUse, _ = sjson.SetBytes(serverToolUse, "id", toolUseID)
+	if query := webSearchQueryFromGrounding(groundingMetadata); query != "" {
+		serverToolUse, _ = sjson.SetBytes(serverToolUse, "input.query", query)
+	}
+	content, _ = sjson.SetRawBytes(content, "-1", serverToolUse)
+
+	webSearchToolResult := []byte(`{"type":"web_search_tool_result","tool_use_id":"","content":[]}`)
+	webSearchToolResult, _ = sjson.SetBytes(webSearchToolResult, "tool_use_id", toolUseID)
+	webSearchToolResult, _ = sjson.SetRawBytes(webSearchToolResult, "content", webSearchResultsFromGrounding(groundingMetadata))
+	content, _ = sjson.SetRawBytes(content, "-1", webSearchToolResult)
+
+	for _, block := range buildWebSearchCitedTextBlocks(textContent, parseWebSearchGroundingSupports(groundingMetadata)) {
+		if block.Text == "" {
+			continue
+		}
+		textBlock := []byte(`{"type":"text","text":""}`)
+		textBlock, _ = sjson.SetBytes(textBlock, "text", block.Text)
+		if len(block.Citations) > 0 {
+			citationsJSON, _ := json.Marshal(block.Citations)
+			textBlock, _ = sjson.SetRawBytes(textBlock, "citations", citationsJSON)
+		}
+		content, _ = sjson.SetRawBytes(content, "-1", textBlock)
+	}
+
+	return content
+}
+
+func appendClaudeWebSearchStreamBlocks(appendEvent func(string, string), startIndex int, toolUseID string, textContent string, groundingMetadata gjson.Result) int {
+	contentIndex := startIndex
+
+	serverToolUseStart := fmt.Sprintf(`{"type":"content_block_start","index":%d,"content_block":{"type":"server_tool_use","id":"%s","name":"web_search","input":{}}}`,
+		contentIndex, toolUseID)
+	appendEvent("content_block_start", serverToolUseStart)
+	if query := webSearchQueryFromGrounding(groundingMetadata); query != "" {
+		queryJSON, _ := sjson.Set(`{}`, "query", query)
+		inputDelta := fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"input_json_delta","partial_json":""}}`, contentIndex)
+		inputDelta, _ = sjson.Set(inputDelta, "delta.partial_json", queryJSON)
+		appendEvent("content_block_delta", inputDelta)
+	}
+	appendEvent("content_block_stop", fmt.Sprintf(`{"type":"content_block_stop","index":%d}`, contentIndex))
+	contentIndex++
+
+	webSearchToolResultStart := fmt.Sprintf(`{"type":"content_block_start","index":%d,"content_block":{"type":"web_search_tool_result","tool_use_id":"%s","content":[]}}`,
+		contentIndex, toolUseID)
+	webSearchToolResultStart, _ = sjson.SetRaw(webSearchToolResultStart, "content_block.content", string(webSearchResultsFromGrounding(groundingMetadata)))
+	appendEvent("content_block_start", webSearchToolResultStart)
+	appendEvent("content_block_stop", fmt.Sprintf(`{"type":"content_block_stop","index":%d}`, contentIndex))
+	contentIndex++
+
+	for _, block := range buildWebSearchCitedTextBlocks(textContent, parseWebSearchGroundingSupports(groundingMetadata)) {
+		if block.Text == "" {
+			continue
+		}
+		textBlockStart := fmt.Sprintf(`{"type":"content_block_start","index":%d,"content_block":{"type":"text","text":""}}`, contentIndex)
+		if len(block.Citations) > 0 {
+			textBlockStart = fmt.Sprintf(`{"type":"content_block_start","index":%d,"content_block":{"citations":[],"type":"text","text":""}}`, contentIndex)
+		}
+		appendEvent("content_block_start", textBlockStart)
+		for _, citation := range block.Citations {
+			citationJSON, _ := json.Marshal(citation)
+			citationDelta := fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"citations_delta","citation":%s}}`, contentIndex, string(citationJSON))
+			appendEvent("content_block_delta", citationDelta)
+		}
+		for _, chunk := range splitRunesForWebSearch(block.Text, 50) {
+			textDelta := fmt.Sprintf(`{"type":"content_block_delta","index":%d,"delta":{"type":"text_delta","text":""}}`, contentIndex)
+			textDelta, _ = sjson.Set(textDelta, "delta.text", chunk)
+			appendEvent("content_block_delta", textDelta)
+		}
+		appendEvent("content_block_stop", fmt.Sprintf(`{"type":"content_block_stop","index":%d}`, contentIndex))
+		contentIndex++
+	}
+
+	return contentIndex
+}
+
+func splitRunesForWebSearch(text string, chunkSize int) []string {
+	if chunkSize <= 0 || text == "" {
+		return nil
+	}
+	runes := []rune(text)
+	chunks := make([]string, 0, (len(runes)+chunkSize-1)/chunkSize)
+	for start := 0; start < len(runes); start += chunkSize {
+		end := start + chunkSize
+		if end > len(runes) {
+			end = len(runes)
+		}
+		chunks = append(chunks, string(runes[start:end]))
+	}
+	return chunks
+}
+
+func newClaudeWebSearchToolUseID() string {
+	return fmt.Sprintf("srvtoolu_%d", time.Now().UnixNano())
+}
diff --git a/sdk/cliproxy/antigravity_models.go b/sdk/cliproxy/antigravity_models.go
new file mode 100644
index 00000000..11f7c408
--- /dev/null
+++ b/sdk/cliproxy/antigravity_models.go
@@ -0,0 +1,150 @@
+package cliproxy
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/misc"
+	coreauth "github.com/router-for-me/CLIProxyAPI/v7/sdk/cliproxy/auth"
+	"github.com/router-for-me/CLIProxyAPI/v7/sdk/proxyutil"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	antigravityModelBaseURLDaily = "https://daily-cloudcode-pa.googleapis.com"
+	antigravityModelBaseURLProd  = "https://cloudcode-pa.googleapis.com"
+	antigravityModelsPath        = "/v1internal:fetchAvailableModels"
+)
+
+type antigravityFetchAvailableModelsResponse struct {
+	WebSearchModelIDs []string `json:"webSearchModelIds"`
+}
+
+type antigravityModelCapabilityHints struct {
+	WebSearchModelIDs map[string]struct{}
+}
+
+func (s *Service) fetchAntigravityModelCapabilityHintsForAuth(ctx context.Context, auth *coreauth.Auth) antigravityModelCapabilityHints {
+	if auth == nil || auth.Metadata == nil {
+		return antigravityModelCapabilityHints{}
+	}
+	accessToken, _ := auth.Metadata["access_token"].(string)
+	accessToken = strings.TrimSpace(accessToken)
+	if accessToken == "" {
+		return antigravityModelCapabilityHints{}
+	}
+
+	client := &http.Client{}
+	if transport, _, errProxy := proxyutil.BuildHTTPTransport(s.antigravityModelFetchProxyURL(auth)); errProxy == nil && transport != nil {
+		client.Transport = transport
+	}
+
+	for _, baseURL := range antigravityModelBaseURLs(auth) {
+		req, errReq := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(baseURL, "/")+antigravityModelsPath, strings.NewReader(`{}`))
+		if errReq != nil {
+			continue
+		}
+		req.Close = true
+		req.Header.Set("Content-Type", "application/json")
+		req.Header.Set("Authorization", "Bearer "+accessToken)
+		req.Header.Set("User-Agent", misc.AntigravityUserAgent())
+
+		resp, errDo := client.Do(req)
+		if errDo != nil {
+			continue
+		}
+		body, errRead := io.ReadAll(resp.Body)
+		if errClose := resp.Body.Close(); errClose != nil {
+			log.Debugf("antigravity model fetch: close response body: %v", errClose)
+		}
+		if errRead != nil {
+			continue
+		}
+		if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+			continue
+		}
+		hints := parseAntigravityModelCapabilityHints(body)
+		if len(hints.WebSearchModelIDs) > 0 {
+			return hints
+		}
+	}
+	return antigravityModelCapabilityHints{}
+}
+
+func (s *Service) antigravityModelFetchProxyURL(auth *coreauth.Auth) string {
+	if auth != nil {
+		if proxyURL := strings.TrimSpace(auth.ProxyURL); proxyURL != "" {
+			return proxyURL
+		}
+	}
+	if s != nil && s.cfg != nil {
+		return strings.TrimSpace(s.cfg.ProxyURL)
+	}
+	return ""
+}
+
+func antigravityModelBaseURLs(auth *coreauth.Auth) []string {
+	if baseURL := resolveAntigravityModelBaseURL(auth); baseURL != "" {
+		return []string{baseURL}
+	}
+	return []string{antigravityModelBaseURLDaily, antigravityModelBaseURLProd}
+}
+
+func resolveAntigravityModelBaseURL(auth *coreauth.Auth) string {
+	if auth == nil {
+		return ""
+	}
+	if auth.Attributes != nil {
+		if value := strings.TrimSpace(auth.Attributes["base_url"]); value != "" {
+			return strings.TrimRight(value, "/")
+		}
+	}
+	if auth.Metadata != nil {
+		if value, ok := auth.Metadata["base_url"].(string); ok {
+			value = strings.TrimSpace(value)
+			if value != "" {
+				return strings.TrimRight(value, "/")
+			}
+		}
+	}
+	return ""
+}
+
+func parseAntigravityModelCapabilityHints(body []byte) antigravityModelCapabilityHints {
+	var parsed antigravityFetchAvailableModelsResponse
+	if err := json.Unmarshal(body, &parsed); err != nil {
+		return antigravityModelCapabilityHints{}
+	}
+	webSearchModels := make(map[string]struct{}, len(parsed.WebSearchModelIDs))
+	for _, modelID := range parsed.WebSearchModelIDs {
+		modelID = normalizeAntigravityFetchedModelID(modelID)
+		if modelID != "" {
+			webSearchModels[modelID] = struct{}{}
+		}
+	}
+	return antigravityModelCapabilityHints{WebSearchModelIDs: webSearchModels}
+}
+
+func applyAntigravityFetchedModelCapabilities(models []*ModelInfo, hints antigravityModelCapabilityHints) []*ModelInfo {
+	if len(models) == 0 || len(hints.WebSearchModelIDs) == 0 {
+		return models
+	}
+
+	for _, model := range models {
+		if model == nil {
+			continue
+		}
+		modelID := normalizeAntigravityFetchedModelID(model.ID)
+		if _, ok := hints.WebSearchModelIDs[modelID]; ok {
+			model.SupportsWebSearch = true
+		}
+	}
+	return models
+}
+
+func normalizeAntigravityFetchedModelID(modelID string) string {
+	return strings.ToLower(strings.TrimSpace(modelID))
+}
diff --git a/sdk/cliproxy/service.go b/sdk/cliproxy/service.go
index d3cd9a4b..bedbffb8 100644
--- a/sdk/cliproxy/service.go
+++ b/sdk/cliproxy/service.go
@@ -1782,6 +1782,7 @@ func (s *Service) registerModelsForAuth(ctx context.Context, a *coreauth.Auth) {
 		models = applyExcludedModels(models, excluded)
 	case "antigravity":
 		models = registry.GetAntigravityModels()
+		models = applyAntigravityFetchedModelCapabilities(models, s.fetchAntigravityModelCapabilityHintsForAuth(ctx, a))
 		models = applyExcludedModels(models, excluded)
 	case "claude":
 		models = registry.GetClaudeModels()
diff --git a/sdk/cliproxy/service_excluded_models_test.go b/sdk/cliproxy/service_excluded_models_test.go
index baaa60f6..fd44436f 100644
--- a/sdk/cliproxy/service_excluded_models_test.go
+++ b/sdk/cliproxy/service_excluded_models_test.go
@@ -2,6 +2,8 @@ package cliproxy
 
 import (
 	"context"
+	"net/http"
+	"net/http/httptest"
 	"strings"
 	"testing"
 
@@ -133,3 +135,106 @@ func TestRegisterModelsForAuth_OpenAICompatibilityImageModelType(t *testing.T) {
 		t.Fatal("expected chat model to keep default thinking support")
 	}
 }
+
+func TestRegisterModelsForAuth_AntigravityFetchesWebSearchCapability(t *testing.T) {
+	var sawFetch bool
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != antigravityModelsPath {
+			t.Fatalf("path = %q, want %s", r.URL.Path, antigravityModelsPath)
+		}
+		if got := r.Header.Get("Authorization"); got != "Bearer token" {
+			t.Fatalf("Authorization = %q, want bearer token", got)
+		}
+		sawFetch = true
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+				"models": {
+					"gemini-3.1-flash-lite": {
+						"displayName": "Gemini 3.1 Flash Lite",
+						"maxTokens": 1,
+						"maxOutputTokens": 2
+					},
+					"fetched-only-search-model": {
+						"displayName": "Fetched Only Search Model"
+					}
+				},
+				"webSearchModelIds": ["gemini-3.1-flash-lite", "fetched-only-search-model"]
+			}`))
+	}))
+	defer server.Close()
+
+	service := &Service{cfg: &config.Config{}}
+	auth := &coreauth.Auth{
+		ID:       "auth-antigravity-fetch-models",
+		Provider: "antigravity",
+		Status:   coreauth.StatusActive,
+		Attributes: map[string]string{
+			"base_url": server.URL,
+		},
+		Metadata: map[string]any{
+			"access_token": "token",
+		},
+	}
+
+	registry := internalregistry.GetGlobalRegistry()
+	registry.UnregisterClient(auth.ID)
+	t.Cleanup(func() {
+		registry.UnregisterClient(auth.ID)
+	})
+
+	service.registerModelsForAuth(context.Background(), auth)
+	if !sawFetch {
+		t.Fatal("expected fetchAvailableModels request")
+	}
+
+	models := registry.GetModelsForClient(auth.ID)
+	staticModels := internalregistry.GetAntigravityModels()
+	staticByID := make(map[string]*internalregistry.ModelInfo, len(staticModels))
+	for _, model := range staticModels {
+		if model != nil {
+			staticByID[model.ID] = model
+		}
+	}
+
+	var webSearchModel, agentModel, staticOnlyModel, fetchedOnlyModel *internalregistry.ModelInfo
+	for _, model := range models {
+		if model == nil {
+			continue
+		}
+		switch strings.TrimSpace(model.ID) {
+		case "gemini-3.1-flash-lite":
+			webSearchModel = model
+		case "gemini-3-flash-agent":
+			agentModel = model
+		case "gpt-oss-120b-medium":
+			staticOnlyModel = model
+		case "fetched-only-search-model":
+			fetchedOnlyModel = model
+		}
+	}
+	if webSearchModel == nil {
+		t.Fatal("expected gemini-3.1-flash-lite to be registered")
+	}
+	if !webSearchModel.SupportsWebSearch {
+		t.Fatal("expected gemini-3.1-flash-lite to support web search")
+	}
+	staticWebSearchModel := staticByID["gemini-3.1-flash-lite"]
+	if staticWebSearchModel == nil {
+		t.Fatal("expected static gemini-3.1-flash-lite definition")
+	}
+	if webSearchModel.ContextLength != staticWebSearchModel.ContextLength || webSearchModel.MaxCompletionTokens != staticWebSearchModel.MaxCompletionTokens {
+		t.Fatalf("static token limits should be preserved, got=%#v static=%#v", webSearchModel, staticWebSearchModel)
+	}
+	if agentModel == nil {
+		t.Fatal("expected gemini-3-flash-agent to be registered")
+	}
+	if agentModel.SupportsWebSearch {
+		t.Fatal("gemini-3-flash-agent should not support web search")
+	}
+	if staticOnlyModel == nil {
+		t.Fatal("expected static-only Antigravity model to remain registered")
+	}
+	if fetchedOnlyModel != nil {
+		t.Fatalf("fetched-only model should not be registered: %#v", fetchedOnlyModel)
+	}
+}