diff --git a/backend/internal/pkg/antigravity/gemini_types.go b/backend/internal/pkg/antigravity/gemini_types.go
index 4fd7882adc..599119618e 100644
--- a/backend/internal/pkg/antigravity/gemini_types.go
+++ b/backend/internal/pkg/antigravity/gemini_types.go
@@ -86,8 +86,12 @@ type GeminiThinkingConfig struct {
 type GeminiToolDeclaration struct {
 	FunctionDeclarations []GeminiFunctionDecl `json:"functionDeclarations,omitempty"`
 	GoogleSearch         *GeminiGoogleSearch  `json:"googleSearch,omitempty"`
+	CodeExecution        *GeminiCodeExecution `json:"codeExecution,omitempty"`
 }
 
+// GeminiCodeExecution enables Gemini's built-in code execution tool.
+type GeminiCodeExecution struct{}
+
 // GeminiFunctionDecl Gemini 函数声明
 type GeminiFunctionDecl struct {
 	Name        string         `json:"name"`
diff --git a/backend/internal/pkg/antigravity/request_transformer.go b/backend/internal/pkg/antigravity/request_transformer.go
index 9da3cc33a2..819db987f0 100644
--- a/backend/internal/pkg/antigravity/request_transformer.go
+++ b/backend/internal/pkg/antigravity/request_transformer.go
@@ -710,6 +710,10 @@ func isWebSearchTool(tool ClaudeTool) bool {
 	}
 }
 
+func isCodeExecutionTool(tool ClaudeTool) bool {
+	return strings.TrimSpace(tool.Type) == "code_execution"
+}
+
 // hasMixedToolInvocations 判断构建后的工具声明是否同时包含函数声明与内置工具
 // （googleSearch）。仅在两者并存时需要开启 includeServerSideToolInvocations。
 func hasMixedToolInvocations(declarations []GeminiToolDeclaration) bool {
@@ -718,7 +722,7 @@ func hasMixedToolInvocations(declarations []GeminiToolDeclaration) bool {
 		if len(d.FunctionDeclarations) > 0 {
 			hasFunc = true
 		}
-		if d.GoogleSearch != nil {
+		if d.GoogleSearch != nil || d.CodeExecution != nil {
 			hasBuiltin = true
 		}
 	}
@@ -732,11 +736,18 @@ func buildTools(tools []ClaudeTool) []GeminiToolDeclaration {
 	}
 
 	hasWebSearch := hasWebSearchTool(tools)
+	hasCodeExecution := false
+	for _, tool := range tools {
+		if isCodeExecutionTool(tool) {
+			hasCodeExecution = true
+			break
+		}
+	}
 
 	// 普通工具
 	var funcDecls []GeminiFunctionDecl
 	for _, tool := range tools {
-		if isWebSearchTool(tool) {
+		if isWebSearchTool(tool) || isCodeExecutionTool(tool) {
 			continue
 		}
 		// 跳过无效工具名称
@@ -800,6 +811,11 @@ func buildTools(tools []ClaudeTool) []GeminiToolDeclaration {
 			},
 		})
 	}
+	if hasCodeExecution {
+		declarations = append(declarations, GeminiToolDeclaration{
+			CodeExecution: &GeminiCodeExecution{},
+		})
+	}
 	if len(declarations) == 0 {
 		return nil
 	}
diff --git a/backend/internal/pkg/apicompat/chatcompletions_to_responses.go b/backend/internal/pkg/apicompat/chatcompletions_to_responses.go
index 384b58495b..f72b5faf6d 100644
--- a/backend/internal/pkg/apicompat/chatcompletions_to_responses.go
+++ b/backend/internal/pkg/apicompat/chatcompletions_to_responses.go
@@ -428,7 +428,8 @@ func convertChatToolsToResponses(tools []ChatTool, functions []ChatFunction) []R
 	var out []ResponsesTool
 
 	for _, t := range tools {
-		if strings.EqualFold(strings.TrimSpace(t.Type), "x_search") {
+		toolType := strings.ToLower(strings.TrimSpace(t.Type))
+		if toolType == "x_search" {
 			out = append(out, ResponsesTool{
 				Type:                     "x_search",
 				AllowedXHandles:          t.AllowedXHandles,
@@ -440,6 +441,10 @@ func convertChatToolsToResponses(tools []ChatTool, functions []ChatFunction) []R
 			})
 			continue
 		}
+		if toolType == "web_search" || toolType == "code_execution" {
+			out = append(out, ResponsesTool{Type: toolType})
+			continue
+		}
 		if t.Type != "function" || t.Function == nil {
 			continue
 		}
diff --git a/backend/internal/pkg/apicompat/chatcompletions_x_search_test.go b/backend/internal/pkg/apicompat/chatcompletions_x_search_test.go
index 2ffbea2a3b..79230edecd 100644
--- a/backend/internal/pkg/apicompat/chatcompletions_x_search_test.go
+++ b/backend/internal/pkg/apicompat/chatcompletions_x_search_test.go
@@ -41,6 +41,28 @@ func TestChatCompletionsToResponsesPreservesXSearchTool(t *testing.T) {
 	require.JSONEq(t, `{"type":"x_search"}`, string(resp.ToolChoice))
 }
 
+func TestChatCompletionsToResponsesPreservesSupportedBuiltInTools(t *testing.T) {
+	req := &ChatCompletionsRequest{
+		Model:    "claude-opus-4-6-thinking",
+		Messages: []ChatMessage{{Role: "user", Content: json.RawMessage(`"hello"`)}},
+		Tools: []ChatTool{
+			{Type: "function", Function: &ChatFunction{Name: "read_file", Parameters: json.RawMessage(`{"type":"object"}`)}},
+			{Type: "web_search"},
+			{Type: "code_execution"},
+			{Type: "unsupported_builtin"},
+			{Type: "function"},
+		},
+	}
+
+	resp, err := ChatCompletionsToResponses(req)
+	require.NoError(t, err)
+	require.Len(t, resp.Tools, 3)
+	require.Equal(t, "function", resp.Tools[0].Type)
+	require.Equal(t, "read_file", resp.Tools[0].Name)
+	require.Equal(t, "web_search", resp.Tools[1].Type)
+	require.Equal(t, "code_execution", resp.Tools[2].Type)
+}
+
 func TestResponsesToChatCompletionsPreservesXSearchTool(t *testing.T) {
 	enabled := true
 	req := &ResponsesRequest{
diff --git a/backend/internal/pkg/apicompat/types.go b/backend/internal/pkg/apicompat/types.go
index 3b4b618e1f..3a9d0a8ff2 100644
--- a/backend/internal/pkg/apicompat/types.go
+++ b/backend/internal/pkg/apicompat/types.go
@@ -716,7 +716,7 @@ type ChatFile struct {
 
 // ChatTool describes a tool available to the model.
 type ChatTool struct {
-	Type     string        `json:"type"` // "function" | "x_search"
+	Type     string        `json:"type"` // "function" | "web_search" | "code_execution" | "x_search"
 	Function *ChatFunction `json:"function,omitempty"`
 
 	// type=x_search
diff --git a/backend/internal/service/antigravity_gateway_compat_test.go b/backend/internal/service/antigravity_gateway_compat_test.go
index a92b1654c2..eb4f67ab6e 100644
--- a/backend/internal/service/antigravity_gateway_compat_test.go
+++ b/backend/internal/service/antigravity_gateway_compat_test.go
@@ -89,8 +89,9 @@ func newAntigravityCompatAccount(accountType string) *Account {
 			"access_token": "stale-account-token",
 			"project_id":   "project-3757",
 			"model_mapping": map[string]any{
-				"gemini-3.1-pro-high": "gemini-3.1-pro-high",
-				"claude-sonnet-4-5":   "claude-sonnet-4-5",
+				"gemini-3.1-pro-high":      "gemini-3.1-pro-high",
+				"claude-sonnet-4-5":        "claude-sonnet-4-5",
+				"claude-opus-4-6-thinking": "claude-opus-4-6-thinking",
 			},
 		},
 	}
@@ -269,6 +270,35 @@ func TestBuildAntigravityCompatGeminiBody_ConfiguresMixedToolInvocations(t *test
 	}
 }
 
+func TestAntigravityCompatChatMixedBuiltInToolsEnableServerSideInvocations(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	upstream := &queuedHTTPUpstreamStub{responses: []*http.Response{antigravityCompatSuccessResponse()}}
+	svc := newAntigravityCompatService(config.GatewayConfig{MaxLineSize: defaultMaxLineSize}, upstream)
+	body := []byte(`{
+		"model":"claude-opus-4-6-thinking",
+		"messages":[{"role":"user","content":"hello"}],
+		"stream":true,
+		"tools":[
+			{"type":"function","function":{"name":"read_file","parameters":{"type":"object","properties":{"path":{"type":"string"}}}}},
+			{"type":"function","function":{"name":"terminal","parameters":{"type":"object","properties":{"command":{"type":"string"}}}}},
+			{"type":"web_search"},
+			{"type":"code_execution"}
+		]
+	}`)
+	c, _ := newAntigravityCompatContext(http.MethodPost, "/v1/chat/completions", body)
+
+	result, err := svc.ForwardAsChatCompletions(context.Background(), c, newAntigravityCompatAccount(AccountTypeOAuth), body, nil)
+
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Len(t, upstream.requestBodies, 1)
+	requestBody := upstream.requestBodies[0]
+	require.True(t, gjson.GetBytes(requestBody, "request.toolConfig.includeServerSideToolInvocations").Bool())
+	require.Len(t, gjson.GetBytes(requestBody, "request.tools.0.functionDeclarations").Array(), 2)
+	require.True(t, gjson.GetBytes(requestBody, "request.tools.1.googleSearch").Exists())
+	require.True(t, gjson.GetBytes(requestBody, "request.tools.2.codeExecution").Exists())
+}
+
 func TestAntigravityCompatPreservesChatTokenLimit(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	tests := []struct {