diff --git a/extensions/google/cli-backend.ts b/extensions/google/cli-backend.ts
index 14c20e2ba25..2718827e1ca 100644
--- a/extensions/google/cli-backend.ts
+++ b/extensions/google/cli-backend.ts
@@ -78,8 +78,11 @@ type GeminiApiKeyCredential = GeminiAuthProfileCredential & {
 type GeminiCliAuthHomeContext = {
   agentDir?: string;
   authProfileId?: string;
+  systemSettingsPath?: string;
 };
 
+type GeminiCliAuthSelectedType = "oauth-personal" | "gemini-api-key";
+
 function throwUnsupportedGeminiCredential(credential: GeminiAuthProfileCredential): never {
   if (credential.provider === VERCEL_AI_GATEWAY_PROVIDER_ID) {
     throw new Error(
@@ -195,6 +198,55 @@ function resolveGeminiCliProfileHome(ctx: GeminiCliAuthHomeContext): {
   return { home, geminiDir: path.join(home, ".gemini") };
 }
 
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return value !== null && typeof value === "object" && !Array.isArray(value);
+}
+
+async function readGeminiCliJsonObject(
+  filePath: string | undefined,
+): Promise<Record<string, unknown>> {
+  const normalized = normalizeString(filePath);
+  if (!normalized) {
+    return {};
+  }
+  try {
+    const parsed = JSON.parse(await fs.readFile(normalized, "utf8")) as unknown;
+    if (!isRecord(parsed)) {
+      throw new Error(`Gemini CLI system settings must be a JSON object: ${normalized}`);
+    }
+    return { ...parsed };
+  } catch (error) {
+    if (
+      error &&
+      typeof error === "object" &&
+      "code" in error &&
+      (error as { code?: unknown }).code === "ENOENT"
+    ) {
+      return {};
+    }
+    throw error;
+  }
+}
+
+function buildGeminiCliAuthSettings(
+  selectedType: GeminiCliAuthSelectedType,
+): Record<string, unknown> {
+  return { security: { auth: { selectedType } } };
+}
+
+async function buildGeminiCliSystemSettings(
+  ctx: GeminiCliAuthHomeContext,
+  selectedType: GeminiCliAuthSelectedType,
+): Promise<Record<string, unknown>> {
+  const base = await readGeminiCliJsonObject(ctx.systemSettingsPath);
+  const security = isRecord(base.security) ? { ...base.security } : {};
+  security.auth = { selectedType };
+  return {
+    ...base,
+    security,
+  };
+}
+
 async function writeGeminiCliJson(filePath: string, value: unknown): Promise<void> {
   await fs.writeFile(filePath, `${JSON.stringify(value, null, 2)}\n`, {
     encoding: "utf8",
@@ -205,20 +257,25 @@ async function writeGeminiCliJson(filePath: string, value: unknown): Promise<voi
 
 async function prepareGeminiCliProfileHome(
   ctx: GeminiCliAuthHomeContext,
-  settings: unknown,
+  selectedType: GeminiCliAuthSelectedType,
 ): Promise<{
   home: string;
   geminiDir: string;
+  systemSettingsPath: string;
 }> {
   const { home, geminiDir } = resolveGeminiCliProfileHome(ctx);
   await fs.mkdir(geminiDir, { recursive: true, mode: 0o700 });
   await fs.chmod(home, 0o700);
   await fs.chmod(geminiDir, 0o700);
+  const settings = buildGeminiCliAuthSettings(selectedType);
+  const systemSettings = await buildGeminiCliSystemSettings(ctx, selectedType);
+  const systemSettingsPath = path.join(home, "system-settings.json");
   await Promise.all([
     writeGeminiCliJson(path.join(geminiDir, "settings.json"), settings),
     writeGeminiCliJson(path.join(home, "settings.json"), settings),
+    writeGeminiCliJson(systemSettingsPath, systemSettings),
   ]);
-  return { home, geminiDir };
+  return { home, geminiDir, systemSettingsPath };
 }
 
 async function clearGeminiCliCachedCredentials(geminiDir: string): Promise<void> {
@@ -248,9 +305,10 @@ async function prepareGeminiCliOAuthHome(
     return null;
   }
 
-  const { home, geminiDir } = await prepareGeminiCliProfileHome(ctx, {
-    security: { auth: { selectedType: "oauth-personal" } },
-  });
+  const { home, geminiDir, systemSettingsPath } = await prepareGeminiCliProfileHome(
+    ctx,
+    "oauth-personal",
+  );
   await clearGeminiCliCachedCredentials(geminiDir);
   const idToken = normalizeString(oauth.idToken);
   const oauthCreds: Record<string, string | number> = {
@@ -268,6 +326,7 @@ async function prepareGeminiCliOAuthHome(
   return {
     env: {
       GEMINI_CLI_HOME: home,
+      GEMINI_CLI_SYSTEM_SETTINGS_PATH: systemSettingsPath,
       GEMINI_FORCE_FILE_STORAGE: "true",
       ...buildGeminiCliProjectEnv(oauth.projectId),
     },
@@ -284,9 +343,10 @@ async function prepareGeminiCliApiKeyHome(
     return null;
   }
 
-  const { home, geminiDir } = await prepareGeminiCliProfileHome(ctx, {
-    security: { auth: { selectedType: "gemini-api-key" } },
-  });
+  const { home, geminiDir, systemSettingsPath } = await prepareGeminiCliProfileHome(
+    ctx,
+    "gemini-api-key",
+  );
   await Promise.all([
     fs.rm(path.join(geminiDir, "oauth_creds.json"), { force: true }),
     clearGeminiCliCachedCredentials(geminiDir),
@@ -294,6 +354,7 @@ async function prepareGeminiCliApiKeyHome(
   return {
     env: {
       GEMINI_CLI_HOME: home,
+      GEMINI_CLI_SYSTEM_SETTINGS_PATH: systemSettingsPath,
       GEMINI_FORCE_FILE_STORAGE: "true",
       GEMINI_API_KEY: apiKey.key,
     },
@@ -339,6 +400,8 @@ export function buildGoogleGeminiCliBackend(): CliBackendPlugin {
         {
           agentDir: ctx.agentDir,
           authProfileId: ctx.authProfileId,
+          systemSettingsPath: (ctx as typeof ctx & { env?: Record<string, string> }).env
+            ?.GEMINI_CLI_SYSTEM_SETTINGS_PATH,
         },
         (ctx as typeof ctx & { authCredential?: GeminiAuthProfileCredential }).authCredential,
       ),
diff --git a/extensions/google/setup-api.test.ts b/extensions/google/setup-api.test.ts
index e08890cd9f3..cfaa085c1b5 100644
--- a/extensions/google/setup-api.test.ts
+++ b/extensions/google/setup-api.test.ts
@@ -10,6 +10,7 @@ import setupEntry from "./setup-api.js";
 type GeminiPrepareContext = Parameters<
   NonNullable<ReturnType<typeof buildGoogleGeminiCliBackend>["prepareExecution"]>
 >[0] & {
+  env?: Record<string, string>;
   authCredential?: {
     type: "api_key" | "oauth" | "token";
     provider: string;
@@ -98,10 +99,24 @@ describe("google gemini cli backend auth bridge", () => {
 
     try {
       const context = buildGeminiOAuthPrepareContext(workspaceDir);
+      const inheritedSettingsPath = path.join(workspaceDir, "generated-mcp-settings.json");
+      await fs.writeFile(
+        inheritedSettingsPath,
+        `${JSON.stringify({
+          security: { auth: { selectedType: "vertex-ai" } },
+          mcp: { allowed: ["openclaw"] },
+          mcpServers: { openclaw: { url: "http://127.0.0.1:23119/mcp" } },
+        })}\n`,
+        "utf8",
+      );
+      context.env = { GEMINI_CLI_SYSTEM_SETTINGS_PATH: inheritedSettingsPath };
       const prepared = await backend.prepareExecution?.(context);
 
       home = prepared?.env?.GEMINI_CLI_HOME;
+      const systemSettingsPath = prepared?.env?.GEMINI_CLI_SYSTEM_SETTINGS_PATH;
       expect(home).toBeTruthy();
+      expect(systemSettingsPath).toBeTruthy();
+      expect(systemSettingsPath).not.toBe(inheritedSettingsPath);
       expect(prepared?.env?.GEMINI_FORCE_FILE_STORAGE).toBe("true");
       expect(prepared?.env?.GOOGLE_CLOUD_PROJECT).toBe("profile-project");
       expect(prepared?.env?.GOOGLE_CLOUD_PROJECT_ID).toBe("profile-project");
@@ -126,6 +141,12 @@ describe("google gemini cli backend auth bridge", () => {
         security: { auth: { selectedType: "oauth-personal" } },
       });
       expect(JSON.parse(rootSettingsRaw)).toEqual(JSON.parse(nestedSettingsRaw));
+      const systemSettingsRaw = await fs.readFile(systemSettingsPath ?? "", "utf8");
+      expect(JSON.parse(systemSettingsRaw)).toEqual({
+        security: { auth: { selectedType: "oauth-personal" } },
+        mcp: { allowed: ["openclaw"] },
+        mcpServers: { openclaw: { url: "http://127.0.0.1:23119/mcp" } },
+      });
 
       const sessionMarker = path.join(home ?? "", ".gemini", "session-state.json");
       await fs.writeFile(sessionMarker, '{"keep":true}\n', "utf8");
diff --git a/src/agents/cli-runner/prepare.test.ts b/src/agents/cli-runner/prepare.test.ts
index a70e8061df7..e6442c4f0ec 100644
--- a/src/agents/cli-runner/prepare.test.ts
+++ b/src/agents/cli-runner/prepare.test.ts
@@ -670,6 +670,85 @@ describe("shouldSkipLocalCliCredentialEpoch", () => {
     }
   });
 
+  it("lets Gemini CLI preparation override generated MCP system settings auth", async () => {
+    const { dir, sessionFile } = createSessionFile();
+    const profileSystemSettingsPath = path.join(dir, "profile-system-settings.json");
+    const getActiveMcpLoopbackRuntime = vi.fn(() => ({
+      port: 31783,
+      ownerToken: "loopback-owner-token",
+      nonOwnerToken: "loopback-non-owner-token",
+    }));
+    const prepareExecution = vi.fn(async () => ({
+      env: {
+        GEMINI_CLI_SYSTEM_SETTINGS_PATH: profileSystemSettingsPath,
+      },
+    }));
+    cliBackendsTesting.setDepsForTest({
+      resolvePluginSetupCliBackend: () => undefined,
+      resolveRuntimeCliBackends: () => [
+        {
+          id: "google-gemini-cli",
+          pluginId: "google",
+          bundleMcp: true,
+          bundleMcpMode: "gemini-system-settings",
+          prepareExecution,
+          config: {
+            command: "gemini",
+            args: ["--prompt", "{prompt}"],
+            output: "json",
+            input: "arg",
+            sessionMode: "existing",
+          },
+        },
+      ],
+    });
+    setCliRunnerPrepareTestDeps({
+      getActiveMcpLoopbackRuntime,
+      ensureMcpLoopbackServer: vi.fn(createTestMcpLoopbackServer),
+      createMcpLoopbackServerConfig: vi.fn(createTestMcpLoopbackServerConfig),
+      resolveMcpLoopbackBearerToken: vi.fn(() => "loopback-token"),
+      resolveMcpLoopbackScopedTools: vi.fn(() => ({ agentId: "main", tools: [] })),
+    });
+
+    let cleanup: (() => Promise<void>) | undefined;
+    try {
+      const context = await prepareCliRunContext({
+        sessionId: "session-test",
+        sessionKey: "agent:main:main",
+        sessionFile,
+        workspaceDir: dir,
+        prompt: "latest ask",
+        provider: "google-gemini-cli",
+        model: "gemini-3.1-pro-preview",
+        timeoutMs: 1_000,
+        runId: "run-test-gemini-mcp-system-settings",
+        config: {},
+      });
+      cleanup = context.preparedBackend.cleanup;
+
+      const prepareExecutionArg = prepareExecution.mock.calls[0]?.[0] as
+        | { env?: Record<string, string> }
+        | undefined;
+      const generatedSystemSettingsPath = prepareExecutionArg?.env?.GEMINI_CLI_SYSTEM_SETTINGS_PATH;
+      expect(typeof generatedSystemSettingsPath).toBe("string");
+      expect(generatedSystemSettingsPath).not.toBe(profileSystemSettingsPath);
+      const generatedSettings = JSON.parse(
+        fs.readFileSync(generatedSystemSettingsPath ?? "", "utf8"),
+      ) as {
+        mcp?: { allowed?: string[] };
+        mcpServers?: Record<string, { url?: string }>;
+      };
+      expect(generatedSettings.mcp?.allowed).toEqual(["openclaw"]);
+      expect(generatedSettings.mcpServers?.openclaw?.url).toBe("http://127.0.0.1:31783/mcp");
+      expect(context.preparedBackend.env?.GEMINI_CLI_SYSTEM_SETTINGS_PATH).toBe(
+        profileSystemSettingsPath,
+      );
+    } finally {
+      await cleanup?.();
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
   it("prepares side questions without agent-turn context, tools, hooks, or reusable sessions", async () => {
     const { dir, sessionFile } = createSessionFile();
     appendTranscriptEntry(sessionFile, {
diff --git a/src/agents/cli-runner/prepare.ts b/src/agents/cli-runner/prepare.ts
index 0287aa3bad3..0e71ab752a9 100644
--- a/src/agents/cli-runner/prepare.ts
+++ b/src/agents/cli-runner/prepare.ts
@@ -474,6 +474,7 @@ export async function prepareCliRunContext(
     modelId,
     authProfileId: effectiveAuthProfileId,
     executionMode,
+    env: preparedBackend.env,
   } as Parameters<NonNullable<typeof backendResolved.prepareExecution>>[0];
   const preparedExecution = await backendResolved.prepareExecution?.(
     (backendResolved.id === "google-gemini-cli"