feat(core): use experiment flags for default fetch timeouts

Replaces hardcoded fetch timeouts in `undici`'s Agent and ProxyAgent with
newly defined experiment flags `DEFAULT_REQUEST_TIMEOUT` and
`DEFAULT_TOTAL_REQUEST_TIMEOUT`. This allows for remote configuration
of request timeouts.

- Added `DEFAULT_REQUEST_TIMEOUT` and `DEFAULT_TOTAL_REQUEST_TIMEOUT` to `ExperimentFlags`.
- Updated `fetch.ts` to use `DEFAULT_REQUEST_TIMEOUT` for headers and body timeouts.
- Added unit tests to verify `setGlobalProxy` correctly applies the timeout flags.

Author: yunaseoul

packages/cli/src/test-utils/mockConfig.ts

@@ -136,6 +136,7 @@ export const createMockConfig = (overrides: Partial<Config> = {}): Config =>
     getRetryFetchErrors: vi.fn().mockReturnValue(true),
     getEnableShellOutputEfficiency: vi.fn().mockReturnValue(true),
     getShellToolInactivityTimeout: vi.fn().mockReturnValue(300000),
+    getRequestTimeoutMs: vi.fn().mockReturnValue(undefined),
     getShellExecutionConfig: vi.fn().mockReturnValue({
       sandboxManager: new NoopSandboxManager(),
       sanitizationConfig: {

packages/core/src/code_assist/experiments/flagNames.ts

@@ -19,6 +19,7 @@ export const ExperimentFlags = {
   GEMINI_3_1_PRO_LAUNCHED: 45760185,
   PRO_MODEL_NO_ACCESS: 45768879,
   GEMINI_3_1_FLASH_LITE_LAUNCHED: 45771641,
+  DEFAULT_REQUEST_TIMEOUT: 45773134,
 } as const;
 
 export type ExperimentFlagName =

packages/core/src/config/config.test.ts

@@ -644,6 +644,58 @@ describe('Server Config (config.ts)', () => {
         },
       );
     });
+
+    describe('getRequestTimeoutMs', () => {
+      it('should return undefined if the flag is not set', () => {
+        const config = new Config(baseParams);
+        expect(config.getRequestTimeoutMs()).toBeUndefined();
+      });
+
+      it('should return timeout in milliseconds if flag is set', () => {
+        const config = new Config({
+          ...baseParams,
+          experiments: {
+            flags: {
+              [ExperimentFlags.DEFAULT_REQUEST_TIMEOUT]: {
+                intValue: '30',
+              },
+            },
+            experimentIds: [],
+          },
+        } as unknown as ConfigParameters);
+        expect(config.getRequestTimeoutMs()).toBe(30000);
+      });
+
+      it('should return undefined if intValue is not a valid integer', () => {
+        const config = new Config({
+          ...baseParams,
+          experiments: {
+            flags: {
+              [ExperimentFlags.DEFAULT_REQUEST_TIMEOUT]: {
+                intValue: 'abc',
+              },
+            },
+            experimentIds: [],
+          },
+        } as unknown as ConfigParameters);
+        expect(config.getRequestTimeoutMs()).toBeUndefined();
+      });
+
+      it('should return undefined if intValue is negative', () => {
+        const config = new Config({
+          ...baseParams,
+          experiments: {
+            flags: {
+              [ExperimentFlags.DEFAULT_REQUEST_TIMEOUT]: {
+                intValue: '-10',
+              },
+            },
+            experimentIds: [],
+          },
+        } as unknown as ConfigParameters);
+        expect(config.getRequestTimeoutMs()).toBeUndefined();
+      });
+    });
   });
 
   describe('refreshAuth', () => {

packages/core/src/config/config.ts

@@ -160,7 +160,7 @@ import {
 } from '../code_assist/experiments/experiments.js';
 import { AgentRegistry } from '../agents/registry.js';
 import { AcknowledgedAgentsService } from '../agents/acknowledgedAgents.js';
-import { setGlobalProxy } from '../utils/fetch.js';
+import { setGlobalProxy, updateGlobalFetchTimeouts } from '../utils/fetch.js';
 import { SubagentTool } from '../agents/subagent-tool.js';
 import { ExperimentFlags } from '../code_assist/experiments/flagNames.js';
 import { debugLogger } from '../utils/debugLogger.js';
@@ -1584,6 +1584,11 @@ export class Config implements McpContext, AgentLoopContext {
     // Fetch admin controls
     const experiments = await this.experimentsPromise;
 
+    const requestTimeoutMs = this.getRequestTimeoutMs();
+    if (requestTimeoutMs !== undefined) {
+      updateGlobalFetchTimeouts(requestTimeoutMs);
+    }
+
     const adminControlsEnabled =
       experiments?.flags[ExperimentFlags.ENABLE_ADMIN_CONTROLS]?.boolValue ??
       false;
@@ -3149,6 +3154,21 @@ export class Config implements McpContext, AgentLoopContext {
     );
   }
 
+  /**
+   * Returns the configured default request timeout in milliseconds.
+   */
+  getRequestTimeoutMs(): number | undefined {
+    const flag =
+      this.experiments?.flags?.[ExperimentFlags.DEFAULT_REQUEST_TIMEOUT];
+    if (flag?.intValue !== undefined) {
+      const seconds = parseInt(flag.intValue, 10);
+      if (Number.isInteger(seconds) && seconds >= 0) {
+        return seconds * 1000; // Convert seconds to milliseconds
+      }
+    }
+    return undefined;
+  }
+
   /**
    * Returns whether Gemini 3.1 Flash Lite has been launched.
    *

packages/core/src/core/baseLlmClient.test.ts

@@ -102,6 +102,7 @@ describe('BaseLlmClient', () => {
     );
 
     mockConfig = {
+      getRequestTimeoutMs: vi.fn().mockReturnValue(undefined),
       getSessionId: vi.fn().mockReturnValue('test-session-id'),
       getContentGeneratorConfig: vi
         .fn()

packages/core/src/core/client.test.ts

@@ -203,6 +203,7 @@ describe('Gemini Client (client.ts)', () => {
       authType: AuthType.USE_GEMINI,
     };
     mockConfig = {
+      getRequestTimeoutMs: vi.fn().mockReturnValue(undefined),
       getContentGeneratorConfig: vi
         .fn()
         .mockReturnValue(contentGeneratorConfig),

packages/core/src/core/geminiChat.test.ts

@@ -142,6 +142,7 @@ describe('GeminiChat', () => {
     let currentActiveModel = 'gemini-pro';
 
     mockConfig = {
+      getRequestTimeoutMs: vi.fn().mockReturnValue(undefined),
       get config() {
         return this;
       },

packages/core/src/core/geminiChat_network_retry.test.ts

@@ -83,6 +83,7 @@ describe('GeminiChat Network Retries', () => {
     const testMessageBus = { publish: vi.fn(), subscribe: vi.fn() };
 
     mockConfig = {
+      getRequestTimeoutMs: vi.fn().mockReturnValue(undefined),
       get config() {
         return this;
       },

packages/core/src/utils/fetch.test.ts

@@ -4,21 +4,37 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { updateGlobalFetchTimeouts } from './fetch.js';
 import { describe, it, expect, vi, beforeEach, afterAll } from 'vitest';
-import {
-  isPrivateIp,
-  isPrivateIpAsync,
-  isAddressPrivate,
-  fetchWithTimeout,
-} from './fetch.js';
 import * as dnsPromises from 'node:dns/promises';
 import type { LookupAddress, LookupAllOptions } from 'node:dns';
 import ipaddr from 'ipaddr.js';
 
+const { setGlobalDispatcher, Agent, ProxyAgent } = vi.hoisted(() => ({
+  setGlobalDispatcher: vi.fn(),
+  Agent: vi.fn(),
+  ProxyAgent: vi.fn(),
+}));
+
+vi.mock('undici', () => ({
+  setGlobalDispatcher,
+  Agent,
+  ProxyAgent,
+}));
+
 vi.mock('node:dns/promises', () => ({
   lookup: vi.fn(),
 }));
 
+// Import after mocks are established
+const {
+  isPrivateIp,
+  isPrivateIpAsync,
+  isAddressPrivate,
+  fetchWithTimeout,
+  setGlobalProxy,
+} = await import('./fetch.js');
+
 // Mock global fetch
 const originalFetch = global.fetch;
 global.fetch = vi.fn();
@@ -183,4 +199,19 @@ describe('fetch utils', () => {
       );
     });
   });
+
+  describe('setGlobalProxy', () => {
+    it('should configure ProxyAgent with experiment flag timeout', () => {
+      const proxyUrl = 'http://proxy.example.com';
+      updateGlobalFetchTimeouts(45773134);
+      setGlobalProxy(proxyUrl);
+
+      expect(ProxyAgent).toHaveBeenCalledWith({
+        uri: proxyUrl,
+        headersTimeout: 45773134,
+        bodyTimeout: 45773134,
+      });
+      expect(setGlobalDispatcher).toHaveBeenCalled();
+    });
+  });
 });

packages/core/src/utils/fetch.ts

@@ -10,9 +10,6 @@ import { Agent, ProxyAgent, setGlobalDispatcher } from 'undici';
 import ipaddr from 'ipaddr.js';
 import { lookup } from 'node:dns/promises';
 
-const DEFAULT_HEADERS_TIMEOUT = 300000; // 5 minutes
-const DEFAULT_BODY_TIMEOUT = 300000; // 5 minutes
-
 export class FetchError extends Error {
   constructor(
     message: string,
@@ -31,14 +28,31 @@ export class PrivateIpError extends Error {
   }
 }
 
+let defaultTimeout = 300000; // 5 minutes
+let currentProxy: string | undefined = undefined;
+
 // Configure default global dispatcher with higher timeouts
 setGlobalDispatcher(
   new Agent({
-    headersTimeout: DEFAULT_HEADERS_TIMEOUT,
-    bodyTimeout: DEFAULT_BODY_TIMEOUT,
+    headersTimeout: defaultTimeout,
+    bodyTimeout: defaultTimeout,
   }),
 );
 
+export function updateGlobalFetchTimeouts(timeoutMs: number) {
+  defaultTimeout = timeoutMs;
+  if (currentProxy) {
+    setGlobalProxy(currentProxy);
+  } else {
+    setGlobalDispatcher(
+      new Agent({
+        headersTimeout: defaultTimeout,
+        bodyTimeout: defaultTimeout,
+      }),
+    );
+  }
+}
+
 /**
  * Sanitizes a hostname by stripping IPv6 brackets if present.
  */
@@ -191,11 +205,12 @@ export async function fetchWithTimeout(
 }
 
 export function setGlobalProxy(proxy: string) {
+  currentProxy = proxy;
   setGlobalDispatcher(
     new ProxyAgent({
       uri: proxy,
-      headersTimeout: DEFAULT_HEADERS_TIMEOUT,
-      bodyTimeout: DEFAULT_BODY_TIMEOUT,
+      headersTimeout: defaultTimeout,
+      bodyTimeout: defaultTimeout,
     }),
   );
 }