From 9d642f3bb1dcf8380822b025adabb06262364ef2 Mon Sep 17 00:00:00 2001
From: Allen Hutchison <adh@google.com>
Date: Mon, 3 Nov 2025 10:13:52 -0800
Subject: [PATCH] refactor(core): improve error handling for setGlobalProxy
 (#12437)

---
 packages/core/src/config/config.test.ts | 71 +++++++++++++++++++++++++
 packages/core/src/config/config.ts      | 14 ++++-
 packages/core/src/tools/web-fetch.ts    | 10 +---
 packages/core/src/utils/fetch.ts        |  6 +--
 4 files changed, 85 insertions(+), 16 deletions(-)

diff --git a/packages/core/src/config/config.test.ts b/packages/core/src/config/config.test.ts
index ae5ddaa573..e50b31829d 100644
--- a/packages/core/src/config/config.test.ts
+++ b/packages/core/src/config/config.test.ts
@@ -145,6 +145,20 @@ vi.mock('../agents/subagent-tool-wrapper.js', () => ({
   SubagentToolWrapper: vi.fn(),
 }));
 
+const mockCoreEvents = vi.hoisted(() => ({
+  emitFeedback: vi.fn(),
+}));
+
+const mockSetGlobalProxy = vi.hoisted(() => vi.fn());
+
+vi.mock('../utils/events.js', () => ({
+  coreEvents: mockCoreEvents,
+}));
+
+vi.mock('../utils/fetch.js', () => ({
+  setGlobalProxy: mockSetGlobalProxy,
+}));
+
 import { BaseLlmClient } from '../core/baseLlmClient.js';
 import { tokenLimit } from '../core/tokenLimits.js';
 import { uiTelemetryService } from '../telemetry/index.js';
@@ -912,6 +926,63 @@ describe('Server Config (config.ts)', () => {
       expect(config.getTruncateToolOutputThreshold()).toBe(50000);
     });
   });
+
+  describe('Proxy Configuration Error Handling', () => {
+    beforeEach(() => {
+      vi.clearAllMocks();
+    });
+
+    it('should call setGlobalProxy when proxy is configured', () => {
+      const paramsWithProxy: ConfigParameters = {
+        ...baseParams,
+        proxy: 'http://proxy.example.com:8080',
+      };
+      new Config(paramsWithProxy);
+
+      expect(mockSetGlobalProxy).toHaveBeenCalledWith(
+        'http://proxy.example.com:8080',
+      );
+    });
+
+    it('should not call setGlobalProxy when proxy is not configured', () => {
+      new Config(baseParams);
+
+      expect(mockSetGlobalProxy).not.toHaveBeenCalled();
+    });
+
+    it('should emit error feedback when setGlobalProxy throws an error', () => {
+      const proxyError = new Error('Invalid proxy URL');
+      mockSetGlobalProxy.mockImplementation(() => {
+        throw proxyError;
+      });
+
+      const paramsWithProxy: ConfigParameters = {
+        ...baseParams,
+        proxy: 'invalid-proxy',
+      };
+      new Config(paramsWithProxy);
+
+      expect(mockCoreEvents.emitFeedback).toHaveBeenCalledWith(
+        'error',
+        'Invalid proxy configuration detected. Check debug drawer for more details (F12)',
+        proxyError,
+      );
+    });
+
+    it('should not emit error feedback when setGlobalProxy succeeds', () => {
+      mockSetGlobalProxy.mockImplementation(() => {
+        // Success - no error thrown
+      });
+
+      const paramsWithProxy: ConfigParameters = {
+        ...baseParams,
+        proxy: 'http://proxy.example.com:8080',
+      };
+      new Config(paramsWithProxy);
+
+      expect(mockCoreEvents.emitFeedback).not.toHaveBeenCalled();
+    });
+  });
 });
 
 describe('setApprovalMode with folder trust', () => {
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index c610202bf8..8dab6cbaa4 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -76,6 +76,7 @@ import type { UserTierId } from '../code_assist/types.js';
 import { AgentRegistry } from '../agents/registry.js';
 import { setGlobalProxy } from '../utils/fetch.js';
 import { SubagentToolWrapper } from '../agents/subagent-tool-wrapper.js';
+import { coreEvents } from '../utils/events.js';
 
 export enum ApprovalMode {
   DEFAULT = 'default',
@@ -582,8 +583,17 @@ export class Config {
       initializeTelemetry(this);
     }
 
-    if (this.getProxy()) {
-      setGlobalProxy(this.getProxy() as string);
+    const proxy = this.getProxy();
+    if (proxy) {
+      try {
+        setGlobalProxy(proxy);
+      } catch (error) {
+        coreEvents.emitFeedback(
+          'error',
+          'Invalid proxy configuration detected. Check debug drawer for more details (F12)',
+          error,
+        );
+      }
     }
     this.geminiClient = new GeminiClient(this);
     this.modelRouterService = new ModelRouterService(this);
diff --git a/packages/core/src/tools/web-fetch.ts b/packages/core/src/tools/web-fetch.ts
index c914885af9..c3ffe373a4 100644
--- a/packages/core/src/tools/web-fetch.ts
+++ b/packages/core/src/tools/web-fetch.ts
@@ -21,11 +21,7 @@ import { getErrorMessage } from '../utils/errors.js';
 import type { Config } from '../config/config.js';
 import { ApprovalMode, DEFAULT_GEMINI_FLASH_MODEL } from '../config/config.js';
 import { getResponseText } from '../utils/partUtils.js';
-import {
-  fetchWithTimeout,
-  isPrivateIp,
-  setGlobalProxy,
-} from '../utils/fetch.js';
+import { fetchWithTimeout, isPrivateIp } from '../utils/fetch.js';
 import { convert } from 'html-to-text';
 import {
   logWebFetchFallbackAttempt,
@@ -415,10 +411,6 @@ export class WebFetchTool extends BaseDeclarativeTool<
       false, // canUpdateOutput
       messageBus,
     );
-    const proxy = config.getProxy();
-    if (proxy) {
-      setGlobalProxy(proxy);
-    }
   }
 
   protected override validateToolParamValues(
diff --git a/packages/core/src/utils/fetch.ts b/packages/core/src/utils/fetch.ts
index ffe6165507..ba9bb83c80 100644
--- a/packages/core/src/utils/fetch.ts
+++ b/packages/core/src/utils/fetch.ts
@@ -58,9 +58,5 @@ export async function fetchWithTimeout(
 }
 
 export function setGlobalProxy(proxy: string) {
-  try {
-    setGlobalDispatcher(new ProxyAgent(proxy));
-  } catch (e) {
-    console.error(`Failed to set proxy: ${getErrorMessage(e)}`);
-  }
+  setGlobalDispatcher(new ProxyAgent(proxy));
 }