feat(core): implement persistent browser session management (#21306)

Co-authored-by: Gaurav <39389231+gsquared94@users.noreply.github.com>
Co-authored-by: cynthialong0-0 <82900738+cynthialong0-0@users.noreply.github.com>

packages/core/src/agents/browser/browserAgentInvocation.test.ts

@@ -26,7 +26,10 @@ vi.mock('../../utils/debugLogger.js', () => ({
 
 vi.mock('./browserAgentFactory.js', () => ({
   createBrowserAgentDefinition: vi.fn(),
-  cleanupBrowserAgent: vi.fn(),
+}));
+
+vi.mock('./inputBlocker.js', () => ({
+  removeInputBlocker: vi.fn(),
 }));
 
 vi.mock('../local-executor.js', () => ({
@@ -35,10 +38,8 @@ vi.mock('../local-executor.js', () => ({
   },
 }));
 
-import {
-  createBrowserAgentDefinition,
-  cleanupBrowserAgent,
-} from './browserAgentFactory.js';
+import { createBrowserAgentDefinition } from './browserAgentFactory.js';
+import { removeInputBlocker } from './inputBlocker.js';
 import { LocalAgentExecutor } from '../local-executor.js';
 import type { ToolLiveOutput } from '../../tools/tools.js';
 
@@ -190,7 +191,7 @@ describe('BrowserAgentInvocation', () => {
       vi.mocked(LocalAgentExecutor.create).mockResolvedValue(
         mockExecutor as never,
       );
-      vi.mocked(cleanupBrowserAgent).mockClear();
+      vi.mocked(removeInputBlocker).mockClear();
     });
 
     it('should return result text and call cleanup on success', async () => {
@@ -209,7 +210,7 @@ describe('BrowserAgentInvocation', () => {
       expect((result.llmContent as Array<{ text: string }>)[0].text).toContain(
         'Browser agent finished',
       );
-      expect(cleanupBrowserAgent).toHaveBeenCalled();
+      expect(removeInputBlocker).toHaveBeenCalled();
     });
 
     it('should work without updateOutput (fire-and-forget)', async () => {
@@ -239,7 +240,7 @@ describe('BrowserAgentInvocation', () => {
       const result = await invocation.execute(controller.signal);
 
       expect(result.error).toBeDefined();
-      expect(cleanupBrowserAgent).toHaveBeenCalled();
+      expect(removeInputBlocker).toHaveBeenCalled();
     });
 
     // ─── Structured SubagentProgress emission tests ───────────────────────