fix: Prevent CDP timeout on empty URL tabs (#102)

When connecting to a browser via CDP, particularly on Android, tabs with an empty URL can cause Playwright commands to hang indefinitely. This leads to a timeout in agent-browser.

This commit fixes the issue by filtering out any pages that have an empty `page.url()` during the CDP connection process. This prevents agent-browser from attempting to interact with these problematic tabs, resolving the timeout while preserving normal pages.

Added a unit test to verify that pages with empty URLs are correctly ignored. Also increased the timeout for a flaky screencast test to improve test suite stability.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: sheing-google <231310897+sheing-google@users.noreply.github.com>

src/browser.test.ts

@@ -1,5 +1,6 @@
-import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { describe, it, expect, beforeAll, afterAll, vi } from 'vitest';
 import { BrowserManager } from './browser.js';
+import { chromium } from 'playwright-core';
 
 describe('BrowserManager', () => {
   let browser: BrowserManager;
@@ -390,6 +391,35 @@ describe('BrowserManager', () => {
       const cdp2 = await browser.getCDPSession();
       expect(cdp1).toBe(cdp2);
     });
+
+    it('should filter out pages with empty URLs during CDP connection', async () => {
+      const mockBrowser = {
+        contexts: () => [
+          {
+            pages: () => [
+              { url: () => 'http://example.com', on: vi.fn() },
+              { url: () => '', on: vi.fn() }, // This page should be filtered out
+              { url: () => 'http://anothersite.com', on: vi.fn() },
+            ],
+            on: vi.fn(),
+          },
+        ],
+        close: vi.fn(),
+      };
+      const spy = vi.spyOn(chromium, 'connectOverCDP').mockResolvedValue(mockBrowser as any);
+
+      const cdpBrowser = new BrowserManager();
+      await cdpBrowser.launch({ cdpPort: 9222 });
+
+      // Should have 2 pages, not 3
+      expect(cdpBrowser.getPages().length).toBe(2);
+
+      // Verify that the empty URL page is not in the list
+      const urls = cdpBrowser.getPages().map((p) => p.url());
+      expect(urls).not.toContain('');
+      expect(urls).toContain('http://example.com');
+      spy.mockRestore();
+    });
   });
 
   describe('screencast', () => {
@@ -405,7 +435,7 @@ describe('BrowserManager', () => {
       expect(browser.isScreencasting()).toBe(true);
 
       // Wait a bit for at least one frame
-      await new Promise((resolve) => setTimeout(resolve, 200));
+      await new Promise((resolve) => setTimeout(resolve, 1000));
 
       await browser.stopScreencast();
       expect(browser.isScreencasting()).toBe(false);

src/browser.ts

@@ -738,7 +738,11 @@ export class BrowserManager {
         throw new Error('No browser context found. Make sure the app has an open window.');
       }
 
-      const allPages = contexts.flatMap((context) => context.pages());
+      // Filter out pages with empty URLs, which can cause Playwright to hang
+      const allPages = contexts
+        .flatMap((context) => context.pages())
+        .filter((page) => page.url());
+
       if (allPages.length === 0) {
         throw new Error('No page found. Make sure the app has loaded content.');
       }