Browser canvas WebView closes when loading a JavaScript-heavy localhost page #4776

Description

The browser canvas becomes stuck on its loading UI when opening an authenticated, JavaScript-heavy application hosted on localhost. The target page works correctly in a regular browser such as Chrome.

Environment

• Copilot App version: 1.0.83-5
• OS: macOS
• Target: http://localhost:3001/...
• Application: local React web application

Steps to reproduce

1. Open a localhost application login page in the Copilot browser canvas.
2. Sign in successfully.
3. Navigate to a specific page using a query parameter.
4. Wait for the page to initialize.

Expected behavior

The authenticated page loads in the browser canvas as it does in Chrome.

Actual behavior

The browser canvas remains on its loading UI. Browser canvas diagnostics initially show that login succeeds, but when the target page begins loading, the WebView is closed or becomes unavailable. Subsequent browser tool calls return:

Browser page load waiter closed.
webview not found

A second browser canvas could load the login page, but browser interactions later began timing out:

Browser tool request timed out.

The localhost server remains reachable, and the same page continues to work in a regular browser.

Additional notes

The target application loads a large React bundle. This may be related to WebView compatibility, renderer-process termination, or browser canvas resource limits. No credentials, product names, versions, or private page paths are included in this report.