Browser Agents Need Stateful VMs

Effective browser agents require more than just a browser API — realistic agents need Chromium or Firefox, a display stack, a browser profile, downloads, cookies, screenshots, accessibility trees, network logs, local files, credentials, a test runner, and supporting infrastructure like dev servers and databases running on the same system. Both web operations (logging in, filling forms, scraping data) and web development use cases demand persistent state management across multiple interactions.