Stagehand V4

Browserbase's Stagehand v4 moves much of its browser-control machinery into an extension running inside the browser itself. The engineering explanation identifies a problem with remote automation: a script keeps a local copy of the browser's pages and frames, and when the browser is far away that copy can go stale, so a command such as a click can arrive at a page that has already navigated or closed.

In v4 the extension tracks pages and frames inside the browser, and the client asks the browser for the current state instead of maintaining as much of its own copy. Because most of the logic now lives in the extension, the TypeScript, Python and Go clients are thin layers over one shared core. Browserbase describes this as consolidating most state management in the browser while noting that some client-side state remains. The post is Browserbase's own account; its speed comparison is labeled by the company as a single run, not a benchmark.