one-agent-one-browser

Btw, after I wrote that initial article ("Cursor's latest "browser experiment" implied success without evidence"), I gave it my own try to write a browser from scratch with just one agent, using no 3rd party crates, only commonly available system libraries, and just made a Show HN about it: https://news.ycombinator.com/item?id=46779522 The end result: Me and one agent (codex) managed to build something more or less the same as Cursor's "hundreds of agents" running for weeks and producing millions of lines of code, in just 20K LOC (this includes X11, macOS and Windows support). Has --headless, --screenshot, handles scaling, link clicking and scrolling, and can render basic websites mostly fine (like HN) and most others not so fine. Also included CI builds and automatic releases because why not. The repository itself is here and should run

This is a notably better demonstration of a coding agent generated browser than Cursor's FastRender - it's a fraction of the size (20,000 lines of Rust compared to ~1.6m), uses way fewer dependencies (just system libraries for rendering images and text) and the code is actually quite readable - here's the flexbox implementation, for example: https://github.com/embedding-shapes/one-agent-one-browser/bl... Here's my own screenshot of it rendering my blog - https://bsky.app/profile/simonwillison.net/post/3mdg2oo6bms2... - it handles the layout and CSS gradiants really well, renders the SVG feed icon but fails to render a PNG image. I thought "build a browser that renders HTML+CSS" was the perfect task for demonstrating a massively parallel agent setup because it couldn't be productively achieved in a few thousand lines of code by a single co