Hi HN! Pierce here.

Rotunda is a firefox fork primarily intended for agent use, which I’ve been hacking on nights/weekends.

There was a [lengthy](https://news.ycombinator.com/item?id=48024859) discussion last week on how expensive computer use models are. The cost is going to drop eventually, but I think on some level it's still usually the wrong primitive. The web gives us access to beautiful structured formats, plaintext, etc... why throw that away if we don't have to?

I realized at some point that for 99% of automations I just want agents to be able to control my Chrome instance. But that’s easier said that done: CDP (the Chrome automation protocol) leaks a ton of state about being programmatically controlled, either by toggling window attributes or by running `page.evaluate()` commands right in the page context. Plus if you look at an automation running it's pretty obvious what happens: the mouse jumps around, fields are filled instantly, etc.

Rotunda tries to fix this. Its standout features:

- Realistic simulation of mouse movements and keyboard commands, powered by a trained RNN on my own timing patterns from the last week. (still feel weird about opting-in to a key logger but whatever)

- Doesn’t lie about its host specs, only fibs about some client side details. Stealth browsers are too easy to flag statistically when you’re adding noise to canvas pixels or audio pipelines.

- It runs on your local device with a CLI or Playwright API accessible to Claude, Codex, or whatever your harness-de-jure today looks like.

- Patches modern Firefox (150) with an agentic harness to keep this updated over time

MPL-2.0 on GitHub: https://github.com/monkeysee-ai/rotunda

Longer writeup on the design choices: https://pierce.dev/notes/a-browser-for-agents

Also check out the demo on the site! https://www.rotunda.sh/

Pretty excited by how this turned out but we’re still super early. Give it a try and please flag any issues!

Show HN: Rotunda - A browser built for agents with simulated typing