Browser Harness Js

Browser Harness JS ♞

The thinnest possible bridge from the LLM to Chrome. **No harness, no recipes, no rails** — just every CDP method as a typed JS call.

One persistent WebSocket, 56 domains, 652 typed wrappers, zero wrapping of what Chrome already does.

  ● agent: wants to click a button
  │
  ● no click() helper, no upload_file(), no goto()
  │
  ● agent writes the CDP call itself        await session.Input.dispatchMouseEvent({...})
  │                                          await session.DOM.setFileInputFiles({...})
  ✓ done — same pattern for all 652 methods

**The protocol is the API.** If Chrome can do it, you can call it.

Installation

npx skills add https://github.com/browser-use/browser-harness-js --skill cdp

Or paste this into your agent — it'll install the skill, put the CLI on your PATH, and run a first task:

Run `npx skills add https://github.com/browser-use/browser-harness-js --skill cdp`, then
symlink `browser-harness-js` into a directory on my PATH, then use the cdp skill to drive
my browser: look at all the tabs I have open, group them by topic, and screenshot the most
interesting one.

(The CLI auto-installs [`bun`](https://bun.sh) on first run if it's missing. Set `BROWSER_HARNESS_SKIP_BUN_INSTALL=1` to opt out.)

If Chrome asks you to tick a remote-debugging checkbox, do it — that's how the agent attaches:

See [interaction-skills/](interaction-skills/) for recipes on the mechanics that are not obvious from the CDP method list alone.

Files

• SKILL.md — day-to-day usage; how to connect, pick a tab, call methods, persist state
• sdk/browser-harness-js — tiny CLI that auto-spawns the server and forwards snippets
• sdk/repl.ts — Bun HTTP server holding one persistent `Sessio