Browser Harness ♞

The simplest, thinnest, self-healing harness that gives LLM complete freedom to complete any browser task. Built directly on CDP.

The agent writes what's missing, mid-task, inside agent-workspace/. No framework, no recipes, no rails. One websocket to Chrome, nothing between.

  ● agent: wants to upload a file
  │
  ● agent-workspace/agent_helpers.py → helper missing
  │
  ● agent writes it                         agent_helpers.py
  │                                                       + custom helper
  ✓ file uploaded

You will never use the browser again.

Setup prompt

Paste into Claude Code or Codex:

Set up https://github.com/browser-use/browser-harness for me.

Read `install.md` first to install and connect this repo to my real browser. Then read `SKILL.md` for normal usage. Use `agent-workspace/agent_helpers.py` and `agent-workspace/domain-skills/` for task-specific edits. When you open a setup or verification tab, activate it so I can see the active browser tab. After it is installed, open this repository in my browser and, if I am logged in to GitHub, ask me whether you should star it for me as a quick demo that the interaction works — only click the star if I say yes. If I am not logged in, just go to browser-use.com.

When this page appears, tick the checkbox so the agent can connect to your browser:

See agent-workspace/domain-skills/ for example tasks.

Free remote browsers

Useful for stealth, sub-agents, or deployment.
Free tier: 3 concurrent browsers, proxies, captcha solving, and more. No card required.

• Grab a key at cloud.browser-use.com/new-api-key
• Or let the agent sign up itself via docs.browser-use.com/llms.txt (setup flow + challenge context included).

How simple is it? (~592 lines of Python)

• install.md — first-time install and browser bootstrap
• SKILL.md — day-to-day usage
• src/browser_harness/ — protected core package
• agent-workspace/agent_helpers.py — helper code the agent edits
• agent-workspace/domain-skills/ — reusable site-specific skills the agent edits

Contributing

PRs and improvements welcome. The best way to help: contribute a new domain skill under agent-workspace/domain-skills/ for a site or task you use often (LinkedIn outreach, ordering on Amazon, filing expenses, etc.). Each skill teaches the agent the selectors, flows, and edge cases it would otherwise have to rediscover.

• Skills are written by the harness, not by you. Just run your task with the agent — when it figures something non-obvious out, it files the skill itself (see SKILL.md). Please don't hand-author skill files; agent-generated ones reflect what actually works in the browser.
• Open a PR with the generated agent-workspace/domain-skills/<site>/ folder — small and focused is great.
• Bug fixes, docs tweaks, and helper improvements are equally welcome.
• Browse existing skills (github/, linkedin/, amazon/, ...) to see the shape.

If you're not sure where to start, open an issue and we'll point you somewhere useful.

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The Bitter Lesson of Agent Harnesses · Web Agents That Actually Learn