/SKILL.md

---
name: browser-harness
description: Direct browser control via CDP. Use when the user wants to automate, scrape, test, or interact with web pages. Connects to the user's already-running Chrome.
---

# browser-harness

Easiest and most powerful way to interact with the browser. Read this file in full before using or editing the harness — it has to be in context.

## Fast start

Read `helpers.py` first. For first-time install or reconnect/bootstrap, read `install.md` first.

## Self-maintenance

- `browser-harness --doctor` — diagnose install, daemon, browser, and whether an update is available.
- `browser-harness --setup` — re-run the interactive browser-attach flow (equivalent to the bootstrap in `install.md`).
- `browser-harness --update -y` — pull the latest version and restart the daemon without prompting. If you see a banner like `[browser-harness] update available: X -> Y` at the top of a run, run this yourself — don't ask the user first. The banner is rate-limited to once per day.

```bash
browser-harness <<'PY'
new_tab("https://docs.browser-use.com")
wait_for_load()
print(page_info())
PY
```

- Invoke as `browser-harness` — it's on `$PATH`. No `cd`, no `uv run`.
- First navigation is `new_tab(url)`, not `goto(url)` — `goto` runs in the user's active tab and clobbers their work.

The code is the doc.

Available interaction skills:
- `interaction-skills/connection.md` — startup sequence, tab visibility, omnibox popup fix

Available domain skills:
- `tiktok/upload.md`

## Tool call shape

```bash
browser-harness <<'PY'
# any python. helpers pre-imported. daemon auto-starts.
PY
```

`run.py` calls `ensure_daemon()` before `exec` — you never start/stop manually unless you want to.

### Remote browsers

Use remote for parallel sub-agents (each gets its own isolated browser via a distinct `BU_NAME`) or on a headless server. `BROWSER_USE_API_KEY` must be set. `start_remote_daemon`, `list_cloud_profiles`, `list_local_profiles`, `sync_local_profile` are pre-imported.

```bash
browser-harness <<'PY'
start_remote_daemon("work")                               # default — clean browser, no profile
# start_remote_daemon("work", profileName="my-work")      # reuse a cloud profile (already logged in)
# start_remote_daemon("work", profileId="<uuid>")         # same, but by UUID
# start_remote_daemon("work", proxyCountryCode="de", timeout=120)   # DE proxy, 2-hour timeout
# start_remote_daemon("work", proxyCountryCode=None)      # disable the Browser Use proxy
PY

BU_NAME=work browser-harness <<'PY'
new_tab("https://example.com")
print(page_info())
PY
```

`start_remote_daemon` prints `liveUrl` and auto-opens it in the local browser (if a GUI is detected) so the user can watch along. Headless servers print only — share the URL with the user. The daemon `PATCH`es the cloud browser to `stop` on shutdown, which persists profile state. Running remote daemons bill until timeout.

Profiles (cookies-only login state) live in `interaction-skills/profile-sync.md` — covers `list_cloud_profiles()`, the chat-driven "which profile?" pattern, and `sync_local_profile()` for uploading a local Chrome profile.

## Search first

After cloning the repo, search `domain-skills/` first for the domain you are working on before inventing a new approach.

Only if you start struggling with a specific mechanic while navigating, look in `interaction-skills/` for helpers. The available interaction skills are:
- `cookies.md`
- `cross-origin-iframes.md`
- `dialogs.md`
- `downloads.md`
- `drag-and-drop.md`
- `dropdowns.md`
- `iframes.md`
- `network-requests.md`
- `print-as-pdf.md`
- `profile-sync.md`
- `screenshots.md`
- `scrolling.md`
- `shadow-dom.md`
- `tabs.md`
- `uploads.md`
- `viewport.md`

Useful commands:

```bash
rg --files domain-skills
rg -n "tiktok|upload" domain-skills
```

## Always contribute back

If you learned anything non-obvious about how a site works, open a PR to `domain-skills/<site>/` before you finish. Default to contributing. The harness gets better only because agents file what they learn. If figuring something out cost you a few steps, the next run should not pay the same tax.

Examples of what's worth a PR:

- A private API the page calls (XHR/fetch endpoint, request shape, auth) — often 10× faster than DOM scraping.
- A stable selector that beats the obvious one, or an obfuscated CSS-module class to avoid.
- A framework quirk — "the dropdown is a React combobox that only commits on Escape", "this Vue list only renders rows inside its own scroll container, so `scrollIntoView` on the row doesn't work — you have to scroll the container".
- A URL pattern — direct route, required query params (`?lang=en`, `?th=1`), a variant that skips a loader.
- A wait that `wait_for_load()` misses, with the reason.
- A trap — stale drafts, legacy IDs that now return null, unicode quirks, beforeunload dialogs, CAPTCHA surfaces.

### What a domain skill should capture

The *durable* shape of the site — the map, not the diary. Focus on what the next agent on this site needs to know before it starts:

- URL patterns and query params.
- Private APIs and their payload shape.
- Stable selectors (`data-*`, `aria-*`, `role`, semantic classes).
- Site structure — containers, items per page, framework, where state lives.
- Framework/interaction quirks unique to this site.
- Waits and the reasons they're needed.
- Traps and the selectors that *don't* work.

### Do not write

- Raw pixel coordinates. They break on viewport, zoom, and layout changes. Describe how to *locate* the target (selector, `scrollIntoView`, `aria-label`, visible text) — never where it happened to be on your screen.
- Run narration or step-by-step of the specific task you just did.
- Secrets, cookies, session tokens, user-specific state. `domain-skills/` is shared and public.

## What actually works

- Screenshots first: use `screenshot()` to understand the current page quickly, find visible targets, and decide whether you need a click, a selector, or more navigation.
- Clicking: `screenshot()` → read the pixel off the image → `click(x, y)` → `screenshot()` to verify. Suppress the Playwright-habit reflex of "locate first, then click" — no `getBoundingClientRect`, no selector hunt. Drop to DOM only when the target has no visible geometry (hidden input, 0×0 node). Hit-testing happens in Chrome's browser process, so clicks go through iframes / shadow DOM / cross-origin without extra work.
- Bulk HTTP: `http_get(url)` + `ThreadPoolExecutor`. No browser for static pages (249 Netflix pages in 2.8s).
- After goto: `wait_for_load()`.
- Wrong/stale tab: `ensure_real_tab()`. Use it when the current tab is stale or internal; the daemon also auto-recovers from stale sessions on the next call.
- Verification: `print(page_info())` is the simplest "is this alive?" check, but screenshots are the default way to verify whether a visible action actually worked.
- DOM reads: use `js(...)` for inspection and extraction when the screenshot shows that coordinates are the wrong tool.
- Iframe sites (Azure blades, Salesforce): `click(x, y)` passes through; only drop to iframe DOM work when coordinate clicks are the wrong tool.
- Auth wall: redirected to login → stop and ask the user. Don't type credentials from screenshots.
- Raw CDP for anything helpers don't cover: `cdp("Domain.method", params)`.

## Design constraints

- Coordinate clicks default. `Input.dispatchMouseEvent` goes through iframes/shadow/cross-origin at the compositor level.
- Connect to the user's running Chrome. Don't launch your own browser.
- `cdp-use` is only for `CDPClient.send_raw`. Prefer raw CDP strings over typed wrappers.
- `run.py` stays tiny. No argparse, subcommands, or extra control layer.
- Helpers stay short. Browser primitives in `helpers.py`; daemon/bootstrap and remote session admin live in `admin.py`.
- Don't add a manager layer. No retries framework, session manager, daemon supervisor, config system, or logging framework.

## Architecture

```text
Chrome / Browser Use cloud -> CDP WS -> daemon.py -> /tmp/bu-<NAME>.sock -> run.py
```

- Protocol is one JSON line each way.
- Requests are `{method, params, session_id}` for CDP or `{meta: ...}` for daemon control.
- Responses are `{result}` / `{error}` / `{events}` / `{session_id}`.
- `BU_NAME` namespaces socket, pid, and log files.
- `BU_CDP_WS` overrides local Chrome discovery for remote browsers.
- `BU_BROWSER_ID` + `BROWSER_USE_API_KEY` lets the daemon stop a Browser Use cloud browser on shutdown.

## Gotchas (field-tested)

- Chrome 144+ `chrome://inspect/#remote-debugging` does NOT serve `/json/version`. Read `DevToolsActivePort` instead.
- Try attaching before asking for setup. If `uv run browser-harness` already works, skip the remote-debugging instructions entirely. Decide what to escalate from the harness's error message, not from whether Chrome is visibly running.
- The remote-debugging checkbox is per-profile sticky in Chrome. Once ticked on a profile, every future Chrome launch auto-enables CDP — only navigate to `chrome://inspect/#remote-debugging` when `DevToolsActivePort` is genuinely missing on a fresh profile.
- The first connect may block on Chrome's Allow dialog. If setup hangs, explicitly tell the user to click `Allow` in Chrome if it appears, then keep polling for up to 30 seconds instead of treating follow-on errors as a new failure.
- `DevToolsActivePort` can exist before the port is actually listening. Treat connection refused as "still enabling" and keep polling for up to 30 seconds.
- Chrome may open the profile picker before any real tab exists. If Chrome opens both a profile picker and the remote-debugging page, tell the user to choose their normal profile first, then tick the checkbox and click `Allow` if shown.
- On macOS, if Chrome is already running, prefer AppleScript `open location` over `open -a ... URL`. It reuses the current profile and avoids creating an extra startup path through the profile picker.
- Omnibox popups are fake `page` targets. Filter `chrome://omnibox-popup...` and other internals when you need a real tab.
- CDP target order != Chrome's visible tab-strip order. Use UI automation when the user means "the first/second tab I can see"; `Target.activateTarget` only shows a known target.
- Default daemon sessions can go stale. `ensure_real_tab()` re-attaches to a real page.
- `no close frame received or sent` usually means a stale daemon / websocket. Restart the daemon once with:
  `uv run python - <<'PY'`
  `from admin import restart_daemon`
  `restart_daemon()`
  `PY`
  before assuming setup is wrong.
- If `restart_daemon()` also hangs, kill Chrome entirely (`pkill -9 -f "Google Chrome"`), clean sockets (`rm -f /tmp/bu-default.sock /tmp/bu-default.pid`), reopen Chrome (`open -a "Google Chrome"`), wait 5s, then reconnect. This resets all CDP state.
- Browser Use API is camelCase on the wire. `cdpUrl`, `proxyCountryCode`, etc.
- Remote `cdpUrl` is HTTPS, not ws. Resolve the websocket URL via `/json/version`.
- Stop cloud browsers with `PATCH /browsers/{id}` + `{\"action\":\"stop\"}`.
- After every meaningful action, re-screenshot before assuming it worked. Use the image to verify changed state, open menus, navigation, visible errors, and whether the page is in the state you expected.
- Use screenshots to drive exploration. They are often the fastest way to find the next click target, notice hidden blockers, and decide if a selector is even worth writing.
- Prefer compositor-level actions over framework hacks. Try screenshots, coordinate clicks, and raw key input before adding DOM-specific workarounds.
- If you need framework-specific DOM tricks, check `interaction-skills/` first. That is where dropdown, dialog, iframe, shadow DOM, and form-specific guidance belongs.

## Interaction notes

- `interaction-skills/` holds reusable UI mechanics such as dialogs, tabs, dropdowns, iframes, and uploads.
- `domain-skills/` holds site-specific workflows and should be updated when you discover reusable patterns for a website.