Browser Driver

Browser Driver (system browser over CDP)

Drive the user's own, already-logged-in browser via CDP + Playwright. The user watches every step; you screenshot after each mutating action so both you and the user can audit.

Why the system browser, not a fresh Playwright Chromium

A fresh Playwright profile has no sessions — the user would re-log-in with 2FA from scratch. The user's own Chromium browser already holds the session, so there is zero login friction. You attach to it over a debug port; you do not replace it.

When to use this — and when NOT to (avoid tool conflict)

This skill exists for exactly one thing the other browser tools cannot do: attach to the user's real browser and its existing login. Reach for it only when all of these hold:

• The task needs the user's existing session / login (would otherwise require logging in, often with 2FA), AND
• A fresh or headless browser profile would land on a login screen, AND
• The user wants it done in their own browser, typically watching live.

Signals: "do it in my browser", "use my login / my session", "I'm already signed in", "don't make me log in again", a console/dashboard behind SSO+2FA.

Do NOT use this skill — defer to the agent's built-in browser tooling — for:

• ordinary browsing, fetching, or scraping of public or unauthenticated pages,
• headless end-to-end tests or CI automation,
• anything where a clean throwaway profile is fine (no real login needed),
• when the agent already has a browser tool / Playwright MCP / chrome-devtools MCP / computer-use that satisfies the task without the user's live session.

If the built-in tooling can do it, use that and stop — do not load this skill's reference files. Only load references/* once you have actually committed to driving the system browser, so an irrelevant browser task costs ~0 extra tokens (just this short description).

Scope boundary (read first)

Only ever drive the user's own browser, own sessions, own accounts, with their knowledge and present consent. Never use this to bypass authentication, defeat a security control, or reach an account that is not theirs. Identity walls (Touch ID, security key, liveness/QR) are handed back to the user — never attempt to defeat or proxy them.

Workflow

1. Check where the agent runs vs where the browser is. If you (the agent) run on the same machine as the user's logged-in browser, proceed normally. If you run on a remote host (VPS) and the browser is on the user's local machine, you must bridge the CDP port over an SSH reverse tunnel first — references/remote-over-tunnel.md. If the only browser is a headless one on the VPS, there is no existing user session to reuse and this skill does not apply.
2. Pick the browser + port. Any Chromium-based browser works (Chrome, Edge, Brave). Choose a non-default debug port (e.g. 9223) to avoid clashes.
3. Launch with the debug port so tabs/session restore — references/launch-and-drive.md.
4. Probe the port until it answers, then attach.
5. Drive one step at a time with short, one-shot scripts that connect fresh, act, screenshot, and detach — references/launch-and-drive.md.
6. Read the screenshot after every mutating step. That is how you "see" the page and how the user audits.
7. Handle selectors for modern SPAs (shadow DOM, overlays, display-vs-internal names) — references/selectors-and-handoffs.md.
8. Hand control to the user at identity walls, then poll for completion — references/selectors-and-handoffs.md.
9. Capture one-time secrets straight to a file, never to chat — references/selectors-and-handoffs.md.
10. Clean up: restart the browser normally so no open debug port lingers — references/selectors-and-handoffs.md.

Core rules

• One-shot scripts, not a long-lived process. A long-running Playwright process dies with the shell. Connect fresh per step with connectOverCDP, act, then browser.close() (this only detaches — the user's browser stays open).
• Screenshot every mutating step and Read the PNG before the next action. No blind clicking.
• Locators over querySelectorAll. Playwright locators pierce shadow DOM; raw document.querySelectorAll inside page.evaluate does not.
• DOM-click through overlays. When something "intercepts pointer events", locator.evaluate(el => el.click()) fires a DOM click and skips hit-testing; force: true is often not enough.
• Stop at identity walls. Click up to the wall, tell the user exactly what to do, then poll page text or a source-of-truth API until it clears.
• Secrets shown once go to a file, never to chat. Regex the value out of the page text into a temp file, store it in the user's password manager, then shred the temp file.

Reference files (load on demand)

• references/launch-and-drive.md — launch-with-debug-port sequence (and why open --args is unreliable right after quit), the probe, and the per-step one-shot script pattern with screenshot auditing.
• references/selectors-and-handoffs.md — SPA selector gotchas (shadow DOM, overlays, display vs internal names), identity-wall handoff + polling, one-time-secret capture, cleanup, and a stdout-corruption gotcha.
• references/remote-over-tunnel.md — when the agent is remote (VPS) and the browser is on the user's local machine: bridge the CDP port over a loopback-only SSH reverse tunnel; security rules for unauthenticated CDP; when this skill does not apply (headless VPS, no user session).