pi-browser-harness

name	pi-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. Default to browser_snapshot for understanding pages and browser_execute_js for surgical reads — browser_screenshot is for visual verification only.

pi-browser-harness

Direct browser control of the user's running Chrome via CDP.

Tool hierarchy

What do you need to know?

  ├─ Page structure / what's clickable / labels?
  │     → browser_snapshot     (DEFAULT — AX tree with @(x,y) per interactive element)
  │
  ├─ A specific element's value / attribute / coords?
  │     → browser_execute_js   (e.g. el.innerText, el.getBoundingClientRect())
  │
  ├─ Network behavior on the current page?
  │     → browser_network_requests
  │
  ├─ Find pages on the web about a topic?
  │     → browser_web_search    (ranked SERP — links only; follow up with browser_read_page)
  │
  ├─ An article's main content as clean text?
  │     → browser_read_page     (reader mode — a url or an owned targetId → boilerplate stripped)
  │
  ├─ JS errors / why did nothing happen after an action?
  │     → browser_console     (DIAGNOSTIC — only when something looks broken)
  │
  └─ Visual rendering (layout / colors / chart drew correctly)?
        → browser_screenshot   (LAST RESORT — pixels only)

Pass @(x,y) from browser_snapshot straight to browser_click. No screenshot round-trip.

browser_web_search and browser_read_page each run in their own isolated tab and never touch the user's current tab. For a multi-source question that needs a synthesized, cited report, use the deep-research skill (or /deep-research <question>): it fans out isolated web-search-researcher subagents over both tools and writes a source-cited Markdown report.

Connection Setup

Browser control is on-demand — the daemon does NOT start automatically. If you try a browser tool and get a not_connected error, tell the user to run /browser-setup first. This opens the daemon and connects to Chrome. Once initialized, all subsequent sessions reuse the same connection silently.

Before calling any browser tool, the runtime checks for the daemon socket at /tmp/pi-browser-daemon.sock. If the socket is missing (user hasn't run /browser-setup), you get: "Browser harness not initialized. Run /browser-setup first".

Do not ask the user. Call browser_setup directly — it spawns the daemon, connects to Chrome, and opens a test tab. The user sees a single "Allow Remote Debugging" prompt the first time. After that, all sessions reuse the same connection. browser_setup is idempotent — safe to call even when already connected.

Connection

You're attached to the user's real Chrome — never launch your own. If auth is required, stop and ask the user. If browser_page_info returns a dialog, handle it first with browser_handle_dialog.

Diagnosing a "nothing happened" moment

When an action runs but the page didn't change, capture browser_console's nextCursor before the action, take the action, then call browser_console({ sinceSeq: <cursor> }) after — this isolates what your action caused from what was already there. Pair with browser_network_requests({ sinceMs: 5000 }) to see if an API call fired and failed. The console buffer is page-scoped: it clears on tab switch, capacity 500.

Temporary scripts

When a workflow repeats 3+ times or needs Node.js APIs, write a script to disk and run it with browser_run_script. Scripts get a daemon binding for direct CDP access — much faster than chaining tool calls.

Bindings inside a script:

• params — args passed to browser_run_script
• daemon:
  • daemon.evaluateJs(expression) — run JS in the current page
  • daemon.pageInfo() — { url, title, ... } or { dialog }
  • daemon.listTabs() / daemon.switchTab(targetId) / daemon.newTab(url?) / daemon.current()
  • daemon.session(targetId) for raw CDP: session.call, session.callOnTarget, session.callBrowser, session.takeDialog
• require, fetch, JSON, Buffer, console, setTimeout, clearTimeout
• signal — AbortSignal
• onUpdate({ content: [{ type: 'text', text }] }) — progress callback
• ctx — ExtensionContext

Don't:

• Use scripts for one-off actions — call browser_* tools directly.
• Call browser_* tools from inside a script — sequence them as separate tool calls outside.