chrome-cdp

Adapted from `pasky/chrome-cdp-skill` at commit ffea76a24b0471663ddd9d9f24335bbc442b6266 (MIT).

Chrome CDP

Lightweight Chrome DevTools Protocol CLI. Connects directly via WebSocket — no Puppeteer, works with 100+ tabs, instant connection. Resolve SKILL_DIR to this file's parent directory.

Prerequisites

• Chrome (or Chromium, Brave, Edge, Vivaldi) with remote debugging enabled: open chrome://inspect/#remote-debugging and toggle the switch
• Node.js 22+ (uses built-in WebSocket)
• If your browser's DevToolsActivePort is in a non-standard location, set CDP_PORT_FILE to its full path

Commands

All commands use node "$SKILL_DIR/scripts/cdp.mjs". The <target> is a unique targetId prefix from list; copy the full prefix shown in the list output (for example 6BE827FA). The CLI rejects ambiguous prefixes.

List open pages

node "$SKILL_DIR/scripts/cdp.mjs" list

Take a screenshot

node "$SKILL_DIR/scripts/cdp.mjs" shot <target> [file]    # default: screenshot-<target>.png in runtime dir

Captures the viewport only. Scroll first with eval if you need content below the fold. Output includes the page's DPR and coordinate conversion hint (see Coordinates below).

Accessibility tree snapshot

node "$SKILL_DIR/scripts/cdp.mjs" snap <target>

Evaluate JavaScript

node "$SKILL_DIR/scripts/cdp.mjs" eval <target> <expr>

Watch out: avoid index-based selection (querySelectorAll(...)[i]) across multiple eval calls when the DOM can change between them (e.g. after clicking Ignore, card indices shift). Collect all data in one eval or use stable selectors.

Other commands

node "$SKILL_DIR/scripts/cdp.mjs" html    <target> [selector]   # full page or element HTML
node "$SKILL_DIR/scripts/cdp.mjs" nav     <target> <url>         # navigate and wait for load
node "$SKILL_DIR/scripts/cdp.mjs" net     <target>               # resource timing entries
node "$SKILL_DIR/scripts/cdp.mjs" click   <target> <selector>    # click element by CSS selector
node "$SKILL_DIR/scripts/cdp.mjs" clickxy <target> <x> <y>       # click at CSS pixel coords
node "$SKILL_DIR/scripts/cdp.mjs" type    <target> <text>         # Input.insertText at current focus; works in cross-origin iframes unlike eval
node "$SKILL_DIR/scripts/cdp.mjs" loadall <target> <selector> [ms]  # click "load more" until gone (default 1500ms between clicks)
node "$SKILL_DIR/scripts/cdp.mjs" evalraw <target> <method> [json]  # raw CDP command passthrough
node "$SKILL_DIR/scripts/cdp.mjs" open    [url]                  # open new tab (each triggers Allow prompt)
node "$SKILL_DIR/scripts/cdp.mjs" stop    [target]               # stop daemon(s)

Coordinates

shot saves an image at native resolution: image pixels = CSS pixels × DPR. CDP Input events (clickxy etc.) take CSS pixels.

CSS px = screenshot image px / DPR

shot prints the DPR for the current page. Typical Retina (DPR=2): divide screenshot coords by 2.

Tips

• Prefer snap --compact over html for page structure.
• Use type (not eval) to enter text in cross-origin iframes — click/clickxy to focus first, then type.
• Chrome shows an "Allow debugging" modal once per tab on first access. A background daemon keeps the session alive so subsequent commands need no further approval. Daemons auto-exit after 20 minutes of inactivity.