b-open-io/chrome-cdp

Chrome CDP

Lightweight Chrome DevTools Protocol CLI. Connects directly via WebSocket — no Puppeteer, no extensions, instant connection, handles 100+ tabs. Operates on the user's live browser session with existing logins and state.

Prerequisites

1. Chrome with remote debugging enabled. If list fails with "Chrome remote debugging not enabled", run the enable command to open the settings page:

   bun ${SKILL_PATH}/scripts/cdp.ts enable
   

   Then tell the user: "I've opened Chrome's remote debugging settings. Please toggle the switch to enable it, then I'll try again."

2. Bun runtime (already available in this environment).

Auto-setup flow: Always try list first. If it fails, run enable and ask the user to toggle. Then retry list.

When to Use

Trigger on explicit user approval to:

• Read content from an authenticated page (logged-in GitHub, Linear, email, etc.)
• Click buttons, fill forms, or interact with a page the user has open
• Take screenshots of live pages
• Extract structured data from JavaScript-heavy SPAs
• Debug or inspect a running web application

Do NOT activate speculatively. The user must ask you to interact with Chrome.

Commands

All commands use bun ${SKILL_PATH}/scripts/cdp.ts. The <target> is a unique prefix of the targetId shown by list. Copy the prefix exactly as shown.

List open tabs

bun ${SKILL_PATH}/scripts/cdp.ts list

Always run list first to see available tabs and get target prefixes.

Read page structure (accessibility tree)

bun ${SKILL_PATH}/scripts/cdp.ts snap <target>

Returns a semantic tree of the page — roles, names, values. Best for understanding page structure without raw HTML noise.

Execute JavaScript

bun ${SKILL_PATH}/scripts/cdp.ts eval <target> "document.title"
bun ${SKILL_PATH}/scripts/cdp.ts eval <target> "document.querySelectorAll('h1').length"
bun ${SKILL_PATH}/scripts/cdp.ts eval <target> "[...document.querySelectorAll('a')].map(a => a.href).join('\\n')"

Runs in the page context — full DOM access, can call page functions, read variables.

Navigate

bun ${SKILL_PATH}/scripts/cdp.ts nav <target> "https://example.com"

Navigates and waits for page load (up to 30s).

Click element

bun ${SKILL_PATH}/scripts/cdp.ts click <target> "button.submit"
bun ${SKILL_PATH}/scripts/cdp.ts click <target> "[data-testid='login-btn']"

Type text

bun ${SKILL_PATH}/scripts/cdp.ts type <target> "Hello world"

Uses Input.insertText — works in cross-origin iframes where JS eval is blocked.

Screenshot

bun ${SKILL_PATH}/scripts/cdp.ts shot <target>

Saves to /tmp/screenshot.png.

Extract HTML

bun ${SKILL_PATH}/scripts/cdp.ts html <target>              # full page
bun ${SKILL_PATH}/scripts/cdp.ts html <target> ".sidebar"    # specific selector

Stop daemons

bun ${SKILL_PATH}/scripts/cdp.ts stop           # all daemons
bun ${SKILL_PATH}/scripts/cdp.ts stop <target>   # specific daemon

How It Works

1. Chrome writes a DevToolsActivePort file when remote debugging is enabled
2. The CLI reads this file to get the WebSocket URL
3. First access to a tab spawns a lightweight background daemon
4. Chrome shows an "Allow debugging" dialog once per tab — click Allow
5. Subsequent commands reuse the daemon silently (no more dialogs)
6. Daemons auto-terminate after 20 minutes of inactivity

Workflow Pattern

1. bun cdp.ts list                          # see what's open
2. bun cdp.ts snap 6BE827FA                 # understand the page
3. bun cdp.ts eval 6BE827FA "document.title" # extract specific data
4. bun cdp.ts click 6BE827FA ".btn-submit"  # interact

Safety

• Always confirm before clicking buttons that trigger irreversible actions (delete, send, purchase)
• Rate limit interactions — don't spam-click or rapid-fire requests
• Respect authentication — the user's live sessions are sensitive. Don't navigate away from pages without asking.
• The "Allow debugging" dialog is a security gate — the user controls which tabs are accessible