Browser Daemon

Browser Daemon - Persistent Browser Automation

Persistent browser daemon that keeps Chrome open and accepts commands via file-based IPC.

Quick Start

Start the daemon (once per session)

cd ~/.claude/skills/playwright-skill
node browser-daemon.js

Or ask: "Start the browser daemon in the background"

The browser window opens and stays open.

Send commands

Use absolute paths (cleaner, no directory changes):

# Navigate
~/.claude/skills/playwright-skill/browser-client.js navigate "http://localhost:8080/..."

# Execute JavaScript
~/.claude/skills/playwright-skill/browser-client.js exec "document.title"
~/.claude/skills/playwright-skill/browser-client.js exec "document.querySelectorAll('div').length"

# Console logs
~/.claude/skills/playwright-skill/browser-client.js console
~/.claude/skills/playwright-skill/browser-client.js console-clear

# Status
~/.claude/skills/playwright-skill/browser-client.js status

# Resize viewport
~/.claude/skills/playwright-skill/browser-client.js resize 1920 1080

Both scripts have shebangs and are executable, so they can be called directly.

Architecture

Claude (Bash tool)
    ↓
browser-client.js (writes .browser-command)
    ↓
browser-daemon.js (polls, executes, writes .browser-result)
    ↓
Chrome Browser (Playwright-controlled)

IPC Files:

• .browser-command - Command input (JSON)
• .browser-result - Command output (JSON)
• .browser-ready - Ready signal (exists when daemon is running)

Files created/deleted automatically during operation.

Commands

navigate

Navigate to URL and wait for page load.

node browser-client.js navigate "http://localhost:8080/page"

Returns: { success: true, url: string, title: string }

exec

Execute JavaScript in browser context.

node browser-client.js exec "document.querySelectorAll('div').length"

Returns: { success: true, result: any }

console

Get all captured console logs.

node browser-client.js console

Returns: { success: true, logs: [{ type, text, location }] }

console-clear

Clear console log buffer.

node browser-client.js console-clear

Returns: { success: true }

status

Check daemon status and current page info.

node browser-client.js status

Returns: { success: true, url, title, consoleLogsCount }

resize

Resize browser viewport.

node browser-client.js resize 1920 1080

Returns: { success: true, width, height }

Daemon Behavior

• Launches Chrome (not Chromium) for H.264 codec support
• Viewport set to full available screen size on startup
• Automatically captures all console output (log, warn, error, debug, pageerror)
• Polls for commands every 100ms
• Lazy restart: When browser is closed and command is sent, daemon detects closure, restarts browser, restores last URL, then executes command

Browser Configuration

chromium.launch({
  channel: 'chrome',      // Use Google Chrome, not Chromium
  headless: false,        // Visible window
  args: ['--start-maximized']
})

Important Quirks

Manual window resizing does NOT work:

• Playwright controls viewport independently from window
• Manually resizing browser window does NOT change viewport
• Window resize does NOT trigger JavaScript resize events
• Use resize command instead: node browser-client.js resize 1024 768

DevTools overlay:

• Opening DevTools does NOT resize viewport - overlays on top
• Does NOT trigger resize events
• Does NOT change window.innerWidth/Height

Viewport vs Window:

• window.innerWidth/Height - The viewport (controlled by Playwright)
• window.outerWidth/Height - The window size
• Only viewport can be changed via resize command

Use Cases

Interactive development: Keep browser open while testing changes, reload and check console without manual interaction.

Debugging console logs: Track down log sources with automatic source location capture.

Inspecting page state: Query DOM, check element counts, inspect computed styles via JavaScript execution.

Testing workflows: Automate multi-step browser interactions (navigate, fill forms, submit, check results).

Troubleshooting

Daemon not responding:

ls ~/.claude/skills/playwright-skill/.browser-ready
cd ~/.claude/skills/playwright-skill && node browser-daemon.js

Commands timing out:

• Check if browser window is still open
• Kill daemon and restart
• Clean up stuck files: rm -f .browser-command .browser-result

Browser window closed:

• Kill daemon (Ctrl+C)
• Restart: node browser-daemon.js
• Or send any command - lazy restart will trigger automatically

Setup (First Time)

cd ~/.claude/skills/playwright-skill
npm install

This installs Playwright and downloads Chrome browser.

Advanced Capabilities

See META_COMMANDS.md for comprehensive reference of Playwright's meta-level capabilities beyond basic testing:

• Page events (console, network, dialogs, workers, frames, lifecycle)
• Content capture (screenshots, PDFs, HTML, video)
• Network control (interception, mocking, HAR replay, WebSockets)
• Script injection and Node.js function exposure
• Performance metrics and garbage collection
• Chrome DevTools Protocol (CDP) access for low-level browser control
• Browser context events and meta methods

Integration Notes

When user requests browser interaction:

1. Check if daemon is running (.browser-ready file exists)
2. If not, offer to start as background task
3. Use browser-client.js commands to perform actions
4. Report results back to user

User can request additional features - the codebase is straightforward and well-documented for extensions.