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:

• Check if daemon is running (.browser-ready file exists)

• If not, offer to start as background task

• Use browser-client.js commands to perform actions

• Report results back to user

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