Browser Automation

CodeBuddy integrates Playwright for headless browser automation, enabling tasks like testing web UIs, scraping data, filling forms, and taking screenshots. The browser tool wraps an MCP Playwright server with multiple security layers — SSRF prevention, input sanitization, JavaScript execution restrictions, and audit logging.

Setup

Browser automation requires Playwright with Chromium:

npx playwright install chromium

Supported actions

Action	Parameter	Description
`navigate`	`url`	Open a URL in the browser
`click`	`ref`	Click an element by accessibility reference
`type`	`ref`, `text`	Type text into an input field
`select_option`	`ref`, `value`	Select an option from a dropdown
`hover`	`ref`	Hover over an element
`press_key`	`key`	Press a keyboard key
`screenshot`	—	Capture the current page as an image
`snapshot`	—	Get the accessibility tree (structured page content)
`evaluate`	`expression`	Execute JavaScript in the browser context
`wait`	`time`	Wait for a specified duration
`tabNew`	`url?`	Open a new browser tab
`tabClose`	—	Close the current tab
`tabSwitch`	—	Switch between open tabs
`tabList`	—	List all open tabs
`goBack`	—	Navigate back in history
`goForward`	—	Navigate forward in history

Security layers

SSRF protection

The NavigationGuard prevents Server-Side Request Forgery by blocking navigation to internal networks:

Blocked addresses: RFC 1918 private ranges (10.x, 172.16-31.x, 192.168.x), loopback (127.x, ::1), link-local (169.254.x), IPv6 unique-local (fc00::/7)
Encoding detection: Catches octal, decimal, and hex IP obfuscation attempts
Post-navigation check: Verifies DNS resolution didn’t redirect to a private IP after the page loaded
Protocol restriction: Only http: and https: URLs are allowed
Length limits: Hostname ≤ 253 chars, pathname ≤ 2,048 chars, total URL ≤ 8,192 chars

Input sanitization

The InputGuard validates all inputs before they reach the browser:

Element references: Maximum 512 characters, shell injection characters stripped
Key inputs: Must match ^[A-Za-z0-9+\-_]{1,64}$
No raw user input is passed to evaluate() without sanitization

JavaScript restrictions

The evaluate action blocks dangerous patterns:

fetch() and XMLHttpRequest — prevents data exfiltration
eval() and Function() — prevents arbitrary code execution
localStorage, sessionStorage, document.cookie — prevents credential theft
WebSocket — prevents covert channels

Example usage

Open localhost:3000, take a screenshot of the login page, and check if the form is accessible

Navigate to our staging site, fill in the registration form with test data, and verify the success page

Open the dashboard, click the "Export" button, and verify the CSV download contains the expected columns

Configuration

{
  "codebuddy.browser.headless": true,
  "codebuddy.browser.timeout": 30000,
  "codebuddy.browser.viewport": { "width": 1280, "height": 720 }
}

Set headless to false to watch browser automation in real time.