alexander-kastil/go-playwright

Playwright Go Automation Expert

Overview

This skill provides a comprehensive framework for writing high-performance, production-grade browser automation scripts using github.com/playwright-community/playwright-go. It enforces architectural best practices (contexts over instances), robust error handling, structured logging (Zap), and advanced human-emulation techniques to bypass anti-bot systems.

When to Use This Skill

• Use when the user asks to "scrape," "automate," or "test" a website using Go.
• Use when the target site has complex dynamic content (SPA, React, Vue) requiring a real browser.
• Use when the user mentions "stealth," "avoiding detection," "cloudflare," or "human-like" behavior.
• Use when debugging existing Playwright scripts.

Safety & Risk

Risk Level: 🔵 Safe

• Sandboxed Execution: Browser contexts are isolated; they do not persist data to the host machine unless explicitly saved.
• Resource Management: Designed to close browsers and contexts via defer to prevent memory leaks.
• No External State-Change: Default behavior is read-only (scraping/testing) unless the script is explicitly designed to submit forms or modify data.

Limitations

• Environment Dependencies: Requires Playwright drivers and browsers to be installed (go run github.com/playwright-community/playwright-go/cmd/playwright@latest install --with-deps).
• Resource Intensity: Launching full browser instances (even headless) consumes significant RAM/CPU. Use single-browser/multi-context architecture.
• Bot Detection: While this skill includes stealth techniques, extremely strict anti-bot systems (e.g., rigorous Cloudflare settings) may still detect automation.
• CAPTCHAs: Does not include built-in CAPTCHA solving capabilities.

Strategic Implementation Guidelines

1. Architecture: Contexts vs. Browsers

CRITICAL: Never launch a new Browser instance for every task.

• Pattern: Launch the Browser once (singleton). Create a new BrowserContext for each distinct session or task.
• Why: Contexts are lightweight and created in milliseconds. Browsers take seconds to launch.
• Isolation: Contexts provide complete isolation (cookies, cache, storage) without the overhead of a new process.

2. Logging & Observability

• Library: Use go.uber.org/zap exclusively.
• Rule: Do not use fmt.Println.
• Modes:
  • Dev: zap.NewDevelopment() (Console friendly)
  • Prod: zap.NewProduction() (JSON structured)
• Traceability: Log every navigation, click, and input with context fields (e.g., logger.Info("clicking button", zap.String("selector", sel))).

3. Error Handling & Stability

• Graceful Shutdown: Always use defer to close Pages, Contexts, and Browsers.
• Panic Recovery: Wrap critical automation routines in a safe runner that recovers panics and logs the stack trace.
• Timeouts: Never rely on default timeouts. Set explicit timeouts (e.g., playwright.PageClickOptions{Timeout: playwright.Float(5000)}).

4. Stealth & Human-Like Behavior

To bypass anti-bot systems (Cloudflare, Akamai), the generated code must imitate human physiology:

• Non-Linear Mouse Movement: Never teleport the mouse. Implement a helper that moves the mouse along a Bezier curve with random jitter.
• Input Latency: never use Fill(). Use Type() with random delays between keystrokes (50ms–200ms).
• Viewport Randomization: Randomize the viewport size slightly (e.g., 1920x1080 ± 15px) to avoid fingerprinting.
• Behavioral Noise: Randomly scroll, focus/unfocus the window, or hover over irrelevant elements ("idling") during long waits.
• User-Agent: Rotate User-Agents for every new Context.

5. Documentation Usage

• Primary Source: Rely on your internal knowledge of the API first to save tokens.
• Fallback: Refer to the official docs playwright-go documentation ONLY if:
  • You encounter an unknown error.
  • You need to implement complex network interception or authentication flows.
  • The API has changed significantly.

Resources

• resources/implementation-playbook.md for detailed code examples and implementation patterns.

Summary Checklist for Agent

• Is Debug Mode on? -> Headless=false, SlowMo=100+.
• Is it a new user identity? -> NewContext, apply new Proxy, rotate User-Agent.
• Is the action critical? -> Wrap in SafeAction with Zap logging.
• Is the target guarded (Cloudflare/Akamai)? -> Enable HumanType, BezierMouse, and Stealth Scripts.