browser-automation

Este extracto es una copia guardada durante la revisión. La fuente externa contiene la versión completa y actual.

---
name: "browser-automation"
description: "Use when the user asks to automate browser tasks, scrape websites, fill forms, capture screenshots, extract structured data from web pages, or build web automation workflows. NOT for testing — use playwright-pro for that."
---

# Browser Automation - POWERFUL

## Overview

The Browser Automation skill provides comprehensive tools and knowledge for building production-grade web automation workflows using Playwright. This skill covers data extraction, form filling, screenshot capture, session management, and anti-detection patterns for reliable browser automation at scale.

**When to use this skill:**
- Scraping structured data from websites (tables, listings, search results)
- Automating multi-step browser workflows (login, fill forms, download files)
- Capturing screenshots or PDFs of web pages
- Extracting data from SPAs and JavaScript-heavy sites
- Building repeatable browser-based data pipelines

**When NOT to use this skill:**
- Writing browser tests or E2E test suites — use **playwright-pro** instead
- Testing API endpoints — use **api-test-suite-builder** instead
- Load testing or performance benchmarking — use **performance-profiler** instead

**Why Playwright over Selenium or Puppeteer:**
- **Auto-wait built in** — no explicit `sleep()` or `waitForElement()` needed for most actions
- **Multi-browser from one API** — Chromium, Firefox, WebKit with zero config changes
- **Network interception** — block ads, mock responses, capture API calls natively
- **Browser contexts** — isolated sessions without spinning up new browser instances
- **Codegen** — `playwright codegen` records your actions and generates scripts
- **Async-first** — Python async/await for high-throughput scraping

## Core Competencies

### 1. Web Scraping Patterns

**Selector priority (most to least reliable):**
1. `data-testid`, `data-id`, or custom data attributes — stable across redesigns
2. `#id` selectors — unique but may change between deploys
3. Semantic selectors: `article`, `nav`, `main`, `section` — resilient to CSS changes
4. Class-based: `.product-card`, `.price` — brittle if classes are generated (e.g., CSS modules)
5. Positional: `nth-child()`, `nth-of-type()` — last resort, breaks on layout changes

Use XPath only when CSS cannot express the relationship (e.g., ancestor traversal, text-based selection).

**Pagination strategies:** next-button, URL-based (`?page=N`), infinite scroll, load-more button. See [data_extraction_recipes.md](references/data_extraction_recipes.md) for complete pagination handlers and scroll patterns.

### 2. Form Filling & Multi-Step Workflows

Break multi-step forms into discrete functions per step. Each function fills fields, clicks "Next"/"Continue", and waits for the next step to load (URL change or DOM element).

Key patterns: login flows, multi-page forms, file uploads (including drag-and-drop zones), native and custom dropdown handling. See [playwright_browser_api.md](references/playwright_browser_api.md) for complete API reference on `fill()`, `select_option()`, `set_input_files()`, and `expect_file_chooser()`.

### 3. Screenshot & PDF Capture

- **Full page:** `await page.screenshot(path="full.png", full_page=True)`
- **Element:** `await page.locator("div.chart").screenshot(path="chart.png")`
- **PDF (Chromium only):** `await page.pdf(path="out.pdf", format="A4", print_background=True)`
- **Visual regression:** Take screenshots at known states, store baselines in version control with naming: `{page}_{viewport}_{state}.png`

See [playwright_browser_api.md](references/playwright_browser_api.md) for full screenshot/PDF options.

### 4. Structured Data Extraction

Core extraction patterns:
- **Tables to JSON** — Extract `<thead>` headers and `<tbody>` rows into dictionaries
- **Listings to arrays** — Map repeating card elements using a field-selector map (supports `::attr()` for attributes)
- **Nested/threaded data** — Recursive extraction for comments with replies, ca