[Feature] Browser automation tool (web interaction and data extraction)

[Wan-ZL]

Description

Give Genesis the ability to interact with websites: fetch structured data, fill forms, extract content, and take screenshots. This transforms Genesis from "AI that talks about the web" to "AI that uses the web."

Why This Matters

• Most user requests ultimately involve web interaction
• Current web_fetch tool only gets raw HTML -- cannot interact with JavaScript-rendered content
• Browser automation enables: price comparison, form filling, data extraction, screenshot capture
• Competitors (OpenClaw, Lindy) offer browser automation as a core skill

Acceptance Criteria

• BrowserService: assistant/server/services/browser.py
• Uses Playwright for headless browser automation
• Tools registered: browse_url, extract_content, take_screenshot, fill_form
• browse_url: Navigate to URL, wait for content, return text/structured data
• extract_content: CSS selector-based content extraction from a page
• take_screenshot: Capture page screenshot, store in memory/files/
• fill_form: Fill form fields by selector and submit
• All tools require SYSTEM permission level
• Resource limits: max 30 second page load, max 5 concurrent browsers
• Sandbox: Playwright runs in headless mode with restricted permissions
• URL allowlist/blocklist configurable via settings
• At least 12 tests (mock browser interactions)
• Documentation: assistant/docs/BROWSER_AUTOMATION.md

Technical Notes

• Playwright is preferred over Selenium (faster, better API, async support)
• Headless mode only (no visible browser window)
• Browser context isolated per request (no cookie leakage)
• Screenshots stored with metadata for future reference
• Consider page content caching to reduce redundant requests

Security Considerations

• SYSTEM permission required (browser can access local network)
• URL filtering to prevent accessing sensitive internal services
• No credential auto-fill (user must explicitly provide form data)
• Rate limiting to prevent abuse
• Browser sandbox prevents filesystem access

Priority Rationale

MEDIUM: Powerful capability but complex to implement safely. Should be built after the core accessibility and memory features are solid.

Phase

Phase 8: Always-On Partner

Dependencies

• None (uses existing permission system)

Related

• Phase 8 ADR: planner_iteration/decisions/ADR-004-phase8-always-on-partner.md