page-agent/AGENTS.md

Instructions for coding assistants

Project Overview

This is a dual-architecture project with two separate parts:

1. Core Library (src/) - Pure JavaScript/TypeScript AI agent library for browser DOM automation
2. Demo&docs Website (pages/) - React documentation and landing page

Development Commands

Core Commands

npm start                    # Start React website development server
npm run build                # Build both library AND website
npm run build:lib            # Build pure JS library only (src/ → dist/lib/)
npm run build:lib:watch      # Library development with auto-rebuild
npm run lint                 # ESLint with TypeScript strict rules

Architecture & Critical Patterns

Dual Build System

• Website build: vite.config.js → React SPA with hash routing → dist/
• Library build: vite.lib.config.js → UMD/ES modules → dist/lib/
• Entry points: src/entry.ts (library), pages/main.tsx (website)

Module Boundaries (Critical)

• Core library (src/): NEVER import from pages/ - must remain pure JavaScript
• Website (pages/): CAN import from src/ via @/ alias for demos
• Import aliases: @/ → src/, @pages/ → pages/

DOM Pipeline

1. DOM Extraction: Convert live DOM to FlatDomTree via src/dom/dom_tree/
2. Dehydration: DOM tree → simplified text for LLM processing
3. LLM Processing: AI model returns action plans
4. Indexed Operations: Map LLM responses back to specific DOM elements

Event Bus Communication

Use src/utils/bus.ts for decoupled PageAgent ↔ UI communication:

// Emit from PageAgent
getEventBus().emit('panel:show')
getEventBus().emit('panel:update', { status: 'thinking' })

// Listen in UI components
getEventBus().on('panel:show', () => panel.show())

Hash Routing Requirement

Uses wouter with useHashLocation for static hosting:

<Router hook={useHashLocation}>  // Always hash-based routes

CDN Auto-Injection Pattern

Library auto-initializes when injected via script tag:

<script src="page-agent.js?model=gpt-4"></script>

Query params configure PageAgentConfig automatically in src/entry.ts.

File Organization

Core Library (src/)

• entry.ts - CDN/UMD entry point with auto-initialization
• PageAgent.ts - Main AI agent class orchestrating DOM operations
• tools/ - Agent tool implementations for web actions
• ui/ - UI components (Panel, SimulatorMask) with CSS modules
• utils/bus.ts - Type-safe event bus for decoupled communication
• patches/ - Framework-specific optimizations (React, Antd compatibility)
• llms/ - LLM integration and communication layer
• dom/ - HTML serialization and page analysis utilities
• config/ - Configuration constants and settings

Website (pages/)

• main.tsx - Site entry with hash routing setup
• router.tsx - Manual route definitions (requires explicit registration)
• components/DocsLayout.tsx - Navigation structure (hardcoded nav items)
• docs/[section]/[topic]/page.tsx - Documentation pages
• test-pages/ - Library integration test pages

Adding New Features

New Documentation Page

1. Create pages/docs/<section>/<slug>/page.tsx
2. Add route to pages/router.tsx with <Header /> + <DocsLayout> wrapper
3. Add navigation item to DocsLayout.tsx

New Agent Tool

1. Implement under src/tools/
2. Export via src/tools/index.ts
3. Wire into PageAgent.ts if needed

New UI Component

1. Create in src/ui/ with colocated CSS modules
2. Use event bus for PageAgent communication
3. Test via pages/test-pages/

Code Standards

TypeScript

• Explicit typing for exported/public APIs
• ESLint relaxes some unsafe rules for rapid iteration

CSS & Styling

• Prefer Tailwind CSS over custom CSS
• Custom CSS variables for theme gradients in src/index.css
• Dark mode support via dark: classes
• CSS modules for component-specific styles

Import Organization

• External libraries first
• Internal modules (@/, @pages/)
• Relative imports last
• Blank lines between groups

Critical Files to Understand

• pages/router.tsx - Central routing definition (manual registration required)
• pages/components/DocsLayout.tsx - Navigation structure
• src/PageAgent.ts - Core AI agent class with DOM manipulation
• src/dom/dom_tree/index.js - DOM extraction engine
• src/utils/bus.ts - Type-safe event bus system
• src/entry.ts - Library entry point for CDN usage
• vite.config.js / vite.lib.config.js - Dual build configuration

Debugging Common Issues

Blank Documentation Pages

1. Verify route exists in pages/router.tsx
2. Check component import path
3. Verify CSS isn't hiding content (check dark mode classes)
4. Test with minimal component first

Library Integration Issues

1. Check dist/lib/page-agent.umd.js builds correctly
2. Test CDN injection with query params
3. Verify event bus communications are properly typed
4. Use pages/test-pages/ for isolated testing