# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

Code Crispies is an interactive CSS/Tailwind learning platform built with pure JavaScript (ES Modules) and Vite. Users complete lessons by writing CSS or Tailwind code that passes validation rules.

## Commands

```bash
npm start          # Start dev server at http://localhost:1312
npm run build      # Production build to dist/
npm run test       # Run tests once
npm run test.watch # Run tests in watch mode
npm run test.coverage # Run tests with coverage report
npm run format     # Format source files with Prettier
npm run format.lessons # Format lesson JSON files
```

## Architecture

### Core Components

- **LessonEngine** (`src/impl/LessonEngine.js`): Single source of truth for lesson state, progress tracking, and code validation. Manages user code application to preview iframes and persists progress to localStorage.

- **Validator** (`src/helpers/validator.js`): Validates user code against lesson requirements. Supports validation types: `contains`, `contains_class`, `not_contains`, `regex`, `property_value`, `syntax`, `custom`.

- **Lesson Config** (`src/config/lessons.js`): Loads and validates lesson modules from JSON. Modules are imported statically and stored in `moduleStore`.

### Data Flow

1. Lesson JSON files define modules with lessons, each containing `previewHTML`, `validations`, and other metadata
2. `LessonEngine` loads modules and tracks user progress per lesson
3. User code is applied to an iframe preview and validated against lesson rules
4. Progress is persisted to `localStorage` under `codeCrispies.progress` and `codeCrispies.userCode`

### Lesson Structure

Lessons are JSON files in `lessons/` following the schema in `schemas/code-crispies-module-schema.json`. Each module has:
- `mode`: "css" or "tailwind"
- `difficulty`: "beginner", "intermediate", or "advanced"
- `lessons[]`: Array of lessons with validations

For Tailwind mode, user classes are injected via `{{USER_CLASSES}}` placeholder in `previewHTML`.

### Testing

Tests use Vitest with jsdom environment. Setup in `tests/setup.js` includes DOM testing library matchers. Test files are in `tests/unit/`.

## Git Commits

- Do NOT add co-authoring lines to commit messages
- Follow conventional commit format (feat:, fix:, refactor:, docs:, etc.)