[β Read the full CLAUDE.md file](claude/.claude/CLAUDE.md)
CLAUDE.md is a living document that defines development principles, patterns, and anti-patterns. It transforms abstract concepts into actionable decision frameworks.
Core Philosophy
- TDD is non-negotiable - Every line of production code must be test-driven
- Behavior over implementation - Tests verify what code does, not how it does it
- Immutability by default - Pure functions and immutable data structures
- Schema-first with nuance - Runtime validation at trust boundaries, types for internal logic
- Semantic refactoring - Abstract based on meaning, not structure
- Explicit documentation - Capture learnings while context is fresh
What Makes It Different
Unlike typical style guides, CLAUDE.md provides:
- Decision frameworks - Concrete questions to answer before taking action
- Priority classifications - Objective severity levels (Critical/High/Nice/Skip)
- Quality gates - Verifiable checklists before commits
- Anti-pattern catalogs - Side-by-side good/bad examples
- Git verification methods - How to audit compliance retrospectively
Key Sections
| Section | What It Provides | Detailed Patterns |
|---------|-----------------|-------------------|
| Testing Principles | Behavior-driven testing, 100% coverage strategy, factory patterns | [β skills/testing](claude/.claude/skills/testing/SKILL.md) |
| Mutation Testing | Test effectiveness verification, mutation operators, weak test detection | [β skills/mutation-testing](claude/.claude/skills/mutation-testing/SKILL.md) |
| Test Design Review | Dave Farley's 8 properties evaluation, Farley Score calculation, test quality assessment | [β skills/test-design-reviewer](claude/.claude/skills/test-design-reviewer/SKILL.md) |
| Front-End Testing | DOM Testing Library patterns, accessibility-first queries, userEvent best practices (framework-agnostic) | [β skills/front-end-testing](claude/.claude/skills/front-end-testing/SKILL.md) |
| React Testing | React Testing Library patterns for components, hooks, context, and forms | [β skills/react-testing](claude/.claude/skills/react-testing/SKILL.md) |
| TypeScript Guidelines | Schema-first decision framework, type vs interface clarity, immutability patterns | [β skills/typescript-strict](claude/.claude/skills/typescript-strict/SKILL.md) |
| TDD Process | RED-GREEN-REFACTOR cycle, quality gates, anti-patterns | [β skills/tdd](claude/.claude/skills/tdd/SKILL.md) |
| Refactoring | Priority classification, semantic vs structural framework, DRY decision tree | [β skills/refactoring](claude/.claude/skills/refactoring/SKILL.md) |
| Functional Programming | Immutability violations catalog, pure functions, composition patterns | [β skills/functional](claude/.claude/skills/functional/SKILL.md) |
| Expectations | Learning capture guidance, documentation templates, quality criteria | [β skills/expectations](claude/.claude/skills/expectations/SKILL.md) |
| Planning | Small increments, three-document model (PLAN/WIP/LEARNINGS), commit approval | [β skills/planning](claude/.claude/skills/planning/SKILL.md) |
| Web Quality Audit | Comprehensive Lighthouse-based quality review across all categories | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
| Performance | Loading speed, runtime efficiency, resource optimization | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
| Core Web Vitals | LCP, INP, CLS specific optimizations | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
| Accessibility | WCAG compliance, screen reader support, keyboard navigation | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
| SEO | Search engine optimization, crawlability, structured data | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
| Best Practices | Security, modern APIs, code quality patterns | [β web-quality-skills](https://github.com/addyosmani/web-quality-skills) |
---