Frontend

Grey Haven's comprehensive testing strategy - Vitest unit/integration/e2e for TypeScript, pytest markers for Python, >80% coverage requirement, fixture patterns, and Doppler for test environments. Use when writing tests, setting up test infrastructure, running tests, debugging test failures, improving coverage, configuring CI/CD, or when user mentions 'test', 'testing', 'pytest', 'vitest', 'coverage', 'TDD', 'test-driven development', 'unit test', 'integration test', 'e2e', 'end-to-end', 'test fixtures', 'mocking', 'test setup', 'CI testing'.

Fetches official documentation for external libraries and frameworks (React, Next.js, Prisma, FastAPI, Express, Tailwind, MongoDB, etc.) with 60-90% token savings via content-type filtering. Use this skill when implementing features using library APIs, debugging library-specific errors, troubleshooting configuration issues, installing or setting up frameworks, integrating third-party packages, upgrading between library versions, or looking up correct API patterns and best practices. Triggers automatically during coding work - fetch docs before writing library code to get correct patterns, not after guessing wrong.

Comprehensive performance analysis and optimization for algorithms (O(n²)→O(n)), databases (N+1 queries, indexes), React (memoization, virtual lists), bundles (code splitting), API caching, and memory leaks. 85%+ improvement rate. Use when application is slow, response times exceed SLA, high CPU/memory usage, performance budgets needed, or when user mentions 'performance', 'slow', 'optimization', 'bottleneck', 'speed up', 'latency', 'memory leak', or 'performance tuning'.

Generate production-ready project scaffolds for Grey Haven stack with Cloudflare Workers, React + TypeScript, Python + Pydantic, PlanetScale, proper structure, and configuration. Use when starting new projects, creating microservices, setting up monorepo workspaces, initializing projects, or when user mentions 'new project', 'project scaffold', 'project template', 'project setup', 'bootstrap project', 'project starter', or 'initialize project'.

Use when styling Rails views - Tailwind CSS utility-first framework and DaisyUI component library with theming

Systematic API design methodology with 6 validated patterns covering parameter categorization, safe refactoring, audit-first approach, automated validation, quality gates, and example-driven documentation. Use when designing new APIs, improving API consistency, implementing breaking change policies, or building API quality enforcement. Provides deterministic decision trees (5-tier parameter system), validation tool architecture, pre-commit hook patterns. Validated with 82.5% cross-domain transferability, 37.5% efficiency gains through audit-first refactoring.

Use when you have a spec or requirements for a multi-step task, before touching code

Browser automation using Playwright MCP. Navigate websites, fill forms, click elements, take screenshots, and extract data. Use for web browsing, form submission, web scraping, or UI testing. NOT for static content (use curl/wget).

Performs code review following team's quality assurance guidelines. Use when the user asks to "review code", "check this code", "리뷰해줘", "코드 리뷰", "코드 검토", "이 코드 봐줘", "이거 괜찮아?", "확인해줘", "문제 없어?", or after writing code when they want feedback on the changes just made.

Design and implement long-term memory systems for AI agents using vector stores, knowledge graphs, and hybrid approaches. Includes benchmarks and decision frameworks. Use when building persistent agent memory, implementing RAG, designing knowledge bases, or when user mentions 'memory', 'RAG', 'vector store', 'knowledge graph', 'long-term memory', 'retrieval', or 'embeddings'.

UI/UX design intelligence. 50 styles, 21 palettes, 50 font pairings, 20 charts, 8 stacks (React, Next.js, Vue, Svelte, SwiftUI, React Native, Flutter, Tailwind). Actions: plan, build, create, design, implement, review, fix, improve, optimize, enhance, refactor, check UI/UX code. Projects: website, landing page, dashboard, admin panel, e-commerce, SaaS, portfolio, blog, mobile app, .html, .tsx, .vue, .svelte. Elements: button, modal, navbar, sidebar, card, table, form, chart. Styles: glassmorphism, claymorphism, minimalism, brutalism, neumorphism, bento grid, dark mode, responsive, skeuomorphism, flat design. Topics: color palette, accessibility, animation, layout, typography, font pairing, spacing, hover, shadow, gradient.

Use when completing tasks, implementing major features, or before merging to verify work meets requirements

Turn the idea for a feature into a fully-formed PRD/design/specification and implementation-plan. Use in pre-implementation (idea-to-design) stages to make sure you understand the requirements and have a correct implementation plan before writing actual code.

프레젠테이션 슬라이드를 미려한 HTML로 디자인. 슬라이드 HTML 생성, 시각적 디자인, 레이아웃 구성이 필요할 때 사용.

Analyze dependencies for upgrade planning and migration. Use when user asks "upgrade to X", "migrate from X to Y", "what breaks if we upgrade", "iOS 17 migration", "React 18 upgrade", or planning framework/SDK upgrades.

TypeScript/JavaScript Test-Driven Development with Vitest, strict red-green-refactor methodology, React component testing, and comprehensive coverage patterns. Use when implementing TypeScript features with TDD, writing Vitest tests, testing React components, developing with test-first approach, or when user mentions 'TypeScript TDD', 'Vitest', 'React testing', 'JavaScript TDD', 'red-green-refactor', 'TypeScript unit tests', or 'test-driven TypeScript'.

Quickly understand a new codebase's architecture, tech stack, and patterns. Use when user asks "what is this project", "project overview", "how is this codebase structured", "what tech stack", or when onboarding to a new codebase.

HTML 슬라이드를 PowerPoint(PPTX) 파일로 변환. PPTX 생성, 편집, 썸네일 생성이 필요할 때 사용.

Apply Grey Haven's TanStack ecosystem patterns - Router file-based routing, Query data fetching with staleTime, and Start server functions. Use when building React applications with TanStack Start. Triggers: 'TanStack', 'TanStack Start', 'TanStack Query', 'TanStack Router', 'React Query', 'file-based routing', 'server functions'.

Creates production-grade, reusable skills that extend Claude's capabilities. This skill should be used when users want to create a new skill, improve an existing skill, or build domain-specific intelligence. Gathers context from codebase, conversation, and authentic sources before creating adaptable skills.