Development

Native iOS features in Expo React Native apps. Use when implementing camera, push notifications, haptics, permissions, device sensors, or other native APIs in Expo.

React Native authentication patterns for Expo apps. Use when implementing login flows, Google/Apple sign-in, token management, session handling, or debugging auth issues in Expo/React Native.

Async/await correctness in React Native with Zustand. Use when debugging race conditions, missing awaits, floating promises, or async timing issues in Expo/React Native apps.

Zustand state management patterns for React. Use when working with Zustand stores, debugging state timing issues, or implementing async actions. Works for both React web and React Native.

Testing patterns for React with Jest and React Testing Library. Use when writing tests, mocking modules, testing Zustand stores, or debugging test failures in React web applications.

Complex multi-step operations in React. Use when implementing flows with multiple async steps, state machine patterns, or debugging flow ordering issues. Works for both React web and React Native.

Performance optimization for React web applications. Use when optimizing renders, implementing virtualization, memoizing components, or debugging performance issues.

Logging, error messages, and debugging patterns for React. Use when adding logging, designing error messages, debugging production issues, or improving code observability. Works for both React web and React Native.

Async/await correctness in React with Zustand. Use when debugging race conditions, missing awaits, floating promises, or async timing issues. Works for both React web and React Native.

Pydantic v2 patterns for validation and serialization. Use when creating schemas, validating data, or working with request/response models.

Observability patterns for Python backends. Use when adding logging, metrics, tracing, or debugging production issues.

FastAPI patterns for API design. Use when creating endpoints, handling dependencies, error handling, or working with OpenAPI schemas.

Async/await patterns for FastAPI and SQLAlchemy. Use when working with async code, database sessions, concurrent operations, or debugging async issues in Python.

Alembic migration patterns for PostgreSQL. Use when creating migrations, reviewing autogenerated migrations, or handling schema changes safely.

Building and deploying Expo React Native apps to iOS. Use when configuring EAS Build, submitting to TestFlight, App Store deployment, managing certificates, or troubleshooting build issues.

Comprehensive audit of Expo/React Native app API integration layer. Use when asked to: (1) Review API interactions, auth handling, or token management, (2) Find hardcoded data or screens bypassing API, (3) Verify user interactions properly sync to backend, (4) Analyze offline behavior and caching, (5) Audit Orval/OpenAPI code generation, (6) Check for API security issues. Supports TanStack Query, Zustand, axios, Expo Router, expo-secure-store, and expo-constants patterns.

GraphQL queries, mutations, and code generation patterns. Use when creating GraphQL operations, working with Apollo Client, or generating types.

Formik form handling with validation patterns. Use when building forms, implementing validation, or handling form submission.

**Use MCP repo-map tools when:** - Searching for symbols by name pattern (faster than Grep) - Getting all symbols in a file (faster than Read + parsing)

Enforces strict waterfall development workflow with phase gates. Use when (1) features.yml exists in project root, (2) user asks to implement/develop/build a feature, (3) user explicitly requests waterfall workflow. Creates features.yml if missing when invoked.

Guide for breaking changes into logical, atomic commits using interactive staging. Use when committing changes that span multiple concerns, when needing to stage parts of files (hunks), when asked to create well-organized commit history, or when changes should be split into multiple commits.

Format git commit messages combining Conventional Commits summary lines with Linux kernel-style bodies. Use when writing, reviewing, or formatting commit messages.

A type-safe, Redis-backed caching library for Remix applications with SSE-based real-time invalidation, stale-while-revalidate, pattern matching, and automatic React revalidation. Use when working with Remix caching, Redis, cache invalidation, implementing caching strategies, or real-time data synchronization in Remix apps.

Guides diagnosis and resolution when problems occur. Use when user mentions 動かない, エラーが出た, 壊れた, うまくいかない, broken, doesn't work, error. Do NOT load for: 正常なビルド, 新機能実装, レビュー.