AI Coding Skills for Fastify

Review API design against REST best practices and internal consistency. Audits naming conventions, HTTP method semantics, status code correctness, pagination and filtering patterns, error response format, versioning strategy, rate limiting, idempotency keys, HATEOAS links, and content negotiation. Works with Express, Fastify, Hono, Flask, Django REST, Spring, Rails, Gin, and any HTTP API framework. Use when you need to review an API, audit REST endpoints, check API consistency, fix HTTP status codes, add pagination, or prepare an API for public release.

Generate OpenAPI 3.1 documentation from your API codebase. Auto-detects Express, Fastify, NestJS, Django, FastAPI, Flask, Rails, Spring, Go, and more. Extracts routes, request/response schemas, auth requirements, and validation rules. Sets up interactive docs with Swagger UI, Redoc, or Scalar. Use when you need API documentation, OpenAPI spec, Swagger docs, endpoint reference, or REST API docs.

Scaffold a production-ready backend REST API -- generate a complete server project with routes, controllers, service layer, repository pattern, database models with migrations, JWT authentication with RBAC, request validation, global error handling with custom error classes, structured JSON logging, rate limiting, CORS, health check endpoint, OpenAPI/Swagger documentation, multi-stage Dockerfile, and docker-compose with PostgreSQL and Redis. Supports Fastify 5, NestJS, Express, FastAPI, Django REST, Gin, Chi, Echo, and Rails -- auto-detects framework from context. Build a backend, create an API, generate server, scaffold REST service, new backend project.

Generate integration tests for APIs, databases, and external services. Auto-detects backend stack (Express, Fastify, NestJS, Django, FastAPI, Rails, Go), ORM (Prisma, TypeORM, SQLAlchemy, GORM), and database (PostgreSQL, MongoDB, Firestore), then creates tests covering endpoint CRUD, auth flows, DB transactions, and external service failures with proper fixtures and mocks. Self-heals failing tests up to 3 iterations. Use when you need to test API endpoints end-to-end, verify database operations, test service interactions, or validate auth and error handling.

Generate consumer-driven contract tests for APIs. Auto-detects framework (Express, Fastify, NestJS, Django, FastAPI, Go), selects Pact, OpenAPI validation, or schema snapshots, verifies backward compatibility, catches breaking changes before deploy, and configures CI verification. Use when you need to validate API schemas, prevent breaking changes, verify backward compatibility, or set up consumer-driven contracts.

Guidelines for building high-performance APIs with Fastify and TypeScript, covering validation, Prisma integration, and testing best practices

Optimize NestJS throughput with Fastify adapter, singleton scope enforcement, compression, and query projections. Use when switching to Fastify, diagnosing request-scoped bottlenecks, or profiling API overhead. (triggers: main.ts, FastifyAdapter, compression, SINGLETON, REQUEST scope)

Scaffold a production-ready financial services API -- generate a complete fintech backend with Plaid bank account linking and transaction sync, ACH/wire/card payment processing with payment orchestration, double-entry bookkeeping ledger with immutable entries and balance caching, KYC identity verification workflow with progressive tiers and document upload, idempotent request handling with deduplication windows, HMAC-signed outbound webhooks with retry and exponential backoff, append-only audit logging for compliance, multi-currency support with integer minor-unit arithmetic, and field-level encryption for sensitive data. Supports Fastify 5, NestJS, Express, FastAPI, Django REST, and Gin. Build a fintech API, create payment backend, scaffold banking API, financial services backend, money transfer service, neobank API, lending platform.

Migrate between frameworks, libraries, or language versions — React class→hooks, JavaScript→TypeScript, Express→Fastify, and more. Preserves behavior with tests.