Implement Backend Development Patterns

Catalogs backend architecture patterns for Node.js, Express, and Next.js API routes across nine areas: RESTful API design (resource-based URLs, query-param filtering/sorting/pagination), the repository pattern for abstracting data access, a service layer for business logic, middleware (an auth-checking withAuth wrapper), database query optimization (selecting only needed columns, avoiding N+1 queries via batch fetch, wrapping multi-table writes in a Supabase RPC transaction), Redis caching (a CachedMarketRepository decorator and a cache-aside function with a 300-second TTL), centralized error handling (an ApiError class plus retry-with-exponential-backoff), JWT-based auth and role-based access control, an in-memory sliding-window rate limiter, a simple background job queue, and structured JSON logging.

GET    /api/markets                 # List resources
GET    /api/markets/:id             # Get single resource
POST   /api/markets                 # Create resource
PUT    /api/markets/:id             # Replace resource
PATCH  /api/markets/:id             # Update resource
DELETE /api/markets/:id             # Delete resource

Reach for this skill when building or hardening a Node.js/Express/Next.js API that needs proven patterns for structuring endpoints, isolating data access, caching hot reads, handling errors consistently, authenticating requests, or protecting against abuse - each backed by a runnable TypeScript example. It is not a framework or library itself - it is a pattern reference. The sample code assumes Supabase, Redis, and jsonwebtoken, so adapting patterns to a different stack (a different ORM, session store, or auth provider) means translating the specifics yourself.

Each pattern is a self-contained TypeScript snippet meant to be read and adapted rather than run as-is. The repository pattern defines a MarketRepository interface (findAll, findById, create, update, delete) implemented against Supabase; the service layer's MarketService.searchMarkets() takes a query string and limit, generates an embedding, runs a vector search, and returns matched records sorted by similarity. The rate limiter's checkLimit(identifier, maxRequests, windowMs) returns a boolean; the retry helper fetchWithRetry(fn, maxRetries) re-invokes an async function up to maxRetries times with exponential backoff before rethrowing. API route handlers return Next.js NextResponse.json() responses with explicit HTTP status codes: 400 for validation failures via z.ZodError, 401 for auth failures, 403 for insufficient permissions, 429 for rate-limit breaches, and 500 for unexpected errors.

Examples are built against Supabase (supabase.from(...).select()/.rpc()) for the database and repository/transaction patterns, Redis for the caching layer, jsonwebtoken for JWT verification, and Next.js API route conventions (NextResponse, NextApiHandler) for request and response handling.

Backend and full-stack developers working in Node.js, Express, or Next.js who want reference implementations - not a library to install - for API structure, data-access layering, caching, error handling, auth and authorization, rate limiting, background job queues, and structured logging.