backend-patterns_skill

Overview

This skill packages battle-tested backend architecture patterns and practical guidance for Node.js, Express, and Next.js API routes. It focuses on API design, repository/service layers, database optimization, caching, error handling, auth, rate limiting, background jobs, and observability. Use it to design maintainable, performant server-side systems and to standardize common implementation patterns.

How this skill works

The skill inspects common server responsibilities and recommends concrete patterns: resource-based REST routing, repository and service separation, middleware composition, and cache-aside strategies with Redis. It highlights query optimization, N+1 prevention, transaction usage, structured logging, centralized error handling, and simple job/queue approaches. Each pattern includes implementation notes and code-level examples you can adapt to Node.js, Express, or Next.js API routes.

When to use it

• Designing or refactoring REST or GraphQL endpoints for clarity and consistency
• Separating business logic from data access using repository/service layers
• Optimizing database access to avoid N+1 queries and reduce payloads
• Adding caching, rate limiting, or background job processing
• Implementing authentication, role-based permissions, and secure token validation

Best practices

• Prefer resource-based routes and clear query parameters for filtering/pagination
• Select only needed columns and batch related queries to prevent N+1
• Keep middleware small and composable (auth, logging, rate limiting)
• Use cache-aside with TTLs and explicit invalidation for mutable resources
• Centralize errors and validation to return consistent responses and proper status codes

Example use cases

• Build a Markets API with repository + cached repository layers and Redis TTLs
• Wrap Next.js API routes with auth middleware that attaches user context
• Implement a vector-search service that uses embeddings, service-layer sorting, and batched DB fetches
• Add an exponential-backoff retry wrapper for unstable external APIs
• Queue indexing jobs to run asynchronously instead of blocking request handlers