backend-patterns

backend-patterns is a code-convention and architecture reference skill for building scalable server-side applications with Node.js, Express, and Next.js API routes. It solves the recurring problem of inconsistent, hard-to-maintain backend code by giving the agent a curated set of proven patterns to apply when designing endpoints, structuring data access, and optimizing database interaction. The guidance is delivered as annotated TypeScript examples that explicitly contrast good and bad approaches.

The skill activates around concrete backend tasks: designing REST or GraphQL endpoints, implementing repository/service/controller layers, preventing N+1 queries, adding indexing and connection pooling, and building middleware for auth, logging, and rate limiting. It documents resource-based RESTful URL conventions, the repository pattern (with a Supabase implementation example), a service layer that separates business logic from data access, an auth middleware wrapper, query optimization (selecting only needed columns), N+1 batch-fetch prevention, transaction patterns using Supabase RPC/plpgsql functions, Redis and cache-aside caching strategies, and a centralized ApiError-based error handler.

It is aimed at backend and full-stack developers working in TypeScript-first Node/Next.js stacks, particularly those using Supabase or Redis. Typical use cases include reviewing or scaffolding an API layer, refactoring data-access code to a repository pattern, adding a caching layer, or eliminating query performance problems. The content originates from the ECC project and reflects that codebase's conventions (e.g., a markets/positions domain), so examples are illustrative patterns rather than a general framework.