backend-dev-guidelines

Backend Development Guidelines

Purpose

Establish consistency and best practices across backend services using modern Node.js/Express/TypeScript patterns.

Written for Node.js/Express/TypeScript with Prisma and Sentry. Different stack? Adapt the architectural principles - see CLAUDE_INTEGRATION_GUIDE.md in the repo root.

When to Use This Skill

Automatically activates when working on:

• Creating or modifying routes, endpoints, APIs
• Building controllers, services, repositories
• Implementing middleware (auth, validation, error handling)
• Database operations with Prisma
• Error tracking with Sentry
• Input validation with Zod
• Configuration management
• Backend testing and refactoring

---

Quick Start

New Backend Feature Checklist

• Route: Clean definition, delegate to controller
• Controller: Extend BaseController
• Service: Business logic with DI
• Repository: Database access (if complex)
• Validation: Zod schema
• Sentry: Error tracking
• Tests: Unit + integration tests
• Config: Use unifiedConfig

New Microservice Checklist

• Directory structure (see architecture-overview.md)
• instrument.ts for Sentry
• unifiedConfig setup
• BaseController class
• Middleware stack
• Error boundary
• Testing framework

---

Architecture Overview

Layered Architecture

HTTP Request
    ↓
Routes (routing only)
    ↓
Controllers (request handling)
    ↓
Services (business logic)
    ↓
Repositories (data access)
    ↓
Database (Prisma)

Key Principle: Each layer has ONE responsibility.

See architecture-overview.md for complete details.

---

Directory Structure

service/src/
├── config/              # UnifiedConfig
├── controllers/         # Request handlers
├── services/            # Business logic
├── repositories/        # Data access
├── routes/              # Route definitions
├── middleware/          # Express middleware
├── types/               # TypeScript types
├── validators/          # Zod schemas
├── utils/               # Utilities
├── tests/               # Tests
├── instrument.ts        # Sentry (FIRST IMPORT)
├── app.ts               # Express setup
└── server.ts            # HTTP server