api-development

SKILL.md

API Development

You are an expert in API development with Go and NestJS.

Go API Development with Standard Library (1.22+)

Core Principles

Always use the latest stable version of Go (1.22 or newer)

Use the net/http package for HTTP handling

Leverage the standard library before reaching for external dependencies

HTTP Handling

Use http.NewServeMux() for routing (Go 1.22+ enhanced patterns)

Implement proper HTTP method handling

Return appropriate status codes for all responses

Handle request body parsing safely

Error Handling

Implement comprehensive error handling

Return meaningful error messages to clients

Log errors with sufficient context

Use custom error types for API-specific failures

Input Validation

Validate all incoming request data

Sanitize inputs to prevent injection attacks

Return clear validation error messages

Reject requests with invalid data early

Middleware

Implement middleware for cross-cutting concerns

Use middleware for logging and request tracing

Apply authentication middleware to protected routes

Implement rate limiting as middleware

Clean NestJS APIs with TypeScript

Code Standards

Use English for all code and documentation

Always declare the type of each variable and function

Avoid using any type; prefer explicit types

Enable strict TypeScript compiler options

Naming Conventions

Use PascalCase for classes and interfaces

Use camelCase for variables, functions, and methods

Use SCREAMING_SNAKE_CASE for constants

Name files using kebab-case

Modular Architecture

Implement one module per domain

Keep modules focused and cohesive

Export only necessary components

Use barrel files for clean imports

DTOs and Validation

Use DTOs for all inputs and outputs

Validate with class-validator decorators

Transform data with class-transformer

Keep DTOs separate from domain entities

Controller Guidelines

Keep controllers thin

Delegate business logic to services

Use proper HTTP decorators

Implement consistent response formats

Common Module

Implement shared reusable code:

Configs - Shared configuration utilities

Decorators - Custom decorators

Guards - Authentication and authorization

Filters - Exception filters

Interceptors - Request/response interceptors

Pipes - Validation and transformation

Security Best Practices

Implement authentication guards

Use role-based authorization

Validate all inputs at boundaries

Sanitize outputs to prevent XSS