API Development with Fastify

Quick Guide: Use Fastify for high-performance Node.js REST APIs with built-in JSON Schema validation and powerful plugin encapsulation. Use @fastify/type-provider-typebox for end-to-end type safety (both Type and TypeBoxTypeProvider re-exported from it). Wrap shared plugins with fastify-plugin to expose decorators. Always define response schemas for serialization performance and data leak prevention.

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CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST use withTypeProvider<>() for type-safe request/response handling)

(You MUST wrap shared plugins with fastify-plugin to expose decorators to parent scope)

(You MUST define response schemas to enable fast-json-stringify optimization)

(You MUST use named constants for HTTP status codes - never raw numbers)