Fastify
Your agent now builds Fastify backends against best practices maintained by Fastify co-creator Matteo Collina — routes, plugins, JSON Schema validation, lifecycle hooks, Pino logging, security headers, and the full request lifecycle.
What it installs
| Artifact | Path (in your project) | Purpose |
|---|---|---|
| Stack ref | (inherits typescript bundle) | TypeScript coding style, patterns, testing, and security rules |
| Skill | .agents/skills/fastify-best-practices/ | Protocol the agent follows on Fastify work — sourced from mcollina/skills |
| Rule | .claude/rules/fastify.md | Always-loaded pointer: triggers on any Fastify route, plugin, hook, or app.ts / server.ts work |
How it works
Fastify rewards schema-first thinking and punishes Express-style improvisation. The skill encodes the canonical patterns: define routes with JSON Schema for validation and serialization speedup, encapsulate feature slices as plugins, use onRequest / preHandler / onSend hooks correctly, configure Pino for structured logs, set security headers, and integrate TypeScript via strip types.
The rule loads a pointer into every session, so the agent consults the skill before writing a route, plugin, hook, or auth/CORS config — no explicit invocation needed.
Setup
No env vars or external accounts required. The skill is fetched from GitHub during harness-kit add via npx skills add.
Pairs well with
postgresql— async DB patterns fit naturally with Fastify's async route handlersredis— session / cache integration via Fastify pluginscode-review-gates— enforce schema-first + plugin-encapsulation patterns on every commit