Build, configure, and deploy Nitro v3 applications using correct APIs and patterns.

Step 1: Classify the request

Request type	Read first
API surface, handler signatures, imports, config options	`references/api-surface.md`
Setup, routing, caching, storage, plugins, frameworks, common patterns	`references/common-use-cases.md`
Build failures, runtime errors, deployment issues, migration from v2	`references/troubleshooting-workarounds.md`

Load only the reference(s) matching the request. If the task spans categories, load relevant files.

Step 2: Apply core guardrails

Import defineHandler from "nitro", not defineEventHandler (v2 API).
Import config helpers from subpaths: "nitro/config", "nitro/cache", "nitro/storage", "nitro/database", "nitro/runtime-config", "nitro/types".
Use web standard event.req (Request) for body/headers — not v2 utilities like readBody or getHeader.
Never return from middleware unless intentionally terminating the request.
Only GET/HEAD requests are cached by defineCachedHandler; other methods bypass automatically.