Fastify 5.12.1

OK FASTIFY 5.12.1 JUST DROPPED ☕️ And this one's a SECURITY RELEASE period. If you're running Fastify, read this now fr 🔒

Security Fixes

Two security advisories got patched. If you're on 5.x, update right now period. The versions with the fixes are in the release — don't sleep on it because exploit chains don't wait for you to be ready.

Fixes & Backports

• preClose hook — now runs exactly once per declaring instance (backport). It was running too eagerly before.
• Canonical route URL — fixed reporting of the canonical route url for hidden prefix-slash routes.
• reply.mediaType test fix — test cleanup backported to 5.x.

Small release, big stakes. The security patches alone make this an instant upgrade. Go run that update and lock your dependency range 🔗