Client-side fetch HTTP methods match handler exports

A client calls fetch('/api/posts', { method: 'DELETE' }) but the route handler at app/api/posts/route.ts only exports GET and POST. Next.js and every other App Router framework respond with HTTP 405 Method Not Allowed — the server is reachable, the path resolves, but the method is refused. This is a reference-integrity failure that neither the bundler nor tsc can catch because HTTP methods are stringly-typed, and the error only surfaces when the user clicks the delete button.

Add the missing method export to the route handler so the server accepts the request shape the client sends. Open the route file and export a named function per method:

// app/api/posts/route.ts
export async function GET() { /* ... */ }
export async function POST() { /* ... */ }
export async function DELETE() { /* ... */ }

Or change the client to use a method the handler already exports.