Join the waitlist.

The seams, part by part

Pick a part. On the left is the entire seam this app wrote to wire it; on the right, the contract invariantthat seam leans on. That's the deal — the part guarantees the invariant, the app writes the seam, nothing in parts/ is touched.

// proxy.ts — Next 16's renamed middleware (Node runtime)
const limiter = rateLimitMiddleware({
  rule: { limit: 5, windowSeconds: 60 },
});

export async function proxy(request: NextRequest) {
  const limited = await limiter(request);  // 429, or null to pass
  return limited ?? NextResponse.next();
}

export const config = { matcher: "/api/join" };

Flip the vendor in one command

Switching Resend → Postmark is a partkit upgrade, not a rewrite. The vendored adapter and the env line change; not one seam line moves. Captured from a real run:

Proof: only the seams

Attested bill of materials

Rendered live from parts.lock — every part pinned by content hash, with its conformance attestation.

Vendored from registry.partkit.dev via the published CLI (no --registry flag). dev:unsigned = local dev attestation; production re-issues signed ones in CI. partkit.dev →