Quickstart: use idempotency keys on write requests

Generate one key per operation

The key identifies a logical action, not a physical request. Generate it once when the user submits, and reuse it if the network fails and you retry:

const key = crypto.randomUUID();
async function submit() {
  return withRetry(() => fetch(`${BASE}/enquiries`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', 'Idempotency-Key': key },
    body: JSON.stringify(enquiry),
  }));
}

What the server does with it

On the first request with a given key the API processes it normally and stores the result. A repeat with the same key returns that stored result instead of doing the work again — so a timed-out retry is completely safe.

Scope and lifetime

Keys are scoped per endpoint and remembered for a window long enough to cover retries. Never reuse a key for a genuinely different submission, and never share one key across two users.