Idempotent requests

A dropped connection should never double-book. Send an Idempotency-Key header on a create request, and a retry with the same key replays the first response instead of creating a second resource.

How it works

Generate a unique key per logical operation (a UUID works well) and send it on the POST that creates an order or booking.

curl -X POST https://api.hermeseus.com/v3/HAPI/flights/orders \
  -H "Authorization: Bearer $ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: 5f2b8c1a-3e4d-4a6b-9c7e-1d2f3a4b5c6d" \
  -d '{ … }'

If you repeat the request with the same key, the original response is returned again, with an Idempotency-Replayed: true header, and no new order is created.

Where to use it

Use an idempotency key on every request that creates or mutates an order or booking: creating an order, requesting ticket issuance, confirming, cancelling, or refunding. Reads and searches do not need one.