Idempotency

Networks fail. If a write request times out, you can't know whether DOOLAE did the work. Send an Idempotency-Key header, and retrying can never do it twice.

curl https://api.doolae.online/v1/bills \
  -H "Authorization: Bearer $DOOLAE_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: 9a8f3c1e-2b4d-4e6f-8a1b-3c5d7e9f0a2b" \
  -d '{"room_id": "room_…", "month": "2026-10"}'

Every POST, PATCH and DELETE endpoint accepts it. Use a new random value (a UUID) for each operation, and the same value when you retry that operation.

What happens

You send	You get
A new key	The request runs. Its response is stored for 24 hours.
The same key and the same request again	The stored response, unchanged, with `Idempotent-Replayed: true`. Nothing runs again.
The same key while the first request is still running	`409 idempotency_in_progress`. Retry after a second.
The same key with a different body, method or path	`422 idempotency_key_reused`.

Keys are scoped to your application and the account. Two applications, or two accounts, can't collide.
Responses 2xx to 4xx are stored. A 5xx is not, so you can simply retry.
If a request stopped half-way on DOOLAE's side, a retry after about 60 seconds runs it again. That is safe, because every write is all-or-nothing.
A key may be up to 255 printable ASCII characters (400 invalid_idempotency_key otherwise).

Built-in protection

Even without a key, some writes can't be duplicated:

Write	What stops a duplicate
`POST /v1/meter-readings`	One reading per room and month (`409 resource_exists` with the existing ID).
`POST /v1/bills`	One bill per room and month (`409 resource_exists`).
`POST /v1/rooms/{room_id}/tenant`	One tenant per room (`409 room_occupied`).
`POST /v1/properties/{property_id}/rooms`	Room numbers are unique within a property (`409 room_number_taken`).
LINE messages	Each message is delivered once even if DOOLAE retries it.

POST /v1/notifications, POST /v1/messages and POST /v1/properties have no such natural key: always send an Idempotency-Key with them.