> ## Documentation Index
> Fetch the complete documentation index at: https://opensandbox-oc-s-762ac928075c46d2828bcb22.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Create Reservation

Commit capacity across one or more 15-minute UTC intervals in a single
atomic write. The result is one reservation event with a server-generated
`reservationId` covering all intervals in the request. See
[Reserving capacity](/reserved-capacity/reserving) for the full write
contract.

Send an `Idempotency-Key` header so retries return the original result.
Same key with a different body returns `idempotency_key_conflict`.

Reservations are non-refundable — there is no cancellation, modification,
or transfer.

<ParamField body="intervals" type="array" required>
  One entry per 15-minute interval to reserve.
</ParamField>

<ParamField body="intervals[].startsAt" type="string" required>
  Interval start. RFC 3339, UTC, aligned to 15 minutes (`:00`, `:15`, `:30`, `:45`).
</ParamField>

<ParamField body="intervals[].endsAt" type="string" required>
  Interval end. Must equal `startsAt + 15 minutes`. Multi-interval spans are rejected.
</ParamField>

<ParamField body="intervals[].capacityGb" type="integer" required>
  Positive multiple of 4 (the grain is 1 GB-hour = 4 GB × 15 min). Other
  values are rejected.
</ParamField>

<ResponseExample>
  ```json 200 theme={null}
  {
    "reservationId": "9f67b8f7-7b91-4d2d-b1cb-19d0d0a14562",
    "createdAt": "2026-04-28T18:00:05Z",
    "intervals": [
      {
        "startsAt": "2026-04-29T02:00:00Z",
        "endsAt":   "2026-04-29T02:15:00Z",
        "capacityGb": 16
      },
      {
        "startsAt": "2026-04-29T02:15:00Z",
        "endsAt":   "2026-04-29T02:30:00Z",
        "capacityGb": 16
      }
    ]
  }
  ```

  ```json 409 capacity_not_available theme={null}
  {
    "error": "capacity_not_available",
    "intervals": [
      {
        "startsAt": "2026-04-29T02:00:00Z",
        "requestedGb": 80,
        "reservableGb": 28,
        "reason": "insufficient_capacity"
      }
    ]
  }
  ```
</ResponseExample>