> ## Documentation Index
> Fetch the complete documentation index at: https://docs.layerx1.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Response headers.

> The API keeps its header surface small and stable: which model served you, where your request window stands, and — when you're asked to slow down — exactly how long to wait.

## On every response

| Header                           | Example            | Meaning                                                                                                                                                                                                          |
| -------------------------------- | ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `x1-model`                       | `lx1-gpt-oss-120b` | The model that served this request — always the catalog id you asked for.                                                                                                                                        |
| `x-ratelimit-limit-requests`     | `1000`             | Your plan's requests-per-minute limit.                                                                                                                                                                           |
| `x-ratelimit-remaining-requests` | `997`              | Requests left in the current window.                                                                                                                                                                             |
| `x-ratelimit-reset-requests`     | `42`               | Seconds until the window fully resets.                                                                                                                                                                           |
| `x1-allowance-limit`             | `200.00`           | Your plan's monthly included usage, measured in list-price USD.                                                                                                                                                  |
| `x1-allowance-remaining`         | `142.3120`         | Included usage left this month (USD) — the live figure the cap is enforced against. At zero it is a hard stop: requests return `429 allowance_exhausted` until reset or upgrade. Throttle as it approaches zero. |
| `x1-allowance-reset`             | `1209600s`         | Seconds until the monthly allowance resets.                                                                                                                                                                      |

```http title="Example response headers" theme={null}
x1-model: lx1-gpt-oss-120b
x-ratelimit-limit-requests: 1000
x-ratelimit-remaining-requests: 997
x-ratelimit-reset-requests: 42
x1-allowance-limit: 200.00
x1-allowance-remaining: 142.3120
x1-allowance-reset: 1209600s
```

The `x-ratelimit-*` trio lets a client pace itself instead of discovering the limit by
hitting it — throttle proactively as `remaining` approaches zero. Per-plan limits are
published on [Plans & limits](/plans).

## On 429 responses

| Header         | Example     | Meaning                                                                                                                                                             |
| -------------- | ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `retry-after`  | `12`        | Seconds to wait before retrying. Present on every 429 — a short pause on a rate limit, the seconds to month-end on an exhausted allowance.                          |
| `x1-allowance` | `exhausted` | Present only when the 429 is the monthly allowance (type `allowance_exhausted`), so clients can tell it apart from a transient rate limit without parsing the body. |

Honor it exactly; the value is computed, not a guess. The retry recipe (and which statuses
to retry at all) is on [Errors](/errors).

<Note>
  This is the complete customer-visible header surface. Anything else you may observe is
  not part of the API contract and can change without notice — build only against the
  headers on this page.
</Note>