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

# Errors & Retries

> Typed errors, automatic retries, and timeouts.

## Error hierarchy

Everything the SDK throws extends `CestoError`. Server responses become typed `APIError`
subclasses; transport problems become connection errors. All classes are exposed on the
`Cesto` client for `instanceof` checks.

```ts theme={null}
import { Cesto } from '@cesto/sdk';

try {
  await cesto.products.get('missing-slug');
} catch (err) {
  if (err instanceof Cesto.NotFoundError) {
    // 404
  } else if (err instanceof Cesto.AuthenticationError) {
    // 401 — invalid / missing / revoked key
  } else if (err instanceof Cesto.RateLimitError) {
    // 429 — err.retryAfter (ms)
  } else if (err instanceof Cesto.APIConnectionError) {
    // network failure or timeout
  } else {
    throw err;
  }
}
```

| Class                       | When                                  |
| --------------------------- | ------------------------------------- |
| `BadRequestError`           | 400                                   |
| `AuthenticationError`       | 401 — invalid / missing / revoked key |
| `PermissionDeniedError`     | 403                                   |
| `NotFoundError`             | 404                                   |
| `ConflictError`             | 409                                   |
| `UnprocessableEntityError`  | 422                                   |
| `RateLimitError`            | 429 — carries `retryAfter` (ms)       |
| `InternalServerError`       | 5xx                                   |
| `APIConnectionError`        | network failure                       |
| `APIConnectionTimeoutError` | request exceeded `timeout`            |
| `APIUserAbortError`         | your `AbortSignal` fired              |

Every `APIError` carries `status`, `code`, `requestId`, and `details` from the API — useful
when reporting an issue.

## Automatic retries

Transient failures (408, 409, 429, 5xx, connection errors, and timeouts) are retried automatically with
exponential backoff and jitter, honoring the `Retry-After` header. Tune with `maxRetries`
(default `2`), or disable per request with `{ maxRetries: 0 }`.

## Timeouts & cancellation

Each request times out after `timeout` ms (default 60s), throwing `APIConnectionTimeoutError`.
Pass an `AbortSignal` to cancel a request yourself:

```ts theme={null}
const controller = new AbortController();
const promise = cesto.products.list({}, { signal: controller.signal });
controller.abort(); // → APIUserAbortError
```