> ## 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.

# Configuration

> Client options and per-request overrides.

## Client options

```ts theme={null}
new Cesto({
  apiKey: 'cesto_sk_…',       // required (or CESTO_API_KEY env)
  environment: 'PRODUCTION',  // 'PRODUCTION' | 'BETA' — default 'PRODUCTION'
  timeout: 60_000,            // per-request timeout in ms — default 60s
  maxRetries: 2,              // automatic retries on transient errors — default 2
  fetch: customFetch,         // optional custom fetch implementation
});
```

<ParamField path="apiKey" type="string">
  Secret API key. Falls back to `process.env.CESTO_API_KEY`. Required.
</ParamField>

<ParamField path="environment" type="'PRODUCTION' | 'BETA'" default="PRODUCTION">
  Which backend to target: `PRODUCTION` → `backend.cesto.co`, `BETA` → `dev.backend.cesto.co`.
  See [Authentication](/sdk/authentication#environments).
</ParamField>

<ParamField path="timeout" type="number" default="60000">
  Per-request timeout in milliseconds.
</ParamField>

<ParamField path="maxRetries" type="number" default="2">
  Max automatic retries on transient failures (408, 409, 429, 5xx, network errors, timeouts).
</ParamField>

<ParamField path="fetch" type="typeof fetch">
  Custom fetch implementation (e.g. `undici`). Defaults to the global `fetch`.
</ParamField>

## Per-request options

Every method accepts an options object as its last argument to override transport behavior
for a single call:

```ts theme={null}
await cesto.products.list(
  { category: 'defi' },
  { timeout: 5_000, maxRetries: 0, signal: controller.signal },
);
```

<ParamField path="timeout" type="number">
  Override the client timeout for this request.
</ParamField>

<ParamField path="maxRetries" type="number">
  Override retries for this request (e.g. `0` to disable).
</ParamField>

<ParamField path="signal" type="AbortSignal">
  Cancel the request; composed with the internal timeout.
</ParamField>