# Initialization (/docs/sdk/initialization)



The `init()` call on `@layers/client` / `@layers/react-native` takes a
`LayersConfig` object. Source of truth: the published TypeScript
definitions in [`@layers/client`](https://www.npmjs.com/package/@layers/client?activeTab=code).

## Supported fields [#supported-fields]

| Field          | Type                                         | Default                 | Notes                                                                                                                                                  |
| -------------- | -------------------------------------------- | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `appId`        | string                                       | required                | From Project → Layers SDK.                                                                                                                             |
| `apiKey`       | string                                       | required (by type)      | Currently ignored server-side; pass any non-empty string. The `X-Api-Key` header is accepted but not validated.                                        |
| `environment`  | `'development' \| 'staging' \| 'production'` | required                | Debug builds → `development`; release → `production`. All three ingest to the same prod backend; the value is persisted with each event for filtering. |
| `appUserId`    | string \| undefined                          | —                       | Initial user ID; same as calling `setAppUserId` after `init`.                                                                                          |
| `enableDebug`  | boolean                                      | `false`                 | Verbose console logging.                                                                                                                               |
| `baseUrl`      | string                                       | `https://in.layers.com` | Override for [custom domain](/docs/sdk/custom-domain).                                                                                                 |
| `queueOptions` | object                                       | see below               | Controls batching, retries, flush.                                                                                                                     |
| `queueStorage` | `QueueStorage \| null`                       | platform default        | Custom queue-persistence implementation (React Native defaults to AsyncStorage; web defaults to localStorage). Pass `null` to disable persistence.     |

### `queueOptions` [#queueoptions]

| Field                                  | Default | Notes                                        |
| -------------------------------------- | ------- | -------------------------------------------- |
| `flushIntervalMs`                      | —       | How often to flush pending events.           |
| `maxQueueSize`                         | —       | Maximum queued events before a forced flush. |
| `maxItemAgeMs`                         | —       | Drop events older than this before flushing. |
| `requestTimeoutMs`                     | —       | Per-request timeout.                         |
| `maxRetries`                           | —       | Retry budget per batch.                      |
| `baseRetryDelayMs` / `maxRetryDelayMs` | —       | Exponential backoff bounds.                  |

Defaults are sane for most apps — only override if you have a specific
reason.

## Fields that are NOT supported today [#fields-that-are-not-supported-today]

Previous docs mentioned `flushInterval` (seconds), `maxBatchSize`,
`defaultConsent`, `enableATT`, `kidsMode`, `testEventCode`,
`setSampling`, `name` (for multi-instance). None of those are on the
`LayersConfig` type. They will land if / when the feature ships.

## Consent [#consent]

Consent is managed via `setConsent({ advertising, analytics })` at
runtime, not via an init-time default. See [Consent](/docs/sdk/consent).

## Remote config [#remote-config]

After `init()`, the SDK fetches `/config` from the ingest host and
applies server-side settings (event allowlists, sampling, killswitches).
That config is cached with ETag + `cache-control`. You don't call
`/config` directly — `init()` handles it.