# Svelte Runtime Environment Variables — repStore()

> Access runtime environment variables in Svelte with repStore() and repSecureStore(). Native readable stores with lazy SSE hot reload subscriptions.

Source: https://rep-protocol.dev/frameworks/svelte/

## Installation

```bash
npm install @rep-protocol/svelte @rep-protocol/sdk
```

## Basic usage

```svelte
<script lang="ts">
  import { repStore, repSecureStore } from '@rep-protocol/svelte';

  // PUBLIC tier — synchronous, updates on hot reload
  const apiUrl = repStore('API_URL', 'http://localhost:3000');
  const flags = repStore('FEATURE_FLAGS', '');

  // SENSITIVE tier — starts as null, resolves after decryption
  const analyticsKey = repSecureStore('ANALYTICS_KEY');
</script>

<p>API: {$apiUrl}</p>
<p>Analytics: {$analyticsKey ?? 'loading...'}</p>
```

## `repStore(key, defaultValue?)`

Reads a **PUBLIC** tier variable as a Svelte `Readable<string | undefined>`.

```typescript
const value: Readable<string | undefined> = repStore('API_URL');
const value: Readable<string | undefined> = repStore('API_URL', 'fallback');
```

- Synchronous initial value from the REP payload
- Automatically updates when the variable changes via hot reload
- **Lazy SSE:** the connection is established only when there is at least one subscriber, and closed when all subscribers unsubscribe

## `repSecureStore(key)`

Reads a **SENSITIVE** tier variable as a `Readable<string | null>`.

```typescript
const value: Readable<string | null> = repSecureStore('ANALYTICS_KEY');
```

- Starts as `null`
- Resolves to the decrypted value once the session key fetch completes
- Errors are swallowed (the SDK logs them); the store stays `null`

> **Caution**
>
> `repSecureStore` does **not** support hot reload. Changes to sensitive variables require a page reload.

## Hot reload

`repStore` subscribes to the SSE stream lazily — only when there's at least one subscriber. The store value updates automatically. When the last subscriber unsubscribes, the SSE connection is closed.

## Development mode

  **Default values**

  ```typescript
  const apiUrl = repStore('API_URL', 'http://localhost:3000');
  ```

  **Mock payload**

  Add to your `index.html`:
  ```html
  <script id="__rep__" type="application/json">
  {"public":{"API_URL":"http://localhost:3000"},"_meta":{"version":"0.1.0","injected_at":"2026-01-01T00:00:00Z","integrity":"hmac-sha256:dev","ttl":0}}
  </script>
  ```

## Requirements

- Svelte >= 4 or Svelte 5
- `@rep-protocol/sdk` as a peer dependency

For the full API reference, see [Svelte Adapter Reference](/reference/adapters/svelte/).