# Environment Variables

Neutron uses Vite's environment variable handling.

## `.env` Files

Place `.env` files in your project root.

```
# .env
DATABASE_URL="postgresql://user:pass@localhost:5432/db"
PUBLIC_API_KEY="12345"
```

## Server vs Client

-   **Server**: Variables are available via `process.env` (Node) or specific context providers (Cloudflare).
    ```ts
    export async function loader() {
      // Safe to use secrets here
      const db = connect(process.env.DATABASE_URL);
    }
    ```

-   **Client**: Only variables prefixed with `PUBLIC_` (or `VITE_`) are exposed to the client.
    ```ts
    console.log(import.meta.env.PUBLIC_API_KEY);
    ```

**Warning**: Never access private secrets (like DB passwords) in code that runs on the client (components), even if you think you are "hiding" it. Only access them in `loader` or `action` functions.