# Server Utilities

Utilities available from `neutron`. These should generally only be used in `loader` and `action` functions.

## `redirect`

Throws a redirect response.

```tsx
import { redirect } from "@neutron-build/core";

export async function action() {
  throw redirect("/login");
}
```

## Response Helpers

Neutron uses standard [Response](https://developer.mozilla.org/en-US/docs/Web/API/Response) objects. You can construct them directly.

```tsx
export async function loader() {
  if (!found) {
    throw new Response("Not Found", { status: 404 });
  }
}
```

## Keeping code server-only

Two conventions keep server code out of the browser bundle:

### `.server.ts` files

Any module whose filename ends in `.server` (e.g. `db.server.ts`,
`auth.server.ts`) is **server-only**. Its imports are stripped from the
client build, so it is safe to use secrets, database drivers, or Node
built-ins there:

```ts
// src/lib/db.server.ts
import { Pool } from "pg";
export const db = new Pool({ connectionString: process.env.DATABASE_URL });
```

```tsx
// src/routes/users.tsx
import { db } from "../lib/db.server.ts"; // stripped from the client bundle

export async function loader() {
  return { users: (await db.query("SELECT * FROM users")).rows };
}
```

### Node built-ins in route modules

You can import Node built-ins (`node:fs`, `path`, `crypto`, …) directly in a
route module as long as you only use them in server exports (`loader`,
`action`, HTTP handlers). When Neutron builds the client half of the route it
removes those exports **and** their now-unused built-in imports, so they never
reach the browser:

```tsx
import { readFileSync } from "node:fs"; // removed from the client bundle

export const config = { mode: "app" };

export async function loader() {
  return { version: readFileSync("VERSION", "utf8") };
}

export default function Page({ data }) {
  return <p>Version {data.version}</p>;
}
```

Look-alike packages that are **not** built-ins (`fs-extra`, `path-browserify`)
are left untouched — only real Node built-ins are stripped.