Plugins

Better Auth plugin

Wire Better Auth into Reion with @reionjs/better-auth, route handlers, and optional ctx.auth helpers.

Authentication is provided by @reionjs/better-auth, which connects Better Auth to Reion's HTTP stack.

Install

From your app root:

npx reion add -p @reionjs/better-auth
yarn dlx reion add -p @reionjs/better-auth
bunx reion add -p @reionjs/better-auth
pnpm exec reion add -p @reionjs/better-auth

The setup script will:

  • Prompt for a database option: Simple (SQLite file), PostgreSQL, MySQL, or Manual (in-memory adapter until you plug in your own database).
  • Install better-auth and, when you did not pass --skip-install, the driver packages for your choice (for example better-sqlite3 and @types/better-sqlite3 for SQLite).
  • Scaffold src/plugins/better-auth.ts and a catch-all auth route at src/router/api/auth/[[...params]]/route.ts.
  • Register the plugin in reion.config.ts (including adding plugins: [] if it was missing).

Use reion add --skip-install only if you install dependencies yourself; you may then need to run the package manager commands the setup prints for database drivers.

Add @reionjs/better-auth and better-auth:

npm install @reionjs/better-auth better-auth
yarn add @reionjs/better-auth better-auth
bun add @reionjs/better-auth better-auth
pnpm add @reionjs/better-auth better-auth

Add your database client the same way (for example better-sqlite3 and @types/better-sqlite3, or pg, mysql2, etc.).

Then add the auth route, plugin module, and reion.config.ts entries yourself, following the examples below.

Auth HTTP route

The generated route forwards all methods to Better Auth's Node handler and opts into the raw body so Better Auth can read the request correctly:

src/router/api/auth/[[...params]]/route.ts
import { createBetterAuthRouteHandler } from "@reionjs/better-auth";
import { auth } from "@/plugins/better-auth.js";

const handleAuth = createBetterAuthRouteHandler(auth);
export const RAW_BODY = true;

export const GET = handleAuth;
export const POST = handleAuth;
export const PUT = handleAuth;
export const PATCH = handleAuth;
export const DELETE = handleAuth;
export const OPTIONS = handleAuth;

Mount path follows your folder structure (here: /api/auth/*). Adjust the router path if you need a different prefix.

Plugin registration

Your better-auth instance and plugin export usually live in src/plugins/better-auth.ts. Register the plugin in reion.config.ts:

reion.config.ts
import { betterAuthPlugin } from "./src/plugins/better-auth";

export default {
  plugins: [betterAuthPlugin],
};

(Exact import path may differ if setup used a different layout.)

BetterAuthPlugin options

BetterAuthPlugin({
  auth, // required: return value of betterAuth({ ... })
  attachToContext?: boolean; // default true
});
  • auth — your Better Auth app instance.
  • attachToContext — when true (default), the plugin sets ctx.auth and ctx.authSession() on each request so non-auth routes can read the session. Set to false if you only want the /api/auth routes and no context helpers.

Types for ctx.auth / ctx.authSession come from the package's module augmentation; importing BetterAuthPlugin (or anything) from @reionjs/better-auth loads that augmentation.

Session in a normal route

src/router/api/me/route.ts
export async function GET(ctx) {
  const session = await ctx.authSession();
  if (!session) {
    ctx.res.status(401);
    return { error: "Unauthorized" };
  }
  ctx.res.status(200);
  return { user: session.user };
}

Use ctx.auth.api for other Better Auth server APIs as needed.

Cron plugin

Use @reionjs/cron for scheduled tasks under appDir/cron and manual runs via ctx.schedule().

On this page

Install
Auth HTTP route
Plugin registration
BetterAuthPlugin options
Session in a normal route