---

name: authentication-logic description: Guide to using Better Auth for client and server-side authentication.

Authentication Logic

Overview

We use Better Auth (better-auth) for identifying users.

Config

• Client: lib/auth-client.ts exports authClient.
• Server: lib/auth.ts exports auth.

Client-Side Usage

Use authClient for signing in, signing out, and checking session state in Client Components.

Copyimport { authClient } from "@/lib/auth-client";

// Sign In
await authClient.signIn.email({
  email,
  password,
});

// Social Sign In
await authClient.signIn.social({
  provider: "google",
  callbackURL: "/onboarding", 
});

// Sign Out
await authClient.signOut();

Server-Side Usage

Use auth.api.getSession for protecting API routes or Server Actions.

Copyimport { auth } from "@/lib/auth";
import { headers } from "next/headers";

const session = await auth.api.getSession({
  headers: await headers()
});

if (!session) {
  return new Response("Unauthorized", { status: 401 });
}

AuthBar Component

• Located at textbook/src/components/AuthBar/index.tsx.
• Displays user avatar or login button.
• Fetches session from /api/auth/session (Next.js API route proxying Better Auth).