types.d.ts

import NextAuth, { type DefaultSession } from "next-auth";

declare module "next-auth" {
  /**
   * The shape of the user object returned in the OAuth providers' `profile` callback,
   * or the second parameter of the `session` callback, when using a database.
   */
  interface User {}
  /**
   * The shape of the account object returned in the OAuth providers' `account` callback,
   * Usually contains information about the provider being used, like OAuth tokens (`access_token`, etc).
   */
  interface Account {}

  /**
   * Returned by `useSession`, `auth`, contains information about the active session.
   */
  interface Session {
    user: {
      admin: boolean;
    } & DefaultSession["user"];
  }
}

export const { auth, handlers } = NextAuth({
  callbacks: {
    session({ session, token, user }) {
      return {
        ...session,
        user: {
          ...session.user,
          admin: user.admin,
        },
      };
    },
  },
});