> ## Documentation Index
> Fetch the complete documentation index at: https://stackonfire.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> How Cascade handles authentication and authorization.

## Next Auth

<Tip>
  Cascade is based on T3 app meaning that it uses NextAuth.js under the hood. Docs are [here](https://create.t3.gg/en/usage/next-auth).
</Tip>

This documentation is a brief overview of what is put on top of NextAuth.js to make it work with Cascade. We will focus on interesting parts!

We extend the `Session` object with some additional types to make it work with Cascade. We need to add `role` and `planId` to the user object.

```ts theme={null}

declare module "next-auth" {
  interface Session extends DefaultSession {
    user: {
      id: string;
      planId: string | null;
      role: Role;
    } & DefaultSession["user"];
  }

```

In callbacks we need to fetch the user from the database and add the `role` and `planId` to the session object. This is done to make sure that whenever you are working with Session from NextAuth.js you have all the necessary information about the user.

```ts theme={null}
  callbacks: {
    session: async ({ session, user }) => {
      const dbUser = await db.user.findUnique({
        where: {
          id: user.id,
        },
      });
      return {
        ...session,
        user: {
          ...session.user,
          id: user.id,
          planId: dbUser?.planId ?? null,
          role: dbUser?.role,
        },
      };
    },
  },
```

## External services

<Tip>This section mentions something about Emails</Tip>
<Tip>This section mentions something about Error Tracking</Tip>
<Tip>This section mentions something about Background jobs</Tip>

Next Auth is a great entrypoint for other services we need to use for our SaaS.

For example, here we use events to manage the following:

* Sentry - to connect user to the Sentry error tracking, so we could easily debug it.
* Trigger.dev - to trigger a background job to send a notification when a new user signs up
* Loops - to send a welcome email to the new users.

```ts theme={null}
  events: {
    async signIn({ user, isNewUser }) {
      Sentry.setUser({ id: user.id, name: user.name, email: user.email ?? "" });
      if (isNewUser) {
        if (isTriggerEnabled) {
          await slackNewUserNotification.invoke({
            user: {
              name: user.name ?? "unknown",
              email: user.email ?? undefined,
              id: user.id,
            },
          });
        }
        if (loops && user.email) {
          await loops.sendEvent(
            {
              email: user.email,
            },
            "cascade_sign_up",
            {
              ...(user.name && { name: user.name }),
              email: user.email,
            },
          );
        }
      }
    },
    signOut() {
      Sentry.setUser(null);
    },
  },
```

## Providers

Cascade comes with Discord & Google providers out of the box. You can easily add more providers by following the NextAuth.js documentation.

```ts theme={null}
providers: [
    DiscordProvider({
      clientId: env.DISCORD_CLIENT_ID!,
      clientSecret: env.DISCORD_CLIENT_SECRET!,
    }),
    GoogleProvider({
      clientId: env.GOOGLE_CLIENT_ID!,
      clientSecret: env.GOOGLE_CLIENT_SECRET!,
    }),

    /**
     * ...add more providers here.
     *
     * Most other providers require a bit more work than the Discord provider. For example, the
     * GitHub provider requires you to add the `refresh_token_expires_in` field to the Account
     * model. Refer to the NextAuth.js docs for the provider you want to use. Example:
     *
     * @see https://next-auth.js.org/providers/github
     */
  ],
```