Cannot set session strategy as JWT in NextAuth5

[synewmark]

Hi, I'm creating a project in NextAuth5 on Next15 and I'm running into a problem. I'm using Prisma DB connections for another part of the project, but I'd still like NextAuth5 to use JWT for Authentication. I have the following api\auth\[...nextauth]\route.ts file:

import NextAuth from "next-auth";
import CredentialsProvider from "next-auth/providers/credentials";
const { handlers } = NextAuth(
    {
        debug: true,
        session: { strategy: "jwt"},
        providers: [
            CredentialsProvider({
                type: "credentials",
                name: "Unverified",
                credentials: {
                    username: { label: "Username", type: "text" }
                },
                async authorize(credentials) {
                    const username = credentials.username as string;
                    if (!username) {
                        return null;
                    }
                    console.log("Authorized for user: ", username);
                    return {id: username};
                },
            }),
        ]
    
    }
);
export const { GET, POST } = handlers;

But when I hit POST api/auth/callback/credentials with the CSRF and Username I get back a authjs.session-token cookie not a JWT. What am I doing wrong? I can confirm my config is being picked up because the provider is working and I'm getting log outputs