auth member should be compatible with NextMiddleware

[cefn]

Goals

1. A prominent documented example implies that the auth member returned by NextAuth has compatible signature with NextMiddleware
2. This seems to exploit lack of adequate typing in NextJS paradigm
3. Actually attempting to use auth in a type-safe way reveals it has no compatible signature

The example code below is offered right on the frontpage as documentation for Auth.js but seems not to be type-safe. It exploits the fact that NextJS is poorly typed through automatic loading of named files with conventional exports having no typing.

This is concerning because it does not ensure that the code paths in auth can actually process the arguments passed from middleware, and even if they handle them by good luck now, this is not being guaranteed by typescript for the future.

At the time of writing the frontpage shows this...

// auth.ts
import NextAuth from "next-auth"
import GitHub from "next-auth/providers/github"
export const { auth, handlers } = NextAuth({ providers: [GitHub] })

// middleware.ts
export { auth as middleware } from "@/auth"

// app/api/auth/[...nextauth]/route.ts
import { handlers } from "@/auth"
export const { GET, POST } = handlers

If you transform the middleware implementation to its type-safe equivalent, the code no longer compiles, because the auth member returned by NextAuth doesn't have a compatible signature with NextMiddleware ...

import { auth } from "@/auth"
import type { NextMiddleware } from "next/server"

export const middleware: NextMiddleware = async (...params) => {
    await auth(...params)
}

The error reported against the invocation of auth(...params) is...

Argument of type 'NextRequest' is not assignable to parameter of type 'NextApiRequest'.
  Type 'NextRequest' is missing the following properties from type 'NextApiRequest': query, env, aborted, httpVersion, and 67 more.ts(2345)

This makes me concerned that the auth signature cannot be reliably used without error in app routes, only API routes. Is that true?

For context below you can see the interactive screenshot from my own codebase ( note: in my codebase the auth.ts file is under /lib ).

Non-Goals

1. I am not proposing a change to behaviour, only to typings for code quality, developer experience and future type-safety.

Background

NextMiddleware is presented as the correct typing for NextJS middleware

Proposal

An overload for the auth member should be added, aligned with NextMiddleware