What's the "ideal" way to debug proxy.ts? I have the file at the root of the app (same level as app), but as far as I've been able to determine it's doing literally nothing. I'm running Next 16.1.1 and the content of the file is as follows:

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function proxy(request: NextRequest) {
    const host = request.headers.get('host') ?? request.nextUrl.host;
    const domains = host.split('.');

    if (domains.length !== 3) return;

    const subdomain = domains[0];
    const rewriteTo = new URL(
        `/${subdomain}/${request.nextUrl.pathname}`.replaceAll('//', '/'),
        request.url,
    );

    new URL(request.url).searchParams
        .entries()
        .forEach(([key, value]) => rewriteTo.searchParams.set(key, value));

    return NextResponse.rewrite(rewriteTo);
}

export const config = {
    matcher: [
        // Exclude API routes, static files, image optimizations, and .png files
        "/((?!api|_next/static|_next/image|.*\\.png$).*)",
    ],
};