Accessing User-Agent from Next.js Route Handler?

I'm trying to access a request's User-Agent header from a route handler I have on my next.js project. Here is an example:

import { userAgent } from "next/server";
export const dynamic = "force-static";
export async function GET(req: Request) {
  console.log(userAgent(req))
  return Response.json({ error: false, message: "Hello, world!" });
}

The console.log function returns this:

{
  ua: '',
  browser: { name: undefined, version: undefined, major: undefined },
  engine: { name: undefined, version: undefined },
  os: { name: undefined, version: undefined },
  device: { vendor: undefined, model: undefined, type: undefined },
  cpu: { architecture: undefined },
  isBot: false
}

The above code is using the userAgent function, which I know is designed for middleware, but for some reason middleware doesn't seem to have an effect on Route Handlers. I've also tried:

1. the headers function
2. Using req.headers.get("User-Agent")

and all of the approaches return a null/empty string value. I know the request doesn't send a null user-agent because if I send a request to the same hosted project on Vercel and open up the Logs, the request shows a valid User-Agent column.

The issue is because you specify: export const dynamic = "force-static";

You’re telling Next.js to generate the route at build time. Static routes are pre-rendered and do not have access to the req object at runtime because they are generated without a request context.

Also, in route handlers (like your GET function), you receive a standard Request object, and userAgent may not work as expected.

Remove/comment out force-static and your agent data should appear in req.headers.get("user-agent")