Or do I need to use a route handler to be able to do this? I have a form I submit from a client component that is handled by a server action. The server action response sets a cookie on the client through cookies().set(...).

The issue is that Next.js v14 edge runtime (and v15 as well from what I've seen in the source code, not tested) currently [always encodes](https://github.com/vercel/next.js/issues/64346) the cookie value. Which the BE which parses this cookie later on cannot handle.

Using a route handler would allow me to manually put a Set-Cookie header on the response. But then I assume I lose out on hooks like useFormStatus() and useFormState(). So I'm curious to know if there is a trick to set headers on the response of a server action. I would like to avoid providing the cookie in the server action payload itself and having the client set the cookie. Since you lose out on the default security measures the browser uses to handle Set-Cookie headers.