use ETags and browser cache to create memoized remote functions

Describe the problem

Because remote functions can't set headers I can't use ETag and the browser cache even when I'm certain the remote functions return value hasn't changed

Describe the proposed solution

offer a new type of remote function along with query, form, command and prerender

import { memo } from "$app/server"

export const getData = memo(async () => {
  const { etag } = getRequestEvent();

  if (dataStillFresh(etag)) {
    return // returns 304 Not Modified
  } else {
    let [etag, data] = getFreshDataAndToken()
    return [etag, data] // sets the ETag header
  }
})

Alternatives considered

The current alternative is to use load functions, which allow setting of the response headers.

Another alternative is to allow setting of response headers from remote functions.

Importance

would make my life easier

Additional Information

No response

Start with the remote functions entry point in $app/server and compare it with load functions, which the issue identifies as the current way to set response headers. Determine the scope of a memo remote function or header-setting alternative, including the requested ETag and 304 behavior; done should be defined by the chosen design and its browser-cache behavior.