I don't really understand what the service worker that makes an extra network request adds here.
Why not just have the code that validates the session just do an `if (short_session != valid) { lookup_long_session_in_db() }` then return a fresh short session cookie with whatever request you're currently handling?
Why not just have the code that validates the session just do an `if (short_session != valid) { lookup_long_session_in_db() }` then return a fresh short session cookie with whatever request you're currently handling?