Say you want to build a simple app that only persists the user credentials and displays data from three separate calls. Would this make sense?: You have a GUI where you can enter the username and password. The GUI pushes this into an observable. There is a persistence thingy at the other end of the observable which persists it in a shared preference first and then pushes the credentials into a "verified credentials" observable (to make sure you don't use credentials that couldn't be persisted). This credentials observable is hooked into a retrofit request interceptor to do basic auth (because the server can't do anything better). When you want to display something in the GUI the GUI has an observable from one of the retrofit calls and pokes it to get a result which means the recent credentials will be used?