Detecting Cycles in the App

Previously we just basically always stored the ID of the board where the user was last on. Now we actually have to store the entire navigation stack including every card. This all gets serialized to disk when the app quits so that when you launch the app again we can look at these breadcrumbs and retrace the steps to exactly where the user had come from. We're going to have to do that probably with all kinds of things like deep links or like sharing URLs for go to the sports well. Do you remember anything about detecting cycles like sort of putting a linked card inside itself?