So that tool would allow me to store events to disk but also to load from disk and could show me side-by-side a list of replaceable events to dig into. In a first iteration it wouldn't need to know about all the details like contact lists but if I lost my contact list and there was a tool that would tell me that this event went from 200 tags to one, I would revert it and see what happens. Right now it would be very annoying to lose all my follows to some bug.