One decision here which seems like a large break from the original pi is that Durable doesn't support branching conversation trees, it only supports conversation forks with ancestry information. Can anyone speculate (or confirm, if you happen to be Armin or Mario) why this is, and if that is necessary for the durable guarantees? The branching conversations are still an immutable data structure, so I can't see why this would be necessary, but perhaps I'm missing something.