Correctly order late-arriving activities
While chatting with the mastodon crowd and talking about our thread fetching system nightpool mentioned the following case:
what happens when someone sends you a private post that replies to another private post, and then sends the replied to post much later? because of e.g. queuing delays or whatever.
It's true that this case is currently not handled correctly, because it will lead to a post having a higher id than it's reply and will thus cause them to be ordered wrongly.
This is a rare case, but it would be nice to handle this by assigning an earlier ID to the post that arrived too late.