I could be wrong but i'm relatively sure that I reach message states that do not directly correspond to anything i typed into the editor -- which i wouldn't expect if the edited state was always sent in full rather than as a delta on a previous message state.

I suppose it's possible that the corruption happens on the client side tho --

1. initiate edit action and get editable view of snapshot of text

2. server acks some previous edit request causing some client state related to the message to update and promote a previous edit in some way

3. hit save after finishing editing -- and some delta operation on the client side updates a different message state than the one i initiated edit action from ...

This is just super unlikely as you describe it. There's no reason for deltas and fancy mechanisms when you can only edit your own messages. It would be a waste of resources to do it like this for short messages.

I don't know the specific implementation mechanism -- just guesses.

But that doesn't mean my observation of the behavior of the bug is unlikely.

And also -- there is not a hard requirement that only one editor exists -- the same user could use multiple devices at the same time. Consider that and you might find your assumptions to be invalid.