I’m not sure if I like the change of the Map key type to Object (I’d probably go with two separate maps instead), but I don’t see how it might be harmful either.
It may be a good idea to make the sending behavior configurable (i.e. disable sending updates for group chats only).
If you don’t mind I’d create a PR in your name for more comfortable code review.
Edit: I created #352 with your changes.