@ColinTheShark Can you confirm this works without the need of an InputDialogPeer object?
If that works, it means the server accepts either types (as it happens in a bunch of other places) and thus I think we can accept the method having chat instead of dialog in its name for convenience.

Also, what about marking a chat as read instead? The raw method allows to do that too, but the issue here is the misleading name.

Can you confirm this works without the need of an InputDialogPeer object?

I haven't explicitly tested against an InputDialogPeer object but I can confirm that my snippet ^{(same raw method)} works both in private- and group chats.

Please also add a convenience method to user_and_chats/chat.py

You mean a bound method, right? If so, I added that already :)

Also, what about marking a chat as read instead?

While read_history can mark up to a specific point (or the latest message if no max_id is given), MarkDialogUnread just marks as unread. I have tried with unread=False as an argument, which didn't remove the unread status. I'm sure there is a raw method to mark a chat as read without using read_history, but I believe Clients just use the raw equivalent to read_history.