You could try the Nimbalyst app. It features a visual Kanban board for parallel sessions, visual editors, and it is also an iOS companion app. This is my sugges

You could try the Nimbalyst app. It features a visual Kanban board for parallel sessions, visual editors, and it is also an iOS companion app. This is my suggestion if you are looking for a straightforward GUI focused on single-session chats. I don't know if it offers the full features you are looking for, but you could always do a search on it to be sure.