Imagine a comms #UX, where I could choose a contact, choose a rough message length (say, short, medium, or long), and the software would give me an appropriate compose UI for that length of message, and poll the receiver's comms app to determine what protocol they prefer to receive each length of message on. Eg. I could set my app to tell senders I want to receive short messages by SMS, medium ones by #ActivityPub, and long ones by email.