Of course, we can work together to refine the Double Ratchet Algorithm used in message encryption.

Keychat not only incorporates the Double Ratchet Algorithm used for message encryption but also includes metadata privacy and ecash as stamps. Therefore, we might need an NIP that describes all aspects of Keychat’s design.

Furthermore, Keychat is an application focused on chatting, not just DMs. DM implies that it's merely an ancillary feature of a Twitter-like application.