The relationship between NIP-4 and NIP-17 is similar to:
iPhone ↔ iPhone: It uses iMessage first (Apple’s service). Blue bubbles.
iPhone ↔ Android: It uses SMS/MMS (the carrier’s traditional texting standard). This isn’t an “Android-only protocol,” it’s the old common language that all phones can speak. Green bubbles.
If at least one person in the chat is using a client that supports both NIP-4 and NIP-17, interoperability is no longer an issue.
In practical terms, could it be possible for a Keychat user to send a message to a Damus or Primal user, but it’s just a link to download the app, similar to the one-time link but without the metadata?
Right now, if you log in to Keychat with your microblog ID and someone sends you a NIP-17 DM, Keychat can directly reply using NIP-17. We haven’t really talked about this feature much, so you might not be aware of it.
It can also receive NIP-04 DMs, but Keychat doesn’t yet support replying using NIP-04. We’re still debating whether we should support NIP-04 replies.
