I'm actually fine with the wire approach.

But it would be nice if the sender could be notified that the message was never delivered.

Each Wire message has a user-visible status: Failed, Sent or Delivered.

It's not obvious, but if status never changes from "Sent", then it wasn't "Delivered".

There's a new icon now as well with an "eyeball" that tells you if the message was viewed. The option for this read receipt can be enabled in the options if both parties enable it.

Matrix does have end-to-end encrypted persistent history.

Yes, it's possible. Depending on your threat model, it may or may not be a good idea to have a long-term archive of encrypted data be subject to legal process. Matrix has plans to support IETF MLS, which is a necessary precursor to messenger interoperability.

Matrix lets you configure the history retention on a per-server or per-room basis, fwiw: https://github.com/matrix-org/synapse/blob/develop/docs/mess.... From a metadata perspective, we're working on P2P to avoid metadata accumulating on servers. In terms of the OP here (address-book based contact discovery), https://github.com/matrix-org/matrix-doc/blob/hs/hash-identi... is how Matrix optionally implements it while trying to preserve privacy.

Yeah, I guess it’s just a different use case, but it was a behavior I didn’t expect (maybe I didn’t read the “fine print”) and it turned me off using it for long-term stuff. It’s a pity because I liked the interface and features.