I've been using https://www.irccloud.com for years, it takes care of all these things and also has an app / push notifications. It's still IRC, but it takes care of a lot of the annoying parts of it that made it feel dated.

If you make IRC centralised like this, you’re taking everything away that makes it IRC. You could build the same thing with XMPP, Matrix, or Signal.

It's as centralized as everyone running their znc on Hetzner. It's mostly just a bouncer with a nice web interface (Like The Lounge) and a rudimentary app for people who want to pay someone to run this setup. You'd still connect to Libera and other networks and there's zero lock in.

I never worry about presence in any form of chat. I don't care if people are there when I message them; it's up to them to pick up my messages at their convenience.

Which is never if the person you messaged did not have a bouncer or their bouncer crashed.

Crashed client / bouncer should mean it's still in their local log. Bots can also deliver messages pretty commonly. Usually it's `.tell nick message` and next time that nick connects and posts they'll see it.

Presence is the defining feature of chat. Without it, you're using a forum.

The difference between a forum and a chat is mostly UI and structure.

On a forum, every conversation is within a thread for example.

Chat is unthreaded by default, even if Slack allows threads. It also allows users to create channels and manage who's on those groups, while the forum equivalent is fixed up-front and only opt-in.

So really chat is a forum that's a bit more free-form.

The Lounge https://thelounge.chat/