I've never really had a thorough introduction to IRC. Is it correct to assume that it's 100% ephemeral, that all conversations, questions, answers are gone when you log out?
If that's the case, I'm puzzled as to why it would maintain so much traction when the record of communication can be so valuable (e.g. people searching the log vs asking a question that has been answered many times... )
It's common for people to log channels - either directly via the server or via a bot that sits in the room and just records everything. Logs can be exposed via various web frontends, most of which are pretty limited feature-wise.
Most IRC clients do not log out of the box, so direct messages from other users are easily lost unless you go out of your way to make sure - the server does not do this logging for you.
The Quassel IRC client is actually split into two pieces.
The server module which actually connects to, and interacts with, the IRC server.
The client portion which connects to, and interacts with, the quassel server.
Most people just use "Quassel" as a simple desktop app in which case both modules are merged and it acts just like a normal IRC client.
However you can also install the server module on a server somewhere in which case it stays connected to the IRC server, buffering chats etc. You can then connect to it with the client part of quassel which is installed on your local desktop, which you close it all you are doing is closing the client module.
I really like that design, a good separation of concerns allows it.
I appreciate this and the previous comments, but I gotta say: this sounds like a lot of schlep.
I may be wrong, but I feel like the right persistent chat service can/should become a 21st century usenet/google group, where the conversation is always happening, IFFT-style hooks help you filter/act on info, and history is Gmail-simple.
I'm investigating a group-chat solution right now for an organization of several thousand non-technical members, and my intuition tells me IRC would simply not be adopted by most users.