All known users go into a .user/all directory, named by their hostmasks.
Any users that are online, are symlinked to .user/online, named by their
nick.
A user that parts the room is them symlinked to .user/offline.
These symlinks are cleaned up whenever the daemon is restarted.
Right about now I've completely ditched the whole
'chatd-JSON-standard-chat-format' thing. A much
cooler idea has struck me:
Chatdir! It's Maildir, but for chats! Must I
really say more?