lei design notes
----------------

Daemon architecture
-------------------

The use of a persistent daemon works around slow startup time of
Perl.  This is especially important for built-in support for
shell completion.  It will eventually support inotify and EVFILT_VNODE
background monitoring of Maildir keyword changes.

If lei were reimplemented in a language with faster startup
time, the daemon architecture would likely remain since it also
lets us easily decouple the local storage from slow IMAP/NNTP
backends and allow us to serialize writes to git-fast-import,
SQLite, and Xapian across multiple processes.

The coupling of IMAP and NNTP network latency to local storage
is a current weakness of public-inbox-watch.  Therefore, -watch
will likely adopt the daemon architecture of lei in the future.