watch a simple dir

[Konstantin Ryabitsev <konstantin@linuxfoundation.org>]

Hello:

I'm playing around with using public-inbox as the archiving subsystem for
mlmmj. I know it's possible to simply configure a local address to deliver to
public-inbox-mda [1], but I wonder if there's a way to reduce complexity and
simply configure public-inbox-watch to monitor mlmmj's "archive" directory for
any new files, similar to how it would monitor a maildir:

- it's a simple flat dir of numeric files corresponding to the number of the
  message in the index
- each message is a valid rfc2822 document -- in fact, if I copy them into the
  "new" folder of any maildir, I can read them with mutt
- however, if I use symlink trickery to make mlmmj deliver into "new" or "cur"
  of a maildir monitored by public-inbox-watch, they are ignored -- so things
  are not as easy as that. :) Probably, it expects to have more complex
  filenames instead of just a number, but I didn't dig too deep.

So, any way to make this work either by tricking public-inbox-watch to
recognize these as valid maildir entries, or by teaching it to monitor simple
additions to a dir as parallel scheme to maildir:?

-K

[1] adding an extra hop to deliver to public-inbox-mda, or to a maildir
monitored by public-inbox-watch adds another entry into the postfix queue,
bloats the headers by adding more Received: lines and generally seems like an
inefficient way to basically copy a file that already exists on the filesystem