launchd there is
WatchPaths (and for some more specific case
QueueDirectories) which monitors changes on a path. However, if it is a directory, it will only recognize creations/deletions in the directory, i.e. not changed content of the containing files or any changes in any subdirectories (see here).
(For Linux, some good solutions seem to be listed here.)
It seems like
launchd is not able to do it, is it?
Or are there existing projects/tools which can do that?