Queuing in a filesystem? The proper locking is also a little confusing, at least if you want to do it cross platform. Filesystem events? I have no idea how that works; in theory there are ways of efficiently detecting changes to files, but there's no unified cross-platform way to do it (and even single platforms have multiple ways to do it). Sure, the filesystem could (maybe) provide infrastructure for these things, but we would still need better tools.