I'm probably clueless and shouldn't talk, but won't the renaming of bogus.zip to target.zip also wake up your watchdog? Seems like it should, at least..
Well it would, if I was monitoring that directory. The point is the creation of the ZIP would trigger it as well. And I am afraid the service would be waked even every time the FTP server writes another chunk of data into the file. And THAT is what I do not like. It's not a big problem, but I do not like it.