You mean something like Dropbox autosync? There is a drop_upload option in the tahoe.cfg file. I believe it works fine on GNU/Linux. Not sure about other OSes. You could always use 'tahoe backup' command.
Interesting, but not really what I'm talking about. On https://leastauthority.com/ there's mention of development of a "Magic Folder" tool that seems to do more of the sort of thing I'm looking at.
