I'd forgotten about that one... cosmo/ape (and *.zip) opens up a few interesting use cases for portability, but the in-place editing with web-dav and ability to use the browser as an IDE (file->save) would have to be built-out with something like redbean.

Seriously, if you haven't, go check out the "zen" of tiddlywiki: https://tiddlywiki.com/#GettingStarted

You download "blank.html", make changes, then save it as "mine.html" and you're off to the races. It's pretty wild!