Feature request: create backup

[kookma]

I use webdav with Tiddlywiki

https://tiddlywiki.com

It is a single file self contain html one can edit it over the http. When you save a modified file webdav save it correctly! I wish to be able to create a backup file when I save the file.

In other words

Having test.html open and modify using webdav! how can I make a backup on every save?