New Kitten Release 
• Implements cascading archives support
https://kitten.small-web.org/reference/#cascading-archives
Cascading archives¹ is useful if you have a static archive of the old version of your site and you don’t want to host it somewhere else and use the 404→307 (evergreen web) technique (https://kitten.small-web.org/reference/#evergreen-web-404-307) (the latter is useful if the old version of your site is a dynamic site and you cannot take a static archive of it).
If a URL cannot be found on your app, Kitten will trying it in the archive folders:
__archive__1
__archive__2
__archive__3
(In that order.)
So you can three older static versions of your site served without breaking older URLs unless they are shadowed by newer URLs in your site/app.
Enjoy!


¹ This is a feature that I originally implemented in Site.js (that’s going to be shut down tomorrow when Let’s Encrypt stops issuing certificates with OCSP-stapling – I don’t have the bandwidth to maintain two servers/frameworks; Kitten is Site.js’s successor). I’m planning on implementing this differently in Kitten going forward (so you can use the Settings interface to upload a zipped archive and it will serve it) but I need this for my own site for tomorrow’s shutdown so we have this simpler implementation in the meanwhile. Leaving things to the last minute? Who? Me? Never! ;)