I'm sure you've seen this or similar paper before, but a good refresher from the windows 95 team: https://socket3.wordpress.com/2018/02/03/designing-windows-9...
Aside: Thank you for your video! It looks great and that's yet another OS I'd like to try and play with -- along with Plan 9, which Serenity made me think of a bit, and TempleOS because of the soul-saving effect of devoting to a hard piece of beautiful software craftmanship.