waxwing on Nostr: Definitely not my area but after a bit of reading it seems like this blog post does a ...

Definitely not my area but after a bit of reading it seems like this blog post does a really good job of explaining the pretty complex reasoning behind the double ratchet (used to be 'axolotl') setup:

https://signal.org/blog/advanced-ratcheting/

It seems like they're trying to address the difficulties of *asynchronous* messaging (users often offline for a while), as well as both forward and 'backwards' secrecy.