post compromise recovery requires key rotation and really should have a context of a connection

the point about the stable identity is part of the problem, to do post compromise with nostr you have to add a new form of temporary identity called a conversation... the identity is revealed to participants in the process but it is not the identitity that is maintained during it

so, yeah, it depends a lot on client state and that's why all the signals and whatsapps and sessions and suchlike are in a shambles, and i don't think MLS fully solves the problem, it does provide a mechanism for maintaining per-discussion identity but it doesn't deal with the "and then" part of it