We just need to figure out the custodial part of cashu so that whoever mint the app chooses to custody the funds can't rug pull users.
Discussion
The client themselves is probably a good option for custodian.
I don't trust myself with that. I also don't have the legal structure to custody funds. :)
Smart move
What we need is some sort of auto-swap-out. And when a user reaches some artificial limit, the client warns them to get a lightning address to swap out to. This way the custodian only ever holds a small amount. But yeah, legal structure stuff, that's another challenge I don't even want to think about haha.