so its explicitly designed to be doublespend + rugpull tech. makes sense. I guess that is technically a feature for the sender
Imagine you give your waiter a tip or gift someone else some sats via cashu as a present. If you see then after xyz time that they still have not redeedem your gift you can just take them back instead they getting lost/unused. Obviously as soons as they are accepted/reedem you can't get them back.
So I guess what nostr:npub1g53mukxnjkcmr94fhryzkqutdz2ukq4ks0gvy5af25rgmwsl4ngq43drvk was saying is e.g. I could send you know now 100k sats in cashu via DM and say please build xyz into damus. And if you don't want or ignore my request I could always get my sats back without having to ask for a refund.
Discussion
None of this is great for adoption.
No, once you accept the payment it's yours. No way to get it back. But in the end thats not the main use cases for ecash. More about scalabiltiy and privacy imo.