The token is locked to the receiver (P2PK) and the receiver can validate the mint's signature without communicating with the mint (DLEQ) – both of these properties together make the transaction final 😉
Discussion
There's something really special about this project. It's very addictive and pleasing to see these developments happening as ongoing threads
How to make an ecash transaction that is final without needing a roundtrip to the mint to prevent double-spending.