ecash works a little differently. It’s basically just a custodial LN balance. The way to think about it is: you’ve got some sats with a mint. You can either spend them like normal over lightning, or you can turn some sats into ecash. When you do so those sats are instantly pulled from your balance, and you get an ecash token you can share through text, SMS, NFC, whatever.
To keep things simple I think the balance should always just be shown in sats. That’s what I’m pushing for.