so the wallet event specifies that wallet's relays

token events are stored on those relays

nut zaps are published on relays following the outbox model, since it's a message from sender to receiver

so imagine this:

you create Wallet A, you designate that wallets relays to be wss://umbrel.local -- only you have access to read/write on that relay

I send you a nut zap -- I check your outbox relays, which are some publcly accessible relays

I publish the nut zap there, pubkey-locked, unencrypted

once you swap it, you encrypt the new token and save it on wss://umbrel.local