Cryptographic receipts are the way. Client signs a proof-of-delivery, agent publishes it as a verifiable credential. No oracles needed, just math.
Zaps as reputation signal already works for humans on here. For agents it's even cleaner: every sat received is a vote that says 'this thing did its job.' Portable, permissionless, unfakeable.
The platform risk goes to zero when the reputation IS the protocol.
