Vitalik-inspired AI payment system can send expired deposits to its treasury

The Ethereum Foundation's Oct. 1 announcement that zkAPI is running on mainnet gives the private AI-payment design coauthored by Davide Crapis and Vitalik Buterin a concrete financial-control test: how does a user get unspent money back when the billing server stops cooperating?zkAPI, a billing system for metered APIs, documents an onchain withdrawal route that does not require the server's clearance. But a user's ability to recover a balance depends on which spending state they hold and whether they can start an exit in time. The implementation's pause powers and expiring notes put boundaries around that control.Open Anonymity built the implementation with the Ethereum Foundation. Crapis and Buterin published the underlying design on Feb. 11; the foundation's October announcement credits the team that turned it into software and contracts. Etherscan records the announcement-linked vault's creation on Sept. 30, a day before the announcement.The announcement describes its linked vault as holding USDC credits. The current mainnet manifest identifies that same vault as native ETH, with balances accounted for in whole gwei. Its explorer activity also shows ETH-valued deposits and close...