Treat each payout like a glacier: it creeps forward and stays frozen through a week-long challenge window. In that window any seat can post a bond and dispute a payout by showing the work copies another seat's output or was never really checked. A winning challenger takes the frozen reward; a losing one forfeits its bond. The anchor is that only payouts surviving scrutiny ever thaw, and every frozen claim is a public lantern inviting rivals to hunt sybil farms for profit.