Seat race: conditional append decides

Two racers, one conditional append, one winner; expiry and correction ride the same log (teaching numbers)

Seat race: conditional append decides Two racers, one conditional append, one winner; expiry and correction ride the same log (teaching numbers) HoldSeat A5 @v3 HoldSeat A5 @v3 append iff seat v==3 conditional append: version decides appended v4, u1 wins held (u1) SeatTaken, try another confirm A5 append SeatConfirmed on SeatConfirmed ticket, key e-77 resend ticket e-77 resend blocked, exactly once sweeper: HoldExpired B2 10-minute hold TTL cancel B2 booking append BookingCanceled fresh event, never an edit Race Confirm + send once Expiry + cancel Viewer A · first racer · Sequence participant Viewer A first racer Viewer B · second racer · Sequence participant Viewer B second racer Booking API · conditional writer · Sequence participant Booking API conditional writer Event log · append-only, ordered · Sequence participant Event log append-only, ordered Ticket sender · idempotent key · Sequence participant Ticket sender idempotent key Legend main request return async trace message