On the Friday of a November promotion we sold three hundred and forty cordless drills on a marketplace that we did not have. The listing had said fourteen in stock for most of the afternoon. Our warehouse system had said zero since a quarter past one. Two of our integrations write to that marketplace's listings API. The stock job runs every five minutes: it fetches each changed listing, sets the quantity, and sends the listing back with PUT. The price job does the same with the price. PUT rep...