One more, on the next order

The add-on card on a subscriber's portal page, and the billing reminder email before it, now open with a stock-up offer: one more unit of the product they're already subscribed to, added to their very next order only, at the same price their subscription already charges.

This is different from any other add-on recommendation shown on the same card: it isn't a new product to try, and it doesn't change the ongoing subscription. It's a single top-up for the next order only, priced at whatever the subscriber's existing line already pays, so there's no new discount to work out and no surprise at checkout. The row shows a struck-through base price next to the subscription price and the percentage saved, exactly as the rest of the subscription already shows it.

Clicking "Add one" updates the next order's total right away, and the row then reads "Added" so the subscriber can see it went through without reloading the page. A subscriber who opens their portal from the reminder email gets the same offer, already tracked as having come from that email.

The stock-up row sits above any other add-on recommendation on the card and in the reminder email, and respects the same on/off switches merchants already use for the add-on carousel and the reminder email's add-on block. Those switches previously only worked for merchants on certain plans; they now work on every plan, so any merchant can turn the carousel or the reminder email's add-on block off entirely if they'd rather not show it.