Buy buttons

Buy buttons renders the quantity stepper and the add-to-cart button, plus the persistent sticky add-to-cart bar. Both buttons are real submit buttons of the same product form, so they share one cart state and both post the quantity the shopper chose. The button label switches to the sold-out text when the selected variant is unavailable. The low-stock line shows only when the variant tracks inventory, its policy is to stop selling when out of stock, and the remaining quantity is at or below the threshold you set.

Settings

Setting	Type	Default	What it does
Show “Add to stack”	checkbox	true	Controls show “add to stack”.
Stack builder link	url		Where “Add to stack” sends shoppers — e.g. your Stack Builder page.
Low stock threshold	range	10	Controls low stock threshold from 0 to 50.

Source

blocks/buy-buttons.liquid