The request
“Enable pre-order. Swap the buy button for a pre-order button only when a variant is out of stock. Variants with inventory should still show add to cart.”
The brand sold both in-stock and made-to-order versions of the same product. The button needed to reflect which one the customer had selected.
The approach
We made the buy button variant-aware. Out-of-stock variants show a pre-order button with an estimated ship window; in-stock variants show add to cart. Pre-orders are tagged on the order for fulfillment.
What we shipped
Variant-aware pre-order button
Estimated ship window shown on pre-orders
In-stock variants unaffected
Pre-orders tagged for fulfillment