Product inventory cap: limit a product to a fixed number of total sales

Request

A way to set a total inventory on a product, so it can only be sold a fixed number of times across all buyers, after which checkout stops accepting it. The common case is a one-of-one item sold first come, first served.

This is distinct from quantity on an order, which limits units per purchase rather than total sales.

Current behaviour

There is no inventory, stock or sales-cap field on a product, in the dashboard or the API. Discounts have usage_limit, but that caps redemptions of a discount code, not sales of a product.

The only workaround is to listen for payment.succeeded and archive the product with DELETE /products/{id}. That is not atomic: two buyers checking out at the same moment can both complete before the archive lands, which is exactly the case that matters for a single-item sale.

Asked for

A total_inventory or equivalent on the product, enforced at checkout, with the product shown as sold out once the count is reached.