Stock, and why you cannot oversell

This lesson prepares you to: Set stock correctly, choose whether to track it, and explain how Helm prevents two buyers taking the last item.

The default is zero

A new product starts with 0 in stock and stock tracking on. That combination means the listing is live and unbuyable. It is the single most common reason a new seller sees traffic and no orders.

Set a real number, or turn tracking off.

Turning tracking off

If you make to order, sell a digital item, or simply do not want to keep a count, switch stock tracking off. Helm then stops checking availability at checkout entirely and your listing can be bought any number of times.

That is the right setting for a lot of small sellers and the wrong one for anybody selling a limited run. Choose deliberately rather than by accident.

Two buyers, one item

This is the failure that ruins live selling on other platforms: the same last item sold twice because two people tapped buy in the same second.

It cannot happen here. Stock is taken with a single guarded database write that only succeeds if there is enough left, rather than by reading the number, thinking about it, and writing it back. The second buyer's write matches nothing and their checkout is refused. The migration that introduced it names this outright as the number one live shopping consistency failure, which is why it was designed in rather than patched later.

Stock is decremented atomically at checkout. There is no window in which two orders can both win.

When stock comes back

Stock is returned to you automatically in the cases where an order never completes:

• The buyer's checkout session expires without payment.
• The payment page could not be created at all.
• A parent denies a minor's purchase.

Variants hold their own stock

If a product has variants, each variant carries its own count and Helm takes stock from the variant rather than the product. Set them per variant or the numbers will not mean what you think.