How your basket works
Your basket is really several baskets at once — one per seller — that only come together at checkout.
One basket per seller
Adding a listing groups it with anything else from the same store. A different store's goods never share a line with each other; they sit in their own basket and become their own order once you check out.
A tap adds the minimum, not one unit
The first time you add a listing, the amount is its minimum order, not a single unit. If a listing has no minimum, that is one unit. From there you can step the amount up or down, or remove it entirely.
Stock is checked when you add, not just at checkout
Trying to add more than a seller has in stock is refused right away — you'll see a message that there isn't enough left, and nothing is added. This is checked again at checkout, since stock can change while items sit in your basket.
You cannot buy from yourself
If you are signed in as the seller who owns a listing, adding it to your own basket is blocked outright.
