How do promotions and discount codes work across stores?

Percent off, dollar off, buy one get one. Per store, per group. A promotion engine on every store: percentages, fixed amounts, buy one get one, shipping deals, minimums, date windows, codes. Point it at a whole store or at one customer group. The margin floor holds underneath, so a location can't promo itself under cost. Every promotion's sales show as their own line in the cockpit, so you know which one actually moved product. Stack them where you want to, block stacking where you don't, and set a per-customer limit so the code doesn't leak to the whole roster.

What it used to cost you: A code someone forgot to turn off in February, and the margin it took with it.

The feature is called Promotions. It runs on the same rails as everything else here: one catalog, one price list, one cockpit, your name on the front.