As someone who has worked with a lot of WMSes, I'd have to say that that is a domain that is extremely hard to get right. There is a lot of literature (as well

As someone who has worked with a lot of WMSes, I'd have to say that that is a domain that is extremely hard to get right. There is a lot of literature (as well as jokes) in CS about cache invalidation and how hard it is to get right. Well, inventory tracking and warehouse management are actually remarkably similar problems to cache invalidation problems, and you can get all of the same things wrong. But worse. Because unlike cache invalidation, inventory moves via unreliable human processes, has return logistics when you get things wrong (sometimes even when you get things right), and sometimes things just magically disappear.