Comment by jubilanti

> What mechanism is it that you think exists that would sound the red alert when the last library (or even the second to last) is about to get rid of the very last copy?

Doesn't need much coordination. Before getting rid of a book, search for it in that shared catalog you allegedly have your nose in constantly. If you're the last or second to last copy, then you know. Unless two libraries are independently doing this at the exact same time.