tiros, thanks for putting this together. I do agree that refund requests and completion should be tracked in the OP.

However, I don't think that FIFO is the fair way to do it. Seems like it's letting Yifu off easy--which appears to be what's he's trying to make happen.

Suppose you had two spots in Avalon's queue (among many other buyers), and Yifu says, "sorry we're delayed, you'll have to give up your first spot (refund), but keep your second," (EDIT: which is behind many other buyers) would you really think that was fair? The buying should remain FIFO (first-come, first served); thus the refunds should be LIFO. This also shows the full extent of the delay, which I think is appropriate.