Yeah, I'm still have trouble with drawing a line around Dartg's side of the trade and acting like we don't have to account for the change in demand that occurred when his counterparty created his ask.

Either we must account for all possible demand levels at all times or we only may account for them at the time they are realized in a trade. We can't choose to account for changes in demand at one time and not another because both levels of demand are expressed in the same trade.

I disagree here. My read is that Darth's trading partner also had to be more willing to part with something than he previously was.

This is more or less where we were about ten iterations above. I will spend more time thinking about your answer there (#876535) and see if I cannot better explain my disagreement.