[BUG] Matched bids can be withdrawn.

[Racoda]

This happened to me when trying to drop Holland DS6 in this auction: https://www.nationstates.net/page=deck/card=63/season=2
Holland D6 was the first to (accidentally) trigger the bug, but I then successfully reproduced it. I suspect it's a race condition, possibly due to removing bids not requiring a security check and same value bids not being differentiated.
Generic example:

Suppose the auction looks like this:

Seller	Ask	Match	Bid	Buyer
			1.00	Alice
Alice	1.00	1.00	1.00	Bob

Bob places another bid at 1.00:

Seller	Ask	Match	Bid	Buyer
			1.00	Bob
			1.00	Alice
Alice	1.00	1.00	1.00	Bob

So far, everything seems normal. Notice that both Bob's and Alice unmatched bids are equal to the matched one but have been placed later (this is important). Both Bob and Alice can withdraw their unmatched 1.00 bids.
However, Bob can use this bug to also withdraw his matched bid. To do so, he must open two tabs and withdraw the unmatched 1.00 bid in both tabs in quick succession/simultaneously. NS will then withdraw both the unmatched ask and the matched one, leaving Alice matched with herself:

Seller	Ask	Match	Bid	Buyer
Alice	1.00	1.00	1.00	Alice

Sidenote: A probably related (but non-game-breaking) bug is that an ask cannot be removed if it is equal to one that's already matched:

[Holland DS6]

I think I encountered this bug a few days before, though it was a visual glitch, and was shocked to find I could sell it and buy it like in the current auction. As I talked with Racoda with it, I actually managed to find a way to recreate the bug and infinite amount of times with only one NS tab open though. In my testing right now with my puppet with another card, and lets say that all 2 or 3 asks my puppet has the top 3 bids so it matches like in auction, and if I bid the same amount as the other bids, then very quickly remove that bid, it actually removes my puppet's bid entirely and I am now the 3rd bid (like trying to buy the cheap ask like with the example legendary Rocoda said)
To make it a little more visual, here is a recreation of the bug like Racoda from my own testing, starting with a classic example of someone accidentally asks for 1 bank instead of an example market value of 15, for say (Made up scenario, but based on my testing)(Don't really know tables)

Example player with ask at 1 bank:
Player/nation B, normal ask at market value of 15:

Asks: Bids:
15 (My actual nation quickly puts up a bid of 15
Nation 1: 1 (Matched at 8.) 15 My puppet (for reference)
Nation 2: 15 (Matched at 15) 15 My puppet (again, for reference)

After I bid 15, not matched in the auction, and then I quickly remove the bid turns into this:

Asks: Bids:
1 -------------- 15 (Now from my nation, the bug is now I am matched when shouldn't be)
15 -------------- 15 Still my puppet paying the full 15 and not the 15 and 8 for the ask of 1 being matched at 8 (15+1/2)

Edit: I think it only works when there are at least 2 auction matches and not just one, but this needs a little more testing

[Holland DS6]

I thought it was patched, but still noticing it again, especially in the bidding war I am in now with this card: https://www.nationstates.net/page=deck/ ... 4/season=2

The bug seems that it mainly just switches around the order of the bids as long as they are all the same amount bid

[Racoda]

Bump

Also, did some more testing. Removing both bids at the same time isn't actually necessary. You only need to remove the bid that appears "lower", but the one higher will be removed.

My understanding of the problem, from what I've observed, is the following:
The server removes equal value bids top-to-bottom (ie. first equal-value bid placed is the first to be removed). This succeeds despite the bid being matched! Presumably, the server checks if there is *any* bid of that value that can be removed, and removes the first placed one.

The same happens with asks — the server tries (and fails) to remove asks bottom-to-top (ie. first equal-value ask placed is the first to be removed). This fails because it is matched.

If what I've described is correct, the fix is pretty simple: remove equal-value asks/bids in reverse order, like a stack: last placed is the first to be removed.

[Holland DS6]

Bump, are the mods aware of this bug to call it one, since it may be able to be reproduced infinity as long as the person has a matched and non-matched bid, like in this card, which ironically its for gifting Fris's card to me
The epic which it shows this 'bug': https://www.nationstates.net/page=deck/ ... 4/season=2

[Frisbeeteria]

are the mods aware of this bug

We've known about it for over a year. We just can't seem to find and fix the root cause of it.

which ironically its for gifting Fris's card to me

Thanks so much for using me as your test case.

[Ioavollr]

...
Sidenote: A probably related (but non-game-breaking) bug is that an ask cannot be removed if it is equal to one that's already matched:

(Image)

I experienced this one today, and at Giovanniland's suggestion cancelled the unmatched ask, which worked.

[[violet]]

are the mods aware of this bug

We've known about it for over a year. We just can't seem to find and fix the root cause of it.

I didn't know about this one. I'll look into it.

[[violet]]

So this is kind of fixed now.

When withdrawing a bid (or ask), and you have more than one at the same price, the server will now default to removing the newer one rather than the older one.

This is not quite the same thing as removing the exact bid/ask you meant, as you can tell if you happen to have two identically-priced bids separated by another person's also identically-priced bid. That will require a little more work.

Also this may be hard to perceive, because on the site it's hard to tell the difference between removing one identically priced bid or another.

This is not related to the issue of bids being sorted from "least preferred" to "most preferred" by ascending price + descending time, which is a design decision, and can allow newer (less preferred) bids to form more favourable matches with lower-priced asks.