7f37b37be3
Q2 measured, not guessed. The operator moved a card Club -> Transfer List without listing it (PUT /item, no POST /auctionhouse) and the state was captured read-only. Finding: we do not represent the unlisted state on the wire AT ALL. Such an item is byte-identical to a club item -- itemState `free`, no `pile` field emitted, still returned in /club and counted in clubPlayers -- while an actively-listed item is correctly excluded from /club and present in tradePile. Only the host's own pile store knows the difference. Trade pile held 6 items: 1 listed, 5 unlisted. The FIFA 17 ENCODING of that state stays UNKNOWN on purpose: returned itemData.pile is numeric with an unrecovered mapping, and tradeState is a closed table walk where an unrecognised bidState is silently swallowed as `none`, so a wrong enum produces a plausible-looking but wrong UI. The corpus warns `inactive` decodes but no client path treats it specially. One client-only discriminator is recorded instead. Also models the domain boundary both limbo bugs came from: pile membership and auction lifecycle are separate facts requiring coordinated transitions. States the testable invariant -- an item must never be simultaneously excluded from /club and absent from /tradePile -- with the two ways it was reachable and the commits that closed each.