Nobody holds the hall yet. The sign over the door stays dark until $STAKEHALL goes live, and the first stake of 0.002 ETH lights it. Whoever tops that sends 0.003 or more and pays the 0.002 back to its owner as 0.0022, the extra 10% out of their own pocket. When the 20-minute clock runs out, the top stake gets its stake back plus the chest and keeps the hall.
0.002 opens the hall. Top it with 0.003+ and the 0.002 goes back as 0.0022.
A holds the hall at 0.02. B tops with 0.025 and sends 0.025 + 0.002 + 0.0005 = 0.0275.
A is credited 0.022: the 0.02 back plus 0.002.
Nobody tops B before the clock: B gets the 0.025 back plus the chest (0.0009 by then) and keeps the hall.
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