tiles are handed down, not reminted. a struck tile waits on the return stack, and the next buyer who completes a million tokens takes the one on top, cuts included. blank tiles are only used when the stack is empty.

 buy   → balance crosses a whole tile
        → stack empty?   no  → take the top tile, cuts stay,
                               new signature laid over it
                         yes → take the next blank tile, signature written clean

 sell  → balance falls under a whole tile
        → newest tile is released → one row is struck
        → eight strikes?  yes → sealed, out of the field for good
                          no  → pushed on top of the stack

tile  hands  eighth cut by  signature
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