The amount closes the whole position (withdraw: pays the floor balance; repay: burns every debt share and refunds excess).
Hub utilization (0..1) after the action at amountBase; null when not applicable.
Which gate produced amountBase; null when only the position size bounds it.
Token base units. For a full-close withdraw this is the floor payout; sign
"0"(the builder's withdraw-all sentinel) instead.