At any point during this confirmation, should either player change anything in their basket (remove an item, add an item, change quanta, etc.) all activated confirmations will be deselected. For example, if I am Bartering an engine for 100 Quanta and I confirm this exchange, my partner may decide to change 100 Quanta to 50, which will automatically deselect my initial offer.
The exchange will proceed only when both parties have confirmed the exchange. Speaking in game terms, if I am Bartering an engine for 100 Quanta and confirm this exchange, and neither basket is modified, once my partner activates their confirmation, the trade will instantly complete.