A transfer never moves money across a border. The sender funds a pool in their country; the recipient is paid out of the pool in theirs. Pools run like warehouse stock, with a forecast, a reorder level and a lead time, and only the net imbalance between countries is ever wired. Simulation only. No real funds or banks.
Pools
Cash on hand On its way (wired, not landed) Stocking level S
What actually crossed a border
Paid out instantly
Balance against stocking level
Cash on handStocking level S