Transaction flow — happy path vs. exception path

Settlement

The moment value actually changes hands and the deal is genuinely done — not just agreed, promised, or sitting as pending. Before settlement, someone is still owed something.

For example: You tap your card at 9am and the shop says 'approved'. That is authorisation, not settlement. The money may only actually leave your account two days later — that later moment is settlement.

Sanctions screening

Checking every payment's sender, receiver and purpose against government lists of banned people, companies and countries before the money moves.

For example: A payment to 'M. Ivanov' is automatically held because that name resembles someone on a sanctions list. A human then checks whether it is the same person or an innocent match — most are innocent, which is why the review step exists.

Exception handling

What the product does when something goes wrong — a failed check, a timeout, a duplicate request. Who is told, who owns fixing it, and what the customer sees meanwhile.

For example: A transfer is held by a sanctions alert. Good handling: the client immediately sees 'under review, reference 12345', a named team owns it, and there is a deadline. Bad handling: the payment silently disappears and the client phones to ask where the money went.

Reconciliation

Checking that two separate records of the same thing actually agree — for example that the token ledger and the bank's main account system show the same balance. A mismatch is called a break.

For example: Like comparing your receipts against your bank statement at month end. If the statement says HK$4,000 and your receipts total HK$4,200, you have a break and must find the missing HK$200 before closing the books.

Atomic settlement

A guarantee that a set of linked steps either all happen together or none happen at all. There is no half-finished state. 'Atomic' here means indivisible, not nuclear.

For example: Think of a vending machine that will not take your coin unless the drink is ready to drop. Either you get the drink and it gets the money, or nothing moves and you keep your coin. There is no state where it has your money and you have nothing.