How to tell if it’s actually done.

The person who built it knows where to click. They know which button to avoid, which order to do things in, and what to type so it does not complain. Watching them use it proves almost nothing, because they steer round every problem without noticing they are doing it. After you have seen it a few times, the same is true of you.

Ask for somebody who has never seen it to try it from the very start, on their own, with nobody helping. Then ask what went wrong. Something always does, and it is far cheaper to hear about it now than from a customer.

The expensive failures are not the ones that put an error on the screen. They are the ones where the screen says it worked and it did not. A form says thank you and the message never arrives. A payment goes through and the order is never recorded. Everybody carries on, sometimes for months, until somebody notices the numbers do not add up.

Ask: when something goes wrong, how would we know? Who would be told, and how soon? A good answer names a person and the way they find out. “It will show an error” is not a good answer, because the worst failures never do.

A common way to see how something looks on a phone is to make a window on a computer narrow and look at that. It shows the layout. It does not show a phone: a thumb instead of a mouse, a keyboard that slides up and covers half the page, a weak signal on a bus, an older phone, slower than the one on your desk.

Things that look perfect in a narrow window regularly go wrong on a real phone, and usually at the moment somebody is trying to pay or sign up. Ask which actual phones it was tried on, and whether anybody used it one handed, away from a desk.

“It worked in testing” only means something once you know what the testing was. Three sample customers, or the thousands you really have? One person using it, or fifty at once? The real payment system, or a pretend one?

Plenty of work passes everything it was tried against and then meets conditions nobody tried. So when you are told something is ready, ask what it was tried against, and whether that looks like your real Monday morning. If nobody wrote those conditions down before the work began, the honest answer is that nobody knows yet.