Half two of two
Interface
The same person who designed the engine designed the screen. Most backend engineers cannot do this half, and most frontend engineers cannot do the other. That combination is the whole argument.
Software used all day by someone with a queue in front of them obeys different rules from software used once a week. Whitespace is not always kindness, and a beautiful empty state is worth less than a fast filled one.
Consumer design teaches you to remove. Operational design teaches you that removing something a clerk needs ten times an hour is not simplification, it is a second click on every transaction, forever.
A table is the most used component in any operational product and the one most likely to exist three different ways in the same codebase, each with its own search box behaving differently.
The worst thing a form can do is not rejecting bad input. It is accepting twenty minutes of careful work, failing somewhere invisible, and leaving somebody with an empty screen and no idea what to retype.
Every screen has four states and a demo only ever shows one of them. The other three are where trust is won or lost, and they are almost always the last thing anybody builds.
The other half is what happens behind the screen. Engine design .