It is tempting to build the screen first and figure out the data behind it later. It feels faster, right until you need a second way in.

The moment a mobile app, a partner integration or a reporting job needs the same data, a screen-first system has no clean way to give it. The logic is tangled into the interface, and every new client means copying it.

We design the api first. The rules live behind a stable contract, and the web screens are just one client of it. When the next client arrives, it plugs into the same contract.

This costs a little more thinking up front and saves a full rewrite later. The systems that age well are almost always the ones that decided their contracts early.