Design pass: ten checks on a phone

A tool that works is not yet a tool someone will use. Before the capstone, run one design pass on the thing you shipped, on a phone, because that is where the person you built it for will open it. Ten checks, each a yes or a no: can you tell what it does in three seconds; is the first action obvious; does the main button sit under a thumb; does text stay readable without pinching; does anything scroll sideways; does an empty state say what to do; does an error say what went wrong and what to do next; does a slow step show it is working; can you get back without the browser button; does the page say who made it and how to reach them. Count the noes, pick the five that cost the most, fix them, and write one line per fix: what changed and why. The why is the artifact. A fix with no reason is a preference; a fix with a reason is a design decision you can defend to the next person who asks.