StairSmith

Claude and I did some App Store research together, looking for categories where people were paying for apps but the options were old, poorly reviewed, or both. Stair calculators fit the profile. A handful of apps, most untouched for years, and people clearly needed them.

We had a working app in a few days. A math engine with 120 tests covering building codes across four countries. Elevation diagrams. PDF cut sheets you can hand to someone at the saw. A framing square view that shows where to set the tongue and blade.

During QA I found that fractional inputs were silently wrong. 36.5 inches was becoming 37. A single line of formatting code was rounding everything before it reached the calculator. 120 tests passed. The bug was upstream of all of them.