Function record_handler_failure 

fn record_handler_failure(
    failure_dir: &Path,
    reverter: Address,
    selector: Selector,
    call_sequence: &[BaseCounterExample],
    settings: &InvariantSettings,
)

Persists a handler-side assertion bug under <failure_dir>/handlers/<site>.json, where <site> is keccak256(reverter || selector).