Function run_case 

pub fn run_case(
    binary: &Path,
    workload_ref: &str,
    sandbox: &Path,
    label: &str,
    case: &VerifyCase,
) -> Result<(), String>

Run one case via <binary> run workload=… <args> --session-path … (under an in-process deadline) from sandbox, capture combined output, and check the rules. workload_ref is whatever goes after workload= — an absolute file path or a bundled catalog name; the subprocess resolves it exactly as a normal nmbrs run would.