Function run_validate_command 

pub fn run_validate_command(
    config_path: &str,
    export_name: Option<&str>,
    format: ValidateOutputFormat,
    target: ValidateTarget,
) -> Result<()>

Driver for rivet validate <export> (or every export when export_name is None).

Returns Err on the first explicit verification failure across the requested exports so an Airflow / CI step can branch on the exit code. Per-export verdicts are still printed to stdout / written to JSON for every export, including subsequent ones — the bail at the end is the last action.