Function prime_from_artifact_files 

fn prime_from_artifact_files(
    artifact_path: &Path,
    signature_path: &Path,
    trust_path: &Path,
    freshness_window: Duration,
) -> Option<(FleetResolved, String, Vec<u8>, Vec<u8>)>

File-fallback verify+parse for the –artifact / –signature CLI args. Synchronous; called once at startup before the listener opens. Hash is computed against the received bytes (not a re-serialised parsed struct) so additive schema changes the CP’s proto doesn’t yet know about don’t shift the rolloutId anchor — same load-bearing reason as in manifest_poll::poll_once.