Function dispatch_untrusted_fan_in 

pub async fn dispatch_untrusted_fan_in(
    engine: &Arc<Mutex<SopEngine>>,
    audit: &SopAuditLogger,
    source: SopTriggerSource,
    topic: Option<&str>,
    payload: Option<&str>,
    dedup: Option<(String, bool)>,
) -> Vec<DispatchResult>

Compatibility wrapper for fan-in sources that already require concrete engine and audit handles. New or handle-optional sources should use SopIngress so missing handles and source-interest gating share one path.