Function ingress_kind 

pub fn ingress_kind(source: SopTriggerSource) -> SopIngressKind

Classify every SopTriggerSource as SopIngressKind::SharedIngress, SopIngressKind::DedicatedInternalDispatch, or SopIngressKind::NotYetLive.

Deliberately has NO wildcard arm: adding a new SopTriggerSource variant without classifying it here is a compile error. That compile-time failure is the drift guard - it forces a conscious decision about how a new trigger source enters (or does not yet enter) the SOP dispatch path, instead of silently falling through.