Function verify 

pub fn verify(record: &RunningRecord) -> Liveness

All three layers, door probe included.

The probe is one blocking GET /.well-known/agent-card.json, so this is callable from outside any async runtime. A record whose process is not ProcessState::Alive is answered without a probe, and so is a record with no door: its ProcessState::Alive process is Liveness::Live, with no connection made.