The key of the last settlement this deployment completed.
Persisted for one reason: the convergence entry is the steady-state path,
so a fleet that reconciles on a schedule re-enters it forever. Without a
durable marker every one of those converges would re-fire settlement on an
unchanged deployment, and a host charging per settlement would charge per
reconcile. Absent on any deployment that has not settled since this field
existed, which reads as "settle once more", never as "already settled".
The key of the last settlement this deployment completed.
Persisted for one reason: the convergence entry is the steady-state path, so a fleet that reconciles on a schedule re-enters it forever. Without a durable marker every one of those converges would re-fire settlement on an unchanged deployment, and a host charging per settlement would charge per reconcile. Absent on any deployment that has not settled since this field existed, which reads as "settle once more", never as "already settled".