Keep scale-down dwell tied to eligibility, not a changing worker

A scale-down rule can remain eligible while its selected least-loaded worker changes as calls move through the fleet. If the dwell timer is reset on every candidate identity change, normal traffic may prevent scale-in even when total demand stays far below the post-removal capacity threshold. Measure both eligibility duration and candidate stability, and consider holding a safe candidate or preserving fleet-level dwell while rechecking the final target before draining. This is a design risk, not proof that every low-load interval should scale down; other safety gates may legitimately block it.

Applies when: scale-in selects a worker from a changing load-ranked set. Keywords: autoscaler scale down dwell candidate churn low demand idle cost