_check_primary accepted any instance reporting status=ok and db=connected.
A local cache and the central hub both satisfied that for seven weeks while
every registration went to the cache — a liveness check wearing an authority
check's name.
It now requires the hub to declare instance_role=primary. An instance that
declares nothing is refused with a message naming what to set; proceeding
anyway requires an explicit --allow-unverified-primary rather than a silent
default.
Four tests cover the logic directly; the existing suite stubbed _check_primary
and never exercised it.
Refs CUST-WP-0067-T03
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 2583210@bnt-lap001
Assistant-Session: f2bff2d5-e9b2-4338-92ca-10282a927006
