The welcome frame's keys replace the set pinned at enrolment, but only
over wss:// or loopback, the rule enrolment applies to the portal
address. Portal tokens are verified against the key their kid names, so
the hub can publish a new key beside the old one. A welcome without keys,
from an older hub, leaves the pinned set alone.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx