POST /v1/groups/ensure and /v1/groups/revoke: reserved prefixes refused, no
user creation, validate-before-mutate, read-back before success, delete only
empty groups on request. The oidc-browser-relying-party type now names them.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 5457@bnt-lap001
Assistant-Session: 792bf84a-3783-4f5d-a811-cded61dd2012