- principalFrom sets PreferredLocale from metadata admin_locale; personal
API token principals clear it, so token clients keep the request locale
- the guarded admin group runs locale.from-principal after the backend
guard, overriding the LocaleResolver or Accept-Language locale
- GET /lang honours a supported ?locale= and reports meta.locales
(cabana.LangEnvelope, cabana.LangMeta)
- Docker test for the override, refusals and /lang; docs and OpenAPI