Three intertwined changes, split by intent:
1. Swap AdminRoute for PermissionRoute on /settings, /groups/new, and
/groups/:id/edit. Admins retain full access; non-admin users whose
group holds settings:read / groups:create / groups:update can now
enter the respective pages instead of being silently redirected to
the dashboard. SettingsPage's individual tabs and cards keep their
existing per-action permission checks, so tabs a delegated user can't
use stay hidden or disabled. AdminRoute had no other callers and is
removed.
2. Fix#1083: editing a custom group's permissions appeared to revert
on reopen. The backend PATCH was persisting correctly — four new
integration tests in test_groups_api.py (including a direct DB read
after PATCH) confirm persistence, empty-list clear, preserve-on-
absent, and 400 on bogus permission. The actual bug was a stale
['group', id] React Query cache: onSuccess invalidated ['groups']
but not the detail key, so the 60s global staleTime served the pre-
update body on re-mount. onSuccess now primes ['group', id] with the
PATCH response body (invalidation is not enough — it races with the
refetch). Frontend regression test added.
3. Delegated users with settings:read but not settings:update no longer
get an infinite loop of failed-save toasts on Settings. The debounced
auto-save effect fires PATCH /settings whenever localSettings diverges
from the server snapshot; without a permission gate this produced an
endless 403 → toast → re-render → effect → 403 loop. Three gates now:
the updateSetting callback short-circuits with a single toast before
localSettings diverges, the effect safety-nets the same check in case
any call site bypasses updateSetting, and the language <select> (the
only direct api.updateSettings bypass in the file) now routes through
updateMutation with the same guard. New settings.toast.noPermissionUpdate
key translated in all 8 locales.
Scoping note: an earlier iteration of change #3 included a
localSettings rollback inside updateMutation.onError — removed in
review because it would have discarded in-progress admin typing on
any transient network/server error. The three up-front guards make
the rollback unnecessary for the permission case (mutation never
fires), and preserving typed-in values on transient failures is the
right call for admins.
