ok  Settings collect Client ID and Client secret instead of an Admin API token
ok  connection test requires store domain, Client ID, and Client secret
ok  token endpoint uses client_credentials against the shop domain
ok  portal obtains an Admin API token and uses it on subsequent requests
ok  cached token is reused until shortly before expiry
ok  expired tokens are renewed automatically
ok  stale Admin API tokens are refreshed and the product sync retried
ok  saving new Client ID or secret drops any cached Admin API token
ALL CHECKS PASSED