An identity, a user or a service, registered in Polaris. The operator manages its lifecycle and writes the generated clientId/clientSecret to a Secret you name. You never set credentials yourself.
Same-namespace Secret name. The operator creates and owns this Secret, with a real owner reference, so it's garbage-collected when the principal is deleted.
The operator rotates the secret on its next reconcile and resets the field. Consumers reading the Secret at pod start (rather than caching the value) pick up the new credentials on their next restart.