Local persistent key→bytes storage, scoped by app identity — private durable bytes no other app observes. For values shared with other apps, with change subscriptions, see documents.
Open this app's private store. The store follows the package: the same package reaches the same data across runs, instances, and versions, and no other app can address it. Distinct labels are independent stores; omitting the label opens the default store. Raises on an empty label.
Open the store named by uuid — any standard spelling, case-insensitive. Sharing is by knowledge: every app passing the same UUID reaches the same store, so treat an unpublished UUID as a secret. Raises when uuid is not a valid UUID.