Readonly[ReadonlytenantThis tenant's subscriptions for one provider (the host-DO rehydration query).
This tenant's subscriptions for one thread (the subscribe route's read).
Upsert a subscription (idempotent on provider × externalResourceId × thread).
Remove one subscription; true if a row was deleted.
The tenant-bound subscription store that keeps request scope isolated. Obtain via
SubscriptionStoreFactory.forTenant; the brand makes an unbound/system store a compile error where one of these is required.