Value type emitted by the observable.
ReadonlycurrentDeep-cloned snapshot of the current signal value.
Subscribe to all value updates (including the current value immediately).
Callback invoked for each emitted value snapshot.
A Subscription used to stop observing updates.
Subscribe to the first non-nullish value, then auto-unsubscribe.
Callback invoked exactly once with the first non-nullish value.
A Subscription that can cancel before the first emission.
Minimal observable contract used by stateful Core signal streams.