GetValue returns a transient view of the internal state. The view is valid only until the next write on the owner thread. Computations consume it; they must not retain it or mutate it. ASet.force materializes an immutable FrozenSet<'T> that is safe to retain; the library never touches a forced value again.

Derived sets are disposable: disposal unregisters the node from its dependencies and stops all delta processing. Disposing a changeable source is a no-op; sources are owned by the application. Dispose derived nodes before their consumers. Reading a disposed node throws.