State model

createControllableValue() is the only ownership primitive. In uncontrolled mode it stores the value internally. In controlled mode getValue() is authoritative, onValueChange() receives requests, and subscribeValue() invalidates the owning controller when the external store changes.

Updates carry a closed reason union and optional native event. Duplicate values do not notify. Re-entrant writes are queued and committed atomically. Snapshot arrays and plain-object records are recursively frozen before publication; DOM nodes and other class instances keep their platform identity and are not frozen. Listeners observe a deterministic sequence and may safely unsubscribe while publishing.

Controlled callbacks should update their external store synchronously or arrange for subscribeValue() to notify later. The runtime never invents an external value.