prepare
fun <T : Any> prepare(identity: Long, key: RemoteStateKey<T>, create: () -> T, update: (T) -> Unit, release: (T) -> Unit = {})(source)
Creates or updates a typed presentation value from a registered preparation callback. release runs exactly once when the value is retired, including terminal failure cleanup. Creation and update callbacks cannot reenter preparation; closing from either callback invalidates this operation. A fresh factory result returned after close is released instead of admitted; callback failures remain primary.