Function hydrate

packages/effect/src/unstable/reactivity/Hydration.ts:128–155

(
  registry: AtomRegistry.AtomRegistry,
  dehydratedState: Iterable<DehydratedAtom>
)

 * @since 4.0.0
 */
export const hydrate = (
  registry: AtomRegistry.AtomRegistry,
  dehydratedState: Iterable<DehydratedAtom>
): void => {
  for (const datom of (dehydratedState as Iterable<DehydratedAtomValue>)) {
    registry.setSerializable(datom.key, datom.value)

    // If there's a resultPromise, it means this was in Initial state when dehydrated
    // and we should wait for it to resolve to a non-Initial state, then update the registry
    if (!datom.resultPromise) continue
    datom.resultPromise.then((resolvedValue) => {
      // Try to update the existing node directly instead of using setSerializable
      const nodes = registry.getNodes()
      const node = nodes.get(datom.key)
      if (node) {
        // Decode the resolved value using the node's atom serializable decoder
        const atom = node.atom as any
        if (atom[Atom.SerializableTypeId]) {
          const decoded = atom[Atom.SerializableTypeId].decode(resolvedValue)
          ;(node as any).setValue(decoded)
        }
      } else {
        // Fallback to setSerializable if node doesn't exist yet
        registry.setSerializable(datom.key, resolvedValue)
      }
    })
  }
}