Yield recovery container encoding without changing durable cuts

src/lib/canvas-core/data-containers.ts

@@ -0,0 +1,10 @@
+// Private shape provenance: values may still be mutable and require capture.
+// Always copy; external Object.freeze is never accepted as ownership evidence.
+const owned = new WeakSet<object>();
+export function dataArray<T>(values: Iterable<T>): readonly T[] {
+  const result = Object.freeze(Array.from(values)); owned.add(result); return result;
+}
+export function dataRecord<T extends object>(value: T): Readonly<T> {
+  const result = Object.freeze({...value}); owned.add(result); return result;
+}
+export const isDataContainer = (value: object) => owned.has(value);