Limits of JSON serialization for Pinia state backup in Vue 3

When persisting a Pinia store to browser storage for backup and later restoration, the goal is to re‑hydrate the store so that all state becomes reactive proxies and any class instances retain their methods after a page reload.

The process relies on JSON.stringify to serialize the store, which drops functions, class instances, circular references and private properties. Although toRaw can extract the underlying plain object for backup, Vue does not provide a built‑in mechanism to automatically re‑wrap that data into reactive proxies during restoration.

This leaves uncertainty about whether deep‑nested dependencies will correctly re‑link to the DOM and whether restored objects regain their original behavior without manual re‑wrapping.

What patterns exist to preserve class methods and reactivity through a JSON‑based backup‑restore cycle? How can developers verify that the restored state is fully reactive without manually converting each property?