Store useful client-side state with clear criteria: what to persist, how to serialize it and how to avoid inconsistent UI behavior.
Useful persistence is not the same as dumping everything into the browser.
Storage only keeps strings, so you control the conversion.
Saving objects means converting them with `JSON.stringify()`. Reading them back means handling `null` safely and parsing them with `JSON.parse()`.
This is also where defaults matter. If the key is missing or corrupted, the UI still needs a stable fallback.
Storage only becomes useful when it reconnects to the interface correctly.
A common pattern is to hydrate the UI on load and persist after each meaningful state change.
If the interface changes but you forget to save, the next reload will surprise the user with stale state.