Hello,

Today, I released a new version of Valtio, v1.13.1. It slightly improves the Snapshot type. Valtio snapshots are read-only objects, so the types for snapshots are readonly as well. However, there are some exceptions, and ref() is one of them. Ref is an escape hatch to avoid creating snapshots, so we want to avoid making refs read-only. Roughly, here’s what I did:

type Snapshot<T> = T extends { $$valtioSnapshot: infer S } ? S : Readonly<T>;
declare function snapshot<T>(obj: T): Snapshot<T>;
declare function ref<T>(obj: T): T & { $$valtioSnapshot: T };

const x = snapshot({ a: 1 });
//    ^? const x: Readonly<{ a: number }>

const y = snapshot(ref({ a: 1 }));
//    ^? const y: { a: number }

TypeScript Playground: https://tsplay.dev/NrEeDw

This approach is so extensible that we could improve the type for other utils, namely proxySet and proxyMap.

Happy Hacking.

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