Snapshot Model

A Snapshot is the world state plus minimal kernel state, validated by Zod:

type Snapshot = {
  version: 1;
  meta: {
    tick: number;
    rng_state: number;
    rng_seed: number;
  };
  entities: ReadonlyArray<{ id: number; components: Record<string, unknown> }>;
  resources: Record<string, unknown>;
};

What’s captured

• Every entity that has at least one registered component, with its registered components serialized by name.
• Every registered resource by name.
• time.tick, rng.state(), and rng.seed.

What’s NOT captured (explicit policy)

• Components you didn’t register. (You opt in.)
• Resources you didn’t register.
• The schedule. (Code defines stages — restore loads data into a running schedule.)
• DOM, PIXI textures, runtime listeners, RAF handles, gamepad state.
• Anything in closures (system-internal let bindings, etc.).

The kernel state subset (tick, rng_state, rng_seed) is the minimum needed to replay deterministically from a save.