🚧 Instance State

Instance state would be the per-editor, non-document state (current tool, camera, selection, hover) kept separate from the shared scene so two editors viewing the same document can have independent viewports and tools — and so it can be persisted per instance.

Planned — not yet available as a dedicated, named subsystem.

The pieces exist in @oh-just-another/state: the Editor holds the live mode (Mode), selection (Selection), and viewport, and @oh-just-another/scene defines the persistence scope for viewport vs document keys (VIEWPORT_SCOPE, SettingScope). A single unified "instance state" record and its serialization contract have not been formalized yet.