🚧 Signals

There is no fine-grained signals system (reactive cells that track dependencies and recompute derived values automatically). Reactivity in this SDK is immutable state plus events.

The scene is an immutable value: every operation (addElement, moveElement, …) returns a new scene plus a patch, and the editor swaps its _scene reference. Because each change produces a fresh object identity, observers can diff cheaply by reference.

The editor exposes a typed event surface (@oh-just-another/events). Subscribe to the whole change stream or to a single slice — slice events only fire when that slice's identity actually flips since the last notification:

const off = editor.on("selection", (sel) => {
  /* runs only when the selection changes */
});

const unsub = editor.subscribe(() => {
  /* runs on any scene / selection / mode / history change */
});

@oh-just-another/react-ui builds React bindings on this — useScene, useSelection, useMode, useHistory, useLayers, and useEditorSelector re-render a component only when the slice it reads changes.

Planned — not yet available: a dependency-tracking signals/computed primitive. If your framework provides signals (Solid, Preact, Vue refs), bridge them to editor.on(...) / editor.subscribe(...) — write the slice into your signal inside the listener.