Editing while playing: play runs on a runtime copy, new Game tab (Scene | Game | Graph)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/runtime/Entity.ts

@@ -3,8 +3,9 @@ import type { PropertyBag } from '../core/model/Properties';
 
 /**
  * A live instance created from a scene object when Play starts. Holds the *resolved*
- * property values as mutable runtime state. Systems change entities freely; nothing here
- * is ever written back to the project model.
+ * property values as mutable runtime state. Systems change entities freely; the world
+ * mirrors them into the play-mode copy of the project (never the saved model) so the
+ * editor panels can show and edit them while playing.
  */
 export interface Entity {
   id: string;