Right now, when you accidentally reload you lose undo/redo state. Ideally undo/redo state is stored in an encoded form (MapData.toJSON) in localStorage and is therefore persisted after a reload, ensuring that players do not accidentally lose a map in progress. See the MapEditor component. It's also worth checking out the updateUndoStack function.

I suggest storing the undo state by mapObject?.id (or a fallback id if no mapObject is provided) so the undo stack can be per-map which will be on a different route in the game.

Additionally, when loading the map editor it has the ability to "restore" previous state, like from the last playtest. It should no longer be necessary to keep that feature separate, and instead the code should be cleaned up so that restorePreviousState just restores from the undo stack. This might need a fallback behavior so that it doesn't keep restoring the same previous map – or alternatively the "Restore Map" button in the MapEditorControlPanel should just be an "Undo" button after the first click (or after undo/redo is executed once). Open to ideas to ensure a good user experience.

Links

• Map Editor Playground