7e530dd09a
- CanvasArea: add useEffect to refresh InteractionEngine callbacks when props change - App.tsx: handleElementCreated/Deleted/Modified now use functional setElements updates - Root cause: CanvasArea init useEffect had empty deps, capturing stale callbacks at mount - handleElementCreated used [...elements, el] with stale elements=[] closure - Each new element replaced all previous ones instead of appending - All 343 tests pass, tsc clean