fix(P4A): ImageAnnotator effect-race — stabilize onCancel via ref so URL.revoke doesn't fire mid-decode

apps/desktop/src/components/ImageAnnotator.tsx

@@ -41,6 +41,15 @@ export function ImageAnnotator({ file, onCancel, onSave }: Props) {
   const draftRef = useRef<AnnotatorOp | null>(null);
   const [draftTick, setDraftTick] = useState(0);
 
+  // Hold a stable ref to onCancel so the image-load effect doesn't depend
+  // on its identity. Without this, parents that pass an inline `() => …`
+  // re-render the modal on every keystroke / state change, the effect re-
+  // runs, the previous URL.createObjectURL gets revoked WHILE the new img
+  // is still decoding → img.onerror fires ("file not found") → onCancel →
+  // modal flashes open + closes instantly.
+  const onCancelRef = useRef(onCancel);
+  useEffect(() => { onCancelRef.current = onCancel; }, [onCancel]);
+
   useEffect(() => {
     const url = URL.createObjectURL(file);
     const img = new Image();
@@ -50,11 +59,11 @@ export function ImageAnnotator({ file, onCancel, onSave }: Props) {
     };
     img.onerror = () => {
       console.error('ImageAnnotator: failed to decode source image');
-      onCancel();
+      onCancelRef.current();
     };
     img.src = url;
     return () => URL.revokeObjectURL(url);
-  }, [file, onCancel]);
+  }, [file]);
 
   useEffect(() => {
     if (!imageLoaded) return;