diff --git a/dicom-viewer/src/App.tsx b/dicom-viewer/src/App.tsx
index 179d38a..51dae38 100644
--- a/dicom-viewer/src/App.tsx
+++ b/dicom-viewer/src/App.tsx
@@ -2545,27 +2545,68 @@ function App({ container_id, imageStacks, autoCacheStack, annotationJson, viewer
     };
 
     // Import and restore all annotations using cornerstoneTools.annotation.state.restoreAnnotations()
+    // Add defensive guards and queueing so callers can call importAnnotations before the
+    // viewer/annotation state is fully initialized in rare race conditions.
+    // @ts-expect-error window augmentation
+    window.__pendingImportAnnotations = window.__pendingImportAnnotations || {};
+    const flushPending = (key: string) => {
+      try {
+        // @ts-expect-error global
+        const pending = window.__pendingImportAnnotations && window.__pendingImportAnnotations[key];
+        if (!pending || !pending.length) return;
+        const annotationState = cornerstoneTools?.annotation?.state;
+        if (!annotationState || typeof annotationState.addAnnotation !== 'function') return;
+        // Drain the queue
+        while ((window.__pendingImportAnnotations[key] || []).length) {
+          const annotationData = (window.__pendingImportAnnotations[key] || []).shift();
+          if (!annotationData) continue;
+          if (Array.isArray(annotationData)) {
+            annotationData.forEach(ann => {
+              try { annotationState.addAnnotation(ann, ann.annotationUID); } catch (err) { console.error('Failed to add queued annotation', err, ann); }
+            });
+          }
+        }
+        if (renderingEngineRef.current) renderingEngineRef.current.render();
+      } catch (err) {
+        console.error('Error flushing pending annotations:', err);
+      }
+    };
+
+    // @ts-expect-error window augmentation
     window[`importAnnotations_${apiKey}`] = (json: string) => {
       try {
         const annotationData = typeof json === "string" ? JSON.parse(json) : json;
-        // Remove all existing annotations if needed
-        if (cornerstoneTools.annotation.state.removeAllAnnotations) {
-          cornerstoneTools.annotation.state.removeAllAnnotations();
+        const annotationState = cornerstoneTools?.annotation?.state;
+        if (!annotationState || typeof annotationState.addAnnotation !== 'function') {
+          // Queue the annotations until the annotation state is ready
+          // @ts-expect-error window augmentation
+          window.__pendingImportAnnotations[apiKey] = window.__pendingImportAnnotations[apiKey] || [];
+          window.__pendingImportAnnotations[apiKey].push(annotationData);
+          console.warn('importAnnotations: annotation state not ready, queued import', apiKey);
+          // schedule a flush attempt
+          setTimeout(() => flushPending(apiKey), 500);
+          return;
         }
-        // Add each annotation from the imported data
+
+        // Remove all existing annotations if needed
+        if (annotationState.removeAllAnnotations) {
+          try { annotationState.removeAllAnnotations(); } catch (err) { console.warn('removeAllAnnotations failed', err); }
+        }
+
         if (Array.isArray(annotationData)) {
-          // For now just add them to a new group
-          //const group = new cornerstoneTools.annotation.AnnotationGroup();
           annotationData.forEach(ann => {
-            cornerstoneTools.annotation.state.addAnnotation(ann, ann.annotationUID);
+            try { annotationState.addAnnotation(ann, ann.annotationUID); } catch (err) { console.error('Failed to add annotation', err, ann); }
           });
         }
         if (renderingEngineRef.current) {
           renderingEngineRef.current.render();
         }
       } catch (e) {
-        alert("Failed to import annotations: " + e);
+        console.error("Failed to import annotations:", e, { apiKey, cornerstoneTools: !!cornerstoneTools, renderingEngine: !!renderingEngineRef.current });
+        try { alert("Failed to import annotations: " + e); } catch (ignored) {}
       }
+      // Attempt to flush any queued imports (in case multiple imports were queued)
+      try { flushPending(apiKey); } catch (ignored) {}
     };
 
     window[`importLegacyAnnotations_${apiKey}`] = (json: string) => {