cache warming

frontend/src/detail/DetailPanel.jsx

@@ -1106,6 +1106,56 @@ const DetailPanel = ({
     return () => window.removeEventListener('keydown', handleKeyDown);
   }, [zoomedPreview, zoomDisplay]);
 
+  useEffect(() => {
+    if (typeof ensureAssetUrl !== 'function') {
+      return;
+    }
+
+    const warmNavigator = (navigator) => {
+      const { documentId, asset, ordinal, canGoPrev, canGoNext } = navigator;
+      if (!documentId || !asset || !Number.isFinite(ordinal)) {
+        return;
+      }
+
+      const requests = [];
+      if (canGoPrev) {
+        const prevOrdinal = Math.max(1, ordinal - 1);
+        requests.push(
+          ensureAssetUrl(documentId, asset, {
+            start: prevOrdinal,
+            limit: 1,
+          }),
+        );
+      }
+      if (canGoNext) {
+        const nextOrdinal = ordinal + 1;
+        requests.push(
+          ensureAssetUrl(documentId, asset, {
+            start: nextOrdinal,
+            limit: 1,
+          }),
+        );
+      }
+
+      requests.forEach((promise) => promise?.catch?.(() => {}));
+    };
+
+    warmNavigator(singlePreviewNavigator);
+    warmNavigator(stackPreviewNavigator);
+  }, [
+    ensureAssetUrl,
+    singlePreviewNavigator.documentId,
+    singlePreviewNavigator.asset,
+    singlePreviewNavigator.ordinal,
+    singlePreviewNavigator.canGoPrev,
+    singlePreviewNavigator.canGoNext,
+    stackPreviewNavigator.documentId,
+    stackPreviewNavigator.asset,
+    stackPreviewNavigator.ordinal,
+    stackPreviewNavigator.canGoPrev,
+    stackPreviewNavigator.canGoNext,
+  ]);
+
   const zoomImageStyle = useMemo(() => {
     if (!zoomNative) {
       return {