fix breadcrumbs

frontend/src/index.jsx

@@ -1151,6 +1151,7 @@ function App({ routeFolderId = null, routeDocumentId = null, navigate }) {
   const documentDetailsRef = useRef(documentDetails);
   const tokenRef = useRef(token);
   const refreshPromiseRef = useRef(null);
+  const breadcrumbFetchRef = useRef(new Set());
   const refreshAccessToken = useCallback(async () => {
     console.log('[Auth] Attempting to refresh access token…');
     try {
@@ -3226,39 +3227,85 @@ const handleDownload = useCallback(
     });
   }, [selectionOrder, selectedDocumentIds, ensureDocumentDetail]);
 
-  const breadcrumbs = useMemo(() => {
+  const { breadcrumbs, missingBreadcrumbAncestors } = useMemo(() => {
     const chain = [];
     const seen = new Set();
+    const pending = new Set();
     let currentId = selectedFolder || 'root';
+    let guard = 0;
 
-    while (currentId && !seen.has(currentId)) {
+    while (currentId && !seen.has(currentId) && guard < 32) {
+      guard += 1;
       seen.add(currentId);
+
       if (currentId === 'root') {
         chain.push({ id: 'root', name: DEFAULT_FOLDER_NAME });
+        currentId = null;
         break;
       }
 
       const node = folderNodes.get(currentId);
       if (node) {
-        chain.push({ id: currentId, name: node.name || DEFAULT_FOLDER_NAME });
+        chain.push({ id: currentId, name: node.name || 'Folder' });
         currentId = node.parentId ?? 'root';
-      } else {
-        chain.push({ id: currentId, name: currentFolderName });
-        currentId = 'root';
+        continue;
       }
+
+      let fallbackName = '…';
+      let parentId = null;
+
+      if (currentFolder && currentFolder.id === currentId) {
+        fallbackName = currentFolder.name;
+        parentId = currentFolder.parent_id ?? 'root';
+      }
+
+      chain.push({ id: currentId, name: fallbackName });
+      pending.add(currentId);
+      currentId = parentId;
     }
 
-    if (chain[chain.length - 1]?.id !== 'root') {
+    if (!chain.some((crumb) => crumb.id === 'root')) {
       chain.push({ id: 'root', name: DEFAULT_FOLDER_NAME });
     }
 
-    return chain.reverse();
-  }, [selectedFolder, folderNodes, currentFolderName]);
+    const ordered = [];
+    const seenOrdered = new Set();
+    chain
+      .slice()
+      .reverse()
+      .forEach((crumb) => {
+        if (!seenOrdered.has(crumb.id)) {
+          seenOrdered.add(crumb.id);
+          ordered.push(crumb);
+        }
+      });
+
+    return { breadcrumbs: ordered, missingBreadcrumbAncestors: Array.from(pending) };
+  }, [selectedFolder, folderNodes, currentFolder]);
 
   useEffect(() => {
-    if (!selectedDocument) return;
-    ensurePreviewUrl(selectedDocument.id).catch(() => {});
-  }, [selectedDocument, ensurePreviewUrl]);
+    if (!missingBreadcrumbAncestors.length) {
+      return;
+    }
+
+    missingBreadcrumbAncestors.forEach((folderId) => {
+      if (!folderId || folderId === 'root') {
+        return;
+      }
+      if (breadcrumbFetchRef.current.has(folderId)) {
+        return;
+      }
+
+      breadcrumbFetchRef.current.add(folderId);
+      ensureFolderData(folderId, { force: false })
+        .catch((error) => {
+          console.warn('Failed to preload breadcrumb ancestor', folderId, error);
+        })
+        .finally(() => {
+          breadcrumbFetchRef.current.delete(folderId);
+        });
+    });
+  }, [missingBreadcrumbAncestors, ensureFolderData]);
 
   const selectedPreviewEntry = useMemo(() => {
     if (!selectedDocument) {