diff --git a/frontend/src/index.jsx b/frontend/src/index.jsx
index f93fbb7..59210e1 100644
--- a/frontend/src/index.jsx
+++ b/frontend/src/index.jsx
@@ -29,6 +29,7 @@ import TagsPanel from './tags/TagsPanel';
 import CorrespondentsPanel from './correspondents/CorrespondentsPanel';
 import TagManager from './tag_manager';
 import Sidebar from './sidebar/Sidebar';
+import SettingsModal from './settings/SettingsModal';
 import { ChevronsRightIcon } from './ui/icons';
 import { createDocumentsSurface } from './documents/DocumentsTable';
 import { createPreviewSurface } from './preview/PreviewWorkspace';
@@ -338,12 +339,12 @@ const LoginView = ({
             <div className="login-card__tenant-list">
               {tenantSelection.tenants.map((tenant) => (
                 <button
-                  key={tenant.tenant_id}
+                  key={tenant.id}
                   type="button"
                   onClick={() => onSelectTenant?.(tenant)}
                   disabled={Boolean(selectingTenantId)}
                   className={
-                    selectingTenantId === tenant.tenant_id
+                    selectingTenantId === tenant.id
                       ? 'login-card__tenant-button is-loading'
                       : 'login-card__tenant-button'
                   }
@@ -440,7 +441,7 @@ const AppLayout = () => {
   const previewDocumentId = routeDocumentId;
   const { status: appStatus, token, tenant, tenants: tenantOptions = [] } = appState;
   const tenantSlug = tenant?.slug || null;
-  const currentTenantId = tenant?.tenant_id || null;
+  const currentTenantId = tenant?.id || null;
   const [status, setStatus] = useState(null);
   const setStatusMessage = useCallback((message, variant = 'info') => {
     setStatus(message ? { message, variant } : null);
@@ -464,6 +465,7 @@ const AppLayout = () => {
   const [isCreateFolderModalOpen, setCreateFolderModalOpen] = useState(false);
   const [isTagsModalOpen, setTagsModalOpen] = useState(false);
   const [isCorrespondentsModalOpen, setCorrespondentsModalOpen] = useState(false);
+  const [isSettingsModalOpen, setSettingsModalOpen] = useState(false);
   const [newFolderName, setNewFolderName] = useState('');
   const [createFolderError, setCreateFolderError] = useState('');
   const [creatingFolder, setCreatingFolder] = useState(false);
@@ -2004,38 +2006,6 @@ const AppLayout = () => {
     ],
   );
 
-  const loadFolder = useCallback(
-    async (folderId, { showLoading = true, preserveSearch = false } = {}) => {
-      const targetId = folderId || 'root';
-      setSelectedFolder(targetId);
-      if (showLoading) setLoading(true);
-      try {
-        const contents = await ensureFolderData(targetId, { force: true, prefetchDepth: 1 });
-        if (targetId !== 'root') {
-          try {
-            await ensureFolderData('root', {
-              force: false,
-              includeDocuments: false,
-              prefetchDepth: 1,
-            });
-          } catch (error) {
-            console.warn('Failed to refresh root folder tree', error);
-          }
-        }
-        applySelectedFolder(targetId, contents);
-        if (!preserveSearch) {
-          setSearchResults(null);
-        }
-      } catch (error) {
-        notifyApiError(error, 'Failed to load folder contents.');
-      } finally {
-        if (showLoading) setLoading(false);
-      }
-    },
-    [ensureFolderData, applySelectedFolder, notifyApiError],
-  );
-
-
   const expandFolderAncestors = useCallback(
     (targetId) => {
       if (!targetId || targetId === 'root') {
@@ -2097,51 +2067,73 @@ const AppLayout = () => {
         return;
       }
 
-      const visited = new Set();
-      const stack = [];
-
-      let currentId = targetId;
-      let guard = 0;
-      while (currentId && currentId !== 'root' && guard < 32) {
-        guard += 1;
-        if (visited.has(currentId)) {
-          break;
-        }
-        visited.add(currentId);
-
-        const node = folderNodes.get(currentId);
-        if (!node) {
-          stack.push(currentId);
-          break;
+      const fetchAncestor = async (folderId, guard = 0) => {
+        if (!folderId || folderId === 'root' || guard > 32) {
+          return;
         }
 
-        const parentId = node.parentId ?? 'root';
-        if (!parentId || parentId === 'root') {
-          break;
+        const existing = folderNodes.get(folderId);
+        if (existing?.loaded) {
+          return;
         }
-        stack.push(parentId);
-        currentId = parentId;
-      }
 
-      while (stack.length) {
-        const ancestorId = stack.pop();
-        if (!ancestorId || ancestorId === 'root') {
-          continue;
+        try {
+          const contents = await ensureFolderData(folderId, {
+            includeDocuments: false,
+            force: false,
+            prefetchDepth: 0,
+          });
+          const parentId = contents?.folder?.parent_id ?? 'root';
+          if (parentId && parentId !== 'root') {
+            await fetchAncestor(parentId, guard + 1);
+          }
+        } catch (error) {
+          console.warn('Failed to ensure ancestor folder for navigation', folderId, error);
         }
-        if (!folderNodes.has(ancestorId)) {
+      };
+
+      await fetchAncestor(targetId, 0);
+    },
+    [folderNodes, ensureFolderData],
+  );
+
+  const loadFolder = useCallback(
+    async (folderId, { showLoading = true, preserveSearch = false } = {}) => {
+      const targetId = folderId || 'root';
+      setSelectedFolder(targetId);
+      await ensureFolderAncestorsLoaded(targetId);
+      expandFolderAncestors(targetId);
+      if (showLoading) setLoading(true);
+      try {
+        const contents = await ensureFolderData(targetId, { force: true, prefetchDepth: 1 });
+        if (targetId !== 'root') {
           try {
-            await ensureFolderData(ancestorId, {
-              includeDocuments: false,
+            await ensureFolderData('root', {
               force: false,
+              includeDocuments: false,
               prefetchDepth: 1,
             });
           } catch (error) {
-            console.warn('Failed to ensure ancestor folder for navigation', ancestorId, error);
+            console.warn('Failed to refresh root folder tree', error);
           }
         }
+        applySelectedFolder(targetId, contents);
+        if (!preserveSearch) {
+          setSearchResults(null);
+        }
+      } catch (error) {
+        notifyApiError(error, 'Failed to load folder contents.');
+      } finally {
+        if (showLoading) setLoading(false);
       }
     },
-    [folderNodes, ensureFolderData],
+    [
+      ensureFolderData,
+      applySelectedFolder,
+      notifyApiError,
+      ensureFolderAncestorsLoaded,
+      expandFolderAncestors,
+    ],
   );
 
   const selectFolder = useCallback(
@@ -2200,10 +2192,7 @@ const AppLayout = () => {
 
     const hasData = folderContents.has(targetParam);
     if (targetParam !== selectedFolder || !hasData) {
-      loadFolder(targetParam, {
-        showLoading: !routeDocumentId,
-        preserveSearch: isFilterActive,
-      });
+      selectFolder(targetParam, { immediate: true });
     }
   }, [
     token,
@@ -2211,9 +2200,9 @@ const AppLayout = () => {
     routeFolderId,
     routeDocumentId,
     selectedFolder,
-    loadFolder,
     folderContents,
     isFilterActive,
+    selectFolder,
   ]);
 
   const refreshCurrentFolder = useCallback(async () => {
@@ -4048,6 +4037,14 @@ const AppLayout = () => {
     setCorrespondentsModalOpen(false);
   }, []);
 
+  const openSettingsModal = useCallback(() => {
+    setSettingsModalOpen(true);
+  }, []);
+
+  const closeSettingsModal = useCallback(() => {
+    setSettingsModalOpen(false);
+  }, []);
+
   const handleCreateFolderSubmit = useCallback(
     async (event) => {
       event.preventDefault();
@@ -4111,10 +4108,11 @@ const AppLayout = () => {
   useEffect(() => {
     setTagsModalOpen(false);
     setCorrespondentsModalOpen(false);
+    setSettingsModalOpen(false);
   }, [location.pathname]);
 
   useEffect(() => {
-    if (!isTagsModalOpen && !isCorrespondentsModalOpen) {
+    if (!isTagsModalOpen && !isCorrespondentsModalOpen && !isSettingsModalOpen) {
       return;
     }
     const handleKeyDown = (event) => {
@@ -4124,6 +4122,8 @@ const AppLayout = () => {
           closeTagsModal();
         } else if (isCorrespondentsModalOpen) {
           closeCorrespondentsModal();
+        } else if (isSettingsModalOpen) {
+          closeSettingsModal();
         }
       }
     };
@@ -4131,7 +4131,14 @@ const AppLayout = () => {
     return () => {
       window.removeEventListener('keydown', handleKeyDown);
     };
-  }, [isTagsModalOpen, isCorrespondentsModalOpen, closeTagsModal, closeCorrespondentsModal]);
+  }, [
+    isTagsModalOpen,
+    isCorrespondentsModalOpen,
+    isSettingsModalOpen,
+    closeTagsModal,
+    closeCorrespondentsModal,
+    closeSettingsModal,
+  ]);
 
   useEffect(() => {
     if (!token) return undefined;
@@ -4943,8 +4950,7 @@ const AppLayout = () => {
 
   const handleTenantSelect = useCallback(
     async (tenantOption, { refreshOnly = false } = {}) => {
-      const requestedTenantId =
-        tenantOption?.tenant_id || tenantOption?.tenantId || tenantOption?.id || null;
+      const requestedTenantId = tenantOption?.id ?? null;
       if (!refreshOnly && (!requestedTenantId || requestedTenantId === currentTenantId)) {
         return;
       }
@@ -4980,7 +4986,7 @@ const AppLayout = () => {
 
         api.defaults.headers.common.Authorization = `Bearer ${data.access_token}`;
         tokenRef.current = data.access_token;
-        tenantIdRef.current = data?.tenant?.tenant_id || null;
+        tenantIdRef.current = data?.tenant?.id ?? null;
 
         if (Array.isArray(data?.tenants)) {
           appDispatch({ type: 'SET_TENANTS', tenants: data.tenants });
@@ -4992,10 +4998,8 @@ const AppLayout = () => {
         await Promise.all([refreshTags(), refreshCorrespondents()]);
         await loadFolder('root', { showLoading: false, preserveSearch: false });
 
-        setStatusMessage(
-          `Switched to ${data?.tenant?.slug || data?.tenant?.tenant_id || 'tenant'}.`,
-          'info',
-        );
+        const tenantLabel = data?.tenant?.slug || data?.tenant?.id || 'tenant';
+        setStatusMessage(`Switched to ${tenantLabel}.`, 'info');
       } catch (error) {
         notifyApiError(error, 'Failed to switch tenant.');
       } finally {
@@ -5102,6 +5106,7 @@ const AppLayout = () => {
     tenants: tenantOptions,
     activeTenantId: currentTenantId,
     onSelectTenant: handleTenantSelect,
+    onOpenSettings: openSettingsModal,
   };
 
   const sidebarPropsWithActions = useMemo(
@@ -5215,6 +5220,7 @@ const AppLayout = () => {
       resolveApiPath,
       openTagsModal,
       openCorrespondentsModal,
+      openSettingsModal,
     }),
     [
       token,
@@ -5255,6 +5261,7 @@ const AppLayout = () => {
       resolveApiPath,
       openTagsModal,
       openCorrespondentsModal,
+      openSettingsModal,
     ],
   );
 
@@ -5397,6 +5404,7 @@ const AppLayout = () => {
             </div>
           </div>
         )}
+        <SettingsModal open={isSettingsModalOpen} onClose={closeSettingsModal} />
       </div>
     </AppShellContext.Provider>
   );
@@ -5661,15 +5669,15 @@ const LoginRoute = () => {
 
   const handleTenantSelect = useCallback(
     async (tenant) => {
-      if (!tenantSelection?.selectionToken || !tenant?.tenant_id) {
+      if (!tenantSelection?.selectionToken || !tenant?.id) {
         return;
       }
 
       try {
-        setSelectingTenantId(tenant.tenant_id);
+        setSelectingTenantId(tenant.id);
         const { data } = await api.post(
           '/auth/select-tenant',
-          { tenant_id: tenant.tenant_id },
+          { tenant_id: tenant.id },
           {
             headers: {
               Authorization: `Bearer ${tenantSelection.selectionToken}`,
diff --git a/frontend/src/sidebar/Sidebar.jsx b/frontend/src/sidebar/Sidebar.jsx
index 2f6419b..ff58624 100644
--- a/frontend/src/sidebar/Sidebar.jsx
+++ b/frontend/src/sidebar/Sidebar.jsx
@@ -7,6 +7,8 @@ import {
   ChevronsLeftIcon,
   LogoutIcon,
   ChevronDownIcon,
+  SettingsIcon,
+  CheckIcon,
 } from '../ui/icons';
 
 import { getTagColorStyle } from '../utils/colors';
@@ -159,6 +161,7 @@ const Sidebar = ({
   tenants = [],
   activeTenantId = null,
   onSelectTenant,
+  onOpenSettings,
 }) => {
   const sortedCorrespondents = useMemo(
     () =>
@@ -232,7 +235,7 @@ const Sidebar = ({
 
   const handleTenantSelect = useCallback(
     (tenant) => {
-      const targetId = tenant?.tenant_id || tenant?.tenantId || tenant?.id || null;
+      const targetId = tenant?.id || null;
       if (!targetId) {
         return;
       }
@@ -247,6 +250,11 @@ const Sidebar = ({
     onLogout?.();
   }, [onLogout]);
 
+  const handleSettingsFromMenu = useCallback(() => {
+    setTenantMenuOpen(false);
+    onOpenSettings?.();
+  }, [onOpenSettings]);
+
   const renderNodes = useCallback(
     (ids, depth) =>
       ids.map((id) => {
@@ -317,7 +325,7 @@ const Sidebar = ({
                   <span className="menu__empty">No tenants available.</span>
                 ) : (
                   tenants.map((tenant) => {
-                    const tenantId = tenant?.tenant_id || tenant?.tenantId || tenant?.id || null;
+                    const tenantId = tenant?.id || null;
                     const isActive = tenantId === activeTenantId;
                     return (
                       <button
@@ -327,16 +335,26 @@ const Sidebar = ({
                         onClick={() => handleTenantSelect(tenant)}
                         role="menuitem"
                       >
+                        <span className="menu__check-slot">
+                          {isActive ? <CheckIcon size={16} /> : null}
+                        </span>
                         <span className="menu__label">
-                        {tenant?.slug || tenant?.name || tenantId || 'Tenant'}
+                          {tenant?.slug || tenant?.name || tenantId || 'Tenant'}
                         </span>
-                        {isActive ? <span className="menu__active-indicator">Active</span> : null}
                       </button>
                     );
                   })
                 )}
               </div>
               <div className="menu__footer">
+                <button
+                  type="button"
+                  className="menu__settings"
+                  onClick={handleSettingsFromMenu}
+                >
+                  <SettingsIcon size={16} />
+                  Settings
+                </button>
                 <button
                   type="button"
                   className="menu__logout"
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 2fc3828..feaf3c7 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -1191,7 +1191,7 @@ button.danger:hover:not([disabled]) {
 .menu .menu__item {
   display: flex;
   align-items: center;
-  justify-content: space-between;
+  justify-content: flex-start;
   gap: 0.6rem;
   width: 100%;
   padding: 0.55rem 1rem;
@@ -1230,6 +1230,14 @@ button.danger:hover:not([disabled]) {
   text-overflow: ellipsis;
 }
 
+.menu__check-slot {
+  width: 1rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: var(--accent, #2563eb);
+}
+
 .menu__active-indicator {
   font-size: 0.75rem;
   color: var(--muted);
@@ -1245,6 +1253,28 @@ button.danger:hover:not([disabled]) {
 .menu__footer {
   border-top: 1px solid var(--border-muted, var(--border));
   padding: 0.35rem 0.5rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+
+.menu__settings {
+  width: 100%;
+  display: inline-flex;
+  align-items: center;
+  gap: 0.4rem;
+  border: none;
+  background: none;
+  color: inherit;
+  font: inherit;
+  cursor: pointer;
+  padding: 0.4rem 0.5rem;
+  border-radius: 0.35rem;
+}
+
+.menu__settings:hover,
+.menu__settings:focus-visible {
+  background: var(--sidebar-hover-bg);
 }
 
 .menu__logout {
diff --git a/frontend/src/ui/icons.js b/frontend/src/ui/icons.js
index d5b123b..4b34f9b 100644
--- a/frontend/src/ui/icons.js
+++ b/frontend/src/ui/icons.js
@@ -21,6 +21,8 @@ import {
   IconLogout,
   IconChevronDown,
   IconX,
+  IconSettings,
+  IconCheck,
 } from '@tabler/icons-react';
 import FolderSvg from '../assets/folder.svg';
 
@@ -195,6 +197,24 @@ export const CloseIcon = ({ className, size = '1em', stroke = 1.6, ...rest }) =>
   />
 );
 
+export const SettingsIcon = ({ className, size = '1em', stroke = 1.6, ...rest }) => (
+  <IconSettings
+    className={composeClassName('icon', className)}
+    size={size}
+    stroke={stroke}
+    {...rest}
+  />
+);
+
+export const CheckIcon = ({ className, size = '1em', stroke = 1.6, ...rest }) => (
+  <IconCheck
+    className={composeClassName('icon', className)}
+    size={size}
+    stroke={stroke}
+    {...rest}
+  />
+);
+
 export const AnalyzeIcon = ({ className, size = '1em', stroke = 1.6, ...rest }) => (
   <IconAnalyze
     className={composeClassName('icon', className)}