diff --git a/FEATURES.md b/FEATURES.md
index 6cd2dd36..cf7a1bde 100644
--- a/FEATURES.md
+++ b/FEATURES.md
@@ -69,6 +69,7 @@
 - Grid and list views with sorting by name, size, or date
 - Previews for images, text, audio, and video
 - Clipboard operations (cut, copy, paste, duplicate), favorites, and recent files
+- JMAP sharing (RFC 9670) for files and folders – share with users or groups at read, read/write, or manager levels via a principal picker, with share indicators and a "Shared with me" sidebar section for folders other principals have shared with you
 
 ## Security & Privacy
 
diff --git a/app/(main)/[locale]/files/page.tsx b/app/(main)/[locale]/files/page.tsx
index d1fe7ce8..4c3a5fad 100644
--- a/app/(main)/[locale]/files/page.tsx
+++ b/app/(main)/[locale]/files/page.tsx
@@ -22,6 +22,7 @@ import { useIsMobile } from "@/hooks/use-media-query";
 import { useRefreshGesture } from "@/hooks/use-refresh-gesture";
 import { usePolicyStore } from "@/stores/policy-store";
 import { FileBrowser } from "@/components/files/file-browser";
+import type { FileNodeRights } from "@/lib/jmap/types";
 import { ImagePreviewModal } from "@/components/files/image-preview-modal";
 import { FilePreviewModal } from "@/components/files/file-preview-modal";
 import { loadFilesSettings } from "@/components/files/files-settings-dialog";
@@ -88,6 +89,7 @@ export default function FilesPage() {
     cancelUpload,
     undoLastAction,
     lastAction,
+    shareResource,
   } = useFileStore();
 
   const isMobile = useIsMobile();
@@ -401,6 +403,14 @@ export default function FilesPage() {
 
   const currentFilesAccountId = useFileStore((s) => s.currentAccountId);
 
+  // Sharing: the browsing client (store-attached) drives the principal picker
+  // and share mutations. supportsPrincipals() gates the whole Share affordance.
+  const sharingEnabled = !!storeClient?.supportsPrincipals();
+  const filesAccountId = storeClient?.getFilesAccountId() ?? null;
+  const handleShare = useCallback(async (id: string, principalId: string, rights: FileNodeRights | null) => {
+    await shareResource(id, principalId, rights);
+  }, [shareResource]);
+
   // Pro shell only: all connected accounts are equal top-level entries at
   // the root. The root path "/" itself is a cross-account picker - no
   // account's files are shown until the user enters one.
@@ -540,6 +550,10 @@ export default function FilesPage() {
                   onSelectAccount={handleSelectAccount}
                   accountPickerMode={isAccountPicker}
                   accountLabel={currentAccountLabel}
+                  client={storeClient}
+                  ownAccountId={filesAccountId}
+                  sharingEnabled={sharingEnabled}
+                  onShare={handleShare}
                 />
                 </div>
               )}
diff --git a/components/files/file-browser.tsx b/components/files/file-browser.tsx
index 8399a612..b712c158 100644
--- a/components/files/file-browser.tsx
+++ b/components/files/file-browser.tsx
@@ -11,7 +11,7 @@ import {
   AlertCircle, Star, Clock, FolderUp,
   FileArchive, FileSpreadsheet, Presentation, FileCode,
   Box, PenTool, Terminal as TerminalIcon, Database, Type as TypeIcon,
-  Menu,
+  Menu, Users, Share2,
 } from "lucide-react";
 import { useIsDesktop } from "@/hooks/use-media-query";
 import { Button } from "@/components/ui/button";
@@ -26,6 +26,9 @@ import { ResizeHandle } from "@/components/layout/resize-handle";
 import { Avatar } from "@/components/ui/avatar";
 import { getDroppedFilesAndFolders } from "@/lib/webdav/drop-utils";
 import type { FileResource } from "@/stores/file-store";
+import { ShareCollectionDialog } from "@/components/settings/share-collection-dialog";
+import type { IJMAPClient } from "@/lib/jmap/client-interface";
+import type { FileNodeRights } from "@/lib/jmap/types";
 
 type SortKey = "name" | "size" | "modified";
 type SortDir = "asc" | "desc";
@@ -95,6 +98,14 @@ interface FileBrowserProps {
   accountPickerMode?: boolean;
   /** Pro shell only: label of the currently-attached account, shown as a breadcrumb segment after Home. */
   accountLabel?: string | null;
+  /** JMAP client for the browsing account, used by the share dialog to list principals. */
+  client?: IJMAPClient | null;
+  /** Files account id of the browsing account; used to exclude self from the share picker. */
+  ownAccountId?: string | null;
+  /** True when the server supports JMAP Sharing (principals); gates the Share action. */
+  sharingEnabled?: boolean;
+  /** Add/update/remove a principal's share on a node. Set null rights to revoke. */
+  onShare?: (id: string, principalId: string, rights: FileNodeRights | null) => Promise<void>;
 }
 
 const IMAGE_EXTENSIONS = new Set(["jpg", "jpeg", "png", "gif", "svg", "webp", "bmp", "ico", "avif"]);
@@ -230,6 +241,33 @@ function getGridIcon(resource: FileResource) {
   return getFileIconByName(resource.name, "lg");
 }
 
+// Small inline indicator: a node shared out by the user (shareWith has entries)
+// or a node shared *with* the user by another principal (isShared).
+function ShareBadge({ resource, t }: { resource: FileResource; t: (key: string) => string }) {
+  const sharedOut = !!resource.shareWith && Object.keys(resource.shareWith).length > 0;
+  if (resource.isShared) {
+    return (
+      <Share2
+        className="w-3.5 h-3.5 text-primary shrink-0"
+        aria-label={t("shared_with_me")}
+      >
+        <title>{t("shared_with_me")}</title>
+      </Share2>
+    );
+  }
+  if (sharedOut) {
+    return (
+      <Users
+        className="w-3.5 h-3.5 text-primary shrink-0"
+        aria-label={t("shared")}
+      >
+        <title>{t("shared")}</title>
+      </Users>
+    );
+  }
+  return null;
+}
+
 function Thumbnail({ name, getImageUrl: fetchUrl, size = "sm" }: {
   name: string;
   getImageUrl: (n: string) => Promise<string>;
@@ -342,11 +380,25 @@ export function FileBrowser({
   onSelectAccount,
   accountPickerMode,
   accountLabel,
+  client,
+  ownAccountId,
+  sharingEnabled,
+  onShare,
 }: FileBrowserProps) {
   const t = useTranslations("files");
   const [showNewFolder, setShowNewFolder] = useState(false);
   const [renameTarget, setRenameTarget] = useState<string | null>(null);
+  const [shareTargetId, setShareTargetId] = useState<string | null>(null);
   const [isDraggingOver, setIsDraggingOver] = useState(false);
+  // The share dialog is bound to a node id (not name) so its shareWith stays
+  // live after a share refresh re-derives the resource list.
+  const shareTarget = shareTargetId ? resources.find(r => r.id === shareTargetId) ?? null : null;
+  // A node is shareable when the server supports JMAP Sharing, the viewer owns
+  // it (not a shared-with-me node), and holds the mayShare right (owned nodes
+  // report full rights; treat missing myRights as allowed).
+  const canShare = useCallback((r: FileResource | null | undefined): boolean =>
+    !!(sharingEnabled && onShare && client && r && !r.isShared && (r.myRights?.mayShare ?? true)),
+    [sharingEnabled, onShare, client]);
   const [contextMenu, setContextMenu] = useState<{ x: number; y: number; name: string } | null>(null);
   const [emptyContextMenu, setEmptyContextMenu] = useState<{ x: number; y: number } | null>(null);
   const [showNewTextFile, setShowNewTextFile] = useState(false);
@@ -1440,8 +1492,9 @@ export function FileBrowser({
                     {showThumbnails && isImageFile(resource.name)
                       ? <Thumbnail name={resource.name} getImageUrl={getImageUrl} size="lg" />
                       : getGridIcon(resource)}
-                    <span className="text-xs truncate w-full text-center" title={resource.name}>
-                      {resource.name}
+                    <span className="text-xs truncate w-full text-center flex items-center justify-center gap-1" title={resource.name}>
+                      <span className="truncate">{resource.name}</span>
+                      <ShareBadge resource={resource} t={t} />
                     </span>
                   </div>
                 ))}
@@ -1590,6 +1643,7 @@ export function FileBrowser({
                         ? <Thumbnail name={resource.name} getImageUrl={getImageUrl} size="sm" />
                         : getFileIcon(resource)}
                       <span className="truncate">{resource.name}</span>
+                      <ShareBadge resource={resource} t={t} />
                     </div>
                   </td>
                   <td className="px-4 py-2.5 text-muted-foreground hidden md:table-cell tabular-nums">
@@ -1697,6 +1751,19 @@ export function FileBrowser({
                 {t("duplicate")}
               </button>
             )}
+            {canShare(resources.find(r => r.name === contextMenu.name)) && (
+              <button
+                className="w-full flex items-center gap-2 px-3 py-2 text-sm hover:bg-muted transition-colors text-left"
+                onClick={() => {
+                  const r = resources.find(res => res.name === contextMenu.name);
+                  if (r) setShareTargetId(r.id);
+                  setContextMenu(null);
+                }}
+              >
+                <Share2 className="w-4 h-4" />
+                {t("share")}
+              </button>
+            )}
             <div className="h-px bg-border my-1" />
             <button
               className="w-full flex items-center gap-2 px-3 py-2 text-sm hover:bg-muted transition-colors text-left"
@@ -1936,6 +2003,20 @@ export function FileBrowser({
           onCancel={() => setRenameTarget(null)}
         />
       )}
+
+      {/* Share dialog */}
+      {shareTarget && client && onShare && (
+        <ShareCollectionDialog
+          client={client}
+          kind="file"
+          collectionName={shareTarget.name}
+          shareWith={shareTarget.shareWith}
+          ownAccountId={ownAccountId || ""}
+          onShare={(principalId, rights) =>
+            onShare(shareTarget.id, principalId, rights as FileNodeRights | null)}
+          onClose={() => setShareTargetId(null)}
+        />
+      )}
     </div>
   );
 }
diff --git a/components/files/folder-tree-sidebar.tsx b/components/files/folder-tree-sidebar.tsx
index 48013f1c..1d7b0c94 100644
--- a/components/files/folder-tree-sidebar.tsx
+++ b/components/files/folder-tree-sidebar.tsx
@@ -8,6 +8,7 @@ import {
   ChevronRight,
   ChevronDown,
   Home,
+  Share2,
 } from "lucide-react";
 import { cn } from "@/lib/utils";
 import { useFileStore, type FileResource } from "@/stores/file-store";
@@ -29,6 +30,8 @@ interface FolderTreeSidebarProps {
 export function FolderTreeSidebar({ currentPath, onNavigate, listByParentId, width = 256, isResizing }: FolderTreeSidebarProps) {
   const t = useTranslations("files");
   const client = useFileStore(s => s.client);
+  const sharedRoots = useFileStore(s => s.sharedRoots);
+  const loadSharedRoots = useFileStore(s => s.loadSharedRoots);
   const [rootChildren, setRootChildren] = useState<FolderNode[] | null>(null);
   const [expandedIds, setExpandedIds] = useState<Set<string>>(new Set(["root"]));
   const [loadingIds, setLoadingIds] = useState<Set<string>>(new Set());
@@ -81,6 +84,8 @@ export function FolderTreeSidebar({ currentPath, onNavigate, listByParentId, wid
   useEffect(() => {
     if (client) {
       loadChildren(null, "/");
+      // Discover folders shared with the user by other principals.
+      loadSharedRoots();
     }
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [client]);
@@ -180,6 +185,40 @@ export function FolderTreeSidebar({ currentPath, onNavigate, listByParentId, wid
             />
           ))
         )}
+
+        {/* Shared with me: folders another principal has shared with the user */}
+        {sharedRoots.filter(r => r.isDirectory).length > 0 && (
+          <div className="mt-2 pt-2 border-t border-border/60">
+            <div className="px-3 py-1 text-[11px] font-medium uppercase tracking-wide text-muted-foreground flex items-center gap-1.5">
+              <Share2 className="w-3 h-3" />
+              <span className="truncate">{t("shared_with_me")}</span>
+            </div>
+            {sharedRoots.filter(r => r.isDirectory).map(r => {
+              const path = `/${r.name}`;
+              const isSelected = currentPath === path;
+              return (
+                <div
+                  key={r.id}
+                  style={{ paddingBlock: "var(--density-sidebar-py)" }}
+                  className={cn(
+                    "group w-full flex items-center max-lg:min-h-[44px] text-sm transition-all duration-200 px-2",
+                    isSelected ? "bg-accent text-accent-foreground" : "hover:bg-muted text-foreground"
+                  )}
+                >
+                  <button
+                    onClick={() => handleFolderClick(path, r.id)}
+                    className="flex items-center px-1 rounded transition-colors duration-150 flex-1 text-left min-w-0"
+                    style={{ paddingBlock: "var(--density-sidebar-py)", paddingLeft: "24px" }}
+                    title={r.ownerName ? t("shared_by", { name: r.ownerName }) : r.name}
+                  >
+                    <Folder className="w-4 h-4 flex-shrink-0 mr-2 text-primary" />
+                    <span className="truncate">{r.name}</span>
+                  </button>
+                </div>
+              );
+            })}
+          </div>
+        )}
       </div>
     </div>
   );
diff --git a/components/settings/share-collection-dialog.tsx b/components/settings/share-collection-dialog.tsx
index 7a3b9470..db64cd04 100644
--- a/components/settings/share-collection-dialog.tsx
+++ b/components/settings/share-collection-dialog.tsx
@@ -6,11 +6,11 @@ import { Button } from "@/components/ui/button";
 import { Avatar } from "@/components/ui/avatar";
 import { X, Loader2, UserPlus, Trash2, Users, ChevronDown } from "lucide-react";
 import type { IJMAPClient } from "@/lib/jmap/client-interface";
-import type { Principal, CalendarRights, AddressBookRights } from "@/lib/jmap/types";
+import type { Principal, CalendarRights, AddressBookRights, FileNodeRights } from "@/lib/jmap/types";
 import { toast } from "@/stores/toast-store";
 
-type ShareKind = "calendar" | "addressBook";
-type AnyRights = CalendarRights | AddressBookRights;
+type ShareKind = "calendar" | "addressBook" | "file";
+type AnyRights = CalendarRights | AddressBookRights | FileNodeRights;
 
 type RolePreset = "freeBusy" | "read" | "readWrite" | "manager" | "custom";
 
@@ -39,6 +39,21 @@ const ADDRESS_BOOK_PRESETS: Record<Exclude<RolePreset, "custom" | "freeBusy">, A
   manager: { mayRead: true, mayWrite: true, mayShare: true, mayDelete: true },
 };
 
+const FILE_PRESETS: Record<Exclude<RolePreset, "custom" | "freeBusy">, FileNodeRights> = {
+  read: {
+    mayRead: true, mayAddChildren: false, mayRename: false,
+    mayDelete: false, mayModifyContent: false, mayShare: false,
+  },
+  readWrite: {
+    mayRead: true, mayAddChildren: true, mayRename: true,
+    mayDelete: true, mayModifyContent: true, mayShare: false,
+  },
+  manager: {
+    mayRead: true, mayAddChildren: true, mayRename: true,
+    mayDelete: true, mayModifyContent: true, mayShare: true,
+  },
+};
+
 function detectCalendarPreset(r: CalendarRights): RolePreset {
   for (const [name, preset] of Object.entries(CALENDAR_PRESETS) as [Exclude<RolePreset, "custom">, CalendarRights][]) {
     if ((Object.keys(preset) as (keyof CalendarRights)[]).every((k) => preset[k] === r[k])) {
@@ -58,6 +73,29 @@ function detectAddressBookPreset(r: AddressBookRights): RolePreset {
   return "custom";
 }
 
+function detectFilePreset(r: FileNodeRights): RolePreset {
+  for (const [name, preset] of Object.entries(FILE_PRESETS) as [Exclude<RolePreset, "custom" | "freeBusy">, FileNodeRights][]) {
+    const keys = Object.keys(preset) as (keyof FileNodeRights)[];
+    if (keys.every((k) => preset[k] === (r[k] ?? false))) {
+      return name;
+    }
+  }
+  return "custom";
+}
+
+function presetRights(kind: ShareKind, preset: RolePreset): AnyRights | undefined {
+  if (preset === "custom") return undefined;
+  if (kind === "calendar") return CALENDAR_PRESETS[preset as keyof typeof CALENDAR_PRESETS];
+  if (kind === "file") return FILE_PRESETS[preset as keyof typeof FILE_PRESETS];
+  return ADDRESS_BOOK_PRESETS[preset as keyof typeof ADDRESS_BOOK_PRESETS];
+}
+
+function detectPreset(kind: ShareKind, rights: AnyRights): RolePreset {
+  if (kind === "calendar") return detectCalendarPreset(rights as CalendarRights);
+  if (kind === "file") return detectFilePreset(rights as FileNodeRights);
+  return detectAddressBookPreset(rights as AddressBookRights);
+}
+
 interface ShareCollectionDialogProps {
   client: IJMAPClient;
   kind: ShareKind;
@@ -126,9 +164,7 @@ export function ShareCollectionDialog({
 
   const handleSetRights = async (principalId: string, preset: RolePreset) => {
     if (preset === "custom") return; // custom is read-only here
-    const rights = kind === "calendar"
-      ? CALENDAR_PRESETS[preset as keyof typeof CALENDAR_PRESETS]
-      : ADDRESS_BOOK_PRESETS[preset as keyof typeof ADDRESS_BOOK_PRESETS];
+    const rights = presetRights(kind, preset);
     if (!rights) return;
     setSavingId(principalId);
     try {
@@ -154,10 +190,8 @@ export function ShareCollectionDialog({
   };
 
   const handleAdd = async (principal: Principal) => {
-    const defaultPreset: RolePreset = "read";
-    const rights = kind === "calendar"
-      ? CALENDAR_PRESETS[defaultPreset]
-      : ADDRESS_BOOK_PRESETS[defaultPreset];
+    const rights = presetRights(kind, "read");
+    if (!rights) return;
     setSavingId(principal.id);
     try {
       await onShare(principal.id, rights);
@@ -226,9 +260,7 @@ export function ShareCollectionDialog({
             <ul className="divide-y divide-border rounded-md border border-border overflow-hidden">
               {sharedEntries.map(([principalId, rights]) => {
                 const principal = allPrincipalsById.get(principalId);
-                const preset = kind === "calendar"
-                  ? detectCalendarPreset(rights as CalendarRights)
-                  : detectAddressBookPreset(rights as AddressBookRights);
+                const preset = detectPreset(kind, rights);
                 return (
                   <li key={principalId} className="flex items-center gap-3 px-3 py-2.5">
                     <Avatar
diff --git a/lib/__tests__/jmap-file-share.test.ts b/lib/__tests__/jmap-file-share.test.ts
new file mode 100644
index 00000000..e327130e
--- /dev/null
+++ b/lib/__tests__/jmap-file-share.test.ts
@@ -0,0 +1,92 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { JMAPClient } from '../jmap/client';
+import type { FileNodeRights } from '../jmap/types';
+
+function createClient(): JMAPClient {
+  const client = new JMAPClient('https://jmap.example.com', 'user', 'pass');
+  Object.assign(client, {
+    apiUrl: 'https://jmap.example.com/api',
+    accountId: 'account-1',
+    capabilities: { 'urn:ietf:params:jmap:filenode': {}, 'urn:ietf:params:jmap:principals': {} },
+  });
+  return client;
+}
+
+function mockFetch(response: object, ok = true, status = 200) {
+  return vi.spyOn(globalThis, 'fetch').mockResolvedValue({
+    ok,
+    status,
+    text: () => Promise.resolve(JSON.stringify(response)),
+    json: () => Promise.resolve(response),
+  } as Response);
+}
+
+const READ: FileNodeRights = {
+  mayRead: true, mayAddChildren: false, mayRename: false,
+  mayDelete: false, mayModifyContent: false, mayShare: false,
+};
+
+function lastRequestBody(spy: ReturnType<typeof vi.spyOn>): { using: string[]; methodCalls: unknown[][] } {
+  const call = spy.mock.calls[spy.mock.calls.length - 1];
+  return JSON.parse((call[1] as RequestInit).body as string);
+}
+
+describe('JMAPClient.setFileNodeShare', () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('sends a FileNode/set shareWith patch and resolves on success', async () => {
+    const spy = mockFetch({
+      methodResponses: [['FileNode/set', { updated: { 'node-1': null } }, '0']],
+    });
+    const client = createClient();
+
+    await client.setFileNodeShare('node-1', 'principal-9', READ);
+
+    const body = lastRequestBody(spy);
+    expect(body.using).toContain('urn:ietf:params:jmap:filenode');
+    expect(body.using).toContain('urn:ietf:params:jmap:principals:owner');
+    const [method, args] = body.methodCalls[0] as [string, Record<string, unknown>];
+    expect(method).toBe('FileNode/set');
+    expect(args.accountId).toBe('account-1');
+    expect(args.update).toEqual({
+      'node-1': { 'shareWith/principal-9': READ },
+    });
+  });
+
+  it('sends null to revoke a principal\'s access', async () => {
+    const spy = mockFetch({
+      methodResponses: [['FileNode/set', { updated: { 'node-1': null } }, '0']],
+    });
+    const client = createClient();
+
+    await client.setFileNodeShare('node-1', 'principal-9', null);
+
+    const body = lastRequestBody(spy);
+    const [, args] = body.methodCalls[0] as [string, Record<string, unknown>];
+    expect(args.update).toEqual({ 'node-1': { 'shareWith/principal-9': null } });
+  });
+
+  it('throws with the server description when the update is rejected', async () => {
+    mockFetch({
+      methodResponses: [['FileNode/set', {
+        notUpdated: { 'node-1': { type: 'forbidden', description: 'Not allowed' } },
+      }, '0']],
+    });
+    const client = createClient();
+
+    await expect(client.setFileNodeShare('node-1', 'principal-9', READ))
+      .rejects.toThrow('Not allowed');
+  });
+
+  it('throws when the server does not confirm the update', async () => {
+    mockFetch({
+      methodResponses: [['FileNode/set', { updated: {} }, '0']],
+    });
+    const client = createClient();
+
+    await expect(client.setFileNodeShare('node-1', 'principal-9', READ))
+      .rejects.toThrow('did not confirm');
+  });
+});
diff --git a/lib/demo/demo-client.ts b/lib/demo/demo-client.ts
index 0d4a9456..edd0e93e 100644
--- a/lib/demo/demo-client.ts
+++ b/lib/demo/demo-client.ts
@@ -912,6 +912,12 @@ export class DemoJMAPClient implements IJMAPClient {
     return [...this.data.fileNodes];
   }
 
+  async listAllFileNodesAcrossAccounts(): Promise<FileNode[]> {
+    return [...this.data.fileNodes];
+  }
+
+  async setFileNodeShare(): Promise<void> { /* demo: no-op */ }
+
   async getFileNodes(ids: string[] | null): Promise<FileNode[]> {
     if (ids === null) return [...this.data.fileNodes];
     return this.data.fileNodes.filter(n => ids.includes(n.id));
diff --git a/lib/jmap/client-interface.ts b/lib/jmap/client-interface.ts
index 06926548..c2715d1e 100644
--- a/lib/jmap/client-interface.ts
+++ b/lib/jmap/client-interface.ts
@@ -1,4 +1,4 @@
-import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, AddressBookRights, VacationResponse, Calendar, CalendarRights, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode, Principal, PushSubscription, ScheduledEmail, SendEmailResult } from "./types";
+import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, AddressBookRights, VacationResponse, Calendar, CalendarRights, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode, FileNodeRights, Principal, PushSubscription, ScheduledEmail, SendEmailResult } from "./types";
 import type { SieveScript, SieveCapabilities } from "./sieve-types";
 
 /**
@@ -292,6 +292,7 @@ export interface IJMAPClient {
   getPrincipals(targetAccountId?: string): Promise<Principal[]>;
   setCalendarShare(calendarId: string, principalId: string, rights: CalendarRights | null, targetAccountId?: string): Promise<void>;
   setAddressBookShare(addressBookId: string, principalId: string, rights: AddressBookRights | null, targetAccountId?: string): Promise<void>;
+  setFileNodeShare(fileNodeId: string, principalId: string, rights: FileNodeRights | null, targetAccountId?: string): Promise<void>;
 
   // ── Sieve / Filters ──────────────────────────────────────────
   getSieveAccountId(): string;
@@ -308,6 +309,7 @@ export interface IJMAPClient {
   probeFileNodeSupport(): Promise<boolean>;
   listFileNodes(parentId: string | null): Promise<FileNode[]>;
   listAllFileNodes(): Promise<FileNode[]>;
+  listAllFileNodesAcrossAccounts(): Promise<FileNode[]>;
   getFileNodes(ids: string[] | null, properties?: string[]): Promise<FileNode[]>;
   createFileDirectory(name: string, parentId: string | null): Promise<FileNode>;
   createFileNode(name: string, blobId: string, type: string, size: number, parentId: string | null): Promise<FileNode>;
diff --git a/lib/jmap/client.ts b/lib/jmap/client.ts
index 8aa1772c..a075d9f9 100644
--- a/lib/jmap/client.ts
+++ b/lib/jmap/client.ts
@@ -1,4 +1,4 @@
-import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, AddressBookRights, VacationResponse, Calendar, CalendarRights, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode, FileNodeFilter, Principal, PushSubscription, EmailSubmission, ScheduledEmail, SendEmailResult } from "./types";
+import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, AddressBookRights, VacationResponse, Calendar, CalendarRights, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode, FileNodeFilter, FileNodeRights, Principal, PushSubscription, EmailSubmission, ScheduledEmail, SendEmailResult } from "./types";
 import type { SieveScript, SieveCapabilities } from "./sieve-types";
 import type { IJMAPClient } from "./client-interface";
 import { toWildcardQuery } from "./search-utils";
@@ -5073,10 +5073,37 @@ export class JMAPClient implements IJMAPClient {
     if (this.hasCapability("urn:ietf:params:jmap:filenode")) {
       using.push("urn:ietf:params:jmap:filenode");
     }
+    // Required for shareWith/myRights on FileNode and for cross-account
+    // (shared-with-me) FileNode/get, mirroring calendarUsing().
+    if (this.supportsPrincipals()) {
+      using.push("urn:ietf:params:jmap:principals:owner");
+    }
     return using;
   }
 
-  private static FILE_NODE_PROPERTIES = ["id", "parentId", "name", "type", "blobId", "size", "created", "updated"];
+  private static FILE_NODE_PROPERTIES = [
+    "id", "parentId", "name", "type", "blobId", "size", "created", "updated",
+    // Stalwart omits shareWith/myRights from FileNode/get unless requested
+    // explicitly, so the share dialog and indicators can't see existing
+    // shares without naming them here (same as CALENDAR_PROPERTIES).
+    "shareWith", "myRights",
+  ];
+
+  // Accounts (primary + shared/group) that can hold FileNodes. Mirrors
+  // getCalendarCapableAccountIds(): includes any non-primary account that
+  // advertises the filenode capability or is a non-personal (shared/group)
+  // account, since Stalwart doesn't always advertise capabilities on those.
+  private getFilesCapableAccountIds(): string[] {
+    const primaryId = this.getFilesAccountId();
+    const accountIds: string[] = [];
+    for (const [id, account] of Object.entries(this.accounts)) {
+      if (id === primaryId) continue;
+      if (account.accountCapabilities?.["urn:ietf:params:jmap:filenode"] || !account.isPersonal) {
+        accountIds.push(id);
+      }
+    }
+    return [primaryId, ...accountIds];
+  }
 
   async getFileNodes(ids: string[] | null, properties?: string[]): Promise<FileNode[]> {
     const accountId = this.getFilesAccountId();
@@ -5143,6 +5170,79 @@ export class JMAPClient implements IJMAPClient {
     return (getResult[1].list || []) as FileNode[];
   }
 
+  /**
+   * Fetch every FileNode the logged-in user can see across all connected and
+   * shared accounts. Nodes owned by another principal (shared with the user)
+   * are tagged with `isShared: true` and the owning `accountId`/`accountName`,
+   * and their ids are namespaced `accountId:nodeId` so they don't collide with
+   * the primary account's ids. Mirrors getAllCalendars().
+   */
+  async listAllFileNodesAcrossAccounts(): Promise<FileNode[]> {
+    const primaryId = this.getFilesAccountId();
+    const accountIds = this.getFilesCapableAccountIds();
+    const all: FileNode[] = [];
+
+    for (const accountId of accountIds) {
+      const isPrimary = accountId === primaryId;
+      const account = this.accounts[accountId];
+      try {
+        const response = await this.request(
+          [["FileNode/get", { accountId, ids: null, properties: JMAPClient.FILE_NODE_PROPERTIES }, "fng0"]],
+          this.fileUsing(),
+        );
+        const getResult = response.methodResponses?.find(r => r[0] === "FileNode/get");
+        if (!getResult || getResult[0] === "error") continue;
+        const nodes = (getResult[1].list || []) as FileNode[];
+        for (const node of nodes) {
+          all.push({
+            ...node,
+            id: isPrimary ? node.id : `${accountId}:${node.id}`,
+            parentId: node.parentId == null
+              ? null
+              : (isPrimary ? node.parentId : `${accountId}:${node.parentId}`),
+            accountId,
+            accountName: account?.name || (isPrimary ? this.username : accountId),
+            isShared: !isPrimary,
+          });
+        }
+      } catch (error) {
+        console.error(`[Files] Failed to fetch FileNodes for account ${accountId}:`, error);
+      }
+    }
+
+    return all;
+  }
+
+  /**
+   * Add, update, or remove a principal's rights on a FileNode (file or folder).
+   * Pass `rights: null` to revoke access. Mirrors setCalendarShare /
+   * setAddressBookShare; Stalwart applies it via a `shareWith/{principalId}`
+   * patch on FileNode/set.
+   */
+  async setFileNodeShare(
+    fileNodeId: string,
+    principalId: string,
+    rights: FileNodeRights | null,
+    targetAccountId?: string,
+  ): Promise<void> {
+    const accountId = targetAccountId || this.getFilesAccountId();
+    const response = await this.request([
+      ["FileNode/set", {
+        accountId,
+        update: { [fileNodeId]: { [`shareWith/${principalId}`]: rights } },
+      }, "0"],
+    ], this.fileUsing());
+
+    const result = response.methodResponses?.[0]?.[1];
+    if (result?.notUpdated?.[fileNodeId]) {
+      const err = result.notUpdated[fileNodeId];
+      throw new Error(err.description || "Failed to update file share");
+    }
+    if (!result?.updated || !(fileNodeId in result.updated)) {
+      throw new Error("Server did not confirm the share update");
+    }
+  }
+
   async createFileDirectory(name: string, parentId: string | null): Promise<FileNode> {
     const accountId = this.getFilesAccountId();
 
diff --git a/lib/jmap/types.ts b/lib/jmap/types.ts
index ec65774b..c69d3be0 100644
--- a/lib/jmap/types.ts
+++ b/lib/jmap/types.ts
@@ -792,6 +792,32 @@ export interface FileNode {
   size: number;
   created: string;
   updated: string;
+  // JMAP Sharing (RFC 9670). Populated only when the server advertises the
+  // filenode capability and the properties are explicitly requested. A node is
+  // shared-out when `shareWith` has entries; `myRights` describes what the
+  // viewer may do (always full rights on owned nodes).
+  myRights?: FileNodeRights;
+  shareWith?: Record<string, FileNodeRights> | null;
+  // True when this node was fetched from another principal's account that was
+  // shared with the logged-in user (mirrors Calendar.isShared / AddressBook.isShared).
+  isShared?: boolean;
+  // Owning account's JMAP id and display name, set when aggregating nodes
+  // across connected/shared accounts so mutations route to the right account.
+  accountId?: string;
+  accountName?: string;
+  // Local account-store id (per JMAP connection) in multi-account contexts.
+  // See Calendar.localAccountId.
+  localAccountId?: string;
+}
+
+// FileNode rights as defined by Stalwart's JmapSharedObject implementation.
+export interface FileNodeRights {
+  mayRead: boolean;
+  mayAddChildren: boolean;
+  mayRename: boolean;
+  mayDelete: boolean;
+  mayModifyContent: boolean;
+  mayShare: boolean;
 }
 
 export interface FileNodeFilter {
diff --git a/locales/cs/common.json b/locales/cs/common.json
index 4c8ffba1..45d9a8c7 100644
--- a/locales/cs/common.json
+++ b/locales/cs/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplikovat",
     "duplicate_success": "Úspěšně duplikováno",
     "duplicate_error": "Duplikování selhalo",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Soubor byl vytvořen",
     "create_file_error": "Vytvoření souboru selhalo",
     "favorites": "Oblíbené",
diff --git a/locales/da/common.json b/locales/da/common.json
index d0a1e6f8..46d5230d 100644
--- a/locales/da/common.json
+++ b/locales/da/common.json
@@ -2944,6 +2944,10 @@
     "duplicate": "Duplikér",
     "duplicate_success": "Duplikeret",
     "duplicate_error": "Kunne ikke duplikere",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Fil oprettet",
     "create_file_error": "Kunne ikke oprette fil",
     "favorites": "Favoritter",
diff --git a/locales/de/common.json b/locales/de/common.json
index 38bbf347..3634c04f 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplizieren",
     "duplicate_success": "Erfolgreich dupliziert",
     "duplicate_error": "Duplizieren fehlgeschlagen",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Datei erstellt",
     "create_file_error": "Datei konnte nicht erstellt werden",
     "favorites": "Favoriten",
diff --git a/locales/en/common.json b/locales/en/common.json
index fba1e9ff..aecc09ff 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -2946,6 +2946,10 @@
     "duplicate": "Duplicate",
     "duplicate_success": "Duplicated successfully",
     "duplicate_error": "Failed to duplicate",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "File created",
     "create_file_error": "Failed to create file",
     "favorites": "Favorites",
diff --git a/locales/es/common.json b/locales/es/common.json
index b117dc99..9fce4e64 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplicar",
     "duplicate_success": "Duplicado correctamente",
     "duplicate_error": "Error al duplicar",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Archivo creado",
     "create_file_error": "Error al crear el archivo",
     "favorites": "Favoritos",
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 55086fa8..4dce8ac6 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Dupliquer",
     "duplicate_success": "Dupliqué avec succès",
     "duplicate_error": "Échec de la duplication",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Fichier créé",
     "create_file_error": "Échec de la création du fichier",
     "favorites": "Favoris",
diff --git a/locales/hu/common.json b/locales/hu/common.json
index 3abc697a..a7a0a08e 100644
--- a/locales/hu/common.json
+++ b/locales/hu/common.json
@@ -2946,6 +2946,10 @@
     "duplicate": "Duplikálás",
     "duplicate_success": "Sikeresen duplikálva",
     "duplicate_error": "Nem sikerült duplikálni",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Fájl létrehozva",
     "create_file_error": "Nem sikerült létrehozni a fájlt",
     "favorites": "Kedvencek",
diff --git a/locales/it/common.json b/locales/it/common.json
index 84398dc7..1aea1658 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplica",
     "duplicate_success": "Duplicato con successo",
     "duplicate_error": "Duplicazione non riuscita",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "File creato",
     "create_file_error": "Creazione del file non riuscita",
     "favorites": "Preferiti",
diff --git a/locales/ja/common.json b/locales/ja/common.json
index 3145ed6c..a1bae1ee 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "複製",
     "duplicate_success": "正常に複製しました",
     "duplicate_error": "複製に失敗しました",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "ファイルを作成しました",
     "create_file_error": "ファイルの作成に失敗しました",
     "favorites": "お気に入り",
diff --git a/locales/ko/common.json b/locales/ko/common.json
index 56cfb729..c8d35250 100644
--- a/locales/ko/common.json
+++ b/locales/ko/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "복제",
     "duplicate_success": "성공적으로 복제되었어요",
     "duplicate_error": "복제에 실패했어요",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "파일이 만들어졌어요",
     "create_file_error": "파일을 만들지 못했어요",
     "favorites": "즐겨찾기",
diff --git a/locales/lv/common.json b/locales/lv/common.json
index f69d9984..bafc37b8 100644
--- a/locales/lv/common.json
+++ b/locales/lv/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Dublēt",
     "duplicate_success": "Dublēšana pabeigta",
     "duplicate_error": "Neizdevās dublēt",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Fails izveidots",
     "create_file_error": "Neizdevās izveidot failu",
     "favorites": "Izlase",
diff --git a/locales/nl/common.json b/locales/nl/common.json
index 4412ccbd..ef9fb760 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Dupliceren",
     "duplicate_success": "Succesvol gedupliceerd",
     "duplicate_error": "Dupliceren mislukt",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Bestand aangemaakt",
     "create_file_error": "Bestand aanmaken mislukt",
     "favorites": "Favorieten",
diff --git a/locales/pl/common.json b/locales/pl/common.json
index 17804a80..4ba6f76d 100644
--- a/locales/pl/common.json
+++ b/locales/pl/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplikuj",
     "duplicate_success": "Zduplikowano pomyślnie",
     "duplicate_error": "Nie udało się zduplikować",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Plik utworzono",
     "create_file_error": "Nie udało się utworzyć pliku",
     "favorites": "Ulubione",
diff --git a/locales/pt/common.json b/locales/pt/common.json
index c78fd3d0..f07df2e2 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Duplicar",
     "duplicate_success": "Duplicado com sucesso",
     "duplicate_error": "Falha ao duplicar",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Arquivo criado",
     "create_file_error": "Falha ao criar arquivo",
     "favorites": "Favoritos",
diff --git a/locales/ru/common.json b/locales/ru/common.json
index e62089fd..388a0480 100644
--- a/locales/ru/common.json
+++ b/locales/ru/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "Дублировать",
     "duplicate_success": "Дублирование выполнено успешно",
     "duplicate_error": "Не удалось дублировать",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Файл создан",
     "create_file_error": "Не удалось создать файл",
     "favorites": "Избранное",
diff --git a/locales/tr/common.json b/locales/tr/common.json
index 7d3fd075..e44217cc 100644
--- a/locales/tr/common.json
+++ b/locales/tr/common.json
@@ -2944,6 +2944,10 @@
     "duplicate": "Çoğalt",
     "duplicate_success": "Başarıyla çoğaltıldı",
     "duplicate_error": "Çoğaltılamadı",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Dosya oluşturuldu",
     "create_file_error": "Dosya oluşturulamadı",
     "favorites": "Favoriler",
diff --git a/locales/uk/common.json b/locales/uk/common.json
index 37d1d9a6..9b5443a5 100644
--- a/locales/uk/common.json
+++ b/locales/uk/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "дублікат",
     "duplicate_success": "Продубльовано успішно",
     "duplicate_error": "Не вдалося скопіювати",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "Файл створено",
     "create_file_error": "Не вдалося створити файл",
     "favorites": "Вибране",
diff --git a/locales/zh/common.json b/locales/zh/common.json
index feb684df..cf4bf5ea 100644
--- a/locales/zh/common.json
+++ b/locales/zh/common.json
@@ -2921,6 +2921,10 @@
     "duplicate": "创建副本",
     "duplicate_success": "复制成功",
     "duplicate_error": "复制失败",
+    "share": "Share",
+    "shared": "Shared",
+    "shared_with_me": "Shared with me",
+    "shared_by": "Shared by {name}",
     "create_file_success": "文件已创建",
     "create_file_error": "创建文件失败",
     "favorites": "收藏夹",
diff --git a/stores/file-store.ts b/stores/file-store.ts
index 35bee40b..471c7824 100644
--- a/stores/file-store.ts
+++ b/stores/file-store.ts
@@ -1,6 +1,6 @@
 import { create } from 'zustand';
 import type { IJMAPClient } from '@/lib/jmap/client-interface';
-import type { FileNode } from '@/lib/jmap/types';
+import type { FileNode, FileNodeRights } from '@/lib/jmap/types';
 
 export interface FileResource {
   id: string;
@@ -12,6 +12,14 @@ export interface FileResource {
   lastModified: string;
   blobId: string | null;
   parentId: string | null;
+  // Sharing (RFC 9670). `shareWith` has entries when this node is shared out by
+  // the current user; `myRights` describes what the viewer may do; `isShared`
+  // marks nodes owned by another principal and surfaced under "Shared with me".
+  myRights?: FileNodeRights;
+  shareWith?: Record<string, FileNodeRights> | null;
+  isShared?: boolean;
+  ownerAccountId?: string;
+  ownerName?: string;
 }
 
 interface UploadProgress {
@@ -57,6 +65,8 @@ interface FileState {
   favorites: string[];
   recentFiles: { name: string; id: string; timestamp: number }[];
   lastAction: UndoAction | null;
+  /** Top-level FileNodes shared with the user by other principals ("Shared with me"). */
+  sharedRoots: FileResource[];
 
   // Actions
   initClient: (client: IJMAPClient, accountId?: string | null) => void;
@@ -103,6 +113,10 @@ interface FileState {
   toggleFavorite: (path: string) => void;
   addRecentFile: (name: string, id: string) => void;
   undoLastAction: () => Promise<void>;
+  /** Add, update (rights), or remove (rights=null) a principal's share on a node. */
+  shareResource: (id: string, principalId: string, rights: FileNodeRights | null) => Promise<void>;
+  /** Load the top-level nodes shared with the user by other principals. */
+  loadSharedRoots: () => Promise<void>;
 }
 
 const DIRECTORY_TYPES = new Set(['d', 'application/x-directory', 'text/directory', 'httpd/unix-directory', 'inode/directory']);
@@ -144,6 +158,13 @@ function childrenOf(nodes: FileNode[], parentId: string | null): FileNode[] {
   return nodes.filter(n => (n.parentId ?? null) === parentId);
 }
 
+// Nodes from a non-primary (shared) account are namespaced "accountId:nodeId"
+// by listAllFileNodesAcrossAccounts(). JMAP ids never contain ':', so the
+// separator unambiguously marks a node we're browsing inside a shared account.
+function isCrossAccountId(id: string | null): boolean {
+  return id != null && id.includes(':');
+}
+
 function nodeToResource(node: FileNode): FileResource {
   const isDir = isFolder(node);
   return {
@@ -156,6 +177,11 @@ function nodeToResource(node: FileNode): FileResource {
     lastModified: node.updated || node.created,
     blobId: node.blobId,
     parentId: node.parentId,
+    myRights: node.myRights,
+    shareWith: node.shareWith,
+    isShared: node.isShared,
+    ownerAccountId: node.accountId,
+    ownerName: node.accountName,
   };
 }
 
@@ -213,6 +239,7 @@ export const useFileStore = create<FileState>((set, get) => ({
   clipboard: null,
   uploadAbortController: null,
   lastAction: null,
+  sharedRoots: [],
   favorites: (() => {
     try { return JSON.parse(localStorage.getItem('files-favorites') || '[]'); } catch { return []; }
   })(),
@@ -480,8 +507,12 @@ export const useFileStore = create<FileState>((set, get) => ({
     try {
       // Fetch the whole tree once and select the current parent's direct
       // children locally. Hierarchy is derived from parentId links, exactly as
-      // the JMAP FileNode spec intends (issue #379).
-      const allNodes = await client.listAllFileNodes();
+      // the JMAP FileNode spec intends (issue #379). When browsing inside a
+      // folder shared by another principal (namespaced id), pull the tree
+      // across all accessible accounts so the shared subtree is visible.
+      const allNodes = isCrossAccountId(parentId)
+        ? await client.listAllFileNodesAcrossAccounts()
+        : await client.listAllFileNodes();
       const resources = sortResources(childrenOf(allNodes, parentId).map(nodeToResource));
 
       // Prune recent files whose backing node no longer exists on the server
@@ -982,4 +1013,35 @@ export const useFileStore = create<FileState>((set, get) => ({
     set({ lastAction: null });
     await refresh();
   },
+
+  shareResource: async (id: string, principalId: string, rights: FileNodeRights | null) => {
+    const { client, currentAccountId, refresh } = get();
+    if (!client) return;
+    // Owned nodes are browsed in the current account, so their ids are not
+    // namespaced; route the share to that account (defaults to the files account).
+    await client.setFileNodeShare(id, principalId, rights, currentAccountId ?? undefined);
+    await refresh();
+  },
+
+  loadSharedRoots: async () => {
+    const { client } = get();
+    if (!client) {
+      set({ sharedRoots: [] });
+      return;
+    }
+    try {
+      const all = await client.listAllFileNodesAcrossAccounts();
+      const idSet = new Set(all.map(n => n.id));
+      // A shared node is a "root" of the shared-with-me tree when its parent is
+      // not among the nodes the user can see (either null, or owned by a
+      // principal whose ancestor folders weren't shared).
+      const roots = all.filter(n =>
+        n.isShared && (n.parentId == null || !idSet.has(n.parentId)),
+      );
+      set({ sharedRoots: sortResources(roots.map(nodeToResource)) });
+    } catch (error) {
+      console.error('[Files] Failed to load shared roots:', error);
+      set({ sharedRoots: [] });
+    }
+  },
 }));