chore: update version number to 0.1.51

VERSION

@@ -1 +1 @@
-0.1.45
+0.1.51

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "bulwark-mobile",
-  "version": "0.1.45",
+  "version": "0.1.51",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "bulwark-mobile",
-      "version": "0.1.45",
+      "version": "0.1.51",
       "license": "AGPL-3.0-only",
       "dependencies": {
         "@react-native-async-storage/async-storage": "2.2.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "bulwark-mobile",
-  "version": "0.1.45",
+  "version": "0.1.51",
   "license": "AGPL-3.0-only",
   "main": "index.ts",
   "scripts": {

src/api/__tests__/calendar.test.ts

@@ -42,10 +42,10 @@ describe('calendar operations', () => {
   });
 
   describe('queryEvents', () => {
-    it('should send a CalendarEvent/query without server-side filter', async () => {
-      // Stalwart rejects inCalendars/after/before, so we fetch unfiltered and
-      // filter client-side. Asserting on the absence of `filter` keeps that
-      // contract pinned.
+    it('should filter via singular inCalendar conditions (Stalwart-compatible)', async () => {
+      // Stalwart rejects the draft's plural `inCalendars` filter (and
+      // after/before); calendars are restricted via singular `inCalendar`
+      // conditions and date filtering stays client-side.
       mockRequest.mockResolvedValue({
         methodResponses: [['CalendarEvent/query', { ids: ['ev1', 'ev2'] }, '0']],
       });
@@ -55,9 +55,35 @@ describe('calendar operations', () => {
 
       const call = mockRequest.mock.calls[0][0][0];
       expect(call[0]).toBe('CalendarEvent/query');
-      expect(call[1].filter).toBeUndefined();
+      expect(call[1].filter).toEqual({ inCalendar: 'cal-1' });
       expect(call[1].accountId).toBe('acc-1');
     });
+
+    it('should OR multiple calendars and respect the target account', async () => {
+      mockRequest.mockResolvedValue({
+        methodResponses: [['CalendarEvent/query', { ids: [] }, '0']],
+      });
+
+      await queryEvents(['cal-1', 'cal-2'], '', '', 'acc-shared');
+
+      const call = mockRequest.mock.calls[0][0][0];
+      expect(call[1].filter).toEqual({
+        operator: 'OR',
+        conditions: [{ inCalendar: 'cal-1' }, { inCalendar: 'cal-2' }],
+      });
+      expect(call[1].accountId).toBe('acc-shared');
+    });
+
+    it('should omit the filter when no calendars are given', async () => {
+      mockRequest.mockResolvedValue({
+        methodResponses: [['CalendarEvent/query', { ids: [] }, '0']],
+      });
+
+      await queryEvents([], '', '');
+
+      const call = mockRequest.mock.calls[0][0][0];
+      expect(call[1].filter).toBeUndefined();
+    });
   });
 
   describe('getEvents', () => {

src/api/__tests__/files.test.ts

@@ -0,0 +1,252 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+vi.mock('../jmap-client', () => ({
+  jmapClient: {
+    accountId: 'acc-1',
+    request: vi.fn(),
+    hasCapability: vi.fn(),
+    currentSession: null as unknown,
+  },
+}));
+
+vi.mock('../blob', () => ({
+  getDownloadUrl: vi.fn(
+    (blobId: string, _name?: string, _type?: string, accountId?: string) =>
+      `https://dl/${accountId ?? 'own'}/${blobId}`,
+  ),
+  uploadBlob: vi.fn(),
+  uploadBytes: vi.fn(),
+}));
+
+import { jmapClient } from '../jmap-client';
+import { CAPABILITIES } from '../types';
+import {
+  createFolder,
+  deleteFileNodes,
+  getAllFileNodesAcrossAccounts,
+  getFileNodeDownloadUrl,
+  getPrincipals,
+  isCrossAccountId,
+  isFolder,
+  setFileNodeShare,
+} from '../files';
+
+const mockRequest = jmapClient.request as ReturnType<typeof vi.fn>;
+const mockHasCapability = jmapClient.hasCapability as ReturnType<typeof vi.fn>;
+
+function setSession(session: unknown) {
+  (jmapClient as { currentSession: unknown }).currentSession = session;
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mockHasCapability.mockImplementation(
+    (urn: string) => urn === CAPABILITIES.FILES || urn === CAPABILITIES.PRINCIPALS,
+  );
+  setSession({
+    primaryAccounts: { [CAPABILITIES.FILES]: 'acc-1' },
+    accounts: {
+      'acc-1': { name: 'me@example.com', isPersonal: true },
+    },
+  });
+});
+
+describe('isFolder', () => {
+  it('treats blob-less nodes as folders and anything with a blob as a file', () => {
+    // #379: a blob-marked node — even the legacy type:'d' dir markers — is a
+    // 0-byte file that nothing can be parented under.
+    expect(isFolder({ blobId: null })).toBe(true);
+    expect(isFolder({ blobId: undefined })).toBe(true);
+    expect(isFolder({ blobId: 'blob-1' })).toBe(false);
+  });
+});
+
+describe('createFolder', () => {
+  it('creates a real container node: no blobId/type/size, parentId set', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/set', { created: { 'new-dir': { id: 'f1' } } }, '0']],
+    });
+
+    await createFolder('Docs', 'parent-1');
+
+    const [method, args] = mockRequest.mock.calls[0][0][0];
+    expect(method).toBe('FileNode/set');
+    expect(args.create['new-dir']).toEqual({ name: 'Docs', parentId: 'parent-1' });
+  });
+
+  it('omits parentId at the root', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/set', { created: { 'new-dir': { id: 'f1' } } }, '0']],
+    });
+
+    await createFolder('Docs', null);
+
+    const args = mockRequest.mock.calls[0][0][0][1];
+    expect(args.create['new-dir']).toEqual({ name: 'Docs' });
+  });
+});
+
+describe('deleteFileNodes', () => {
+  it('lets the server cascade into folder children', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/set', { destroyed: ['f1'] }, '0']],
+    });
+
+    await deleteFileNodes(['f1']);
+
+    const args = mockRequest.mock.calls[0][0][0][1];
+    expect(args.destroy).toEqual(['f1']);
+    expect(args.onDestroyRemoveChildren).toBe(true);
+  });
+
+  it('throws when the server refuses a destroy', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [
+        ['FileNode/set', { notDestroyed: { f1: { description: 'forbidden' } } }, '0'],
+      ],
+    });
+
+    await expect(deleteFileNodes(['f1'])).rejects.toThrow('forbidden');
+  });
+});
+
+describe('setFileNodeShare', () => {
+  it('patches shareWith/{principalId} and requests the principals:owner capability', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/set', { updated: { 'node-1': null } }, '0']],
+    });
+    const rights = {
+      mayRead: true, mayAddChildren: false, mayRename: false,
+      mayDelete: false, mayModifyContent: false, mayShare: false,
+    };
+
+    await setFileNodeShare('node-1', 'principal-2', rights);
+
+    const [calls, using] = mockRequest.mock.calls[0];
+    expect(calls[0][1].update['node-1']).toEqual({ 'shareWith/principal-2': rights });
+    expect(using).toContain(CAPABILITIES.PRINCIPALS_OWNER);
+  });
+
+  it('sends null rights to revoke access', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/set', { updated: { 'node-1': null } }, '0']],
+    });
+
+    await setFileNodeShare('node-1', 'principal-2', null);
+
+    const args = mockRequest.mock.calls[0][0][0][1];
+    expect(args.update['node-1']).toEqual({ 'shareWith/principal-2': null });
+  });
+
+  it('throws when the server rejects or does not confirm the update', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [
+        ['FileNode/set', { notUpdated: { 'node-1': { description: 'no mayShare right' } } }, '0'],
+      ],
+    });
+    await expect(setFileNodeShare('node-1', 'p2', null)).rejects.toThrow('no mayShare right');
+
+    mockRequest.mockResolvedValue({ methodResponses: [['FileNode/set', {}, '0']] });
+    await expect(setFileNodeShare('node-1', 'p2', null)).rejects.toThrow(
+      'Server did not confirm the share update',
+    );
+  });
+});
+
+describe('getAllFileNodesAcrossAccounts', () => {
+  it('namespaces ids of nodes from other principals and tags them isShared', async () => {
+    setSession({
+      primaryAccounts: { [CAPABILITIES.FILES]: 'acc-1' },
+      accounts: {
+        'acc-1': { name: 'me@example.com', isPersonal: true },
+        'acc-2': { name: 'Team', isPersonal: false },
+      },
+    });
+    mockRequest
+      .mockResolvedValueOnce({
+        methodResponses: [
+          ['FileNode/get', { list: [{ id: 'own-1', name: 'mine.txt', parentId: null, blobId: 'b1' }] }, '0'],
+        ],
+      })
+      .mockResolvedValueOnce({
+        methodResponses: [
+          ['FileNode/get', {
+            list: [
+              { id: 's1', name: 'Shared Folder', parentId: null, blobId: null },
+              { id: 's2', name: 'inside.txt', parentId: 's1', blobId: 'b2' },
+            ],
+          }, '0'],
+        ],
+      });
+
+    const nodes = await getAllFileNodesAcrossAccounts();
+
+    expect(nodes).toHaveLength(3);
+    const own = nodes.find((n) => n.id === 'own-1')!;
+    expect(own.isShared).toBe(false);
+    expect(isCrossAccountId(own.id)).toBe(false);
+
+    const folder = nodes.find((n) => n.name === 'Shared Folder')!;
+    expect(folder.id).toBe('acc-2:s1');
+    expect(folder.isShared).toBe(true);
+    expect(folder.accountId).toBe('acc-2');
+    expect(folder.accountName).toBe('Team');
+
+    // parentId is namespaced the same way so child lookups keep working.
+    const child = nodes.find((n) => n.name === 'inside.txt')!;
+    expect(child.parentId).toBe('acc-2:s1');
+  });
+
+  it('skips personal accounts without the filenode capability', async () => {
+    setSession({
+      primaryAccounts: { [CAPABILITIES.FILES]: 'acc-1' },
+      accounts: {
+        'acc-1': { name: 'me@example.com', isPersonal: true },
+        'acc-3': { name: 'other personal', isPersonal: true },
+      },
+    });
+    mockRequest.mockResolvedValue({
+      methodResponses: [['FileNode/get', { list: [] }, '0']],
+    });
+
+    await getAllFileNodesAcrossAccounts();
+
+    expect(mockRequest).toHaveBeenCalledTimes(1);
+    expect(mockRequest.mock.calls[0][0][0][1].accountId).toBe('acc-1');
+  });
+});
+
+describe('getFileNodeDownloadUrl', () => {
+  it('routes shared blobs to the owning account', () => {
+    const url = getFileNodeDownloadUrl({
+      id: 'acc-2:s2', name: 'inside.txt', type: 'text/plain',
+      blobId: 'b2', accountId: 'acc-2',
+    });
+    expect(url).toBe('https://dl/acc-2/b2');
+  });
+});
+
+describe('getPrincipals', () => {
+  it('queries then gets via back-reference', async () => {
+    mockRequest.mockResolvedValue({
+      methodResponses: [
+        ['Principal/query', { ids: ['p1'] }, '0'],
+        ['Principal/get', { list: [{ id: 'p1', name: 'other', type: 'individual' }] }, '1'],
+      ],
+    });
+
+    const principals = await getPrincipals();
+
+    expect(principals).toEqual([{ id: 'p1', name: 'other', type: 'individual' }]);
+    const calls = mockRequest.mock.calls[0][0];
+    expect(calls[0][0]).toBe('Principal/query');
+    expect(calls[1][0]).toBe('Principal/get');
+    expect(calls[1][1]['#ids']).toEqual({ resultOf: '0', name: 'Principal/query', path: '/ids' });
+  });
+
+  it('returns empty when the server lacks the principals capability', async () => {
+    mockHasCapability.mockReturnValue(false);
+    expect(await getPrincipals()).toEqual([]);
+    expect(mockRequest).not.toHaveBeenCalled();
+  });
+});

src/api/blob.ts

@@ -116,12 +116,15 @@ export function getDownloadUrl(
   blobId: string,
   name?: string,
   type?: string,
+  // Blobs of nodes shared by another principal live in the owner's account;
+  // downloading them with our own accountId 404s.
+  accountId?: string,
 ): string {
   const session = jmapClient.currentSession;
   if (!session) throw new Error('Not connected');
 
   return session.downloadUrl
-    .replace('{accountId}', encodeURIComponent(jmapClient.accountId))
+    .replace('{accountId}', encodeURIComponent(accountId ?? jmapClient.accountId))
     .replace('{blobId}', encodeURIComponent(blobId))
     .replace('{name}', encodeURIComponent(name ?? 'download'))
     .replace('{type}', encodeURIComponent(type ?? 'application/octet-stream'));

src/api/calendar.ts

@@ -4,6 +4,39 @@ import type { Calendar, CalendarEvent } from './types';
 
 const USING = [CAPABILITIES.CORE, CAPABILITIES.CALENDARS];
 
+/**
+ * IANA time zone of the device, sent as the `timeZone` argument on
+ * CalendarEvent/query and CalendarEvent/get. Stalwart interprets LocalDateTime
+ * filter values and computes utcStart/utcEnd for floating events in this zone,
+ * defaulting to UTC when absent — which shifts range boundaries and
+ * floating-event times for any user not in UTC. Stalwart ignores unparseable
+ * values, so sending it is always safe.
+ */
+function getUserTimeZone(): string | undefined {
+  try {
+    return Intl.DateTimeFormat().resolvedOptions().timeZone || undefined;
+  } catch {
+    return undefined;
+  }
+}
+
+/**
+ * Build a CalendarEvent/query filter restricting results to the given
+ * calendars. Stalwart implements the singular `inCalendar` condition (one
+ * calendar id per condition), not the draft's plural `inCalendars` array —
+ * sending the plural form fails the whole query with `unsupportedFilter`.
+ * Multiple calendars are expressed as an OR of singular conditions.
+ */
+function buildInCalendarFilter(calendarIds: string[]): Record<string, unknown> {
+  if (calendarIds.length === 1) {
+    return { inCalendar: calendarIds[0] };
+  }
+  return {
+    operator: 'OR',
+    conditions: calendarIds.map((id) => ({ inCalendar: id })),
+  };
+}
+
 const CALENDAR_EVENT_PROPERTIES = [
   'id', '@type', 'uid', 'calendarIds', 'title', 'description',
   'start', 'duration', 'timeZone', 'showWithoutTime',
@@ -26,43 +59,92 @@ function methodResult<T = any>(res: any, index = 0): T {
   return entry[1] as T;
 }
 
+// Other session accounts that expose the calendars capability hold calendars
+// shared with the user (JMAP surfaces shared data under the sharer's account).
+function sharedCalendarAccountIds(): string[] {
+  const session = jmapClient.currentSession;
+  const primary = jmapClient.accountId;
+  return Object.entries(session?.accounts ?? {})
+    .filter(([id, info]) =>
+      id !== primary && !!info.accountCapabilities?.[CAPABILITIES.CALENDARS])
+    .map(([id]) => id);
+}
+
 export async function getCalendars(): Promise<Calendar[]> {
   const accountId = jmapClient.accountId;
   const res = await jmapClient.request(
     [['Calendar/get', { accountId }, '0']],
     USING,
   );
-  return methodResult<{ list: Calendar[] }>(res).list ?? [];
+  const own = methodResult<{ list: Calendar[] }>(res).list ?? [];
+
+  // Calendars shared with the user live in other session accounts. Failures
+  // there (revoked share, transient error) must not hide the user's own
+  // calendars, so each shared account is fetched best-effort.
+  const shared = await Promise.all(
+    sharedCalendarAccountIds().map(async (sharedAccountId) => {
+      try {
+        const sharedRes = await jmapClient.request(
+          [['Calendar/get', { accountId: sharedAccountId }, '0']],
+          USING,
+        );
+        const list = methodResult<{ list: Calendar[] }>(sharedRes).list ?? [];
+        // JMAP calendar ids are only unique within an account, so a shared
+        // "default" calendar collides with the user's own "default". Namespace
+        // the id (keeping the real id in originalId) so visibility toggles,
+        // event-query routing, and create/default mutations don't cross wires.
+        // Mirrors webmail's getAllCalendars.
+        return list.map((cal) => ({
+          ...cal,
+          id: `${sharedAccountId}:${cal.id}`,
+          originalId: cal.id,
+          accountId: sharedAccountId,
+          isShared: true,
+        }));
+      } catch {
+        return [];
+      }
+    }),
+  );
+  return [...own, ...shared.flat()];
 }
 
 export async function queryEvents(
-  _calendarIds: string[],
+  calendarIds: string[],
   _after: string,
   _before: string,
+  accountId?: string,
 ): Promise<string[]> {
-  // Stalwart rejects inCalendars/after/before filters on CalendarEvent/query.
-  // Fetch all events in the account; calendar visibility + date filtering is
-  // done client-side.
-  const accountId = jmapClient.accountId;
+  // Stalwart rejects after/before filters on CalendarEvent/query; date
+  // filtering is done client-side. Calendars are restricted via the singular
+  // `inCalendar` condition (the plural `inCalendars` fails the whole query
+  // with unsupportedFilter on Stalwart).
+  const account = accountId || jmapClient.accountId;
+  const args: Record<string, unknown> = { accountId: account, limit: 1000 };
+  const timeZone = getUserTimeZone();
+  if (timeZone) args.timeZone = timeZone;
+  if (calendarIds.length > 0) args.filter = buildInCalendarFilter(calendarIds);
   const res = await jmapClient.request(
-    [['CalendarEvent/query', { accountId, limit: 1000 }, '0']],
+    [['CalendarEvent/query', args, '0']],
     USING,
   );
   return methodResult<{ ids: string[] }>(res).ids ?? [];
 }
 
-export async function getEvents(ids: string[]): Promise<CalendarEvent[]> {
+export async function getEvents(ids: string[], accountId?: string): Promise<CalendarEvent[]> {
   if (ids.length === 0) return [];
-  const accountId = jmapClient.accountId;
+  const account = accountId || jmapClient.accountId;
+  const timeZone = getUserTimeZone();
   const batchSize = jmapClient.getMaxObjectsInGet();
   const all: CalendarEvent[] = [];
   for (let i = 0; i < ids.length; i += batchSize) {
     const batch = ids.slice(i, i + batchSize);
     const res = await jmapClient.request(
       [['CalendarEvent/get', {
-        accountId,
+        accountId: account,
         ids: batch,
         properties: CALENDAR_EVENT_PROPERTIES,
+        ...(timeZone ? { timeZone } : {}),
       }, '0']],
       USING,
     );
@@ -91,8 +173,9 @@ export async function createEvent(
   event: Partial<CalendarEvent>,
   calendarId: string,
   sendSchedulingMessages?: boolean,
+  targetAccountId?: string,
 ): Promise<CalendarEvent> {
-  const accountId = jmapClient.accountId;
+  const accountId = targetAccountId || jmapClient.accountId;
   const res = await jmapClient.request(
     [['CalendarEvent/set', setArgs(accountId, {
       create: {
@@ -117,9 +200,10 @@ export async function createEvent(
 export async function batchCreateEvents(
   events: Partial<CalendarEvent>[],
   calendarId: string,
+  targetAccountId?: string,
 ): Promise<number> {
   if (events.length === 0) return 0;
-  const accountId = jmapClient.accountId;
+  const accountId = targetAccountId || jmapClient.accountId;
   const create: Record<string, Partial<CalendarEvent>> = {};
   events.forEach((e, i) => {
     create[`evt-${i}`] = { ...e, calendarIds: { [calendarId]: true } };
@@ -136,8 +220,9 @@ export async function updateEvent(
   id: string,
   changes: Partial<CalendarEvent> | Record<string, unknown>,
   sendSchedulingMessages?: boolean,
+  targetAccountId?: string,
 ): Promise<void> {
-  const accountId = jmapClient.accountId;
+  const accountId = targetAccountId || jmapClient.accountId;
   const res = await jmapClient.request(
     [['CalendarEvent/set', setArgs(accountId, { update: { [id]: changes } }, sendSchedulingMessages), '0']],
     USING,
@@ -150,8 +235,9 @@ export async function updateEvent(
 export async function deleteEvents(
   ids: string[],
   sendSchedulingMessages?: boolean,
+  targetAccountId?: string,
 ): Promise<void> {
-  const accountId = jmapClient.accountId;
+  const accountId = targetAccountId || jmapClient.accountId;
   await jmapClient.request(
     [['CalendarEvent/set', setArgs(accountId, { destroy: ids }, sendSchedulingMessages), '0']],
     USING,
@@ -165,8 +251,9 @@ export async function rsvpEvent(
   participantId: string,
   status: 'accepted' | 'declined' | 'tentative',
   replyTo?: Record<string, string> | null,
+  targetAccountId?: string,
 ): Promise<void> {
-  const accountId = jmapClient.accountId;
+  const accountId = targetAccountId || jmapClient.accountId;
   // Escape per RFC 6901: ~ → ~0, / → ~1.
   const escaped = participantId.replace(/~/g, '~0').replace(/\//g, '~1');
   const patch: Record<string, unknown> = {
@@ -225,6 +312,23 @@ export async function createCalendar(
   return created;
 }
 
+/**
+ * Mark a calendar as the account default. `isDefault` is read-only in
+ * Stalwart's Calendar/set — the default is changed via the
+ * `onSuccessSetIsDefault` request argument instead.
+ */
+export async function setDefaultCalendar(
+  calendarId: string,
+  targetAccountId?: string,
+): Promise<void> {
+  const accountId = targetAccountId || jmapClient.accountId;
+  const res = await jmapClient.request(
+    [['Calendar/set', { accountId, onSuccessSetIsDefault: calendarId }, '0']],
+    USING,
+  );
+  methodResult(res);
+}
+
 // Destroy a calendar. `onDestroyEvents: 'destroy'` removes its events too —
 // Stalwart otherwise refuses to delete a non-empty calendar.
 export async function deleteCalendar(id: string): Promise<void> {

src/api/files.ts

@@ -1,188 +1,277 @@
 import { jmapClient } from './jmap-client';
 import { CAPABILITIES } from './types';
-import type { FileNode } from './types';
-import { getDownloadUrl, uploadBlob, uploadBytes } from './blob';
+import type { FileNode, FileNodeRights, Principal } from './types';
+import { getDownloadUrl, uploadBlob } from './blob';
 
-const USING = [CAPABILITIES.CORE, CAPABILITIES.FILES];
-
-// Stalwart and other JMAP servers use one of these strings on FileNode.type to
-// mark a directory; everything else is a MIME type.
-const DIRECTORY_TYPES = new Set([
-  'd',
-  'application/x-directory',
-  'text/directory',
-  'httpd/unix-directory',
-  'inode/directory',
-]);
-
-export function isDirectory(node: Pick<FileNode, 'type'>): boolean {
-  const t = node.type;
-  if (!t) return false;
-  return DIRECTORY_TYPES.has(t) || t.includes('directory');
+// A FileNode is a folder (container) only when it has no blob content — the
+// server stores it with `file == null`. Sending a blobId/type/size on create
+// (as older builds did: type 'd' + an empty blob) makes a 0-byte FILE that
+// nothing can ever be parented under (#379). The webmail migrates those
+// legacy flat-named nodes into the real parentId hierarchy on load; this app
+// reads and writes only the real hierarchy.
+export function isFolder(node: Pick<FileNode, 'blobId'>): boolean {
+  return node.blobId == null;
 }
 
-// Stalwart rejects `/` in FileNode names, so the webmail (and now this app)
-// uses U+2215 DIVISION SLASH as the path separator inside the flat `name`
-// field. Hierarchy is encoded into the name — there is no `parentId` nesting.
-// e.g. a file inside the `Documents` folder is stored with
-// `name = "Documents∕report.pdf"`. The display name shown to the user
-// strips the prefix.
-export const PATH_SEP = '∕';
+// Stalwart omits shareWith/myRights from FileNode/get unless they are
+// requested explicitly, so the share sheet and indicators must name them here.
+const FILE_NODE_PROPERTIES = [
+  'id', 'parentId', 'name', 'type', 'blobId', 'size', 'created', 'updated',
+  'shareWith', 'myRights',
+];
 
-// Path is a list of folder display names from root. [] is root,
-// ['Documents'] is inside Documents, ['Documents','sub'] is inside the
-// `sub` folder under Documents.
-export function pathToPrefix(path: readonly string[]): string {
-  if (path.length === 0) return '';
-  return path.join(PATH_SEP) + PATH_SEP;
+export function supportsSharing(): boolean {
+  return jmapClient.hasCapability(CAPABILITIES.PRINCIPALS);
 }
 
-// True when `node` is a direct child (not a descendant) of `prefix`.
-export function isDirectChildOfPrefix(node: Pick<FileNode, 'name'>, prefix: string): boolean {
-  if (!node.name) return false;
-  if (prefix === '') return !node.name.includes(PATH_SEP);
-  if (!node.name.startsWith(prefix)) return false;
-  const rest = node.name.slice(prefix.length);
-  return rest.length > 0 && !rest.includes(PATH_SEP);
+function filesAccountId(): string {
+  return (
+    jmapClient.currentSession?.primaryAccounts?.[CAPABILITIES.FILES] ??
+    jmapClient.accountId
+  );
 }
 
-export function nodeDisplayName(node: Pick<FileNode, 'name'>, prefix: string): string {
-  return prefix && node.name.startsWith(prefix) ? node.name.slice(prefix.length) : node.name;
+function fileUsing(): string[] {
+  const using: string[] = [CAPABILITIES.CORE];
+  if (jmapClient.hasCapability(CAPABILITIES.FILES)) {
+    using.push(CAPABILITIES.FILES);
+  }
+  // Required for shareWith/myRights on FileNode and for cross-account
+  // (shared-with-me) FileNode/get.
+  if (supportsSharing()) {
+    using.push(CAPABILITIES.PRINCIPALS_OWNER);
+  }
+  return using;
 }
 
-// Stalwart's FileNode/get does not support a parentId filter and some builds
-// omit `type` from the default property set. We fetch the whole tree and
-// filter client-side; properties are listed explicitly so `isDirectory()`
-// always has a value to look at.
-const FILE_NODE_PROPERTIES = ['id', 'parentId', 'name', 'type', 'blobId', 'size', 'created', 'updated'];
+// Nodes fetched from another principal's account are namespaced
+// "accountId:nodeId" so they can't collide with the primary account's ids.
+// JMAP ids never contain ':', so the separator unambiguously marks a shared
+// (cross-account) node.
+export function isCrossAccountId(id: string | null | undefined): boolean {
+  return id != null && id.includes(':');
+}
 
+// Fetch every FileNode in the account, files AND folders, to build the
+// hierarchy client-side from parentId links.
+//
+// IMPORTANT: this uses FileNode/get with ids:null (return-all), NOT
+// FileNode/query — Stalwart's query only returns leaf files and omits folder
+// nodes entirely, which would make every folder invisible.
 export async function getAllFileNodes(): Promise<FileNode[]> {
-  const accountId = jmapClient.accountId;
+  const accountId = filesAccountId();
   const res = await jmapClient.request(
     [['FileNode/get', { accountId, ids: null, properties: FILE_NODE_PROPERTIES }, '0']],
-    USING,
+    fileUsing(),
   );
-  return (res.methodResponses[0][1].list ?? []) as FileNode[];
+  const result = res.methodResponses[0];
+  if (!result || result[0] === 'error') {
+    throw new Error(result?.[1]?.description || 'FileNode list failed');
+  }
+  return (result[1].list ?? []) as FileNode[];
 }
 
-export async function createFileNode(
-  fileNode: Partial<FileNode>,
-): Promise<FileNode> {
-  const accountId = jmapClient.accountId;
-  const res = await jmapClient.request(
-    [['FileNode/set', {
-      accountId,
-      create: { 'new-file': fileNode },
-    }, '0']],
-    USING,
-  );
-  const created = res.methodResponses[0][1].created?.['new-file'];
-  if (!created) {
-    const err = res.methodResponses[0][1].notCreated?.['new-file'];
-    throw new Error(err?.description || 'Create failed');
+// Accounts (primary + shared/group) that can hold FileNodes: any non-primary
+// account that advertises the filenode capability or is non-personal, since
+// Stalwart doesn't always advertise capabilities on shared accounts.
+function filesCapableAccountIds(): string[] {
+  const primaryId = filesAccountId();
+  const accounts = jmapClient.currentSession?.accounts ?? {};
+  const rest = Object.entries(accounts)
+    .filter(([id, info]) =>
+      id !== primaryId &&
+      (info.accountCapabilities?.[CAPABILITIES.FILES] != null || !info.isPersonal))
+    .map(([id]) => id);
+  return [primaryId, ...rest];
+}
+
+// Fetch every FileNode the logged-in user can see across all accessible
+// accounts. Nodes owned by another principal (shared with the user) are
+// tagged `isShared: true` with the owning accountId/accountName, and their
+// ids/parentIds are namespaced "accountId:nodeId". Mirrors the webmail's
+// listAllFileNodesAcrossAccounts.
+export async function getAllFileNodesAcrossAccounts(): Promise<FileNode[]> {
+  const primaryId = filesAccountId();
+  const accounts = jmapClient.currentSession?.accounts ?? {};
+  const all: FileNode[] = [];
+
+  for (const accountId of filesCapableAccountIds()) {
+    const isPrimary = accountId === primaryId;
+    try {
+      const res = await jmapClient.request(
+        [['FileNode/get', { accountId, ids: null, properties: FILE_NODE_PROPERTIES }, '0']],
+        fileUsing(),
+      );
+      const result = res.methodResponses[0];
+      if (!result || result[0] === 'error') continue;
+      for (const node of (result[1].list ?? []) as FileNode[]) {
+        all.push({
+          ...node,
+          id: isPrimary ? node.id : `${accountId}:${node.id}`,
+          parentId: node.parentId == null
+            ? null
+            : (isPrimary ? node.parentId : `${accountId}:${node.parentId}`),
+          accountId,
+          accountName: accounts[accountId]?.name || accountId,
+          isShared: !isPrimary,
+        });
+      }
+    } catch {
+      // A single unreachable shared account shouldn't hide the user's own
+      // files; skip it and keep aggregating.
+    }
   }
-  return created;
+
+  return all;
 }
 
 export async function createFolder(
-  displayName: string,
-  currentPath: readonly string[],
+  name: string,
+  parentId: string | null,
 ): Promise<FileNode> {
-  // Stalwart's FileNode/set rejects directory creates without a blobId
-  // ("Missing blob id"), so we upload an empty blob first and reference it.
-  // Mirrors the webmail's createFileDirectory.
-  const blob = await uploadBytes(new Uint8Array(0), 'application/x-directory');
-  const fullName = pathToPrefix(currentPath) + displayName;
-  return createFileNode({ name: fullName, type: 'd', blobId: blob.blobId, size: 0 });
+  const accountId = filesAccountId();
+  const props: Record<string, unknown> = { name };
+  if (parentId !== null) props.parentId = parentId;
+
+  const res = await jmapClient.request(
+    [['FileNode/set', { accountId, create: { 'new-dir': props } }, '0']],
+    fileUsing(),
+  );
+  const result = res.methodResponses[0][1];
+  const created = result.created?.['new-dir'];
+  if (!created) {
+    const err = result.notCreated?.['new-dir'];
+    throw new Error(err?.description || 'Create folder failed');
+  }
+  return { ...props, ...created } as FileNode;
 }
 
 export async function updateFileNode(
   id: string,
   updates: Partial<Pick<FileNode, 'name' | 'parentId'>>,
 ): Promise<void> {
-  const accountId = jmapClient.accountId;
+  const accountId = filesAccountId();
   const res = await jmapClient.request(
     [['FileNode/set', { accountId, update: { [id]: updates } }, '0']],
-    USING,
+    fileUsing(),
   );
   const notUpdated = res.methodResponses[0][1].notUpdated?.[id];
   if (notUpdated) throw new Error(notUpdated.description || 'Update failed');
 }
 
-// Rename a node and, if it's a folder, cascade the rename to every descendant
-// so the encoded path stays consistent. The webmail does this same dance.
-export async function renameFileNode(
-  node: FileNode,
-  newDisplayName: string,
-  currentPath: readonly string[],
-  allNodes: readonly FileNode[],
-): Promise<void> {
-  const prefix = pathToPrefix(currentPath);
-  const oldServerName = node.name;
-  const newServerName = prefix + newDisplayName;
-  if (oldServerName === newServerName) return;
-
-  await updateFileNode(node.id, { name: newServerName });
-
-  if (isDirectory(node)) {
-    const oldFolderPrefix = oldServerName + PATH_SEP;
-    const newFolderPrefix = newServerName + PATH_SEP;
-    for (const n of allNodes) {
-      if (n.id === node.id) continue;
-      if (n.name.startsWith(oldFolderPrefix)) {
-        await updateFileNode(n.id, { name: newFolderPrefix + n.name.slice(oldFolderPrefix.length) });
-      }
-    }
-  }
+export async function renameFileNode(id: string, newName: string): Promise<void> {
+  await updateFileNode(id, { name: newName });
 }
 
 export async function deleteFileNodes(ids: string[]): Promise<void> {
   if (ids.length === 0) return;
-  const accountId = jmapClient.accountId;
-  await jmapClient.request(
-    [['FileNode/set', { accountId, destroy: ids }, '0']],
-    USING,
+  const accountId = filesAccountId();
+  const res = await jmapClient.request(
+    [['FileNode/set', {
+      accountId,
+      destroy: ids,
+      // The server removes descendant nodes of destroyed folders.
+      onDestroyRemoveChildren: true,
+    }, '0']],
+    fileUsing(),
   );
-}
-
-// Delete `targets` and every descendant. Stalwart doesn't enforce parent
-// references, so we collect descendants by name-prefix and destroy them all
-// in one call. Without this, deleting a folder leaves its files orphaned and
-// still discoverable at the old encoded path.
-export async function deleteWithDescendants(
-  targets: readonly FileNode[],
-  allNodes: readonly FileNode[],
-): Promise<void> {
-  const ids = new Set<string>();
-  for (const node of targets) {
-    ids.add(node.id);
-    if (isDirectory(node)) {
-      const folderPrefix = node.name + PATH_SEP;
-      for (const n of allNodes) {
-        if (n.name.startsWith(folderPrefix)) ids.add(n.id);
-      }
-    }
+  const notDestroyed = res.methodResponses[0][1].notDestroyed as
+    | Record<string, { description?: string }>
+    | undefined;
+  const failedIds = Object.keys(notDestroyed ?? {});
+  if (failedIds.length > 0) {
+    throw new Error(
+      notDestroyed![failedIds[0]]?.description || `Failed to delete ${failedIds.length} item(s)`,
+    );
   }
-  await deleteFileNodes(Array.from(ids));
 }
 
 export function getFileNodeDownloadUrl(node: FileNode): string {
   if (!node.blobId) throw new Error('Folders cannot be downloaded');
-  return getDownloadUrl(node.blobId, node.name, node.type);
+  return getDownloadUrl(node.blobId, node.name, node.type, node.accountId);
 }
 
 export async function uploadFileNode(
   uri: string,
-  displayName: string,
+  name: string,
   mimeType: string,
-  currentPath: readonly string[],
+  parentId: string | null,
 ): Promise<FileNode> {
+  const accountId = filesAccountId();
   const blob = await uploadBlob(uri, mimeType);
-  const fullName = pathToPrefix(currentPath) + displayName;
-  return createFileNode({
-    name: fullName,
-    type: blob.type || mimeType || 'application/octet-stream',
+  const type = blob.type || mimeType || 'application/octet-stream';
+  const props: Record<string, unknown> = {
+    name,
+    // Stalwart caps the stored MIME type; very long types fail the create.
+    type: type.length > 30 ? 'application/octet-stream' : type,
     blobId: blob.blobId,
     size: blob.size,
-  });
+  };
+  if (parentId !== null) props.parentId = parentId;
+
+  const res = await jmapClient.request(
+    [['FileNode/set', { accountId, create: { 'new-file': props } }, '0']],
+    fileUsing(),
+  );
+  const result = res.methodResponses[0][1];
+  const created = result.created?.['new-file'];
+  if (!created) {
+    const err = result.notCreated?.['new-file'];
+    throw new Error(err?.description || 'Upload failed');
+  }
+  return { ...props, ...created } as FileNode;
+}
+
+// ── Sharing (RFC 9670) ────────────────────────────────────
+
+// Add, update, or remove a principal's rights on an owned FileNode (file or
+// folder). Pass rights: null to revoke. Stalwart applies it via a
+// `shareWith/{principalId}` patch on FileNode/set. Sharing a folder shares
+// its whole subtree — which is why this app must store real parentId
+// hierarchy rather than the legacy flat-name encoding.
+export async function setFileNodeShare(
+  fileNodeId: string,
+  principalId: string,
+  rights: FileNodeRights | null,
+): Promise<void> {
+  const accountId = filesAccountId();
+  const res = await jmapClient.request(
+    [['FileNode/set', {
+      accountId,
+      update: { [fileNodeId]: { [`shareWith/${principalId}`]: rights } },
+    }, '0']],
+    fileUsing(),
+  );
+  const result = res.methodResponses[0][1];
+  if (result.notUpdated?.[fileNodeId]) {
+    throw new Error(result.notUpdated[fileNodeId].description || 'Failed to update file share');
+  }
+  if (!result.updated || !(fileNodeId in result.updated)) {
+    throw new Error('Server did not confirm the share update');
+  }
+}
+
+// List all principals visible to the user. Stalwart returns the full
+// directory regardless of `filter`, so callers filter client-side.
+export async function getPrincipals(): Promise<Principal[]> {
+  if (!supportsSharing()) return [];
+  const accountId = jmapClient.accountId;
+  const res = await jmapClient.request(
+    [
+      ['Principal/query', { accountId }, '0'],
+      ['Principal/get', {
+        accountId,
+        '#ids': { resultOf: '0', name: 'Principal/query', path: '/ids' },
+      }, '1'],
+    ],
+    [CAPABILITIES.CORE, CAPABILITIES.PRINCIPALS],
+  );
+  const getResp = res.methodResponses.find((r) => r[0] === 'Principal/get');
+  return (getResp?.[1].list ?? []) as Principal[];
+}
+
+// The principal id that represents the logged-in user (excluded from the
+// share picker — sharing with yourself is a no-op the server may reject).
+export function ownPrincipalId(): string {
+  return filesAccountId();
 }

src/api/types.ts

@@ -405,6 +405,7 @@ export interface VirtualLocation {
 }
 
 export interface RecurrenceRule {
+  '@type'?: 'RecurrenceRule';
   frequency: string;
   interval?: number;
   until?: string;
@@ -419,6 +420,8 @@ export interface RecurrenceRule {
   bySecond?: number[];
   bySetPosition?: number[];
   firstDayOfWeek?: string;
+  rscale?: string;
+  skip?: string;
 }
 
 export interface Alert {
@@ -452,6 +455,9 @@ export interface CalendarEvent {
   excludedRecurrenceRules?: RecurrenceRule[];
   recurrenceId?: string;
   originalId?: string;
+  // Client-only: the event's server-side calendarIds (raw, unprefixed), kept
+  // when `calendarIds` is remapped to namespaced store ids for shared events.
+  originalCalendarIds?: Record<string, boolean>;
   useDefaultAlerts?: boolean;
   alerts?: Record<string, Alert>;
   locations?: Record<string, EventLocation>;
@@ -467,6 +473,12 @@ export interface CalendarEvent {
   color?: string;
   // Client-only: account the event/occurrence belongs to (for shared/virtual).
   localAccountId?: string;
+  // Client-only: JMAP account the event was fetched from. Absent for the
+  // primary account; set for events on calendars shared with the user so
+  // mutations can be routed to the owning account.
+  accountId?: string;
+  // Client-only: true when the event lives on a calendar shared with the user.
+  isShared?: boolean;
 }
 
 export interface CalendarRights {
@@ -492,6 +504,21 @@ export interface Calendar {
   isDefault?: boolean;
   sortOrder?: number;
   myRights?: CalendarRights;
+  // Client-only: JMAP account the calendar was fetched from. Absent for the
+  // primary account; set for calendars shared with the user.
+  accountId?: string;
+  // Client-only: the real JMAP id of a shared calendar, before its `id` was
+  // namespaced as `${accountId}:${id}` to stay unique in the store. Mutations
+  // and event queries must use this raw id against the owning account.
+  originalId?: string;
+  // Client-only: true when the calendar lives in another account (shared
+  // with the user by its owner).
+  isShared?: boolean;
+  // Client-only: set when `color` has been replaced by the viewer's local
+  // override for a shared calendar (see lib/calendar-utils). When true, the
+  // override wins over per-event colors so the whole shared calendar paints
+  // uniformly.
+  colorIsLocalOverride?: boolean;
 }
 
 // ─── Files (FileNode) ───────────────────────────────────
@@ -505,6 +532,40 @@ export interface FileNode {
   size?: number;
   created?: string;
   updated?: string;
+  // JMAP Sharing (RFC 9670). Populated only when the server advertises the
+  // principals capability and the properties are requested explicitly. 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 ("Shared with me").
+  isShared?: boolean;
+  // Owning account's JMAP id and display name, set when aggregating nodes
+  // across accounts so blob downloads route to the right account.
+  accountId?: string;
+  accountName?: 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;
+}
+
+// RFC 9670 principal — an entity (user, group, resource) that files and
+// calendars can be shared with. On Stalwart the principal id doubles as the
+// account id of that user/group.
+export interface Principal {
+  id: string;
+  type: 'individual' | 'group' | 'resource' | 'location' | 'other';
+  name: string;
+  description?: string | null;
+  email?: string | null;
 }
 
 // ─── Push / SSE ─────────────────────────────────────────
@@ -538,4 +599,6 @@ export const CAPABILITIES = {
   SIEVE: 'urn:ietf:params:jmap:sieve',
   QUOTA: 'urn:ietf:params:jmap:quota',
   FILES: 'urn:ietf:params:jmap:filenode',
+  PRINCIPALS: 'urn:ietf:params:jmap:principals',
+  PRINCIPALS_OWNER: 'urn:ietf:params:jmap:principals:owner',
 } as const;

src/components/EmailBodyView.tsx

@@ -27,6 +27,15 @@ function arrayBufferToBase64(buffer: ArrayBuffer): string {
 interface EmailBodyViewProps {
   email: Email;
   senderEmail?: string;
+  // The body is a native WebView, which on Android swallows horizontal touches
+  // before the surrounding pager can see them. We detect a clear horizontal
+  // swipe inside the page and report it here so the pager can change messages.
+  onSwipe?: (direction: 'prev' | 'next') => void;
+  // Pinch-zoom state from inside the page: `pinching` while two fingers are
+  // down, `zoomed` while the content is scaled in. The hosts use it to freeze
+  // the surrounding vertical scroll / horizontal pager so a zoom gesture can't
+  // scroll the pane away or switch mails.
+  onZoomChange?: (zoom: { pinching: boolean; zoomed: boolean }) => void;
 }
 
 function extractHtmlBody(email: Email): string | null {
@@ -177,6 +186,30 @@ const HEIGHT_REPORTER = `
     var padR = parseFloat(cs.paddingRight) || 0;
     return b.clientWidth - padL - padR;
   }
+  // Shared zoom state, mutated by the pinch-zoom handler injected after this
+  // script. "fit" is the shrink-to-fit scale, "scale" the user's pinch factor
+  // on top of it, "tx" pans the zoomed overflow into view horizontally.
+  // Vertical panning needs no state here: the height reports below carry the
+  // scaled height, so the surrounding native ScrollView grows and scrolls.
+  var Z = window.__rnZoom = window.__rnZoom || {
+    scale: 1, tx: 0, pinching: false, fit: 1, layoutW: 0, avail: 0,
+  };
+  // Apply the combined fit × pinch transform using the cached layout numbers
+  // (cheap — no reflow), clamping the pan so content edges pin to the viewport.
+  function applyTransform(w) {
+    var s = Z.fit * Z.scale;
+    if (Z.scale > 1.001 || Z.fit < 0.999) {
+      var minTx = Math.min(0, Z.avail - Z.layoutW * s);
+      if (Z.tx < minTx) Z.tx = minTx;
+      if (Z.tx > 0) Z.tx = 0;
+      w.style.width = Z.layoutW + 'px';
+      w.style.transform = 'translateX(' + Z.tx + 'px) scale(' + s + ')';
+    } else {
+      Z.tx = 0;
+      w.style.width = '100%';
+      w.style.transform = 'none';
+    }
+  }
   // Shrink-to-fit: emails authored at a fixed width (e.g. 600px tables) overflow
   // a phone viewport and force horizontal scrolling. Lay the content out at its
   // natural width, then scale the whole block down so its widest element fits
@@ -189,18 +222,18 @@ const HEIGHT_REPORTER = `
     // (the widest unbreakable element) rather than a previously-scaled box.
     w.style.width = '100%';
     var content = w.scrollWidth;
-    if (content > avail + 1) {
-      var scale = avail / content;
-      w.style.width = content + 'px';
-      w.style.transform = 'scale(' + scale + ')';
-    } else {
-      w.style.transform = 'none';
-    }
+    Z.avail = avail;
+    Z.layoutW = content > avail + 1 ? content : avail;
+    Z.fit = avail / Z.layoutW;
+    applyTransform(w);
   }
   function measure() {
     var w = ensureWrapper();
     if (!w) return 0;
-    fitToWidth(w);
+    // While a pinch is in flight only re-apply the transform — a full re-fit
+    // resets the wrapper width and would thrash layout on every frame.
+    if (Z.pinching) applyTransform(w);
+    else fitToWidth(w);
     // getBoundingClientRect reflects the applied transform, so r.height is the
     // already-scaled visual height of the content.
     var r = w.getBoundingClientRect();
@@ -270,11 +303,161 @@ const HEIGHT_REPORTER = `
       img.addEventListener('error', report);
     });
   } catch (e) {}
+  // Hooks for the pinch-zoom handler script.
+  window.__rnApplyZoom = function () { var w = ensureWrapper(); if (w) applyTransform(w); };
+  window.__rnReport = report;
   true;
 })();
 `;
 
-export default function EmailBodyView({ email, senderEmail }: EmailBodyViewProps) {
+// Detect a clear horizontal flick inside the WebView and report it. Uses
+// capture-phase, passive listeners so it never blocks vertical scrolling, text
+// selection, or link taps — it only reacts to a quick, horizontal-dominant
+// gesture on release. Guarded so re-injection (onLoadEnd) is a no-op.
+const SWIPE_DETECTOR = `
+(function () {
+  if (window.__rnSwipeInit) return;
+  window.__rnSwipeInit = true;
+  var x0 = 0, y0 = 0, t0 = 0, tracking = false;
+  document.addEventListener('touchstart', function (e) {
+    if (e.touches.length !== 1) { tracking = false; return; }
+    var t = e.touches[0];
+    x0 = t.clientX; y0 = t.clientY; t0 = Date.now(); tracking = true;
+  }, { passive: true, capture: true });
+  document.addEventListener('touchend', function (e) {
+    if (!tracking) return;
+    tracking = false;
+    // While the content is pinch-zoomed, horizontal flicks pan the zoomed
+    // content — never switch mails.
+    if (window.__rnZoom && (window.__rnZoom.pinching || window.__rnZoom.scale > 1.001)) return;
+    var t = e.changedTouches[0];
+    if (!t) return;
+    var dx = t.clientX - x0, dy = t.clientY - y0, dt = Date.now() - t0;
+    if (dt < 700 && Math.abs(dx) > 55 && Math.abs(dx) > Math.abs(dy) * 1.8) {
+      if (window.ReactNativeWebView) {
+        window.ReactNativeWebView.postMessage(JSON.stringify({ type: 'swipe', dir: dx < 0 ? 'next' : 'prev' }));
+      }
+    }
+  }, { passive: true, capture: true });
+  true;
+})();
+`;
+
+// Pinch zoom + pan for the email content, driven entirely in the page: native
+// WebView zoom can't work here because the WebView is auto-height inside a
+// native ScrollView (viewport meta pins it to scale 1). A two-finger pinch
+// scales the measured wrapper (on top of the shrink-to-fit scale the height
+// reporter maintains) anchored at the fingers' horizontal midpoint; while
+// zoomed, one-finger horizontal drags pan via translateX and vertical drags
+// still scroll the surrounding ScrollView, which sees the scaled height
+// through the regular height reports. Pinch moves call preventDefault so the
+// engine consumes the gesture and Android parents don't intercept it; `zoom`
+// messages let the RN side freeze the pane scroll / pager as a second guard.
+const PINCH_ZOOM = `
+(function () {
+  if (window.__rnPinchInit) return;
+  window.__rnPinchInit = true;
+  var Z = window.__rnZoom = window.__rnZoom || {
+    scale: 1, tx: 0, pinching: false, fit: 1, layoutW: 0, avail: 0,
+  };
+  var MAX_ZOOM = 4;
+  var pinch = null; // { d0, s0, cx0, tx0 }
+  var pan = null;   // { x0, tx0 }
+  var rafPending = false;
+
+  function post(msg) {
+    if (window.ReactNativeWebView) {
+      window.ReactNativeWebView.postMessage(JSON.stringify(msg));
+    }
+  }
+  function apply() {
+    if (window.__rnApplyZoom) window.__rnApplyZoom();
+  }
+  // Height reports are rAF-throttled during the gesture so the RN container
+  // keeps up with the growing content without re-measuring on every move.
+  function scheduleReport() {
+    if (rafPending) return;
+    rafPending = true;
+    requestAnimationFrame(function () {
+      rafPending = false;
+      if (window.__rnReport) window.__rnReport();
+    });
+  }
+  function dist(t0, t1) {
+    var dx = t1.clientX - t0.clientX, dy = t1.clientY - t0.clientY;
+    return Math.sqrt(dx * dx + dy * dy);
+  }
+
+  document.addEventListener('touchstart', function (e) {
+    if (e.touches.length === 2) {
+      var t0 = e.touches[0], t1 = e.touches[1];
+      pinch = {
+        d0: dist(t0, t1) || 1,
+        s0: Z.scale,
+        cx0: (t0.clientX + t1.clientX) / 2,
+        tx0: Z.tx,
+      };
+      pan = null;
+      if (!Z.pinching) {
+        Z.pinching = true;
+        post({ type: 'zoom', pinching: true, scale: Z.scale });
+      }
+      e.preventDefault();
+    } else if (e.touches.length === 1 && Z.scale > 1.001) {
+      pan = { x0: e.touches[0].clientX, tx0: Z.tx };
+    } else {
+      pan = null;
+    }
+  }, { passive: false, capture: true });
+
+  document.addEventListener('touchmove', function (e) {
+    if (pinch && e.touches.length === 2) {
+      e.preventDefault();
+      var t0 = e.touches[0], t1 = e.touches[1];
+      var z = pinch.s0 * (dist(t0, t1) / pinch.d0);
+      if (z < 1) z = 1;
+      if (z > MAX_ZOOM) z = MAX_ZOOM;
+      // Keep the content under the fingers' midpoint stationary horizontally:
+      // the wrapper-local point that started under cx0 must map back to the
+      // current midpoint at the new scale. (applyTransform clamps the result.)
+      var cx = (t0.clientX + t1.clientX) / 2;
+      var local = (pinch.cx0 - pinch.tx0) / (Z.fit * pinch.s0);
+      Z.scale = z;
+      Z.tx = cx - local * (Z.fit * z);
+      apply();
+      scheduleReport();
+    } else if (pan && e.touches.length === 1 && Z.scale > 1.001) {
+      // No preventDefault: vertical-dominant drags must keep scrolling the
+      // native ScrollView around the WebView. Horizontal-dominant drags stay
+      // inside the WebView and pan here.
+      Z.tx = pan.tx0 + (e.touches[0].clientX - pan.x0);
+      apply();
+    }
+  }, { passive: false, capture: true });
+
+  function onTouchEnd(e) {
+    if (pinch && e.touches.length < 2) {
+      pinch = null;
+      // Snap back to the fitted layout when the pinch ends near scale 1.
+      if (Z.scale < 1.02) { Z.scale = 1; Z.tx = 0; }
+      Z.pinching = false;
+      apply();
+      if (window.__rnReport) window.__rnReport();
+      post({ type: 'zoom', pinching: false, scale: Z.scale });
+      // A finger left on screen continues as a pan.
+      if (e.touches.length === 1 && Z.scale > 1.001) {
+        pan = { x0: e.touches[0].clientX, tx0: Z.tx };
+      }
+    }
+    if (e.touches.length === 0) pan = null;
+  }
+  document.addEventListener('touchend', onTouchEnd, { passive: true, capture: true });
+  document.addEventListener('touchcancel', onTouchEnd, { passive: true, capture: true });
+  true;
+})();
+`;
+
+export default function EmailBodyView({ email, senderEmail, onSwipe, onZoomChange }: EmailBodyViewProps) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
   const externalContentPolicy = useSettingsStore((s) => s.externalContentPolicy);
@@ -423,12 +606,30 @@ export default function EmailBodyView({ email, senderEmail }: EmailBodyViewProps
   const applyInversion =
     !!rawHtml && renderAsDark && !hasNativeDarkMode(rawHtml);
   const injectedJs = React.useMemo(
-    () => (applyInversion ? DARK_REINVERT_SCRIPT + HEIGHT_REPORTER : HEIGHT_REPORTER),
+    () =>
+      (applyInversion ? DARK_REINVERT_SCRIPT + HEIGHT_REPORTER : HEIGHT_REPORTER)
+      + SWIPE_DETECTOR + PINCH_ZOOM,
     [applyInversion],
   );
 
   const onMessage = (e: WebViewMessageEvent) => {
-    const parsed = parseInt(e.nativeEvent.data, 10);
+    const data = e.nativeEvent.data;
+    // Swipe/zoom messages arrive as JSON; the height reporter posts a bare number.
+    if (data.charCodeAt(0) === 123 /* '{' */) {
+      try {
+        const msg = JSON.parse(data);
+        if (msg.type === 'swipe' && (msg.dir === 'prev' || msg.dir === 'next')) {
+          onSwipe?.(msg.dir);
+        } else if (msg.type === 'zoom') {
+          onZoomChange?.({
+            pinching: !!msg.pinching,
+            zoomed: typeof msg.scale === 'number' && msg.scale > 1.01,
+          });
+        }
+      } catch { /* ignore malformed */ }
+      return;
+    }
+    const parsed = parseInt(data, 10);
     if (Number.isNaN(parsed) || parsed <= 0) return;
     setHeight((prev) => (Math.abs(parsed - prev) < 2 ? prev : parsed));
   };
@@ -473,6 +674,10 @@ export default function EmailBodyView({ email, senderEmail }: EmailBodyViewProps
           injectedJavaScript={injectedJs}
           onMessage={onMessage}
           onLoadEnd={() => {
+            // A (re)load resets the page's zoom state to 1 — drop any host-side
+            // scroll locks so they can't go stale (e.g. cid images arriving
+            // reload the source mid-zoom).
+            onZoomChange?.({ pinching: false, zoomed: false });
             // Re-inject after load to cover Android cases where
             // `injectedJavaScript` runs too early to see the final layout. The
             // re-inversion pass guards itself (__rnDarkInvertDone) so running it
@@ -482,6 +687,9 @@ export default function EmailBodyView({ email, senderEmail }: EmailBodyViewProps
             }, 50);
           }}
           scrollEnabled={false}
+          // Native Android zoom would scale the viewport inside the fixed-size
+          // container; pinch zoom is implemented in the page instead.
+          setBuiltInZoomControls={false}
           showsVerticalScrollIndicator={false}
           showsHorizontalScrollIndicator={false}
           setSupportMultipleWindows={false}

src/components/calendar/AgendaView.tsx

@@ -1,15 +1,16 @@
 import React from 'react';
 import { SectionList, StyleSheet, Text, View } from 'react-native';
-import { format, isSameDay, isToday, isTomorrow } from 'date-fns';
+import { addDays, format, isSameDay, isToday, isTomorrow, parseISO, startOfDay } from 'date-fns';
 import { CalendarDays } from 'lucide-react-native';
 import type { Calendar, CalendarEvent } from '../../api/types';
 import { spacing, typography, type ThemePalette } from '../../theme/tokens';
 import { useColors } from '../../theme/colors';
 import {
   buildEventDayIndex,
+  dayKey,
   eventsOnDayFromIndex,
-  getEventStartDate,
   type EventDayIndex,
+  type TimeFormat,
 } from '../../lib/calendar-utils';
 import { EventCard } from './EventCard';
 
@@ -19,6 +20,7 @@ interface AgendaViewProps {
   events: CalendarEvent[];
   calendars: Calendar[];
   eventsByDay?: EventDayIndex;
+  timeFormat?: TimeFormat;
   onSelectEvent?: (event: CalendarEvent) => void;
 }
 
@@ -40,6 +42,7 @@ export function AgendaView({
   events,
   calendars,
   eventsByDay,
+  timeFormat,
   onSelectEvent,
 }: AgendaViewProps) {
   const c = useColors();
@@ -50,32 +53,35 @@ export function AgendaView({
   );
 
   const sections = React.useMemo<DaySection[]>(() => {
-    const result: DaySection[] = [];
-    const start = new Date(fromDate);
-    start.setHours(0, 0, 0, 0);
+    // Mirror webmail's agenda (calendar-agenda-view.tsx): build a group for
+    // every day that actually has events, always include a "Today" anchor, and
+    // render them sorted ascending. Driving the list off the events (rather than
+    // a fixed day-counter) guarantees every upcoming loaded event appears - not
+    // just the ones inside a brittle N-day window from the anchor.
+    const anchor = startOfDay(fromDate);
+    const horizonEnd = addDays(anchor, daysAhead); // safety bound (exclusive)
 
-    for (let i = 0; i < daysAhead; i++) {
-      const day = new Date(start);
-      day.setDate(start.getDate() + i);
-      const dayEvents = eventsOnDayFromIndex(index, day).slice().sort((a, b) => {
-        // All-day events first within a day, then by start time, then title
-        // (stable tie-break) - mirrors the comparator the webmail uses for
-        // packing week segments and keeps multi-event days predictable.
-        if (a.showWithoutTime !== b.showWithoutTime) {
-          return a.showWithoutTime ? -1 : 1;
-        }
-        const diff = getEventStartDate(a).getTime() - getEventStartDate(b).getTime();
-        if (diff !== 0) return diff;
-        return (a.title || '').localeCompare(b.title || '');
-      });
-      if (dayEvents.length === 0 && !isToday(day)) continue;
-      result.push({
+    const days = new Map<string, Date>();
+    for (const key of index.keys()) {
+      const day = parseISO(key); // index keys are local yyyy-MM-dd
+      if (isNaN(day.getTime())) continue;
+      if (day < anchor || day >= horizonEnd) continue;
+      days.set(key, day);
+    }
+    // Always anchor "Today" so the view has a stable starting point even when
+    // the current day has no events (webmail injects the same anchor).
+    const today = startOfDay(new Date());
+    if (today >= anchor && today < horizonEnd) days.set(dayKey(today), today);
+
+    return [...days.values()]
+      .sort((a, b) => a.getTime() - b.getTime())
+      .map((day) => ({
         title: formatDayHeader(day),
         date: day,
-        data: dayEvents,
-      });
-    }
-    return result;
+        // Buckets are pre-sorted by buildEventDayIndex (all-day first, then by
+        // start, then title), so no extra sort is needed here.
+        data: eventsOnDayFromIndex(index, day),
+      }));
   }, [fromDate, daysAhead, index]);
 
   if (sections.length === 0) {
@@ -107,7 +113,7 @@ export function AgendaView({
       }}
       renderItem={({ item }) => (
         <View style={styles.itemWrap}>
-          <EventCard event={item} calendars={calendars} onPress={onSelectEvent} />
+          <EventCard event={item} calendars={calendars} timeFormat={timeFormat} onPress={onSelectEvent} />
         </View>
       )}
       renderSectionFooter={({ section }) =>

src/components/calendar/CalendarSidebarDrawer.tsx

@@ -11,12 +11,13 @@ import {
   View,
 } from 'react-native';
 import { SafeAreaView } from 'react-native-safe-area-context';
-import { Check, X, Upload, Rss } from 'lucide-react-native';
+import { Check, X, Upload, Rss, Shuffle, Star } from 'lucide-react-native';
 import type { Calendar } from '../../api/types';
 import { radius, spacing, typography, type ThemePalette } from '../../theme/tokens';
 import { useColors } from '../../theme/colors';
 import { useAnimDuration } from '../../theme/dynamic';
-import { getCalendarColor } from '../../lib/calendar-utils';
+import { CALENDAR_COLOR_PALETTE, getCalendarColor } from '../../lib/calendar-utils';
+import { BIRTHDAY_CALENDAR_ID } from '../../lib/birthday-calendar';
 
 interface CalendarSidebarDrawerProps {
   visible: boolean;
@@ -26,6 +27,11 @@ interface CalendarSidebarDrawerProps {
   onClose: () => void;
   onImport?: () => void;
   onManageSubscriptions?: () => void;
+  // Long-press actions. Set-default applies to the user's own calendars;
+  // color change/reset applies to shared calendars (per-viewer recolor).
+  onSetDefault?: (calendar: Calendar) => void;
+  onSetColor?: (calendar: Calendar, color: string) => void;
+  onResetColor?: (calendar: Calendar) => void;
 }
 
 export function CalendarSidebarDrawer({
@@ -36,6 +42,9 @@ export function CalendarSidebarDrawer({
   onClose,
   onImport,
   onManageSubscriptions,
+  onSetDefault,
+  onSetColor,
+  onResetColor,
 }: CalendarSidebarDrawerProps) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
@@ -43,6 +52,7 @@ export function CalendarSidebarDrawer({
   const overlayOpacity = React.useRef(new Animated.Value(0)).current;
   const openDuration = useAnimDuration(240);
   const closeDuration = useAnimDuration(200);
+  const [expandedId, setExpandedId] = React.useState<string | null>(null);
 
   React.useEffect(() => {
     if (visible) {
@@ -60,6 +70,7 @@ export function CalendarSidebarDrawer({
         }),
       ]).start();
     } else {
+      setExpandedId(null);
       Animated.parallel([
         Animated.timing(slideX, {
           toValue: -Dimensions.get('window').width,
@@ -78,8 +89,23 @@ export function CalendarSidebarDrawer({
 
   const hiddenSet = React.useMemo(() => new Set(hiddenCalendarIds), [hiddenCalendarIds]);
 
-  const myCalendars = calendars.filter((c) => !c.myRights || c.myRights.mayWrite !== false);
-  const subscribed = calendars.filter((c) => c.myRights && c.myRights.mayWrite === false);
+  const sharedCalendars = calendars.filter((cal) => cal.isShared);
+  const myCalendars = calendars.filter(
+    (cal) => !cal.isShared && (!cal.myRights || cal.myRights.mayWrite !== false),
+  );
+  const subscribed = calendars.filter(
+    (cal) => !cal.isShared && cal.myRights && cal.myRights.mayWrite === false,
+  );
+
+  const sectionProps = {
+    hiddenSet,
+    onToggle,
+    expandedId,
+    onExpand: setExpandedId,
+    onSetDefault,
+    onSetColor,
+    onResetColor,
+  };
 
   return (
     <Modal
@@ -110,21 +136,15 @@ export function CalendarSidebarDrawer({
             )}
 
             {myCalendars.length > 0 && (
-              <Section
-                title="My calendars"
-                calendars={myCalendars}
-                hiddenSet={hiddenSet}
-                onToggle={onToggle}
-              />
+              <Section title="My calendars" calendars={myCalendars} {...sectionProps} />
+            )}
+
+            {sharedCalendars.length > 0 && (
+              <Section title="Shared with me" calendars={sharedCalendars} {...sectionProps} />
             )}
 
             {subscribed.length > 0 && (
-              <Section
-                title="Subscribed"
-                calendars={subscribed}
-                hiddenSet={hiddenSet}
-                onToggle={onToggle}
-              />
+              <Section title="Subscribed" calendars={subscribed} {...sectionProps} />
             )}
 
             {(onImport || onManageSubscriptions) && (
@@ -161,11 +181,21 @@ function Section({
   calendars,
   hiddenSet,
   onToggle,
+  expandedId,
+  onExpand,
+  onSetDefault,
+  onSetColor,
+  onResetColor,
 }: {
   title: string;
   calendars: Calendar[];
   hiddenSet: Set<string>;
   onToggle: (id: string) => void;
+  expandedId: string | null;
+  onExpand: (id: string | null) => void;
+  onSetDefault?: (calendar: Calendar) => void;
+  onSetColor?: (calendar: Calendar, color: string) => void;
+  onResetColor?: (calendar: Calendar) => void;
 }) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
@@ -174,30 +204,85 @@ function Section({
       <Text style={styles.sectionTitle}>{title}</Text>
       {calendars.map((cal) => {
         const visible = !hiddenSet.has(cal.id);
+        const isBirthday = cal.id === BIRTHDAY_CALENDAR_ID;
+        const canSetDefault = !!onSetDefault && !cal.isShared && !isBirthday && !cal.isDefault;
+        const canRecolor = !!onSetColor && !!cal.isShared;
+        const hasActions = canSetDefault || canRecolor;
+        const expanded = expandedId === cal.id && hasActions;
         return (
-          <Pressable
-            key={cal.id}
-            onPress={() => onToggle(cal.id)}
-            style={({ pressed }) => [
-              styles.row,
-              pressed && styles.rowPressed,
-            ]}
-          >
-            <View
-              style={[
-                styles.swatch,
-                {
-                  backgroundColor: visible ? getCalendarColor(cal) : 'transparent',
-                  borderColor: getCalendarColor(cal),
-                },
+          <View key={cal.id}>
+            <Pressable
+              onPress={() => onToggle(cal.id)}
+              onLongPress={hasActions ? () => onExpand(expanded ? null : cal.id) : undefined}
+              style={({ pressed }) => [
+                styles.row,
+                pressed && styles.rowPressed,
               ]}
             >
-              {visible && <Check size={12} color={c.textInverse} />}
-            </View>
-            <Text style={[styles.rowName, !visible && styles.rowNameMuted]}>
-              {cal.name}
-            </Text>
-          </Pressable>
+              <View
+                style={[
+                  styles.swatch,
+                  {
+                    backgroundColor: visible ? getCalendarColor(cal) : 'transparent',
+                    borderColor: getCalendarColor(cal),
+                  },
+                ]}
+              >
+                {visible && <Check size={12} color={c.textInverse} />}
+              </View>
+              <Text style={[styles.rowName, !visible && styles.rowNameMuted]} numberOfLines={1}>
+                {cal.name}
+              </Text>
+              {cal.isDefault && !cal.isShared && (
+                <Star size={14} color={c.textMuted} fill={c.textMuted} />
+              )}
+            </Pressable>
+
+            {expanded && (
+              <View style={styles.actionsPanel}>
+                {canSetDefault && (
+                  <Pressable
+                    onPress={() => { onExpand(null); onSetDefault!(cal); }}
+                    style={({ pressed }) => [styles.panelRow, pressed && styles.rowPressed]}
+                  >
+                    <Star size={16} color={c.textSecondary} />
+                    <Text style={styles.panelRowText}>Set as default calendar</Text>
+                  </Pressable>
+                )}
+                {canRecolor && (
+                  <>
+                    <View style={styles.paletteRow}>
+                      {CALENDAR_COLOR_PALETTE.map((color) => {
+                        const active = cal.color?.toLowerCase() === color.toLowerCase();
+                        return (
+                          <Pressable
+                            key={color}
+                            onPress={() => { onExpand(null); onSetColor!(cal, color); }}
+                            style={[
+                              styles.paletteSwatch,
+                              { backgroundColor: color },
+                              active && styles.paletteSwatchActive,
+                            ]}
+                          >
+                            {active && <Check size={12} color={c.textInverse} />}
+                          </Pressable>
+                        );
+                      })}
+                    </View>
+                    {!!onResetColor && cal.colorIsLocalOverride && (
+                      <Pressable
+                        onPress={() => { onExpand(null); onResetColor(cal); }}
+                        style={({ pressed }) => [styles.panelRow, pressed && styles.rowPressed]}
+                      >
+                        <Shuffle size={16} color={c.textSecondary} />
+                        <Text style={styles.panelRowText}>Random color</Text>
+                      </Pressable>
+                    )}
+                  </>
+                )}
+              </View>
+            )}
+          </View>
         );
       })}
     </View>
@@ -279,6 +364,43 @@ function makeStyles(c: ThemePalette) {
   rowName: { flex: 1, ...typography.body, color: c.text },
   rowNameMuted: { color: c.textMuted },
 
+  actionsPanel: {
+    marginHorizontal: spacing.lg,
+    marginBottom: spacing.sm,
+    borderWidth: 1,
+    borderColor: c.border,
+    borderRadius: radius.sm,
+    backgroundColor: c.surface,
+    overflow: 'hidden',
+  },
+  panelRow: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    gap: spacing.sm,
+    paddingHorizontal: spacing.md,
+    paddingVertical: spacing.sm,
+    minHeight: 40,
+  },
+  panelRowText: { ...typography.body, color: c.text },
+  paletteRow: {
+    flexDirection: 'row',
+    flexWrap: 'wrap',
+    gap: spacing.sm,
+    paddingHorizontal: spacing.md,
+    paddingVertical: spacing.sm,
+  },
+  paletteSwatch: {
+    width: 24,
+    height: 24,
+    borderRadius: radius.full,
+    alignItems: 'center',
+    justifyContent: 'center',
+  },
+  paletteSwatchActive: {
+    borderWidth: 2,
+    borderColor: c.text,
+  },
+
   actionsSection: {
     marginTop: spacing.lg,
     paddingTop: spacing.sm,

src/components/calendar/EventCard.tsx

@@ -5,11 +5,17 @@ import { format } from 'date-fns';
 import type { Calendar, CalendarEvent } from '../../api/types';
 import { radius, spacing, typography, type ThemePalette } from '../../theme/tokens';
 import { useColors } from '../../theme/colors';
-import { eventTimeRange, getEventColor } from '../../lib/calendar-utils';
+import {
+  eventTimeRange,
+  getEventColor,
+  timePattern,
+  type TimeFormat,
+} from '../../lib/calendar-utils';
 
 interface EventCardProps {
   event: CalendarEvent;
   calendars: Calendar[];
+  timeFormat?: TimeFormat;
   onPress?: (event: CalendarEvent) => void;
   onLongPress?: (event: CalendarEvent) => void;
 }
@@ -18,17 +24,18 @@ function participantCount(event: CalendarEvent): number {
   return event.participants ? Object.keys(event.participants).length : 0;
 }
 
-function formatTimeRange(event: CalendarEvent): string {
+function formatTimeRange(event: CalendarEvent, timeFormat?: TimeFormat): string {
   const { start, end, allDay } = eventTimeRange(event);
   if (allDay) return 'All day';
-  return `${format(start, 'HH:mm')} – ${format(end, 'HH:mm')}`;
+  const fmt = timePattern(timeFormat);
+  return `${format(start, fmt)} – ${format(end, fmt)}`;
 }
 
-export function EventCard({ event, calendars, onPress, onLongPress }: EventCardProps) {
+export function EventCard({ event, calendars, timeFormat, onPress, onLongPress }: EventCardProps) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
   const color = getEventColor(event, calendars);
-  const time = formatTimeRange(event);
+  const time = formatTimeRange(event, timeFormat);
   const count = participantCount(event);
 
   return (

src/components/calendar/EventDetailSheet.tsx

@@ -36,6 +36,8 @@ import {
   eventTimeRange,
   getEventColor,
   getPrimaryCalendarId,
+  timePattern,
+  type TimeFormat,
 } from '../../lib/calendar-utils';
 import { alertsToReminders, formatReminder } from '../../lib/calendar-alerts';
 import {
@@ -50,6 +52,7 @@ type RsvpStatus = 'accepted' | 'declined' | 'tentative';
 interface EventDetailSheetProps {
   event: CalendarEvent | null;
   calendars: Calendar[];
+  timeFormat?: TimeFormat;
   onClose: () => void;
   onEdit?: (event: CalendarEvent) => void;
   onDelete?: (event: CalendarEvent) => void;
@@ -57,7 +60,7 @@ interface EventDetailSheetProps {
   onRsvp?: (event: CalendarEvent, participantId: string, status: RsvpStatus) => void | Promise<void>;
 }
 
-function formatRange(event: CalendarEvent): string {
+function formatRange(event: CalendarEvent, timeFormat?: TimeFormat): string {
   const { start, end, allDay } = eventTimeRange(event);
   if (allDay) {
     if (
@@ -69,14 +72,15 @@ function formatRange(event: CalendarEvent): string {
     }
     return `${format(start, 'MMM d')} – ${format(end, 'MMM d, yyyy')}`;
   }
+  const t = timePattern(timeFormat);
   const sameDay =
     start.getFullYear() === end.getFullYear() &&
     start.getMonth() === end.getMonth() &&
     start.getDate() === end.getDate();
   if (sameDay) {
-    return `${format(start, 'EEE, MMM d')} · ${format(start, 'HH:mm')} – ${format(end, 'HH:mm')}`;
+    return `${format(start, 'EEE, MMM d')} · ${format(start, t)} – ${format(end, t)}`;
   }
-  return `${format(start, 'MMM d, HH:mm')} – ${format(end, 'MMM d, HH:mm')}`;
+  return `${format(start, `MMM d, ${t}`)} – ${format(end, `MMM d, ${t}`)}`;
 }
 
 function recurrenceLabel(event: CalendarEvent): string | null {
@@ -100,6 +104,7 @@ function recurrenceLabel(event: CalendarEvent): string | null {
 export function EventDetailSheet({
   event,
   calendars,
+  timeFormat,
   onClose,
   onEdit,
   onDelete,
@@ -156,7 +161,7 @@ export function EventDetailSheet({
   const color = getEventColor(event, calendars);
   const calendarId = getPrimaryCalendarId(event);
   const calendar = calendars.find((c) => c.id === calendarId);
-  const range = formatRange(event);
+  const range = formatRange(event, timeFormat);
   const recurrence = recurrenceLabel(event);
   const reminders = alertsToReminders(event.alerts);
   const participants = event.participants ? Object.values(event.participants) : [];

src/components/calendar/EventModal.tsx

@@ -31,6 +31,7 @@ import type {
   CalendarEvent,
   Participant,
   EventLocation,
+  RecurrenceRule,
   VirtualLocation,
 } from '../../api/types';
 import { radius, spacing, typography, type ThemePalette } from '../../theme/tokens';
@@ -49,10 +50,12 @@ import {
   REMINDER_PRESETS,
   type Reminder,
 } from '../../lib/calendar-alerts';
+import { buildRecurrenceSummary, isSimpleRecurrenceRule } from '../../lib/recurrence';
 import { Button } from '..';
 import { ParticipantInput } from './ParticipantInput';
+import { RecurrenceEditor } from './RecurrenceEditor';
 
-type RecurrenceOption = 'none' | 'daily' | 'weekly' | 'monthly' | 'yearly';
+type RecurrenceOption = 'none' | 'daily' | 'weekly' | 'monthly' | 'yearly' | 'custom';
 
 const RECURRENCE_OPTIONS: { value: RecurrenceOption; label: string }[] = [
   { value: 'none', label: 'Does not repeat' },
@@ -60,6 +63,7 @@ const RECURRENCE_OPTIONS: { value: RecurrenceOption; label: string }[] = [
   { value: 'weekly', label: 'Weekly' },
   { value: 'monthly', label: 'Monthly' },
   { value: 'yearly', label: 'Yearly' },
+  { value: 'custom', label: 'Custom…' },
 ];
 
 interface EventModalProps {
@@ -99,11 +103,15 @@ function buildDuration(start: Date, end: Date): string {
 function detectRecurrence(event: CalendarEvent | null | undefined): RecurrenceOption {
   const rule = event?.recurrenceRules?.[0];
   if (!rule) return 'none';
-  const f = rule.frequency.toLowerCase();
-  if (f === 'daily' || f === 'weekly' || f === 'monthly' || f === 'yearly') {
-    return f as RecurrenceOption;
+  if (isSimpleRecurrenceRule(rule)) {
+    const f = rule.frequency.toLowerCase();
+    if (f === 'daily' || f === 'weekly' || f === 'monthly' || f === 'yearly') {
+      return f as RecurrenceOption;
+    }
   }
-  return 'none';
+  // Anything the simple presets can't represent is edited via the custom
+  // recurrence editor.
+  return 'custom';
 }
 
 function detectLocation(event: CalendarEvent | null | undefined): string {
@@ -156,9 +164,18 @@ export function EventModal({
   const [allDay, setAllDay] = React.useState(false);
   const [start, setStart] = React.useState<Date>(() => nextHalfHour(defaultDate ?? new Date()));
   const [end, setEnd] = React.useState<Date>(() => addHours(nextHalfHour(defaultDate ?? new Date()), 1));
-  const [calendarId, setCalendarId] = React.useState<string>(defaultCalendarId || calendars[0]?.id || '');
+  // New events land in the explicitly requested calendar, else the account's
+  // default calendar, else the first one.
+  const fallbackCalendarId =
+    defaultCalendarId
+    || calendars.find((cal) => cal.isDefault && !cal.isShared)?.id
+    || calendars[0]?.id
+    || '';
+  const [calendarId, setCalendarId] = React.useState<string>(fallbackCalendarId);
   const [participants, setParticipants] = React.useState<Record<string, Participant>>({});
   const [recurrence, setRecurrence] = React.useState<RecurrenceOption>('none');
+  const [customRule, setCustomRule] = React.useState<RecurrenceRule | null>(null);
+  const [recurrenceEditorOpen, setRecurrenceEditorOpen] = React.useState(false);
   const [reminders, setReminders] = React.useState<Reminder[]>([]);
   const [location, setLocation] = React.useState('');
   const [videoUrl, setVideoUrl] = React.useState('');
@@ -181,7 +198,10 @@ export function EventModal({
       setEnd(getEventEndDate(event));
       setCalendarId(getPrimaryCalendarId(event) || calendars[0]?.id || '');
       setParticipants(event.participants || {});
-      setRecurrence(detectRecurrence(event));
+      const detected = detectRecurrence(event);
+      setRecurrence(detected);
+      setCustomRule(detected === 'custom' ? event.recurrenceRules?.[0] ?? null : null);
+      setRecurrenceEditorOpen(false);
       setReminders(alertsToReminders(event.alerts));
       setLocation(detectLocation(event));
       setVideoUrl(detectVideoUrl(event));
@@ -192,9 +212,16 @@ export function EventModal({
       setAllDay(false);
       setStart(d);
       setEnd(addHours(d, 1));
-      setCalendarId(defaultCalendarId || calendars[0]?.id || '');
+      setCalendarId(
+        defaultCalendarId
+        || calendars.find((cal) => cal.isDefault && !cal.isShared)?.id
+        || calendars[0]?.id
+        || '',
+      );
       setParticipants({});
       setRecurrence('none');
+      setCustomRule(null);
+      setRecurrenceEditorOpen(false);
       setReminders([]);
       setLocation('');
       setVideoUrl('');
@@ -241,7 +268,12 @@ export function EventModal({
           : format(start, "yyyy-MM-dd'T'HH:mm:ss"),
         duration: allDay ? buildAllDayDuration(start, end) : buildDuration(start, end),
         participants: Object.keys(participants).length > 0 ? participants : undefined,
-        recurrenceRules: recurrenceFromOption(recurrence),
+        recurrenceRules:
+          recurrence === 'custom'
+            ? customRule
+              ? [customRule]
+              : undefined
+            : recurrenceFromOption(recurrence),
         alerts: remindersToAlerts(reminders),
         useDefaultAlerts: reminders.length > 0 ? false : undefined,
         locations: buildLocations(location),
@@ -259,7 +291,10 @@ export function EventModal({
   };
 
   const selectedCalendar = calendars.find((c) => c.id === calendarId);
-  const recurrenceLabel = RECURRENCE_OPTIONS.find((o) => o.value === recurrence)?.label || 'None';
+  const recurrenceLabel =
+    recurrence === 'custom'
+      ? (customRule && buildRecurrenceSummary(customRule)) || 'Custom'
+      : RECURRENCE_OPTIONS.find((o) => o.value === recurrence)?.label || 'None';
 
   const addReminder = (minutesBefore: number) => {
     setReminderPickerOpen(false);
@@ -431,8 +466,14 @@ export function EventModal({
                       opt.value === recurrence && styles.popoverRowActive,
                     ]}
                     onPress={() => {
-                      setRecurrence(opt.value);
                       setRecurrenceOpen(false);
+                      if (opt.value === 'custom') {
+                        setRecurrenceEditorOpen(true);
+                        return;
+                      }
+                      setRecurrence(opt.value);
+                      setCustomRule(null);
+                      setRecurrenceEditorOpen(false);
                     }}
                   >
                     <Text style={styles.popoverRowText}>{opt.label}</Text>
@@ -440,6 +481,23 @@ export function EventModal({
                 ))}
               </View>
             )}
+            {recurrenceEditorOpen && (
+              <RecurrenceEditor
+                rule={customRule}
+                eventStart={start}
+                onSave={(rule) => {
+                  setCustomRule(rule);
+                  setRecurrence('custom');
+                  setRecurrenceEditorOpen(false);
+                }}
+                onCancel={() => setRecurrenceEditorOpen(false)}
+              />
+            )}
+            {recurrence === 'custom' && customRule && !recurrenceEditorOpen && (
+              <Pressable style={styles.addRow} onPress={() => setRecurrenceEditorOpen(true)}>
+                <Text style={styles.addRowText}>Edit custom recurrence</Text>
+              </Pressable>
+            )}
           </Section>
 
           <Section icon={<Bell size={16} color={c.textMuted} />} label="Reminders">

src/components/calendar/RecurrenceEditor.tsx

@@ -0,0 +1,370 @@
+import React from 'react';
+import { View, Text, TextInput, Pressable, StyleSheet, Platform } from 'react-native';
+import DateTimePicker from '@react-native-community/datetimepicker';
+import { ChevronDown } from 'lucide-react-native';
+import { format, parseISO } from 'date-fns';
+import type { RecurrenceRule } from '../../api/types';
+import { radius, spacing, typography, type ThemePalette } from '../../theme/tokens';
+import { useColors } from '../../theme/colors';
+import { Button } from '..';
+import {
+  EDITOR_FREQUENCIES,
+  UNIT_LABELS,
+  WEEKDAYS,
+  buildRecurrenceSummary,
+  buildRuleFromEditorValue,
+  capitalize,
+  editorValueFromRule,
+  monthName,
+  nthLabel,
+  weekdayName,
+  type EditorFrequency,
+  type EndsMode,
+  type MonthlyMode,
+  type RecurrenceEditorValue,
+} from '../../lib/recurrence';
+
+interface RecurrenceEditorProps {
+  rule: RecurrenceRule | null;
+  eventStart: Date;
+  onSave: (rule: RecurrenceRule) => void;
+  onCancel: () => void;
+}
+
+// Small popover-style select, matching the EventModal field pattern.
+function InlineSelect<T extends string | number>({
+  value,
+  options,
+  onChange,
+  flex,
+}: {
+  value: T;
+  options: { value: T; label: string }[];
+  onChange: (value: T) => void;
+  flex?: boolean;
+}) {
+  const c = useColors();
+  const styles = React.useMemo(() => makeStyles(c), [c]);
+  const [open, setOpen] = React.useState(false);
+  const selected = options.find((o) => o.value === value);
+  return (
+    <View style={flex ? styles.selectFlex : undefined}>
+      <Pressable style={styles.selectButton} onPress={() => setOpen((v) => !v)}>
+        <Text style={styles.selectText} numberOfLines={1}>
+          {selected?.label ?? String(value)}
+        </Text>
+        <ChevronDown size={14} color={c.textMuted} />
+      </Pressable>
+      {open && (
+        <View style={styles.popover}>
+          {options.map((opt) => (
+            <Pressable
+              key={String(opt.value)}
+              style={[styles.popoverRow, opt.value === value && styles.popoverRowActive]}
+              onPress={() => {
+                onChange(opt.value);
+                setOpen(false);
+              }}
+            >
+              <Text style={styles.popoverRowText}>{opt.label}</Text>
+            </Pressable>
+          ))}
+        </View>
+      )}
+    </View>
+  );
+}
+
+function NumberInput({
+  value,
+  min,
+  max,
+  onChange,
+}: {
+  value: number;
+  min: number;
+  max: number;
+  onChange: (value: number) => void;
+}) {
+  const c = useColors();
+  const styles = React.useMemo(() => makeStyles(c), [c]);
+  const [text, setText] = React.useState(String(value));
+  React.useEffect(() => setText(String(value)), [value]);
+  return (
+    <TextInput
+      value={text}
+      onChangeText={setText}
+      onEndEditing={() => {
+        const n = parseInt(text, 10);
+        const clamped = Number.isFinite(n) ? Math.min(max, Math.max(min, n)) : min;
+        setText(String(clamped));
+        onChange(clamped);
+      }}
+      keyboardType="number-pad"
+      style={styles.numberInput}
+    />
+  );
+}
+
+export function RecurrenceEditor({ rule, eventStart, onSave, onCancel }: RecurrenceEditorProps) {
+  const c = useColors();
+  const styles = React.useMemo(() => makeStyles(c), [c]);
+
+  const [value, setValue] = React.useState<RecurrenceEditorValue>(() =>
+    editorValueFromRule(rule, eventStart),
+  );
+  const [showUntilPicker, setShowUntilPicker] = React.useState(false);
+
+  const update = (patch: Partial<RecurrenceEditorValue>) =>
+    setValue((prev) => ({ ...prev, ...patch }));
+
+  const toggleWeekDay = (day: string) => {
+    setValue((prev) => ({
+      ...prev,
+      weekDays: prev.weekDays.includes(day)
+        ? prev.weekDays.length > 1
+          ? prev.weekDays.filter((d) => d !== day)
+          : prev.weekDays
+        : [...prev.weekDays, day],
+    }));
+  };
+
+  const builtRule = buildRuleFromEditorValue(value, eventStart);
+  const summary = buildRecurrenceSummary(builtRule);
+
+  return (
+    <View style={styles.container}>
+      <View style={styles.row}>
+        <Text style={styles.rowLabel}>Every</Text>
+        <NumberInput
+          value={value.interval}
+          min={1}
+          max={999}
+          onChange={(interval) => update({ interval })}
+        />
+        <InlineSelect<EditorFrequency>
+          flex
+          value={value.frequency}
+          options={EDITOR_FREQUENCIES.map((f) => ({ value: f, label: UNIT_LABELS[f] }))}
+          onChange={(frequency) => update({ frequency })}
+        />
+      </View>
+
+      {value.frequency === 'weekly' && (
+        <View style={styles.weekdayRow}>
+          {WEEKDAYS.map((day) => {
+            const active = value.weekDays.includes(day);
+            return (
+              <Pressable
+                key={day}
+                onPress={() => toggleWeekDay(day)}
+                style={[styles.weekdayChip, active && styles.weekdayChipActive]}
+              >
+                <Text style={[styles.weekdayChipText, active && styles.weekdayChipTextActive]}>
+                  {weekdayName(day, 'short')}
+                </Text>
+              </Pressable>
+            );
+          })}
+        </View>
+      )}
+
+      {value.frequency === 'yearly' && (
+        <View style={styles.row}>
+          <Text style={styles.rowLabel}>In</Text>
+          <InlineSelect<number>
+            flex
+            value={value.month}
+            options={Array.from({ length: 12 }, (_, i) => i + 1).map((m) => ({
+              value: m,
+              label: capitalize(monthName(m)),
+            }))}
+            onChange={(month) => update({ month })}
+          />
+        </View>
+      )}
+
+      {(value.frequency === 'monthly' || value.frequency === 'yearly') && (
+        <View style={styles.row}>
+          <InlineSelect<MonthlyMode>
+            value={value.monthlyMode}
+            options={[
+              { value: 'day', label: 'On day' },
+              { value: 'nth', label: 'On the' },
+            ]}
+            onChange={(monthlyMode) => update({ monthlyMode })}
+          />
+          {value.monthlyMode === 'day' ? (
+            <NumberInput
+              value={value.monthDay}
+              min={1}
+              max={31}
+              onChange={(monthDay) => update({ monthDay })}
+            />
+          ) : (
+            <>
+              <InlineSelect<number>
+                flex
+                value={value.nth}
+                options={[1, 2, 3, 4, -1].map((n) => ({ value: n, label: capitalize(nthLabel(n)) }))}
+                onChange={(nth) => update({ nth })}
+              />
+              <InlineSelect<string>
+                flex
+                value={value.nthDay}
+                options={WEEKDAYS.map((d) => ({ value: d, label: capitalize(weekdayName(d)) }))}
+                onChange={(nthDay) => update({ nthDay })}
+              />
+            </>
+          )}
+        </View>
+      )}
+
+      <View style={styles.row}>
+        <Text style={styles.rowLabel}>Ends</Text>
+        <InlineSelect<EndsMode>
+          flex={value.endsMode === 'never'}
+          value={value.endsMode}
+          options={[
+            { value: 'never', label: 'Never' },
+            { value: 'on', label: 'On date' },
+            { value: 'after', label: 'After' },
+          ]}
+          onChange={(endsMode) => update({ endsMode })}
+        />
+        {value.endsMode === 'on' && (
+          <Pressable style={[styles.selectButton, styles.selectFlex]} onPress={() => setShowUntilPicker(true)}>
+            <Text style={styles.selectText}>
+              {format(parseISO(value.untilDate), 'MMM d, yyyy')}
+            </Text>
+          </Pressable>
+        )}
+        {value.endsMode === 'after' && (
+          <>
+            <NumberInput
+              value={value.count}
+              min={1}
+              max={999}
+              onChange={(count) => update({ count })}
+            />
+            <Text style={styles.muted}>occurrences</Text>
+          </>
+        )}
+      </View>
+
+      <View style={styles.footer}>
+        <Text style={styles.summary} numberOfLines={2}>
+          {summary}
+        </Text>
+        <View style={styles.footerButtons}>
+          <Button variant="outline" size="sm" onPress={onCancel}>
+            Cancel
+          </Button>
+          <Button variant="default" size="sm" onPress={() => onSave(builtRule)}>
+            Done
+          </Button>
+        </View>
+      </View>
+
+      {showUntilPicker && (
+        <DateTimePicker
+          value={parseISO(value.untilDate)}
+          mode="date"
+          display={Platform.OS === 'ios' ? 'spinner' : 'default'}
+          onChange={(_, d) => {
+            setShowUntilPicker(false);
+            if (d) update({ untilDate: format(d, 'yyyy-MM-dd') });
+          }}
+        />
+      )}
+    </View>
+  );
+}
+
+function makeStyles(c: ThemePalette) {
+  return StyleSheet.create({
+    container: {
+      borderWidth: 1,
+      borderColor: c.border,
+      borderRadius: radius.sm,
+      backgroundColor: c.surface,
+      padding: spacing.md,
+      gap: spacing.sm,
+    },
+    row: { flexDirection: 'row', alignItems: 'center', gap: spacing.sm },
+    rowLabel: { ...typography.body, color: c.textSecondary },
+    muted: { ...typography.caption, color: c.textMuted, flexShrink: 1 },
+
+    numberInput: {
+      minWidth: 52,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.xs,
+      borderRadius: radius.xs,
+      borderWidth: 1,
+      borderColor: c.border,
+      backgroundColor: c.background,
+      color: c.text,
+      ...typography.body,
+      textAlign: 'center',
+    },
+
+    selectFlex: { flex: 1, minWidth: 0 },
+    selectButton: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      justifyContent: 'space-between',
+      gap: spacing.xs,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.xs,
+      minHeight: 36,
+      borderRadius: radius.xs,
+      borderWidth: 1,
+      borderColor: c.border,
+      backgroundColor: c.background,
+    },
+    selectText: { ...typography.body, color: c.text, flexShrink: 1 },
+
+    popover: {
+      marginTop: spacing.xs,
+      borderWidth: 1,
+      borderColor: c.border,
+      borderRadius: radius.xs,
+      backgroundColor: c.background,
+      overflow: 'hidden',
+    },
+    popoverRow: {
+      paddingHorizontal: spacing.md,
+      paddingVertical: spacing.sm,
+      borderBottomWidth: 1,
+      borderBottomColor: c.borderLight,
+    },
+    popoverRowActive: { backgroundColor: c.primaryBg },
+    popoverRowText: { ...typography.body, color: c.text },
+
+    weekdayRow: { flexDirection: 'row', gap: 4 },
+    weekdayChip: {
+      flex: 1,
+      minWidth: 0,
+      paddingVertical: spacing.xs,
+      borderRadius: radius.xs,
+      borderWidth: 1,
+      borderColor: c.border,
+      alignItems: 'center',
+    },
+    weekdayChipActive: {
+      borderColor: c.primary,
+      backgroundColor: c.primaryBg,
+    },
+    weekdayChipText: { ...typography.caption, color: c.textMuted },
+    weekdayChipTextActive: { color: c.primary },
+
+    footer: {
+      borderTopWidth: 1,
+      borderTopColor: c.border,
+      paddingTop: spacing.sm,
+      gap: spacing.sm,
+    },
+    summary: { ...typography.caption, color: c.textMuted },
+    footerButtons: { flexDirection: 'row', justifyContent: 'flex-end', gap: spacing.sm },
+  });
+}

src/components/files/ShareSheet.tsx

@@ -0,0 +1,425 @@
+import React, { useCallback, useEffect, useMemo, useState } from 'react';
+import {
+  ActivityIndicator,
+  Alert,
+  Modal,
+  Pressable,
+  ScrollView,
+  StyleSheet,
+  Text,
+  TextInput,
+  TouchableWithoutFeedback,
+  View,
+} from 'react-native';
+import { Folder, FileText, Trash2, UserPlus, Users } from 'lucide-react-native';
+
+import { getPrincipals, isFolder, ownPrincipalId, setFileNodeShare } from '../../api/files';
+import type { FileNode, FileNodeRights, Principal } from '../../api/types';
+import { spacing, radius, typography, type ThemePalette } from '../../theme/tokens';
+import { useColors } from '../../theme/colors';
+
+type RolePreset = 'read' | 'readWrite' | 'manager';
+
+// Same presets the webmail's share dialog offers (#408). "custom" rights set
+// by another client are shown as-is and left untouched until the user picks a
+// preset for that principal.
+const FILE_PRESETS: Record<RolePreset, 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,
+  },
+};
+
+const PRESET_LABELS: Record<RolePreset, string> = {
+  read: 'Viewer',
+  readWrite: 'Editor',
+  manager: 'Manager',
+};
+
+const PRESET_ORDER: RolePreset[] = ['read', 'readWrite', 'manager'];
+
+function detectPreset(rights: FileNodeRights): RolePreset | 'custom' {
+  for (const preset of PRESET_ORDER) {
+    const expected = FILE_PRESETS[preset];
+    const keys = Object.keys(expected) as (keyof FileNodeRights)[];
+    if (keys.every((k) => expected[k] === (rights[k] ?? false))) return preset;
+  }
+  return 'custom';
+}
+
+interface ShareSheetProps {
+  node: FileNode | null;
+  onClose: () => void;
+  /** Fired after any successful share change so the parent can refresh. */
+  onChanged: () => void;
+}
+
+export default function ShareSheet({ node, onClose, onChanged }: ShareSheetProps) {
+  const c = useColors();
+  const styles = React.useMemo(() => makeStyles(c), [c]);
+
+  const [principals, setPrincipals] = useState<Principal[]>([]);
+  const [loadingPrincipals, setLoadingPrincipals] = useState(false);
+  const [shares, setShares] = useState<Record<string, FileNodeRights>>({});
+  const [search, setSearch] = useState('');
+  const [savingId, setSavingId] = useState<string | null>(null);
+
+  useEffect(() => {
+    if (!node) return;
+    setShares(node.shareWith ?? {});
+    setSearch('');
+    setLoadingPrincipals(true);
+    getPrincipals()
+      .then(setPrincipals)
+      .catch(() => setPrincipals([]))
+      .finally(() => setLoadingPrincipals(false));
+  }, [node]);
+
+  const principalsById = useMemo(() => {
+    const map = new Map<string, Principal>();
+    for (const p of principals) map.set(p.id, p);
+    return map;
+  }, [principals]);
+
+  const sharedEntries = useMemo(
+    () => Object.entries(shares).filter(([, rights]) => rights != null),
+    [shares],
+  );
+
+  const candidates = useMemo(() => {
+    const self = ownPrincipalId();
+    const q = search.trim().toLowerCase();
+    return principals
+      .filter((p) => p.id !== self && shares[p.id] == null)
+      .filter((p) =>
+        !q ||
+        p.name?.toLowerCase().includes(q) ||
+        p.email?.toLowerCase().includes(q) ||
+        p.description?.toLowerCase().includes(q))
+      .slice(0, 25);
+  }, [principals, shares, search]);
+
+  const applyShare = useCallback(
+    async (principalId: string, rights: FileNodeRights | null) => {
+      if (!node || savingId) return;
+      setSavingId(principalId);
+      try {
+        await setFileNodeShare(node.id, principalId, rights);
+        setShares((prev) => {
+          const next = { ...prev };
+          if (rights == null) delete next[principalId];
+          else next[principalId] = rights;
+          return next;
+        });
+        onChanged();
+      } catch (e) {
+        Alert.alert('Sharing failed', e instanceof Error ? e.message : String(e));
+      } finally {
+        setSavingId(null);
+      }
+    },
+    [node, savingId, onChanged],
+  );
+
+  if (!node) return null;
+  const Icon = isFolder(node) ? Folder : FileText;
+
+  const renderPrincipalLabel = (principalId: string) => {
+    const p = principalsById.get(principalId);
+    return (
+      <View style={styles.principalInfo}>
+        <Text style={styles.principalName} numberOfLines={1}>
+          {p?.description || p?.name || principalId}
+        </Text>
+        {p?.email ? (
+          <Text style={styles.principalEmail} numberOfLines={1}>
+            {p.email}
+          </Text>
+        ) : null}
+      </View>
+    );
+  };
+
+  return (
+    <Modal visible transparent animationType="slide" onRequestClose={onClose}>
+      <TouchableWithoutFeedback onPress={onClose}>
+        <View style={styles.backdrop}>
+          <TouchableWithoutFeedback>
+            <View style={styles.sheet}>
+              <View style={styles.titleRow}>
+                <Icon size={18} color={c.textMuted} />
+                <Text style={styles.title} numberOfLines={1}>
+                  Share “{node.name}”
+                </Text>
+              </View>
+              {isFolder(node) ? (
+                <Text style={styles.subtitle}>
+                  Sharing a folder shares everything inside it.
+                </Text>
+              ) : null}
+
+              <ScrollView
+                style={styles.scroll}
+                keyboardShouldPersistTaps="handled"
+              >
+                {sharedEntries.length > 0 ? (
+                  <View style={styles.section}>
+                    <Text style={styles.sectionLabel}>Shared with</Text>
+                    {sharedEntries.map(([principalId, rights]) => {
+                      const preset = detectPreset(rights);
+                      const busy = savingId === principalId;
+                      return (
+                        <View key={principalId} style={styles.shareRow}>
+                          {renderPrincipalLabel(principalId)}
+                          <View style={styles.roleChips}>
+                            {PRESET_ORDER.map((p) => (
+                              <Pressable
+                                key={p}
+                                onPress={() => void applyShare(principalId, FILE_PRESETS[p])}
+                                disabled={busy}
+                                style={[styles.chip, preset === p && styles.chipActive]}
+                              >
+                                <Text
+                                  style={[styles.chipText, preset === p && styles.chipTextActive]}
+                                >
+                                  {PRESET_LABELS[p]}
+                                </Text>
+                              </Pressable>
+                            ))}
+                            {preset === 'custom' ? (
+                              <Text style={styles.customLabel}>Custom</Text>
+                            ) : null}
+                          </View>
+                          {busy ? (
+                            <ActivityIndicator size="small" color={c.textMuted} />
+                          ) : (
+                            <Pressable
+                              onPress={() => void applyShare(principalId, null)}
+                              hitSlop={8}
+                              accessibilityLabel="Remove access"
+                            >
+                              <Trash2 size={18} color={c.error} />
+                            </Pressable>
+                          )}
+                        </View>
+                      );
+                    })}
+                  </View>
+                ) : (
+                  <View style={styles.emptyRow}>
+                    <Users size={18} color={c.textMuted} />
+                    <Text style={styles.emptyText}>Not shared with anyone yet</Text>
+                  </View>
+                )}
+
+                <View style={styles.section}>
+                  <Text style={styles.sectionLabel}>Add people</Text>
+                  <TextInput
+                    value={search}
+                    onChangeText={setSearch}
+                    placeholder="Search by name or email"
+                    placeholderTextColor={c.textMuted}
+                    style={styles.input}
+                    autoCapitalize="none"
+                    autoCorrect={false}
+                  />
+                  {loadingPrincipals ? (
+                    <ActivityIndicator
+                      size="small"
+                      color={c.textMuted}
+                      style={{ marginTop: spacing.sm }}
+                    />
+                  ) : candidates.length === 0 ? (
+                    <Text style={styles.noMatches}>
+                      {principals.length === 0 ? 'No other users found' : 'No matches'}
+                    </Text>
+                  ) : (
+                    candidates.map((p) => (
+                      <Pressable
+                        key={p.id}
+                        onPress={() => void applyShare(p.id, FILE_PRESETS.read)}
+                        disabled={savingId != null}
+                        style={({ pressed }) => [
+                          styles.candidateRow,
+                          pressed && { backgroundColor: c.surfaceHover },
+                        ]}
+                      >
+                        {renderPrincipalLabel(p.id)}
+                        {savingId === p.id ? (
+                          <ActivityIndicator size="small" color={c.textMuted} />
+                        ) : (
+                          <UserPlus size={18} color={c.primary} />
+                        )}
+                      </Pressable>
+                    ))
+                  )}
+                </View>
+              </ScrollView>
+
+              <Pressable onPress={onClose} style={styles.doneBtn}>
+                <Text style={styles.doneText}>Done</Text>
+              </Pressable>
+            </View>
+          </TouchableWithoutFeedback>
+        </View>
+      </TouchableWithoutFeedback>
+    </Modal>
+  );
+}
+
+function makeStyles(c: ThemePalette) {
+  return StyleSheet.create({
+    backdrop: {
+      flex: 1,
+      backgroundColor: 'rgba(0,0,0,0.5)',
+      justifyContent: 'flex-end',
+    },
+    sheet: {
+      backgroundColor: c.background,
+      borderTopLeftRadius: radius.lg,
+      borderTopRightRadius: radius.lg,
+      paddingTop: spacing.md,
+      paddingBottom: spacing.xxl,
+      paddingHorizontal: spacing.md,
+      maxHeight: '80%',
+    },
+    titleRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.sm,
+      paddingHorizontal: spacing.sm,
+    },
+    title: {
+      ...typography.h3,
+      color: c.text,
+      flexShrink: 1,
+    },
+    subtitle: {
+      fontSize: typography.caption.fontSize,
+      color: c.textMuted,
+      paddingHorizontal: spacing.sm,
+      marginTop: 2,
+    },
+    scroll: {
+      marginTop: spacing.sm,
+    },
+    section: {
+      marginTop: spacing.md,
+    },
+    sectionLabel: {
+      fontSize: typography.caption.fontSize,
+      fontWeight: '600' as const,
+      color: c.textMuted,
+      textTransform: 'uppercase' as const,
+      paddingHorizontal: spacing.sm,
+      marginBottom: spacing.xs,
+    },
+    shareRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.sm,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.sm,
+      borderBottomWidth: 1,
+      borderBottomColor: c.border,
+    },
+    principalInfo: {
+      flex: 1,
+      minWidth: 0,
+    },
+    principalName: {
+      fontSize: typography.body.fontSize,
+      color: c.text,
+    },
+    principalEmail: {
+      fontSize: typography.caption.fontSize,
+      color: c.textMuted,
+    },
+    roleChips: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.xs,
+    },
+    chip: {
+      paddingHorizontal: spacing.sm,
+      paddingVertical: 4,
+      borderRadius: radius.sm,
+      borderWidth: 1,
+      borderColor: c.border,
+    },
+    chipActive: {
+      backgroundColor: c.primaryBg,
+      borderColor: c.primary,
+    },
+    chipText: {
+      fontSize: typography.caption.fontSize,
+      color: c.textMuted,
+    },
+    chipTextActive: {
+      color: c.primary,
+      fontWeight: '600' as const,
+    },
+    customLabel: {
+      fontSize: typography.caption.fontSize,
+      color: c.textMuted,
+      fontStyle: 'italic' as const,
+    },
+    emptyRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.sm,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.md,
+    },
+    emptyText: {
+      fontSize: typography.body.fontSize,
+      color: c.textMuted,
+    },
+    input: {
+      borderWidth: 1,
+      borderColor: c.border,
+      borderRadius: radius.md,
+      paddingHorizontal: spacing.md,
+      paddingVertical: spacing.sm,
+      color: c.text,
+      fontSize: typography.body.fontSize,
+      backgroundColor: c.surface,
+      marginHorizontal: spacing.sm,
+    },
+    noMatches: {
+      fontSize: typography.caption.fontSize,
+      color: c.textMuted,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.sm,
+    },
+    candidateRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.sm,
+      paddingHorizontal: spacing.sm,
+      paddingVertical: spacing.sm,
+      borderRadius: radius.md,
+    },
+    doneBtn: {
+      marginTop: spacing.md,
+      alignSelf: 'stretch',
+      alignItems: 'center',
+      paddingVertical: spacing.sm,
+      borderRadius: radius.md,
+      backgroundColor: c.primary,
+    },
+    doneText: {
+      color: c.primaryForeground,
+      fontWeight: '600' as const,
+      fontSize: typography.body.fontSize,
+    },
+  });
+}

src/lib/__tests__/calendar-utils.test.ts

@@ -7,6 +7,9 @@ import {
   normalizeAllDayDuration,
   buildAllDayDuration,
   getCalendarColor,
+  getEventStartDate,
+  getEventEndDate,
+  timePattern,
   layoutOverlappingEvents,
   CALENDAR_COLOR_PALETTE,
 } from '../calendar-utils';
@@ -51,6 +54,32 @@ describe('parseLocalDateTime', () => {
   });
 });
 
+describe('getEventStartDate / getEventEndDate malformed utc fallback', () => {
+  // Mirrors webmail (#316): a malformed utcStart/utcEnd must fall back to the
+  // floating `start` + duration instead of producing an Invalid Date, which
+  // would silently drop the event from the day index and every view.
+  it('falls back to start when utcStart is unparseable', () => {
+    const d = getEventStartDate(ev({ utcStart: 'garbage' }));
+    expect(isNaN(d.getTime())).toBe(false);
+    expect(d.getHours()).toBe(9);
+  });
+
+  it('falls back to start + duration when utcEnd is unparseable', () => {
+    const end = getEventEndDate(ev({ utcEnd: 'garbage', duration: 'PT1H' }));
+    expect(isNaN(end.getTime())).toBe(false);
+    const start = getEventStartDate(ev({}));
+    expect(end.getTime() - start.getTime()).toBe(60 * 60 * 1000);
+  });
+});
+
+describe('timePattern', () => {
+  it('maps 12h to an am/pm pattern and 24h (or undefined) to HH:mm', () => {
+    expect(timePattern('12h')).toBe('h:mm a');
+    expect(timePattern('24h')).toBe('HH:mm');
+    expect(timePattern(undefined)).toBe('HH:mm');
+  });
+});
+
 describe('eventTimeRange', () => {
   it('returns start, end, allDay for a timed event with utcStart/utcEnd', () => {
     const range = eventTimeRange(ev({

src/lib/__tests__/recurrence-expansion.test.ts

@@ -174,3 +174,77 @@ describe('expandRecurringEvents - range filtering', () => {
     ]);
   });
 });
+
+describe('expandRecurringEvents - excludedRecurrenceRules', () => {
+  it('removes occurrences generated by excluded rules', () => {
+    const event = ev({
+      start: '2025-01-06T09:00:00',
+      recurrenceRules: [{ frequency: 'daily' }],
+      excludedRecurrenceRules: [{
+        frequency: 'weekly',
+        byDay: [{ day: 'tu' }],
+      }],
+    });
+    // Jan 6-12 2025: Mon-Sun, Tuesday Jan 7 excluded
+    const result = expandRecurringEvents([event], '2025-01-06T00:00:00', '2025-01-13T00:00:00');
+    const days = result.map((e) => e.start.substring(0, 10));
+    expect(days).not.toContain('2025-01-07');
+    expect(days).toContain('2025-01-06');
+    expect(days).toContain('2025-01-08');
+    expect(result).toHaveLength(6);
+  });
+});
+
+describe('expandRecurringEvents - long-running series', () => {
+  it('expands a daily series started years before the visible range', () => {
+    const event = ev({
+      start: '2022-01-03T09:00:00',
+      recurrenceRules: [{ frequency: 'daily' }],
+    });
+    const result = expandRecurringEvents([event], '2025-06-02T00:00:00', '2025-06-05T00:00:00');
+    expect(result.map((e) => e.start)).toEqual([
+      '2025-06-02T09:00:00',
+      '2025-06-03T09:00:00',
+      '2025-06-04T09:00:00',
+    ]);
+  });
+
+  it('expands a weekly series started years before the visible range', () => {
+    const event = ev({
+      start: '2020-01-06T09:00:00', // Monday
+      recurrenceRules: [{ frequency: 'weekly' }],
+    });
+    const result = expandRecurringEvents([event], '2025-06-01T00:00:00', '2025-06-30T00:00:00');
+    const days = result.map((e) => e.start.substring(0, 10));
+    expect(days).toEqual(['2025-06-02', '2025-06-09', '2025-06-16', '2025-06-23']);
+  });
+
+  it('still respects count for old series (no fast-forward shortcut)', () => {
+    const event = ev({
+      start: '2025-01-06T09:00:00',
+      recurrenceRules: [{ frequency: 'daily', count: 5 }],
+    });
+    // Range far after the 5 occurrences ran out
+    const result = expandRecurringEvents([event], '2025-06-01T00:00:00', '2025-06-30T00:00:00');
+    expect(result).toHaveLength(0);
+  });
+});
+
+describe('expandRecurringEvents - event timezone DST handling', () => {
+  it('keeps wall time across a DST transition in the event timezone', () => {
+    // America/New_York: EST (UTC-5) until 2025-03-09, EDT (UTC-4) after
+    const event = ev({
+      start: '2025-03-03T10:00:00',
+      timeZone: 'America/New_York',
+      utcStart: '2025-03-03T15:00:00Z',
+      utcEnd: '2025-03-03T16:00:00Z',
+      recurrenceRules: [{ frequency: 'weekly' }],
+    });
+    const result = expandRecurringEvents([event], '2025-03-03T00:00:00', '2025-03-17T00:00:00');
+    const utcStarts = result.map((e) => e.utcStart);
+    expect(utcStarts[0]).toBe('2025-03-03T15:00:00.000Z'); // EST: 10:00 -5
+    expect(utcStarts[1]).toBe('2025-03-10T14:00:00.000Z'); // EDT: 10:00 -4
+    const utcEnds = result.map((e) => e.utcEnd);
+    expect(utcEnds[1]).toBe('2025-03-10T15:00:00.000Z');
+  });
+});

src/lib/calendar-utils.ts

@@ -35,13 +35,20 @@ export function parseLocalDateTime(iso: string): Date {
 export function getEventStartDate(
   event: Pick<CalendarEvent, 'start' | 'utcStart' | 'showWithoutTime'>,
 ): Date {
-  const source = !event.showWithoutTime && event.utcStart ? event.utcStart : event.start;
-  return parseISO(source);
+  // Prefer utcStart for timed events but fall back to start if utcStart is
+  // missing or unparseable — a malformed utcStart used to surface as an
+  // Invalid Date that silently dropped the event from every view (#316).
+  if (!event.showWithoutTime && event.utcStart) {
+    const utc = parseISO(event.utcStart);
+    if (!isNaN(utc.getTime())) return utc;
+  }
+  return parseISO(event.start);
 }
 
 export function getEventEndDate(event: CalendarEvent): Date {
   if (!event.showWithoutTime && event.utcEnd) {
-    return parseISO(event.utcEnd);
+    const utc = parseISO(event.utcEnd);
+    if (!isNaN(utc.getTime())) return utc;
   }
   const start = getEventStartDate(event);
   if (!event.duration) return start;
@@ -57,6 +64,17 @@ export function getEventDisplayEndDate(event: CalendarEvent): Date {
   return subMilliseconds(end, 1);
 }
 
+// ─── Time-of-day formatting ──────────────────────────────
+// Maps the user's 12h/24h preference to a date-fns pattern, matching webmail
+// (event-card.tsx: `timeFormat === "12h" ? "h:mm a" : "HH:mm"`). Components
+// thread the `calendarTimeFormat` setting through so the calendar renders
+// times in the same format the webmail does.
+export type TimeFormat = '12h' | '24h';
+
+export function timePattern(timeFormat: TimeFormat | undefined): string {
+  return timeFormat === '12h' ? 'h:mm a' : 'HH:mm';
+}
+
 export interface EventTimeRange {
   start: Date;
   end: Date;
@@ -435,12 +453,63 @@ export function getEventColor(
   event: Pick<CalendarEvent, 'calendarIds' | 'color'>,
   calendars: Calendar[],
 ): string {
-  if (event.color) return event.color;
   const calendarId = Object.keys(event.calendarIds || {})[0];
   const cal = calendars.find((c) => c.id === calendarId);
+  // A local color override on a shared calendar wins over per-event colors,
+  // so the whole shared calendar paints uniformly in the viewer's chosen hue.
+  if (cal?.colorIsLocalOverride && cal.color) return cal.color;
+  if (event.color) return event.color;
   return getCalendarColor(cal);
 }
 
+// ─── Per-viewer colors for shared calendars (#345) ───────
+// Shared calendars are recolored locally only: the viewer usually can't write
+// the owner's calendar, and doing so would recolor it for everyone. Overrides
+// live in the settings store keyed by sharedCalendarColorKey().
+
+/**
+ * Stable key for a shared calendar's local color override. Built from the
+ * owning JMAP account + the calendar id so it stays unique across accounts.
+ */
+export function sharedCalendarColorKey(
+  cal: Pick<Calendar, 'id' | 'accountId'>,
+): string {
+  return `${cal.accountId ?? ''}|${cal.id}`;
+}
+
+/**
+ * Pick a random palette color not present in `usedColors`. Once every palette
+ * entry is taken, fall back to a random palette color (collisions are
+ * unavoidable past CALENDAR_PALETTE.length calendars).
+ */
+export function pickUnusedCalendarColor(usedColors: Iterable<string>): string {
+  const used = new Set<string>();
+  for (const c of usedColors) {
+    if (c) used.add(c.toLowerCase());
+  }
+  const available = CALENDAR_PALETTE.filter((c) => !used.has(c.toLowerCase()));
+  const pool = available.length > 0 ? available : CALENDAR_PALETTE;
+  return pool[Math.floor(Math.random() * pool.length)];
+}
+
+/**
+ * Apply each shared calendar's local color override (per-viewer recolor).
+ * The override replaces the calendar's color and wins over per-event colors
+ * via the `colorIsLocalOverride` flag (see getEventColor). Personal calendars
+ * are passed through untouched.
+ */
+export function applySharedCalendarColors(
+  calendars: Calendar[],
+  overrides: Record<string, string>,
+): Calendar[] {
+  return calendars.map((cal) => {
+    if (!cal.isShared) return cal;
+    const override = overrides[sharedCalendarColorKey(cal)];
+    if (!override) return cal;
+    return { ...cal, color: override, colorIsLocalOverride: true };
+  });
+}
+
 export function getPrimaryCalendarId(
   event: Pick<CalendarEvent, 'calendarIds'>,
 ): string | undefined {

src/lib/email-export.ts

@@ -89,13 +89,15 @@ export async function shareAttachment(
   name: string | undefined,
   type: string | undefined,
   email?: Email | null,
+  // Owning account for blobs shared by another principal (Files app).
+  accountId?: string,
 ): Promise<void> {
   const filename = email
     ? attachmentDownloadFilename(email, { name, type }, attachmentFileOptions())
     : safeAttachmentName(name, type);
   const mimeType = type || 'application/octet-stream';
   const dest = new File(Paths.cache, filename);
-  const url = getDownloadUrl(blobId, filename, mimeType);
+  const url = getDownloadUrl(blobId, filename, mimeType, accountId);
   const downloaded = await downloadInto(url, dest, Paths.cache);
   if (!(await Sharing.isAvailableAsync())) {
     throw new Error('Sharing is not available on this device');
@@ -116,13 +118,15 @@ export async function downloadAttachment(
   name: string | undefined,
   type: string | undefined,
   email?: Email | null,
+  // Owning account for blobs shared by another principal (Files app).
+  accountId?: string,
 ): Promise<void> {
   const filename = email
     ? attachmentDownloadFilename(email, { name, type }, attachmentFileOptions())
     : safeAttachmentName(name, type);
   const mimeType = type || 'application/octet-stream';
   const dest = new File(Paths.document, filename);
-  const url = getDownloadUrl(blobId, filename, mimeType);
+  const url = getDownloadUrl(blobId, filename, mimeType, accountId);
   const downloaded = await downloadInto(url, dest, Paths.document);
   if (!(await Sharing.isAvailableAsync())) {
     throw new Error('Sharing is not available on this device');

src/lib/recurrence-expansion.ts

@@ -11,7 +11,7 @@
  * on the client.
  */
 
-import { addDays, addMonths, addWeeks, addYears, format, parseISO } from 'date-fns';
+import { addDays, addMonths, addWeeks, addYears, differenceInCalendarDays, format, parseISO } from 'date-fns';
 import type { CalendarEvent, RecurrenceRule } from '../api/types';
 
 type NDay = { day: string; nthOfPeriod?: number };
@@ -60,6 +60,10 @@ export function expandRecurringEvents(
   return result;
 }
 
+function occurrenceDateKey(master: CalendarEvent, date: Date): string {
+  return master.showWithoutTime ? format(date, 'yyyy-MM-dd') : date.toISOString();
+}
+
 function expandEvent(
   master: CalendarEvent,
   rangeStart: Date,
@@ -73,13 +77,23 @@ function expandEvent(
   const occurrences: CalendarEvent[] = [];
   const seenDates = new Set<string>();
 
+  // RFC 8984 §4.3.3: occurrences produced by excludedRecurrenceRules
+  // (iCalendar EXRULE) are removed from the recurrence set.
+  const excludedDates = new Set<string>();
+  for (const exRule of master.excludedRecurrenceRules || []) {
+    // includeStartDate=false: "the series start is always an occurrence"
+    // applies to recurrence rules, not to exclusion rules.
+    for (const date of generateDates(eventStart, exRule, rangeStart, rangeEnd, false)) {
+      excludedDates.add(occurrenceDateKey(master, date));
+    }
+  }
+
   for (const rule of rules) {
     const dates = generateDates(eventStart, rule, rangeStart, rangeEnd);
     for (const date of dates) {
-      const dateKey = master.showWithoutTime
-        ? format(date, 'yyyy-MM-dd')
-        : date.toISOString();
+      const dateKey = occurrenceDateKey(master, date);
 
+      if (excludedDates.has(dateKey)) continue;
       if (seenDates.has(dateKey)) continue;
       seenDates.add(dateKey);
 
@@ -104,9 +118,9 @@ function expandEvent(
     if (isNaN(overrideDate.getTime())) continue;
     if (overrideDate < rangeStart || overrideDate >= rangeEnd) continue;
 
-    const dateKey = master.showWithoutTime
-      ? format(overrideDate, 'yyyy-MM-dd')
-      : overrideDate.toISOString();
+    // Overrides take precedence over excludedRecurrenceRules (they re-add
+    // a concrete instance), so only dedupe against already-generated dates.
+    const dateKey = occurrenceDateKey(master, overrideDate);
     if (seenDates.has(dateKey)) continue;
     seenDates.add(dateKey);
 
@@ -116,6 +130,65 @@ function expandEvent(
   return occurrences;
 }
 
+// Cache Intl formatters per IANA timezone id — constructing them is expensive
+// and expansion runs over hundreds of occurrences. `null` marks ids the
+// runtime rejected so we don't retry them.
+const tzFormatterCache = new Map<string, Intl.DateTimeFormat | null>();
+
+function getTzFormatter(timeZone: string): Intl.DateTimeFormat | null {
+  let formatter = tzFormatterCache.get(timeZone);
+  if (formatter === undefined) {
+    try {
+      formatter = new Intl.DateTimeFormat('en-CA', {
+        timeZone,
+        year: 'numeric',
+        month: '2-digit',
+        day: '2-digit',
+        hour: '2-digit',
+        minute: '2-digit',
+        second: '2-digit',
+        hour12: false,
+      });
+    } catch {
+      formatter = null;
+    }
+    tzFormatterCache.set(timeZone, formatter);
+  }
+  return formatter;
+}
+
+/** The wall-clock reading of `instant` in the formatter's zone, re-encoded as a UTC timestamp. */
+function wallClockAsUtcTimestamp(formatter: Intl.DateTimeFormat, instant: number): number {
+  const map: Record<string, string> = {};
+  for (const part of formatter.formatToParts(new Date(instant))) {
+    if (part.type !== 'literal') map[part.type] = part.value;
+  }
+  const hour = map.hour === '24' ? 0 : Number(map.hour);
+  return Date.UTC(
+    Number(map.year), Number(map.month) - 1, Number(map.day),
+    hour, Number(map.minute), Number(map.second),
+  );
+}
+
+/**
+ * Interpret the wall-clock fields of `wall` as a local time in `timeZone`
+ * and return the corresponding UTC instant. Two fixup iterations converge
+ * for all real offsets, including across DST transitions.
+ */
+function zonedWallTimeToUtc(wall: Date, timeZone: string): Date | null {
+  const formatter = getTzFormatter(timeZone);
+  if (!formatter) return null;
+  const wallAsUtc = Date.UTC(
+    wall.getFullYear(), wall.getMonth(), wall.getDate(),
+    wall.getHours(), wall.getMinutes(), wall.getSeconds(),
+  );
+  let guess = wallAsUtc;
+  for (let i = 0; i < 2; i++) {
+    guess = wallAsUtc - (wallClockAsUtcTimestamp(formatter, guess) - guess);
+  }
+  return new Date(guess);
+}
+
 function createOccurrence(
   master: CalendarEvent,
   date: Date,
@@ -130,16 +203,33 @@ function createOccurrence(
   // getEventEndDate return the occurrence times rather than the master's.
   let utcStart: string | undefined;
   let utcEnd: string | undefined;
-  if (!master.showWithoutTime && master.utcStart && master.start) {
-    const masterLocal = parseISO(master.start);
-    const masterUtc = parseISO(master.utcStart);
-    const offsetMs = masterUtc.getTime() - masterLocal.getTime();
-    utcStart = new Date(date.getTime() + offsetMs).toISOString();
+  if (!master.showWithoutTime) {
+    let durationMs: number | null = null;
+    if (master.utcStart && master.utcEnd) {
+      const ms = parseISO(master.utcEnd).getTime() - parseISO(master.utcStart).getTime();
+      if (!isNaN(ms)) durationMs = ms;
+    }
 
-    if (master.utcEnd) {
-      const masterUtcEnd = parseISO(master.utcEnd);
-      const durationMs = masterUtcEnd.getTime() - masterUtc.getTime();
-      utcEnd = new Date(date.getTime() + offsetMs + durationMs).toISOString();
+    // Convert the occurrence's wall time using the event's own timezone, so
+    // occurrences on the other side of a DST transition in that zone keep
+    // their wall time. Reusing the master's fixed UTC offset (the fallback
+    // below) would shift them by the DST delta.
+    const zoned = master.timeZone ? zonedWallTimeToUtc(date, master.timeZone) : null;
+    if (zoned) {
+      utcStart = zoned.toISOString();
+      if (durationMs !== null) {
+        utcEnd = new Date(zoned.getTime() + durationMs).toISOString();
+      }
+    } else if (master.utcStart && master.start) {
+      // Floating events (or an unrecognized timezone id): keep the master's
+      // offset, which by definition doesn't vary.
+      const masterLocal = parseISO(master.start);
+      const masterUtc = parseISO(master.utcStart);
+      const offsetMs = masterUtc.getTime() - masterLocal.getTime();
+      utcStart = new Date(date.getTime() + offsetMs).toISOString();
+      if (durationMs !== null) {
+        utcEnd = new Date(date.getTime() + offsetMs + durationMs).toISOString();
+      }
     }
   }
 
@@ -207,6 +297,7 @@ function generateDates(
   rawRule: RecurrenceRule,
   rangeStart: Date,
   rangeEnd: Date,
+  includeStartDate = true,
 ): Date[] {
   const rule = addImplicitByX(rawRule, eventStart);
   const dates: Date[] = [];
@@ -214,21 +305,34 @@ function generateDates(
   const countLimit = rule.count || Infinity;
   const until = rule.until ? parseISO(rule.until) : null;
   let totalCount = 0;
-  let current = new Date(eventStart);
+  // Without a `count` limit we can jump straight to the period containing
+  // the visible range. With one, every occurrence since the series start
+  // must be generated so it counts against `count`.
+  let current = rule.count
+    ? new Date(eventStart)
+    : fastForwardToRange(eventStart, rule.frequency, interval, rangeStart);
 
   const maxIterations = 2000;
+  // Cap on *emitted* (in-range) dates. This must not count occurrences
+  // before rangeStart, otherwise a series started long ago (e.g. a daily
+  // event from two years back) exhausts the budget before reaching the
+  // visible range and silently renders nothing.
   const maxOccurrences = 500;
   let iterations = 0;
 
   while (iterations++ < maxIterations) {
-    if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
+    if (totalCount >= countLimit || dates.length >= maxOccurrences) break;
     if (until && current > until) break;
-    if (
-      current >= rangeEnd
-      && rule.frequency !== 'yearly'
-      && rule.frequency !== 'monthly'
-      && rule.frequency !== 'weekly'
-    ) break;
+    // Stop once no candidate in this or a later period can fall before
+    // rangeEnd. Monthly/yearly candidates may precede the period anchor
+    // within the same month/year, so floor the anchor before comparing.
+    if (rule.frequency === 'monthly') {
+      if (new Date(current.getFullYear(), current.getMonth(), 1) >= rangeEnd) break;
+    } else if (rule.frequency === 'yearly') {
+      if (new Date(current.getFullYear(), 0, 1) >= rangeEnd) break;
+    } else if (current >= rangeEnd) {
+      break;
+    }
 
     const candidates = generateCandidatesForPeriod(current, rule, eventStart);
 
@@ -238,7 +342,7 @@ function generateDates(
 
     for (const d of filtered) {
       if (until && d > until) break;
-      if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
+      if (totalCount >= countLimit || dates.length >= maxOccurrences) break;
 
       // Spec rule 4: eliminate dates before event start
       if (d < eventStart) continue;
@@ -250,7 +354,7 @@ function generateDates(
       if (d >= rangeEnd) break;
     }
 
-    if (totalCount >= countLimit || totalCount >= maxOccurrences) break;
+    if (totalCount >= countLimit || dates.length >= maxOccurrences) break;
 
     current = advancePeriod(current, rule.frequency, interval);
     if (current <= eventStart && iterations === 1) {
@@ -259,7 +363,7 @@ function generateDates(
   }
 
   // Spec rule 1: the start date-time is ALWAYS the first occurrence.
-  if (dates.length > 0 && dates[0].getTime() !== eventStart.getTime()) {
+  if (includeStartDate && dates.length > 0 && dates[0].getTime() !== eventStart.getTime()) {
     if (eventStart >= rangeStart && eventStart < rangeEnd) {
       if (!dates.some((d) => d.getTime() === eventStart.getTime())) {
         dates.unshift(eventStart);
@@ -505,6 +609,66 @@ function advancePeriod(
   }
 }
 
+// ─── Fast-forward to the visible range ───────────────────
+// Jump to the period just before the visible range in O(1), so long-running
+// series don't burn the iteration budget on years of out-of-range periods.
+// Only valid for rules without `count` (counted rules must enumerate every
+// occurrence from the series start).
+function fastForwardToRange(
+  eventStart: Date,
+  frequency: RecurrenceRule['frequency'],
+  interval: number,
+  rangeStart: Date,
+): Date {
+  if (eventStart >= rangeStart) return new Date(eventStart);
+
+  let periods: number;
+  switch (frequency) {
+    case 'secondly':
+      periods = Math.floor((rangeStart.getTime() - eventStart.getTime()) / (1000 * interval));
+      break;
+    case 'minutely':
+      periods = Math.floor((rangeStart.getTime() - eventStart.getTime()) / (60000 * interval));
+      break;
+    case 'hourly':
+      periods = Math.floor((rangeStart.getTime() - eventStart.getTime()) / (3600000 * interval));
+      break;
+    case 'daily':
+      periods = Math.floor(differenceInCalendarDays(rangeStart, eventStart) / interval);
+      break;
+    case 'weekly':
+      periods = Math.floor(differenceInCalendarDays(rangeStart, eventStart) / (7 * interval));
+      break;
+    case 'monthly': {
+      const months = (rangeStart.getFullYear() - eventStart.getFullYear()) * 12
+        + (rangeStart.getMonth() - eventStart.getMonth());
+      periods = Math.floor(months / interval);
+      break;
+    }
+    case 'yearly':
+      periods = Math.floor((rangeStart.getFullYear() - eventStart.getFullYear()) / interval);
+      break;
+    default:
+      return new Date(eventStart);
+  }
+
+  // Land one full period early so candidates inside the boundary period
+  // (which can precede the period anchor) are still generated.
+  periods = Math.max(0, periods - 1);
+  if (periods === 0) return new Date(eventStart);
+
+  switch (frequency) {
+    case 'secondly': return new Date(eventStart.getTime() + periods * interval * 1000);
+    case 'minutely': return new Date(eventStart.getTime() + periods * interval * 60000);
+    case 'hourly': return new Date(eventStart.getTime() + periods * interval * 3600000);
+    case 'daily': return addDays(eventStart, periods * interval);
+    case 'weekly': return addWeeks(eventStart, periods * interval);
+    case 'monthly': return addMonths(eventStart, periods * interval);
+    case 'yearly': return addYears(eventStart, periods * interval);
+    default: return new Date(eventStart);
+  }
+}
+
 function expandByDayInMonth(
   year: number,
   month: number,

src/lib/recurrence.ts

@@ -0,0 +1,246 @@
+/**
+ * Custom recurrence rule helpers for the event editor. Mobile port of
+ * webmail's components/calendar/recurrence-editor.tsx logic (rule detection,
+ * construction, and the human-readable summary).
+ */
+
+import { format } from 'date-fns';
+import type { RecurrenceRule } from '../api/types';
+
+export type EditorFrequency = 'daily' | 'weekly' | 'monthly' | 'yearly';
+export type MonthlyMode = 'day' | 'nth';
+export type EndsMode = 'never' | 'on' | 'after';
+
+export const EDITOR_FREQUENCIES: EditorFrequency[] = ['daily', 'weekly', 'monthly', 'yearly'];
+
+// JSCalendar weekday ids in display order (week starts Monday, matching the
+// firstDayOfWeek the built rules declare).
+export const WEEKDAYS: string[] = ['mo', 'tu', 'we', 'th', 'fr', 'sa', 'su'];
+const DAY_TO_REF_DATE: Record<string, number> = { mo: 1, tu: 2, we: 3, th: 4, fr: 5, sa: 6, su: 7 };
+export const INDEX_TO_DAY = ['su', 'mo', 'tu', 'we', 'th', 'fr', 'sa'];
+
+export const UNIT_LABELS: Record<EditorFrequency, string> = {
+  daily: 'days',
+  weekly: 'weeks',
+  monthly: 'months',
+  yearly: 'years',
+};
+
+// 2024-01-01 is a Monday — used to render weekday names via date-fns.
+export function weekdayName(day: string, style: 'long' | 'short' = 'long'): string {
+  const ref = new Date(2024, 0, DAY_TO_REF_DATE[day] ?? 1);
+  return format(ref, style === 'long' ? 'EEEE' : 'EEE');
+}
+
+export function monthName(month: number): string {
+  return format(new Date(2024, month - 1, 1), 'LLLL');
+}
+
+const NTH_LABELS: Record<number, string> = {
+  1: 'first',
+  2: 'second',
+  3: 'third',
+  4: 'fourth',
+  [-1]: 'last',
+};
+
+export function nthLabel(nth: number): string {
+  return NTH_LABELS[nth] ?? String(nth);
+}
+
+export function capitalize(s: string): string {
+  return s.charAt(0).toUpperCase() + s.slice(1);
+}
+
+/**
+ * Extract an "nth weekday" pattern from a rule, accepting both the
+ * byDay+nthOfPeriod encoding and the byDay+bySetPosition encoding.
+ */
+export function getNthDay(rule: RecurrenceRule): { day: string; nth: number } | null {
+  if (rule.byDay?.length === 1) {
+    const nd = rule.byDay[0];
+    if (nd.nthOfPeriod) return { day: nd.day, nth: nd.nthOfPeriod };
+    if (rule.bySetPosition?.length === 1) return { day: nd.day, nth: rule.bySetPosition[0] };
+  }
+  return null;
+}
+
+/**
+ * True when the rule is exactly what the plain Daily/Weekly/Monthly/Yearly
+ * dropdown presets produce, i.e. it needs no custom editor to represent.
+ */
+export function isSimpleRecurrenceRule(rule: RecurrenceRule): boolean {
+  return (
+    (EDITOR_FREQUENCIES as string[]).includes(rule.frequency) &&
+    (!rule.interval || rule.interval === 1) &&
+    !rule.byDay?.length &&
+    !rule.byMonthDay?.length &&
+    !rule.byMonth?.length &&
+    !rule.byYearDay?.length &&
+    !rule.byWeekNo?.length &&
+    !rule.bySetPosition?.length &&
+    !rule.count &&
+    !rule.until
+  );
+}
+
+/**
+ * Human-readable summary of a recurrence rule, e.g.
+ * "Every 2 months on the third Thursday · 12 occurrences".
+ * Returns null for frequencies the UI cannot describe (hourly etc.).
+ */
+export function buildRecurrenceSummary(rule: RecurrenceRule): string | null {
+  const interval = rule.interval || 1;
+  let base: string;
+  switch (rule.frequency) {
+    case 'daily':
+      base = interval > 1 ? `Every ${interval} days` : 'Daily';
+      break;
+    case 'weekly':
+      base = interval > 1 ? `Every ${interval} weeks` : 'Weekly';
+      break;
+    case 'monthly':
+      base = interval > 1 ? `Every ${interval} months` : 'Monthly';
+      break;
+    case 'yearly':
+      base = interval > 1 ? `Every ${interval} years` : 'Yearly';
+      break;
+    default:
+      return null;
+  }
+
+  const parts = [base];
+
+  if (rule.frequency === 'weekly' && rule.byDay?.length) {
+    const days = rule.byDay
+      .filter((d) => WEEKDAYS.includes(d.day))
+      .sort((a, b) => WEEKDAYS.indexOf(a.day) - WEEKDAYS.indexOf(b.day))
+      .map((d) => weekdayName(d.day, 'short'))
+      .join(', ');
+    if (days) parts.push(`on ${days}`);
+  }
+
+  if (rule.frequency === 'monthly' || rule.frequency === 'yearly') {
+    if (rule.frequency === 'yearly' && rule.byMonth?.length) {
+      const m = parseInt(rule.byMonth[0], 10);
+      if (m >= 1 && m <= 12) parts.push(`in ${monthName(m)}`);
+    }
+    const nthDay = getNthDay(rule);
+    if (nthDay) {
+      parts.push(`on the ${nthLabel(nthDay.nth)} ${weekdayName(nthDay.day)}`);
+    } else if (rule.byMonthDay?.length) {
+      parts.push(`on day ${rule.byMonthDay[0]}`);
+    }
+  }
+
+  let summary = parts.join(' ');
+  if (rule.count) {
+    summary += ` · ${rule.count} ${rule.count === 1 ? 'occurrence' : 'occurrences'}`;
+  } else if (rule.until) {
+    const d = new Date(rule.until);
+    if (!isNaN(d.getTime())) {
+      summary += ` · until ${format(d, 'MMM d, yyyy')}`;
+    }
+  }
+  return summary;
+}
+
+export interface RecurrenceEditorValue {
+  frequency: EditorFrequency;
+  interval: number;
+  weekDays: string[];
+  monthlyMode: MonthlyMode;
+  monthDay: number;
+  nth: number;
+  nthDay: string;
+  month: number;
+  endsMode: EndsMode;
+  untilDate: string; // yyyy-MM-dd
+  count: number;
+}
+
+/** Build the editor's initial state from an existing rule (or defaults). */
+export function editorValueFromRule(
+  rule: RecurrenceRule | null,
+  eventStart: Date,
+): RecurrenceEditorValue {
+  const startDay = INDEX_TO_DAY[eventStart.getDay()];
+  const nthDayInfo = rule ? getNthDay(rule) : null;
+
+  const weekDays = (() => {
+    if (rule?.frequency === 'weekly' && rule.byDay?.length) {
+      const days = rule.byDay.map((d) => d.day).filter((d) => WEEKDAYS.includes(d));
+      if (days.length) return days;
+    }
+    return [startDay];
+  })();
+
+  const monthFromRule = rule?.byMonth?.length ? parseInt(rule.byMonth[0], 10) : NaN;
+  const untilFromRule = (() => {
+    if (rule?.until) {
+      const d = new Date(rule.until);
+      if (!isNaN(d.getTime())) return format(d, 'yyyy-MM-dd');
+    }
+    const inAYear = new Date(eventStart);
+    inAYear.setFullYear(inAYear.getFullYear() + 1);
+    return format(inAYear, 'yyyy-MM-dd');
+  })();
+
+  return {
+    frequency: rule && (EDITOR_FREQUENCIES as string[]).includes(rule.frequency)
+      ? (rule.frequency as EditorFrequency)
+      : 'weekly',
+    interval: rule?.interval || 1,
+    weekDays,
+    monthlyMode: nthDayInfo ? 'nth' : 'day',
+    monthDay: rule?.byMonthDay?.[0] && rule.byMonthDay[0] >= 1 && rule.byMonthDay[0] <= 31
+      ? rule.byMonthDay[0]
+      : eventStart.getDate(),
+    nth: nthDayInfo && (nthDayInfo.nth === -1 || (nthDayInfo.nth >= 1 && nthDayInfo.nth <= 4))
+      ? nthDayInfo.nth
+      : Math.min(4, Math.floor((eventStart.getDate() - 1) / 7) + 1),
+    nthDay: nthDayInfo && WEEKDAYS.includes(nthDayInfo.day) ? nthDayInfo.day : startDay,
+    month: monthFromRule >= 1 && monthFromRule <= 12 ? monthFromRule : eventStart.getMonth() + 1,
+    endsMode: rule?.count ? 'after' : rule?.until ? 'on' : 'never',
+    untilDate: untilFromRule,
+    count: rule?.count ?? 12,
+  };
+}
+
+/** Build the JSCalendar rule the editor state describes. */
+export function buildRuleFromEditorValue(
+  value: RecurrenceEditorValue,
+  eventStart: Date,
+): RecurrenceRule {
+  const startDay = INDEX_TO_DAY[eventStart.getDay()];
+  const built: RecurrenceRule = {
+    '@type': 'RecurrenceRule',
+    frequency: value.frequency,
+    interval: Math.max(1, value.interval),
+    rscale: 'gregorian',
+    skip: 'omit',
+    firstDayOfWeek: 'mo',
+  };
+
+  if (value.endsMode === 'after') {
+    built.count = Math.max(1, value.count);
+  } else if (value.endsMode === 'on' && value.untilDate) {
+    built.until = `${value.untilDate}T23:59:59`;
+  }
+
+  if (value.frequency === 'weekly') {
+    const days = value.weekDays.length ? value.weekDays : [startDay];
+    built.byDay = WEEKDAYS.filter((d) => days.includes(d)).map((day) => ({ day }));
+  } else if (value.frequency === 'monthly' || value.frequency === 'yearly') {
+    if (value.monthlyMode === 'nth') {
+      built.byDay = [{ day: value.nthDay, nthOfPeriod: value.nth }];
+    } else {
+      built.byMonthDay = [Math.min(31, Math.max(1, value.monthDay))];
+    }
+    if (value.frequency === 'yearly') {
+      built.byMonth = [String(value.month)];
+    }
+  }
+
+  return built;
+}

src/screens/CalendarScreen.tsx

@@ -52,9 +52,13 @@ import { TasksSheet } from '../components/calendar/TasksSheet';
 import { ICalImportSheet } from '../components/calendar/ICalImportSheet';
 import { ICalSubscriptionSheet } from '../components/calendar/ICalSubscriptionSheet';
 import {
+  applySharedCalendarColors,
   buildEventDayIndex,
   eventsOnDayFromIndex,
+  pickUnusedCalendarColor,
+  sharedCalendarColorKey,
   type EventDayIndex,
+  type TimeFormat,
 } from '../lib/calendar-utils';
 import { buildReplyTo } from '../lib/calendar-invitation';
 import { generateBirthdayEvents, createBirthdayCalendar, BIRTHDAY_CALENDAR_ID } from '../lib/birthday-calendar';
@@ -117,6 +121,9 @@ export default function CalendarScreen() {
   const calendarTimeFormat = useSettingsStore((s) => s.calendarTimeFormat);
   const showBirthdayCalendar = useSettingsStore((s) => s.showBirthdayCalendar);
   const enableCalendarTasks = useSettingsStore((s) => s.enableCalendarTasks);
+  const sharedCalendarColors = useSettingsStore((s) => s.sharedCalendarColors);
+  const setSharedCalendarColor = useSettingsStore((s) => s.setSharedCalendarColor);
+  const removeSharedCalendarColor = useSettingsStore((s) => s.removeSharedCalendarColor);
   const contacts = useContactsStore((s) => s.contacts);
 
   const [currentDate, setCurrentDate] = React.useState(new Date());
@@ -154,6 +161,7 @@ export default function CalendarScreen() {
   const toggleTaskComplete = useCalendarStore((s) => s.toggleTaskComplete);
   const deleteTask = useCalendarStore((s) => s.deleteTask);
   const toggleCalendarVisibility = useCalendarStore((s) => s.toggleCalendarVisibility);
+  const setDefaultCalendar = useCalendarStore((s) => s.setDefaultCalendar);
   const storeCalendars = useCalendarStore((s) => s.calendars);
   const hiddenCalendarIds = useCalendarStore((s) => s.hiddenCalendarIds);
   const loading = useCalendarStore((s) => s.loading);
@@ -169,9 +177,41 @@ export default function CalendarScreen() {
     return generateBirthdayEvents(contacts, after.toISOString(), before.toISOString());
   }, [showBirthdayCalendar, contacts, viewMode, currentDate, calendarFirstDayOfWeek]);
 
+  // Per-viewer recolor (#345): shared calendars get the viewer's local color
+  // override applied before anything renders. Personal calendars pass through.
+  const displayCalendars = React.useMemo(
+    () => applySharedCalendarColors(storeCalendars, sharedCalendarColors),
+    [storeCalendars, sharedCalendarColors],
+  );
+
+  // Auto-assign a random, not-yet-used palette color to any freshly shared
+  // calendar so multiple shared calendars don't collide on one color. Runs
+  // once per calendar (guarded by the presence of an existing key), and the
+  // user can still overwrite it from the sidebar.
+  React.useEffect(() => {
+    const missing = storeCalendars.filter(
+      (cal) => cal.isShared && !sharedCalendarColors[sharedCalendarColorKey(cal)],
+    );
+    if (missing.length === 0) return;
+    // Seed "used" with personal calendar colors plus already-assigned shared
+    // overrides so the picks stay distinct from what's already on screen.
+    const used = new Set<string>();
+    for (const cal of storeCalendars) {
+      if (!cal.isShared && cal.color) used.add(cal.color.toLowerCase());
+    }
+    for (const color of Object.values(sharedCalendarColors)) {
+      if (color) used.add(color.toLowerCase());
+    }
+    for (const cal of missing) {
+      const color = pickUnusedCalendarColor(used);
+      used.add(color.toLowerCase());
+      setSharedCalendarColor(sharedCalendarColorKey(cal), color);
+    }
+  }, [storeCalendars, sharedCalendarColors, setSharedCalendarColor]);
+
   const allCalendars = React.useMemo(
-    () => (showBirthdayCalendar ? [...storeCalendars, createBirthdayCalendar()] : storeCalendars),
-    [storeCalendars, showBirthdayCalendar],
+    () => (showBirthdayCalendar ? [...displayCalendars, createBirthdayCalendar()] : displayCalendars),
+    [displayCalendars, showBirthdayCalendar],
   );
   const allEvents = React.useMemo(
     () => (birthdayEvents.length > 0 ? [...storeEvents, ...birthdayEvents] : storeEvents),
@@ -252,25 +292,34 @@ export default function CalendarScreen() {
     [],
   );
 
+  // A recurring series member is a master (has recurrenceRules) or an expanded
+  // occurrence (has recurrenceId) — those get the this/all scope dialog. Note:
+  // we must NOT key off originalId here, since shared/group events now carry it
+  // for id-namespacing even when they aren't recurring.
+  const isRecurringSeriesMember = React.useCallback(
+    (event: CalendarEvent) => !!event.recurrenceRules?.length || !!event.recurrenceId,
+    [],
+  );
+
   const handleEditFromDetail = React.useCallback((event: CalendarEvent) => {
     if (isReadOnlyEvent(event)) { setDetailEvent(null); return; }
     setDetailEvent(null);
-    if (event.recurrenceRules?.length || event.originalId) {
+    if (isRecurringSeriesMember(event)) {
       setPendingAction({ kind: 'edit', event });
     } else {
       openEditDirect(event);
     }
-  }, [openEditDirect, isReadOnlyEvent]);
+  }, [openEditDirect, isReadOnlyEvent, isRecurringSeriesMember]);
 
   const handleDeleteFromDetail = React.useCallback((event: CalendarEvent) => {
     if (isReadOnlyEvent(event)) { setDetailEvent(null); return; }
     setDetailEvent(null);
-    if (event.recurrenceRules?.length || event.originalId) {
+    if (isRecurringSeriesMember(event)) {
       setPendingAction({ kind: 'delete', event });
     } else {
       void deleteEvent(event.id);
     }
-  }, [deleteEvent, isReadOnlyEvent]);
+  }, [deleteEvent, isReadOnlyEvent, isRecurringSeriesMember]);
 
   const handleScopeSelect = React.useCallback(
     async (scope: RecurrenceEditScope) => {
@@ -420,6 +469,7 @@ export default function CalendarScreen() {
             events={events}
             eventsByDay={eventsByDay}
             calendars={calendars}
+            timeFormat={calendarTimeFormat}
             onSelectEvent={setDetailEvent}
           />
         )}
@@ -436,6 +486,7 @@ export default function CalendarScreen() {
               date={selectedDate}
               eventsByDay={eventsByDay}
               calendars={calendars}
+              timeFormat={calendarTimeFormat}
               onSelectEvent={setDetailEvent}
               refreshing={refreshing}
               onRefresh={onRefresh}
@@ -447,6 +498,7 @@ export default function CalendarScreen() {
       <EventDetailSheet
         event={detailEvent}
         calendars={calendars}
+        timeFormat={calendarTimeFormat}
         onClose={() => setDetailEvent(null)}
         onEdit={handleEditFromDetail}
         onDelete={handleDeleteFromDetail}
@@ -491,6 +543,13 @@ export default function CalendarScreen() {
         onClose={() => setSidebarVisible(false)}
         onImport={() => { setSidebarVisible(false); setImportVisible(true); }}
         onManageSubscriptions={() => { setSidebarVisible(false); setSubscriptionsVisible(true); }}
+        onSetDefault={(cal) => { void setDefaultCalendar(cal.id); }}
+        onSetColor={(cal, color) => setSharedCalendarColor(sharedCalendarColorKey(cal), color)}
+        onResetColor={(cal) => {
+          // Drop the local override; the auto-assign effect picks a fresh
+          // unused color (so it never reverts to a collision).
+          removeSharedCalendarColor(sharedCalendarColorKey(cal));
+        }}
       />
 
       <TasksSheet
@@ -505,7 +564,9 @@ export default function CalendarScreen() {
 
       <ICalImportSheet
         visible={importVisible}
-        calendars={storeCalendars}
+        // Import batch-creates against the primary account, so only offer the
+        // user's own calendars as targets.
+        calendars={displayCalendars.filter((cal) => !cal.isShared)}
         onClose={() => setImportVisible(false)}
         onImport={importEvents}
       />
@@ -522,6 +583,7 @@ function DayEventList({
   date,
   eventsByDay,
   calendars,
+  timeFormat,
   onSelectEvent,
   refreshing,
   onRefresh,
@@ -529,6 +591,7 @@ function DayEventList({
   date: Date;
   eventsByDay: EventDayIndex;
   calendars: Calendar[];
+  timeFormat?: TimeFormat;
   onSelectEvent?: (event: CalendarEvent) => void;
   refreshing: boolean;
   onRefresh: () => void;
@@ -565,6 +628,7 @@ function DayEventList({
           key={event.id}
           event={event}
           calendars={calendars}
+          timeFormat={timeFormat}
           onPress={onSelectEvent}
         />
       ))}

src/screens/EmailThreadScreen.tsx

@@ -1,8 +1,9 @@
 import React from 'react';
 import {
   View, Text, StyleSheet, ScrollView, Pressable, ActivityIndicator,
-  Modal, useWindowDimensions, Animated, Easing, Alert, PanResponder,
+  Modal, useWindowDimensions, Animated, Easing, Alert, FlatList,
 } from 'react-native';
+import type { NativeSyntheticEvent, NativeScrollEvent } from 'react-native';
 import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context';
 import type { NativeStackScreenProps } from '@react-navigation/native-stack';
 import {
@@ -35,8 +36,13 @@ type Props = NativeStackScreenProps<RootStackParamList, 'EmailThread'>;
 
 function formatHeaderDate(iso: string): string {
   const d = new Date(iso);
-  return d.toLocaleString(undefined, {
+  return d.toLocaleDateString(undefined, {
     weekday: 'short', year: 'numeric', month: 'short', day: 'numeric',
+  });
+}
+
+function formatHeaderTime(iso: string): string {
+  return new Date(iso).toLocaleTimeString(undefined, {
     hour: '2-digit', minute: '2-digit',
   });
 }
@@ -99,103 +105,65 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
     [activeEmailId, cacheVersion, detailCache],
   );
 
-  // --- Swipe / slide navigation between adjacent emails -------------------
-  // A three-pane pager: [prev | current | next] are laid out in a single row of
-  // width 3×screen and kept mounted side by side. `drag` translates the whole
-  // row so the neighbour's real content follows the finger — no blank gap and
-  // no late content-swap. At rest the row is shifted left by one screen so the
-  // middle (current) pane sits on screen. After a settled swipe we re-point
-  // `activeEmailId` at the neighbour and reset `drag` to 0 in the same commit;
-  // because the landed pane already shows that exact message, the recentre is
-  // seamless. Refs keep the (memoised once) PanResponder reading the latest
-  // neighbours / dimensions without being recreated every render.
-  const drag = React.useRef(new Animated.Value(0)).current;
-  const animatingRef = React.useRef(false);
-  const pendingRecentreRef = React.useRef(false);
-  const prevEmailRef = React.useRef(prevEmail);
-  const nextEmailRef = React.useRef(nextEmail);
-  const windowWidthRef = React.useRef(windowWidth);
-  prevEmailRef.current = prevEmail;
-  nextEmailRef.current = nextEmail;
-  windowWidthRef.current = windowWidth;
+  // --- Pager -------------------------------------------------------------
+  // The pager is a horizontal, page-snapping FlatList over the mailbox's
+  // `emails`. Native scroll provides the swipe + snap (and plays nicely with
+  // each pane's vertical body scroll); Prev/Next scroll programmatically. When
+  // scrolling settles, the centred page's id becomes `activeEmailId`, which is
+  // what the toolbar and action handlers operate on.
+  const listRef = React.useRef<FlatList<Email>>(null);
+  // The page to open on mount — the entry point arrives as a route param, so
+  // capture its index once.
+  const initialIndexRef = React.useRef(
+    Math.max(0, emails.findIndex((e) => e.id === route.params.emailId)),
+  );
 
-  const switchEmail = React.useCallback((direction: 'prev' | 'next') => {
-    const target = direction === 'next' ? nextEmailRef.current : prevEmailRef.current;
-    if (!target || animatingRef.current) return;
-    animatingRef.current = true;
-    const w = windowWidthRef.current;
-    // Bring the neighbour pane to centre: next sits to the right (slide row
-    // left → -w), prev sits to the left (slide row right → +w).
-    const out = direction === 'next' ? -w : w;
+  // Coalesced detail fetch: stores the result in the shared cache and bumps the
+  // version so every mounted pane (and the toolbar) re-reads it. Concurrent
+  // calls for the same id share a single in-flight request.
+  const inFlight = React.useRef(new Map<string, Promise<Email | null>>()).current;
+  const ensureDetail = React.useCallback((id: string): Promise<Email | null> => {
+    const pending = inFlight.get(id);
+    if (pending) return pending;
+    const p = getEmailDetail(id, jmapAccountId)
+      .then((fetched) => { detailCache.set(id, fetched); bumpCache(); return fetched; })
+      .catch(() => detailCache.get(id) ?? null)
+      .finally(() => { inFlight.delete(id); });
+    inFlight.set(id, p);
+    return p;
+  }, [getEmailDetail, jmapAccountId, detailCache, bumpCache, inFlight]);
 
-    // Best-effort: ensure the target detail is cached so the recentred pane has
-    // content. Neighbours are normally prefetched, so this is usually a no-op.
-    if (!detailCache.has(target.id)) {
-      getEmailDetail(target.id, jmapAccountId)
-        .then((e) => { detailCache.set(target.id, e); bumpCache(); })
-        .catch(() => { /* the load effect will retry once it becomes active */ });
-    }
+  // Slide to a page by index and reflect it in the toolbar immediately; a swipe
+  // that settles on the same page confirms the same id via onMomentumEnd.
+  const goToIndex = React.useCallback((index: number) => {
+    if (index < 0 || index >= emails.length) return;
+    listRef.current?.scrollToOffset({ offset: index * windowWidth, animated: true });
+    const target = emails[index];
+    if (target) setActiveEmailId(target.id);
+  }, [emails, windowWidth]);
 
-    Animated.timing(drag, {
-      toValue: out, duration: 230, easing: Easing.out(Easing.cubic), useNativeDriver: true,
-    }).start(({ finished }) => {
-      if (!finished) { animatingRef.current = false; return; }
-      // Re-point at the neighbour; the drag reset happens in the layout effect
-      // below, in the same commit that re-keys the panes. Resetting here would
-      // recentre the row while the *old* arrangement is still on screen,
-      // flashing the previous email for a frame until React catches up.
-      pendingRecentreRef.current = true;
-      setActiveEmailId(target.id);
-    });
-  }, [drag, detailCache, getEmailDetail, jmapAccountId, bumpCache]);
-  const switchEmailRef = React.useRef(switchEmail);
-  switchEmailRef.current = switchEmail;
+  // Adopt the centred page as the active message once a swipe settles.
+  const onMomentumEnd = React.useCallback((e: NativeSyntheticEvent<NativeScrollEvent>) => {
+    const index = Math.round(e.nativeEvent.contentOffset.x / windowWidth);
+    const target = emails[index];
+    if (target && target.id !== activeEmailId) setActiveEmailId(target.id);
+  }, [emails, windowWidth, activeEmailId]);
 
-  // Recentre the row in the same commit that re-pointed the panes: the pane
-  // that slid to centre is now the middle pane (same key, same mounted
-  // WebView), so snapping the translation back to 0 is invisible.
+  // Page offsets are in window-width units, so a rotation / resize invalidates
+  // the scroll position — re-centre the active page after the width changes.
   React.useLayoutEffect(() => {
-    if (!pendingRecentreRef.current) return;
-    pendingRecentreRef.current = false;
-    drag.setValue(0);
-    animatingRef.current = false;
-  }, [activeEmailId, drag]);
+    const index = emails.findIndex((e) => e.id === activeEmailId);
+    if (index >= 0) listRef.current?.scrollToOffset({ offset: index * windowWidth, animated: false });
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [windowWidth]);
 
-  const panResponder = React.useRef(
-    PanResponder.create({
-      onMoveShouldSetPanResponder: (_, g) => {
-        if (animatingRef.current) return false;
-        if (Math.abs(g.dx) < 10) return false;
-        // Only claim clearly-horizontal drags so the body's vertical scroll
-        // (and link taps) keep working.
-        return Math.abs(g.dx) > Math.abs(g.dy) * 1.5;
-      },
-      onPanResponderMove: (_, g) => {
-        let dx = g.dx;
-        // Rubber-band when there's no neighbour to reach in that direction.
-        if ((dx > 0 && !prevEmailRef.current) || (dx < 0 && !nextEmailRef.current)) {
-          dx *= 0.25;
-        }
-        drag.setValue(dx);
-      },
-      onPanResponderRelease: (_, g) => {
-        const w = windowWidthRef.current;
-        const threshold = Math.min(w * 0.28, 120);
-        const fast = Math.abs(g.vx) > 0.5;
-        if ((g.dx <= -threshold || (fast && g.vx < 0)) && nextEmailRef.current) {
-          switchEmailRef.current('next');
-        } else if ((g.dx >= threshold || (fast && g.vx > 0)) && prevEmailRef.current) {
-          switchEmailRef.current('prev');
-        } else {
-          Animated.spring(drag, { toValue: 0, useNativeDriver: true, speed: 20, bounciness: 6 }).start();
-        }
-      },
-      onPanResponderTerminate: () => {
-        Animated.spring(drag, { toValue: 0, useNativeDriver: true, speed: 20, bounciness: 6 }).start();
-      },
-      onPanResponderTerminationRequest: () => true,
-    }),
-  ).current;
+  // While the body is pinch-zoomed (or a pinch is in flight) horizontal
+  // gestures pan the zoomed content, so the pager must not treat them as page
+  // swipes. Prev/Next stay usable: programmatic scrollToOffset ignores
+  // scrollEnabled. Reset when the active message changes — the zoomed pane's
+  // WebView can unmount without reporting back.
+  const [pagerLocked, setPagerLocked] = React.useState(false);
+  React.useEffect(() => { setPagerLocked(false); }, [activeEmailId]);
 
   const mailAttachmentAction = useSettingsStore((s) => s.mailAttachmentAction);
   const attachmentPosition = useSettingsStore((s) => s.attachmentPosition);
@@ -239,30 +207,26 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
   React.useEffect(() => {
     let cancelled = false;
     let readTimer: ReturnType<typeof setTimeout> | null = null;
-    // If we already have this message cached (e.g. it was prefetched as a
-    // neighbour) it renders immediately; otherwise the pane shows a skeleton
-    // until the fetch below lands. Either way, refresh in the background.
+    // Refresh the active message — a cached copy (the pane may have fetched it,
+    // or it was visited before) renders immediately while this lands. Then mark
+    // it read per the user's delay. The pane itself fetches its own detail, so
+    // ensureDetail here usually rides the same in-flight request.
     setError(null);
     void (async () => {
-      try {
-        const fetched = await getEmailDetail(activeEmailId, jmapAccountId);
-        if (cancelled) return;
-        detailCache.set(activeEmailId, fetched);
-        bumpCache();
-        if (fetched && !fetched.keywords?.$seen) {
-          if (markAsReadDelay > 0) {
-            readTimer = setTimeout(() => {
-              if (!cancelled) void markRead(activeEmailId, jmapAccountId);
-            }, markAsReadDelay);
-          } else {
-            void markRead(activeEmailId, jmapAccountId);
-          }
-        }
-      } catch (e) {
-        // Only surface the error if we have nothing to show; a cached copy is
-        // better than an error screen when the refresh fails.
-        if (!cancelled && !detailCache.has(activeEmailId)) {
-          setError(e instanceof Error ? e.message : 'Failed to load email');
+      const fetched = await ensureDetail(activeEmailId);
+      if (cancelled) return;
+      if (!fetched) {
+        // Only surface an error if there's nothing cached to show.
+        if (!detailCache.has(activeEmailId)) setError('Failed to load email');
+        return;
+      }
+      if (!fetched.keywords?.$seen) {
+        if (markAsReadDelay > 0) {
+          readTimer = setTimeout(() => {
+            if (!cancelled) void markRead(activeEmailId, jmapAccountId);
+          }, markAsReadDelay);
+        } else {
+          void markRead(activeEmailId, jmapAccountId);
         }
       }
     })();
@@ -270,20 +234,7 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
       cancelled = true;
       if (readTimer) clearTimeout(readTimer);
     };
-  }, [activeEmailId, jmapAccountId, getEmailDetail, markRead, markAsReadDelay, detailCache, bumpCache]);
-
-  // Prefetch the adjacent messages so their pane is already populated when the
-  // pager slides it into view. Best-effort and silent; bump the cache version
-  // on arrival so the off-screen neighbour pane renders its content.
-  React.useEffect(() => {
-    for (const neighbour of [prevEmail, nextEmail]) {
-      if (neighbour && !detailCache.has(neighbour.id)) {
-        getEmailDetail(neighbour.id, jmapAccountId)
-          .then((e) => { detailCache.set(neighbour.id, e); bumpCache(); })
-          .catch(() => { /* ignore — prefetch is best-effort */ });
-      }
-    }
-  }, [prevEmail, nextEmail, getEmailDetail, jmapAccountId, detailCache, bumpCache]);
+  }, [activeEmailId, ensureDetail, markRead, markAsReadDelay, jmapAccountId, detailCache]);
 
   const starred = !!email?.keywords?.$flagged;
   const unread = !!email && !email.keywords?.$seen;
@@ -549,43 +500,53 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
         </View>
       ) : (
         <>
-          {/* Three-pane pager: [prev | current | next] live side by side in a
-              row shifted left by one screen, so a horizontal drag slides the
-              neighbour's already-rendered content into view with no gap. */}
-          <View style={styles.pagerViewport}>
-            <Animated.View
-              style={[
-                styles.pagerRow,
-                { width: windowWidth * 3, left: -windowWidth, transform: [{ translateX: drag }] },
-              ]}
-              {...panResponder.panHandlers}
-            >
-              {[prevEmail?.id ?? null, activeEmailId, nextEmail?.id ?? null].map((id, i) => (
-                <View key={id ?? `empty-${i}`} style={{ width: windowWidth }}>
-                  {id ? (
-                    <EmailPane
-                      email={detailCache.get(id) ?? null}
-                      c={c}
-                      styles={styles}
-                      bottomBarHeight={bottomBarHeight}
-                      attachmentPosition={attachmentPosition}
-                      hideInlineImageAttachments={hideInlineImageAttachments}
-                      downloadingBlobId={downloadingBlobId}
-                      onToggleStar={toggleStarFor}
-                      onPressAttachment={onPressAttachment}
-                    />
-                  ) : null}
-                </View>
-              ))}
-            </Animated.View>
-          </View>
+          {/* Pager: a horizontal page-snapping list over the mailbox. Each
+              page is the full-width pane for one message; native scroll slides
+              between them and onMomentumEnd reports the settled page. */}
+          <FlatList
+            ref={listRef}
+            style={styles.pagerViewport}
+            data={emails}
+            extraData={cacheVersion}
+            keyExtractor={(item) => item.id}
+            horizontal
+            pagingEnabled
+            showsHorizontalScrollIndicator={false}
+            initialScrollIndex={initialIndexRef.current}
+            getItemLayout={(_, index) => ({ length: windowWidth, offset: windowWidth * index, index })}
+            windowSize={3}
+            initialNumToRender={1}
+            maxToRenderPerBatch={2}
+            removeClippedSubviews
+            scrollEnabled={!pagerLocked}
+            onMomentumScrollEnd={onMomentumEnd}
+            renderItem={({ item, index }) => (
+              <View style={{ width: windowWidth }}>
+                <EmailPane
+                  id={item.id}
+                  email={detailCache.get(item.id) ?? null}
+                  ensureDetail={ensureDetail}
+                  c={c}
+                  styles={styles}
+                  bottomBarHeight={bottomBarHeight}
+                  attachmentPosition={attachmentPosition}
+                  hideInlineImageAttachments={hideInlineImageAttachments}
+                  downloadingBlobId={downloadingBlobId}
+                  onToggleStar={toggleStarFor}
+                  onPressAttachment={onPressAttachment}
+                  onSwipe={(dir) => goToIndex(dir === 'next' ? index + 1 : index - 1)}
+                  onZoomChange={(z) => setPagerLocked(z.pinching || z.zoomed)}
+                />
+              </View>
+            )}
+          />
 
           {/* Bottom action bar */}
           <View style={[styles.bottomBar, { paddingBottom: Math.max(insets.bottom, 4) }]}>
             <BottomBarButton
               icon={<ChevronLeft size={20} color={c.textMuted} />}
               label="Prev"
-              onPress={prevEmail ? () => switchEmail('prev') : undefined}
+              onPress={prevEmail ? () => goToIndex(currentIndex - 1) : undefined}
               disabled={!prevEmail}
             />
             {bottomActions.map((id) => {
@@ -603,7 +564,7 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
             <BottomBarButton
               icon={<ChevronRight size={20} color={c.textMuted} />}
               label="Next"
-              onPress={nextEmail ? () => switchEmail('next') : undefined}
+              onPress={nextEmail ? () => goToIndex(currentIndex + 1) : undefined}
               disabled={!nextEmail}
             />
           </View>
@@ -668,7 +629,9 @@ export default function EmailThreadScreen({ route, navigation }: Props) {
 }
 
 interface EmailPaneProps {
+  id: string;
   email: Email | null;
+  ensureDetail: (id: string) => Promise<Email | null>;
   c: ThemePalette;
   styles: ReturnType<typeof makeStyles>;
   bottomBarHeight: number;
@@ -677,6 +640,8 @@ interface EmailPaneProps {
   downloadingBlobId: string | null;
   onToggleStar: (email: Email) => void;
   onPressAttachment: (email: Email, blobId: string, name: string | undefined, type: string | undefined) => void;
+  onSwipe: (direction: 'prev' | 'next') => void;
+  onZoomChange: (zoom: { pinching: boolean; zoomed: boolean }) => void;
 }
 
 // One swipeable page: the scrollable subject / sender / attachments / body for a
@@ -685,14 +650,25 @@ interface EmailPaneProps {
 // scroll position and "show all attachments" toggle, and renders directly from
 // the email passed to it — neighbours show real content, not a placeholder.
 function EmailPane({
-  email, c, styles, bottomBarHeight, attachmentPosition,
-  hideInlineImageAttachments, downloadingBlobId, onToggleStar, onPressAttachment,
+  id, email, ensureDetail, c, styles, bottomBarHeight, attachmentPosition,
+  hideInlineImageAttachments, downloadingBlobId, onToggleStar, onPressAttachment, onSwipe,
+  onZoomChange,
 }: EmailPaneProps) {
   const [attachmentsExpanded, setAttachmentsExpanded] = React.useState(false);
+  // Freeze the pane's vertical scroll while a pinch is in flight so a two-
+  // finger zoom can't fling the page; while merely zoomed, vertical scrolling
+  // stays on — it is how the user pans the (taller) zoomed content vertically.
+  const [pinching, setPinching] = React.useState(false);
 
-  // Detail not fetched yet (initial open, or a neighbour the prefetch hasn't
-  // caught up with). Show a skeleton of the pane layout instead of a spinner
-  // so the transition into real content doesn't jump.
+  // Each pane owns loading its own message: when the list mounts this page and
+  // its detail isn't cached yet, fetch it (coalesced upstream). The shared
+  // cache then re-renders the pane with real content.
+  React.useEffect(() => {
+    if (!email) void ensureDetail(id);
+  }, [id, email, ensureDetail]);
+
+  // Detail not fetched yet. Show a skeleton of the pane layout instead of a
+  // spinner so the transition into real content doesn't jump.
   if (!email) {
     return <EmailPaneSkeleton styles={styles} />;
   }
@@ -763,26 +739,19 @@ function EmailPane({
     <ScrollView
       style={styles.scroll}
       contentContainerStyle={{ paddingBottom: bottomBarHeight + spacing.lg }}
+      scrollEnabled={!pinching}
     >
       {/* Subject block */}
       <View style={styles.subjectBlock}>
         <View style={styles.subjectRow}>
-          <View style={styles.subjectMain}>
-            <Pressable onPress={() => onToggleStar(email)} hitSlop={8} style={styles.subjectStar}>
-              <Star
-                size={18}
-                color={starred ? c.starred : c.textMuted}
-                fill={starred ? c.starred : 'transparent'}
-              />
-            </Pressable>
-            <Text style={styles.subjectText}>{subject}</Text>
-          </View>
-          <View style={styles.subjectMeta}>
-            <Text style={styles.subjectDate}>{formatHeaderDate(email.receivedAt)}</Text>
-            {email.size > 0 && (
-              <Text style={styles.subjectSize}>{formatSize(email.size)}</Text>
-            )}
-          </View>
+          <Text style={styles.subjectText}>{subject}</Text>
+          <Pressable onPress={() => onToggleStar(email)} hitSlop={8} style={styles.subjectStar}>
+            <Star
+              size={18}
+              color={starred ? c.starred : c.textMuted}
+              fill={starred ? c.starred : 'transparent'}
+            />
+          </Pressable>
         </View>
       </View>
 
@@ -806,6 +775,13 @@ function EmailPane({
               {email.to?.map((t) => t.name || t.email).join(', ') || '-'}
             </Text>
           </View>
+          <View style={styles.senderMeta}>
+            <Text style={styles.senderDate}>{formatHeaderDate(email.receivedAt)}</Text>
+            <Text style={styles.senderTime}>
+              {formatHeaderTime(email.receivedAt)}
+              {email.size > 0 ? ` · ${formatSize(email.size)}` : ''}
+            </Text>
+          </View>
         </View>
         {attachmentPosition === 'beside-sender' && renderAttachments()}
       </View>
@@ -818,7 +794,12 @@ function EmailPane({
 
       {/* Body */}
       <View style={styles.bodyBlock}>
-        <EmailBodyView email={email} senderEmail={from?.email} />
+        <EmailBodyView
+          email={email}
+          senderEmail={from?.email}
+          onSwipe={onSwipe}
+          onZoomChange={(z) => { setPinching(z.pinching); onZoomChange(z); }}
+        />
       </View>
     </ScrollView>
   );
@@ -845,8 +826,7 @@ function EmailPaneSkeleton({ styles }: { styles: ReturnType<typeof makeStyles> }
   return (
     <Animated.View style={[styles.scroll, { opacity: pulse }]}>
       <View style={styles.subjectBlock}>
-        <View style={[styles.skeletonBone, { height: 20, width: '78%' }]} />
-        <View style={[styles.skeletonBone, { height: 12, width: '36%', marginTop: spacing.sm }]} />
+        <View style={[styles.skeletonBone, { height: 20, width: '88%' }]} />
       </View>
       <View style={styles.senderBlock}>
         <View style={styles.senderRow}>
@@ -856,6 +836,10 @@ function EmailPaneSkeleton({ styles }: { styles: ReturnType<typeof makeStyles> }
             <View style={[styles.skeletonBone, { height: 11, width: '70%', marginTop: 6 }]} />
             <View style={[styles.skeletonBone, { height: 11, width: '45%', marginTop: 6 }]} />
           </View>
+          <View style={styles.senderMeta}>
+            <View style={[styles.skeletonBone, { height: 11, width: 86 }]} />
+            <View style={[styles.skeletonBone, { height: 11, width: 64, marginTop: 6 }]} />
+          </View>
         </View>
       </View>
       <View style={styles.skeletonBody}>
@@ -1188,9 +1172,8 @@ function makeStyles(c: ThemePalette) {
     padding: spacing.lg,
   },
   errorText: { ...typography.body, color: c.error, textAlign: 'center' },
-  // Pager: a clipping viewport with a 3-screen-wide row of panes inside it.
-  pagerViewport: { flex: 1, overflow: 'hidden', backgroundColor: c.background },
-  pagerRow: { position: 'absolute', top: 0, bottom: 0, flexDirection: 'row' },
+  // Pager: the horizontal page-snapping list fills the area between the bars.
+  pagerViewport: { flex: 1, backgroundColor: c.background },
   scroll: { flex: 1, backgroundColor: c.background },
 
   // Subject block
@@ -1206,12 +1189,6 @@ function makeStyles(c: ThemePalette) {
     alignItems: 'flex-start',
     gap: spacing.sm,
   },
-  subjectMain: {
-    flex: 1,
-    flexDirection: 'row',
-    alignItems: 'flex-start',
-    gap: spacing.sm,
-  },
   subjectStar: {
     paddingTop: 4,
   },
@@ -1223,18 +1200,6 @@ function makeStyles(c: ThemePalette) {
     color: c.text,
     letterSpacing: -0.2,
   },
-  subjectMeta: {
-    alignItems: 'flex-end',
-  },
-  subjectDate: {
-    ...typography.caption,
-    color: c.textSecondary,
-  },
-  subjectSize: {
-    ...typography.caption,
-    color: c.textMuted,
-    marginTop: 2,
-  },
 
   // Sender block
   senderBlock: {
@@ -1267,6 +1232,19 @@ function makeStyles(c: ThemePalette) {
   senderRecipientsLabel: {
     color: c.textMuted,
   },
+  senderMeta: {
+    alignItems: 'flex-end',
+    paddingTop: 1,
+  },
+  senderDate: {
+    ...typography.caption,
+    color: c.textSecondary,
+  },
+  senderTime: {
+    ...typography.caption,
+    color: c.textMuted,
+    marginTop: 2,
+  },
 
   // Attachments
   attachmentsBlock: {

src/screens/FilesScreen.tsx

@@ -16,7 +16,7 @@ import {
 import {
   ChevronLeft, FileText, Folder, FolderPlus, HardDrive, FileImage, FileVideo,
   FileAudio, FileArchive, FileSpreadsheet, FileCode2, LayoutGrid, List as ListIcon,
-  MoreVertical, Pencil, Share2, Trash2, Upload, X, Download,
+  MoreVertical, Pencil, Share2, Trash2, Upload, Users, X, Download,
 } from 'lucide-react-native';
 
 // expo-document-picker is loaded lazily on first upload. Its native module
@@ -38,9 +38,8 @@ function loadDocumentPicker(): DocumentPickerModule | null {
 }
 
 import {
-  createFolder, deleteWithDescendants, getAllFileNodes, isDirectChildOfPrefix,
-  isDirectory, nodeDisplayName, pathToPrefix, PATH_SEP, renameFileNode,
-  uploadFileNode,
+  createFolder, deleteFileNodes, getAllFileNodesAcrossAccounts, isCrossAccountId,
+  isFolder, renameFileNode, supportsSharing, uploadFileNode,
 } from '../api/files';
 import { downloadAttachment, shareAttachment } from '../lib/email-export';
 import type { FileNode } from '../api/types';
@@ -48,9 +47,9 @@ import { spacing, radius, typography, type ThemePalette } from '../theme/tokens'
 import { useColors } from '../theme/colors';
 import { useSettingsStore, type FilesViewMode } from '../stores/settings-store';
 import Dialog from '../components/Dialog';
+import ShareSheet from '../components/files/ShareSheet';
 
-// A file row carries the resolved display name alongside the original
-// server-side name (the path-encoded `node.name` field).
+// A file row carries the display name alongside the rest of the node.
 interface FileRow extends FileNode {
   displayName: string;
 }
@@ -108,7 +107,10 @@ export default function FilesScreen() {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
 
-  const [path, setPath] = useState<string[]>([]);
+  // Folder navigation stack. Hierarchy is real parentId nesting (#379) — each
+  // entry is the folder's node id (namespaced "accountId:nodeId" inside a
+  // shared-with-me subtree) plus its name for the breadcrumb.
+  const [path, setPath] = useState<{ id: string; name: string }[]>([]);
   const [allNodes, setAllNodes] = useState<FileNode[]>([]);
   const [loading, setLoading] = useState(true);
   const [refreshing, setRefreshing] = useState(false);
@@ -124,6 +126,7 @@ export default function FilesScreen() {
   const [renameTarget, setRenameTarget] = useState<FileRow | null>(null);
   const [renameValue, setRenameValue] = useState('');
   const [actionsTarget, setActionsTarget] = useState<FileRow | null>(null);
+  const [shareTarget, setShareTarget] = useState<FileRow | null>(null);
 
   const showIcons = useSettingsStore((s) => s.filesShowIcons);
   const coloredIcons = useSettingsStore((s) => s.filesColoredIcons);
@@ -137,8 +140,13 @@ export default function FilesScreen() {
   const viewMode: FilesViewMode = viewOverride ?? defaultViewMode;
 
   const selectionMode = selection.size > 0;
-  const prefix = useMemo(() => pathToPrefix(path), [path]);
-  const headerName = path.length === 0 ? 'Files' : path[path.length - 1];
+  const currentParentId = path.length === 0 ? null : path[path.length - 1].id;
+  // True while browsing inside a folder another principal shared with us.
+  // Creates/uploads would have to route to the owner's account, which this
+  // screen doesn't do (matches the webmail's Files app); writes are hidden.
+  const inSharedSubtree = isCrossAccountId(currentParentId);
+  const headerName = path.length === 0 ? 'Files' : path[path.length - 1].name;
+  const sharingEnabled = supportsSharing();
 
   const loadFiles = useCallback(
     async (mode: 'initial' | 'refresh' = 'initial') => {
@@ -146,7 +154,9 @@ export default function FilesScreen() {
       else setLoading(true);
       setError(null);
       try {
-        const nodes = await getAllFileNodes();
+        // One fetch across all accessible accounts: own files plus nodes other
+        // principals shared with us (tagged isShared, ids namespaced).
+        const nodes = await getAllFileNodesAcrossAccounts();
         setAllNodes(nodes);
       } catch (e) {
         setError(e instanceof Error ? e.message : 'Failed to load files');
@@ -162,33 +172,49 @@ export default function FilesScreen() {
     void loadFiles();
   }, [loadFiles]);
 
-  // If we navigated into a folder that no longer exists (it was deleted, or
-  // we never had it), walk back up until we land on one that does. The check
-  // looks for a directory node whose serverName matches the encoded path.
+  // If we navigated into a folder that no longer exists (deleted, or its
+  // share was revoked), cut the stack back to the deepest ancestor that does.
   useEffect(() => {
     if (allNodes.length === 0) return;
     setPath((prev) => {
-      let next = prev;
-      while (next.length > 0) {
-        const parentPrefix = pathToPrefix(next.slice(0, -1));
-        const expectedName = parentPrefix + next[next.length - 1];
-        const exists = allNodes.some((n) => n.name === expectedName && isDirectory(n));
-        if (exists) break;
-        next = next.slice(0, -1);
+      const byId = new Map(allNodes.map((n) => [n.id, n]));
+      let cut = prev.length;
+      for (let i = 0; i < prev.length; i++) {
+        const node = byId.get(prev[i].id);
+        if (!node || !isFolder(node)) {
+          cut = i;
+          break;
+        }
       }
-      return next.length === prev.length ? prev : next;
+      return cut === prev.length ? prev : prev.slice(0, cut);
     });
   }, [allNodes]);
 
   const visibleFiles = useMemo<FileRow[]>(() => {
-    const rows = allNodes
-      .filter((n) => isDirectChildOfPrefix(n, prefix))
-      .map<FileRow>((n) => ({ ...n, displayName: nodeDisplayName(n, prefix) }))
+    let nodes: FileNode[];
+    if (currentParentId === null) {
+      // Root: our own top-level nodes, plus the roots of every shared-with-me
+      // subtree (a shared node whose parent isn't visible to us).
+      const idSet = new Set(allNodes.map((n) => n.id));
+      nodes = allNodes.filter((n) =>
+        n.isShared
+          ? n.parentId == null || !idSet.has(n.parentId)
+          : (n.parentId ?? null) === null,
+      );
+    } else {
+      nodes = allNodes.filter((n) => (n.parentId ?? null) === currentParentId);
+    }
+    const rows = nodes
+      .map<FileRow>((n) => ({ ...n, displayName: n.name }))
       .filter((r) => showHiddenFiles || !r.displayName.startsWith('.'));
     const dir = sortDir === 'desc' ? -1 : 1;
     return rows.sort((a, b) => {
-      const aDir = isDirectory(a) ? 0 : 1;
-      const bDir = isDirectory(b) ? 0 : 1;
+      // Own content first, shared-with-me entries after (root only).
+      const aShared = a.isShared ? 1 : 0;
+      const bShared = b.isShared ? 1 : 0;
+      if (aShared !== bShared) return aShared - bShared;
+      const aDir = isFolder(a) ? 0 : 1;
+      const bDir = isFolder(b) ? 0 : 1;
       if (aDir !== bDir) return aDir - bDir;
       switch (sortKey) {
         case 'size':
@@ -203,15 +229,18 @@ export default function FilesScreen() {
           return a.displayName.localeCompare(b.displayName) * dir;
       }
     });
-  }, [allNodes, prefix, showHiddenFiles, sortKey, sortDir]);
+  }, [allNodes, currentParentId, showHiddenFiles, sortKey, sortDir]);
 
   const clearSelection = useCallback(() => setSelection(new Set()), []);
 
-  const toggleSelect = useCallback((id: string) => {
+  // Shared-with-me rows stay out of multi-select: batch delete routes to our
+  // own account and would fail (or worse, mismatch) on namespaced ids.
+  const toggleSelect = useCallback((row: FileRow) => {
+    if (row.isShared) return;
     setSelection((prev) => {
       const next = new Set(prev);
-      if (next.has(id)) next.delete(id);
-      else next.add(id);
+      if (next.has(row.id)) next.delete(row.id);
+      else next.add(row.id);
       return next;
     });
   }, []);
@@ -220,7 +249,7 @@ export default function FilesScreen() {
     if (!row.blobId) return;
     setBusyId(row.id);
     try {
-      await shareAttachment(row.blobId, row.displayName, row.type);
+      await shareAttachment(row.blobId, row.displayName, row.type, undefined, row.accountId);
     } catch (e) {
       Alert.alert('Preview failed', e instanceof Error ? e.message : String(e));
     } finally {
@@ -232,7 +261,7 @@ export default function FilesScreen() {
     if (!row.blobId) return;
     setBusyId(row.id);
     try {
-      await downloadAttachment(row.blobId, row.displayName, row.type);
+      await downloadAttachment(row.blobId, row.displayName, row.type, undefined, row.accountId);
     } catch (e) {
       Alert.alert('Download failed', e instanceof Error ? e.message : String(e));
     } finally {
@@ -243,11 +272,11 @@ export default function FilesScreen() {
   const handleRowPress = useCallback(
     (row: FileRow) => {
       if (selectionMode) {
-        toggleSelect(row.id);
+        toggleSelect(row);
         return;
       }
-      if (isDirectory(row)) {
-        setPath((p) => [...p, row.displayName]);
+      if (isFolder(row)) {
+        setPath((p) => [...p, { id: row.id, name: row.displayName }]);
         return;
       }
       void previewFile(row);
@@ -256,7 +285,7 @@ export default function FilesScreen() {
   );
 
   const handleRowLongPress = useCallback((row: FileRow) => {
-    toggleSelect(row.id);
+    toggleSelect(row);
   }, [toggleSelect]);
 
   const goBack = useCallback(() => {
@@ -277,19 +306,19 @@ export default function FilesScreen() {
   const submitNewFolder = useCallback(async () => {
     const name = newFolderName.trim();
     if (!name) return;
-    if (name.includes(PATH_SEP) || name.includes('/')) {
+    if (name.includes('/')) {
       Alert.alert('Invalid name', 'Folder names cannot contain "/".');
       return;
     }
     setNewFolderOpen(false);
     setNewFolderName('');
     try {
-      await createFolder(name, path);
+      await createFolder(name, currentParentId);
       await loadFiles('refresh');
     } catch (e) {
       Alert.alert('Create folder failed', e instanceof Error ? e.message : String(e));
     }
-  }, [newFolderName, path, loadFiles]);
+  }, [newFolderName, currentParentId, loadFiles]);
 
   const submitRename = useCallback(async () => {
     if (!renameTarget) return;
@@ -298,7 +327,7 @@ export default function FilesScreen() {
       setRenameTarget(null);
       return;
     }
-    if (name.includes(PATH_SEP) || name.includes('/')) {
+    if (name.includes('/')) {
       Alert.alert('Invalid name', 'Names cannot contain "/".');
       return;
     }
@@ -306,12 +335,12 @@ export default function FilesScreen() {
     setRenameTarget(null);
     setRenameValue('');
     try {
-      await renameFileNode(target, name, path, allNodes);
+      await renameFileNode(target.id, name);
       await loadFiles('refresh');
     } catch (e) {
       Alert.alert('Rename failed', e instanceof Error ? e.message : String(e));
     }
-  }, [renameTarget, renameValue, path, allNodes, loadFiles]);
+  }, [renameTarget, renameValue, loadFiles]);
 
   const startUpload = useCallback(async () => {
     if (uploading) return;
@@ -341,7 +370,7 @@ export default function FilesScreen() {
         asset.uri,
         asset.name,
         asset.mimeType || 'application/octet-stream',
-        path,
+        currentParentId,
       );
       await loadFiles('refresh');
     } catch (e) {
@@ -349,7 +378,7 @@ export default function FilesScreen() {
     } finally {
       setUploading(false);
     }
-  }, [uploading, path, loadFiles]);
+  }, [uploading, currentParentId, loadFiles]);
 
   const requestDelete = useCallback((rows: FileRow[]) => {
     if (rows.length === 0) return;
@@ -362,12 +391,13 @@ export default function FilesScreen() {
     setConfirmDelete(null);
     clearSelection();
     try {
-      await deleteWithDescendants(targets, allNodes);
+      // The server removes folder descendants (onDestroyRemoveChildren).
+      await deleteFileNodes(targets.map((t) => t.id));
       await loadFiles('refresh');
     } catch (e) {
       Alert.alert('Delete failed', e instanceof Error ? e.message : String(e));
     }
-  }, [confirmDelete, allNodes, clearSelection, loadFiles]);
+  }, [confirmDelete, clearSelection, loadFiles]);
 
   const renderHeader = () => {
     const canBack = path.length > 0;
@@ -409,27 +439,31 @@ export default function FilesScreen() {
             </Text>
           </View>
           <View style={styles.headerActions}>
-            <Pressable
-              onPress={() => setNewFolderOpen(true)}
-              hitSlop={8}
-              style={styles.headerBtn}
-              accessibilityLabel="New folder"
-            >
-              <FolderPlus size={20} color={c.text} />
-            </Pressable>
-            <Pressable
-              onPress={() => void startUpload()}
-              hitSlop={8}
-              style={styles.headerBtn}
-              accessibilityLabel="Upload file"
-              disabled={uploading}
-            >
-              {uploading ? (
-                <ActivityIndicator size="small" color={c.text} />
-              ) : (
-                <Upload size={20} color={c.text} />
-              )}
-            </Pressable>
+            {!inSharedSubtree ? (
+              <Pressable
+                onPress={() => setNewFolderOpen(true)}
+                hitSlop={8}
+                style={styles.headerBtn}
+                accessibilityLabel="New folder"
+              >
+                <FolderPlus size={20} color={c.text} />
+              </Pressable>
+            ) : null}
+            {!inSharedSubtree ? (
+              <Pressable
+                onPress={() => void startUpload()}
+                hitSlop={8}
+                style={styles.headerBtn}
+                accessibilityLabel="Upload file"
+                disabled={uploading}
+              >
+                {uploading ? (
+                  <ActivityIndicator size="small" color={c.text} />
+                ) : (
+                  <Upload size={20} color={c.text} />
+                )}
+              </Pressable>
+            ) : null}
             <Pressable
               onPress={toggleView}
               hitSlop={8}
@@ -442,7 +476,7 @@ export default function FilesScreen() {
         </View>
         {canBack ? (
           <Text style={styles.breadcrumb} numberOfLines={1}>
-            {['Files', ...path].join(' / ')}
+            {['Files', ...path.map((p) => p.name)].join(' / ')}
           </Text>
         ) : null}
       </View>
@@ -450,13 +484,14 @@ export default function FilesScreen() {
   };
 
   const renderRow = (item: FileRow) => {
-    const isDir = isDirectory(item);
+    const isDir = isFolder(item);
     const Icon = isDir ? Folder : pickFileIcon(item.displayName);
     const tint = isDir
       ? (coloredIcons ? c.calendar.blue : c.textMuted)
       : (coloredIcons ? fileIconColor(item.displayName, c) : c.textMuted);
     const selected = selection.has(item.id);
     const busy = busyId === item.id;
+    const sharedOut = !!item.shareWith && Object.keys(item.shareWith).length > 0;
     return (
       <Pressable
         onPress={() => handleRowPress(item)}
@@ -470,10 +505,22 @@ export default function FilesScreen() {
       >
         {showIcons && <Icon size={20} color={tint} />}
         <View style={styles.fileInfo}>
-          <Text style={styles.fileName} numberOfLines={1}>
-            {item.displayName}
-          </Text>
+          <View style={styles.fileNameRow}>
+            <Text style={styles.fileName} numberOfLines={1}>
+              {item.displayName}
+            </Text>
+            {item.isShared ? (
+              <Share2 size={13} color={c.primary} />
+            ) : sharedOut ? (
+              <Users size={13} color={c.primary} />
+            ) : null}
+          </View>
           <View style={styles.fileMetaRow}>
+            {item.isShared && item.accountName ? (
+              <Text style={styles.fileMeta} numberOfLines={1}>
+                Shared by {item.accountName}
+              </Text>
+            ) : null}
             {item.size != null && !isDir ? (
               <Text style={styles.fileMeta}>{formatFileSize(item.size)}</Text>
             ) : null}
@@ -501,12 +548,13 @@ export default function FilesScreen() {
   };
 
   const renderGridCell = (item: FileRow) => {
-    const isDir = isDirectory(item);
+    const isDir = isFolder(item);
     const Icon = isDir ? Folder : pickFileIcon(item.displayName);
     const tint = isDir
       ? (coloredIcons ? c.calendar.blue : c.textMuted)
       : (coloredIcons ? fileIconColor(item.displayName, c) : c.textMuted);
     const selected = selection.has(item.id);
+    const sharedOut = !!item.shareWith && Object.keys(item.shareWith).length > 0;
     return (
       <Pressable
         onPress={() => handleRowPress(item)}
@@ -523,10 +571,21 @@ export default function FilesScreen() {
         ) : (
           <View style={{ width: 36, height: 36 }} />
         )}
-        <Text style={styles.gridName} numberOfLines={2}>
-          {item.displayName}
-        </Text>
-        {item.size != null && !isDir ? (
+        <View style={styles.gridNameRow}>
+          <Text style={styles.gridName} numberOfLines={2}>
+            {item.displayName}
+          </Text>
+          {item.isShared ? (
+            <Share2 size={12} color={c.primary} />
+          ) : sharedOut ? (
+            <Users size={12} color={c.primary} />
+          ) : null}
+        </View>
+        {item.isShared && item.accountName ? (
+          <Text style={styles.gridMeta} numberOfLines={1}>
+            Shared by {item.accountName}
+          </Text>
+        ) : item.size != null && !isDir ? (
           <Text style={styles.gridMeta} numberOfLines={1}>
             {formatFileSize(item.size)}
           </Text>
@@ -627,6 +686,7 @@ export default function FilesScreen() {
 
       <ActionsSheet
         target={actionsTarget}
+        sharingEnabled={sharingEnabled}
         onClose={() => setActionsTarget(null)}
         onPreview={(r) => {
           setActionsTarget(null);
@@ -636,6 +696,10 @@ export default function FilesScreen() {
           setActionsTarget(null);
           void downloadFile(r);
         }}
+        onShare={(r) => {
+          setActionsTarget(null);
+          setShareTarget(r);
+        }}
         onRename={(r) => {
           setActionsTarget(null);
           setRenameTarget(r);
@@ -647,6 +711,12 @@ export default function FilesScreen() {
         }}
       />
 
+      <ShareSheet
+        node={shareTarget}
+        onClose={() => setShareTarget(null)}
+        onChanged={() => void loadFiles('refresh')}
+      />
+
       <Dialog
         visible={confirmDelete != null}
         title={
@@ -722,18 +792,24 @@ function PromptModal(props: PromptModalProps) {
 
 interface ActionsSheetProps {
   target: FileRow | null;
+  sharingEnabled: boolean;
   onClose: () => void;
   onPreview: (r: FileRow) => void;
   onDownload: (r: FileRow) => void;
+  onShare: (r: FileRow) => void;
   onRename: (r: FileRow) => void;
   onDelete: (r: FileRow) => void;
 }
 
-function ActionsSheet({ target, onClose, onPreview, onDownload, onRename, onDelete }: ActionsSheetProps) {
+function ActionsSheet({ target, sharingEnabled, onClose, onPreview, onDownload, onShare, onRename, onDelete }: ActionsSheetProps) {
   const c = useColors();
   const styles = React.useMemo(() => makeSheetStyles(c), [c]);
   if (!target) return null;
-  const isDir = isDirectory(target);
+  const isDir = isFolder(target);
+  // Owned nodes report full rights (or no myRights at all); shared-with-me
+  // nodes are managed by their owner, and write ops would have to route to
+  // the owner's account — so they only get preview/download here.
+  const canShare = sharingEnabled && !target.isShared && (target.myRights?.mayShare ?? true);
   return (
     <Modal visible transparent animationType="slide" onRequestClose={onClose}>
       <TouchableWithoutFeedback onPress={onClose}>
@@ -755,14 +831,24 @@ function ActionsSheet({ target, onClose, onPreview, onDownload, onRename, onDele
                   <Text style={styles.actionLabel}>Save to device</Text>
                 </Pressable>
               ) : null}
-              <Pressable style={styles.action} onPress={() => onRename(target)}>
-                <Pencil size={18} color={c.text} />
-                <Text style={styles.actionLabel}>Rename</Text>
-              </Pressable>
-              <Pressable style={styles.action} onPress={() => onDelete(target)}>
-                <Trash2 size={18} color={c.error} />
-                <Text style={[styles.actionLabel, { color: c.error }]}>Delete</Text>
-              </Pressable>
+              {canShare ? (
+                <Pressable style={styles.action} onPress={() => onShare(target)}>
+                  <Users size={18} color={c.text} />
+                  <Text style={styles.actionLabel}>Sharing & access</Text>
+                </Pressable>
+              ) : null}
+              {!target.isShared ? (
+                <Pressable style={styles.action} onPress={() => onRename(target)}>
+                  <Pencil size={18} color={c.text} />
+                  <Text style={styles.actionLabel}>Rename</Text>
+                </Pressable>
+              ) : null}
+              {!target.isShared ? (
+                <Pressable style={styles.action} onPress={() => onDelete(target)}>
+                  <Trash2 size={18} color={c.error} />
+                  <Text style={[styles.actionLabel, { color: c.error }]}>Delete</Text>
+                </Pressable>
+              ) : null}
             </View>
           </TouchableWithoutFeedback>
         </View>
@@ -856,9 +942,15 @@ function makeStyles(c: ThemePalette) {
     fileInfo: {
       flex: 1,
     },
+    fileNameRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      gap: spacing.xs,
+    },
     fileName: {
       fontSize: typography.body.fontSize,
       color: c.text,
+      flexShrink: 1,
     },
     fileMetaRow: {
       flexDirection: 'row',
@@ -886,10 +978,18 @@ function makeStyles(c: ThemePalette) {
       paddingHorizontal: spacing.xs,
       borderRadius: radius.md,
     },
+    gridNameRow: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      justifyContent: 'center',
+      gap: 4,
+      maxWidth: '100%',
+    },
     gridName: {
       fontSize: typography.caption.fontSize,
       color: c.text,
       textAlign: 'center',
+      flexShrink: 1,
     },
     gridMeta: {
       fontSize: typography.small.fontSize,

src/stores/__tests__/calendar-store.test.ts

@@ -7,6 +7,7 @@ vi.mock('../../api/calendar', () => ({
   createEvent: vi.fn(),
   updateEvent: vi.fn(),
   deleteEvents: vi.fn(),
+  setDefaultCalendar: vi.fn(),
 }));
 
 vi.mock('@react-native-async-storage/async-storage', () => ({
@@ -37,6 +38,7 @@ const mockGetEvents = calendarApi.getEvents as ReturnType<typeof vi.fn>;
 const mockCreateEvent = calendarApi.createEvent as ReturnType<typeof vi.fn>;
 const mockUpdateEvent = calendarApi.updateEvent as ReturnType<typeof vi.fn>;
 const mockDeleteEvents = calendarApi.deleteEvents as ReturnType<typeof vi.fn>;
+const mockSetDefaultCalendar = calendarApi.setDefaultCalendar as ReturnType<typeof vi.fn>;
 
 beforeEach(() => {
   vi.clearAllMocks();
@@ -99,6 +101,70 @@ describe('calendar-store', () => {
       expect(useCalendarStore.getState().events).toEqual([]);
       expect(mockGetEvents).not.toHaveBeenCalled();
     });
+
+    it('namespaces shared/group event ids by owning account and keeps the real id in originalId', async () => {
+      // A shared calendar lives in another account; its event id ("ev1") can
+      // collide with one of the user's own events, so the store must namespace
+      // it. Mirrors webmail's mapServerEventToStoreEvent.
+      useCalendarStore.setState({
+        calendars: [
+          { id: 'cal-1', name: 'Personal' } as any,
+          { id: 'shared-cal', name: 'Team', accountId: 'acc-2', isShared: true } as any,
+        ],
+      });
+      mockQueryEvents.mockImplementation(async (_ids: string[], _a: string, _b: string, accountId?: string) =>
+        accountId === 'acc-2' ? ['ev1'] : [],
+      );
+      mockGetEvents.mockImplementation(async (_ids: string[], accountId?: string) =>
+        accountId === 'acc-2'
+          ? [{ id: 'ev1', title: 'Standup', start: '2026-03-15T10:00:00', calendarIds: { 'shared-cal': true } }]
+          : [],
+      );
+
+      await useCalendarStore.getState().fetchEvents(['cal-1', 'shared-cal'], '2026-03-01', '2026-03-31');
+
+      const stored = useCalendarStore.getState().events;
+      expect(stored).toHaveLength(1);
+      expect(stored[0].id).toBe('acc-2:ev1');
+      expect(stored[0].originalId).toBe('ev1');
+      expect(stored[0].accountId).toBe('acc-2');
+    });
+
+    it('routes queries by account when own and shared calendars share a raw id', async () => {
+      // The user's own "default" calendar and a family group's "default"
+      // calendar collide on the raw JMAP id. The shared one is namespaced
+      // (`acc-2:default`, originalId "default"); the query must use the raw id
+      // against acc-2, and the returned event's calendarIds must be remapped to
+      // the namespaced store id so it isn't hidden with the personal calendar.
+      useCalendarStore.setState({
+        calendars: [
+          { id: 'default', name: 'Personal' } as any,
+          { id: 'acc-2:default', originalId: 'default', name: 'Family', accountId: 'acc-2', isShared: true } as any,
+        ],
+      });
+      const queried: Record<string, string[]> = {};
+      mockQueryEvents.mockImplementation(async (ids: string[], _a: string, _b: string, accountId?: string) => {
+        queried[accountId ?? 'primary'] = ids;
+        return accountId === 'acc-2' ? ['fam1'] : [];
+      });
+      mockGetEvents.mockImplementation(async (_ids: string[], accountId?: string) =>
+        accountId === 'acc-2'
+          ? [{ id: 'fam1', title: 'Soccer', start: '2026-03-20T15:00:00', calendarIds: { default: true } }]
+          : [],
+      );
+
+      await useCalendarStore.getState().fetchEvents(['default', 'acc-2:default'], '2026-03-01', '2026-03-31');
+
+      // The shared account is queried with the raw calendar id, not the prefix.
+      expect(queried['acc-2']).toEqual(['default']);
+      const ev = useCalendarStore.getState().events[0];
+      expect(ev.calendarIds).toEqual({ 'acc-2:default': true });
+
+      // Hiding the personal "default" must not hide the family event.
+      useCalendarStore.setState({ hiddenCalendarIds: ['default'] });
+      const visible = selectVisibleEvents(useCalendarStore.getState());
+      expect(visible.map((e) => e.id)).toContain('acc-2:fam1');
+    });
   });
 
   describe('ensureRange', () => {
@@ -110,7 +176,8 @@ describe('calendar-store', () => {
 
       await useCalendarStore.getState().ensureRange('2026-03-01', '2026-03-31');
 
-      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-03-31');
+      // 4th arg is the owning account — undefined for primary-account calendars.
+      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-03-31', undefined);
     });
 
     it('should skip refetch when loaded range covers requested', async () => {
@@ -134,7 +201,7 @@ describe('calendar-store', () => {
 
       await useCalendarStore.getState().ensureRange('2026-04-01', '2026-04-30');
 
-      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-04-30');
+      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-04-30', undefined);
     });
 
     it('should fetch calendars first when none are loaded', async () => {
@@ -144,7 +211,7 @@ describe('calendar-store', () => {
       await useCalendarStore.getState().ensureRange('2026-03-01', '2026-03-31');
 
       expect(mockGetCalendars).toHaveBeenCalled();
-      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-03-31');
+      expect(mockQueryEvents).toHaveBeenCalledWith(['cal-1'], '2026-03-01', '2026-03-31', undefined);
     });
   });
 
@@ -273,8 +340,31 @@ describe('calendar-store', () => {
       );
 
       // The third arg is the iMIP scheduling flag — undefined here since the
-      // event has no participants to notify.
-      expect(mockUpdateEvent).toHaveBeenCalledWith('master', { title: 'New' }, undefined);
+      // event has no participants to notify. The fourth is the owning
+      // account — undefined for primary-account events.
+      expect(mockUpdateEvent).toHaveBeenCalledWith('master', { title: 'New' }, undefined, undefined);
+    });
+  });
+
+  describe('setDefaultCalendar', () => {
+    it('flips isDefault to the chosen calendar within the same account', async () => {
+      useCalendarStore.setState({
+        calendars: [
+          { id: 'cal-1', name: 'A', isDefault: true } as any,
+          { id: 'cal-2', name: 'B' } as any,
+          { id: 'cal-3', name: 'Shared', isShared: true, accountId: 'acc-2', isDefault: true } as any,
+        ],
+      });
+      mockSetDefaultCalendar.mockResolvedValue(undefined);
+
+      await useCalendarStore.getState().setDefaultCalendar('cal-2');
+
+      expect(mockSetDefaultCalendar).toHaveBeenCalledWith('cal-2', undefined);
+      const calendars = useCalendarStore.getState().calendars;
+      expect(calendars.find((c) => c.id === 'cal-1')?.isDefault).toBe(false);
+      expect(calendars.find((c) => c.id === 'cal-2')?.isDefault).toBe(true);
+      // Defaults in other accounts are untouched.
+      expect(calendars.find((c) => c.id === 'cal-3')?.isDefault).toBe(true);
     });
   });
 

src/stores/calendar-store.ts

@@ -12,6 +12,7 @@ import {
   batchCreateEvents as apiBatchCreateEvents,
   rsvpEvent as apiRsvpEvent,
   createCalendar as apiCreateCalendar,
+  setDefaultCalendar as apiSetDefaultCalendar,
 } from '../api/calendar';
 import { jmapClient } from '../api/jmap-client';
 import { expandRecurringEvents } from '../lib/recurrence-expansion';
@@ -24,6 +25,37 @@ function hasSchedulingParticipants(event?: Partial<CalendarEvent> | null): boole
 
 const HIDDEN_CALENDARS_STORAGE_KEY = 'webmail:calendar:hidden:v1';
 
+// Map a server CalendarEvent onto its store representation. For events from a
+// shared/group account the JMAP id is only unique within that account, so we
+// namespace `id` (stashing the real id in originalId) and remap the event's
+// `calendarIds` from raw server ids onto the namespaced store calendar ids so
+// visibility filtering and per-calendar colour lookup line up. Events from the
+// primary account are returned unchanged. Mirrors webmail's
+// mapServerEventToStoreEvent.
+function mapServerEventToStoreEvent(
+  event: CalendarEvent,
+  calendars: Calendar[],
+  accountId?: string,
+): CalendarEvent {
+  if (!accountId) return event;
+  const mapped: Record<string, boolean> = {};
+  for (const [calId, included] of Object.entries(event.calendarIds || {})) {
+    const cal = calendars.find(
+      (c) => (c.originalId || c.id) === calId && c.accountId === accountId,
+    );
+    mapped[cal?.id || calId] = included;
+  }
+  return {
+    ...event,
+    id: `${accountId}:${event.id}`,
+    originalId: event.id,
+    originalCalendarIds: event.calendarIds,
+    calendarIds: Object.keys(mapped).length > 0 ? mapped : event.calendarIds,
+    accountId,
+    isShared: true,
+  };
+}
+
 export interface LoadedRange {
   after: string;
   before: string;
@@ -57,6 +89,7 @@ export interface CalendarState {
   ) => Promise<void>;
   importEvents: (events: Partial<CalendarEvent>[], calendarId: string) => Promise<number>;
   createCalendar: (name: string, color?: string) => Promise<Calendar>;
+  setDefaultCalendar: (id: string) => Promise<void>;
   // Tasks
   createTask: (task: Partial<CalendarEvent>, calendarId: string) => Promise<void>;
   updateTask: (id: string, changes: Partial<CalendarEvent>) => Promise<void>;
@@ -131,8 +164,37 @@ export const useCalendarStore = create<CalendarState>()(
     if (!jmapClient.isConnected) return;
     set({ loading: true, error: null });
     try {
-      const ids = (await queryEvents(calendarIds, after, before)) ?? [];
-      const raw = ids.length > 0 ? ((await fetchEvents(ids)) ?? []) : [];
+      // Group the requested calendars by owning account: the primary account
+      // (calendars without an accountId tag) plus one group per shared
+      // account, since CalendarEvent/query is scoped to a single account. The
+      // incoming ids are store ids (shared calendars are namespaced
+      // `${accountId}:${id}`); map them back to the raw server ids the query
+      // filter expects.
+      const calendars = get().calendars;
+      const byId = new Map(calendars.map((c) => [c.id, c]));
+      const groups = new Map<string | undefined, string[]>();
+      for (const id of calendarIds) {
+        const cal = byId.get(id);
+        const accountId = cal?.accountId;
+        const serverId = cal?.originalId || id;
+        const group = groups.get(accountId);
+        if (group) group.push(serverId);
+        else groups.set(accountId, [serverId]);
+      }
+      if (groups.size === 0) groups.set(undefined, []);
+
+      const raw: CalendarEvent[] = [];
+      for (const [accountId, ids] of groups) {
+        try {
+          const eventIds = (await queryEvents(ids, after, before, accountId)) ?? [];
+          if (eventIds.length === 0) continue;
+          const fetched = (await fetchEvents(eventIds, accountId)) ?? [];
+          raw.push(...fetched.map((e) => mapServerEventToStoreEvent(e, calendars, accountId)));
+        } catch (err) {
+          // A failing shared account must not hide the user's own events.
+          if (!accountId) throw err;
+        }
+      }
       // Stalwart returns both Events and Tasks from CalendarEvent/query. Events
       // have a `start`; tasks are surfaced separately so they don't pollute the
       // grid (they're shown in the task list with their due date instead).
@@ -176,12 +238,19 @@ export const useCalendarStore = create<CalendarState>()(
 
   handleStateChange: async (change) => {
     if (!jmapClient.isConnected) return;
-    const accountId = jmapClient.accountId;
-    const accountChanges = change.changed?.[accountId];
-    if (!accountChanges) return;
-
-    const calendarChanged = 'Calendar' in accountChanges;
-    const eventChanged = 'CalendarEvent' in accountChanges;
+    // Watch the primary account plus every shared account we show calendars
+    // from, so edits the owner makes to a shared calendar refresh the view.
+    const known = new Set<string>([jmapClient.accountId]);
+    for (const cal of get().calendars) {
+      if (cal.accountId) known.add(cal.accountId);
+    }
+    let calendarChanged = false;
+    let eventChanged = false;
+    for (const [accountId, types] of Object.entries(change.changed ?? {})) {
+      if (!known.has(accountId)) continue;
+      if ('Calendar' in types) calendarChanged = true;
+      if ('CalendarEvent' in types) eventChanged = true;
+    }
     if (!calendarChanged && !eventChanged) return;
 
     if (calendarChanged) {
@@ -193,12 +262,22 @@ export const useCalendarStore = create<CalendarState>()(
   },
 
   createEvent: async (event, calendarId) => {
+    // Shared calendars live in the owner's account — route the create there,
+    // and against the calendar's raw server id (calendarId is the namespaced
+    // store id for shared calendars).
+    const calendars = get().calendars;
+    const cal = calendars.find((c) => c.id === calendarId);
+    const accountId = cal?.accountId;
     const created = await apiCreateEvent(
       event,
-      calendarId,
+      cal?.originalId || calendarId,
       hasSchedulingParticipants(event) ? true : undefined,
+      accountId,
     );
-    set({ events: [...get().events, created] });
+    // Map the same way fetchEvents does so the optimistic insert doesn't
+    // collide with the user's own events and stays visible under the right
+    // calendar filter.
+    set({ events: [...get().events, mapServerEventToStoreEvent(created, calendars, accountId)] });
     return created;
   },
 
@@ -210,7 +289,7 @@ export const useCalendarStore = create<CalendarState>()(
     // carry participants.
     const schedule =
       hasSchedulingParticipants(changes) || hasSchedulingParticipants(storeEvent);
-    await apiUpdateEvent(realId, changes, schedule ? true : undefined);
+    await apiUpdateEvent(realId, changes, schedule ? true : undefined, storeEvent?.accountId);
     set({
       events: get().events.map((e) => (e.id === id ? { ...e, ...changes } : e)),
     });
@@ -222,6 +301,7 @@ export const useCalendarStore = create<CalendarState>()(
     await apiDeleteEvents(
       [realId],
       hasSchedulingParticipants(storeEvent) ? true : undefined,
+      storeEvent?.accountId,
     );
     set({ events: get().events.filter((e) => e.id !== id) });
   },
@@ -232,7 +312,7 @@ export const useCalendarStore = create<CalendarState>()(
     }
     const storeEvent = get().events.find((e) => e.id === eventId);
     const realId = storeEvent?.originalId || eventId;
-    await apiRsvpEvent(realId, participantId, status, replyTo);
+    await apiRsvpEvent(realId, participantId, status, replyTo, storeEvent?.accountId);
     set({
       events: get().events.map((e) => {
         if (e.id !== eventId || !e.participants?.[participantId]) return e;
@@ -249,20 +329,26 @@ export const useCalendarStore = create<CalendarState>()(
 
   importEvents: async (events, calendarId) => {
     if (events.length === 0) return 0;
+    // Shared calendars live in the owner's account and carry a namespaced
+    // store id — resolve the raw server id + owning account so dedup and
+    // create target the right place.
+    const cal = get().calendars.find((c) => c.id === calendarId);
+    const accountId = cal?.accountId;
+    const serverCalendarId = cal?.originalId || calendarId;
     // Stalwart enforces UID uniqueness across calendars. Skip events whose UID
     // already exists; create the rest. (We don't attempt cross-calendar linking
     // on mobile — a duplicate is simply skipped.)
     let toCreate = events;
     try {
-      const existingIds = await queryEvents([], '', '');
-      const existing = existingIds.length > 0 ? await fetchEvents(existingIds) : [];
+      const existingIds = await queryEvents([], '', '', accountId);
+      const existing = existingIds.length > 0 ? await fetchEvents(existingIds, accountId) : [];
       const seenUids = new Set(existing.map((e) => e.uid).filter(Boolean) as string[]);
       toCreate = events.filter((e) => !e.uid || !seenUids.has(e.uid));
     } catch {
       // Couldn't dedupe — proceed and let the server reject genuine dupes.
     }
     if (toCreate.length === 0) return 0;
-    const count = await apiBatchCreateEvents(toCreate, calendarId);
+    const count = await apiBatchCreateEvents(toCreate, serverCalendarId, accountId);
     await get().refresh();
     return count;
   },
@@ -273,15 +359,37 @@ export const useCalendarStore = create<CalendarState>()(
     return created;
   },
 
+  setDefaultCalendar: async (id) => {
+    const cal = get().calendars.find((c) => c.id === id);
+    await apiSetDefaultCalendar(cal?.originalId || id, cal?.accountId);
+    set({
+      calendars: get().calendars.map((c) => {
+        if (c.id === id) return { ...c, isDefault: true };
+        // Only one default per account — clear the flag on siblings within
+        // the same account scope.
+        if (c.isDefault && (c.accountId ?? null) === (cal?.accountId ?? null)) {
+          return { ...c, isDefault: false };
+        }
+        return c;
+      }),
+    });
+  },
+
   createTask: async (task, calendarId) => {
-    await apiCreateEvent({ ...task, '@type': 'Task' }, calendarId);
+    const cal = get().calendars.find((c) => c.id === calendarId);
+    await apiCreateEvent(
+      { ...task, '@type': 'Task' },
+      cal?.originalId || calendarId,
+      undefined,
+      cal?.accountId,
+    );
     await get().refresh();
   },
 
   updateTask: async (id, changes) => {
     const task = get().tasks.find((t) => t.id === id);
     const realId = task?.originalId || id;
-    await apiUpdateEvent(realId, changes);
+    await apiUpdateEvent(realId, changes, undefined, task?.accountId);
     set({ tasks: get().tasks.map((t) => (t.id === id ? { ...t, ...changes } : t)) });
   },
 
@@ -298,7 +406,7 @@ export const useCalendarStore = create<CalendarState>()(
   deleteTask: async (id) => {
     const task = get().tasks.find((t) => t.id === id);
     const realId = task?.originalId || id;
-    await apiDeleteEvents([realId]);
+    await apiDeleteEvents([realId], undefined, task?.accountId);
     set({ tasks: get().tasks.filter((t) => t.id !== id) });
   },
 

src/stores/settings-store.ts

@@ -169,6 +169,10 @@ interface PersistedSettings {
   showBirthdayCalendar: boolean;
   enableCalendarTasks: boolean;
   showTasksOnCalendar: boolean;
+  // Per-viewer color overrides for shared calendars, keyed by
+  // sharedCalendarColorKey(). Lets the user recolor calendars shared with
+  // them without changing the owner's color (parity with webmail #345).
+  sharedCalendarColors: Record<string, string>;
 
   // Files
   filesFolderLayout: FilesFolderLayout;
@@ -276,6 +280,7 @@ const DEFAULT_PERSISTED: PersistedSettings = {
   showBirthdayCalendar: true,
   enableCalendarTasks: false,
   showTasksOnCalendar: true,
+  sharedCalendarColors: {},
 
   filesFolderLayout: 'inline',
   filesDefaultViewMode: 'list',
@@ -353,6 +358,10 @@ export interface SettingsState extends PersistedSettings {
   removeTrustedSender: (email: string) => void;
   isSenderTrusted: (email: string) => boolean;
 
+  // Shared-calendar color overrides
+  setSharedCalendarColor: (key: string, color: string) => void;
+  removeSharedCalendarColor: (key: string) => void;
+
   // Sidebar apps
   addSidebarApp: (app: Omit<SidebarApp, 'id'>) => void;
   updateSidebarApp: (id: string, updates: Partial<Omit<SidebarApp, 'id'>>) => void;
@@ -475,6 +484,17 @@ export const useSettingsStore = create<SettingsState>((set, get) => ({
     return get().trustedSenders.includes(normalized);
   },
 
+  setSharedCalendarColor: (key, color) => {
+    set({ sharedCalendarColors: { ...get().sharedCalendarColors, [key]: color } });
+    persist(snapshot(get()));
+  },
+
+  removeSharedCalendarColor: (key) => {
+    const { [key]: _removed, ...rest } = get().sharedCalendarColors;
+    set({ sharedCalendarColors: rest });
+    persist(snapshot(get()));
+  },
+
   addSidebarApp: (app) => {
     const id = `app-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 7)}`;
     set({ sidebarApps: [...get().sidebarApps, { ...app, id }] });