feat: open a calendar link on the view and day it names

src/navigation/__tests__/calendar-date-link.test.ts

@@ -0,0 +1,56 @@
+import { describe, it, expect, vi } from 'vitest';
+import fs from 'node:fs';
+import path from 'node:path';
+import { handleDeepLink, parseDeepLink } from '../linking';
+import { parseCalendarLinkDate, usePendingCalendarDate } from '../pending-calendar-date';
+import { usePendingCalendarOpen } from '../pending-calendar-open';
+
+// A `/calendar/<view>/<yyyy-mm-dd>` link opened only the Calendar tab, on
+// whatever day it showed (file 10 "date deep links", 05 "Deep links to
+// calendar/event"). Webmail lib/deep-links.ts parseCalendarPath.
+
+const nav = () => ({ isReady: () => true, navigate: vi.fn() });
+
+describe('calendar date deep links', () => {
+  it('parses the view and the day, and only real days', () => {
+    expect(parseDeepLink('bulwarkmobile://calendar/week/2026-08-29'))
+      .toEqual({ kind: 'calendar', view: 'week', date: '2026-08-29' });
+    expect(parseDeepLink('https://mail.example.com/de/calendar/day/2026-02-03'))
+      .toEqual({ kind: 'calendar', view: 'day', date: '2026-02-03' });
+    expect(parseDeepLink('bulwarkmobile://calendar/agenda')).toEqual({ kind: 'calendar', view: 'agenda' });
+    expect(parseDeepLink('bulwarkmobile://calendar/tasks')).toEqual({ kind: 'calendar', view: 'tasks' });
+    // A bare date keeps the view on screen.
+    expect(parseDeepLink('bulwarkmobile://calendar/2026-08-06')).toEqual({ kind: 'calendar', date: '2026-08-06' });
+    // 2026-02-31 does not roll over into March.
+    expect(parseDeepLink('bulwarkmobile://calendar/month/2026-02-31')).toEqual({ kind: 'calendar', view: 'month' });
+    expect(parseDeepLink('bulwarkmobile://calendar/year/2026-08-06')).toEqual({ kind: 'calendar' });
+  });
+
+  it('reads the day as a local calendar day', () => {
+    const d = parseCalendarLinkDate('2026-08-06')!;
+    expect([d.getFullYear(), d.getMonth(), d.getDate(), d.getHours()]).toEqual([2026, 7, 6, 0]);
+    expect(parseCalendarLinkDate('2026-13-01')).toBeNull();
+    expect(parseCalendarLinkDate('06.08.2026')).toBeNull();
+  });
+
+  it('parks the view and day for the Calendar tab', async () => {
+    const navigation = nav();
+    const link = parseDeepLink('bulwarkmobile://calendar/day/2026-08-06')!;
+    expect(await handleDeepLink(link, { navigation: navigation as never, resolveThreadId: async () => null })).toBe(true);
+    expect(usePendingCalendarDate.getState().consume()).toEqual({ view: 'day', date: '2026-08-06' });
+    expect(usePendingCalendarOpen.getState().consume()).toBeNull();
+    expect(navigation.navigate).toHaveBeenCalledWith('MainTabs', { screen: 'Calendar' });
+
+    // A plain /calendar link parks nothing.
+    await handleDeepLink(parseDeepLink('bulwarkmobile://calendar')!, { navigation: navigation as never, resolveThreadId: async () => null });
+    expect(usePendingCalendarDate.getState().consume()).toBeNull();
+  });
+
+  // No RN renderer in the test env: check the screen's wiring instead.
+  it('is applied by the Calendar screen', () => {
+    const screen = fs.readFileSync(path.resolve(__dirname, '../../screens/CalendarScreen.tsx'), 'utf8');
+    expect(screen).toMatch(/const link = usePendingCalendarDate\.getState\(\)\.consume\(\);\s*if \(link\) applyDateLink\(link\);/);
+    expect(screen).toMatch(/const mode: ViewMode = link\.view && link\.view !== 'tasks' \? link\.view : viewMode;/);
+    expect(screen).toMatch(/setFocus\(\(prev\) => \(\{ date, nonce: prev\.nonce \+ 1 \}\)\);\s*setWindowState\(\(prev\) =>\s*mode === viewMode/);
+  });
+});

src/navigation/__tests__/linking.test.ts

@@ -22,7 +22,7 @@ describe('parseDeepLink', () => {
 
   it('parses calendar, contacts, files and settings links', () => {
     expect(parseDeepLink('bulwarkmobile://calendar/event/E1')).toEqual({ kind: 'calendar', eventId: 'E1' });
-    expect(parseDeepLink('bulwarkmobile://calendar/week/2026-08-29')).toEqual({ kind: 'calendar', date: '2026-08-29' });
+    expect(parseDeepLink('bulwarkmobile://calendar/week/2026-08-29')).toEqual({ kind: 'calendar', view: 'week', date: '2026-08-29' });
     expect(parseDeepLink('bulwarkmobile://contacts')).toEqual({ kind: 'contacts' });
     expect(parseDeepLink('bulwarkmobile://files')).toEqual({ kind: 'files' });
     expect(parseDeepLink('bulwarkmobile://settings/notifications')).toEqual({ kind: 'settings', tab: 'notifications' });
@@ -145,7 +145,7 @@ describe('handleDeepLink', () => {
     });
     expect(navigation.navigate).toHaveBeenCalledWith('MainTabs', { screen: 'Calendar' });
 
-    // A date or view link just opens the tab.
+    // A date or view link opens no event (calendar-date-link.test.ts).
     await handleDeepLink(
       { kind: 'calendar', date: '2026-08-29' },
       { navigation: navigation as never, resolveThreadId: async () => null },

src/navigation/linking.ts

@@ -8,6 +8,12 @@ import { parseMailtoUrl } from '../lib/mailto';
 import type { RootStackParamList } from './types';
 import { setPendingSettingsTab } from './pending-settings-tab';
 import { setPendingCalendarOpen } from './pending-calendar-open';
+import {
+  CALENDAR_LINK_VIEWS,
+  parseCalendarLinkDate,
+  setPendingCalendarDate,
+  type CalendarLinkView,
+} from './pending-calendar-date';
 import { setPendingMailSearch } from './pending-mail-search';
 import { setPendingMailFolder } from './pending-mail-folder';
 import { setPendingSignInLink, usePendingSignInLinkStore } from './pending-sign-in-link';
@@ -38,8 +44,9 @@ export type DeepLink =
   | { kind: 'search'; query: string }
   // `jmapAccountId`: the JMAP account owning the event (`?account=`), for
   // one on a calendar shared with the user; `accountId`: the signed-in
-  // account it belongs to (`?appAccount=`, from widgets).
-  | { kind: 'calendar'; eventId?: string; date?: string; jmapAccountId?: string; accountId?: string }
+  // account it belongs to (`?appAccount=`, from widgets). `view` and `date`
+  // (`YYYY-MM-DD`): the view and day a `/calendar/<view>/<date>` link shows.
+  | { kind: 'calendar'; eventId?: string; view?: CalendarLinkView; date?: string; jmapAccountId?: string; accountId?: string }
   | { kind: 'contact'; contactId: string }
   | { kind: 'contacts' }
   | { kind: 'files' }
@@ -149,8 +156,16 @@ export function parseDeepLink(url: string): DeepLink | null {
           ...(appAccountId ? { accountId: appAccountId } : {}),
         };
       }
-      const date = [kind, value].find((s) => s && /^\d{4}-\d{2}-\d{2}$/.test(s));
-      return { kind: 'calendar', date };
+      // `/calendar/<view>[/<date>]`, or a bare `/calendar/<date>` that keeps
+      // the view on screen (webmail parseCalendarPath).
+      if (kind && (CALENDAR_LINK_VIEWS as readonly string[]).includes(kind)) {
+        return {
+          kind: 'calendar',
+          view: kind as CalendarLinkView,
+          ...(parseCalendarLinkDate(value) ? { date: value } : {}),
+        };
+      }
+      return { kind: 'calendar', ...(parseCalendarLinkDate(kind) ? { date: kind } : {}) };
     }
     case 'contacts': {
       if (kind && kind !== 'new') return { kind: 'contact', contactId: decodeSegment(kind) };
@@ -298,6 +313,12 @@ export async function handleDeepLink(link: DeepLink, nav: DeepLinkNavigator): Pr
           serverId: link.eventId,
           accountId: link.jmapAccountId,
         });
+      } else if (link.view || link.date) {
+        // The Calendar tab moves to the view and day.
+        setPendingCalendarDate({
+          ...(link.view ? { view: link.view } : {}),
+          ...(link.date ? { date: link.date } : {}),
+        });
       }
       navigation.navigate('MainTabs', { screen: 'Calendar' } as never);
       return true;

src/navigation/pending-calendar-date.ts

@@ -0,0 +1,50 @@
+import { create } from 'zustand';
+
+/** The views a calendar link names (webmail lib/deep-links.ts CALENDAR_VIEWS). */
+export const CALENDAR_LINK_VIEWS = ['month', 'week', 'day', 'agenda', 'tasks'] as const;
+export type CalendarLinkView = typeof CALENDAR_LINK_VIEWS[number];
+
+/** A `/calendar/<view>/<yyyy-mm-dd>` link: the view and the day to show. */
+export interface CalendarDateLink {
+  view?: CalendarLinkView;
+  /** `YYYY-MM-DD`, a local calendar day. */
+  date?: string;
+}
+
+/**
+ * `YYYY-MM-DD` as a local-midnight Date; null when malformed or impossible
+ * (2026-02-31 would otherwise roll over into March). The webmail's
+ * parseLinkDate.
+ */
+export function parseCalendarLinkDate(value: string | null | undefined): Date | null {
+  const match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(value ?? '');
+  if (!match) return null;
+  const [, y, m, d] = match;
+  const date = new Date(Number(y), Number(m) - 1, Number(d));
+  if (Number.isNaN(date.getTime())) return null;
+  if (date.getMonth() !== Number(m) - 1 || date.getDate() !== Number(d)) return null;
+  return date;
+}
+
+// A date link arrives before CalendarScreen is mounted (cold start) or while
+// it shows another day. It is parked here and consumed by the screen, like
+// pending-calendar-open.
+interface PendingCalendarDateState {
+  link: CalendarDateLink | null;
+  set: (link: CalendarDateLink | null) => void;
+  consume: () => CalendarDateLink | null;
+}
+
+export const usePendingCalendarDate = create<PendingCalendarDateState>((set, get) => ({
+  link: null,
+  set: (link) => set({ link }),
+  consume: () => {
+    const link = get().link;
+    if (link) set({ link: null });
+    return link;
+  },
+}));
+
+export function setPendingCalendarDate(link: CalendarDateLink | null): void {
+  usePendingCalendarDate.getState().set(link);
+}

src/screens/CalendarScreen.tsx

@@ -107,6 +107,11 @@ import { useUserCalendarAddresses } from '../lib/calendar-user-addresses';
 import { useCalendarSubscriptionsStore } from '../stores/calendar-subscriptions-store';
 import { startCalendarNotificationSync } from '../lib/calendar-notifications';
 import { useCalendarReminderOpen } from '../lib/calendar-reminder-open';
+import {
+  parseCalendarLinkDate,
+  usePendingCalendarDate,
+  type CalendarDateLink,
+} from '../navigation/pending-calendar-date';
 import { shareEventICS } from '../lib/calendar-ics-export';
 import * as Clipboard from 'expo-clipboard';
 import type { Calendar, CalendarEvent } from '../api/types';
@@ -516,6 +521,42 @@ export default function CalendarScreen() {
     [viewMode, visibleDate, focus.date],
   );
 
+  // A `/calendar/<view>/<date>` link (webmail applyCalendarDeepLink): the
+  // view it names, on the day it names. Without a view the view on screen
+  // stays; `tasks`, a view the phone has as a sheet, opens the task list.
+  const applyDateLink = React.useCallback(
+    (link: CalendarDateLink) => {
+      if (link.view === 'tasks') {
+        if (enableCalendarTasks) {
+          setTasksInitialId(null);
+          setTasksVisible(true);
+        }
+      }
+      const mode: ViewMode = link.view && link.view !== 'tasks' ? link.view : viewMode;
+      const date = parseCalendarLinkDate(link.date);
+      if (!date) {
+        changeViewMode(mode);
+        return;
+      }
+      setSelectedDate(date);
+      setVisibleDate(null);
+      setFocus((prev) => ({ date, nonce: prev.nonce + 1 }));
+      setWindowState((prev) =>
+        mode === viewMode
+          ? windowStateForJump(prev, windowMode(mode), date, windowOptions)
+          : freshScrollWindowState(windowMode(mode), date),
+      );
+      setViewMode(mode);
+    },
+    [enableCalendarTasks, viewMode, changeViewMode, windowOptions],
+  );
+  const pendingDateLink = usePendingCalendarDate((s) => s.link);
+  React.useEffect(() => {
+    if (!pendingDateLink) return;
+    const link = usePendingCalendarDate.getState().consume();
+    if (link) applyDateLink(link);
+  }, [pendingDateLink, applyDateLink]);
+
   // The views, listed at the top of the drawer.
   const viewOptions = React.useMemo<DrawerViewOption[]>(
     () => [