fix: open the event a calendar link points at

src/navigation/__tests__/linking.test.ts

@@ -1,6 +1,7 @@
 import { describe, it, expect, vi } from 'vitest';
 import { handleDeepLink, parseDeepLink, shareToDeepLink } from '../linking';
 import { usePendingSettingsTab } from '../pending-settings-tab';
+import { usePendingCalendarOpen } from '../pending-calendar-open';
 
 describe('parseDeepLink', () => {
   it('parses app-scheme mail links', () => {
@@ -107,6 +108,28 @@ describe('handleDeepLink', () => {
     expect(navigation.navigate).not.toHaveBeenCalled();
   });
 
+  it('opens the event a calendar link names, also on a shared calendar', async () => {
+    const navigation = nav();
+    expect(parseDeepLink('https://mail.example.com/calendar/event/E1?account=acc-2'))
+      .toEqual({ kind: 'calendar', eventId: 'E1', jmapAccountId: 'acc-2' });
+
+    await handleDeepLink(
+      { kind: 'calendar', eventId: 'E1', jmapAccountId: 'acc-2' },
+      { navigation: navigation as never, resolveThreadId: async () => null },
+    );
+    expect(usePendingCalendarOpen.getState().consume()).toEqual({
+      kind: 'event', eventId: 'acc-2:E1', serverId: 'E1', accountId: 'acc-2',
+    });
+    expect(navigation.navigate).toHaveBeenCalledWith('MainTabs', { screen: 'Calendar' });
+
+    // A date or view link just opens the tab.
+    await handleDeepLink(
+      { kind: 'calendar', date: '2026-08-29' },
+      { navigation: navigation as never, resolveThreadId: async () => null },
+    );
+    expect(usePendingCalendarOpen.getState().consume()).toBeNull();
+  });
+
   it('parks the settings tab and opens the Settings tab', async () => {
     const navigation = nav();
     await handleDeepLink(

src/navigation/linking.ts

@@ -7,6 +7,7 @@ import type { EmailAddress } from '../api/types';
 import { parseMailtoUrl } from '../lib/mailto';
 import type { RootStackParamList } from './types';
 import { setPendingSettingsTab } from './pending-settings-tab';
+import { setPendingCalendarOpen } from './pending-calendar-open';
 
 export const APP_SCHEME = 'bulwarkmobile';
 
@@ -14,7 +15,9 @@ export type DeepLink =
   | { kind: 'message'; emailId: string; accountId?: string }
   | { kind: 'thread'; threadId: string; accountId?: string }
   | { kind: 'folder'; ref: string; accountId?: string }
-  | { kind: 'calendar'; eventId?: string; date?: string }
+  // `jmapAccountId`: the JMAP account owning the event (`?account=`), for
+  // one on a calendar shared with the user.
+  | { kind: 'calendar'; eventId?: string; date?: string; jmapAccountId?: string }
   | { kind: 'contact'; contactId: string }
   | { kind: 'contacts' }
   | { kind: 'files' }
@@ -88,7 +91,12 @@ export function parseDeepLink(url: string): DeepLink | null {
       return { kind: 'folder', ref: 'inbox', accountId };
     }
     case 'calendar': {
-      if (kind === 'event' && value) return { kind: 'calendar', eventId: decodeSegment(value) };
+      if (kind === 'event' && value) {
+        const jmapAccountId = search.get('account') ?? undefined;
+        return jmapAccountId
+          ? { kind: 'calendar', eventId: decodeSegment(value), jmapAccountId }
+          : { kind: 'calendar', eventId: decodeSegment(value) };
+      }
       const date = [kind, value].find((s) => s && /^\d{4}-\d{2}-\d{2}$/.test(s));
       return { kind: 'calendar', date };
     }
@@ -154,6 +162,16 @@ export async function handleDeepLink(link: DeepLink, nav: DeepLinkNavigator): Pr
       navigation.navigate('MainTabs', { screen: 'Mail' } as never);
       return true;
     case 'calendar':
+      // An event link opens the event like a tapped reminder does: the
+      // Calendar tab looks it up by its server id.
+      if (link.eventId) {
+        setPendingCalendarOpen({
+          kind: 'event',
+          eventId: link.jmapAccountId ? `${link.jmapAccountId}:${link.eventId}` : link.eventId,
+          serverId: link.eventId,
+          accountId: link.jmapAccountId,
+        });
+      }
       navigation.navigate('MainTabs', { screen: 'Calendar' } as never);
       return true;
     case 'contact':