fix: translate the no-subject fallback in mail lists and notifications

The mail list, the unified inbox, a contact's recent emails and new-mail
notifications showed a hard-coded English "(no subject)". They now use
the webmail's `email_viewer.no_subject` (and `contacts.activity.no_subject`
for the contact view). The notification task reads the in-app language
override itself, as it cannot use the locale store.

src/components/contacts/ContactActivity.tsx

@@ -9,6 +9,7 @@ import type { RootStackParamList } from '../../navigation/types';
 import { getEmails, queryEmailsByFilter } from '../../api/email';
 import { getEvents, queryEvents } from '../../api/calendar';
 import { useCalendarStore } from '../../stores/calendar-store';
+import { useLocaleStore } from '../../stores/locale-store';
 import { getEventColor } from '../../lib/calendar-utils';
 import { hasCalendarCapability } from '../../lib/capabilities';
 import SenderAvatar from '../SenderAvatar';
@@ -90,6 +91,7 @@ export function ContactActivity({ contact }: Props) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
   const navigation = useNavigation<Nav>();
+  const t = useLocaleStore((s) => s.t);
   const calendarEvents = useCalendarStore((s) => s.events);
   const calendars = useCalendarStore((s) => s.calendars);
 
@@ -219,7 +221,7 @@ export function ContactActivity({ contact }: Props) {
                       <Text style={styles.rowDate}>{formatRelativeDate(email.receivedAt)}</Text>
                     </View>
                     <Text style={styles.rowSubject} numberOfLines={1}>
-                      {email.subject || '(no subject)'}
+                      {email.subject || t('contacts.activity.no_subject', '(No subject)')}
                     </Text>
                     {email.preview ? (
                       <Text style={styles.rowPreview} numberOfLines={1}>{email.preview}</Text>

src/lib/__tests__/push-background-task.test.ts

@@ -155,6 +155,35 @@ describe('pushBackgroundTask notifications', () => {
       expect.objectContaining({ emailId: 'm1', accountId: LOCAL, jmapAccountId: 'jmap-primary' }),
     );
   });
+
+  it("says a message has no subject in the app's language", async () => {
+    await AsyncStorage.setItem('webmail:locale:v1', JSON.stringify({ override: 'de' }));
+    (secureFetch as ReturnType<typeof vi.fn>).mockImplementation(async (url: string) => ({
+      ok: true,
+      json: async () => (url.endsWith('/.well-known/jmap')
+        ? {
+          apiUrl: 'https://mail.example.com/jmap/',
+          primaryAccounts: { 'urn:ietf:params:jmap:mail': 'jmap-primary' },
+          accounts: { 'jmap-primary': {} },
+        }
+        : {
+          methodResponses: [[
+            'Email/get',
+            { list: [{ id: 'm1', threadId: 't1', keywords: {}, subject: '', from: [{ email: 'bob@example.com' }] }] },
+            '0',
+          ]],
+        }),
+    }));
+
+    await pushBackgroundTask({
+      kind: 'jmap-email-push',
+      accountLabel: 'alice',
+      accountId: 'jmap-primary',
+      emailIds: JSON.stringify(['m1']),
+    });
+
+    expect(showNotification).toHaveBeenCalledWith(expect.objectContaining({ emailId: 'm1', body: '(Kein Betreff)' }));
+  });
 });
 
 describe('selectNotifiableEmails', () => {

src/lib/push-background-task.ts

@@ -3,6 +3,7 @@ import { NativeModules } from 'react-native';
 import { jmapClient, type StoredCredentials } from '../api/jmap-client';
 import { CAPABILITIES } from '../api/types';
 import type { Email, JMAPMethodCall, JMAPSession, Mailbox } from '../api/types';
+import { detectDeviceLocale, isSupportedLocale, translate, type LocaleCode } from '../i18n';
 import { secureFetch } from './client-cert';
 import { refreshOAuthAccessToken, type OAuthTokens } from './oauth';
 import {
@@ -23,6 +24,8 @@ import {
 // import the Zustand store (would pull in React) so we read AsyncStorage
 // directly. Keep this in sync if the store key ever changes.
 const SETTINGS_STORAGE_KEY = 'webmail:settings:v1';
+// Mirrors STORAGE_KEY in `stores/locale-store.ts`, for the same reason.
+const LOCALE_STORAGE_KEY = 'webmail:locale:v1';
 // Mirrors the persist name in `stores/account-store.ts`. Used to map the
 // relay's `accountLabel` (= username) back to a local account when the JMAP
 // account id is not known yet.
@@ -70,6 +73,16 @@ export async function senderFaviconsAllowed(): Promise<boolean> {
   }
 }
 
+/** The app's language: the in-app override, else the device's. */
+export async function notificationLocale(): Promise<LocaleCode> {
+  try {
+    const raw = await AsyncStorage.getItem(LOCALE_STORAGE_KEY);
+    const override = raw ? (JSON.parse(raw) as { override?: unknown }).override : null;
+    if (typeof override === 'string' && isSupportedLocale(override)) return override;
+  } catch { /* the device language it is */ }
+  return detectDeviceLocale();
+}
+
 interface ShowNotificationOptions {
   notificationId: string;
   title: string;
@@ -449,6 +462,7 @@ async function processAccountForPush(accountId: string, payload: RelayPushData):
   const groupKey = `bulwark-mail:${accountId}`;
   const groupTitle = payload.accountLabel ?? accountId.split('@')[0] ?? accountId;
   const favicons = await senderFaviconsAllowed();
+  const locale = await notificationLocale();
 
   // Oldest first so the newest ends up on top of the tray.
   const ordered = [...toNotify].sort(
@@ -459,7 +473,7 @@ async function processAccountForPush(accountId: string, payload: RelayPushData):
     const name = from?.name ?? '';
     const address = from?.email ?? '';
     const title = name || address || 'New mail';
-    const body = email.subject || '(no subject)';
+    const body = email.subject || translate(locale, 'email_viewer.no_subject', '(No Subject)');
     const initials = getEmailInitials(name, address);
     const bgColorHex = hslToHex(generateEmailAvatarColor(name, address));
     const faviconDomain = favicons ? getFaviconDomain(address) : null;

src/screens/EmailListScreen.tsx

@@ -219,7 +219,7 @@ const EmailRow = React.memo(function EmailRow({
         {/* Row 2: Subject + tag pills */}
         <View style={styles.subjectRow}>
           <Text style={[styles.emailSubject, dyn.body, unread && styles.textBold]} numberOfLines={1}>
-            {singleLine(item.subject) || '(no subject)'}
+            {singleLine(item.subject) || tr('email_viewer.no_subject', '(No Subject)')}
           </Text>
           {tags.slice(0, 3).map((tag) => (
             <View key={tag.id} style={[styles.tagPill, { backgroundColor: tag.bg }]}>

src/screens/UnifiedInboxScreen.tsx

@@ -320,7 +320,7 @@ export default function UnifiedInboxScreen({ navigation, route }: Props) {
               <Text style={styles.time}>{formatListDate(item.receivedAt, { dateFormat, timeFormat, locale, t })}</Text>
             </View>
             <Text style={[styles.subject, unread && styles.bold]} numberOfLines={1}>
-              {singleLine(item.subject) || '(no subject)'}
+              {singleLine(item.subject) || t('email_viewer.no_subject', '(No Subject)')}
             </Text>
             <View style={styles.line}>
               {acc && accountIds.length > 1 && (