diff --git a/calendar-agenda/calendar-agenda.zip b/calendar-agenda/calendar-agenda.zip
index 5a82da2..f444ffc 100644
Binary files a/calendar-agenda/calendar-agenda.zip and b/calendar-agenda/calendar-agenda.zip differ
diff --git a/calendar-agenda/manifest.json b/calendar-agenda/manifest.json
index 3ac4e3f..903b0d8 100644
--- a/calendar-agenda/manifest.json
+++ b/calendar-agenda/manifest.json
@@ -1,7 +1,7 @@
 {
   "id": "calendar-agenda",
   "name": "Calendar Agenda",
-  "version": "1.4.3",
+  "version": "1.4.4",
   "author": "Bulwark Mail Community",
   "description": "Shows an agenda of your upcoming calendar events in the sidebar.",
   "type": "sidebar-app",
@@ -12,7 +12,7 @@
     "ui:app-top-banner"
   ],
   "entrypoint": "index.js",
-  "minAppVersion": "1.15.0",
+  "minAppVersion": "1.18.0",
   "icon": "media/icon.svg",
   "banner": "media/banner.svg",
   "settingsSchema": {
diff --git a/calendar-agenda/package.json b/calendar-agenda/package.json
index c6f19de..f8a8dbe 100644
--- a/calendar-agenda/package.json
+++ b/calendar-agenda/package.json
@@ -1,6 +1,6 @@
 {
   "name": "bulwark-plugin-calendar-agenda",
-  "version": "1.4.3",
+  "version": "1.4.4",
   "private": true,
   "type": "module",
   "scripts": {
diff --git a/calendar-agenda/src/lib/agenda.js b/calendar-agenda/src/lib/agenda.js
index 1d77497..a5ab153 100644
--- a/calendar-agenda/src/lib/agenda.js
+++ b/calendar-agenda/src/lib/agenda.js
@@ -52,7 +52,7 @@ export function durationMs(duration) {
  * event's `start` is wall-clock time in its own zone, so its UTC start
  * places it; an all-day event starts at local midnight.
  */
-export function toAgendaEvent(view, untitled, colors = new Map()) {
+export function toAgendaEvent(view, untitled = '', colors = new Map()) {
   const allDay = !!view.isAllDay;
   const start = !allDay && view.utcStart ? new Date(view.utcStart) : new Date(view.start);
   const end = !allDay && view.utcEnd ? new Date(view.utcEnd) : new Date(start.getTime() + durationMs(view.duration));
@@ -117,17 +117,23 @@ export function groupByDay(events, now = new Date()) {
 
 export function makeFormat(api, now = () => new Date()) {
   const t = (key, vars) => api.i18n.t(key, vars);
-  const locale = () => api.i18n.locale || (api.i18n.getLocale && api.i18n.getLocale()) || undefined;
+  const locale = () => api.i18n.dateLocale || api.i18n.locale || (api.i18n.getLocale && api.i18n.getLocale()) || undefined;
 
   function dayLabel(date) {
     const diffDays = Math.round((startOfDay(date).getTime() - startOfDay(now()).getTime()) / 86_400_000);
     if (diffDays === 0) return t('day.today');
     if (diffDays === 1) return t('day.tomorrow');
+    if (typeof api.i18n?.formatDate === 'function') {
+      return api.i18n.formatDate(date, { weekday: 'short', month: 'short', day: 'numeric' });
+    }
     return date.toLocaleDateString(locale(), { weekday: 'short', month: 'short', day: 'numeric' });
   }
 
   function timeLabel(ev) {
     if (ev.allDay) return t('event.all_day');
+    if (typeof api.i18n?.formatTime === 'function') {
+      return api.i18n.formatTime(ev.start, { hour: '2-digit', minute: '2-digit' });
+    }
     return new Date(ev.start).toLocaleTimeString(locale(), { hour: '2-digit', minute: '2-digit' });
   }
 
@@ -147,9 +153,10 @@ export function makeAgenda(React, api, { slot = DEFAULT_SLOT, now } = {}) {
   const fmt = makeFormat(api, now);
   const { t } = fmt;
 
-  // A cancelled event keeps its row, struck through.
-  const titleOf = (ev) => (ev.status === 'cancelled' ? h('del', null, ev.title) : ev.title);
-  const tooltip = (ev) => [ev.title, fmt.when(ev), ev.location].filter(Boolean).join(' · ');
+  // A cancelled event keeps its row, struck through. Fall back to "(No title)" if title is blank.
+  const titleTextOf = (ev) => ev.title || t('event.untitled');
+  const titleOf = (ev) => (ev.status === 'cancelled' ? h('del', null, titleTextOf(ev)) : titleTextOf(ev));
+  const tooltip = (ev) => [titleTextOf(ev), fmt.when(ev), ev.location].filter(Boolean).join(' · ');
 
   function useAgenda() {
     const [events, setEvents] = useState([]);
@@ -167,7 +174,7 @@ export function makeAgenda(React, api, { slot = DEFAULT_SLOT, now } = {}) {
       if (inFlightRef.current) return;
       inFlightRef.current = true;
       try {
-        setEvents(await loadAgenda(api, { days, limit, now: now ? now() : new Date(), untitled: t('event.untitled') }));
+        setEvents(await loadAgenda(api, { days, limit, now: now ? now() : new Date() }));
         setState('ready');
       } catch (err) {
         const text = String((err && err.message) || err);
@@ -268,7 +275,7 @@ export function makeAgenda(React, api, { slot = DEFAULT_SLOT, now } = {}) {
     const { events, message } = useAgenda();
     return h(InfoBar, { compact: true, tone: 'primary', icon: 'calendar', eyebrow: t('header.title'), title: message || undefined },
       ...(message ? [] : events.slice(0, BANNER_EVENTS).map((ev) => h(Chip, {
-        key: ev.id, label: h(React.Fragment, null, chipDot(ev), ev.title), detail: fmt.when(ev), title: tooltip(ev),
+        key: ev.id, label: h(React.Fragment, null, chipDot(ev), titleOf(ev)), detail: fmt.when(ev), title: tooltip(ev),
       }))),
       !message && events.length > BANNER_EVENTS ? h(Text, { key: 'more', size: 'xs', tone: 'muted' }, `+${events.length - BANNER_EVENTS}`) : null);
   }
diff --git a/calendar-agenda/test/agenda.test.mjs b/calendar-agenda/test/agenda.test.mjs
index 1eeb1bc..569b4fd 100644
--- a/calendar-agenda/test/agenda.test.mjs
+++ b/calendar-agenda/test/agenda.test.mjs
@@ -41,9 +41,22 @@ const events = [
 
 const calendars = [{ id: 'cal', name: 'Work', color: '#3b82f6', isVisible: true, isDefault: true, isTasksOnly: false }];
 
-function setup(slot, { getEvents = async () => events, listCalendars = async () => calendars, settings = { daysAhead: 7 } } = {}) {
+function setup(slot, {
+  getEvents = async () => events,
+  listCalendars = async () => calendars,
+  settings = { daysAhead: 7 },
+  locale = 'en',
+  dateLocale,
+  timeFormat,
+  timeZone,
+} = {}) {
   const api = fakeApi({
-    translations: manifest.locales, settings,
+    translations: manifest.locales,
+    settings,
+    locale,
+    dateLocale,
+    timeFormat,
+    timeZone,
     handlers: { 'calendar.getEvents': getEvents, 'calendar.listCalendars': listCalendars },
   });
   const Agenda = makeAgenda(React, api, { slot, now: NOW });
@@ -224,3 +237,43 @@ describe('reading pane and top banner', () => {
     expect(bar.querySelectorAll('span[title]')).toHaveLength(3);
   });
 });
+
+describe('regional formatting and locale settings', () => {
+  it('formats times in 24h when timeFormat is 24h', async () => {
+    const { Agenda } = setup('sidebar-section', {
+      timeFormat: '24h',
+      getEvents: async () => [timed('a', 'Afternoon Meeting', new Date(2026, 9, 14, 14, 30), 30)],
+    });
+    await show(Agenda);
+    expect(document.body.textContent).toContain('Afternoon Meeting14:30');
+  });
+
+  it('formats times in 12h when timeFormat is 12h', async () => {
+    const { Agenda } = setup('sidebar-section', {
+      timeFormat: '12h',
+      getEvents: async () => [timed('a', 'Afternoon Meeting', new Date(2026, 9, 14, 14, 30), 30)],
+    });
+    await show(Agenda);
+    expect(document.body.textContent).toMatch(/Afternoon Meeting(2:30|02:30)\s*PM/);
+  });
+
+  it('formats date headings using dateLocale when provided', async () => {
+    const { Agenda } = setup('sidebar-section', {
+      dateLocale: 'de',
+      getEvents: async () => [allDay('n', 'Future', '2026-10-18')],
+    });
+    await show(Agenda);
+    const headings = dayHeadings();
+    // 'de' locale short weekday for Sunday is 'So.'
+    expect(headings.some((h) => h.includes('So.'))).toBe(true);
+  });
+
+  it('resolves untitled fallback dynamically in the active locale', async () => {
+    const { Agenda } = setup('sidebar-section', {
+      locale: 'de',
+      getEvents: async () => [timed('x', '', new Date(2026, 9, 14, 11, 0), 30)],
+    });
+    await show(Agenda);
+    expect(rowTitles()).toEqual(['(Kein Titel)']);
+  });
+});
diff --git a/test-utils/fake-api.mjs b/test-utils/fake-api.mjs
index 199ccc9..a85c066 100644
--- a/test-utils/fake-api.mjs
+++ b/test-utils/fake-api.mjs
@@ -12,12 +12,27 @@
 // the call and returns what `handlers['anything.method']` returns (undefined
 // without a handler). storage, i18n and plugin.settings work for real.
 
-export function fakeApi({ id = 'test-plugin', version = '1.0.0', settings = {}, locale = 'en', translations = {}, handlers = {} } = {}) {
+export function fakeApi({
+  id = 'test-plugin',
+  version = '1.0.0',
+  settings = {},
+  locale = 'en',
+  dateLocale,
+  timeFormat,
+  timeZone,
+  firstDayOfWeek = 1,
+  translations = {},
+  handlers = {},
+} = {}) {
   const log = [];
   const store = new Map();
   const settingsListeners = [];
   const localeListeners = [];
   let currentLocale = locale;
+  let currentDateLocale = dateLocale;
+  let currentTimeFormat = timeFormat;
+  let currentTimeZone = timeZone;
+  let currentFirstDayOfWeek = firstDayOfWeek;
 
   const call = (method, args) => {
     log.push({ method, args });
@@ -34,6 +49,20 @@ export function fakeApi({ id = 'test-plugin', version = '1.0.0', settings = {},
     return undefined;
   };
 
+  const formatIntl = (date, options = {}) => {
+    try {
+      const d = date instanceof Date ? date : new Date(date);
+      if (isNaN(d.getTime())) return '';
+      const opts = {
+        ...(currentTimeZone ? { timeZone: currentTimeZone } : {}),
+        ...options,
+      };
+      return new Intl.DateTimeFormat(currentDateLocale ?? currentLocale, opts).format(d);
+    } catch {
+      return '';
+    }
+  };
+
   const known = {
     plugin: {
       // Same shape as the real api.plugin: no permission list.
@@ -49,6 +78,19 @@ export function fakeApi({ id = 'test-plugin', version = '1.0.0', settings = {},
       keys: async () => [...store.keys()],
     },
     i18n: {
+      get locale() { return currentLocale; },
+      get dateLocale() { return currentDateLocale ?? currentLocale; },
+      get timeFormat() { return currentTimeFormat ?? (new Intl.DateTimeFormat(currentDateLocale ?? currentLocale, { hour: 'numeric' }).resolvedOptions().hour12 ? '12h' : '24h'); },
+      get hour12() { return currentTimeFormat ? currentTimeFormat === '12h' : (new Intl.DateTimeFormat(currentDateLocale ?? currentLocale, { hour: 'numeric' }).resolvedOptions().hour12 ?? false); },
+      get timeZone() { return currentTimeZone ?? (Intl.DateTimeFormat().resolvedOptions().timeZone || 'UTC'); },
+      get firstDayOfWeek() { return currentFirstDayOfWeek; },
+      formatTime: (date, options = {}) => formatIntl(date, {
+        hour: '2-digit',
+        minute: '2-digit',
+        ...(currentTimeFormat ? { hour12: currentTimeFormat === '12h' } : {}),
+        ...options,
+      }),
+      formatDate: (date, options = {}) => formatIntl(date, options),
       t(key, vars) {
         const text = lookup(key) ?? key;
         return text.replace(/\{(\w+)\}/g, (m, name) => (vars && name in vars ? String(vars[name]) : m));
@@ -70,7 +112,15 @@ export function fakeApi({ id = 'test-plugin', version = '1.0.0', settings = {},
   const api = new Proxy(known, {
     get(target, name) {
       if (name === 'calls') return (method) => (method ? log.filter((c) => c.method === method) : [...log]);
-      if (name === 'setLocale') return (l) => { currentLocale = l; for (const fn of localeListeners) fn(l); };
+      if (name === 'setLocale') return (l, regional = {}) => {
+        currentLocale = l;
+        if (regional.dateLocale !== undefined) currentDateLocale = regional.dateLocale;
+        if (regional.hour12 !== undefined) currentTimeFormat = regional.hour12 ? '12h' : '24h';
+        if (regional.timeFormat !== undefined) currentTimeFormat = regional.timeFormat;
+        if (regional.timeZone !== undefined) currentTimeZone = regional.timeZone;
+        if (regional.firstDayOfWeek !== undefined) currentFirstDayOfWeek = regional.firstDayOfWeek;
+        for (const fn of localeListeners) fn(l);
+      };
       if (name === 'changeSettings') return (next) => { Object.assign(target.plugin.settings, next); for (const fn of settingsListeners) fn({ ...target.plugin.settings }); };
       if (name === 'storageSnapshot') return () => Object.fromEntries(store);
       if (typeof name !== 'string') return undefined;