feat: offer to remove a cancelled meeting from the calendar in the cancellation mail #1425

components/email/__tests__/calendar-invitation-banner.test.tsx

@@ -11,7 +11,7 @@ const mocks = vi.hoisted(() => {
     getAccountId: vi.fn(() => 'mail-account'),
     getCalendarsAccountId: vi.fn(() => 'calendar-account'),
     getCalendarEvent: vi.fn(),
-    queryCalendarEvents: vi.fn(async () => []),
+    queryCalendarEvents: vi.fn(async (): Promise<unknown[]> => []),
   };
 
   const sourceClientMock = {
@@ -45,6 +45,7 @@ const mocks = vi.hoisted(() => {
     importEvents: vi.fn(),
     rsvpEvent: vi.fn(),
     updateEvent: vi.fn(),
+    deleteEvent: vi.fn(),
     events: [] as Array<Record<string, unknown>>,
     setSelectedDate: vi.fn(),
   };
@@ -186,6 +187,7 @@ describe('CalendarInvitationBanner', () => {
     mocks.calendarState.importEvents.mockReset();
     mocks.calendarState.rsvpEvent.mockReset();
     mocks.calendarState.updateEvent.mockReset();
+    mocks.calendarState.deleteEvent.mockReset();
     mocks.calendarState.setSelectedDate.mockReset();
     mocks.calendarState.events = [];
     mocks.sourceClientMock.parseCalendarEvents.mockReset();
@@ -1094,4 +1096,99 @@ describe('CalendarInvitationBanner', () => {
       });
     });
   });
+  describe('cancellations (#1425)', () => {
+    const ORGANIZER = {
+      '@type': 'Participant', email: 'boss@example.com', calendarAddress: 'mailto:boss@example.com',
+      roles: { owner: true }, participationStatus: 'accepted',
+    };
+    const ME = {
+      '@type': 'Participant', email: 'user@example.com', calendarAddress: 'mailto:user@example.com',
+      roles: { attendee: true }, participationStatus: 'accepted',
+    };
+    const cancelEmail = (overrides: Partial<Email> = {}) => makeEmail({
+      id: 'email-cancel',
+      from: [{ email: 'boss@example.com', name: 'Boss' }],
+      attachments: [{ partId: '1', blobId: 'blob-c', size: 256, type: 'text/calendar; method=CANCEL', name: 'cancel.ics' }],
+      ...overrides,
+    });
+    const parsedCancel = (overrides: Record<string, unknown> = {}) => ({
+      uid: 'uid-c', title: 'Planning', start: '2026-11-02T10:00:00', timeZone: 'Europe/Berlin', duration: 'PT1H',
+      status: 'cancelled', sequence: 2, organizerCalendarAddress: 'mailto:boss@example.com',
+      participants: { organizer: ORGANIZER, me: ME },
+      ...overrides,
+    });
+    const storedEvent = (overrides: Record<string, unknown> = {}) => ({
+      id: 'ev-c', uid: 'uid-c', title: 'Planning', start: '2026-11-02T10:00:00', timeZone: 'Europe/Berlin',
+      duration: 'PT1H', sequence: 2, status: 'cancelled', recurrenceId: null, recurrenceRules: null,
+      recurrenceOverrides: null, participants: { organizer: ORGANIZER, me: ME },
+      ...overrides,
+    });
+
+    it('removes the cancelled meeting from the calendar without telling anyone', async () => {
+      mocks.clientMock.parseCalendarEvents.mockResolvedValue([parsedCancel()]);
+      mocks.clientMock.queryCalendarEvents.mockResolvedValue([storedEvent()]);
+      mocks.calendarState.events = [storedEvent()];
+      mocks.calendarState.deleteEvent.mockResolvedValue(true);
+
+      render(<CalendarInvitationBanner email={cancelEmail()} />);
+      fireEvent.click(await screen.findByText('remove_from_calendar'));
+
+      await waitFor(() => expect(screen.getByText('removed_from_calendar')).toBeInTheDocument());
+      expect(mocks.clientMock.queryCalendarEvents).toHaveBeenCalledWith({ uid: 'uid-c' });
+      expect(mocks.calendarState.deleteEvent).toHaveBeenCalledWith(mocks.clientMock, 'ev-c', false);
+      expect(mocks.calendarState.events).toEqual([]);
+      expect(screen.queryByText('remove_from_calendar')).not.toBeInTheDocument();
+    });
+
+    it('takes only the cancelled occurrence out of a series', async () => {
+      const series = storedEvent({ recurrenceRules: [{ '@type': 'RecurrenceRule', frequency: 'weekly' }], status: 'confirmed' });
+      mocks.clientMock.parseCalendarEvents.mockResolvedValue([parsedCancel({
+        start: '2026-11-09T10:00:00', recurrenceId: '2026-11-09T10:00:00', recurrenceIdTimeZone: 'Europe/Berlin',
+      })]);
+      mocks.clientMock.queryCalendarEvents.mockResolvedValue([series]);
+      mocks.calendarState.events = [series];
+      mocks.calendarState.updateEvent.mockResolvedValue(true);
+
+      render(<CalendarInvitationBanner email={cancelEmail()} />);
+      fireEvent.click(await screen.findByText('remove_from_calendar'));
+
+      await waitFor(() => expect(screen.getByText('removed_from_calendar')).toBeInTheDocument());
+      expect(mocks.calendarState.updateEvent).toHaveBeenCalledWith(
+        mocks.clientMock, 'ev-c', { recurrenceOverrides: { '2026-11-09T10:00:00': { excluded: true } } }, false,
+      );
+      expect(mocks.calendarState.deleteEvent).not.toHaveBeenCalled();
+    });
+
+    it('does not offer to remove a meeting the calendar holds a newer version of', async () => {
+      mocks.clientMock.parseCalendarEvents.mockResolvedValue([parsedCancel({ sequence: 1 })]);
+      mocks.clientMock.queryCalendarEvents.mockResolvedValue([storedEvent({ sequence: 3, status: 'confirmed' })]);
+
+      render(<CalendarInvitationBanner email={cancelEmail()} />);
+
+      expect(await screen.findByText('cancel_outdated')).toBeInTheDocument();
+      expect(screen.queryByText('remove_from_calendar')).not.toBeInTheDocument();
+    });
+
+    it('does not offer it for an unverified cancellation from someone other than the organizer', async () => {
+      mocks.clientMock.parseCalendarEvents.mockResolvedValue([parsedCancel()]);
+      mocks.clientMock.queryCalendarEvents.mockResolvedValue([storedEvent()]);
+
+      render(<CalendarInvitationBanner email={cancelEmail({ from: [{ email: 'mallory@evil.example', name: 'Mallory' }] })} />);
+
+      await screen.findByText(/could not be verified/);
+      await waitFor(() => expect(mocks.clientMock.queryCalendarEvents).toHaveBeenCalledWith({ uid: 'uid-c' }));
+      expect(screen.queryByText('remove_from_calendar')).not.toBeInTheDocument();
+    });
+
+    it('does not offer it when the meeting is not in the calendar', async () => {
+      mocks.clientMock.parseCalendarEvents.mockResolvedValue([parsedCancel()]);
+      mocks.clientMock.queryCalendarEvents.mockResolvedValue([]);
+
+      render(<CalendarInvitationBanner email={cancelEmail()} />);
+
+      await screen.findByRole('heading', { name: 'Planning' });
+      await waitFor(() => expect(mocks.clientMock.queryCalendarEvents).toHaveBeenCalledWith({ uid: 'uid-c' }));
+      expect(screen.queryByText('remove_from_calendar')).not.toBeInTheDocument();
+    });
+  });
 });

components/email/calendar-invitation-banner.tsx

@@ -41,7 +41,7 @@ import {
   type InvitationTrustAssessment,
 } from '@/lib/calendar-invitation';
 import { participantsAskedAgain } from '@/lib/calendar-participants';
-import { isValidTimeZone, moveLocalDateTime } from '@/lib/timezone';
+import { planCancellationRemoval, sameRecurrenceId, type CancellationRemoval } from '@/lib/calendar-cancellation';
 import { cn } from '@/lib/utils';
 import { getEventStartDate } from '@/lib/calendar-utils';
 import { sanitizeColor } from '@/components/calendar/event-card';
@@ -223,17 +223,6 @@ function getViewActionLabel(
   return t('view_in_calendar');
 }
 
-/** Whether two events name the same occurrence: their recurrence ids at the same moment, each in its own zone. */
-function sameRecurrenceId(a: Partial<CalendarEvent>, b: Partial<CalendarEvent>): boolean {
-  if (!a.recurrenceId || !b.recurrenceId) return false;
-  const zoneA = a.recurrenceIdTimeZone ?? a.timeZone ?? null;
-  const zoneB = b.recurrenceIdTimeZone ?? b.timeZone ?? null;
-  const bInA = zoneA && zoneB && isValidTimeZone(zoneA) && isValidTimeZone(zoneB)
-    ? moveLocalDateTime(b.recurrenceId.slice(0, 19), zoneB, zoneA)
-    : b.recurrenceId;
-  return a.recurrenceId.slice(0, 19) === bInA.slice(0, 19);
-}
-
 /**
  * The event in the calendar a counter proposal is about. An attendee's
  * proposal for one occurrence of a recurring meeting names that occurrence
@@ -439,12 +428,13 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
   }));
   const calendarInvitationParsingEnabled = useSettingsStore((s) => s.calendarInvitationParsingEnabled);
   const timeFormat = useSettingsStore((s) => s.timeFormat);
-  const { calendars, supportsCalendar, importEvents, rsvpEvent, updateEvent, events: storeEvents, setSelectedDate } = useCalendarStore(useShallow((state) => ({
+  const { calendars, supportsCalendar, importEvents, rsvpEvent, updateEvent, deleteEvent, events: storeEvents, setSelectedDate } = useCalendarStore(useShallow((state) => ({
     calendars: state.calendars,
     supportsCalendar: state.supportsCalendar,
     importEvents: state.importEvents,
     rsvpEvent: state.rsvpEvent,
     updateEvent: state.updateEvent,
+    deleteEvent: state.deleteEvent,
     events: state.events,
     setSelectedDate: state.setSelectedDate,
   })));
@@ -464,6 +454,9 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
   // Underlying failure shown under the generic parse error, so "wrong account"
   // or a network failure is distinguishable from an unparsable file.
   const [parseError, setParseError] = useState<string | null>(null);
+  // What removing a cancelled meeting from the calendar takes, read from the
+  // events stored with its uid; null until known.
+  const [cancelRemoval, setCancelRemoval] = useState<CancellationRemoval | null>(null);
 
   const attachment = findCalendarAttachment(email);
 
@@ -555,12 +548,25 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
     };
   }, [showCalendarPicker]);
 
+  const detectedMethod = parsedEvent && attachment ? getInvitationMethod(parsedEvent, { email, attachment }) : 'unknown';
+  const method = detectedMethod !== 'unknown' ? detectedMethod : rawIcsMethod;
+  const isCancellation = method === 'cancel';
+
+  useEffect(() => {
+    setCancelRemoval(null);
+    if (!client || !supportsCalendar || !isCancellation || !parsedEvent?.uid) return;
+    let current = true;
+    client.queryCalendarEvents({ uid: parsedEvent.uid })
+      .then((stored) => {
+        if (current) setCancelRemoval(planCancellationRemoval(stored, parsedEvent));
+      })
+      .catch(() => { /* no remove action then */ });
+    return () => { current = false; };
+  }, [client, supportsCalendar, isCancellation, parsedEvent]);
+
   if (!attachment || !calendarInvitationParsingEnabled) return null;
 
-  const detectedMethod = parsedEvent ? getInvitationMethod(parsedEvent, { email, attachment }) : 'unknown';
-  const method = detectedMethod !== 'unknown' ? detectedMethod : rawIcsMethod;
   const summary = parsedEvent ? formatEventSummary(parsedEvent) : null;
-  const isCancellation = method === 'cancel';
   const isResponseOnly = method === 'reply' || method === 'refresh' || method === 'counter' || method === 'declinecounter';
   const showDetails = !isCollapsed;
   const allowsRsvp = method === 'request';
@@ -616,6 +622,17 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
   const proposalFromParticipant = Boolean(
     proposalTarget && senderAddress && findParticipantByEmails(proposalTarget, [senderAddress]),
   );
+  // A cancellation that fails authentication, or comes from someone other
+  // than the organizer without passing it, does not get to remove anything.
+  const canRemoveCancelled = Boolean(
+    client
+    && supportsCalendar
+    && isCancellation
+    && !userIsSender
+    && trustAssessment?.level !== 'warning'
+    && (cancelRemoval?.kind === 'delete' || cancelRemoval?.kind === 'exclude')
+  );
+  const cancellationOutdated = isCancellation && cancelRemoval?.kind === 'outdated';
 
   const resolveExistingEventForRsvp = async () => {
     if (!client || !existingEvent) {
@@ -811,6 +828,42 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
     }
   };
 
+  const handleRemoveCancelled = async () => {
+    const cancel = parsedEvent;
+    if (!client || !cancel?.uid || isProcessing) return;
+    setActionNotice(null);
+    setActionError(null);
+    setIsProcessing(true);
+    try {
+      // Planned again on the events as they are now: the calendar may have
+      // changed since the mail was opened.
+      const removal = planCancellationRemoval(await client.queryCalendarEvents({ uid: cancel.uid }), cancel);
+      setCancelRemoval(removal);
+      // No scheduling messages: the organizer cancelled it, there is no one
+      // to tell.
+      if (removal.kind === 'delete') {
+        for (const id of removal.ids) {
+          if (!(await deleteEvent(client, id, false))) return;
+        }
+      } else if (removal.kind === 'exclude') {
+        if (!(await updateEvent(client, removal.id, removal.patch, false))) return;
+      } else {
+        return;
+      }
+      // Occurrences of it in view go as well.
+      useCalendarStore.setState((s) => ({
+        events: s.events.filter((event) => event.uid !== cancel.uid
+          || (Boolean(cancel.recurrenceId) && !sameRecurrenceId(event, cancel))),
+      }));
+      setCancelRemoval({ kind: 'none' });
+      setActionNotice(t('removed_from_calendar'));
+    } catch (err) {
+      setActionError(describeError(err, t('action_failed')));
+    } finally {
+      setIsProcessing(false);
+    }
+  };
+
   if (state === 'loading') {
     return (
       <div className="flex items-center gap-3">
@@ -1010,6 +1063,7 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
         {showDetails && (bannerInfo || actorMessage || actorSummary?.participationComment) && (
           <div className="space-y-0.5 text-xs text-muted-foreground">
             {bannerInfo && <p className="leading-relaxed">{bannerInfo}</p>}
+            {cancellationOutdated && <p className="leading-relaxed">{t('cancel_outdated')}</p>}
             {actorMessage && <p>{actorMessage}</p>}
             {actorSummary?.participationComment && (
               <p className="italic">{t('actor_note', { comment: actorSummary.participationComment })}</p>
@@ -1165,6 +1219,17 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
             </>
           )}
 
+          {canRemoveCancelled && (
+            <button
+              onClick={handleRemoveCancelled}
+              disabled={isProcessing}
+              className="inline-flex items-center gap-1.5 text-sm text-muted-foreground hover:text-destructive px-3 py-1.5 rounded-md border border-border hover:border-destructive/30 hover:bg-destructive/10 transition-colors min-h-[36px] disabled:opacity-50"
+            >
+              <CalendarX className="w-3.5 h-3.5" />
+              {t('remove_from_calendar')}
+            </button>
+          )}
+
           {canApplyProposal && (
             <button
               onClick={handleApplyProposal}

lib/__tests__/calendar-cancellation.test.ts

@@ -0,0 +1,140 @@
+import { describe, expect, it } from 'vitest';
+import { planCancellationRemoval } from '../calendar-cancellation';
+import type { CalendarEvent } from '@/lib/jmap/types';
+
+function stored(overrides: Partial<CalendarEvent>): CalendarEvent {
+  return {
+    id: 'ev-1',
+    uid: 'meeting@example.com',
+    title: 'Weekly sync',
+    start: '2026-11-02T10:00:00',
+    timeZone: 'Europe/Berlin',
+    duration: 'PT1H',
+    sequence: 1,
+    recurrenceId: null,
+    recurrenceRules: null,
+    recurrenceOverrides: null,
+    ...overrides,
+  } as CalendarEvent;
+}
+
+const WEEKLY = [{ '@type': 'RecurrenceRule', frequency: 'weekly' }] as CalendarEvent['recurrenceRules'];
+
+describe('planCancellationRemoval', () => {
+  it('deletes every stored event of a cancelled meeting, and nothing else', () => {
+    const events = [
+      stored({ id: 'ev-1' }),
+      stored({ id: 'ev-2', recurrenceId: '2026-11-09T10:00:00' }),
+      stored({ id: 'other', uid: 'other@example.com' }),
+    ];
+    expect(planCancellationRemoval(events, { uid: 'meeting@example.com', sequence: 1 }))
+      .toEqual({ kind: 'delete', ids: ['ev-1', 'ev-2'] });
+  });
+
+  it('removes nothing when the calendar does not hold the meeting', () => {
+    expect(planCancellationRemoval([stored({ uid: 'other@example.com' })], { uid: 'meeting@example.com' }))
+      .toEqual({ kind: 'none' });
+  });
+
+  it('leaves the meeting when the calendar holds a newer version than the cancellation', () => {
+    expect(planCancellationRemoval([stored({ sequence: 3 })], { uid: 'meeting@example.com', sequence: 2 }))
+      .toEqual({ kind: 'outdated' });
+  });
+
+  it('applies a cancellation with the same sequence, as Stalwart leaves it after marking it cancelled', () => {
+    expect(planCancellationRemoval([stored({ sequence: 2, status: 'cancelled' })], { uid: 'meeting@example.com', sequence: 2 }))
+      .toEqual({ kind: 'delete', ids: ['ev-1'] });
+  });
+
+  it('excludes one cancelled occurrence on the series instead of deleting it', () => {
+    const series = stored({ recurrenceRules: WEEKLY, recurrenceOverrides: null });
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+      sequence: 1,
+    })).toEqual({
+      kind: 'exclude',
+      id: 'ev-1',
+      patch: { recurrenceOverrides: { '2026-11-09T10:00:00': { excluded: true } } },
+    });
+  });
+
+  it('names the occurrence in the series time zone and keeps the other overrides', () => {
+    const series = stored({
+      recurrenceRules: WEEKLY,
+      recurrenceOverrides: { '2026-11-16T10:00:00': { title: 'Moved sync' } },
+    });
+    // 09:00 UTC is 10:00 in Berlin on 9 November.
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T09:00:00',
+      recurrenceIdTimeZone: 'Etc/UTC',
+    })).toEqual({
+      kind: 'exclude',
+      id: 'ev-1',
+      patch: { 'recurrenceOverrides/2026-11-09T10:00:00': { excluded: true } },
+    });
+  });
+
+  it('replaces the override Stalwart wrote for a cancelled occurrence', () => {
+    const series = stored({
+      recurrenceRules: WEEKLY,
+      recurrenceOverrides: { '2026-11-09T10:00:00': { status: 'cancelled', sequence: 1 } },
+    });
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+      sequence: 1,
+    })).toEqual({
+      kind: 'exclude',
+      id: 'ev-1',
+      patch: { 'recurrenceOverrides/2026-11-09T10:00:00': { excluded: true } },
+    });
+  });
+
+  it('leaves an occurrence that was changed after the cancellation was sent', () => {
+    const series = stored({
+      recurrenceRules: WEEKLY,
+      recurrenceOverrides: { '2026-11-09T10:00:00': { title: 'Back on', sequence: 4 } },
+    });
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+      sequence: 3,
+    })).toEqual({ kind: 'outdated' });
+  });
+
+  it('removes nothing for an occurrence already taken out of the series', () => {
+    const series = stored({
+      recurrenceRules: WEEKLY,
+      recurrenceOverrides: { '2026-11-09T10:00:00': { excluded: true } as Partial<CalendarEvent> },
+    });
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+    })).toEqual({ kind: 'none' });
+  });
+
+  it('does not write the whole overrides map when the series was read without it', () => {
+    const series = stored({ recurrenceRules: WEEKLY, recurrenceOverrides: undefined });
+    expect(planCancellationRemoval([series], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+    })).toEqual({ kind: 'none' });
+  });
+
+  it('deletes an occurrence the calendar holds on its own', () => {
+    const occurrence = stored({ id: 'occ', recurrenceId: '2026-11-09T10:00:00', recurrenceIdTimeZone: 'Europe/Berlin' });
+    expect(planCancellationRemoval([occurrence], {
+      uid: 'meeting@example.com',
+      recurrenceId: '2026-11-09T10:00:00',
+      recurrenceIdTimeZone: 'Europe/Berlin',
+      sequence: 1,
+    })).toEqual({ kind: 'delete', ids: ['occ'] });
+  });
+});

lib/calendar-cancellation.ts

@@ -0,0 +1,84 @@
+import type { CalendarEvent } from '@/lib/jmap/types';
+import { buildFallbackExcludePatch } from '@/lib/recurrence-instances';
+import { isValidTimeZone, moveLocalDateTime } from '@/lib/timezone';
+
+/**
+ * `b`'s recurrence id as a local date-time in the zone of `a`'s, each read in
+ * its own zone (`recurrenceIdTimeZone`, else the event's `timeZone`). Without
+ * a usable zone on either side it is taken as it is.
+ */
+function recurrenceIdInZoneOf(a: Partial<CalendarEvent>, b: Partial<CalendarEvent>): string | null {
+  if (!b.recurrenceId) return null;
+  const zoneA = a.recurrenceIdTimeZone ?? a.timeZone ?? null;
+  const zoneB = b.recurrenceIdTimeZone ?? b.timeZone ?? null;
+  const local = b.recurrenceId.slice(0, 19);
+  return zoneA && zoneB && isValidTimeZone(zoneA) && isValidTimeZone(zoneB)
+    ? moveLocalDateTime(local, zoneB, zoneA).slice(0, 19)
+    : local;
+}
+
+/** Whether two events name the same occurrence: their recurrence ids at the same moment, each in its own zone. */
+export function sameRecurrenceId(a: Partial<CalendarEvent>, b: Partial<CalendarEvent>): boolean {
+  if (!a.recurrenceId || !b.recurrenceId) return false;
+  return a.recurrenceId.slice(0, 19) === recurrenceIdInZoneOf(a, b);
+}
+
+/**
+ * What removing a cancelled meeting from the calendar takes:
+ * - `delete`: destroy these stored events (the series, or an occurrence
+ *   stored on its own).
+ * - `exclude`: write `patch` on the series `id`, taking one occurrence out.
+ * - `outdated`: the calendar holds a newer version than the cancellation.
+ * - `none`: nothing in the calendar to remove.
+ */
+export type CancellationRemoval =
+  | { kind: 'delete'; ids: string[] }
+  | { kind: 'exclude'; id: string; patch: Partial<CalendarEvent> }
+  | { kind: 'outdated' }
+  | { kind: 'none' };
+
+/**
+ * How to remove what an iTIP CANCEL (RFC 5546 3.2.5) names from `stored`,
+ * the events stored with its uid. Stalwart applies a cancellation itself but
+ * only marks the event, or the occurrence, STATUS:CANCELLED and keeps it
+ * (#1425). A cancellation without a recurrence id is for the whole meeting;
+ * one with a recurrence id is for that occurrence only. A cancellation with
+ * a lower SEQUENCE than the event it names is older than the event and is
+ * not applied, as Stalwart does not apply it either.
+ */
+export function planCancellationRemoval(
+  stored: CalendarEvent[],
+  cancel: Partial<CalendarEvent>,
+): CancellationRemoval {
+  if (!cancel.uid) return { kind: 'none' };
+  const sameUid = stored.filter((event) => event.uid === cancel.uid);
+  const cancelSequence = cancel.sequence ?? 0;
+  const isNewer = (sequence: number | null | undefined) => (sequence ?? 0) > cancelSequence;
+
+  if (!cancel.recurrenceId) {
+    if (sameUid.length === 0) return { kind: 'none' };
+    if (sameUid.some((event) => isNewer(event.sequence))) return { kind: 'outdated' };
+    return { kind: 'delete', ids: sameUid.map((event) => event.id) };
+  }
+
+  const ownEvent = sameUid.find((event) => sameRecurrenceId(event, cancel));
+  if (ownEvent) {
+    return isNewer(ownEvent.sequence) ? { kind: 'outdated' } : { kind: 'delete', ids: [ownEvent.id] };
+  }
+
+  const series = sameUid.find((event) => !event.recurrenceId && (event.recurrenceRules?.length ?? 0) > 0);
+  // Overrides not read: a whole-map write would drop the ones there are.
+  if (!series || series.recurrenceOverrides === undefined) return { kind: 'none' };
+  const key = recurrenceIdInZoneOf(series, cancel);
+  if (!key) return { kind: 'none' };
+  const override = series.recurrenceOverrides?.[key] as (Partial<CalendarEvent> & { excluded?: boolean }) | undefined;
+  if (override?.excluded) return { kind: 'none' };
+  if (override && isNewer(override.sequence)) return { kind: 'outdated' };
+  const patch = buildFallbackExcludePatch({
+    id: series.id,
+    start: '',
+    recurrenceId: key,
+    recurrenceOverrides: series.recurrenceOverrides,
+  });
+  return patch ? { kind: 'exclude', id: series.id, patch } : { kind: 'none' };
+}

locales/ar/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "موجود بالفعل في تقويمك",
       "request_info": "تمت دعوتك إلى هذا الحدث. أجب لإعلام المنظّم بتوفرك.",
       "cancel_info": "ألغى المنظّم هذا الحدث.",
+      "remove_from_calendar": "إزالة من التقويم",
+      "removed_from_calendar": "أُزيل من تقويمك.",
+      "cancel_outdated": "يحتوي تقويمك على نسخة من هذا الحدث أحدث من هذا الإلغاء.",
       "event_updated": "تحديث رقم {sequence}",
       "event_status_tentative": "مبدئي",
       "event_status_cancelled": "ملغى",

locales/ca/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Ja és al vostre calendari",
       "request_info": "Heu estat convidat a aquest esdeveniment. Responeu per informar l'organitzador de la vostra disponibilitat.",
       "cancel_info": "L'organitzador ha cancel·lat aquest esdeveniment.",
+      "remove_from_calendar": "Treu del calendari",
+      "removed_from_calendar": "S'ha tret del teu calendari.",
+      "cancel_outdated": "El teu calendari té una versió d'aquest esdeveniment més recent que aquesta cancel·lació.",
       "event_updated": "Actualització núm. {sequence}",
       "event_status_tentative": "Provisional",
       "event_status_cancelled": "Cancel·lat",

locales/cs/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Již je ve vašem kalendáři",
       "request_info": "Byli jste pozváni na tuto událost. Odpovězte, abyste informovali organizátora o své dostupnosti.",
       "cancel_info": "Organizátor tuto událost zrušil.",
+      "remove_from_calendar": "Odebrat z kalendáře",
+      "removed_from_calendar": "Odebráno z vašeho kalendáře.",
+      "cancel_outdated": "Váš kalendář obsahuje novější verzi této události než toto zrušení.",
       "event_updated": "Aktualizace #{sequence}",
       "event_status_tentative": "Nezávazně",
       "event_status_cancelled": "Zrušeno",

locales/da/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Allerede i din kalender",
       "request_info": "Du er blevet inviteret til denne begivenhed. Svar for at lade arrangøren kende din tilgængelighed.",
       "cancel_info": "Arrangøren har aflyst denne begivenhed.",
+      "remove_from_calendar": "Fjern fra kalender",
+      "removed_from_calendar": "Fjernet fra din kalender.",
+      "cancel_outdated": "Din kalender har en nyere version af denne begivenhed end denne aflysning.",
       "event_updated": "Opdatering #{sequence}",
       "event_status_tentative": "Foreløbig",
       "event_status_cancelled": "Aflyst",

locales/de/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Bereits in Ihrem Kalender",
       "request_info": "Sie wurden zu diesem Termin eingeladen. Antworten Sie, um dem Organisator Ihre Verfügbarkeit mitzuteilen.",
       "cancel_info": "Der Organisator hat diesen Termin abgesagt.",
+      "remove_from_calendar": "Aus Kalender entfernen",
+      "removed_from_calendar": "Aus Ihrem Kalender entfernt.",
+      "cancel_outdated": "Ihr Kalender enthält eine neuere Version dieses Termins als diese Absage.",
       "event_updated": "Aktualisierung #{sequence}",
       "event_status_tentative": "Vorläufig",
       "event_status_cancelled": "Abgesagt",

locales/en/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Already in your calendar",
       "request_info": "You've been invited to this event. Respond to let the organizer know your availability.",
       "cancel_info": "The organizer has cancelled this event.",
+      "remove_from_calendar": "Remove from calendar",
+      "removed_from_calendar": "Removed from your calendar.",
+      "cancel_outdated": "Your calendar has a newer version of this event than this cancellation.",
       "event_updated": "Update #{sequence}",
       "event_status_tentative": "Tentative",
       "event_status_cancelled": "Cancelled",

locales/es/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Ya está en tu calendario",
       "request_info": "Has sido invitado a este evento. Responde para informar al organizador de tu disponibilidad.",
       "cancel_info": "El organizador ha cancelado este evento.",
+      "remove_from_calendar": "Quitar del calendario",
+      "removed_from_calendar": "Quitado de tu calendario.",
+      "cancel_outdated": "Tu calendario tiene una versión de este evento más reciente que esta cancelación.",
       "event_updated": "Actualización #{sequence}",
       "event_status_tentative": "Provisional",
       "event_status_cancelled": "Cancelado",

locales/et/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Juba sinu kalendris",
       "request_info": "Sind on sellele sündmusele kutsutud. Vasta, et anda korraldajale teada oma saadavusest.",
       "cancel_info": "Korraldaja on selle sündmuse tühistanud.",
+      "remove_from_calendar": "Eemalda kalendrist",
+      "removed_from_calendar": "Eemaldatud sinu kalendrist.",
+      "cancel_outdated": "Sinu kalendris on sellest sündmusest uuem versioon kui see tühistamine.",
       "event_updated": "Uuendus #{sequence}",
       "event_status_tentative": "Esialgne",
       "event_status_cancelled": "Tühistatud",

locales/fa/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "هم‌اکنون در تقویم شماست",
       "request_info": "به این رویداد دعوت شده‌اید. پاسخ دهید.",
       "cancel_info": "برگزارکننده این رویداد را لغو کرده است.",
+      "remove_from_calendar": "حذف از تقویم",
+      "removed_from_calendar": "از تقویم شما حذف شد.",
+      "cancel_outdated": "تقویم شما نسخه‌ای جدیدتر از این رویداد نسبت به این لغو دارد.",
       "event_updated": "به‌روزرسانی #{sequence}",
       "event_status_tentative": "احتمالی",
       "event_status_cancelled": "لغو شده",

locales/fr/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Déjà dans votre calendrier",
       "request_info": "Vous êtes invité à cet événement. Répondez pour informer l'organisateur de votre disponibilité.",
       "cancel_info": "L'organisateur a annulé cet événement.",
+      "remove_from_calendar": "Retirer du calendrier",
+      "removed_from_calendar": "Retiré de votre calendrier.",
+      "cancel_outdated": "Votre calendrier contient une version de cet événement plus récente que cette annulation.",
       "event_updated": "Mise à jour #{sequence}",
       "event_status_tentative": "Provisoire",
       "event_status_cancelled": "Annulé",

locales/he/common.json

@@ -634,6 +634,9 @@
       "already_in_calendar": "כבר בלוח השנה שלך",
       "request_info": "הוזמנת לאירוע זה. השב כדי ליידע את המארגן על זמינותך.",
       "cancel_info": "המארגן ביטל את האירוע הזה.",
+      "remove_from_calendar": "הסרה מהיומן",
+      "removed_from_calendar": "הוסר מהיומן שלך.",
+      "cancel_outdated": "ביומן שלך יש גרסה חדשה יותר של האירוע הזה מאשר הביטול הזה.",
       "event_updated": "עדכון #{sequence}",
       "event_status_tentative": "טנטטיבי",
       "event_status_cancelled": "בוטל",

locales/hu/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Már a naptáradban van",
       "request_info": "Meghívtak erre az eseményre. Válaszolj, hogy a szervező tudja a rendelkezésre állásod.",
       "cancel_info": "A szervező lemondta ezt az eseményt.",
+      "remove_from_calendar": "Eltávolítás a naptárból",
+      "removed_from_calendar": "Eltávolítva a naptárából.",
+      "cancel_outdated": "A naptárában ennek az eseménynek újabb verziója van, mint ez a lemondás.",
       "event_updated": "Frissítés #{sequence}",
       "event_status_tentative": "Előzetes",
       "event_status_cancelled": "Lemondva",

locales/it/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Già nel tuo calendario",
       "request_info": "Sei stato invitato a questo evento. Rispondi per comunicare la tua disponibilità all'organizzatore.",
       "cancel_info": "L'organizzatore ha annullato questo evento.",
+      "remove_from_calendar": "Rimuovi dal calendario",
+      "removed_from_calendar": "Rimosso dal tuo calendario.",
+      "cancel_outdated": "Il tuo calendario contiene una versione di questo evento più recente di questo annullamento.",
       "event_updated": "Aggiornamento #{sequence}",
       "event_status_tentative": "Provvisorio",
       "event_status_cancelled": "Annullato",

locales/ja/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "カレンダーに登録済み",
       "request_info": "このイベントに招待されました。主催者に参加可否をお知らせください。",
       "cancel_info": "主催者がこのイベントをキャンセルしました。",
+      "remove_from_calendar": "カレンダーから削除",
+      "removed_from_calendar": "カレンダーから削除しました。",
+      "cancel_outdated": "カレンダーにはこのキャンセルより新しいバージョンの予定があります。",
       "event_updated": "更新 #{sequence}",
       "event_status_tentative": "仮",
       "event_status_cancelled": "キャンセル済み",

locales/ko/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "이미 내 캘린더에 있어요",
       "request_info": "이 일정에 초대받았어요. 참석 가능 여부를 주최자에게 알려주세요.",
       "cancel_info": "주최자가 이 일정을 취소했어요.",
+      "remove_from_calendar": "캘린더에서 제거",
+      "removed_from_calendar": "캘린더에서 제거했습니다.",
+      "cancel_outdated": "캘린더에 이 취소보다 최신 버전의 일정이 있습니다.",
       "event_updated": "업데이트 #{sequence}",
       "event_status_tentative": "미정",
       "event_status_cancelled": "취소됨",

locales/lv/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Jau ir jūsu kalendārā",
       "request_info": "Jūs esat uzaicināts uz šo pasākumu. Lūdzu, atbildiet.",
       "cancel_info": "Organizators atcēla šo pasākumu.",
+      "remove_from_calendar": "Noņemt no kalendāra",
+      "removed_from_calendar": "Noņemts no jūsu kalendāra.",
+      "cancel_outdated": "Jūsu kalendārā ir jaunāka šī notikuma versija nekā šis atcelšanas paziņojums.",
       "event_updated": "Atjauninājums Nr. {sequence}",
       "event_status_tentative": "Pagaidām",
       "event_status_cancelled": "Atcelts",

locales/mn/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Таны хуанлид аль хэдийн орсон",
       "request_info": "Таныг энэ арга хэмжээнд урьсан. Зохион байгуулагчид боломжоо мэдэгдэхийн тулд хариу бичнэ үү.",
       "cancel_info": "Зохион байгуулагч энэ арга хэмжээг цуцалсан.",
+      "remove_from_calendar": "Хуанлиас хасах",
+      "removed_from_calendar": "Таны хуанлиас хасагдлаа.",
+      "cancel_outdated": "Таны хуанлид энэ үйл явдлын энэ цуцлалтаас шинэ хувилбар байна.",
       "event_updated": "Шинэчлэх #{sequence}",
       "event_status_tentative": "Урьдчилсан",
       "event_status_cancelled": "Цуцлагдсан",

locales/nb/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Allerede i kalenderen din",
       "request_info": "Du er invitert til denne hendelsen. Svar for å gi arrangøren beskjed om du kan delta.",
       "cancel_info": "Arrangøren har avlyst denne hendelsen.",
+      "remove_from_calendar": "Fjern fra kalenderen",
+      "removed_from_calendar": "Fjernet fra kalenderen din.",
+      "cancel_outdated": "Kalenderen din har en nyere versjon av denne hendelsen enn denne avlysningen.",
       "event_updated": "Oppdatering #{sequence}",
       "event_status_tentative": "Foreløpig",
       "event_status_cancelled": "Avlyst",

locales/nl/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Staat al in je agenda",
       "request_info": "Je bent uitgenodigd voor dit evenement. Reageer om de organisator te laten weten of je kunt deelnemen.",
       "cancel_info": "De organisator heeft dit evenement geannuleerd.",
+      "remove_from_calendar": "Uit agenda verwijderen",
+      "removed_from_calendar": "Uit je agenda verwijderd.",
+      "cancel_outdated": "Je agenda bevat een nieuwere versie van dit evenement dan deze annulering.",
       "event_updated": "Update #{sequence}",
       "event_status_tentative": "Voorlopig",
       "event_status_cancelled": "Geannuleerd",

locales/pl/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Już w Twoim kalendarzu",
       "request_info": "Zostałeś zaproszony na to wydarzenie. Odpowiedz, aby poinformować organizatora o swojej dostępności.",
       "cancel_info": "Organizator anulował to wydarzenie.",
+      "remove_from_calendar": "Usuń z kalendarza",
+      "removed_from_calendar": "Usunięto z Twojego kalendarza.",
+      "cancel_outdated": "Twój kalendarz zawiera nowszą wersję tego wydarzenia niż to odwołanie.",
       "event_updated": "Aktualizacja #{sequence}",
       "event_status_tentative": "Wstępne",
       "event_status_cancelled": "Anulowane",

locales/pt/common.json

@@ -684,6 +684,9 @@
       "already_in_calendar": "Já está no seu calendário",
       "request_info": "Você foi convidado para este evento. Responda para informar o organizador sobre sua disponibilidade.",
       "cancel_info": "O organizador cancelou este evento.",
+      "remove_from_calendar": "Remover do calendário",
+      "removed_from_calendar": "Removido do seu calendário.",
+      "cancel_outdated": "O seu calendário tem uma versão deste evento mais recente do que este cancelamento.",
       "event_updated": "Atualização #{sequence}",
       "event_status_tentative": "Provisório",
       "event_status_cancelled": "Cancelado",

locales/ro/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Deja în calendarul dvs.",
       "request_info": "Ați fost invitat la acest eveniment. Răspundeți pentru a-i comunica organizatorului disponibilitatea dumneavoastră.",
       "cancel_info": "Organizatorul a anulat acest eveniment.",
+      "remove_from_calendar": "Elimină din calendar",
+      "removed_from_calendar": "Eliminat din calendarul tău.",
+      "cancel_outdated": "Calendarul tău are o versiune a acestui eveniment mai nouă decât această anulare.",
       "event_updated": "Actualizați # {sequence}",
       "event_status_tentative": "Provizoriu",
       "event_status_cancelled": "Anulat",

locales/ru/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Уже в вашем календаре",
       "request_info": "Вас пригласили на это событие. Ответьте, чтобы организатор знал о вашей доступности.",
       "cancel_info": "Организатор отменил это событие.",
+      "remove_from_calendar": "Удалить из календаря",
+      "removed_from_calendar": "Удалено из вашего календаря.",
+      "cancel_outdated": "В вашем календаре более новая версия этого события, чем эта отмена.",
       "event_updated": "Обновление №{sequence}",
       "event_status_tentative": "Под вопросом",
       "event_status_cancelled": "Отменено",

locales/sk/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "Už je vo vašom kalendári",
       "request_info": "Boli ste pozvaní na túto udalosť. Odpovedzte, aby organizátor vedel o vašej dostupnosti.",
       "cancel_info": "Organizátor zrušil túto udalosť.",
+      "remove_from_calendar": "Odstrániť z kalendára",
+      "removed_from_calendar": "Odstránené z vášho kalendára.",
+      "cancel_outdated": "Váš kalendár obsahuje novšiu verziu tejto udalosti než toto zrušenie.",
       "event_updated": "Aktualizácia #{sequence}",
       "event_status_tentative": "Nezaväzne",
       "event_status_cancelled": "Zrušené",

locales/th/common.json

@@ -1646,6 +1646,9 @@
       "already_in_calendar": "มีกิจกรรมนี้ในปฏิทินของคุณแล้ว",
       "request_info": "คำขอเข้าร่วมกิจกรรม",
       "cancel_info": "กิจกรรมนี้ถูกยกเลิกแล้ว",
+      "remove_from_calendar": "นำออกจากปฏิทิน",
+      "removed_from_calendar": "นำออกจากปฏิทินของคุณแล้ว",
+      "cancel_outdated": "ปฏิทินของคุณมีเวอร์ชันของกิจกรรมนี้ที่ใหม่กว่าการยกเลิกนี้",
       "event_updated": "การอัปเดตครั้งที่ #{sequence}",
       "event_status_tentative": "สถานะ: รอการยืนยัน",
       "event_status_cancelled": "สถานะ: ยกเลิกแล้ว",

locales/tr/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Zaten takviminizde",
       "request_info": "Bu etkinliğe davet edildiniz. Müsaitliğinizi bildirmek için yanıt verin.",
       "cancel_info": "Organizatör bu etkinliği iptal etti.",
+      "remove_from_calendar": "Takvimden kaldır",
+      "removed_from_calendar": "Takviminizden kaldırıldı.",
+      "cancel_outdated": "Takviminizde bu etkinliğin bu iptalden daha yeni bir sürümü var.",
       "event_updated": "Güncelleme #{sequence}",
       "event_status_tentative": "Belirsiz",
       "event_status_cancelled": "İptal edildi",

locales/uk/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "Уже у вашому календарі",
       "request_info": "Вас запросили на цю подію. Дайте відповідь, щоб повідомити організатора про вашу доступність.",
       "cancel_info": "Організатор скасував цю подію.",
+      "remove_from_calendar": "Видалити з календаря",
+      "removed_from_calendar": "Видалено з вашого календаря.",
+      "cancel_outdated": "У вашому календарі новіша версія цієї події, ніж це скасування.",
       "event_updated": "Оновлення №{sequence}",
       "event_status_tentative": "Орієнтовний",
       "event_status_cancelled": "Скасовано",

locales/zh-TW/common.json

@@ -711,6 +711,9 @@
       "already_in_calendar": "已在您的行事曆中",
       "request_info": "您已受邀參加此活動。請回覆，讓主辦人知道您是否能參加。",
       "cancel_info": "主辦人已取消此活動。",
+      "remove_from_calendar": "從行事曆移除",
+      "removed_from_calendar": "已從你的行事曆移除。",
+      "cancel_outdated": "你的行事曆中此活動的版本比這份取消通知更新。",
       "event_updated": "更新 #{sequence}",
       "event_status_tentative": "暫定",
       "event_status_cancelled": "已取消",

locales/zh/common.json

@@ -686,6 +686,9 @@
       "already_in_calendar": "已在你的日历中",
       "request_info": "您已被邀请参加此活动。回复以让组织者了解您是否参加。",
       "cancel_info": "组织者已取消此活动。",
+      "remove_from_calendar": "从日历中移除",
+      "removed_from_calendar": "已从你的日历中移除。",
+      "cancel_outdated": "你的日历中此活动的版本比这份取消通知更新。",
       "event_updated": "更新 #{sequence}",
       "event_status_tentative": "暂定",
       "event_status_cancelled": "已取消",