fix: keep event cards whose last day ends after a daylight saving change

lib/structured-mail/__tests__/validate-resolve.test.ts

@@ -122,6 +122,20 @@ describe('resolveCards', () => {
     expect((card as { checkin: { time?: string } }).checkin.time).toBeUndefined();
   });
 
+  it('ends a date-only event end at midnight local time even across a DST change', async () => {
+    const event = (country?: string) => ({
+      '@context': ctx, '@type': 'EventReservation', reservationNumber: 'EV1',
+      reservationFor: {
+        '@type': 'Event', name: 'Herbstmesse', startDate: '2026-10-23T18:00:00+02:00', endDate: '2026-10-26',
+        location: { '@type': 'Place', name: 'Messe', ...(country ? { address: { addressCountry: country } } : {}) },
+      },
+    });
+    const [withVenue] = await resolved(event('DE'));
+    expect(withVenue).toMatchObject({ end: { date: '2026-10-26', time: '23:59:59', zone: 'Europe/Berlin', utc: '2026-10-26T22:59:59Z' } });
+    const [noVenueCountry] = await resolved(event());
+    expect(noVenueCountry).toMatchObject({ end: { date: '2026-10-26', time: '23:59:59', zone: 'Etc/GMT-2', utc: '2026-10-26T21:59:59Z' } });
+  });
+
   it('reads bus times in the single zone of the stop\'s country', async () => {
     const [card] = (await resolved({
       '@context': ctx, '@type': 'BusReservation', reservationNumber: 'B',

lib/structured-mail/normalize.ts

@@ -231,12 +231,6 @@ function base(kind: BookingKind, res: Obj, source: CardSource) {
 
 const MISSING: Moment = { date: '' };
 
-function offsetSuffix(minutes: number): string {
-  const sign = minutes < 0 ? '-' : '+';
-  const abs = Math.abs(minutes);
-  return `${sign}${String(Math.floor(abs / 60)).padStart(2, '0')}:${String(abs % 60).padStart(2, '0')}`;
-}
-
 function reservation(kind: BookingKind, res: Obj, source: CardSource): StructuredCard | undefined {
   if (kind === 'flight' || kind === 'train' || kind === 'bus') return transport(kind, res, source);
   const target = obj(res.reservationFor) ?? {};
@@ -275,8 +269,9 @@ function reservation(kind: BookingKind, res: Obj, source: CardSource): Structure
       let end = moment(target.endDate);
       // An end date without a time means the end of that day, when the
       // event starts at a time; with a date-only start it's an all-day span.
-      if (end && !end.time && start?.time) end = { ...end, time: '23:59:59', ...(start.offsetMinutes !== undefined ? { offsetMinutes: start.offsetMinutes } : {}) };
-      if (end?.offsetMinutes !== undefined && end.time && !end.utc) end = moment(`${end.date}T${end.time}${offsetSuffix(end.offsetMinutes)}`);
+      // The end carries no offset: the day may end on the other side of a
+      // DST change, so resolve.ts reads it in the zone the start resolves to.
+      if (end && !end.time && start?.time) end = { ...end, time: '23:59:59' };
       return {
         ...base(kind, res, source),
         kind,

lib/structured-mail/resolve.ts

@@ -116,8 +116,14 @@ function resolveCard(card: StructuredCard, zoneOf: ZoneOf | undefined): Structur
     case 'event': {
       const named = (m: Moment) => namedZone(card.venue, card.kind, zoneOf, m.offsetMinutes === undefined);
       const start = resolveMoment(card.start, named(card.start));
-      const end = card.end ? resolveMoment(card.end, named(card.end)) : undefined;
-      if (start === 'drop' || end === 'drop') return null;
+      if (start === 'drop') return null;
+      // An end without its own offset (a date-only end turned into the end of
+      // that day) belongs to the start's zone when the venue names none.
+      const endNamed = card.end && card.end.offsetMinutes === undefined && !named(card.end) && start.zone
+        ? { zone: start.zone, source: 'country' as const }
+        : card.end ? named(card.end) : undefined;
+      const end = card.end ? resolveMoment(card.end, endNamed) : undefined;
+      if (end === 'drop') return null;
       if (end && !notBefore(end, start)) return null;
       return { ...card, start, ...(end ? { end } : {}) };
     }