fix: close an untouched all-day event without asking to discard changes

src/components/calendar/EventModal.tsx

@@ -82,7 +82,7 @@ import { SafeAreaModal } from '../SafeAreaModal';
 import { useKeyboardObstruction } from '../../lib/use-keyboard-obstruction';
 import { editorKeyboardInset } from '../../lib/calendar-editor-keyboard';
 import ToggleSwitch from '../ToggleSwitch';
-import { askBeforeDiscard, editorFormChanged, editorFormSnapshot } from '../../lib/calendar-editor-discard';
+import { askBeforeDiscard, editorFormChanged, editorFormSnapshot, editorTimesSnapshot } from '../../lib/calendar-editor-discard';
 import { saveOfferingWithoutInvitations } from '../../lib/calendar-scheduling-denied';
 
 type RecurrenceOption = 'none' | 'daily' | 'weekly' | 'monthly' | 'yearly' | 'custom';
@@ -269,7 +269,7 @@ export function EventModal({
   // What the form holds against what it opened with: Close and Back ask
   // before they drop changes (webmail 13f9f27c4).
   const formSnapshot = React.useMemo(() => editorFormSnapshot({
-    title, description, allDay, start, end, calendarId, attendees, recurrence, customRule,
+    title, description, times: editorTimesSnapshot({ allDay, start, end }), calendarId, attendees, recurrence, customRule,
     reminders, useDefaults, preserved, sendInvitations, location, videoUrl,
   }), [title, description, allDay, start, end, calendarId, attendees, recurrence, customRule,
     reminders, useDefaults, preserved, sendInvitations, location, videoUrl]);

src/lib/__tests__/calendar-editor-discard.test.ts

@@ -3,8 +3,12 @@ import { describe, it, expect, vi, beforeEach } from 'vitest';
 const alert = vi.fn();
 vi.mock('react-native', () => ({ Alert: { alert: (...args: unknown[]) => alert(...args) } }));
 
-import { askBeforeDiscard, editorFormChanged, editorFormSnapshot } from '../calendar-editor-discard';
+import { askBeforeDiscard, editorFormChanged, editorFormSnapshot, editorTimesSnapshot } from '../calendar-editor-discard';
 import { emptyTaskEditor, taskEditorChanged, taskEditorFromTask } from '../task-editor';
+import { editorTimesFromEvent } from '../event-editor-times';
+import type { CalendarEvent } from '../../api/types';
+import fs from 'node:fs';
+import path from 'node:path';
 
 const t = (_key: string, fallback?: string) => fallback ?? '';
 
@@ -13,6 +17,48 @@ const buttons = (): Button[] => alert.mock.calls.at(-1)![2] as Button[];
 
 beforeEach(() => alert.mockReset());
 
+describe('the event editor times in the dirty check', () => {
+  // What the editor does with an all-day event it opens: seed the times,
+  // then its all-day effect sets start and end to midnight.
+  const opened = (event: Partial<CalendarEvent>) => {
+    const seeded = editorTimesFromEvent(event as CalendarEvent);
+    const s = new Date(seeded.start); s.setHours(0, 0, 0, 0);
+    const e = new Date(seeded.end); e.setHours(0, 0, 0, 0);
+    if (e < s) e.setTime(s.getTime());
+    return { seeded, normalized: { allDay: seeded.allDay, start: s, end: e } };
+  };
+  const snap = (times: { allDay: boolean; start: Date; end: Date }) =>
+    editorFormSnapshot({ title: 'Company holiday', times: editorTimesSnapshot(times) });
+
+  it('finds no change in an all-day event opened and left alone', () => {
+    // "Company holiday" as Stalwart 0.16 returns it: a day, P1D.
+    const { seeded, normalized } = opened({
+      '@type': 'Event', showWithoutTime: true, start: '2026-10-03T00:00:00', duration: 'P1D',
+    } as Partial<CalendarEvent>);
+    expect(seeded.end.getHours()).toBe(23); // the inclusive last day, 23:59:59.999
+    expect(editorFormChanged(snap(seeded), snap(normalized))).toBe(false);
+    // Two days, and one with a time zone attached.
+    const two = opened({ showWithoutTime: true, start: '2026-10-03T00:00:00', duration: 'P2D' });
+    expect(editorFormChanged(snap(two.seeded), snap(two.normalized))).toBe(false);
+    const zoned = opened({ showWithoutTime: true, start: '2026-10-03T00:00:00', duration: 'P1D', timeZone: 'Europe/Berlin' });
+    expect(editorFormChanged(snap(zoned.seeded), snap(zoned.normalized))).toBe(false);
+  });
+
+  it('still sees another day, and a moved timed event', () => {
+    const { normalized } = opened({ showWithoutTime: true, start: '2026-10-03T00:00:00', duration: 'P1D' });
+    const nextDay = { ...normalized, end: new Date(normalized.end.getTime() + 86_400_000) };
+    expect(editorFormChanged(snap(normalized), snap(nextDay))).toBe(true);
+    const timed = { allDay: false, start: new Date(2026, 9, 3, 9), end: new Date(2026, 9, 3, 10) };
+    expect(editorFormChanged(snap(timed), snap({ ...timed, end: new Date(2026, 9, 3, 10, 30) }))).toBe(true);
+    expect(editorFormChanged(snap(timed), snap({ ...timed, allDay: true }))).toBe(true);
+  });
+
+  it('is what the event editor compares', () => {
+    const src = fs.readFileSync(path.resolve(__dirname, '../../components/calendar/EventModal.tsx'), 'utf8');
+    expect(src).toMatch(/times: editorTimesSnapshot\(\{ allDay, start, end \}\)/);
+  });
+});
+
 describe('askBeforeDiscard', () => {
   it('closes at once when nothing was changed', () => {
     const close = vi.fn();

src/lib/calendar-editor-discard.ts

@@ -11,6 +11,23 @@ export function editorFormSnapshot(fields: Record<string, unknown>): string {
   return JSON.stringify(fields);
 }
 
+/**
+ * The editor's times as the dirty check compares them. An all-day event
+ * compares by its first and last day: the editor seeds its last day as
+ * 23:59:59.999 (the exclusive end minus 1 ms) and then sets both to
+ * midnight, so comparing instants asked "Discard changes?" for an all-day
+ * event opened and closed untouched. A timed one compares by the instant.
+ */
+export function editorTimesSnapshot(times: { allDay: boolean; start: Date; end: Date }): Record<string, unknown> {
+  if (!times.allDay) return { allDay: false, start: times.start, end: times.end };
+  return { allDay: true, start: dayKey(times.start), end: dayKey(times.end) };
+}
+
+function dayKey(date: Date): string {
+  const pad = (n: number) => String(n).padStart(2, '0');
+  return `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}`;
+}
+
 /** Whether the form holds changes against `baseline`, the form it opened with (null: not seeded yet). */
 export function editorFormChanged(baseline: string | null, current: string): boolean {
   return baseline !== null && baseline !== current;