Clean up event alerts and ensure reliable dedupe

packages/backend/src/jobs/event-alert.job.spec.ts

@@ -59,6 +59,7 @@ describe('EventAlertJob', () => {
     await job.run(new Date('2026-04-21T12:00:00.000Z'));
 
     expect(sendMessageMock).toHaveBeenCalledOnce();
+    expect(sendMessageMock).toHaveBeenCalledWith('#events', expect.stringContaining(':sunny: Happening today:\n'));
     expect(sendMessageMock).toHaveBeenCalledWith('#events', expect.stringContaining('Planning 🚀 @ HQ'));
     // Times should use Slack's <!date^…> format so each user sees them in their own Slack timezone.
     // Unix seconds: start=1776787200 (2026-04-21T16:00Z), end=1776790800 (2026-04-21T17:00Z)
@@ -77,6 +78,47 @@ describe('EventAlertJob', () => {
     expect(setValueWithExpireMock).toHaveBeenCalledOnce();
   });
 
+  it('splits today events from later upcoming events in the same 24 hour window', async () => {
+    listUpcomingOccurrencesMock.mockResolvedValue([
+      {
+        teamId: 'T123',
+        occurrences: [
+          {
+            occurrenceId: '1:2026-04-21T16:00:00.000Z',
+            seriesId: '1',
+            title: 'Today Planning',
+            location: null,
+            startsAt: '2026-04-21T16:00:00.000Z',
+            endsAt: '2026-04-21T17:00:00.000Z',
+            isAllDay: false,
+            isRecurring: false,
+          },
+          {
+            occurrenceId: '2:2026-04-22T06:00:00.000Z',
+            seriesId: '2',
+            title: 'Tomorrow Standup',
+            location: 'Zoom',
+            startsAt: '2026-04-22T06:00:00.000Z',
+            endsAt: '2026-04-22T06:30:00.000Z',
+            isAllDay: false,
+            isRecurring: false,
+          },
+        ],
+      },
+    ]);
+
+    const job = new EventAlertJob();
+    await job.run(new Date('2026-04-21T12:00:00.000Z'));
+
+    expect(sendMessageMock).toHaveBeenCalledOnce();
+    const [channel, message] = sendMessageMock.mock.calls[0];
+    expect(channel).toBe('#events');
+    expect(message).toContain(':hourglass_flowing_sand: Upcoming in the next 24 hours:\n- ');
+    expect(message).toContain('Tomorrow Standup @ Zoom');
+    expect(message).toContain(':sunny: Happening today:\n- ');
+    expect(message).toContain('Today Planning');
+  });
+
   it('formats all-day multi-day events as date ranges', async () => {
     listUpcomingOccurrencesMock.mockResolvedValue([
       {

packages/backend/src/jobs/event-alert.job.ts

@@ -3,6 +3,7 @@ import { logger } from '../shared/logger/logger';
 import { logError } from '../shared/logger/error-logging';
 import { RedisPersistenceService } from '../shared/services/redis.persistence.service';
 import { WebService } from '../shared/services/web/web.service';
+import type { CalendarEventOccurrence } from '../calendar/calendar.model';
 
 const ALERT_CHANNEL = process.env.EVENTS_ALERT_CHANNEL ?? '#events';
 const ALERT_LOOKAHEAD_MS = 24 * 60 * 60 * 1000;
@@ -28,6 +29,23 @@ const subtractOneDayUtc = (value: Date): Date => {
   return next;
 };
 
+const startOfUtcDay = (value: Date): Date =>
+  new Date(Date.UTC(value.getUTCFullYear(), value.getUTCMonth(), value.getUTCDate()));
+
+const addOneDayUtc = (value: Date): Date => {
+  const next = new Date(value);
+  next.setUTCDate(next.getUTCDate() + 1);
+  return next;
+};
+
+const occursTodayUtc = (occurrence: CalendarEventOccurrence, now: Date): boolean => {
+  const dayStart = startOfUtcDay(now);
+  const nextDayStart = addOneDayUtc(dayStart);
+  const start = new Date(occurrence.startsAt);
+  const end = new Date(occurrence.endsAt);
+  return end > dayStart && start < nextDayStart;
+};
+
 const formatOccurrenceWindow = (startsAt: string, endsAt: string, isAllDay: boolean): string => {
   if (isAllDay) {
     // All-day events are stored as midnight UTC boundaries; use plain UTC date labels.
@@ -58,6 +76,28 @@ const formatOccurrenceWindow = (startsAt: string, endsAt: string, isAllDay: bool
   return `${slackTimestamp(start, '{date_short} at {time}', startFallback)} - ${slackTimestamp(end, '{date_short} at {time}', endFallback)}`;
 };
 
+const formatOccurrenceLine = (occurrence: CalendarEventOccurrence): string => {
+  const locationSuffix = occurrence.location ? ` @ ${occurrence.location}` : '';
+  const occurrenceWindow = formatOccurrenceWindow(occurrence.startsAt, occurrence.endsAt, occurrence.isAllDay);
+  return `- ${occurrenceWindow} - ${occurrence.title}${locationSuffix}`;
+};
+
+const formatAlertSection = (title: string, occurrences: CalendarEventOccurrence[]): string | null => {
+  if (!occurrences.length) {
+    return null;
+  }
+
+  return `${title}:\n${occurrences.map(formatOccurrenceLine).join('\n')}`;
+};
+
+const formatAlertMessage = (emoji: string, title: string, occurrences: CalendarEventOccurrence[]): string | null => {
+  const section = formatAlertSection(title, occurrences);
+  if (!section) {
+    return null;
+  }
+  return `${emoji} ${section}`;
+};
+
 export class EventAlertJob {
   private calendarPersistenceService = new CalendarPersistenceService();
   private webService = new WebService();
@@ -104,24 +144,31 @@ export class EventAlertJob {
             return;
           }
 
-          const lines = unsentOccurrences
-            .slice(0, 20)
-            .map((occurrence) => {
-              const locationSuffix = occurrence.location ? ` @ ${occurrence.location}` : '';
-              const occurrenceWindow = formatOccurrenceWindow(
-                occurrence.startsAt,
-                occurrence.endsAt,
-                occurrence.isAllDay,
-              );
-              return `- ${occurrenceWindow} - ${occurrence.title}${locationSuffix}`;
-            })
-            .join('\n');
-
-          const overflowCount = unsentOccurrences.length - Math.min(20, unsentOccurrences.length);
+          const displayedOccurrences = unsentOccurrences.slice(0, 20);
+          const todayOccurrences: CalendarEventOccurrence[] = [];
+          const upcomingOccurrencesLater: CalendarEventOccurrence[] = [];
+          for (const occurrence of displayedOccurrences) {
+            if (occursTodayUtc(occurrence, now)) {
+              todayOccurrences.push(occurrence);
+            } else {
+              upcomingOccurrencesLater.push(occurrence);
+            }
+          }
+
+          const overflowCount = unsentOccurrences.length - displayedOccurrences.length;
           const overflowLine = overflowCount > 0 ? `\n...and ${overflowCount} more event(s).` : '';
-          const text = `:calendar: Upcoming events in the next 24 hours:\n${lines}${overflowLine}`;
+          const upcomingMessage = formatAlertMessage(
+            ':hourglass_flowing_sand:',
+            'Upcoming in the next 24 hours',
+            upcomingOccurrencesLater,
+          );
+          const todayMessage = formatAlertMessage(':sunny:', 'Happening today', todayOccurrences);
 
-          await this.webService.sendMessage(ALERT_CHANNEL, text);
+          const messages = [upcomingMessage, todayMessage].filter((message): message is string => Boolean(message));
+          if (!messages.length) {
+            return;
+          }
+          await this.webService.sendMessage(ALERT_CHANNEL, `${messages.join('\n\n')}${overflowLine}`);
 
           await Promise.all(
             unsentOccurrences.map((occurrence) =>