fix: Minimum fix for N Calendar Invites

packages/app-store/_utils/calendars/processExternalId.ts

@@ -0,0 +1,18 @@
+import type { DestinationCalendar } from "@prisma/client";
+
+import { metadata as OutlookMetadata } from "../../office365calendar";
+
+/**
+ * When inviting attendees to a calendar event, sometimes the external ID is only used for internal purposes
+ * Need to process the correct external ID for the calendar service
+ */
+const processExternalId = (destinationCalendar: DestinationCalendar) => {
+  if (destinationCalendar.integration === OutlookMetadata.type) {
+    // Primary email should always be present for Outlook
+    return destinationCalendar.primaryEmail || destinationCalendar.externalId;
+  }
+
+  return destinationCalendar.externalId;
+};
+
+export default processExternalId;

packages/core/EventManager.ts

@@ -535,6 +535,7 @@ export default class EventManager {
     };
 
     if (event.destinationCalendar && event.destinationCalendar.length > 0) {
+      let eventCreated = false;
       // Since GCal pushes events to multiple calendars we only want to create one event per booking
       let gCalAdded = false;
       const destinationCalendars: DestinationCalendar[] = event.destinationCalendar.reduce(
@@ -554,6 +555,7 @@ export default class EventManager {
         [] as DestinationCalendar[]
       );
       for (const destination of destinationCalendars) {
+        if (eventCreated) break;
         log.silly("Creating Calendar event", JSON.stringify({ destination }));
         if (destination.credentialId) {
           let credential = this.calendarCredentials.find((c) => c.id === destination.credentialId);
@@ -582,6 +584,7 @@ export default class EventManager {
             const createdEvent = await createEvent(credential, event, destination.externalId);
             if (createdEvent) {
               createdEvents.push(createdEvent);
+              eventCreated = true;
             }
           }
         } else {
@@ -607,6 +610,7 @@ export default class EventManager {
               })
             );
             createdEvents.push(await createEvent(firstCalendarCredential, event));
+            eventCreated = true;
           }
         }
       }

packages/features/bookings/lib/handleNewBooking.ts

@@ -11,6 +11,7 @@ import type { Logger } from "tslog";
 import { v5 as uuidv5 } from "uuid";
 import z from "zod";
 
+import processExternalId from "@calcom/app-store/_utils/calendars/processExternalId";
 import { metadata as GoogleMeetMetadata } from "@calcom/app-store/googlevideo/_metadata";
 import type { LocationObject } from "@calcom/app-store/locations";
 import {
@@ -1405,9 +1406,13 @@ async function handler(
 
   // Organizer or user owner of this event type it's not listed as a team member.
   const teamMemberPromises = users.slice(1).map(async (user) => {
+    // TODO: Add back once EventManager tests are ready https://github.com/calcom/cal.com/pull/14610#discussion_r1567817120
     // push to teamDestinationCalendars if it's a team event but collective only
     if (isTeamEventType && eventType.schedulingType === "COLLECTIVE" && user.destinationCalendar) {
-      teamDestinationCalendars.push(user.destinationCalendar);
+      teamDestinationCalendars.push({
+        ...user.destinationCalendar,
+        externalId: processExternalId(user.destinationCalendar),
+      });
     }
 
     return {