nextcloud · SebastianKrupinski · Sep 21, 2026
@@ -63,7 +63,6 @@
     'OCA\\DAV\\CalDAV\\CalendarRoot' => $baseDir . '/../lib/CalDAV/CalendarRoot.php',
     'OCA\\DAV\\CalDAV\\DefaultCalendarValidator' => $baseDir . '/../lib/CalDAV/DefaultCalendarValidator.php',
     'OCA\\DAV\\CalDAV\\EmbeddedCalDavServer' => $baseDir . '/../lib/CalDAV/EmbeddedCalDavServer.php',
-    'OCA\\DAV\\CalDAV\\EventComparisonService' => $baseDir . '/../lib/CalDAV/EventComparisonService.php',
     'OCA\\DAV\\CalDAV\\EventReader' => $baseDir . '/../lib/CalDAV/EventReader.php',
     'OCA\\DAV\\CalDAV\\EventReaderRDate' => $baseDir . '/../lib/CalDAV/EventReaderRDate.php',
     'OCA\\DAV\\CalDAV\\EventReaderRRule' => $baseDir . '/../lib/CalDAV/EventReaderRRule.php',

@@ -78,7 +78,6 @@ class ComposerStaticInitDAV
         'OCA\\DAV\\CalDAV\\CalendarRoot' => __DIR__ . '/..' . '/../lib/CalDAV/CalendarRoot.php',
         'OCA\\DAV\\CalDAV\\DefaultCalendarValidator' => __DIR__ . '/..' . '/../lib/CalDAV/DefaultCalendarValidator.php',
         'OCA\\DAV\\CalDAV\\EmbeddedCalDavServer' => __DIR__ . '/..' . '/../lib/CalDAV/EmbeddedCalDavServer.php',
-        'OCA\\DAV\\CalDAV\\EventComparisonService' => __DIR__ . '/..' . '/../lib/CalDAV/EventComparisonService.php',
         'OCA\\DAV\\CalDAV\\EventReader' => __DIR__ . '/..' . '/../lib/CalDAV/EventReader.php',
         'OCA\\DAV\\CalDAV\\EventReaderRDate' => __DIR__ . '/..' . '/../lib/CalDAV/EventReaderRDate.php',
         'OCA\\DAV\\CalDAV\\EventReaderRRule' => __DIR__ . '/..' . '/../lib/CalDAV/EventReaderRRule.php',

@@ -10,7 +10,6 @@
 namespace OCA\DAV\CalDAV\Schedule;
 
 use OCA\DAV\CalDAV\CalendarObject;
-use OCA\DAV\CalDAV\EventComparisonService;
 use OCP\Accounts\IAccountManager;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Defaults;
@@ -65,7 +64,6 @@ public function __construct(
 		private Defaults $defaults,
 		private IUserSession $userSession,
 		private IMipService $imipService,
-		private EventComparisonService $eventComparisonService,
 		private IMailManager $mailManager,
 		private IEmailValidator $emailValidator,
 		private IAccountManager $accountManager,
@@ -149,26 +147,45 @@ public function schedule(Message $iTipMessage) {
 		$newEvents = $iTipMessage->message;
 		$oldEvents = $this->getVCalendar();
 
-		$modified = $this->eventComparisonService->findModified($newEvents, $oldEvents);
-		/** @var VEvent $vEvent */
-		$vEvent = array_pop($modified['new']);
-		/** @var VEvent $oldVevent */
-		$oldVevent = !empty($modified['old']) && is_array($modified['old']) ? array_pop($modified['old']) : null;
-		$isModified = isset($oldVevent);
+		$modifiedInstances = $this->imipService->findModifiedInstances($newEvents, $oldEvents);
 
 		// No changed events after all - this shouldn't happen if there is significant change yet here we are
 		// The scheduling status is debatable
-		if (empty($vEvent)) {
+		if (empty($modifiedInstances)) {
 			$this->logger->warning('iTip message said the change was significant but comparison did not detect any updated VEvents');
 			$iTipMessage->scheduleStatus = '1.0;We got the message, but it\'s not significant enough to warrant an email';
 			return;
 		}
 
-		// we (should) have one event component left
-		// as the ITip\Broker creates one iTip message per change
-		// and triggers the "schedule" event once per message
-		// we also might not have an old event as this could be a new
-		// invitation, or a new recurrence exception
+		// we (should) have one changed instance per message, as the ITip\Broker
+		// creates one iTip message per attendee and triggers the "schedule"
+		// event once per message; a message can still bundle several changed
+		// instances (e.g. master + overrides edited together), in which case
+		// only the primary instance is reflected in the email for now
+		$primaryInstance = null;
+		foreach ($modifiedInstances as $instance) {
+			if (!isset($instance['new']->{'RECURRENCE-ID'})) {
+				$primaryInstance = $instance;
+				break;
+			}
+		}
+		$primaryInstance ??= $modifiedInstances[0];
+
+		if (count($modifiedInstances) > 1) {
+			$this->logger->debug('iTip message contains multiple changed instances; only the master/primary instance is reflected in the invitation email', [
+				'uid' => $iTipMessage->uid,
+				'instanceCount' => count($modifiedInstances),
+			]);
+		}
+
+		/** @var VEvent $vEvent */
+		$vEvent = $primaryInstance['new'];
+		/** @var VEvent|null $oldVevent */
+		$oldVevent = $primaryInstance['old'];
+		$isModified = $oldVevent !== null;
+
+		// we might not have an old event as this could be a new invitation,
+		// or a new recurrence exception
 		$attendee = $this->imipService->getCurrentAttendee($iTipMessage);
 		if ($attendee === null) {
 			$uid = $vEvent->UID ?? 'no UID found';

@@ -40,6 +40,18 @@ class IMipService {
 		'meeting_location' => 'LOCATION'
 	];
 
+	/**
+	 * Properties that, besides RECURRENCE-ID, decide whether a matched
+	 * instance pair counts as "changed".
+	 *
+	 * @var string[]
+	 */
+	private const array INSTANCE_DIFF_PROPERTIES = [
+		'RRULE',
+		'SEQUENCE',
+		'LAST-MODIFIED',
+	];
+
 	public function __construct(
 		private URLGenerator $urlGenerator,
 		private IDBConnection $db,
@@ -149,6 +161,65 @@ private function linkify(?string $url): ?string {
 		return sprintf('<a href="%1$s">%1$s</a>', htmlspecialchars($url));
 	}
 
+	/**
+	 * Compares $new against the previously stored $old calendar and returns
+	 * every VEVENT that changed, paired with its previous version.
+	 *
+	 * Instances are matched by UID and RECURRENCE-ID (the empty string
+	 * standing in for the master event), never by array position, so a
+	 * message carrying several instances (master plus overrides) pairs each
+	 * one with its own prior version rather than an arbitrary old entry.
+	 * A new instance with no matching old one is paired with null.
+	 *
+	 * @return list<array{new: VEvent, old: ?VEvent}>
+	 */
+	public function findModifiedInstances(VCalendar $new, ?VCalendar $old): array {
+		$newEvents = array_values(array_filter(
+			$new->getComponents(),
+			static fn ($component) => $component instanceof VEvent,
+		));
+
+		if ($old === null) {
+			return array_map(
+				static fn (VEvent $event) => ['new' => $event, 'old' => null],
+				$newEvents,
+			);
+		}
+
+		$oldEventsByInstance = [];
+		foreach ($old->getComponents() as $component) {
+			if ($component instanceof VEvent) {
+				$oldEventsByInstance[$this->instanceKey($component)] = $component;
+			}
+		}
+
+		$modified = [];
+		foreach ($newEvents as $newEvent) {
+			$oldEvent = $oldEventsByInstance[$this->instanceKey($newEvent)] ?? null;
+
+			if ($oldEvent !== null && $this->isInstanceUnchanged($newEvent, $oldEvent)) {
+				continue;
+			}
+
+			$modified[] = ['new' => $newEvent, 'old' => $oldEvent];
+		}
+
+		return $modified;
+	}
+
+	private function instanceKey(VEvent $event): string {
+		return self::readPropertyWithDefault($event, 'UID', '') . '#' . self::readPropertyWithDefault($event, 'RECURRENCE-ID', '');
+	}
+
+	private function isInstanceUnchanged(VEvent $newEvent, VEvent $oldEvent): bool {
+		foreach (self::INSTANCE_DIFF_PROPERTIES as $property) {
+			if (self::readPropertyWithDefault($newEvent, $property, '') !== self::readPropertyWithDefault($oldEvent, $property, '')) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	/**
 	 * @param VEvent $vEvent
 	 * @param VEvent|null $oldVEvent

@@ -14,7 +14,6 @@
 use OCA\DAV\CalDAV\BirthdayCalendar\EnablePlugin;
 use OCA\DAV\CalDAV\BirthdayService;
 use OCA\DAV\CalDAV\DefaultCalendarValidator;
-use OCA\DAV\CalDAV\EventComparisonService;
 use OCA\DAV\CalDAV\ICSExportPlugin\ICSExportPlugin;
 use OCA\DAV\CalDAV\Publishing\PublishPlugin;
 use OCA\DAV\CalDAV\Schedule\IMipPlugin;
@@ -358,7 +357,6 @@ public function __construct(
 						\OCP\Server::get(Defaults::class),
 						$userSession,
 						\OCP\Server::get(IMipService::class),
-						\OCP\Server::get(EventComparisonService::class),
 						\OCP\Server::get(\OCP\Mail\Provider\IManager::class),
 						\OCP\Server::get(IEmailValidator::class),
 						\OCP\Server::get(IAccountManager::class),