fix: prevent duplicate meetings from aggregated ICS calendar feeds

When Cal.com events appear in an aggregated ICS feed, the same event
gets two different UIDs (one from Cal.com, one from Google Calendar).
This caused duplicate meetings to be created for the same time slot.

Add time-window dedup check in create_upcoming_meetings_for_event:
after verifying no meeting exists for the calendar_event_id, also check
if a meeting already exists for the same room + start_date + end_date.

server/reflector/db/meetings.py

@@ -346,6 +346,27 @@ class MeetingController:
             return None
         return Meeting(**result)
 
+    async def get_by_room_and_time_window(
+        self, room: Room, start_date: datetime, end_date: datetime
+    ) -> Meeting | None:
+        """Check if a meeting already exists for this room with the same time window."""
+        query = (
+            meetings.select()
+            .where(
+                sa.and_(
+                    meetings.c.room_id == room.id,
+                    meetings.c.start_date == start_date,
+                    meetings.c.end_date == end_date,
+                    meetings.c.is_active,
+                )
+            )
+            .limit(1)
+        )
+        result = await get_database().fetch_one(query)
+        if not result:
+            return None
+        return Meeting(**result)
+
     async def update_meeting(self, meeting_id: str, **kwargs):
         query = meetings.update().where(meetings.c.id == meeting_id).values(**kwargs)
         await get_database().execute(query)

server/reflector/worker/ics_sync.py

@@ -94,6 +94,21 @@ async def create_upcoming_meetings_for_event(event, create_window, room: Room):
     if existing_meeting:
         return
 
+    # Prevent duplicate meetings from aggregated calendar feeds
+    # (e.g. same event appears with different UIDs from Cal.com and Google Calendar)
+    end_date = event.end_time or (event.start_time + MEETING_DEFAULT_DURATION)
+    existing_by_time = await meetings_controller.get_by_room_and_time_window(
+        room, event.start_time, end_date
+    )
+    if existing_by_time:
+        logger.info(
+            "Skipping duplicate calendar event - meeting already exists for this time window",
+            room_id=room.id,
+            event_id=event.id,
+            existing_meeting_id=existing_by_time.id,
+        )
+        return
+
     logger.info(
         "Pre-creating meeting for calendar event",
         room_id=room.id,
@@ -102,8 +117,6 @@ async def create_upcoming_meetings_for_event(event, create_window, room: Room):
     )
 
     try:
-        end_date = event.end_time or (event.start_time + MEETING_DEFAULT_DURATION)
-
         client = create_platform_client(room.platform)
 
         meeting_data = await client.create_meeting(