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/tests/test_ics_dedup.py

@@ -0,0 +1,186 @@
+from datetime import datetime, timedelta, timezone
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from reflector.db.calendar_events import CalendarEvent, calendar_events_controller
+from reflector.db.meetings import meetings
+from reflector.db.rooms import rooms_controller
+from reflector.worker.ics_sync import create_upcoming_meetings_for_event
+
+
+@pytest.mark.asyncio
+async def test_duplicate_calendar_event_does_not_create_duplicate_meeting():
+    """When an aggregated ICS feed contains the same event with different UIDs
+    (e.g. Cal.com UID + Google Calendar UUID), only one meeting should be created."""
+
+    room = await rooms_controller.add(
+        name="dedup-test-room",
+        user_id="test-user",
+        zulip_auto_post=False,
+        zulip_stream="",
+        zulip_topic="",
+        is_locked=False,
+        room_mode="normal",
+        recording_type="cloud",
+        recording_trigger="automatic-2nd-participant",
+        is_shared=False,
+        ics_url="https://calendar.example.com/dedup.ics",
+        ics_enabled=True,
+    )
+
+    now = datetime.now(timezone.utc)
+    start_time = now + timedelta(hours=1)
+    end_time = now + timedelta(hours=2)
+
+    # Create first calendar event (Cal.com UID)
+    event1 = await calendar_events_controller.upsert(
+        CalendarEvent(
+            room_id=room.id,
+            ics_uid="abc123@Cal.com",
+            title="Team Standup",
+            start_time=start_time,
+            end_time=end_time,
+        )
+    )
+
+    # create_window must be before start_time for the function to proceed
+    create_window = now - timedelta(minutes=6)
+
+    # Create meeting for event1
+    with patch(
+        "reflector.worker.ics_sync.create_platform_client"
+    ) as mock_platform_factory:
+        mock_client = AsyncMock()
+        mock_client.create_meeting.return_value = AsyncMock(
+            meeting_id="meeting-1",
+            room_name="dedup-test-room-abc",
+            room_url="https://mock.video/dedup-test-room-abc",
+            host_room_url="https://mock.video/dedup-test-room-abc?host=true",
+        )
+        mock_client.upload_logo = AsyncMock()
+        mock_platform_factory.return_value = mock_client
+
+        await create_upcoming_meetings_for_event(event1, create_window, room)
+
+    # Verify meeting was created
+    from reflector.db import get_database
+
+    results = await get_database().fetch_all(
+        meetings.select().where(meetings.c.room_id == room.id)
+    )
+    assert len(results) == 1, f"Expected 1 meeting, got {len(results)}"
+
+    # Create second calendar event with different UID but same time window (Google Calendar UUID)
+    event2 = await calendar_events_controller.upsert(
+        CalendarEvent(
+            room_id=room.id,
+            ics_uid="550e8400-e29b-41d4-a716-446655440000",
+            title="Team Standup",
+            start_time=start_time,
+            end_time=end_time,
+        )
+    )
+
+    # Try to create meeting for event2 - should be skipped due to dedup
+    with patch(
+        "reflector.worker.ics_sync.create_platform_client"
+    ) as mock_platform_factory:
+        mock_client = AsyncMock()
+        mock_client.create_meeting.return_value = AsyncMock(
+            meeting_id="meeting-2",
+            room_name="dedup-test-room-def",
+            room_url="https://mock.video/dedup-test-room-def",
+            host_room_url="https://mock.video/dedup-test-room-def?host=true",
+        )
+        mock_client.upload_logo = AsyncMock()
+        mock_platform_factory.return_value = mock_client
+
+        await create_upcoming_meetings_for_event(event2, create_window, room)
+
+        # Platform client should NOT have been called for the duplicate
+        mock_client.create_meeting.assert_not_called()
+
+    # Verify still only 1 meeting
+    results = await get_database().fetch_all(
+        meetings.select().where(meetings.c.room_id == room.id)
+    )
+    assert len(results) == 1, f"Expected 1 meeting after dedup, got {len(results)}"
+
+
+@pytest.mark.asyncio
+async def test_different_time_windows_create_separate_meetings():
+    """Events at different times should create separate meetings, even if titles match."""
+
+    room = await rooms_controller.add(
+        name="dedup-diff-time-room",
+        user_id="test-user",
+        zulip_auto_post=False,
+        zulip_stream="",
+        zulip_topic="",
+        is_locked=False,
+        room_mode="normal",
+        recording_type="cloud",
+        recording_trigger="automatic-2nd-participant",
+        is_shared=False,
+        ics_url="https://calendar.example.com/dedup2.ics",
+        ics_enabled=True,
+    )
+
+    now = datetime.now(timezone.utc)
+    create_window = now - timedelta(minutes=6)
+
+    # Event 1: 1-2pm
+    event1 = await calendar_events_controller.upsert(
+        CalendarEvent(
+            room_id=room.id,
+            ics_uid="event-morning@Cal.com",
+            title="Team Standup",
+            start_time=now + timedelta(hours=1),
+            end_time=now + timedelta(hours=2),
+        )
+    )
+
+    # Event 2: 3-4pm (different time)
+    event2 = await calendar_events_controller.upsert(
+        CalendarEvent(
+            room_id=room.id,
+            ics_uid="event-afternoon@Cal.com",
+            title="Team Standup",
+            start_time=now + timedelta(hours=3),
+            end_time=now + timedelta(hours=4),
+        )
+    )
+
+    with patch(
+        "reflector.worker.ics_sync.create_platform_client"
+    ) as mock_platform_factory:
+        mock_client = AsyncMock()
+
+        call_count = 0
+
+        async def mock_create_meeting(room_name_prefix, end_date, room):
+            nonlocal call_count
+            call_count += 1
+            return AsyncMock(
+                meeting_id=f"meeting-{call_count}",
+                room_name=f"dedup-diff-time-room-{call_count}",
+                room_url=f"https://mock.video/dedup-diff-time-room-{call_count}",
+                host_room_url=f"https://mock.video/dedup-diff-time-room-{call_count}?host=true",
+            )
+
+        mock_client.create_meeting = mock_create_meeting
+        mock_client.upload_logo = AsyncMock()
+        mock_platform_factory.return_value = mock_client
+
+        await create_upcoming_meetings_for_event(event1, create_window, room)
+        await create_upcoming_meetings_for_event(event2, create_window, room)
+
+    from reflector.db import get_database
+
+    results = await get_database().fetch_all(
+        meetings.select().where(meetings.c.room_id == room.id)
+    )
+    assert (
+        len(results) == 2
+    ), f"Expected 2 meetings for different times, got {len(results)}"