fix: prevent presence race condition during WebRTC handshake

Add /joining and /joined endpoints to track user join intent before
WebRTC handshake completes. This prevents meetings from being
deactivated while users are still connecting.

- Add pending_joins Redis module with 30s TTL
- Add /joining endpoint (called before WebRTC handshake)
- Add /joined endpoint (called after connection established)
- Check for pending joins before deactivating meetings in worker
- Frontend integration with connectionId per browser tab

server/reflector/presence/__init__.py

@@ -0,0 +1,17 @@
+"""Presence tracking for meetings."""
+
+from reflector.presence.pending_joins import (
+    PENDING_JOIN_PREFIX,
+    PENDING_JOIN_TTL,
+    create_pending_join,
+    delete_pending_join,
+    has_pending_joins,
+)
+
+__all__ = [
+    "PENDING_JOIN_PREFIX",
+    "PENDING_JOIN_TTL",
+    "create_pending_join",
+    "delete_pending_join",
+    "has_pending_joins",
+]

server/reflector/presence/pending_joins.py

@@ -0,0 +1,59 @@
+"""Track pending join intents in Redis.
+
+When a user signals intent to join a meeting (before WebRTC handshake completes),
+we store a pending join record. This prevents the meeting from being deactivated
+while users are still connecting.
+"""
+
+import time
+
+from redis.asyncio import Redis
+
+from reflector.logger import logger
+
+PENDING_JOIN_TTL = 30  # seconds
+PENDING_JOIN_PREFIX = "pending_join"
+# Max keys to scan per Redis SCAN iteration
+SCAN_BATCH_SIZE = 100
+
+
+async def create_pending_join(redis: Redis, meeting_id: str, user_id: str) -> None:
+    """Create a pending join record. Called before WebRTC handshake."""
+    key = f"{PENDING_JOIN_PREFIX}:{meeting_id}:{user_id}"
+    log = logger.bind(meeting_id=meeting_id, user_id=user_id, key=key)
+    await redis.setex(key, PENDING_JOIN_TTL, str(time.time()))
+    log.debug("Created pending join")
+
+
+async def delete_pending_join(redis: Redis, meeting_id: str, user_id: str) -> None:
+    """Delete pending join. Called after WebRTC connection established."""
+    key = f"{PENDING_JOIN_PREFIX}:{meeting_id}:{user_id}"
+    log = logger.bind(meeting_id=meeting_id, user_id=user_id, key=key)
+    await redis.delete(key)
+    log.debug("Deleted pending join")
+
+
+async def has_pending_joins(redis: Redis, meeting_id: str) -> bool:
+    """Check if meeting has any pending joins.
+
+    Uses Redis SCAN to iterate through all keys matching the pattern.
+    Properly iterates until cursor returns 0 to ensure all keys are checked.
+    """
+    pattern = f"{PENDING_JOIN_PREFIX}:{meeting_id}:*"
+    log = logger.bind(meeting_id=meeting_id, pattern=pattern)
+
+    cursor = 0
+    iterations = 0
+    while True:
+        cursor, keys = await redis.scan(
+            cursor=cursor, match=pattern, count=SCAN_BATCH_SIZE
+        )
+        iterations += 1
+        if keys:
+            log.debug("Found pending joins", count=len(keys), iterations=iterations)
+            return True
+        if cursor == 0:
+            break
+
+    log.debug("No pending joins found", iterations=iterations)
+    return False

server/reflector/views/rooms.py

@@ -1,4 +1,3 @@
-import logging
 from datetime import datetime, timedelta, timezone
 from enum import Enum
 from typing import Annotated, Any, Literal, Optional
@@ -14,16 +13,17 @@ from reflector.db import get_database
 from reflector.db.calendar_events import calendar_events_controller
 from reflector.db.meetings import meetings_controller
 from reflector.db.rooms import rooms_controller
-from reflector.redis_cache import RedisAsyncLock
+from reflector.logger import logger
+from reflector.presence.pending_joins import create_pending_join, delete_pending_join
+from reflector.redis_cache import RedisAsyncLock, get_async_redis_client
 from reflector.schemas.platform import Platform
 from reflector.services.ics_sync import ics_sync_service
 from reflector.settings import settings
+from reflector.utils.string import NonEmptyString
 from reflector.utils.url import add_query_param
 from reflector.video_platforms.factory import create_platform_client
 from reflector.worker.webhook import test_webhook
 
-logger = logging.getLogger(__name__)
-
 
 class Room(BaseModel):
     id: str
@@ -597,3 +597,112 @@ async def rooms_join_meeting(
         meeting.room_url = add_query_param(meeting.room_url, "t", token)
 
     return meeting
+
+
+class JoiningRequest(BaseModel):
+    """Request body for /joining and /joined endpoints."""
+
+    connection_id: NonEmptyString
+    """Unique identifier for this connection. Should be a UUID generated by the client.
+    Must be the same value for both /joining and /joined calls from the same tab."""
+
+
+class JoiningResponse(BaseModel):
+    status: Literal["ok"]
+
+
+def _get_pending_join_key(
+    user: Optional[auth.UserInfo], connection_id: NonEmptyString
+) -> str:
+    """Get a unique key for pending join tracking.
+
+    Uses user ID for authenticated users, connection_id for anonymous users.
+    This ensures each browser tab has its own unique pending join record.
+    """
+    if user:
+        return f"{user['sub']}:{connection_id}"
+    return f"anon:{connection_id}"
+
+
+@router.post(
+    "/rooms/{room_name}/meetings/{meeting_id}/joining", response_model=JoiningResponse
+)
+async def meeting_joining(
+    room_name: str,
+    meeting_id: str,
+    body: JoiningRequest,
+    user: Annotated[Optional[auth.UserInfo], Depends(auth.current_user_optional)],
+) -> JoiningResponse:
+    """Signal intent to join meeting. Called before WebRTC handshake starts.
+
+    This creates a pending join record that prevents the meeting from being
+    deactivated while the WebRTC handshake is in progress. The record expires
+    automatically after 30 seconds if the connection is not established.
+    """
+    log = logger.bind(
+        room_name=room_name, meeting_id=meeting_id, connection_id=body.connection_id
+    )
+
+    room = await rooms_controller.get_by_name(room_name)
+    if not room:
+        raise HTTPException(status_code=404, detail="Room not found")
+
+    meeting = await meetings_controller.get_by_id(meeting_id, room=room)
+    if not meeting:
+        raise HTTPException(status_code=404, detail="Meeting not found")
+
+    if not meeting.is_active:
+        raise HTTPException(status_code=400, detail="Meeting is not active")
+
+    join_key = _get_pending_join_key(user, body.connection_id)
+
+    redis = await get_async_redis_client()
+    try:
+        await create_pending_join(redis, meeting_id, join_key)
+        log.debug("Created pending join intent", join_key=join_key)
+    finally:
+        await redis.aclose()
+
+    return JoiningResponse(status="ok")
+
+
+@router.post(
+    "/rooms/{room_name}/meetings/{meeting_id}/joined", response_model=JoiningResponse
+)
+async def meeting_joined(
+    room_name: str,
+    meeting_id: str,
+    body: JoiningRequest,
+    user: Annotated[Optional[auth.UserInfo], Depends(auth.current_user_optional)],
+) -> JoiningResponse:
+    """Signal that WebRTC connection is established.
+
+    This clears the pending join record, confirming the user has successfully
+    connected to the meeting. Safe to call even if meeting was deactivated
+    during the handshake (idempotent cleanup).
+    """
+    log = logger.bind(
+        room_name=room_name, meeting_id=meeting_id, connection_id=body.connection_id
+    )
+
+    room = await rooms_controller.get_by_name(room_name)
+    if not room:
+        raise HTTPException(status_code=404, detail="Room not found")
+
+    meeting = await meetings_controller.get_by_id(meeting_id, room=room)
+    if not meeting:
+        raise HTTPException(status_code=404, detail="Meeting not found")
+
+    # Note: We don't check is_active here - the /joined call is a cleanup operation
+    # and should succeed even if the meeting was deactivated during the handshake
+
+    join_key = _get_pending_join_key(user, body.connection_id)
+
+    redis = await get_async_redis_client()
+    try:
+        await delete_pending_join(redis, meeting_id, join_key)
+        log.debug("Cleared pending join intent", join_key=join_key)
+    finally:
+        await redis.aclose()
+
+    return JoiningResponse(status="ok")

server/reflector/worker/process.py

@@ -31,9 +31,10 @@ from reflector.pipelines.main_multitrack_pipeline import (
     task_pipeline_multitrack_process,
 )
 from reflector.pipelines.topic_processing import EmptyPipeline
+from reflector.presence.pending_joins import has_pending_joins
 from reflector.processors import AudioFileWriterProcessor
 from reflector.processors.audio_waveform_processor import AudioWaveformProcessor
-from reflector.redis_cache import RedisAsyncLock
+from reflector.redis_cache import RedisAsyncLock, get_async_redis_client
 from reflector.settings import settings
 from reflector.storage import get_transcripts_storage
 from reflector.utils.daily import (
@@ -869,6 +870,18 @@ async def process_meetings():
                     logger_.debug("Meeting not yet started, keep it")
 
                 if should_deactivate:
+                    # Check for pending joins before deactivating
+                    # Users might be in the process of connecting via WebRTC
+                    redis = await get_async_redis_client()
+                    try:
+                        if await has_pending_joins(redis, meeting.id):
+                            logger_.info(
+                                "Meeting has pending joins, skipping deactivation"
+                            )
+                            continue
+                    finally:
+                        await redis.aclose()
+
                     await meetings_controller.update_meeting(
                         meeting.id, is_active=False
                     )

server/tests/test_joining_endpoint.py

@@ -0,0 +1,362 @@
+"""Integration tests for /joining and /joined endpoints.
+
+Tests for the join intent tracking to prevent race conditions during
+WebRTC handshake when users join meetings.
+"""
+
+from datetime import datetime, timedelta, timezone
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from reflector.db.meetings import Meeting
+from reflector.presence.pending_joins import PENDING_JOIN_PREFIX
+
+TEST_CONNECTION_ID = "test-connection-uuid-12345"
+
+
+@pytest.fixture
+def mock_room():
+    """Mock room object."""
+    from reflector.db.rooms import Room
+
+    return Room(
+        id="room-123",
+        name="test-room",
+        user_id="owner-user",
+        created_at=datetime.now(timezone.utc),
+        zulip_auto_post=False,
+        zulip_stream="",
+        zulip_topic="",
+        is_locked=False,
+        room_mode="normal",
+        recording_type="cloud",
+        recording_trigger="automatic",
+        is_shared=True,
+        platform="daily",
+        skip_consent=False,
+    )
+
+
+@pytest.fixture
+def mock_meeting():
+    """Mock meeting object."""
+    now = datetime.now(timezone.utc)
+    return Meeting(
+        id="meeting-456",
+        room_id="room-123",
+        room_name="test-room-20251118120000",
+        room_url="https://daily.co/test-room-20251118120000",
+        host_room_url="https://daily.co/test-room-20251118120000?t=host",
+        platform="daily",
+        num_clients=0,
+        is_active=True,
+        start_date=now,
+        end_date=now + timedelta(hours=1),
+    )
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_joining_endpoint_creates_pending_join(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+    authenticated_client,
+):
+    """Test that /joining endpoint creates pending join in Redis."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.setex = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    response = await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 200
+    assert response.json() == {"status": "ok"}
+
+    # Verify Redis setex was called with correct key pattern
+    mock_redis.setex.assert_called_once()
+    call_args = mock_redis.setex.call_args[0]
+    assert call_args[0].startswith(f"{PENDING_JOIN_PREFIX}:{mock_meeting.id}:")
+    assert TEST_CONNECTION_ID in call_args[0]
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_joined_endpoint_deletes_pending_join(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+    authenticated_client,
+):
+    """Test that /joined endpoint deletes pending join from Redis."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.delete = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    response = await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joined",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 200
+    assert response.json() == {"status": "ok"}
+
+    # Verify Redis delete was called with correct key pattern
+    mock_redis.delete.assert_called_once()
+    call_args = mock_redis.delete.call_args[0]
+    assert call_args[0].startswith(f"{PENDING_JOIN_PREFIX}:{mock_meeting.id}:")
+    assert TEST_CONNECTION_ID in call_args[0]
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+async def test_joining_endpoint_room_not_found(
+    mock_get_room,
+    client,
+    authenticated_client,
+):
+    """Test that /joining returns 404 when room not found."""
+    mock_get_room.return_value = None
+
+    response = await client.post(
+        "/rooms/nonexistent-room/meetings/meeting-123/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 404
+    assert response.json()["detail"] == "Room not found"
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+async def test_joining_endpoint_meeting_not_found(
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    client,
+    authenticated_client,
+):
+    """Test that /joining returns 404 when meeting not found."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = None
+
+    response = await client.post(
+        f"/rooms/{mock_room.name}/meetings/nonexistent-meeting/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 404
+    assert response.json()["detail"] == "Meeting not found"
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+async def test_joining_endpoint_meeting_not_active(
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+    authenticated_client,
+):
+    """Test that /joining returns 400 when meeting is not active."""
+    mock_get_room.return_value = mock_room
+    inactive_meeting = mock_meeting.model_copy(update={"is_active": False})
+    mock_get_meeting.return_value = inactive_meeting
+
+    response = await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 400
+    assert response.json()["detail"] == "Meeting is not active"
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_joining_endpoint_anonymous_user(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+):
+    """Test that /joining works for anonymous users with unique connection_id."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.setex = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    response = await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    assert response.status_code == 200
+    assert response.json() == {"status": "ok"}
+
+    # Verify Redis setex was called with "anon:" prefix and connection_id
+    call_args = mock_redis.setex.call_args[0]
+    assert ":anon:" in call_args[0]
+    assert TEST_CONNECTION_ID in call_args[0]
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_joining_endpoint_redis_closed_on_success(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+    authenticated_client,
+):
+    """Test that Redis connection is closed after successful operation."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.setex = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": TEST_CONNECTION_ID},
+    )
+
+    mock_redis.aclose.assert_called_once()
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_joining_endpoint_redis_closed_on_error(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+    authenticated_client,
+):
+    """Test that Redis connection is closed even when operation fails."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.setex = AsyncMock(side_effect=Exception("Redis error"))
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    with pytest.raises(Exception):
+        await client.post(
+            f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+            json={"connection_id": TEST_CONNECTION_ID},
+        )
+
+    mock_redis.aclose.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_joining_endpoint_requires_connection_id(
+    client,
+):
+    """Test that /joining returns 422 when connection_id is missing."""
+    response = await client.post(
+        "/rooms/test-room/meetings/meeting-123/joining",
+        json={},
+    )
+
+    assert response.status_code == 422  # Validation error
+
+
+@pytest.mark.asyncio
+async def test_joining_endpoint_rejects_empty_connection_id(
+    client,
+):
+    """Test that /joining returns 422 when connection_id is empty string."""
+    response = await client.post(
+        "/rooms/test-room/meetings/meeting-123/joining",
+        json={"connection_id": ""},
+    )
+
+    assert response.status_code == 422  # Validation error (NonEmptyString)
+
+
+@pytest.mark.asyncio
+@patch("reflector.views.rooms.rooms_controller.get_by_name")
+@patch("reflector.views.rooms.meetings_controller.get_by_id")
+@patch("reflector.views.rooms.get_async_redis_client")
+async def test_different_connection_ids_create_different_keys(
+    mock_get_redis,
+    mock_get_meeting,
+    mock_get_room,
+    mock_room,
+    mock_meeting,
+    client,
+):
+    """Test that different connection_ids create different Redis keys."""
+    mock_get_room.return_value = mock_room
+    mock_get_meeting.return_value = mock_meeting
+
+    mock_redis = AsyncMock()
+    mock_redis.setex = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    # First connection
+    await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": "connection-1"},
+    )
+    key1 = mock_redis.setex.call_args[0][0]
+
+    mock_redis.setex.reset_mock()
+
+    # Second connection (different tab)
+    await client.post(
+        f"/rooms/{mock_room.name}/meetings/{mock_meeting.id}/joining",
+        json={"connection_id": "connection-2"},
+    )
+    key2 = mock_redis.setex.call_args[0][0]
+
+    # Keys should be different
+    assert key1 != key2
+    assert "connection-1" in key1
+    assert "connection-2" in key2

server/tests/test_pending_joins.py

@@ -0,0 +1,153 @@
+"""Tests for pending joins Redis helper functions.
+
+TDD tests for tracking join intent to prevent race conditions during
+WebRTC handshake when users join meetings.
+"""
+
+from unittest.mock import AsyncMock
+
+import pytest
+
+from reflector.presence.pending_joins import (
+    PENDING_JOIN_PREFIX,
+    PENDING_JOIN_TTL,
+    create_pending_join,
+    delete_pending_join,
+    has_pending_joins,
+)
+
+
+@pytest.fixture
+def mock_redis():
+    """Mock async Redis client."""
+    redis = AsyncMock()
+    redis.setex = AsyncMock()
+    redis.delete = AsyncMock()
+    redis.scan = AsyncMock(return_value=(0, []))
+    return redis
+
+
+@pytest.mark.asyncio
+async def test_create_pending_join_sets_key_with_ttl(mock_redis):
+    """Test that create_pending_join stores key with correct TTL."""
+    meeting_id = "meeting-123"
+    user_id = "user-456"
+
+    await create_pending_join(mock_redis, meeting_id, user_id)
+
+    expected_key = f"{PENDING_JOIN_PREFIX}:{meeting_id}:{user_id}"
+    mock_redis.setex.assert_called_once()
+    call_args = mock_redis.setex.call_args
+    assert call_args[0][0] == expected_key
+    assert call_args[0][1] == PENDING_JOIN_TTL
+    # Value should be a timestamp string
+    assert call_args[0][2] is not None
+
+
+@pytest.mark.asyncio
+async def test_delete_pending_join_removes_key(mock_redis):
+    """Test that delete_pending_join removes the key."""
+    meeting_id = "meeting-123"
+    user_id = "user-456"
+
+    await delete_pending_join(mock_redis, meeting_id, user_id)
+
+    expected_key = f"{PENDING_JOIN_PREFIX}:{meeting_id}:{user_id}"
+    mock_redis.delete.assert_called_once_with(expected_key)
+
+
+@pytest.mark.asyncio
+async def test_has_pending_joins_returns_false_when_no_keys(mock_redis):
+    """Test has_pending_joins returns False when no matching keys."""
+    mock_redis.scan.return_value = (0, [])
+
+    result = await has_pending_joins(mock_redis, "meeting-123")
+
+    assert result is False
+    mock_redis.scan.assert_called_once()
+    call_kwargs = mock_redis.scan.call_args.kwargs
+    assert call_kwargs["match"] == f"{PENDING_JOIN_PREFIX}:meeting-123:*"
+
+
+@pytest.mark.asyncio
+async def test_has_pending_joins_returns_true_when_keys_exist(mock_redis):
+    """Test has_pending_joins returns True when matching keys found."""
+    mock_redis.scan.return_value = (0, [b"pending_join:meeting-123:user-1"])
+
+    result = await has_pending_joins(mock_redis, "meeting-123")
+
+    assert result is True
+
+
+@pytest.mark.asyncio
+async def test_has_pending_joins_scans_with_correct_pattern(mock_redis):
+    """Test has_pending_joins uses correct scan pattern."""
+    meeting_id = "meeting-abc-def"
+    mock_redis.scan.return_value = (0, [])
+
+    await has_pending_joins(mock_redis, meeting_id)
+
+    expected_pattern = f"{PENDING_JOIN_PREFIX}:{meeting_id}:*"
+    mock_redis.scan.assert_called_once()
+    call_kwargs = mock_redis.scan.call_args.kwargs
+    assert call_kwargs["match"] == expected_pattern
+    assert call_kwargs["count"] == 100
+
+
+@pytest.mark.asyncio
+async def test_multiple_users_pending_joins(mock_redis):
+    """Test that multiple users can have pending joins for same meeting."""
+    meeting_id = "meeting-123"
+    # Simulate two pending joins
+    mock_redis.scan.return_value = (
+        0,
+        [b"pending_join:meeting-123:user-1", b"pending_join:meeting-123:user-2"],
+    )
+
+    result = await has_pending_joins(mock_redis, meeting_id)
+
+    assert result is True
+
+
+@pytest.mark.asyncio
+async def test_pending_join_ttl_value():
+    """Test that PENDING_JOIN_TTL has expected value."""
+    # 30 seconds should be enough for WebRTC handshake but not too long
+    assert PENDING_JOIN_TTL == 30
+
+
+@pytest.mark.asyncio
+async def test_pending_join_prefix_value():
+    """Test that PENDING_JOIN_PREFIX has expected value."""
+    assert PENDING_JOIN_PREFIX == "pending_join"
+
+
+@pytest.mark.asyncio
+async def test_has_pending_joins_multi_iteration_scan_no_keys(mock_redis):
+    """Test has_pending_joins iterates until cursor returns 0."""
+    # Simulate multi-iteration scan: cursor 100 -> cursor 50 -> cursor 0
+    mock_redis.scan.side_effect = [
+        (100, []),  # First iteration, no keys, continue
+        (50, []),  # Second iteration, no keys, continue
+        (0, []),  # Third iteration, cursor 0, done
+    ]
+
+    result = await has_pending_joins(mock_redis, "meeting-123")
+
+    assert result is False
+    assert mock_redis.scan.call_count == 3
+
+
+@pytest.mark.asyncio
+async def test_has_pending_joins_multi_iteration_finds_key_later(mock_redis):
+    """Test has_pending_joins finds key on second iteration."""
+    # Simulate finding key on second scan iteration
+    mock_redis.scan.side_effect = [
+        (100, []),  # First iteration, no keys
+        (0, [b"pending_join:meeting-123:user-1"]),  # Second iteration, found key
+    ]
+
+    result = await has_pending_joins(mock_redis, "meeting-123")
+
+    assert result is True
+    assert mock_redis.scan.call_count == 2

server/tests/test_process_meetings_pending_joins.py

@@ -0,0 +1,241 @@
+"""Tests for process_meetings pending joins check.
+
+Tests that process_meetings correctly skips deactivation when
+pending joins exist for a meeting.
+"""
+
+from datetime import datetime, timedelta, timezone
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from reflector.db.meetings import Meeting
+
+
+def _get_process_meetings_fn():
+    """Get the underlying async function without Celery/asynctask decorators."""
+    from reflector.worker import process
+
+    fn = process.process_meetings
+    # Get through both decorator layers (@shared_task and @asynctask)
+    if hasattr(fn, "__wrapped__"):
+        fn = fn.__wrapped__
+    if hasattr(fn, "__wrapped__"):
+        fn = fn.__wrapped__
+    return fn
+
+
+@pytest.fixture
+def mock_active_meeting():
+    """Mock an active meeting that should be considered for deactivation."""
+    now = datetime.now(timezone.utc)
+    return Meeting(
+        id="meeting-123",
+        room_id="room-456",
+        room_name="test-room-20251118120000",
+        room_url="https://daily.co/test-room-20251118120000",
+        host_room_url="https://daily.co/test-room-20251118120000?t=host",
+        platform="daily",
+        num_clients=0,
+        is_active=True,
+        start_date=now - timedelta(hours=1),
+        end_date=now - timedelta(minutes=30),  # Already ended
+    )
+
+
+@pytest.mark.asyncio
+@patch("reflector.worker.process.meetings_controller.get_all_active")
+@patch("reflector.worker.process.RedisAsyncLock")
+@patch("reflector.worker.process.create_platform_client")
+@patch("reflector.worker.process.get_async_redis_client")
+@patch("reflector.worker.process.has_pending_joins")
+@patch("reflector.worker.process.meetings_controller.update_meeting")
+async def test_process_meetings_skips_deactivation_with_pending_joins(
+    mock_update_meeting,
+    mock_has_pending_joins,
+    mock_get_redis,
+    mock_create_client,
+    mock_redis_lock_class,
+    mock_get_all_active,
+    mock_active_meeting,
+):
+    """Test that process_meetings skips deactivation when pending joins exist."""
+    process_meetings = _get_process_meetings_fn()
+
+    mock_get_all_active.return_value = [mock_active_meeting]
+
+    # Mock lock acquired
+    mock_lock_instance = AsyncMock()
+    mock_lock_instance.acquired = True
+    mock_lock_instance.__aenter__ = AsyncMock(return_value=mock_lock_instance)
+    mock_lock_instance.__aexit__ = AsyncMock()
+    mock_redis_lock_class.return_value = mock_lock_instance
+
+    # Mock platform client - no active sessions, but had sessions (triggers deactivation)
+    mock_daily_client = AsyncMock()
+    mock_session = AsyncMock()
+    mock_session.ended_at = datetime.now(timezone.utc)  # Session ended
+    mock_daily_client.get_room_sessions = AsyncMock(return_value=[mock_session])
+    mock_create_client.return_value = mock_daily_client
+
+    # Mock Redis client
+    mock_redis = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    # Mock pending joins exist
+    mock_has_pending_joins.return_value = True
+
+    await process_meetings()
+
+    # Verify has_pending_joins was called
+    mock_has_pending_joins.assert_called_once_with(mock_redis, mock_active_meeting.id)
+
+    # Verify meeting was NOT deactivated
+    mock_update_meeting.assert_not_called()
+
+    # Verify Redis was closed
+    mock_redis.aclose.assert_called_once()
+
+
+@pytest.mark.asyncio
+@patch("reflector.worker.process.meetings_controller.get_all_active")
+@patch("reflector.worker.process.RedisAsyncLock")
+@patch("reflector.worker.process.create_platform_client")
+@patch("reflector.worker.process.get_async_redis_client")
+@patch("reflector.worker.process.has_pending_joins")
+@patch("reflector.worker.process.meetings_controller.update_meeting")
+async def test_process_meetings_deactivates_without_pending_joins(
+    mock_update_meeting,
+    mock_has_pending_joins,
+    mock_get_redis,
+    mock_create_client,
+    mock_redis_lock_class,
+    mock_get_all_active,
+    mock_active_meeting,
+):
+    """Test that process_meetings deactivates when no pending joins."""
+    process_meetings = _get_process_meetings_fn()
+
+    mock_get_all_active.return_value = [mock_active_meeting]
+
+    # Mock lock acquired
+    mock_lock_instance = AsyncMock()
+    mock_lock_instance.acquired = True
+    mock_lock_instance.__aenter__ = AsyncMock(return_value=mock_lock_instance)
+    mock_lock_instance.__aexit__ = AsyncMock()
+    mock_redis_lock_class.return_value = mock_lock_instance
+
+    # Mock platform client - no active sessions, but had sessions
+    mock_daily_client = AsyncMock()
+    mock_session = AsyncMock()
+    mock_session.ended_at = datetime.now(timezone.utc)
+    mock_daily_client.get_room_sessions = AsyncMock(return_value=[mock_session])
+    mock_create_client.return_value = mock_daily_client
+
+    # Mock Redis client
+    mock_redis = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    # Mock no pending joins
+    mock_has_pending_joins.return_value = False
+
+    await process_meetings()
+
+    # Verify meeting was deactivated
+    mock_update_meeting.assert_called_once_with(mock_active_meeting.id, is_active=False)
+
+
+@pytest.mark.asyncio
+@patch("reflector.worker.process.meetings_controller.get_all_active")
+@patch("reflector.worker.process.RedisAsyncLock")
+@patch("reflector.worker.process.create_platform_client")
+async def test_process_meetings_no_check_when_active_sessions(
+    mock_create_client,
+    mock_redis_lock_class,
+    mock_get_all_active,
+    mock_active_meeting,
+):
+    """Test that pending joins check is skipped when there are active sessions."""
+    process_meetings = _get_process_meetings_fn()
+
+    mock_get_all_active.return_value = [mock_active_meeting]
+
+    # Mock lock acquired
+    mock_lock_instance = AsyncMock()
+    mock_lock_instance.acquired = True
+    mock_lock_instance.__aenter__ = AsyncMock(return_value=mock_lock_instance)
+    mock_lock_instance.__aexit__ = AsyncMock()
+    mock_redis_lock_class.return_value = mock_lock_instance
+
+    # Mock platform client - has active session
+    mock_daily_client = AsyncMock()
+    mock_session = AsyncMock()
+    mock_session.ended_at = None  # Still active
+    mock_daily_client.get_room_sessions = AsyncMock(return_value=[mock_session])
+    mock_create_client.return_value = mock_daily_client
+
+    with (
+        patch("reflector.worker.process.get_async_redis_client") as mock_get_redis,
+        patch("reflector.worker.process.has_pending_joins") as mock_has_pending_joins,
+        patch(
+            "reflector.worker.process.meetings_controller.update_meeting"
+        ) as mock_update_meeting,
+    ):
+        await process_meetings()
+
+        # Verify pending joins check was NOT called (no need - active sessions exist)
+        mock_has_pending_joins.assert_not_called()
+
+        # Verify meeting was NOT deactivated
+        mock_update_meeting.assert_not_called()
+
+
+@pytest.mark.asyncio
+@patch("reflector.worker.process.meetings_controller.get_all_active")
+@patch("reflector.worker.process.RedisAsyncLock")
+@patch("reflector.worker.process.create_platform_client")
+@patch("reflector.worker.process.get_async_redis_client")
+@patch("reflector.worker.process.has_pending_joins")
+@patch("reflector.worker.process.meetings_controller.update_meeting")
+async def test_process_meetings_closes_redis_even_on_continue(
+    mock_update_meeting,
+    mock_has_pending_joins,
+    mock_get_redis,
+    mock_create_client,
+    mock_redis_lock_class,
+    mock_get_all_active,
+    mock_active_meeting,
+):
+    """Test that Redis connection is always closed, even when skipping deactivation."""
+    process_meetings = _get_process_meetings_fn()
+
+    mock_get_all_active.return_value = [mock_active_meeting]
+
+    # Mock lock acquired
+    mock_lock_instance = AsyncMock()
+    mock_lock_instance.acquired = True
+    mock_lock_instance.__aenter__ = AsyncMock(return_value=mock_lock_instance)
+    mock_lock_instance.__aexit__ = AsyncMock()
+    mock_redis_lock_class.return_value = mock_lock_instance
+
+    # Mock platform client - no active sessions
+    mock_daily_client = AsyncMock()
+    mock_session = AsyncMock()
+    mock_session.ended_at = datetime.now(timezone.utc)
+    mock_daily_client.get_room_sessions = AsyncMock(return_value=[mock_session])
+    mock_create_client.return_value = mock_daily_client
+
+    # Mock Redis client
+    mock_redis = AsyncMock()
+    mock_redis.aclose = AsyncMock()
+    mock_get_redis.return_value = mock_redis
+
+    # Mock pending joins exist (will trigger continue)
+    mock_has_pending_joins.return_value = True
+
+    await process_meetings()
+
+    # Verify Redis was closed
+    mock_redis.aclose.assert_called_once()

www/app/[roomName]/components/DailyRoom.tsx

@@ -25,6 +25,8 @@ import { useConsentDialog } from "../../lib/consent";
 import {
   useRoomJoinMeeting,
   useMeetingStartRecording,
+  useMeetingJoining,
+  useMeetingJoined,
 } from "../../lib/apiHooks";
 import { omit } from "remeda";
 import {
@@ -187,8 +189,14 @@ export default function DailyRoom({ meeting, room }: DailyRoomProps) {
   const [container, setContainer] = useState<HTMLDivElement | null>(null);
   const joinMutation = useRoomJoinMeeting();
   const startRecordingMutation = useMeetingStartRecording();
+  const joiningMutation = useMeetingJoining();
+  const joinedMutation = useMeetingJoined();
   const [joinedMeeting, setJoinedMeeting] = useState<Meeting | null>(null);
 
+  // Generate a stable connection ID for this component instance
+  // Used to track pending joins per browser tab (prevents key collision for anonymous users)
+  const connectionId = useMemo(() => crypto.randomUUID(), []);
+
   // Generate deterministic instanceIds so all participants use SAME IDs
   const cloudInstanceId = parseNonEmptyString(meeting.id);
   const rawTracksInstanceId = parseNonEmptyString(
@@ -249,6 +257,28 @@ export default function DailyRoom({ meeting, room }: DailyRoomProps) {
   );
 
   const handleFrameJoinMeeting = useCallback(() => {
+    // Signal that WebRTC connection is established
+    // This clears the pending join intent, confirming successful connection
+    joinedMutation.mutate(
+      {
+        params: {
+          path: {
+            room_name: roomName,
+            meeting_id: meeting.id,
+          },
+        },
+        body: {
+          connection_id: connectionId,
+        },
+      },
+      {
+        onError: (error: unknown) => {
+          // Non-blocking: log but don't fail - this is cleanup, not critical
+          console.warn("Failed to signal joined:", error);
+        },
+      },
+    );
+
     if (meeting.recording_type === "cloud") {
       console.log("Starting dual recording via REST API", {
         cloudInstanceId,
@@ -310,6 +340,9 @@ export default function DailyRoom({ meeting, room }: DailyRoomProps) {
   }, [
     meeting.recording_type,
     meeting.id,
+    roomName,
+    connectionId,
+    joinedMutation,
     startRecordingMutation,
     cloudInstanceId,
     rawTracksInstanceId,
@@ -328,8 +361,28 @@ export default function DailyRoom({ meeting, room }: DailyRoomProps) {
 
   useEffect(() => {
     if (!frame || !roomUrl) return;
-    frame
+
-      .join({
+    const joinRoom = async () => {
+      // Signal intent to join before WebRTC handshake starts
+      // This prevents race condition where meeting is deactivated during handshake
+      try {
+        await joiningMutation.mutateAsync({
+          params: {
+            path: {
+              room_name: roomName,
+              meeting_id: meeting.id,
+            },
+          },
+          body: {
+            connection_id: connectionId,
+          },
+        });
+      } catch (error) {
+        // Non-blocking: log but continue with join
+        console.warn("Failed to signal joining intent:", error);
+      }
+
+      await frame.join({
         url: roomUrl,
         sendSettings: {
           video: {
@@ -341,9 +394,13 @@ export default function DailyRoom({ meeting, room }: DailyRoomProps) {
           },
           // Note: screenVideo intentionally not configured to preserve full quality for screen shares
         },
-      })
+      });
-      .catch(console.error.bind(console, "Failed to join daily room:"));
+    };
-  }, [frame, roomUrl]);
+
+    joinRoom().catch(console.error.bind(console, "Failed to join daily room:"));
+    // joiningMutation excluded from deps - it's a stable hook reference
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [frame, roomUrl, roomName, meeting.id, connectionId]);
 
   useEffect(() => {
     setCustomTrayButton(

www/app/lib/apiHooks.ts

@@ -807,6 +807,26 @@ export function useRoomJoinMeeting() {
   );
 }
 
+// Presence race fix endpoints (not yet in OpenAPI spec)
+// These signal join intent to prevent race conditions during WebRTC handshake
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function useMeetingJoining(): any {
+  return ($api as any).useMutation(
+    "post",
+    "/v1/rooms/{room_name}/meetings/{meeting_id}/joining",
+    {},
+  );
+}
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function useMeetingJoined(): any {
+  return ($api as any).useMutation(
+    "post",
+    "/v1/rooms/{room_name}/meetings/{meeting_id}/joined",
+    {},
+  );
+}
+
 export function useRoomIcsSync() {
   const { setError } = useError();