Method ToggleReaction

backend/Controllers/TasksController.cs:271–294

(int activityId, [FromBody] ToggleReactionDto dto)

    }

    [HttpPost("activities/{activityId}/reactions")]
    public async Task<IActionResult> ToggleReaction(int activityId, [FromBody] ToggleReactionDto dto)
    {
        try
        {
            int userId = GetUserId();
            var reaction = await _taskService.ToggleReactionAsync(activityId, dto.Emoji, userId);

            // Notify board so reactions sync in real-time
            var activity = await _taskService.GetActivityByIdAsync(activityId);
            if (activity != null)
            {
                var task = await _taskService.GetTaskByIdAsync(activity.TaskCardId, userId);
                if (task != null)
                {
                    await _hubContext.Clients.Group($"board_{task.BoardId}")
                        .SendAsync("TaskUpdated", task);
                }
            }

            return Ok(reaction);
        }
        catch (UnauthorizedAccessException) { return Forbid(); }
    }

    [HttpPost("{id}/labels")]
    public async Task<IActionResult> SetLabels(int id, [FromBody] List<int> labelIds)