feat(backend): Add SignalR real-time notifications for Sprint events - Sprint 2 Story 3 Task 5

Implemented comprehensive SignalR notifications for Sprint lifecycle events.

Features:
- Extended IRealtimeNotificationService with 5 Sprint notification methods
- Implemented Sprint notification service methods in RealtimeNotificationService
- Created SprintEventHandlers to handle all 5 Sprint domain events
- Updated UpdateSprintCommandHandler to publish SprintUpdatedEvent
- SignalR events broadcast to both project and tenant groups

Sprint Events Implemented:
1. SprintCreated - New sprint created
2. SprintUpdated - Sprint details modified
3. SprintStarted - Sprint transitioned to Active status
4. SprintCompleted - Sprint transitioned to Completed status
5. SprintDeleted - Sprint removed

Technical Details:
- Event handlers catch and log errors (fire-and-forget pattern)
- Notifications include SprintId, SprintName, ProjectId, and Timestamp
- Multi-tenant isolation via tenant groups
- Project-level targeting via project groups

Frontend Integration:
- Frontend can listen to 'SprintCreated', 'SprintUpdated', 'SprintStarted', 'SprintCompleted', 'SprintDeleted' events
- Real-time UI updates for sprint changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

colaflow-api/src/ColaFlow.API/EventHandlers/SprintEventHandlers.cs

@@ -0,0 +1,139 @@
+using MediatR;
+using ColaFlow.API.Services;
+using ColaFlow.Modules.ProjectManagement.Domain.Events;
+using Microsoft.Extensions.Logging;
+
+namespace ColaFlow.API.EventHandlers;
+
+/// <summary>
+/// Handles Sprint domain events and sends SignalR notifications
+/// </summary>
+public class SprintEventHandlers :
+    INotificationHandler<SprintCreatedEvent>,
+    INotificationHandler<SprintUpdatedEvent>,
+    INotificationHandler<SprintStartedEvent>,
+    INotificationHandler<SprintCompletedEvent>,
+    INotificationHandler<SprintDeletedEvent>
+{
+    private readonly IRealtimeNotificationService _notificationService;
+    private readonly ILogger<SprintEventHandlers> _logger;
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    public SprintEventHandlers(
+        IRealtimeNotificationService notificationService,
+        ILogger<SprintEventHandlers> logger,
+        IHttpContextAccessor httpContextAccessor)
+    {
+        _notificationService = notificationService ?? throw new ArgumentNullException(nameof(notificationService));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _httpContextAccessor = httpContextAccessor ?? throw new ArgumentNullException(nameof(httpContextAccessor));
+    }
+
+    public async Task Handle(SprintCreatedEvent notification, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var tenantId = GetCurrentTenantId();
+            await _notificationService.NotifySprintCreated(
+                tenantId,
+                notification.ProjectId,
+                notification.SprintId,
+                notification.SprintName
+            );
+            _logger.LogInformation("Sprint created notification sent: {SprintId}", notification.SprintId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send Sprint created notification: {SprintId}", notification.SprintId);
+        }
+    }
+
+    public async Task Handle(SprintUpdatedEvent notification, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var tenantId = GetCurrentTenantId();
+            await _notificationService.NotifySprintUpdated(
+                tenantId,
+                notification.ProjectId,
+                notification.SprintId,
+                notification.SprintName
+            );
+            _logger.LogInformation("Sprint updated notification sent: {SprintId}", notification.SprintId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send Sprint updated notification: {SprintId}", notification.SprintId);
+        }
+    }
+
+    public async Task Handle(SprintStartedEvent notification, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var tenantId = GetCurrentTenantId();
+            await _notificationService.NotifySprintStarted(
+                tenantId,
+                notification.ProjectId,
+                notification.SprintId,
+                notification.SprintName
+            );
+            _logger.LogInformation("Sprint started notification sent: {SprintId}", notification.SprintId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send Sprint started notification: {SprintId}", notification.SprintId);
+        }
+    }
+
+    public async Task Handle(SprintCompletedEvent notification, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var tenantId = GetCurrentTenantId();
+            await _notificationService.NotifySprintCompleted(
+                tenantId,
+                notification.ProjectId,
+                notification.SprintId,
+                notification.SprintName
+            );
+            _logger.LogInformation("Sprint completed notification sent: {SprintId}", notification.SprintId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send Sprint completed notification: {SprintId}", notification.SprintId);
+        }
+    }
+
+    public async Task Handle(SprintDeletedEvent notification, CancellationToken cancellationToken)
+    {
+        try
+        {
+            var tenantId = GetCurrentTenantId();
+            await _notificationService.NotifySprintDeleted(
+                tenantId,
+                notification.ProjectId,
+                notification.SprintId,
+                notification.SprintName
+            );
+            _logger.LogInformation("Sprint deleted notification sent: {SprintId}", notification.SprintId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to send Sprint deleted notification: {SprintId}", notification.SprintId);
+        }
+    }
+
+    private Guid GetCurrentTenantId()
+    {
+        var tenantIdClaim = _httpContextAccessor?.HttpContext?.User
+            .FindFirst("tenant_id")?.Value;
+
+        if (Guid.TryParse(tenantIdClaim, out var tenantId) && tenantId != Guid.Empty)
+        {
+            return tenantId;
+        }
+
+        return Guid.Empty; // Default for non-HTTP contexts
+    }
+}

colaflow-api/src/ColaFlow.API/Services/IRealtimeNotificationService.cs

@@ -30,6 +30,13 @@ public interface IRealtimeNotificationService
     Task NotifyIssueDeleted(Guid tenantId, Guid projectId, Guid issueId);
     Task NotifyIssueStatusChanged(Guid tenantId, Guid projectId, Guid issueId, string oldStatus, string newStatus);
 
+    // Sprint notifications
+    Task NotifySprintCreated(Guid tenantId, Guid projectId, Guid sprintId, string sprintName);
+    Task NotifySprintUpdated(Guid tenantId, Guid projectId, Guid sprintId, string sprintName);
+    Task NotifySprintStarted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName);
+    Task NotifySprintCompleted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName);
+    Task NotifySprintDeleted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName);
+
     // User-level notifications
     Task NotifyUser(Guid userId, string message, string type = "info");
     Task NotifyUsersInTenant(Guid tenantId, string message, string type = "info");

colaflow-api/src/ColaFlow.API/Services/RealtimeNotificationService.cs

@@ -202,6 +202,118 @@ public class RealtimeNotificationService : IRealtimeNotificationService
         });
     }
 
+    // Sprint notifications
+    public async Task NotifySprintCreated(Guid tenantId, Guid projectId, Guid sprintId, string sprintName)
+    {
+        var projectGroupName = $"project-{projectId}";
+        var tenantGroupName = $"tenant-{tenantId}";
+
+        _logger.LogInformation("Notifying sprint {SprintId} created in project {ProjectId}", sprintId, projectId);
+
+        await _projectHubContext.Clients.Group(projectGroupName).SendAsync("SprintCreated", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+
+        await _projectHubContext.Clients.Group(tenantGroupName).SendAsync("SprintCreated", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
+    public async Task NotifySprintUpdated(Guid tenantId, Guid projectId, Guid sprintId, string sprintName)
+    {
+        var projectGroupName = $"project-{projectId}";
+
+        _logger.LogInformation("Notifying sprint {SprintId} updated", sprintId);
+
+        await _projectHubContext.Clients.Group(projectGroupName).SendAsync("SprintUpdated", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
+    public async Task NotifySprintStarted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName)
+    {
+        var projectGroupName = $"project-{projectId}";
+        var tenantGroupName = $"tenant-{tenantId}";
+
+        _logger.LogInformation("Notifying sprint {SprintId} started", sprintId);
+
+        await _projectHubContext.Clients.Group(projectGroupName).SendAsync("SprintStarted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+
+        await _projectHubContext.Clients.Group(tenantGroupName).SendAsync("SprintStarted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
+    public async Task NotifySprintCompleted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName)
+    {
+        var projectGroupName = $"project-{projectId}";
+        var tenantGroupName = $"tenant-{tenantId}";
+
+        _logger.LogInformation("Notifying sprint {SprintId} completed", sprintId);
+
+        await _projectHubContext.Clients.Group(projectGroupName).SendAsync("SprintCompleted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+
+        await _projectHubContext.Clients.Group(tenantGroupName).SendAsync("SprintCompleted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
+    public async Task NotifySprintDeleted(Guid tenantId, Guid projectId, Guid sprintId, string sprintName)
+    {
+        var projectGroupName = $"project-{projectId}";
+        var tenantGroupName = $"tenant-{tenantId}";
+
+        _logger.LogInformation("Notifying sprint {SprintId} deleted", sprintId);
+
+        await _projectHubContext.Clients.Group(projectGroupName).SendAsync("SprintDeleted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+
+        await _projectHubContext.Clients.Group(tenantGroupName).SendAsync("SprintDeleted", new
+        {
+            SprintId = sprintId,
+            SprintName = sprintName,
+            ProjectId = projectId,
+            Timestamp = DateTime.UtcNow
+        });
+    }
+
     public async Task NotifyUser(Guid userId, string message, string type = "info")
     {
         var userConnectionId = $"user-{userId}";

colaflow-api/src/Modules/ProjectManagement/ColaFlow.Modules.ProjectManagement.Application/Commands/UpdateSprint/UpdateSprintCommandHandler.cs

@@ -4,6 +4,7 @@ using ColaFlow.Modules.ProjectManagement.Application.Common.Interfaces;
 using ColaFlow.Modules.ProjectManagement.Domain.Repositories;
 using ColaFlow.Modules.ProjectManagement.Domain.ValueObjects;
 using ColaFlow.Modules.ProjectManagement.Domain.Exceptions;
+using ColaFlow.Modules.ProjectManagement.Domain.Events;
 
 namespace ColaFlow.Modules.ProjectManagement.Application.Commands.UpdateSprint;
 
@@ -12,11 +13,13 @@ namespace ColaFlow.Modules.ProjectManagement.Application.Commands.UpdateSprint;
 /// </summary>
 public sealed class UpdateSprintCommandHandler(
     IApplicationDbContext context,
-    IUnitOfWork unitOfWork)
+    IUnitOfWork unitOfWork,
+    IMediator mediator)
     : IRequestHandler<UpdateSprintCommand, Unit>
 {
     private readonly IApplicationDbContext _context = context ?? throw new ArgumentNullException(nameof(context));
     private readonly IUnitOfWork _unitOfWork = unitOfWork ?? throw new ArgumentNullException(nameof(unitOfWork));
+    private readonly IMediator _mediator = mediator ?? throw new ArgumentNullException(nameof(mediator));
 
     public async Task<Unit> Handle(UpdateSprintCommand request, CancellationToken cancellationToken)
     {
@@ -39,6 +42,9 @@ public sealed class UpdateSprintCommandHandler(
         // Save changes
         await _unitOfWork.SaveChangesAsync(cancellationToken);
 
+        // Publish domain event
+        await _mediator.Publish(new SprintUpdatedEvent(sprint.Id.Value, sprint.Name, sprint.ProjectId.Value), cancellationToken);
+
         return Unit.Value;
     }
 }