fix(build): add domain event handlers to satisfy Mediator source generator

The Mediator source generator (MSG0005) requires every INotification message
to have at least one registered handler. Added INotificationHandler<T>
implementations for all 6 Identity domain events. UserRegisteredHandler also
bridges to the integration event pipeline.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: iammukeshm

src/Modules/Identity/Modules.Identity/Events/PasswordChangedEventHandler.cs

@@ -0,0 +1,28 @@
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the PasswordChangedEvent domain event.
+/// </summary>
+public sealed class PasswordChangedHandler(
+    ILogger<PasswordChangedHandler> logger)
+    : INotificationHandler<PasswordChangedEvent>
+{
+    public ValueTask Handle(PasswordChangedEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "Password changed for user {UserId} (reset: {WasReset})",
+                notification.UserId,
+                notification.WasReset);
+        }
+
+        return ValueTask.CompletedTask;
+    }
+}

src/Modules/Identity/Modules.Identity/Events/SessionRevokedEventHandler.cs

@@ -0,0 +1,30 @@
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the SessionRevokedEvent domain event.
+/// </summary>
+public sealed class SessionRevokedHandler(
+    ILogger<SessionRevokedHandler> logger)
+    : INotificationHandler<SessionRevokedEvent>
+{
+    public ValueTask Handle(SessionRevokedEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "Session {SessionId} revoked for user {UserId} by {RevokedBy}: {Reason}",
+                notification.SessionId,
+                notification.UserId,
+                notification.RevokedBy,
+                notification.Reason);
+        }
+
+        return ValueTask.CompletedTask;
+    }
+}

src/Modules/Identity/Modules.Identity/Events/UserActivatedEventHandler.cs

@@ -0,0 +1,28 @@
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the UserActivatedEvent domain event.
+/// </summary>
+public sealed class UserActivatedHandler(
+    ILogger<UserActivatedHandler> logger)
+    : INotificationHandler<UserActivatedEvent>
+{
+    public ValueTask Handle(UserActivatedEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "User {UserId} activated by {ActivatedBy}",
+                notification.UserId,
+                notification.ActivatedBy);
+        }
+
+        return ValueTask.CompletedTask;
+    }
+}

src/Modules/Identity/Modules.Identity/Events/UserDeactivatedEventHandler.cs

@@ -0,0 +1,29 @@
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the UserDeactivatedEvent domain event.
+/// </summary>
+public sealed class UserDeactivatedHandler(
+    ILogger<UserDeactivatedHandler> logger)
+    : INotificationHandler<UserDeactivatedEvent>
+{
+    public ValueTask Handle(UserDeactivatedEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "User {UserId} deactivated by {DeactivatedBy}: {Reason}",
+                notification.UserId,
+                notification.DeactivatedBy,
+                notification.Reason);
+        }
+
+        return ValueTask.CompletedTask;
+    }
+}

src/Modules/Identity/Modules.Identity/Events/UserRegisteredEventHandler.cs

@@ -0,0 +1,43 @@
+using FSH.Framework.Eventing.Abstractions;
+using FSH.Modules.Identity.Contracts.Events;
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the UserRegisteredEvent domain event by publishing an integration event
+/// so other modules can react to new user registrations.
+/// </summary>
+public sealed class UserRegisteredHandler(
+    IEventBus eventBus,
+    ILogger<UserRegisteredHandler> logger)
+    : INotificationHandler<UserRegisteredEvent>
+{
+    public async ValueTask Handle(UserRegisteredEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "User registered: {UserId} ({Email})",
+                notification.UserId,
+                notification.Email);
+        }
+
+        var integrationEvent = new UserRegisteredIntegrationEvent(
+            Id: notification.EventId,
+            OccurredOnUtc: notification.OccurredOnUtc.UtcDateTime,
+            TenantId: notification.TenantId,
+            CorrelationId: notification.CorrelationId ?? notification.EventId.ToString(),
+            Source: nameof(UserRegisteredHandler),
+            UserId: notification.UserId,
+            Email: notification.Email,
+            FirstName: notification.FirstName ?? string.Empty,
+            LastName: notification.LastName ?? string.Empty);
+
+        await eventBus.PublishAsync(integrationEvent, cancellationToken).ConfigureAwait(false);
+    }
+}

src/Modules/Identity/Modules.Identity/Events/UserRoleAssignedEventHandler.cs

@@ -0,0 +1,28 @@
+using FSH.Modules.Identity.Domain.Events;
+using Mediator;
+using Microsoft.Extensions.Logging;
+
+namespace FSH.Modules.Identity.Events;
+
+/// <summary>
+/// Handles the UserRoleAssignedEvent domain event.
+/// </summary>
+public sealed class UserRoleAssignedHandler(
+    ILogger<UserRoleAssignedHandler> logger)
+    : INotificationHandler<UserRoleAssignedEvent>
+{
+    public ValueTask Handle(UserRoleAssignedEvent notification, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(notification);
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "Roles assigned to user {UserId}: {Roles}",
+                notification.UserId,
+                string.Join(", ", notification.AssignedRoles));
+        }
+
+        return ValueTask.CompletedTask;
+    }
+}