feat(notification-outbox): add AddNotificationOutbox DI registration

src/ScadaLink.NotificationOutbox/ServiceCollectionExtensions.cs

@@ -0,0 +1,49 @@
+using Microsoft.Extensions.DependencyInjection;
+using ScadaLink.NotificationOutbox.Delivery;
+
+namespace ScadaLink.NotificationOutbox;
+
+/// <summary>
+/// DI registration for the Notification Outbox component: binds
+/// <see cref="NotificationOutboxOptions"/> and registers the channel delivery adapters.
+/// </summary>
+public static class ServiceCollectionExtensions
+{
+    /// <summary>Configuration section bound to <see cref="NotificationOutboxOptions"/>.</summary>
+    public const string OptionsSection = "ScadaLink:NotificationOutbox";
+
+    /// <summary>
+    /// Registers the Notification Outbox services: the <see cref="NotificationOutboxOptions"/>
+    /// binding and the channel delivery adapters.
+    ///
+    /// This extension covers only the outbox-specific registrations. The
+    /// <see cref="EmailNotificationDeliveryAdapter"/> reuses the
+    /// <see cref="ScadaLink.NotificationService"/> SMTP machinery —
+    /// <c>Func&lt;ISmtpClientWrapper&gt;</c>, <c>OAuth2TokenService</c> and
+    /// <c>NotificationOptions</c> — so the caller (the Host on the central node) must also
+    /// call <c>AddNotificationService()</c>. Re-registering those services here would
+    /// duplicate them; relying on <c>AddNotificationService</c> keeps a single source of truth.
+    ///
+    /// <see cref="EmailNotificationDeliveryAdapter"/> is registered <em>scoped</em> because it
+    /// takes a scoped <see cref="ScadaLink.Commons.Interfaces.Repositories.INotificationRepository"/>
+    /// directly. The <see cref="NotificationOutboxActor"/> resolves the adapters from a fresh
+    /// scope per dispatch sweep rather than holding them, so no scoped adapter is captured by
+    /// the singleton actor.
+    /// </summary>
+    public static IServiceCollection AddNotificationOutbox(this IServiceCollection services)
+    {
+        ArgumentNullException.ThrowIfNull(services);
+
+        services.AddOptions<NotificationOutboxOptions>()
+            .BindConfiguration(OptionsSection);
+
+        // Scoped: the adapter holds a scoped INotificationRepository. Registered both under
+        // the interface (so the dispatch sweep can enumerate every channel adapter) and as
+        // the concrete type (so callers and tests can resolve it directly).
+        services.AddScoped<EmailNotificationDeliveryAdapter>();
+        services.AddScoped<INotificationDeliveryAdapter>(
+            sp => sp.GetRequiredService<EmailNotificationDeliveryAdapter>());
+
+        return services;
+    }
+}