Replace AsyncInitWorker with ConsumerInitWorker

Replaced the `AsyncInitWorker` background service with the new `ConsumerInitWorker`, which introduces enhanced error handling, logging, and configurability for RabbitMQ consumer initialization.

Updated `MessagingServiceDbContext` to remove the `UseCollation` configuration for the `Username` property in the `EmailAccount` entity, ensuring compatibility with the InMemory database.

Added the `ContinueOnInitFailure` property to `RabbitMqConfiguration` to allow the application to continue running if RabbitMQ consumer initialization fails.

Cleaned up unused `using` directives in `DependencyInjection.cs` and removed the obsolete `AsyncInitWorker` class.

src/infrastructure/DigitalData.MessagingService.Infrastructure/DependencyInjection.cs

@@ -1,4 +1,3 @@
-using AutoMapper;
 using DigitalData.MessagingService.Application.Common.Interfaces;
 using DigitalData.MessagingService.Application.Common.Interfaces.Repositories;
 using DigitalData.MessagingService.Infrastructure.Mappings;
@@ -9,7 +8,6 @@ using DigitalData.MessagingService.Infrastructure.Services;
 using DigitalData.MessagingService.Infrastructure.Services.Background;
 using DigitalData.MessagingService.Publisher;
 using DigitalData.MessagingService.RabbitMQ;
-using Microsoft.AspNetCore.DataProtection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -61,7 +59,7 @@ public static class DependencyInjection
         services.AddRabbitMqConnectionFactory(configuration);
 
         // Register Background Workers
-        services.AddHostedService<AsyncInitWorker>();
+        services.AddHostedService<ConsumerInitWorker>();
         services.AddHostedService<EmailSyncWorker>();
 
         services.AddSingleton<IEmailSyncService>(p =>

src/infrastructure/DigitalData.MessagingService.Infrastructure/Persistence/MessagingServiceDbContext.cs

@@ -18,8 +18,9 @@ public class MessagingServiceDbContext(DbContextOptions<MessagingServiceDbContex
 
         modelBuilder.Entity<EmailAccount>(entity =>
         {
-            entity.Property(e => e.Username)
-                  .UseCollation("SQL_Latin1_General_CP1_CI_AS");
+            // UseCollation is only supported by relational databases (e.g. SQL Server).
+            // Skipped here to remain compatible with the current InMemory database configuration.
+            // entity.Property(e => e.Username).UseCollation("SQL_Latin1_General_CP1_CI_AS");
         });
 
         modelBuilder.Entity<ReceivedEmail>(entity =>

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/Background/AsyncInitWorker.cs

@@ -1,19 +0,0 @@
-using DigitalData.MessagingService.Infrastructure.Queue;
-using Microsoft.Extensions.Hosting;
-
-namespace DigitalData.MessagingService.Infrastructure.Services.Background;
-
-/// <summary>
-/// A hosted background service responsible for initializing the competing email consumer pool.
-/// Leverages a push-based, event-driven RabbitMQ consumer to eliminate polling overhead.
-/// Email account configuration is resolved exclusively from application settings; no database access is performed.
-/// </summary>
-public class AsyncInitWorker(SendingEmailConsumerPool ConsumerPool) : BackgroundService
-{
-    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
-    {
-        await ConsumerPool.InitAsync();
-
-        await Task.Delay(Timeout.Infinite, stoppingToken).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
-    }
-}

src/infrastructure/DigitalData.MessagingService.Infrastructure/Services/Background/ConsumerInitWorker.cs

@@ -0,0 +1,34 @@
+using DigitalData.MessagingService.Infrastructure.Queue;
+using DigitalData.MessagingService.RabbitMQ;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace DigitalData.MessagingService.Infrastructure.Services.Background;
+
+/// <summary>
+/// A hosted background service responsible for initializing the competing email consumer pool.
+/// Leverages a push-based, event-driven RabbitMQ consumer to eliminate polling overhead.
+/// Email account configuration is resolved exclusively from application settings; no database access is performed.
+/// </summary>
+public class ConsumerInitWorker(SendingEmailConsumerPool ConsumerPool, ILogger<ConsumerInitWorker> Logger, IOptions<RabbitMqConfiguration> RabbitMqOptions) : BackgroundService
+{
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        try
+        {
+            await ConsumerPool.InitAsync();
+        }
+        catch (Exception ex)
+        {
+            // Log and continue — a RabbitMQ connection failure must not bring down the entire host.
+            // The API remains operational; only outgoing email delivery via the consumer pool is affected.
+            Logger.LogError(ex, "Failed to initialize SendingEmailConsumerPool. Outgoing email consumers are not running.");
+
+            if (!RabbitMqOptions.Value.ContinueOnInitFailure)
+                throw;
+        }
+
+        await Task.Delay(Timeout.Infinite, stoppingToken).ConfigureAwait(ConfigureAwaitOptions.SuppressThrowing);
+    }
+}

src/infrastructure/DigitalData.MessagingService.RabbitMQ/RabbitMqConfiguration.cs

@@ -81,5 +81,7 @@ namespace DigitalData.MessagingService.RabbitMQ
         /// Maps directly to RabbitMQ prefetchCount. Recommended: 3–5.
         /// </summary>
         public ushort ConsumerConcurrency { get; set; } = 5;
+
+        public bool ContinueOnInitFailure { get; set; } = false;
     }
 }