diff --git a/src/XtremeIdiots.Portal.Server.Events.Processor.App.Tests/Startup/RepositoryApiClientRegistrationTests.cs b/src/XtremeIdiots.Portal.Server.Events.Processor.App.Tests/Startup/RepositoryApiClientRegistrationTests.cs
new file mode 100644
index 0000000..9a12e6e
--- /dev/null
+++ b/src/XtremeIdiots.Portal.Server.Events.Processor.App.Tests/Startup/RepositoryApiClientRegistrationTests.cs
@@ -0,0 +1,88 @@
+using Microsoft.Extensions.DependencyInjection;
+
+using XtremeIdiots.Portal.Repository.Abstractions.Interfaces.V1;
+using XtremeIdiots.Portal.Repository.Api.Client.V1;
+
+namespace XtremeIdiots.Portal.Server.Events.Processor.App.Tests.Startup;
+
+/// <summary>
+/// Startup-time DI resolution tests for the Repository API client registration used by the
+/// Processor App. These tests replicate the production registration in
+/// <c>Program.cs</c> and prove the container can build and resolve every typed sub-client
+/// the app depends on (e.g. <see cref="IAdminActionsApi"/>). They exercise real DI
+/// resolution rather than inspecting option flags so that any regression in the
+/// <c>services.AddRepositoryApiClient(...)</c> composition — such as the
+/// <c>WithCaching(c =&gt; c.UseLibraryDefaults())</c> policy expression rejection that
+/// crashed portal-sync / portal-repository-func on Repository 4.2.21 — is caught here
+/// before it reaches production.
+/// </summary>
+public class RepositoryApiClientRegistrationTests
+{
+    private const string BaseUrl = "https://repository-api.test.local";
+    private const string Audience = "api://repository-api-test";
+
+    [Fact]
+    public void ProductionRegistration_BuildsAndResolvesRepositoryClient()
+    {
+        var provider = BuildProductionServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var repositoryClient = scope.ServiceProvider.GetRequiredService<IRepositoryApiClient>();
+
+        Assert.NotNull(repositoryClient);
+    }
+
+    [Fact]
+    public void ProductionRegistration_ResolvesAdminActionsSubClient()
+    {
+        var provider = BuildProductionServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var repositoryClient = scope.ServiceProvider.GetRequiredService<IRepositoryApiClient>();
+        IAdminActionsApi adminActions = repositoryClient.AdminActions.V1;
+
+        Assert.NotNull(adminActions);
+        Assert.NotNull(scope.ServiceProvider.GetRequiredService<IVersionedAdminActionsApi>());
+    }
+
+    [Fact]
+    public void ProductionRegistration_ResolvesRepresentativeSubClients()
+    {
+        var provider = BuildProductionServiceProvider();
+        using var scope = provider.CreateScope();
+
+        var repositoryClient = scope.ServiceProvider.GetRequiredService<IRepositoryApiClient>();
+
+        // Every sub-client the processor actually calls at runtime must be resolvable.
+        // Touching .V1 on each versioned facade forces the DI graph for the underlying
+        // typed client to be materialised — which is where the client-side caching
+        // policy composition failure surfaces on start-up.
+        Assert.NotNull(repositoryClient.AdminActions.V1);
+        Assert.NotNull(repositoryClient.Players.V1);
+        Assert.NotNull(repositoryClient.GameServers.V1);
+        Assert.NotNull(repositoryClient.GameServersEvents.V1);
+        Assert.NotNull(repositoryClient.GameServersStats.V1);
+        Assert.NotNull(repositoryClient.ChatMessages.V1);
+        Assert.NotNull(repositoryClient.Maps.V1);
+        Assert.NotNull(repositoryClient.ConnectedPlayers.V1);
+        Assert.NotNull(repositoryClient.RecentPlayers.V1);
+        Assert.NotNull(repositoryClient.GlobalConfigurations.V1);
+        Assert.NotNull(repositoryClient.GameServerConfigurations.V1);
+        Assert.NotNull(repositoryClient.LiveStatus.V1);
+    }
+
+    private static ServiceProvider BuildProductionServiceProvider()
+    {
+        var services = new ServiceCollection();
+
+        // Mirror the Repository API client registration in
+        // src/XtremeIdiots.Portal.Server.Events.Processor.App/Program.cs.
+        // Any deviation here (in particular re-introducing consumer-side WithCaching)
+        // must also be applied to Program.cs.
+        services.AddRepositoryApiClient(options => options
+            .WithBaseUrl(BaseUrl)
+            .WithEntraIdAuthentication(Audience));
+
+        return services.BuildServiceProvider(validateScopes: true);
+    }
+}
diff --git a/src/XtremeIdiots.Portal.Server.Events.Processor.App/Program.cs b/src/XtremeIdiots.Portal.Server.Events.Processor.App/Program.cs
index 4bf84b6..aa243e6 100644
--- a/src/XtremeIdiots.Portal.Server.Events.Processor.App/Program.cs
+++ b/src/XtremeIdiots.Portal.Server.Events.Processor.App/Program.cs
@@ -92,8 +92,7 @@
 
         services.AddRepositoryApiClient(options => options
             .WithBaseUrl(configuration["RepositoryApi:BaseUrl"] ?? throw new InvalidOperationException("RepositoryApi:BaseUrl is required"))
-            .WithEntraIdAuthentication(configuration["RepositoryApi:ApplicationAudience"] ?? throw new InvalidOperationException("RepositoryApi:ApplicationAudience is required"))
-            .WithCaching(c => c.UseLibraryDefaults()));
+            .WithEntraIdAuthentication(configuration["RepositoryApi:ApplicationAudience"] ?? throw new InvalidOperationException("RepositoryApi:ApplicationAudience is required")));
 
         services.AddServersApiClient(options => options
             .WithBaseUrl(configuration["ServersIntegrationApi:BaseUrl"] ?? throw new InvalidOperationException("ServersIntegrationApi:BaseUrl is required"))