diff --git a/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/Program.cs b/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/Program.cs
index 85c40e23..be078b8c 100644
--- a/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/Program.cs
+++ b/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/Program.cs
@@ -1,4 +1,8 @@
-using EnvelopeGenerator.ReceiverUI.Components;
+using EnvelopeGenerator.ReceiverUI.Client.Auth;
+using EnvelopeGenerator.ReceiverUI.Client.Services;
+using EnvelopeGenerator.ReceiverUI.Client.State;
+using EnvelopeGenerator.ReceiverUI.Components;
+using Microsoft.AspNetCore.Components.Authorization;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -14,6 +18,32 @@ var apiBaseUrl = builder.Configuration["ApiBaseUrl"]
 
 builder.Services.AddHttpForwarder();
 
+// ── Services: Müssen AUCH auf dem Server registriert sein ──
+// WARUM? Bei @rendermode InteractiveAuto rendert Blazor die Seite zuerst
+// auf dem Server (SSR/Prerendering). Dabei resolved es @inject-Properties.
+// Wenn ein Service nur im Client-Projekt (WASM) registriert ist, aber nicht
+// hier, gibt es eine InvalidOperationException beim Prerendering.
+//
+// Der HttpClient auf dem Server zeigt auf sich selbst (localhost),
+// weil die /api/* Requests über MapForwarder an die echte API gehen.
+builder.Services.AddScoped(sp =>
+{
+    var navigationManager = sp.GetService<Microsoft.AspNetCore.Components.NavigationManager>();
+    var baseUri = navigationManager?.BaseUri ?? $"https://localhost:{builder.Configuration["ASPNETCORE_HTTPS_PORT"] ?? "7206"}/";
+    return new HttpClient { BaseAddress = new Uri(baseUri) };
+});
+
+builder.Services.AddAuthorizationCore();
+builder.Services.AddScoped<ApiAuthStateProvider>();
+builder.Services.AddScoped<AuthenticationStateProvider>(sp =>
+    sp.GetRequiredService<ApiAuthStateProvider>());
+
+builder.Services.AddScoped<IAuthService, AuthService>();
+builder.Services.AddScoped<IEnvelopeService, EnvelopeService>();
+builder.Services.AddScoped<IReceiverAuthService, ReceiverAuthService>();
+builder.Services.AddScoped<EnvelopeState>();
+builder.Services.AddScoped<ToastService>();
+
 var app = builder.Build();
 
 if (app.Environment.IsDevelopment())
diff --git a/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/appsettings.json b/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/appsettings.json
index bbee3a49..b4f03b2f 100644
--- a/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/appsettings.json
+++ b/EnvelopeGenerator.ReceiverUI/EnvelopeGenerator.ReceiverUI/appsettings.json
@@ -1,5 +1,5 @@
 {
-  "ApiBaseUrl": "https://localhost:5001",
+  "ApiBaseUrl": "https://localhost:8088",
   "Logging": {
     "LogLevel": {
       "Default": "Information",