diff --git a/PolyTrader.App.csproj b/PolyTrader.App.csproj
index 439d0f5..07a34b8 100644
--- a/PolyTrader.App.csproj
+++ b/PolyTrader.App.csproj
@@ -28,6 +28,12 @@
     <Content Include="favicon.ico" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="appsettings.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
   <ItemGroup>
     <Folder Include="agentspace\antigravity\" />
   </ItemGroup>
diff --git a/Program.cs b/Program.cs
index f973a59..e61a02e 100644
--- a/Program.cs
+++ b/Program.cs
@@ -6,6 +6,8 @@ using System.Threading.Channels;
 using System.Windows.Forms;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
+using PolyTrader.Core.Configuration;
 using PolyTraderSharp.Models;
 using PolyTraderSharp.Services;
 
@@ -20,18 +22,17 @@ internal static class Program
 	{
 		ApplicationConfiguration.Initialize();
 
-        try 
-        {
-            var cleanupClient = new MongoClient("mongodb://localhost:27017");
-            var cleanupCol = cleanupClient.GetDatabase("PolyTraderDB").GetCollection<MongoDB.Bson.BsonDocument>("closed_trades");
-            cleanupCol.DeleteMany(Builders<MongoDB.Bson.BsonDocument>.Filter.Type("_id", MongoDB.Bson.BsonType.ObjectId));
-        }
-        catch { }
 		Channel<CopySignal> copySignalChannel = Channel.CreateUnbounded<CopySignal>();
 			Channel<ClosedTrade> closedTradeChannel = Channel.CreateUnbounded<ClosedTrade>();
 			AppHost = Host.CreateDefaultBuilder().ConfigureServices(delegate(HostBuilderContext context, IServiceCollection services)
 			{
-				services.AddSingleton((Func<IServiceProvider, IMongoDatabase>)((IServiceProvider sp) => { var client = new MongoClient("mongodb://localhost:27017"); return client.GetDatabase("PolyTraderDB"); }));
+				services.Configure<DatabaseOptions>(context.Configuration.GetSection(DatabaseOptions.SectionName));
+				services.AddSingleton<IMongoDatabase>((IServiceProvider sp) =>
+				{
+					var dbOptions = sp.GetRequiredService<IOptions<DatabaseOptions>>().Value;
+					var client = new MongoClient(dbOptions.ConnectionString);
+					return client.GetDatabase(dbOptions.DatabaseName);
+				});
 				services.AddSingleton((IServiceProvider sp) => ServerSettings.Load("server_settings.xml"));
 				services.AddSingleton<TradingState>();
 				services.AddSingleton(copySignalChannel.Writer);
@@ -85,6 +86,17 @@ internal static class Program
             try 
             {
                 var db = AppHost.Services.GetRequiredService<IMongoDatabase>();
+
+                // Einmal-Bereinigung (Alt-Bug): entferne closed_trades mit ObjectId-_id.
+                // Das _id muss die int-TradeId sein; fehlerhafte Auto-ObjectIds werden verworfen.
+                // Läuft jetzt über die konfigurierte DB statt über einen hart codierten Client.
+                try
+                {
+                    var cleanupCol = db.GetCollection<MongoDB.Bson.BsonDocument>("closed_trades");
+                    cleanupCol.DeleteMany(Builders<MongoDB.Bson.BsonDocument>.Filter.Type("_id", MongoDB.Bson.BsonType.ObjectId));
+                }
+                catch { }
+
                 var state = AppHost.Services.GetRequiredService<TradingState>();
                 var maxTradeDoc = db.GetCollection<MongoDB.Bson.BsonDocument>("closed_trades")
                     .Find(Builders<MongoDB.Bson.BsonDocument>.Filter.Empty)
diff --git a/appsettings.json b/appsettings.json
new file mode 100644
index 0000000..082f9e4
--- /dev/null
+++ b/appsettings.json
@@ -0,0 +1,6 @@
+{
+  "Database": {
+    "ConnectionString": "mongodb://localhost:27017",
+    "DatabaseName": "PolyTraderDB"
+  }
+}
diff --git a/src/PolyTrader.Core/Configuration/DatabaseOptions.cs b/src/PolyTrader.Core/Configuration/DatabaseOptions.cs
new file mode 100644
index 0000000..5bb754f
--- /dev/null
+++ b/src/PolyTrader.Core/Configuration/DatabaseOptions.cs
@@ -0,0 +1,15 @@
+namespace PolyTrader.Core.Configuration
+{
+    /// <summary>
+    /// Datenbank-Konfiguration, gebunden an die "Database"-Sektion in appsettings.json.
+    /// Ersetzt die frühere Hartcodierung von Connection-String und DB-Name.
+    /// </summary>
+    public class DatabaseOptions
+    {
+        public const string SectionName = "Database";
+
+        public string ConnectionString { get; set; } = "mongodb://localhost:27017";
+
+        public string DatabaseName { get; set; } = "PolyTraderDB";
+    }
+}