@

Phase 3: Trading-Kern (Risk, Execution, Portfolio) mit sicherem Broker-Default

- Core/Trading/TradingModels: Signal, Order(Request/Result), RiskContext/Decision,
  Account, Position, Quote, ExecutionResult, Enums (Side/OrderType/Mode)
- IBrokerClient + NullBrokerClient (sicherer Default, handelt NIE bis IBKR-Adapter verifiziert)
- RiskService (+IRiskService): Sizing nach MaxTrade%, Modul-Limit, Slippage; Buy/Sell
- PortfolioService (+IPortfolioService): core_position + core_trade_history + core_budget
- ExecutionService (+IExecutionService): Signal -> Kurs -> Konto -> Risiko -> Order -> Buchung
- TradingSettings in AppSettings (Paper/Live, TradingEnabled, Risikoparameter)
- CoreMigrations: core_position; DI-Registrierung der Trading-Services
- Tests: RiskService (11) + ExecutionService (6, NSubstitute) -> 38/38 gruen

Offen (bewusst gekapselt): echter IbkrBrokerClient gegen Client-Portal-Gateway (manuell verifizieren).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
@

Core/Trading/NullBrokerClient.cs

@@ -0,0 +1,29 @@
+using IBKRTrader.Core.Logging;
+
+namespace IBKRTrader.Core.Trading;
+
+/// <summary>
+/// Sicherer Standard-Broker: handelt NIEMALS.
+/// Wird registriert, bis der echte IBKR-Adapter angebunden und gegen den
+/// Paper-Gateway verifiziert ist. So kann keine Order versehentlich rausgehen.
+/// </summary>
+public sealed class NullBrokerClient : IBrokerClient
+{
+    private readonly LoggingService _logger;
+
+    public NullBrokerClient(LoggingService logger) => _logger = logger;
+
+    public Task<Quote?> GetQuoteAsync(string symbol, CancellationToken ct = default)
+        => Task.FromResult<Quote?>(null);
+
+    public Task<AccountState> GetAccountStateAsync(CancellationToken ct = default)
+        => Task.FromResult(new AccountState(0m, 0m));
+
+    public Task<OrderResult> PlaceOrderAsync(OrderRequest request, CancellationToken ct = default)
+    {
+        _logger.Warn("Core",
+            $"NullBrokerClient: Order NICHT ausgeführt ({request.Side} {request.Quantity}x {request.Symbol}) " +
+            "– echter IBKR-Broker noch nicht angebunden.");
+        return Task.FromResult(OrderResult.Fail("Broker nicht angebunden (NullBrokerClient)."));
+    }
+}