fix: Review-Fixes Sizing/Portfolio (invalid_stop-Guard, Doppel-Open-Schutz, Tests)

src/server/engine/portfolio.ts

@@ -41,13 +41,14 @@ export class Portfolio {
   }
 
   open(pair: Pair, ts: number, signalPrice: number, initialStop: number, qty: number, riskAmount: number): void {
+    if (this.positions.has(pair)) throw new Error(`open auf bestehende Position: ${pair}`);
     const fill = signalPrice * (1 + this.exec.slippage);
     const cost = qty * fill;
     const fee = cost * this.exec.feeRate;
     this.cash -= cost + fee;
     this.positions.set(pair, {
       pair, qty, entryTs: ts, entryPrice: fill, entryCost: cost + fee,
-      initialStop, stop: initialStop, highestHigh: signalPrice, riskAmount,
+      initialStop, stop: initialStop, highestHigh: signalPrice, riskAmount, // Markt-Preis, nicht Fill: der Chandelier trailt Markt-Hochs, Slippage ist Ausführungsartefakt
     });
   }