Fix high-severity issues identified by Codex

1. Paper equity calculation (High):
   - get_balance() now correctly includes position value (size * current_price)
   - Previously only added unrealized_pnl, missing position principal

2. Buy affordability checks (High):
   - place_order() now uses execution price including slippage for market orders
   - Uses limit price for limit orders instead of current price
   - Prevents orders that would drive cash negative

3. ExchangeInterface price stubs (High):
   - get_trade_executed_price() now handles order_price=0.0 (market orders)
   - Falls back to current price or entry price when order_price is zero

4. Determinism hash strengthening (Medium):
   - Hash now includes full trade sequence with individual trade details
   - Added test for different trade sequences with same totals

5. Live mode consistency (Medium):
   - Factory now falls back to paper trading with warning instead of raising
   - Consistent behavior between factory.py and Strategies.py

Added test: test_paper_broker_equity_calculation to verify fix #1

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/ExchangeInterface.py

@@ -352,14 +352,25 @@ class ExchangeInterface:
         """
         Get the executed price of a trade order.
 
-        For paper/backtest modes, returns the order price.
+        For paper/backtest modes, returns the order price or current market price.
 
         :param trade: The trade object.
         :return: Executed price.
         """
-        # For paper trading / backtesting, use order price
+        # For paper trading / backtesting, use order price if set
+        if trade.order_price and trade.order_price > 0:
             return trade.order_price
 
+        # For market orders (order_price=0), get current price
+        try:
+            return self.get_price(trade.symbol)
+        except Exception:
+            # Fallback: if we can't get price, return entry price if available
+            if hasattr(trade, 'entry_price') and trade.entry_price > 0:
+                return trade.entry_price
+            # Last resort: return 0 and let caller handle it
+            return 0.0
+
     def get_user_balance(self, user_id: int) -> float:
         """
         Get the balance for a user.

src/backtest_result.py

@@ -117,21 +117,36 @@ class BacktestResult:
         Generate a hash of the deterministic parts of the result.
 
         Excludes non-deterministic fields like run_datetime and run_duration.
+        Includes full trade sequence to detect different trade distributions.
         """
         import hashlib
 
-        # Include only deterministic fields
+        # Normalize trade data for comparison (include sequence information)
+        normalized_trades = []
+        for i, t in enumerate(self.trades):
+            normalized_trades.append({
+                'seq': i,  # Preserve order
+                'pnl': round(t.get('pnl', 0), 6),
+                'pnlcomm': round(t.get('pnlcomm', t.get('pnl', 0)), 6),
+                'size': round(t.get('size', 0), 6),
+                'open_price': round(t.get('open_price', 0), 6),
+                'close_price': round(t.get('close_price', 0), 6) if t.get('close_price') else None,
+            })
+
+        # Include only deterministic fields with full trade sequence
         deterministic_data = {
             'strategy_id': self.strategy_id,
             'initial_capital': self.initial_capital,
             'final_portfolio_value': round(self.final_portfolio_value, 6),
             'equity_curve': [round(e, 6) for e in self.equity_curve],
-            'trades_count': len(self.trades),
+            'trades': normalized_trades,  # Full trade sequence
-            'trades_pnl': sum(t.get('pnl', 0) for t in self.trades),
             'metrics': {
                 'total_return': round(self.metrics.total_return, 6),
                 'number_of_trades': self.metrics.number_of_trades,
+                'sharpe_ratio': round(self.metrics.sharpe_ratio, 6),
+                'max_drawdown': round(self.metrics.max_drawdown, 6),
                 'win_rate': round(self.metrics.win_rate, 6),
+                'profit_factor': round(self.metrics.profit_factor, 6),
             }
         }
 

src/brokers/factory.py

@@ -71,10 +71,18 @@ def create_broker(
         )
 
     elif mode == TradingMode.LIVE:
-        # Live broker will be implemented in Phase 5
+        # Live broker not yet implemented - fall back to paper trading with warning
-        raise NotImplementedError(
+        logger.warning(
             "Live trading broker not yet implemented. "
-            "Use paper trading for testing with live prices."
+            "Falling back to paper trading for safety."
+        )
+        return PaperBroker(
+            initial_balance=initial_balance,
+            commission=commission,
+            slippage=slippage if slippage > 0 else 0.0005,
+            price_provider=price_provider,
+            data_cache=data_cache,
+            **kwargs
         )
 
     else:

src/brokers/paper_broker.py

@@ -144,8 +144,18 @@ class PaperBroker(BaseBroker):
                 message=f"Cannot get current price for {symbol}"
             )
 
-        # Calculate required margin/cost
+        # Calculate required margin/cost using the actual execution price
-        order_value = size * current_price
+        # For market orders: include slippage; for limit orders: use limit price
+        if order_type == OrderType.MARKET:
+            if side == OrderSide.BUY:
+                execution_price = current_price * (1 + self.slippage)
+            else:
+                execution_price = current_price * (1 - self.slippage)
+        else:
+            # For limit orders, use the limit price (or current price if not specified)
+            execution_price = price if price else current_price
+
+        order_value = size * execution_price
         required_funds = order_value * (1 + self.commission)
 
         if side == OrderSide.BUY and required_funds > self._cash:
@@ -306,10 +316,11 @@ class PaperBroker(BaseBroker):
         return open_orders
 
     def get_balance(self, asset: Optional[str] = None) -> float:
-        """Get total balance including unrealized P&L."""
+        """Get total equity (cash + locked + position values)."""
         total = self._cash + self._locked_balance
         for position in self._positions.values():
-            total += position.unrealized_pnl
+            # Include full position value (size * current_price), not just unrealized PnL
+            total += position.size * position.current_price
         return total
 
     def get_available_balance(self, asset: Optional[str] = None) -> float:

tests/test_backtest_determinism.py

@@ -120,6 +120,20 @@ class TestBacktestDeterminism:
 
     def test_same_inputs_same_hash(self):
         """Test that identical inputs produce the same hash."""
+        # Use identical trade data with all required fields
+        trades = [
+            {'ref': 1, 'pnl': 500, 'pnlcomm': 499, 'size': 0.1, 'open_price': 50000, 'close_price': 55000, 'side': 'buy'},
+            {'ref': 2, 'pnl': 500, 'pnlcomm': 499, 'size': 0.1, 'open_price': 55000, 'close_price': 60000, 'side': 'sell'},
+        ]
+        stats = {
+            'total_return': 10.0,
+            'number_of_trades': 2,
+            'win_rate': 100.0,
+            'sharpe_ratio': 1.5,
+            'max_drawdown': -2.0,
+            'profit_factor': 2.0,
+        }
+
         result1 = create_backtest_result(
             strategy_id='strategy-abc',
             strategy_name='Test Strategy',
@@ -128,15 +142,8 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=11000.0,
             equity_curve=[10000, 10500, 11000],
-            trades=[
+            trades=trades,
-                {'ref': 1, 'pnl': 500, 'side': 'buy'},
+            stats=stats,
-                {'ref': 2, 'pnl': 500, 'side': 'sell'},
-            ],
-            stats={
-                'total_return': 10.0,
-                'number_of_trades': 2,
-                'win_rate': 100.0,
-            },
             run_duration=1.0,
         )
 
@@ -148,15 +155,8 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=11000.0,
             equity_curve=[10000, 10500, 11000],
-            trades=[
+            trades=trades,  # Same trades
-                {'ref': 1, 'pnl': 500, 'side': 'buy'},
+            stats=stats,  # Same stats
-                {'ref': 2, 'pnl': 500, 'side': 'sell'},
-            ],
-            stats={
-                'total_return': 10.0,
-                'number_of_trades': 2,
-                'win_rate': 100.0,
-            },
             run_duration=2.0,  # Different runtime
         )
 
@@ -173,7 +173,7 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=11000.0,
             equity_curve=[10000, 10500, 11000],
-            trades=[{'pnl': 1000}],
+            trades=[{'pnl': 1000, 'size': 0.1, 'open_price': 50000, 'close_price': 60000}],
             stats={'total_return': 10.0, 'win_rate': 100.0, 'number_of_trades': 1},
             run_duration=1.0,
         )
@@ -186,15 +186,55 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=10500.0,  # Different final value
             equity_curve=[10000, 10250, 10500],  # Different curve
-            trades=[{'pnl': 500}],  # Different PnL
+            trades=[{'pnl': 500, 'size': 0.1, 'open_price': 50000, 'close_price': 55000}],  # Different
             stats={'total_return': 5.0, 'win_rate': 100.0, 'number_of_trades': 1},
             run_duration=1.0,
         )
 
         assert result1.get_determinism_hash() != result2.get_determinism_hash()
 
+    def test_different_trade_sequence_different_hash(self):
+        """Test that different trade sequences produce different hashes even with same totals."""
+        # Two trades: +500, +500 = same total as +200, +800
+        result1 = create_backtest_result(
+            strategy_id='strategy-abc',
+            strategy_name='Test',
+            user_id=1,
+            backtest_id='bt-001',
+            initial_capital=10000.0,
+            final_value=11000.0,
+            equity_curve=[10000, 10500, 11000],
+            trades=[
+                {'pnl': 500, 'size': 0.1, 'open_price': 50000, 'close_price': 55000},
+                {'pnl': 500, 'size': 0.1, 'open_price': 55000, 'close_price': 60000},
+            ],
+            stats={'total_return': 10.0, 'win_rate': 100.0, 'number_of_trades': 2},
+            run_duration=1.0,
+        )
+
+        result2 = create_backtest_result(
+            strategy_id='strategy-abc',
+            strategy_name='Test',
+            user_id=1,
+            backtest_id='bt-001',
+            initial_capital=10000.0,
+            final_value=11000.0,  # Same final value
+            equity_curve=[10000, 10200, 11000],  # Different curve
+            trades=[
+                {'pnl': 200, 'size': 0.1, 'open_price': 50000, 'close_price': 52000},  # Different
+                {'pnl': 800, 'size': 0.1, 'open_price': 52000, 'close_price': 60000},  # Different
+            ],
+            stats={'total_return': 10.0, 'win_rate': 100.0, 'number_of_trades': 2},  # Same totals
+            run_duration=1.0,
+        )
+
+        # Should be different even though total PnL is the same
+        assert result1.get_determinism_hash() != result2.get_determinism_hash()
+
     def test_verify_determinism(self):
         """Test the verify_determinism method."""
+        stats = {'total_return': 5.0, 'number_of_trades': 0, 'win_rate': 0.0, 'sharpe_ratio': 0.0, 'max_drawdown': 0.0, 'profit_factor': 0.0}
+
         result1 = create_backtest_result(
             strategy_id='strategy-1',
             strategy_name='Test',
@@ -204,7 +244,7 @@ class TestBacktestDeterminism:
             final_value=10500,
             equity_curve=[10000, 10250, 10500],
             trades=[],
-            stats={'total_return': 5.0, 'number_of_trades': 0, 'win_rate': 0.0},
+            stats=stats,
             run_duration=1.0,
         )
 
@@ -218,7 +258,7 @@ class TestBacktestDeterminism:
             final_value=10500,
             equity_curve=[10000, 10250, 10500],
             trades=[],
-            stats={'total_return': 5.0, 'number_of_trades': 0, 'win_rate': 0.0},
+            stats=stats,
             run_duration=2.0,
         )
 
@@ -226,7 +266,9 @@ class TestBacktestDeterminism:
 
     def test_floating_point_precision(self):
         """Test that floating point precision doesn't break determinism."""
-        # Results with slightly different floating point representations
+        trades = [{'pnl': 500.123456, 'size': 0.123456, 'open_price': 50000.123, 'close_price': 55000.456}]
+        stats = {'total_return': 5.001234, 'number_of_trades': 1, 'win_rate': 100.0, 'sharpe_ratio': 1.234, 'max_drawdown': -0.5, 'profit_factor': 2.5}
+
         result1 = create_backtest_result(
             strategy_id='strategy-1',
             strategy_name='Test',
@@ -235,8 +277,8 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=10500.123456,
             equity_curve=[10000.0, 10500.123456],
-            trades=[{'pnl': 500.123456}],
+            trades=trades,
-            stats={'total_return': 5.001234, 'number_of_trades': 1, 'win_rate': 100.0},
+            stats=stats,
             run_duration=1.0,
         )
 
@@ -248,8 +290,8 @@ class TestBacktestDeterminism:
             initial_capital=10000.0,
             final_value=10500.123456,
             equity_curve=[10000.0, 10500.123456],
-            trades=[{'pnl': 500.123456}],
+            trades=trades,
-            stats={'total_return': 5.001234, 'number_of_trades': 1, 'win_rate': 100.0},
+            stats=stats,
             run_duration=1.0,
         )
 

tests/test_brokers.py

@@ -164,6 +164,36 @@ class TestPaperBroker:
         # Unrealized P&L: (52000 - 50000) * 0.1 = 200
         assert position.unrealized_pnl == 200
 
+    def test_paper_broker_equity_calculation(self):
+        """Test that equity = cash + position value (not just unrealized PnL)."""
+        broker = PaperBroker(initial_balance=10000, commission=0, slippage=0)
+        broker.update_price('BTC/USDT', 100)
+
+        # Initial equity should equal initial balance
+        assert broker.get_balance() == 10000
+
+        # Buy 1 unit at $100 = spend $100
+        broker.place_order(
+            symbol='BTC/USDT',
+            side=OrderSide.BUY,
+            order_type=OrderType.MARKET,
+            size=1.0
+        )
+
+        # Cash is now 9900, position value is 100
+        # Total equity should still be 10000 (9900 + 100)
+        assert broker.get_available_balance() == 9900  # Cash
+        assert broker.get_balance() == 10000  # Total equity
+
+        # Price doubles
+        broker.update_price('BTC/USDT', 200)
+        broker.update()
+
+        # Cash still 9900, position value now 200
+        # Total equity should be 10100 (9900 + 200)
+        assert broker.get_available_balance() == 9900
+        assert broker.get_balance() == 10100
+
     def test_paper_broker_reset(self):
         """Test broker reset."""
         broker = PaperBroker(initial_balance=10000)
@@ -202,10 +232,12 @@ class TestBrokerFactory:
         )
         assert isinstance(broker, BacktestBroker)
 
-    def test_create_live_broker_not_implemented(self):
+    def test_create_live_broker_falls_back_to_paper(self):
-        """Test that live broker raises NotImplementedError."""
+        """Test that live broker falls back to paper broker with warning."""
-        with pytest.raises(NotImplementedError):
+        broker = create_broker(mode=TradingMode.LIVE, initial_balance=5000)
-            create_broker(mode=TradingMode.LIVE)
+        # Should return a PaperBroker (fallback)
+        assert isinstance(broker, PaperBroker)
+        assert broker.get_balance() == 5000
 
     def test_invalid_mode(self):
         """Test that invalid mode raises ValueError."""