fix(pricing): correct relative hedge payoff calculations

tests/test_hedge_metrics.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from app.domain.portfolio_math import resolve_portfolio_spot_from_quote
 from app.models.portfolio import PortfolioConfig
 from app.pages.common import strategy_metrics
-from app.pages.hedge import _waterfall_options
+from app.pages.hedge import _cost_benefit_options, _waterfall_options
 
 
 def test_protective_put_atm_minus_20pct_improves_equity() -> None:
@@ -11,15 +11,15 @@ def test_protective_put_atm_minus_20pct_improves_equity() -> None:
 
     assert metrics["scenario_price"] == 172.0
     assert metrics["unhedged_equity"] == 27_000.0
-    assert metrics["hedged_equity"] == 58_750.0
+    assert metrics["hedged_equity"] == 63_750.0
     assert metrics["hedged_equity"] > metrics["unhedged_equity"]
     assert metrics["waterfall_steps"] == [
         ("Base equity", 70_000.0),
         ("Spot move", -43_000.0),
-        ("Option payoff", 38_000.0),
+        ("Option payoff", 43_000.0),
         ("Call cap", 0.0),
         ("Hedge cost", -6_250.0),
-        ("Net equity", 58_750.0),
+        ("Net equity", 63_750.0),
     ]
 
 
@@ -28,11 +28,39 @@ def test_hedge_waterfall_uses_zero_based_contribution_bars() -> None:
 
     assert len(options["series"]) == 1
     assert options["series"][0]["type"] == "bar"
+    assert options["series"][0]["label"]["show"] is True
     values = options["series"][0]["data"]
-    assert values[2]["value"] == 38_000.0
+    assert values[2]["value"] == 43_000.0
     assert values[2]["itemStyle"]["color"] == "#22c55e"
 
 
+def test_cost_benefit_chart_shows_positive_downside_benefit_when_puts_are_in_the_money() -> None:
+    metrics = strategy_metrics(
+        "protective_put_atm",
+        -20,
+        portfolio={
+            **{
+                "gold_value": 968000.0,
+                "loan_amount": 145000.0,
+                "ltv_ratio": 145000.0 / 968000.0,
+                "net_equity": 823000.0,
+                "spot_price": 4400.0,
+                "gold_units": 220.0,
+                "margin_call_ltv": 0.75,
+                "margin_call_price": 878.79,
+                "cash_buffer": 18500.0,
+                "hedge_budget": 8000.0,
+            }
+        },
+    )
+    options = _cost_benefit_options(metrics)
+
+    assert options["xAxis"]["name"] == "Collateral spot"
+    assert options["yAxis"]["name"] == "Net hedge benefit / oz"
+    assert options["series"][0]["data"][0] > 0
+    assert options["series"][0]["data"][1] > 0
+
+
 def test_hedge_quote_resolution_converts_gld_share_price_to_ozt_spot() -> None:
     """Hedge page should convert GLD share quotes to USD/ozt for display."""
     config = PortfolioConfig(entry_price=4400.0, gold_ounces=220.0, entry_basis_mode="weight", loan_amount=145000.0)