fix(CORE-002C): align historical units with workspace weight

app/domain/backtesting_math.py

@@ -3,8 +3,9 @@ from __future__ import annotations
 from dataclasses import dataclass
 from decimal import Decimal
 
-from app.domain.units import BaseCurrency, Money, _coerce_currency, decimal_from_float, to_decimal
+from app.domain.units import BaseCurrency, Money, Weight, WeightUnit, _coerce_currency, decimal_from_float, to_decimal
 from app.models.backtest import BacktestPortfolioState
+from app.models.portfolio import PortfolioConfig
 
 
 @dataclass(frozen=True, slots=True)
@@ -94,6 +95,23 @@ def asset_quantity_from_floats(portfolio_value: float, entry_spot: float, symbol
     return float(asset_quantity_from_money(notional, spot).amount)
 
 
+def asset_quantity_from_workspace_config(config: PortfolioConfig, *, entry_spot: float, symbol: str) -> float:
+    if config.gold_ounces is not None and config.gold_ounces > 0:
+        try:
+            from app.domain.instruments import asset_quantity_from_weight
+
+            quantity = asset_quantity_from_weight(
+                symbol,
+                Weight(amount=decimal_from_float(float(config.gold_ounces)), unit=WeightUnit.OUNCE_TROY),
+            )
+            return float(quantity.amount)
+        except ValueError:
+            pass
+    if config.gold_value is not None:
+        return asset_quantity_from_floats(float(config.gold_value), entry_spot, symbol)
+    raise ValueError("Workspace config must provide collateral weight or value")
+
+
 def materialize_backtest_portfolio_state(
     *,
     symbol: str,

app/pages/backtests.py

@@ -5,7 +5,7 @@ from datetime import date, datetime
 from fastapi.responses import RedirectResponse
 from nicegui import ui
 
-from app.domain.backtesting_math import asset_quantity_from_floats
+from app.domain.backtesting_math import asset_quantity_from_workspace_config
 from app.models.workspace import get_workspace_repository
 from app.pages.common import dashboard_page, render_workspace_recovery
 from app.services.backtesting.ui_service import BacktestPageRunResult, BacktestPageService
@@ -66,8 +66,8 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
     config = repo.load_portfolio_config(workspace_id) if workspace_id else None
     default_entry_spot = service.derive_entry_spot("GLD", date(2024, 1, 2), date(2024, 1, 8))
     default_units = (
-        asset_quantity_from_floats(float(config.gold_value or 0.0), default_entry_spot, "GLD")
+        asset_quantity_from_workspace_config(config, entry_spot=default_entry_spot, symbol="GLD")
-        if config and config.gold_value is not None and default_entry_spot > 0
+        if config is not None and default_entry_spot > 0
         else 1000.0
     )
     default_loan = float(config.loan_amount) if config else 68000.0
@@ -217,7 +217,7 @@ def _render_backtests_page(workspace_id: str | None = None) -> None:
                 )
             except (ValueError, KeyError):
                 return
-            units_input.value = asset_quantity_from_floats(float(config.gold_value), entry_spot, "GLD")
+            units_input.value = asset_quantity_from_workspace_config(config, entry_spot=entry_spot, symbol="GLD")
             entry_spot_hint.set_text(f"Auto-derived entry spot: ${entry_spot:,.2f}")
 
         def run_backtest() -> None:

app/pages/event_comparison.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 from fastapi.responses import RedirectResponse
 from nicegui import ui
 
-from app.domain.backtesting_math import asset_quantity_from_floats
+from app.domain.backtesting_math import asset_quantity_from_workspace_config
 from app.models.workspace import get_workspace_repository
 from app.pages.common import dashboard_page, render_workspace_recovery
 from app.services.event_comparison_ui import EventComparisonPageService
@@ -54,8 +54,8 @@ def _render_event_comparison_page(workspace_id: str | None = None) -> None:
         )
         default_entry_spot = default_preview.initial_portfolio.entry_spot
     default_units = (
-        asset_quantity_from_floats(float(config.gold_value or 0.0), default_entry_spot, "GLD")
+        asset_quantity_from_workspace_config(config, entry_spot=default_entry_spot, symbol="GLD")
-        if config and config.gold_value is not None and default_entry_spot > 0
+        if config is not None and default_entry_spot > 0
         else 1000.0
     )
 
@@ -129,7 +129,7 @@ def _render_event_comparison_page(workspace_id: str | None = None) -> None:
             template_select.value = list(service.default_template_selection(str(option["slug"])))
             try:
                 preview_units = float(units_input.value or 0.0)
-                if workspace_id and config is not None and config.gold_value is not None:
+                if workspace_id and config is not None:
                     preview_scenario = service.preview_scenario(
                         preset_slug=str(option["slug"]),
                         template_slugs=selected_template_slugs(),
@@ -137,10 +137,10 @@ def _render_event_comparison_page(workspace_id: str | None = None) -> None:
                         loan_amount=float(loan_input.value or 0.0),
                         margin_call_ltv=float(ltv_input.value or 0.0),
                     )
-                    preview_units = asset_quantity_from_floats(
+                    preview_units = asset_quantity_from_workspace_config(
-                        float(config.gold_value),
+                        config,
-                        float(preview_scenario.initial_portfolio.entry_spot),
+                        entry_spot=float(preview_scenario.initial_portfolio.entry_spot),
-                        "GLD",
+                        symbol="GLD",
                     )
                     units_input.value = preview_units
                 scenario = service.preview_scenario(

tests/test_backtesting_units.py

@@ -9,9 +9,11 @@ from app.domain.backtesting_math import (
     PricePerAsset,
     asset_quantity_from_floats,
     asset_quantity_from_money,
+    asset_quantity_from_workspace_config,
     materialize_backtest_portfolio_state,
 )
 from app.domain.units import BaseCurrency, Money
+from app.models.portfolio import PortfolioConfig
 from app.services.backtesting.comparison import EventComparisonService
 from app.services.backtesting.historical_provider import SyntheticHistoricalProvider
 from app.services.event_comparison_ui import EventComparisonFixtureHistoricalPriceSource
@@ -47,6 +49,20 @@ def test_asset_quantity_from_floats_matches_workspace_backtest_conversion() -> N
     assert asset_quantity_from_floats(968000.0, 100.0, "GLD") == 9680.0
 
 
+def test_asset_quantity_from_workspace_config_uses_instrument_weight_conversion_for_gld() -> None:
+    config = PortfolioConfig(
+        gold_ounces=220.0,
+        entry_price=4400.0,
+        entry_basis_mode="weight",
+        loan_amount=222000.0,
+        margin_threshold=0.80,
+    )
+
+    quantity = asset_quantity_from_workspace_config(config, entry_spot=100.0, symbol="GLD")
+
+    assert quantity == 2200.0
+
+
 def test_materialize_backtest_portfolio_state_uses_typed_asset_boundary() -> None:
     portfolio = materialize_backtest_portfolio_state(
         symbol="GLD",

tests/test_e2e_playwright.py

@@ -119,20 +119,20 @@ def test_homepage_and_options_page_render() -> None:
         page.screenshot(path=str(ARTIFACTS / "settings.png"), full_page=True)
 
         page.goto(f"{workspace_url}/backtests", wait_until="networkidle", timeout=30000)
-        expect(page.get_by_label("Underlying units")).to_have_value("9680")
+        expect(page.get_by_label("Underlying units")).to_have_value("2200")
         expect(page.get_by_label("Loan amount")).to_have_value("222000")
         expect(page.get_by_label("Margin call LTV")).to_have_value("0.8")
         backtests_workspace_text = page.locator("body").inner_text(timeout=15000)
         assert "Scenario Summary" in backtests_workspace_text
-        assert "$968,000" in backtests_workspace_text
+        assert "$220,000" in backtests_workspace_text
 
         page.goto(f"{workspace_url}/event-comparison", wait_until="networkidle", timeout=30000)
-        expect(page.get_by_label("Underlying units")).to_have_value("9680")
+        expect(page.get_by_label("Underlying units")).to_have_value("2200")
         expect(page.get_by_label("Loan amount")).to_have_value("222000")
         expect(page.get_by_label("Margin call LTV")).to_have_value("0.8")
         event_workspace_text = page.locator("body").inner_text(timeout=15000)
         assert "$222,000" in event_workspace_text
-        assert "9,680" in event_workspace_text
+        assert "2,200" in event_workspace_text
         assert "80.0%" in event_workspace_text
 
         page.goto(workspace_url, wait_until="domcontentloaded", timeout=30000)

tests/test_workspace.py

@@ -224,7 +224,7 @@ def test_workspace_routes_seed_page_defaults_from_workspace_portfolio_config(tmp
 
     assert backtests_response.status_code == 200
     assert "Workspace defaults seed underlying units, loan amount, and margin threshold." in backtests_response.text
-    assert "9680" in backtests_response.text or "9,680" in backtests_response.text
+    assert "2200" in backtests_response.text or "2,200" in backtests_response.text
     assert "222000" in backtests_response.text or "222,000" in backtests_response.text
     assert "0.8" in backtests_response.text or "80.0%" in backtests_response.text
 
@@ -233,8 +233,8 @@ def test_workspace_routes_seed_page_defaults_from_workspace_portfolio_config(tmp
     assert "Underlying units" in event_response.text
     assert "Loan amount" in event_response.text
     assert "222,000" in event_response.text or "222000" in event_response.text
-    assert "9,680" in event_response.text or "9680" in event_response.text
+    assert "2,200" in event_response.text or "2200" in event_response.text
-    assert "80.0%" in event_response.text
+    assert "80.0%" in event_response.text or "0.8" in event_response.text
 
 
 def test_hedge_page_upgrades_cached_gld_quote_and_uses_converted_spot(tmp_path, monkeypatch) -> None: