feat(CORE-001C): type historical unit materialization

app/services/backtesting/ui_service.py

@@ -3,8 +3,8 @@ from __future__ import annotations
 from dataclasses import dataclass
 from datetime import date
 
+from app.domain.backtesting_math import materialize_backtest_portfolio_state
 from app.models.backtest import (
-    BacktestPortfolioState,
     BacktestRunResult,
     BacktestScenario,
     ProviderRef,
@@ -116,6 +116,13 @@ class BacktestPageService:
 
         template = self.template_service.get_template(template_slug)
         entry_spot = self.derive_entry_spot(normalized_symbol, start_date, end_date)
+        initial_portfolio = materialize_backtest_portfolio_state(
+            symbol=normalized_symbol,
+            underlying_units=underlying_units,
+            entry_spot=entry_spot,
+            loan_amount=loan_amount,
+            margin_call_ltv=margin_call_ltv,
+        )
         scenario = BacktestScenario(
             scenario_id=(
                 f"{normalized_symbol.lower()}-{start_date.isoformat()}-{end_date.isoformat()}-{template.slug}"
@@ -124,13 +131,7 @@ class BacktestPageService:
             symbol=normalized_symbol,
             start_date=start_date,
             end_date=end_date,
-            initial_portfolio=BacktestPortfolioState(
-                currency="USD",
-                underlying_units=underlying_units,
-                entry_spot=entry_spot,
-                loan_amount=loan_amount,
-                margin_call_ltv=margin_call_ltv,
-            ),
+            initial_portfolio=initial_portfolio,
             template_refs=(TemplateRef(slug=template.slug, version=template.version),),
             provider_ref=ProviderRef(provider_id="synthetic_v1", pricing_mode="synthetic_bs_mid"),
         )