feat(CORE-001D): close remaining boundary cleanup slices

tests/test_backtest_ui.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from datetime import date
+from decimal import Decimal
 
 import pytest
 
@@ -10,6 +11,24 @@ from app.services.backtesting.ui_service import BacktestPageService
 from tests.helpers_backtest_sources import StaticBacktestSource
 
 
+def test_backtest_page_service_accepts_decimal_boundary_values() -> None:
+    service = BacktestPageService()
+
+    result = service.run_read_only_scenario(
+        symbol="GLD",
+        start_date=date(2024, 1, 2),
+        end_date=date(2024, 1, 8),
+        template_slug="protective-put-atm-12m",
+        underlying_units=Decimal("1000.0"),
+        loan_amount=Decimal("68000.0"),
+        margin_call_ltv=Decimal("0.75"),
+    )
+
+    assert result.scenario.initial_portfolio.underlying_units == 1000.0
+    assert result.scenario.initial_portfolio.loan_amount == 68000.0
+    assert result.scenario.initial_portfolio.margin_call_ltv == 0.75
+
+
 def test_backtest_page_service_uses_fixture_window_for_deterministic_run() -> None:
     service = BacktestPageService()