feat(CORE-001D3A): normalize alerts and settings service boundaries

tests/test_alerts.py

@@ -1,11 +1,12 @@
 from __future__ import annotations
 
+from decimal import Decimal
 from pathlib import Path
 
 import pytest
 
 from app.models.portfolio import PortfolioConfig
-from app.services.alerts import AlertService, build_portfolio_alert_context
+from app.services.alerts import AlertService, _normalize_alert_evaluation_input, build_portfolio_alert_context
 
 
 @pytest.fixture
@@ -13,6 +14,39 @@ def alert_service(tmp_path: Path) -> AlertService:
     return AlertService(history_path=tmp_path / "alert_history.json")
 
 
+def test_normalize_alert_evaluation_input_coerces_numeric_boundary_values() -> None:
+    config = PortfolioConfig(gold_value=215_000.0, entry_price=215.0, loan_amount=151_000.0)
+
+    normalized = _normalize_alert_evaluation_input(
+        config,
+        {
+            "ltv_ratio": "0.7023",
+            "spot_price": "215.0",
+            "quote_updated_at": 123,
+        },
+    )
+
+    assert normalized.ltv_ratio == Decimal("0.7023")
+    assert normalized.spot_price == Decimal("215.0")
+    assert normalized.updated_at == "123"
+    assert normalized.warning_threshold == Decimal("0.7")
+    assert normalized.critical_threshold == Decimal("0.75")
+
+
+def test_normalize_alert_evaluation_input_rejects_bool_values() -> None:
+    config = PortfolioConfig(gold_value=215_000.0, entry_price=215.0, loan_amount=151_000.0)
+
+    with pytest.raises(TypeError, match="portfolio.ltv_ratio must be numeric, got bool"):
+        _normalize_alert_evaluation_input(
+            config,
+            {
+                "ltv_ratio": True,
+                "spot_price": 215.0,
+                "quote_updated_at": "2026-03-24T12:00:00Z",
+            },
+        )
+
+
 def test_alert_service_reports_ok_when_ltv_is_below_warning(alert_service: AlertService) -> None:
     config = PortfolioConfig(gold_value=215_000.0, entry_price=215.0, loan_amount=120_000.0)
     portfolio = build_portfolio_alert_context(