feat(CORE-001D3B): surface alert history degraded state

tests/test_alerts.py

@@ -5,6 +5,7 @@ from pathlib import Path
 
 import pytest
 
+from app.models.alerts import AlertHistoryLoadError, AlertHistoryRepository
 from app.models.portfolio import PortfolioConfig
 from app.services.alerts import AlertService, _normalize_alert_evaluation_input, build_portfolio_alert_context
 
@@ -169,6 +170,70 @@ def test_alert_service_escalates_to_critical_and_keeps_history(alert_service: Al
     assert critical_status.history[0].ltv_ratio == pytest.approx(0.7525, rel=1e-6)
 
 
+def test_alert_history_repository_raises_on_corrupt_history_file(tmp_path: Path) -> None:
+    history_path = tmp_path / "alert_history.json"
+    history_path.write_text("{not valid json", encoding="utf-8")
+    repository = AlertHistoryRepository(history_path=history_path)
+
+    with pytest.raises(AlertHistoryLoadError, match="Alert history is not valid JSON"):
+        repository.load()
+
+
+def test_alert_service_marks_history_unavailable_on_corrupt_storage(alert_service: AlertService) -> None:
+    alert_service.repository.history_path.write_text("{not valid json", encoding="utf-8")
+    config = PortfolioConfig(
+        gold_value=215_000.0,
+        entry_price=215.0,
+        loan_amount=151_000.0,
+        ltv_warning=0.70,
+        margin_threshold=0.75,
+    )
+    portfolio = build_portfolio_alert_context(
+        config,
+        spot_price=215.0,
+        source="test",
+        updated_at="2026-03-24T12:00:00Z",
+    )
+
+    status = alert_service.evaluate(config, portfolio)
+
+    assert status.severity == "warning"
+    assert status.history == []
+    assert status.history_unavailable is True
+    assert (
+        status.history_notice
+        == "Alert history is temporarily unavailable due to a storage error. New alerts are not being recorded."
+    )
+    assert alert_service.repository.history_path.read_text(encoding="utf-8") == "{not valid json"
+
+
+def test_alert_service_preview_marks_history_unavailable_on_corrupt_storage(alert_service: AlertService) -> None:
+    alert_service.repository.history_path.write_text("{not valid json", encoding="utf-8")
+    config = PortfolioConfig(
+        gold_value=215_000.0,
+        entry_price=215.0,
+        loan_amount=151_000.0,
+        ltv_warning=0.70,
+        margin_threshold=0.75,
+    )
+    portfolio = build_portfolio_alert_context(
+        config,
+        spot_price=215.0,
+        source="settings-preview",
+        updated_at="",
+    )
+
+    status = alert_service.evaluate(config, portfolio, persist=False)
+
+    assert status.severity == "warning"
+    assert [event.severity for event in status.history] == ["warning"]
+    assert status.history_unavailable is True
+    assert (
+        status.history_notice
+        == "Alert history is temporarily unavailable due to a storage error. New alerts are not being recorded."
+    )
+
+
 def test_alert_service_preserves_persisted_history_during_ok_evaluation(alert_service: AlertService) -> None:
     warning_config = PortfolioConfig(
         gold_value=215_000.0,