feat: add audit events and runtime state snapshots to database

- Introduced new tables for audit events and runtime state snapshots in the database schema.
- Created data classes for AuditRecord and RuntimeStateRecord to represent the new entities.
- Implemented AuditRepository and RuntimeStateRepository for inserting and retrieving records.
- Enhanced the dashboard to include an audit trail section, displaying recent audit events.
- Added tests for the new audit repository and runtime lifecycle functionalities.
- Updated settings validation to ensure proper configuration for alerting features.
- Integrated alert notifications across various components, including execution sequencer and loss limits.

tests/unit/test_alert_notifier.py

@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+
+import pytest
+
+from arbitrade.alerting.notifier import AlertEvent, AlertNotifier
+
+
+@dataclass(slots=True)
+class _FakeChannel:
+    events: list[AlertEvent] = field(default_factory=list)
+    fail: bool = False
+
+    async def send(self, event: AlertEvent) -> None:
+        if self.fail:
+            raise RuntimeError("channel send failed")
+        self.events.append(event)
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_sends_event_when_enabled() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], enabled=True, min_severity="info")
+
+    sent = await notifier.notify(
+        category="trade",
+        severity="info",
+        title="Trade complete",
+        message="Completed all legs.",
+    )
+
+    assert sent is True
+    assert len(channel.events) == 1
+    assert channel.events[0].category == "trade"
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_respects_severity_and_category_filters() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier(
+        [channel],
+        enabled=True,
+        min_severity="error",
+        category_flags={"trade": False, "error": True},
+    )
+
+    low = await notifier.notify(
+        category="error",
+        severity="warning",
+        title="Low",
+        message="Ignored by severity.",
+    )
+    filtered = await notifier.notify(
+        category="trade",
+        severity="critical",
+        title="Trade",
+        message="Ignored by category.",
+    )
+    high = await notifier.notify(
+        category="error",
+        severity="critical",
+        title="High",
+        message="Delivered.",
+    )
+
+    assert low is False
+    assert filtered is False
+    assert high is True
+    assert len(channel.events) == 1
+    assert channel.events[0].title == "High"
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_applies_dedup_window() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], dedup_seconds=60.0)
+
+    first = await notifier.notify(
+        category="error",
+        severity="error",
+        title="Burst",
+        message="Same message",
+    )
+    second = await notifier.notify(
+        category="error",
+        severity="error",
+        title="Burst",
+        message="Same message",
+    )
+
+    assert first is True
+    assert second is False
+    assert len(channel.events) == 1
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_returns_false_when_all_channels_fail() -> None:
+    notifier = AlertNotifier([_FakeChannel(fail=True), _FakeChannel(fail=True)])
+
+    sent = await notifier.notify(
+        category="error",
+        severity="critical",
+        title="Failure",
+        message="Both channels fail.",
+    )
+
+    assert sent is False
+
+
+@pytest.mark.asyncio
+async def test_alert_notifier_exposes_status_snapshot_for_dashboard() -> None:
+    channel = _FakeChannel()
+    notifier = AlertNotifier([channel], enabled=True, min_severity="info", dedup_seconds=30.0)
+
+    await notifier.notify(
+        category="system",
+        severity="warning",
+        title="Reconnect",
+        message="Socket restored.",
+    )
+
+    status = notifier.status_snapshot()
+
+    assert status["enabled"] is True
+    assert status["has_channels"] is True
+    assert status["configured_channels"] == ["_FakeChannel"]
+    assert status["last_result"] == "success"
+    assert status["last_attempted_at"] is not None
+    assert status["last_success_at"] is not None
+    assert status["last_event"] is not None