add chache for last known good in sqlite..

tests/test_monitor.py

@@ -4,7 +4,8 @@ import unittest
 from pathlib import Path
 from unittest.mock import patch
 
-from fgai.monitor import add_llm_assessment, build_status, write_status
+from fgai.history import StatusSnapshotStore
+from fgai.monitor import add_llm_assessment, build_status, cached_status_with_error, write_status
 
 
 class MonitorTests(unittest.TestCase):
@@ -109,6 +110,26 @@ class MonitorTests(unittest.TestCase):
             self.assertEqual(advisor["status"], "error")
             self.assertIn("timeout", advisor["error"])
 
+    def test_cached_status_with_error_keeps_last_good_dashboard_data(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            cache_path = str(Path(tmp) / "status-cache.sqlite3")
+            StatusSnapshotStore(cache_path).save(
+                "last_good",
+                {
+                    "summary": {"total": 42},
+                    "capabilities": {"graylog_mcp": {"status": "connected"}},
+                    "cross_source_correlations": [{"entity": "10.0.0.1"}],
+                },
+            )
+
+            status = cached_status_with_error(cache_path, {"status": "error", "error": "mcp down"})
+
+            self.assertIsNotNone(status)
+            self.assertEqual(status["summary"]["total"], 42)
+            self.assertTrue(status["stale"])
+            self.assertEqual(status["capabilities"]["graylog_mcp"]["status"], "error")
+            self.assertTrue(status["status_cache"]["served_from_cache"])
+
 
 if __name__ == "__main__":
     unittest.main()