feat: show suffix-matched metric coverage in host info threshold table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_http_host_info.py

@@ -11,12 +11,13 @@ class _FakeConn:
 
 class _FakeHost:
     def __init__(self, name="myhost", owner=None, managers=None,
-                 connections=None, os_data=None):
+                 connections=None, os_data=None, plugin_data=None):
         self.name = name
         self.owner = owner
         self.managers = managers or []
         self.connections = connections or {}
         self._os_data = os_data
+        self.plugin_data = plugin_data or {}
 
     def get_latest_plugin_data(self, plugin_name):
         if plugin_name == "os_info" and self._os_data is not None:
@@ -127,3 +128,47 @@ def test_build_host_info_nagios_operator_serialized():
     host = _FakeHost()
     result = _build_host_info(host, threshold_checker=checker)
     assert result["thresholds"][0]["operator"] == "nagios"
+
+
+def test_build_host_info_covers_suffix_matched_metrics():
+    """memory_monitor.percent threshold covers swap_percent via suffix match."""
+    from hbd.server.threshold import ThresholdConfig
+    tc_pct = ThresholdConfig("memory_monitor.percent", warning=85.0, critical=95.0)
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {"memory_monitor.percent": tc_pct}
+
+    host = _FakeHost(
+        connections={},
+        os_data=None,
+    )
+    # Simulate plugin_data with both percent and swap_percent fields
+    host.plugin_data = {
+        "memory_monitor": [(1234567890.0, {
+            "percent": 80.0,
+            "swap_percent": 25.0,
+            "available_mb": 2000,
+        })]
+    }
+
+    result = _build_host_info(host, threshold_checker=checker)
+    assert result["thresholds"] is not None
+    t = result["thresholds"][0]
+    assert t["metric"] == "memory_monitor.percent"
+    assert t["covers"] == ["memory_monitor.swap_percent"]
+
+
+def test_build_host_info_covers_empty_when_exact_matches_only():
+    """No covers when all plugin fields match their threshold exactly."""
+    from hbd.server.threshold import ThresholdConfig
+    tc_pct = ThresholdConfig("memory_monitor.percent", warning=85.0, critical=95.0)
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {"memory_monitor.percent": tc_pct}
+
+    host = _FakeHost()
+    host.plugin_data = {
+        "memory_monitor": [(1234567890.0, {"percent": 80.0})]
+    }
+
+    result = _build_host_info(host, threshold_checker=checker)
+    t = result["thresholds"][0]
+    assert t["covers"] == []