Fix monitor loop double-sleep on error; add grep -F regression test

On exception the monitor slept 30s inside the except block then fell
through to time.sleep(poll_interval), giving a 150s recovery gap instead
of 30s. Adding continue after the error sleep fixes this.

Also adds a regression test asserting dmesg filtering uses grep -F --
so a future refactor cannot silently reintroduce the regex wildcard bug.

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

app.py

@@ -174,17 +174,26 @@ _PAGE_LIMIT = 200  # max events returned per request
 
 
 def _annotate_suppressions(events: list, suppressions: list) -> None:
-    """Annotate each event dict in-place with an is_suppressed bool."""
+    """Annotate each event dict in-place with an is_suppressed bool.
+
+    Mirrors the suppression check order in monitor.py exactly:
+      interface_down  → interface OR host
+      unifi_device_*  → unifi_device
+      everything else → host
+    """
     for ev in events:
-        sup_type = (
-            'unifi_device' if ev.get('event_type') == 'unifi_device_offline'
-            else 'interface' if ev.get('event_type') == 'interface_down'
-            else 'host'
-        )
-        ev['is_suppressed'] = db.check_suppressed(
-            suppressions, sup_type,
-            ev.get('target_name', ''), ev.get('target_detail', '') or '',
-        )
+        etype = ev.get('event_type', '')
+        name = ev.get('target_name', '')
+        detail = ev.get('target_detail', '') or ''
+        if etype == 'interface_down':
+            ev['is_suppressed'] = (
+                db.check_suppressed(suppressions, 'interface', name, detail) or
+                db.check_suppressed(suppressions, 'host', name)
+            )
+        elif etype == 'unifi_device_offline':
+            ev['is_suppressed'] = db.check_suppressed(suppressions, 'unifi_device', name, detail)
+        else:
+            ev['is_suppressed'] = db.check_suppressed(suppressions, 'host', name, detail)
 
 
 # ---------------------------------------------------------------------------

monitor.py

@@ -970,6 +970,7 @@ class NetworkMonitor:
             except Exception as e:
                 logger.error(f'Monitor loop error: {e}', exc_info=True)
                 time.sleep(30)
+                continue
 
             time.sleep(self.poll_interval)
 

tests/test_diagnose.py

@@ -36,6 +36,12 @@ class TestBuildSshCommand:
         cmd = DiagnosticsRunner.build_ssh_command('10.0.0.1', 'eth0')
         assert 'ethtool' in cmd
 
+    def test_dmesg_uses_fixed_string_grep(self):
+        # grep -F prevents iface names with dots (e.g. eth0.1) being treated as
+        # regex wildcards; -- prevents leading - from being parsed as a flag
+        cmd = DiagnosticsRunner.build_ssh_command('10.0.0.1', 'eth0')
+        assert 'grep -F --' in cmd
+
 
 # ── parse_output ─────────────────────────────────────────────────────────────