layer1: add namespace manager summary

pkg/utils/namespace_manager.go

@@ -59,6 +59,7 @@ func (s NamespaceSubscriberFuncs) OnNamespaceResync(ctx context.Context, record
 type NamespaceManager interface {
 	Snapshot() []string
 	SnapshotRecords() []NamespaceRecord
+	Summary() NamespaceManagerSummary
 	Get(name string) (NamespaceRecord, bool)
 	Bootstrap(namespaces []string, source NamespaceSource, observedAt time.Time) []NamespaceRecord
 	BootstrapAndDispatch(ctx context.Context, namespaces []string, source NamespaceSource, observedAt time.Time) ([]NamespaceRecord, error)
@@ -240,6 +241,19 @@ func StartManagedNamespaceWatcher(ctx context.Context, logger *zap.Logger, compo
 	})
 }
 
+func (m *inMemoryNamespaceManager) Summary() NamespaceManagerSummary {
+	records := m.SnapshotRecords()
+	summary := NamespaceManagerSummary{
+		TotalNamespaces: len(records),
+		PhaseCounts:     make(map[NamespacePhase]int),
+		Subscribers:     m.SnapshotSubscribers(),
+	}
+	for _, record := range records {
+		summary.PhaseCounts[record.Phase]++
+	}
+	return summary
+}
+
 func (m *inMemoryNamespaceManager) Subscribe(subscriber NamespaceSubscriber) {
 	m.mu.Lock()
 	defer m.mu.Unlock()