layer1: add namespace manager summary

doc/thinking/2026-04-26-namespace-manager-step45.md

@@ -0,0 +1,20 @@
+# 2026-04-26 — NamespaceManager rewrite, step 45
+
+## Цель шага
+
+Подготовить компактный status/debug surface для `NamespaceManager`.
+
+## Что меняем
+
+1. Добавляем `NamespaceManagerSummary`.
+2. В `NamespaceManager` добавляем `Summary()`.
+3. Summary считает:
+   - общее число namespace-ов;
+   - число по phase;
+   - список subscriber-ов.
+4. Добавляем unit tests.
+
+## Что НЕ меняем
+
+- не публикуем summary наружу через HTTP;
+- не меняем watcher behavior.

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()

pkg/utils/namespace_manager_model.go

@@ -73,6 +73,12 @@ type NamespaceEvent struct {
 	ObservedAt time.Time
 }
 
+type NamespaceManagerSummary struct {
+	TotalNamespaces int
+	PhaseCounts     map[NamespacePhase]int
+	Subscribers     []string
+}
+
 func NewNamespaceEvent(eventType NamespaceEventType, name string, labels map[string]string, source NamespaceSource, observedAt time.Time) NamespaceEvent {
 	return NamespaceEvent{
 		Type:       eventType,

pkg/utils/namespace_manager_model_test.go

@@ -154,3 +154,10 @@ func TestNamespaceRemovalStrategyValues(t *testing.T) {
 		t.Fatalf("unexpected dispatch-remove strategy value")
 	}
 }
+
+func TestNamespaceManagerSummaryZeroValue(t *testing.T) {
+	summary := NamespaceManagerSummary{}
+	if summary.TotalNamespaces != 0 {
+		t.Fatalf("expected zero total namespaces")
+	}
+}

pkg/utils/namespace_manager_test.go

@@ -59,6 +59,10 @@ func TestNamespaceManagerSnapshotAndGet(t *testing.T) {
 	if record.Name != "tenant-a" || record.Phase != NamespacePhaseDiscovered {
 		t.Fatalf("unexpected record returned: %+v", record)
 	}
+	summary := manager.Summary()
+	if summary.TotalNamespaces != 2 {
+		t.Fatalf("expected summary total namespaces to be 2, got %d", summary.TotalNamespaces)
+	}
 }
 
 func TestNamespaceManagerUpsertIncrementsGeneration(t *testing.T) {
@@ -448,6 +452,29 @@ func TestPrepareManagedNamespaceWatcher(t *testing.T) {
 	}
 }
 
+func TestNamespaceManagerSummary(t *testing.T) {
+	manager := NewNamespaceManager()
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-a", Source: NamespaceSourceWatcher})
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-b", Source: NamespaceSourceWatcher})
+	_, _ = manager.MarkPartRegistering("tenant-a", "router")
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventRemove, Name: "tenant-b", Source: NamespaceSourceWatcher})
+	manager.Subscribe(&testNamespaceSubscriber{name: "router"})
+
+	summary := manager.Summary()
+	if summary.TotalNamespaces != 2 {
+		t.Fatalf("expected total namespaces 2, got %d", summary.TotalNamespaces)
+	}
+	if summary.PhaseCounts[NamespacePhaseRegistering] != 1 {
+		t.Fatalf("expected one registering namespace")
+	}
+	if summary.PhaseCounts[NamespacePhaseRemoved] != 1 {
+		t.Fatalf("expected one removed namespace")
+	}
+	if !reflect.DeepEqual([]string{"router"}, summary.Subscribers) {
+		t.Fatalf("expected router subscriber in summary")
+	}
+}
+
 func TestNamespaceManagerDispatchAdd(t *testing.T) {
 	manager := NewNamespaceManager()
 	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-a", Source: NamespaceSourceWatcher})