improvements jan2025 (#6)

* feat(controller): add lazy watcher, improve resource usage and add pattern validation

- [x] Add cache sync health check for readiness probe verification
- [x] Create namespace lister with API reader support for fresh label queries
- [x] Add pattern validation with warning logs for invalid glob patterns
- [x] Implement lazy watcher initialization mode to scan for active resources
- [x] Add requeue delay to namespace reconciler for cache settlement
- [x] Replace custom containsString with slices.Contains from stdlib
- [x] Add structured logging context to reconcilers (kind, group, version)
- [x] Improve error variable naming for clarity in nested conditions
- [x] Add nil-safe label access in namespace reconciler setup
- [x] Add APIReader to namespace and source reconcilers for fresh data
- [x] Improve type assertions with proper error handling in mirror operations
- [x] Reorder struct fields for consistency and readability
- [x] Add comprehensive pattern validation tests and validation API

* feat(controller): add lazy watcher, improve resource usage and add pattern validation

- [x] Add circuit breaker for reconciliation failure tracking and prevention
- [x] Implement granular registration state tracking (not-registered, source-only, fully-registered)
- [x] Add lazy controller initialization for active resource types only
- [x] Consolidate namespace listing into single API call for efficiency
- [x] Add mirror creation verification to catch webhook rejections
- [x] Implement high-cardinality resource detection and warnings
- [x] Add source deletion check in mirror reconciler to prevent races
- [x] Preserve transformation annotations on errors in mirror reconciliation
- [x] Expand constants documentation with labels vs annotations design rationale
- [x] Add comprehensive test coverage for circuit breaker and registration states
- [x] Add mutation-safety tests for hash computation

* fixup! feat(controller): add lazy watcher, improve resource usage and add pattern validation

pkg/controller/namespace_reconciler_test.go

@@ -282,9 +282,9 @@ func makeUnstructuredMirror(name, namespace, sourceNs, sourceName string) *unstr
 
 // Mock namespace lister for testing
 type mockNamespaceLister struct {
-	namespaces   []string
 	allowMirrors map[string]bool
 	optOut       map[string]bool
+	namespaces   []string
 }
 
 func (m *mockNamespaceLister) ListNamespaces(ctx context.Context) ([]string, error) {
@@ -310,3 +310,25 @@ func (m *mockNamespaceLister) ListOptOutNamespaces(ctx context.Context) ([]strin
 	}
 	return result, nil
 }
+
+func (m *mockNamespaceLister) ListNamespacesWithLabels(ctx context.Context) (*NamespaceInfo, error) {
+	info := &NamespaceInfo{
+		All:          m.namespaces,
+		AllowMirrors: make([]string, 0),
+		OptOut:       make([]string, 0),
+	}
+
+	for ns, allowed := range m.allowMirrors {
+		if allowed {
+			info.AllowMirrors = append(info.AllowMirrors, ns)
+		}
+	}
+
+	for ns, optedOut := range m.optOut {
+		if optedOut {
+			info.OptOut = append(info.OptOut, ns)
+		}
+	}
+
+	return info, nil
+}