[cmd] recover existing cluster name from namespace annotation on reinstall

Read the apoxy.dev/cluster-name annotation from the target namespace
before calling the onboarding API, so reinstalls preserve the original
cluster name instead of generating a new random one.

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

Author: dilyevsky

pkg/cmd/k8s.go

@@ -23,6 +23,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	runtimejson "k8s.io/apimachinery/pkg/runtime/serializer/json"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/discovery/cached/memory"
 	"k8s.io/client-go/dynamic"
@@ -35,6 +36,8 @@ import (
 	"github.com/apoxy-dev/apoxy/config"
 )
 
+const clusterNameAnnotation = "apoxy.dev/cluster-name"
+
 var (
 	decoder = scheme.Codecs.UniversalDeserializer()
 	encoder = runtimejson.NewYAMLSerializer(runtimejson.DefaultMetaFactory, scheme.Scheme, scheme.Scheme)
@@ -820,6 +823,21 @@ will automatically connect to the Apoxy API and begin managing your in-cluster A
 			return err
 		}
 
+		// If --cluster-name wasn't explicitly provided, recover it from the
+		// existing namespace's apoxy.dev/cluster-name annotation so the API
+		// returns YAML consistent with the current install.
+		if clusterName == "" {
+			clientset, err := kubernetes.NewForConfig(kc)
+			if err == nil {
+				ns, err := clientset.CoreV1().Namespaces().Get(cmd.Context(), namespace, metav1.GetOptions{})
+				if err == nil {
+					if v, ok := ns.Annotations[clusterNameAnnotation]; ok {
+						clusterName = v
+					}
+				}
+			}
+		}
+
 		yamlz, err := getYAML(clusterName, mirror)
 		if err != nil {
 			return fmt.Errorf("failed to get YAML: %w", err)