Fix incorrect metadata patch generation

When annotations and labels were missing on the cluster object but
present on the desired object, drift detection produced an "add
/metadata" patch. JSON Patch interprets this as replacing the entire
metadata block, dropping fields like metadata.name.

This update preserves metadata.name in copyAnnotationsAndLabels and
emits separate add operations for annotations and labels. A test
verifies the correct behavior.

Signed-off-by: Yasin Özel <yozel@nebius.com>

Author: yozel

ssa/jsondiff/testdata/annotated-configmap.yaml

@@ -0,0 +1,7 @@
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: "configmap-data"
+  annotations:
+    prev: some-previous-value

ssa/jsondiff/unstructured.go

@@ -246,6 +246,14 @@ func copyAnnotationsAndLabels(obj *unstructured.Unstructured) *unstructured.Unst
 		Object: make(map[string]interface{}),
 	}
 
+	// When annotations and labels were missing on the cluster object but present on the desired object, drift
+	//	detection produced an "add /metadata" patch. JSON Patch interprets this as replacing the entire metadata block,
+	//	dropping fields like metadata.name. By copying name, we preserve at least one field in metadata to avoid this.
+	name, ok, _ := unstructured.NestedFieldCopy(obj.Object, "metadata", "name")
+	if ok {
+		_ = unstructured.SetNestedField(c.Object, name, "metadata", "name")
+	}
+
 	annotations, ok, _ := unstructured.NestedFieldCopy(obj.Object, "metadata", "annotations")
 	if ok {
 		_ = unstructured.SetNestedField(c.Object, annotations, "metadata", "annotations")

ssa/jsondiff/unstructured_test.go

@@ -94,10 +94,8 @@ func TestUnstructuredList(t *testing.T) {
 						DesiredObject: desired[1],
 						ClusterObject: cluster[1],
 						Patch: jsondiff.Patch{
-							{Type: jsondiff.OperationAdd, Path: "/metadata", Value: map[string]interface{}{
-								"annotations": map[string]interface{}{
-									"annotated": "yes",
-								},
+							{Type: jsondiff.OperationAdd, Path: "/metadata/annotations", Value: map[string]interface{}{
+								"annotated": "yes",
 							}},
 						},
 					},
@@ -250,10 +248,8 @@ func TestUnstructuredList(t *testing.T) {
 						DesiredObject: desired[1],
 						ClusterObject: cluster[1],
 						Patch: jsondiff.Patch{
-							{Type: jsondiff.OperationAdd, Path: "/metadata", Value: map[string]interface{}{
-								"labels": map[string]interface{}{
-									"labeled": "change",
-								},
+							{Type: jsondiff.OperationAdd, Path: "/metadata/labels", Value: map[string]interface{}{
+								"labeled": "change",
 							}},
 						},
 					},
@@ -294,10 +290,8 @@ func TestUnstructuredList(t *testing.T) {
 						DesiredObject: desired[1],
 						ClusterObject: cluster[1],
 						Patch: jsondiff.Patch{
-							{Type: jsondiff.OperationAdd, Path: "/metadata", Value: map[string]interface{}{
-								"labels": map[string]interface{}{
-									"labeled": "change",
-								},
+							{Type: jsondiff.OperationAdd, Path: "/metadata/labels", Value: map[string]interface{}{
+								"labeled": "change",
 							}},
 						},
 					},
@@ -507,6 +501,44 @@ func TestUnstructured(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "ConfigMap with added label and annotation",
+			path: "testdata/empty-configmap.yaml",
+			mutateDesired: func(obj *unstructured.Unstructured) {
+				_ = unstructured.SetNestedField(obj.Object, "yes", "metadata", "annotations", "annotated")
+				_ = unstructured.SetNestedField(obj.Object, "yes", "metadata", "labels", "labeled")
+			},
+			want: func(desired, cluster client.Object) *Diff {
+				return &Diff{
+					Type:          DiffTypeUpdate,
+					DesiredObject: desired,
+					ClusterObject: cluster,
+					Patch: jsondiff.Patch{
+						{Type: jsondiff.OperationAdd, Path: "/metadata/annotations", Value: map[string]interface{}{"annotated": "yes"}},
+						{Type: jsondiff.OperationAdd, Path: "/metadata/labels", Value: map[string]interface{}{"labeled": "yes"}},
+					},
+				}
+			},
+		},
+		{
+			name: "Annotated ConfigMap with added label and annotation",
+			path: "testdata/annotated-configmap.yaml",
+			mutateDesired: func(obj *unstructured.Unstructured) {
+				_ = unstructured.SetNestedField(obj.Object, "yes", "metadata", "annotations", "annotated")
+				_ = unstructured.SetNestedField(obj.Object, "yes", "metadata", "labels", "labeled")
+			},
+			want: func(desired, cluster client.Object) *Diff {
+				return &Diff{
+					Type:          DiffTypeUpdate,
+					DesiredObject: desired,
+					ClusterObject: cluster,
+					Patch: jsondiff.Patch{
+						{Type: jsondiff.OperationAdd, Path: "/metadata/annotations/annotated", Value: "yes"},
+						{Type: jsondiff.OperationAdd, Path: "/metadata/labels", Value: map[string]interface{}{"labeled": "yes"}},
+					},
+				}
+			},
+		},
 		{
 			name: "Deployment with missing label and annotation",
 			path: "testdata/deployment.yaml",