feat: Stabilize ResourceGroup API to v1

- Introduce stable v1 API for ResourceGroup
- Add v1/types.go with stable ResourceGroup type
- Add v1/doc.go with API documentation
- Mark v1alpha1 as deprecated with migration path
- Maintain backward compatibility with v1alpha1
- Follow semantic versioning for API stability

Part of #4450 - API Types Stabilization

Author: NETIZEN-11

pkg/api/resourcegroup/v1/doc.go

@@ -0,0 +1,21 @@
+// Copyright 2026 The kpt Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package v1 contains the stable v1 API for ResourceGroup.
+// This API is stable and follows semantic versioning.
+// Breaking changes will only be introduced in a new major version (v2).
+//
+// +kubebuilder:object:generate=true
+// +groupName=kpt.dev
+package v1

pkg/api/resourcegroup/v1/types.go

@@ -0,0 +1,63 @@
+// Copyright 2021,2026 The kpt Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package v1 defines ResourceGroup schema.
+// Version: v1 (stable)
+// swagger:meta
+package v1
+
+import (
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/cli-utils/pkg/common"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+const (
+	RGFileName = "resourcegroup.yaml"
+	// RGInventoryIDLabel is the label name used for storing an inventory ID.
+	RGInventoryIDLabel = common.InventoryLabel
+
+	// Deprecated: prefer ResourceGroupGVK
+	RGFileKind = "ResourceGroup"
+	// Deprecated: prefer ResourceGroupGVK
+	RGFileGroup = "kpt.dev"
+	// Deprecated: prefer ResourceGroupGVK
+	RGFileVersion = "v1"
+	// Deprecated: prefer ResourceGroupGVK
+	RGFileAPIVersion = RGFileGroup + "/" + RGFileVersion
+)
+
+// ResourceGroupGVK is the GroupVersionKind of ResourceGroup objects
+func ResourceGroupGVK() schema.GroupVersionKind {
+	return schema.GroupVersionKind{
+		Group:   "kpt.dev",
+		Version: "v1",
+		Kind:    "ResourceGroup",
+	}
+}
+
+// DefaultMeta is the ResourceMeta for ResourceGroup instances.
+var DefaultMeta = yaml.ResourceMeta{
+	TypeMeta: yaml.TypeMeta{
+		APIVersion: RGFileAPIVersion,
+		Kind:       RGFileKind,
+	},
+}
+
+// ResourceGroup contains the inventory information about a package managed with kpt.
+// This is the stable v1 API for ResourceGroup.
+// swagger:model resourcegroup
+type ResourceGroup struct {
+	yaml.ResourceMeta `yaml:",inline" json:",inline"`
+}

pkg/api/resourcegroup/v1alpha1/types.go

@@ -12,8 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package defines ResourceGroup schema.
+// Package v1alpha1 defines ResourceGroup schema.
 // Version: v1alpha1
+//
+// Deprecated: v1alpha1 is deprecated. Use github.com/kptdev/kpt/pkg/api/resourcegroup/v1 instead.
+// This package is maintained for backward compatibility only and will be removed in v2.0.0.
 // swagger:meta
 package v1alpha1
 
@@ -39,6 +42,8 @@ const (
 )
 
 // ResourceGroupGVK is the GroupVersionKind of ResourceGroup objects
+//
+// Deprecated: Use github.com/kptdev/kpt/pkg/api/resourcegroup/v1.ResourceGroupGVK instead.
 func ResourceGroupGVK() schema.GroupVersionKind {
 	return schema.GroupVersionKind{
 		Group:   "kpt.dev",