feat(action): implement ordered subchart install for HIP-0025

- Add performOrderedInstall to deploy resources in DAG batch order
- Add SplitManifestsBySubchart to partition manifests by subchart source
- Add BuildInstallBatches to compute ordered deployment batches from chart metadata
- Extract createAndWaitResources helper for reuse across install paths
- When --wait=ordered, install hooks normally but deploy resources per subchart DAG
- Falls back to standard all-at-once deploy when no sequencing metadata exists
- 7 unit tests for manifest splitting and batch construction

pkg/action/install.go

@@ -492,15 +492,134 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 		}
 	}
 
-	// At this point, we can do the install. Note that before we were detecting whether to
-	// do an update, but it's not clear whether we WANT to do an update if the reuse is set
-	// to true, since that is basically an upgrade operation.
+	// HIP-0025: ordered sequencing — deploy resources in subchart dependency order
+	if i.WaitStrategy == kube.OrderedStrategy {
+		if err := i.performOrderedInstall(rel, toBeAdopted, resources); err != nil {
+			return rel, err
+		}
+	} else {
+		// Default: install all resources at once
+		if len(toBeAdopted) == 0 && len(resources) > 0 {
+			_, err = i.cfg.KubeClient.Create(
+				resources,
+				kube.ClientCreateOptionServerSideApply(i.ServerSideApply, false))
+		} else if len(resources) > 0 {
+			updateThreeWayMergeForUnstructured := i.TakeOwnership && !i.ServerSideApply
+			_, err = i.cfg.KubeClient.Update(
+				toBeAdopted,
+				resources,
+				kube.ClientUpdateOptionForceReplace(i.ForceReplace),
+				kube.ClientUpdateOptionServerSideApply(i.ServerSideApply, i.ForceConflicts),
+				kube.ClientUpdateOptionThreeWayMergeForUnstructured(updateThreeWayMergeForUnstructured),
+				kube.ClientUpdateOptionUpgradeClientSideFieldManager(true))
+		}
+		if err != nil {
+			return rel, err
+		}
+
+		var waiter kube.Waiter
+		if c, supportsOptions := i.cfg.KubeClient.(kube.InterfaceWaitOptions); supportsOptions {
+			waiter, err = c.GetWaiterWithOptions(i.WaitStrategy, i.WaitOptions...)
+		} else {
+			waiter, err = i.cfg.KubeClient.GetWaiter(i.WaitStrategy)
+		}
+		if err != nil {
+			return rel, fmt.Errorf("failed to get waiter: %w", err)
+		}
+
+		if i.WaitForJobs {
+			err = waiter.WaitWithJobs(resources, i.Timeout)
+		} else {
+			err = waiter.Wait(resources, i.Timeout)
+		}
+		if err != nil {
+			return rel, err
+		}
+	}
+
+	if !i.DisableHooks {
+		if err := i.cfg.execHook(rel, release.HookPostInstall, i.WaitStrategy, i.WaitOptions, i.Timeout, i.ServerSideApply); err != nil {
+			return rel, fmt.Errorf("failed post-install: %s", err)
+		}
+	}
+
+	if len(i.Description) > 0 {
+		rel.SetStatus(rcommon.StatusDeployed, i.Description)
+	} else {
+		rel.SetStatus(rcommon.StatusDeployed, "Install complete")
+	}
+
+	if err := i.recordRelease(rel); err != nil {
+		i.cfg.Logger().Error("failed to record the release", slog.Any("error", err))
+	}
+
+	return rel, nil
+}
+
+// performOrderedInstall deploys resources in subchart dependency order as defined
+// by HIP-0025. Resources are grouped by subchart, then deployed in batches
+// according to the subchart DAG. Each batch is deployed and waited for before
+// the next batch begins.
+func (i *Install) performOrderedInstall(rel *release.Release, toBeAdopted kube.ResourceList, resources kube.ResourceList) error {
+	batches, err := BuildInstallBatches(rel.Chart)
+	if err != nil {
+		return fmt.Errorf("failed to build installation order: %w", err)
+	}
+
+	// If no sequencing declared, fall back to deploying all at once
+	if batches == nil {
+		return i.createAndWaitResources(toBeAdopted, resources)
+	}
+
+	// Split the manifest by subchart
+	subchartManifests := SplitManifestsBySubchart(rel.Manifest, rel.Chart.Metadata.Name)
+
+	i.cfg.Logger().Info(fmt.Sprintf("ordered install: %d batches to deploy", len(batches)))
+
+	for batchIdx, batch := range batches {
+		i.cfg.Logger().Info(fmt.Sprintf("deploying batch %d: %v", batchIdx+1, batch))
+
+		// Collect manifests for this batch
+		var batchManifest string
+		for _, subchartName := range batch {
+			if m, ok := subchartManifests[subchartName]; ok {
+				if batchManifest != "" {
+					batchManifest += "\n---\n"
+				}
+				batchManifest += m
+			}
+		}
+
+		if batchManifest == "" {
+			continue
+		}
+
+		// Build resource list from batch manifest
+		batchResources, err := i.cfg.KubeClient.Build(
+			bytes.NewBufferString(batchManifest),
+			!i.DisableOpenAPIValidation,
+		)
+		if err != nil {
+			return fmt.Errorf("failed to build resources for batch %d: %w", batchIdx+1, err)
+		}
+
+		if err := i.createAndWaitResources(nil, batchResources); err != nil {
+			return fmt.Errorf("batch %d (%v) failed: %w", batchIdx+1, batch, err)
+		}
+	}
+
+	return nil
+}
+
+// createAndWaitResources creates resources and waits for readiness.
+func (i *Install) createAndWaitResources(toBeAdopted kube.ResourceList, resources kube.ResourceList) error {
+	var err error
 	if len(toBeAdopted) == 0 && len(resources) > 0 {
 		_, err = i.cfg.KubeClient.Create(
 			resources,
 			kube.ClientCreateOptionServerSideApply(i.ServerSideApply, false))
 	} else if len(resources) > 0 {
-		updateThreeWayMergeForUnstructured := i.TakeOwnership && !i.ServerSideApply // Use three-way merge when taking ownership (and not using server-side apply)
+		updateThreeWayMergeForUnstructured := i.TakeOwnership && !i.ServerSideApply
 		_, err = i.cfg.KubeClient.Update(
 			toBeAdopted,
 			resources,
@@ -510,7 +629,7 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 			kube.ClientUpdateOptionUpgradeClientSideFieldManager(true))
 	}
 	if err != nil {
-		return rel, err
+		return err
 	}
 
 	var waiter kube.Waiter
@@ -520,7 +639,7 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 		waiter, err = i.cfg.KubeClient.GetWaiter(i.WaitStrategy)
 	}
 	if err != nil {
-		return rel, fmt.Errorf("failed to get waiter: %w", err)
+		return fmt.Errorf("failed to get waiter: %w", err)
 	}
 
 	if i.WaitForJobs {
@@ -528,34 +647,7 @@ func (i *Install) performInstall(rel *release.Release, toBeAdopted kube.Resource
 	} else {
 		err = waiter.Wait(resources, i.Timeout)
 	}
-	if err != nil {
-		return rel, err
-	}
-
-	if !i.DisableHooks {
-		if err := i.cfg.execHook(rel, release.HookPostInstall, i.WaitStrategy, i.WaitOptions, i.Timeout, i.ServerSideApply); err != nil {
-			return rel, fmt.Errorf("failed post-install: %s", err)
-		}
-	}
-
-	if len(i.Description) > 0 {
-		rel.SetStatus(rcommon.StatusDeployed, i.Description)
-	} else {
-		rel.SetStatus(rcommon.StatusDeployed, "Install complete")
-	}
-
-	// This is a tricky case. The release has been created, but the result
-	// cannot be recorded. The truest thing to tell the user is that the
-	// release was created. However, the user will not be able to do anything
-	// further with this release.
-	//
-	// One possible strategy would be to do a timed retry to see if we can get
-	// this stored in the future.
-	if err := i.recordRelease(rel); err != nil {
-		i.cfg.Logger().Error("failed to record the release", slog.Any("error", err))
-	}
-
-	return rel, nil
+	return err
 }
 
 func (i *Install) failRelease(rel *release.Release, err error) (*release.Release, error) {

pkg/action/sequencing.go

@@ -0,0 +1,124 @@
+/*
+Copyright The Helm 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 action
+
+import (
+	"fmt"
+	"strings"
+
+	chart "helm.sh/helm/v4/pkg/chart/v2"
+	chartutil "helm.sh/helm/v4/pkg/chart/v2/util"
+)
+
+// SubchartManifests groups rendered manifest content by subchart name.
+// The parent chart's own resources are keyed by the chart name itself.
+type SubchartManifests map[string]string
+
+// SplitManifestsBySubchart splits a rendered manifest string into per-subchart
+// manifest strings based on the # Source: comments that Helm inserts during rendering.
+//
+// Each manifest document is attributed to a subchart by parsing the Source path:
+//   - "parentchart/templates/foo.yaml" → parent chart
+//   - "parentchart/charts/subchart/templates/bar.yaml" → "subchart"
+//   - "parentchart/charts/sub1/charts/sub2/templates/baz.yaml" → "sub1" (immediate child)
+//
+// The chartName parameter is the root chart name used to identify parent resources.
+func SplitManifestsBySubchart(manifest string, chartName string) SubchartManifests {
+	result := make(SubchartManifests)
+
+	// Split on YAML document separator
+	docs := strings.Split(manifest, "---")
+	for _, doc := range docs {
+		doc = strings.TrimSpace(doc)
+		if doc == "" {
+			continue
+		}
+
+		owner := chartName // default: parent chart owns this resource
+		// Look for # Source: comment to determine subchart
+		for line := range strings.SplitSeq(doc, "\n") {
+			trimmed := strings.TrimSpace(line)
+			if sourcePath, ok := strings.CutPrefix(trimmed, "# Source: "); ok {
+				owner = subchartFromSourcePath(sourcePath, chartName)
+				break
+			}
+		}
+
+		if existing, ok := result[owner]; ok {
+			result[owner] = existing + "\n---\n" + doc
+		} else {
+			result[owner] = doc
+		}
+	}
+
+	return result
+}
+
+// subchartFromSourcePath extracts the immediate subchart name from a Source path.
+// Path format: "chartname/charts/subchartname/templates/file.yaml"
+// or: "chartname/templates/file.yaml" (parent chart)
+func subchartFromSourcePath(sourcePath, chartName string) string {
+	parts := strings.Split(sourcePath, "/")
+	// Find "charts" segment — the next segment is the subchart name
+	for i, part := range parts {
+		if part == "charts" && i+1 < len(parts) {
+			return parts[i+1]
+		}
+	}
+	// No "charts" segment → belongs to parent chart
+	return chartName
+}
+
+// BuildInstallBatches constructs ordered batches of subchart names for installation.
+// Returns batches where each batch can be installed in parallel, and batches
+// are processed sequentially. The parent chart name is always in the last batch.
+//
+// If the chart has no sequencing metadata, returns nil (all resources deployed at once).
+func BuildInstallBatches(chrt *chart.Chart) ([][]string, error) {
+	if chrt.Metadata == nil {
+		return nil, nil
+	}
+
+	// Check if any sequencing declarations exist
+	hasAnnotation := false
+	if chrt.Metadata.Annotations != nil {
+		_, hasAnnotation = chrt.Metadata.Annotations[chartutil.AnnotationDependsOnSubcharts]
+	}
+
+	hasDependsOn := false
+	for _, dep := range chrt.Metadata.Dependencies {
+		if len(dep.DependsOn) > 0 {
+			hasDependsOn = true
+			break
+		}
+	}
+
+	if !hasAnnotation && !hasDependsOn {
+		return nil, nil
+	}
+
+	dag, err := chartutil.BuildSubchartDAG(chrt)
+	if err != nil {
+		return nil, fmt.Errorf("failed to build subchart dependency graph: %w", err)
+	}
+
+	batches, err := dag.Batches()
+	if err != nil {
+		return nil, fmt.Errorf("failed to compute installation order: %w", err)
+	}
+
+	return batches, nil
+}

pkg/action/sequencing_test.go

@@ -0,0 +1,162 @@
+/*
+Copyright The Helm 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 action
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	chart "helm.sh/helm/v4/pkg/chart/v2"
+	chartutil "helm.sh/helm/v4/pkg/chart/v2/util"
+)
+
+func TestSplitManifestsBySubchart(t *testing.T) {
+	manifest := `---
+# Source: myapp/templates/service.yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: myapp-svc
+---
+# Source: myapp/charts/redis/templates/deployment.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: redis
+---
+# Source: myapp/charts/redis/templates/service.yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: redis-svc
+---
+# Source: myapp/charts/nginx/templates/deployment.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx`
+
+	result := SplitManifestsBySubchart(manifest, "myapp")
+
+	assert.Len(t, result, 3)
+	assert.Contains(t, result, "myapp")
+	assert.Contains(t, result, "redis")
+	assert.Contains(t, result, "nginx")
+
+	// Parent chart has 1 resource
+	assert.Contains(t, result["myapp"], "myapp-svc")
+
+	// Redis has 2 resources
+	assert.Contains(t, result["redis"], "redis")
+	assert.Contains(t, result["redis"], "redis-svc")
+
+	// Nginx has 1 resource
+	assert.Contains(t, result["nginx"], "nginx")
+}
+
+func TestSplitManifestsBySubchartNested(t *testing.T) {
+	manifest := `---
+# Source: parent/charts/redis/charts/sentinel/templates/deploy.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: sentinel`
+
+	result := SplitManifestsBySubchart(manifest, "parent")
+
+	// Nested subchart sentinel under redis → immediate child is "redis"
+	assert.Contains(t, result, "redis")
+	assert.Contains(t, result["redis"], "sentinel")
+}
+
+func TestSplitManifestsBySubchartEmpty(t *testing.T) {
+	result := SplitManifestsBySubchart("", "myapp")
+	assert.Empty(t, result)
+}
+
+func TestSplitManifestsBySubchartNoSource(t *testing.T) {
+	manifest := `---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: orphan`
+
+	result := SplitManifestsBySubchart(manifest, "myapp")
+
+	// No Source comment → attributed to parent
+	assert.Contains(t, result, "myapp")
+	assert.Contains(t, result["myapp"], "orphan")
+}
+
+func TestBuildInstallBatchesNoSequencing(t *testing.T) {
+	chrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "myapp",
+			Dependencies: []*chart.Dependency{
+				{Name: "redis"},
+				{Name: "nginx"},
+			},
+		},
+	}
+
+	batches, err := BuildInstallBatches(chrt)
+	require.NoError(t, err)
+	assert.Nil(t, batches, "no batches when no sequencing declared")
+}
+
+func TestBuildInstallBatchesWithDependsOn(t *testing.T) {
+	chrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "foo",
+			Annotations: map[string]string{
+				chartutil.AnnotationDependsOnSubcharts: `["bar", "rabbitmq"]`,
+			},
+			Dependencies: []*chart.Dependency{
+				{Name: "nginx"},
+				{Name: "rabbitmq"},
+				{
+					Name:      "bar",
+					DependsOn: []string{"nginx", "rabbitmq"},
+				},
+			},
+		},
+	}
+
+	batches, err := BuildInstallBatches(chrt)
+	require.NoError(t, err)
+	require.Len(t, batches, 3)
+	assert.Equal(t, []string{"nginx", "rabbitmq"}, batches[0])
+	assert.Equal(t, []string{"bar"}, batches[1])
+	assert.Equal(t, []string{"foo"}, batches[2])
+}
+
+func TestBuildInstallBatchesCircularDep(t *testing.T) {
+	chrt := &chart.Chart{
+		Metadata: &chart.Metadata{
+			Name: "parent",
+			Dependencies: []*chart.Dependency{
+				{Name: "A", DependsOn: []string{"B"}},
+				{Name: "B", DependsOn: []string{"A"}},
+			},
+		},
+	}
+
+	_, err := BuildInstallBatches(chrt)
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "circular dependency")
+}