fix(config): order feature hooks before image hooks per spec

e2e/tests/up-features/testdata/docker-features-hooks-order/.devcontainer.json

@@ -0,0 +1,8 @@
+{
+  "name": "Feature Hook Order Test",
+  "image": "ghcr.io/devsy-org/test-images/base:ubuntu",
+  "features": {
+    "./.devcontainer/features/test-order": {}
+  },
+  "onCreateCommand": "echo 'image' >> /tmp/hook-order.txt"
+}

e2e/tests/up-features/testdata/docker-features-hooks-order/.devcontainer/features/test-order/devcontainer-feature.json

@@ -0,0 +1,6 @@
+{
+  "id": "test-order",
+  "version": "1.0.0",
+  "name": "Test Hook Order",
+  "onCreateCommand": "echo 'feature' >> /tmp/hook-order.txt"
+}

e2e/tests/up-features/testdata/docker-features-hooks-order/.devcontainer/features/test-order/install.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+echo "test-order feature installed"

e2e/tests/up-features/up_features.go

@@ -52,6 +52,31 @@ var _ = ginkgo.Describe("testing up command", ginkgo.Label("up-features", "suite
 		framework.ExpectEqual(strings.TrimSpace(out), "feature-postStart")
 	}, ginkgo.SpecTimeout(framework.TimeoutShort()))
 
+	ginkgo.It("lifecycle hooks order feature before image", func(ctx context.Context) {
+		f, err := setupDockerProvider(initialDir+"/bin", "docker")
+		framework.ExpectNoError(err)
+
+		tempDir, err := framework.CopyToTempDir(
+			"tests/up-features/testdata/docker-features-hooks-order",
+		)
+		framework.ExpectNoError(err)
+		ginkgo.DeferCleanup(framework.CleanupTempDir, initialDir, tempDir)
+
+		wsName := filepath.Base(tempDir)
+		ginkgo.DeferCleanup(f.DevsyWorkspaceDelete, wsName)
+
+		err = f.DevsyUp(ctx, tempDir)
+		framework.ExpectNoError(err)
+
+		out, err := f.DevsySSH(ctx, wsName, "cat /tmp/hook-order.txt")
+		framework.ExpectNoError(err)
+
+		lines := strings.Split(strings.TrimSpace(out), "\n")
+		gomega.Expect(lines).To(gomega.HaveLen(2))
+		gomega.Expect(lines[0]).To(gomega.Equal("feature"))
+		gomega.Expect(lines[1]).To(gomega.Equal("image"))
+	}, ginkgo.SpecTimeout(framework.TimeoutShort()))
+
 	ginkgo.It("http headers download", func(ctx context.Context) {
 		server := ghttp.NewServer()
 		ginkgo.DeferCleanup(server.Close)

pkg/devcontainer/config/merge.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"maps"
+	"slices"
 	"strconv"
 	"strings"
 	"unicode"
@@ -349,10 +350,10 @@ func mergeLifestyleHooks(
 	m func(entry *ImageMetadata) types.LifecycleHook,
 ) []types.LifecycleHook {
 	var out []types.LifecycleHook
-	for _, entry := range entries {
+	for _, entry := range slices.Backward(entries) {
 		val := m(entry)
 		if len(val) > 0 {
-			out = append(out, m(entry))
+			out = append(out, val)
 		}
 	}
 	return out

pkg/devcontainer/config/merge_test.go

@@ -3,6 +3,8 @@ package config
 import (
 	"slices"
 	"testing"
+
+	"github.com/devsy-org/devsy/pkg/types"
 )
 
 const testPortRange = "3000-3002"
@@ -342,3 +344,141 @@ func TestMergeForwardPorts_InvalidRangeSkipped(t *testing.T) {
 		}
 	}
 }
+
+func TestMergeLifestyleHooks_FeatureBeforeImage(t *testing.T) {
+	featureHook := types.LifecycleHook{"feature-cmd": {"echo feature"}}
+	imageHook := types.LifecycleHook{"image-cmd": {"echo image"}}
+
+	// Simulate reversed entries as passed to mergeLifestyleHooks:
+	// [base_image_entry, feature_entry]
+	entries := []*ImageMetadata{
+		{DevContainerActions: DevContainerActions{OnCreateCommand: imageHook}},
+		{DevContainerActions: DevContainerActions{OnCreateCommand: featureHook}},
+	}
+
+	got := mergeLifestyleHooks(entries, func(e *ImageMetadata) types.LifecycleHook {
+		return e.OnCreateCommand
+	})
+
+	if len(got) != 2 {
+		t.Fatalf("expected 2 hooks, got %d", len(got))
+	}
+	if _, ok := got[0]["feature-cmd"]; !ok {
+		t.Errorf("expected feature hook first, got %v", got[0])
+	}
+	if _, ok := got[1]["image-cmd"]; !ok {
+		t.Errorf("expected image hook second, got %v", got[1])
+	}
+}
+
+func TestMergeLifestyleHooks_AllHookTypes(t *testing.T) {
+	featureHook := types.LifecycleHook{"feat": {"echo feat"}}
+	imageHook := types.LifecycleHook{"img": {"echo img"}}
+
+	entries := []*ImageMetadata{
+		{DevContainerActions: DevContainerActions{
+			OnCreateCommand:      imageHook,
+			UpdateContentCommand: imageHook,
+			PostCreateCommand:    imageHook,
+			PostStartCommand:     imageHook,
+			PostAttachCommand:    imageHook,
+		}},
+		{DevContainerActions: DevContainerActions{
+			OnCreateCommand:      featureHook,
+			UpdateContentCommand: featureHook,
+			PostCreateCommand:    featureHook,
+			PostStartCommand:     featureHook,
+			PostAttachCommand:    featureHook,
+		}},
+	}
+
+	hookExtractors := []struct {
+		name string
+		fn   func(e *ImageMetadata) types.LifecycleHook
+	}{
+		{"onCreateCommand", func(e *ImageMetadata) types.LifecycleHook {
+			return e.OnCreateCommand
+		}},
+		{"updateContentCommand", func(e *ImageMetadata) types.LifecycleHook {
+			return e.UpdateContentCommand
+		}},
+		{"postCreateCommand", func(e *ImageMetadata) types.LifecycleHook {
+			return e.PostCreateCommand
+		}},
+		{"postStartCommand", func(e *ImageMetadata) types.LifecycleHook {
+			return e.PostStartCommand
+		}},
+		{"postAttachCommand", func(e *ImageMetadata) types.LifecycleHook {
+			return e.PostAttachCommand
+		}},
+	}
+
+	for _, tc := range hookExtractors {
+		t.Run(tc.name, func(t *testing.T) {
+			got := mergeLifestyleHooks(entries, tc.fn)
+			if len(got) != 2 {
+				t.Fatalf("expected 2 hooks, got %d", len(got))
+			}
+			if _, ok := got[0]["feat"]; !ok {
+				t.Errorf("expected feature hook first, got %v", got[0])
+			}
+			if _, ok := got[1]["img"]; !ok {
+				t.Errorf("expected image hook second, got %v", got[1])
+			}
+		})
+	}
+}
+
+func TestMergeLifestyleHooks_SkipsEmpty(t *testing.T) {
+	featureHook := types.LifecycleHook{"feat": {"echo feat"}}
+
+	entries := []*ImageMetadata{
+		{},
+		{DevContainerActions: DevContainerActions{OnCreateCommand: featureHook}},
+		{},
+	}
+
+	got := mergeLifestyleHooks(entries, func(e *ImageMetadata) types.LifecycleHook {
+		return e.OnCreateCommand
+	})
+
+	if len(got) != 1 {
+		t.Fatalf("expected 1 hook, got %d", len(got))
+	}
+	if _, ok := got[0]["feat"]; !ok {
+		t.Errorf("expected feature hook, got %v", got[0])
+	}
+}
+
+func TestMergeLifestyleHooks_MultipleFeatures(t *testing.T) {
+	imageHook := types.LifecycleHook{"img": {"echo img"}}
+	feature1Hook := types.LifecycleHook{"feat1": {"echo feat1"}}
+	feature2Hook := types.LifecycleHook{"feat2": {"echo feat2"}}
+
+	// After ReverseSlice in MergeConfiguration, entries are:
+	// [base_image, feature2 (last applied), feature1 (first applied), user_config]
+	// mergeLifestyleHooks iterates in reverse producing:
+	// user_config hooks, feature1 hooks, feature2 hooks, base_image hooks
+	entries := []*ImageMetadata{
+		{DevContainerActions: DevContainerActions{OnCreateCommand: imageHook}},
+		{DevContainerActions: DevContainerActions{OnCreateCommand: feature2Hook}},
+		{DevContainerActions: DevContainerActions{OnCreateCommand: feature1Hook}},
+	}
+
+	got := mergeLifestyleHooks(entries, func(e *ImageMetadata) types.LifecycleHook {
+		return e.OnCreateCommand
+	})
+
+	if len(got) != 3 {
+		t.Fatalf("expected 3 hooks, got %d", len(got))
+	}
+	if _, ok := got[0]["feat1"]; !ok {
+		t.Errorf("expected feature1 hook first, got %v", got[0])
+	}
+	if _, ok := got[1]["feat2"]; !ok {
+		t.Errorf("expected feature2 hook second, got %v", got[1])
+	}
+	if _, ok := got[2]["img"]; !ok {
+		t.Errorf("expected image hook last, got %v", got[2])
+	}
+}