fix: loaded XRD must honor the composite schema

cmd/crossplane/render/xr/cmd.go

@@ -31,6 +31,7 @@ import (
 	"github.com/spf13/afero"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	kruntime "k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/serializer/json"
 	"k8s.io/kube-openapi/pkg/spec3"
 
@@ -166,6 +167,7 @@ func (c *Cmd) Run(k *kong.Context, log logging.Logger, sp terminal.SpinnerPrinte
 		return errors.Wrap(err, "cannot apply function annotation overrides")
 	}
 
+	var xrdUnstructured *unstructured.Unstructured
 	if c.XRD != "" {
 		xrd, err := render.LoadXRD(c.fs, c.XRD)
 		if err != nil {
@@ -175,6 +177,12 @@ func (c *Cmd) Run(k *kong.Context, log logging.Logger, sp terminal.SpinnerPrinte
 		if err := xrpkg.ApplyXRDDefaults(xr.GetUnstructured(), xrd); err != nil {
 			return errors.Wrapf(err, "cannot apply XRD defaults to XR %q", xr.GetName())
 		}
+
+		obj, err := kruntime.DefaultUnstructuredConverter.ToUnstructured(xrd)
+		if err != nil {
+			return errors.Wrapf(err, "cannot convert XRD %q to unstructured", xrd.GetName())
+		}
+		xrdUnstructured = &unstructured.Unstructured{Object: obj}
 	}
 
 	fcreds := []corev1.Secret{}
@@ -283,6 +291,7 @@ func (c *Cmd) Run(k *kong.Context, log logging.Logger, sp terminal.SpinnerPrinte
 		RequiredResources:   rrs,
 		RequiredSchemas:     rsc,
 		FunctionCredentials: fcreds,
+		XRD:                 xrdUnstructured,
 	}
 	req, err := render.BuildCompositeRequest(in)
 	if err != nil {

cmd/crossplane/render/xr/cmd_test.go

@@ -78,6 +78,9 @@ var includeFunctionResultsOutput string
 //go:embed testdata/cmd/output/include-full-xr.yaml
 var includeFullXROutput string
 
+//go:embed testdata/cmd/xrd.yaml
+var xrdYAML string
+
 func newEngineFunc(engine render.Engine) func(*render.EngineFlags, logging.Logger) render.Engine {
 	return func(*render.EngineFlags, logging.Logger) render.Engine {
 		return engine
@@ -470,6 +473,49 @@ func TestCmdRun(t *testing.T) {
 			},
 			want: want{err: cmpopts.AnyError},
 		},
+		"XRDPassedToEngine": {
+			reason: "When --xrd is set, the XRD should be forwarded to the render engine so it can determine the composite schema (Legacy vs Modern).",
+			args: args{
+				cmd: Cmd{
+					CompositeResource: "xr.yaml",
+					Composition:       "composition.yaml",
+					Functions:         "functions.yaml",
+					XRD:               "xrd.yaml",
+					Timeout:           time.Minute,
+					fs:                newTestFS(map[string]string{"xrd.yaml": xrdYAML}),
+					newEngine: newEngineFunc(&render.MockEngine{
+						MockRender: func(_ context.Context, req *renderv1alpha1.RenderRequest) (*renderv1alpha1.RenderResponse, error) {
+							if req.GetComposite().GetCompositeResourceDefinition() == nil {
+								t.Error("expected render request to contain the XRD, got nil")
+							}
+							return &renderv1alpha1.RenderResponse{
+								Output: &renderv1alpha1.RenderResponse_Composite{
+									Composite: &renderv1alpha1.CompositeOutput{
+										CompositeResource: fillResourceRefs(t, req.GetComposite().GetCompositeResource()),
+										ComposedResources: []*structpb.Struct{
+											mustNewStruct(t, map[string]any{
+												"apiVersion": "example.org/v1alpha1",
+												"kind":       "ComposedResource",
+												"metadata": map[string]any{
+													"name": "composed-foo",
+													"annotations": map[string]any{
+														"crossplane.io/composition-resource-name": "composed-foo",
+													},
+												},
+												"spec": map[string]any{"coolField": "composed!"},
+											}),
+										},
+									},
+								},
+							}, nil
+						},
+					}),
+				},
+			},
+			want: want{
+				stdout: successOutput,
+			},
+		},
 		"IncludeFullXR": {
 			reason: "With --include-full-xr, the rendered XR is merged into the input XR so the input's spec.fromXR survives alongside any updated fields.",
 			args: args{

cmd/crossplane/render/xr/testdata/cmd/xrd.yaml

@@ -0,0 +1,22 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: CompositeResourceDefinition
+metadata:
+  name: xnopresources.nop.example.org
+spec:
+  group: nop.example.org
+  names:
+    kind: XNopResource
+    plural: xnopresources
+  versions:
+    - name: v1alpha1
+      served: true
+      referenceable: true
+      schema:
+        openAPIV3Schema:
+          type: object
+          properties:
+            spec:
+              type: object
+              properties:
+                coolField:
+                  type: string