Preserve defaults-only input absence

docs/roadmap/remediation.md

@@ -191,7 +191,12 @@ named `version`.
 
 ## 6. Preserve absence for ordinary defaults-only loads — P2
 
-- [ ] Addressed and regression-tested.
+- [x] Addressed and regression-tested.
+
+Completion: absent ordinary input stays absent until an existing explicit layer
+needs assembly. Public parity tests cover values, root presence/origin, optional
+registrations/defaults, and real empty mappings. Existing defaults-only override
+coverage and the everyday check passed.
 
 **Owner:** `executeLoadRequest` in
 [load.go](../../internal/engine/load.go), lines 210–216, and

facade_sequence_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
+	"reflect"
 	"strings"
 	"testing"
 	"testing/fstest"
@@ -11,6 +12,45 @@ import (
 	configkit "gitea.maximumdirect.net/eric/ConfigKit"
 )
 
+func TestFacadeNoSourcePreservesAbsenceWithSequencePolicy(t *testing.T) {
+	t.Parallel()
+	for _, defaults := range []bool{false, true} {
+		for _, registered := range []bool{false, true} {
+			definition := configkit.Definition[map[string]any]{}
+			if defaults {
+				definition.Defaults = func() map[string]any { return map[string]any{"fallback": true} }
+			}
+			if registered {
+				definition.SequenceCompositions = []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}
+			}
+			ordinary, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{Definition: definition})
+			if err != nil {
+				t.Fatal(err)
+			}
+			layered, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{Definition: definition})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !reflect.DeepEqual(ordinary.Config, layered.Config) {
+				t.Fatal("NoSource values differ between entry points")
+			}
+			for _, result := range []*configkit.Result[map[string]any]{ordinary, layered} {
+				if len(result.Sources()) != 0 || result.Metadata().IsExplicit(configkit.Keys()) {
+					t.Fatal("NoSource contributed an explicit root")
+				}
+				info, ok := result.Metadata().Lookup(configkit.Keys())
+				if !ok || info.Origin.Layer != configkit.LayerDefault {
+					t.Fatalf("NoSource root origin = %#v, %t", info, ok)
+				}
+			}
+			empty, err := configkit.Load(configkit.Mapping("empty", map[string]any{}), configkit.Options[map[string]any]{Definition: definition})
+			if err != nil || !empty.Metadata().IsExplicit(configkit.Keys()) {
+				t.Fatal("real empty mapping lost its presence")
+			}
+		}
+	}
+}
+
 func TestFacadeItemHelperHistoryPreservesTraversalOrder(t *testing.T) {
 	t.Parallel()
 	filesystem := configkit.NewFilesystem("history", fstest.MapFS{

internal/engine/load.go

@@ -207,7 +207,7 @@ func executeLoadRequest[T any](request loadRequest[T], secrets SecretBinding, lo
 			return nil, accumulator.loadError()
 		}
 	}
-	if request.ordinary {
+	if request.ordinary && input.document != nil {
 		input.composition, diagnostics = compositionForInputWithPolicy(input, request.sequencePolicy)
 		if len(diagnostics) != 0 {
 			accumulator.add(diagnostics...)