Explain defaults restored during final decoding

explain.go

@@ -117,6 +117,22 @@ func (r *Result[T]) Explain(path Path) (Explanation, bool) {
 		})
 	}
 
+	// Intermediate input replacements do not permanently suppress defaults:
+	// decoding applies them to the final input tree. Show that reconciliation
+	// explicitly, including canonical scalar conversions, before domain changes.
+	replayed, _ := documentAtPath(working, path)
+	decoded, _ := documentAtPath(r.input, path)
+	if !documentNodesEqual(replayed, decoded) {
+		origin := cloneOrigin(r.inputOrigins[path.String()])
+		origin.Operation = ChangeDecoding
+		explanation.History = append(explanation.History, ValueChange{
+			Before:  valueSnapshot(working, path, r.secrets),
+			After:   valueSnapshot(r.input, path, r.secrets),
+			Origin:  origin,
+			Reasons: []string{"applied retained defaults and canonical typed decoding"},
+		})
+	}
+
 	working = document.Clone(r.input)
 	for _, snapshot := range r.resolution {
 		relevant := pathsIntersect(snapshot.change.Path, path)
@@ -422,7 +438,9 @@ func (r *Result[T]) WriteExplanation(output io.Writer, path Path) error {
 	rendered.WriteString("history:\n")
 	for _, change := range explanation.History {
 		rendered.WriteString("  - representation: ")
-		if change.Origin.Layer == LayerBase || change.Origin.Layer == LayerProfile || change.Origin.Layer == LayerCLI {
+		if change.Origin.Operation == ChangeDecoding {
+			rendered.WriteString("input to canonical typed\n")
+		} else if change.Origin.Layer == LayerBase || change.Origin.Layer == LayerProfile || change.Origin.Layer == LayerCLI {
 			rendered.WriteString("policy-validated input\n")
 		} else {
 			rendered.WriteString("canonical typed\n")