Preserve secret tags in dynamic configuration values

internal/document/document.go

@@ -32,11 +32,14 @@ type Entry struct {
 // Node is ConfigKit's owned configuration representation. Number Text retains its
 // exact validated decimal spelling; Boolean Text is "true" or "false".
 type Node struct {
-	Kind     Kind
-	Location Location
-	Text     string
-	Mapping  []Entry
-	Sequence []*Node
+	// Sensitive preserves field classification from concrete typed projections.
+	// It is metadata, not part of the configuration value or emitted YAML.
+	Sensitive bool
+	Kind      Kind
+	Location  Location
+	Text      string
+	Mapping   []Entry
+	Sequence  []*Node
 }
 
 // Clone returns a detached copy of a node tree.