Expose source version modes in load options

layered.go

@@ -23,8 +23,12 @@ type Underlay struct{ Inputs []Input }
 // LayeredOptions selects lower-priority tiers and final application rules.
 // An active Overlay requires an explicit OverlayFilesystem; an inactive overlay
 // ignores it. Overrides remain explicit CLI records, not general mappings.
+// SourceVersionMode applies one declaration policy to main, underlay, import,
+// and selected overlay documents. Enabled modes interpret the version path
+// source-locally while protecting main's destination-prefixed path.
 type LayeredOptions[T any] struct {
 	Definition        Definition[T]
+	SourceVersionMode SourceVersionMode
 	Underlays         []Underlay
 	Overlay           string
 	OverlayFilesystem *FilesystemContext
@@ -57,7 +61,9 @@ func toEngineInput(input Input) engine.Input {
 
 func toEngineLayeredOptions[T any](options LayeredOptions[T]) engine.LayeredOptions[T] {
 	result := engine.LayeredOptions[T]{
-		Definition: toEngineDefinition(options.Definition), Overlay: options.Overlay,
+		Definition:        toEngineDefinition(options.Definition),
+		SourceVersionMode: engine.SourceVersionModeFromFacade(uint8(options.SourceVersionMode)),
+		Overlay:           options.Overlay,
 		OverlayFilesystem: toEngineFilesystemContext(options.OverlayFilesystem),
 	}
 	if options.Underlays != nil {