Derive selected overlay context from the main input

internal/engine/selected_overlay.go

@@ -29,11 +29,12 @@ func validOverlayName(name string) bool {
 }
 
 type selectedOverlayRequest struct {
-	name           string
-	protectionRule *VersionRule
-	sequencePolicy sequencePolicy
-	limits         importLimits
-	versionState   *sourceVersionState
+	name            string
+	lookupDirectory string
+	protectionRule  *VersionRule
+	sequencePolicy  sequencePolicy
+	limits          importLimits
+	versionState    *sourceVersionState
 }
 
 func resolveOrdinaryOverlayFilesystem(source Source, context *FilesystemContext, main parsedSource, existing *resolvedFilesystemContext) (resolvedFilesystemContext, *Diagnostic) {
@@ -70,7 +71,11 @@ func loadSelectedOverlay(request selectedOverlayRequest, access *filesystemAcces
 			_ = access.close()
 		}
 	}()
-	overlayPath := access.join(access.rootPath, "overlays/"+request.name+".yml")
+	lookupDirectory := request.lookupDirectory
+	if lookupDirectory == "" {
+		lookupDirectory = access.rootPath
+	}
+	overlayPath := access.join(lookupDirectory, "overlays/"+request.name+".yml")
 	canonical, err := access.canonical(overlayPath)
 	if err != nil {
 		code := CodeOverlayInvalid