diff --git a/src/ui/mixins/tree_manager.py b/src/ui/mixins/tree_manager.py
index 038fd76..758eacb 100644
--- a/src/ui/mixins/tree_manager.py
+++ b/src/ui/mixins/tree_manager.py
@@ -11,6 +11,7 @@ Dieses Mixin enthält alle Methoden für die Verwaltung des TreeWidgets im MainW
 import logging
 import shutil
 import time
+from enum import Enum, auto
 from pathlib import Path
 
 from PySide6.QtCore import Qt
@@ -31,6 +32,13 @@ from ui.TreeNodeEditDialog import TreeNodeEditDialog
 from ui.XslFileEditDialog import XslFileEditDialog
 
 
+class ItemType(Enum):
+    TREE_NODE = auto()
+    XSL_FILE = auto()
+    XML_FILE = auto()
+    UNKNOWN = auto()
+
+
 logger = logging.getLogger(__name__)
 
 
@@ -68,7 +76,7 @@ class TreeManagerMixin:
 
         if not item:
             # Kein Item gefunden - zeige Kontextmenü für Root-Elemente
-            node_type = "Unknown"
+            node_type = ItemType.UNKNOWN
             context_menu = self._create_context_menu_for_type(node_type, None)
         else:
             # Bestimme den Node-Typ basierend auf dem Item
@@ -109,7 +117,7 @@ class TreeManagerMixin:
             node_type = self._get_node_type_from_item(item)
             logger.debug(f"Selektierter Node-Typ: {node_type}")
 
-            if node_type == "XmlFile":
+            if node_type == ItemType.XML_FILE:
                 # Hole XmlFile-Objekt und XSL-ID aus UserRole
                 xml_file_obj = item.data(0, Qt.ItemDataRole.UserRole)
                 xsl_id_str = item.data(1, Qt.ItemDataRole.UserRole)
@@ -165,13 +173,13 @@ class TreeManagerMixin:
                 # Child-Item - prüfe ob es ein XML-File ist
                 text = item.text(0)
                 if text.startswith("XML:"):
-                    return "XmlFile"
+                    return ItemType.XML_FILE
                 else:
                     # Könnte ein TreeNode-Child oder XslFile-Child sein
                     # Prüfe den Parent-Typ
                     parent_type = self._get_node_type_from_item(parent_item)
-                    if parent_type == "XslFile":
-                        return "XmlFile"
+                    if parent_type == ItemType.XSL_FILE:
+                        return ItemType.XML_FILE
                     else:
                         # Rekursiv bestimmen basierend auf gespeicherten Daten
                         return self._determine_node_type_from_data(item)
@@ -181,7 +189,7 @@ class TreeManagerMixin:
 
         except Exception as e:
             logger.error(f"Fehler beim Bestimmen des Node-Typs: {e}")
-            return "Unknown"
+            return ItemType.UNKNOWN
 
     def _determine_node_type_from_data(self, item):
         """
@@ -197,21 +205,21 @@ class TreeManagerMixin:
             # Hole das gespeicherte Node-Objekt direkt
             node = item.data(0, Qt.ItemDataRole.UserRole)
             if not node:
-                return "Unknown"
+                return ItemType.UNKNOWN
 
             # Bestimme den Typ direkt vom Node-Objekt
             if isinstance(node, TreeNode):
-                return "TreeNode"
+                return ItemType.TREE_NODE
             elif isinstance(node, XslFile):
-                return "XslFile"
+                return ItemType.XSL_FILE
             elif isinstance(node, XmlFile):
-                return "XmlFile"
+                return ItemType.XML_FILE
 
-            return "Unknown"
+            return ItemType.UNKNOWN
 
         except Exception as e:
             logger.error(f"Fehler beim Bestimmen des Node-Typs aus Daten: {e}")
-            return "Unknown"
+            return ItemType.UNKNOWN
 
     def _find_item_by_node(self, node_obj):
         """
@@ -284,7 +292,7 @@ class TreeManagerMixin:
         try:
             menu = QMenu(self)
 
-            if node_type == "TreeNode":
+            if node_type == ItemType.TREE_NODE:
                 # Kontextmenü für TreeNode
                 action_add_child = QAction("Unterknoten hinzufügen", self)
                 action_add_child.setIcon(QIcon(QIcon.fromTheme("folder-new")))
@@ -338,7 +346,7 @@ class TreeManagerMixin:
                 action_delete.triggered.connect(lambda: self._delete_tree_node(item))
                 menu.addAction(action_delete)
 
-            elif node_type == "XslFile":
+            elif node_type == ItemType.XSL_FILE:
                 # Kontextmenü für XslFile
                 action_add_xml = QAction("XML-Datei hinzufügen", self)
                 action_add_xml.setIcon(QIcon(QIcon.fromTheme("document-new")))
@@ -387,7 +395,7 @@ class TreeManagerMixin:
                 action_delete.triggered.connect(lambda: self._delete_xsl_file(item))
                 menu.addAction(action_delete)
 
-            elif node_type == "XmlFile":
+            elif node_type == ItemType.XML_FILE:
                 # Kontextmenü für XmlFile
                 # Transformations-Aktionen
                 action_transform = QAction("Transformieren", self)