Index: flexoentity/flexo_entity.py
===================================================================
--- flexoentity/flexo_entity.py	(revision 0b4a5e684fe37a10105b2493785d18fb025e9e82)
+++ flexoentity/flexo_entity.py	(revision 12d7663f9411a7c917719918b3cc91ca02739960)
@@ -6,5 +6,5 @@
 from enum import Enum, auto
 from dataclasses import dataclass, field
-from datetime import datetime
+from datetime import datetime, UTC
 from typing import Optional
 from abc import ABC
@@ -93,5 +93,5 @@
     state: EntityState = EntityState.DRAFT
     flexo_id: FlexOID = field(init=False)
-    created_at: datetime = field(default_factory=datetime.utcnow)
+    created_at: datetime = field(default_factory=lambda: datetime.now(UTC))
     updated_at: Optional[datetime] = None
 
@@ -183,5 +183,5 @@
 
         self.state = target_state
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(UTC)
 
     # ───────────────────────────────────────────────────────────────
@@ -200,5 +200,5 @@
         """Increment version number on the ID."""
         self.flexo_id = FlexOID.next_version(self.flexo_id)
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(UTC)
 
     def approve(self):
@@ -219,5 +219,5 @@
             self.flexo_id = new_fid
             self.state = EntityState.APPROVED
-            self.updated_at = datetime.utcnow()
+            self.updated_at = datetime.now(UTC)
             return self
         raise ValueError("Only drafts can be approved")
@@ -243,5 +243,5 @@
         )
         self.state = EntityState.DRAFT
-        self.updated_at = datetime.utcnow()
+        self.updated_at = datetime.now(UTC)
 
     # ───────────────────────────────────────────────────────────────
@@ -254,5 +254,5 @@
         if self._update_fingerprint():
             # mark content changed, but version will only bump on next approval/sign/publish
-            self.updated_at = datetime.utcnow()
+            self.updated_at = datetime.now(UTC)
 
 
Index: flexoentity/id_factory.py
===================================================================
--- flexoentity/id_factory.py	(revision 0b4a5e684fe37a10105b2493785d18fb025e9e82)
+++ flexoentity/id_factory.py	(revision 12d7663f9411a7c917719918b3cc91ca02739960)
@@ -199,4 +199,9 @@
     @property
     def prefix(self) -> str:
+        # nur bis einschließlich Hash-Teil
+        return self.flexo_id.split('@')[0].rsplit('-', 1)[0]
+
+    @property
+    def prefix_old(self) -> str:
         return self.flexo_id.rsplit("@", 1)[0]
     # ──────────────────────────────────────────────────────────────────────────