diff --git a/DistUpgrade/DistUpgradeQuirks.py b/DistUpgrade/DistUpgradeQuirks.py
index 4c599207..2c3fd680 100644
--- a/DistUpgrade/DistUpgradeQuirks.py
+++ b/DistUpgrade/DistUpgradeQuirks.py
@@ -202,6 +202,41 @@ class DistUpgradeQuirks(object):
     # --- MTA hard-block config (postfix only, temporary during upgrade) ---
     MTA_BLOCK_PREF = "/etc/apt/preferences.d/zz-urug-block-mta-postfix.pref"
 
+    def _resolver(self):
+        # use only one ProblemResolver per stage
+        if not hasattr(self, "__resolver") or self.__resolver is None:
+            try:
+                import apt
+                self.__resolver = apt.ProblemResolver(self._get_cache())
+            except Exception:
+                self.__resolver = None
+        return self.__resolver
+
+    def _apt_mark_install(self, name, protect=False, auto_fix=True, from_user=True):
+        cache = self._get_cache()
+        if cache and name in cache and getattr(cache[name], "candidate", None):
+            try:
+                cache[name].mark_install(from_user=from_user, auto_fix=auto_fix)
+                if protect and self._resolver():
+                    try: self._resolver().protect(cache[name])
+                    except Exception: pass
+                return True
+            except Exception:
+                return False
+        return False
+
+    def _apt_mark_delete(self, name, purge=False):
+        cache = self._get_cache()
+        if cache and name in cache:
+            pkg = cache[name]
+            if getattr(pkg, "is_installed", False) or getattr(pkg, "marked_install", False):
+                try:
+                    pkg.mark_delete(auto_fix=False)
+                    return True
+                except Exception:
+                    return False
+        return False
+
     def PreDistUpgradeCache(self):
         """ run right before calculating the dist-upgrade """
         logging.debug("running Quirks.PreDistUpgradeCache")