diff --git a/utils.py b/utils.py
index 52eca86..0fc2b6e 100644
--- a/utils.py
+++ b/utils.py
@@ -16,6 +16,37 @@ def silence_puresky():
     return removed
 
 
+def _snapshot_fragile_sockets(obj, mod, iface):
+    """Snapshot Material/Object sockets before modifying any override.
+
+    Writing to ANY mod[sid] on a GeoNode modifier can trigger Blender
+    to re-evaluate ALL library overrides on that modifier, wiping
+    Material and Object sockets back to their library defaults (NONE).
+    """
+    FRAGILE_TYPES = {'NodeSocketMaterial', 'NodeSocketObject'}
+    snapshot = {}
+    for item in iface.items_tree:
+        if item.item_type != 'SOCKET' or item.in_out != 'INPUT':
+            continue
+        if item.socket_type not in FRAGILE_TYPES:
+            continue
+        sid = item.identifier
+        if sid in mod and mod[sid] is not None:
+            snapshot[sid] = mod[sid]
+    return snapshot
+
+
+def _restore_fragile_sockets(mod, snapshot):
+    """Restore Material/Object sockets that got wiped by override re-eval."""
+    restored = 0
+    for sid, value in snapshot.items():
+        current = mod[sid] if sid in mod else None
+        if current is None and value is not None:
+            mod[sid] = value
+            restored += 1
+    return restored
+
+
 def fix_lib_overrides():
     fixed = 0
     for obj in bpy.data.objects:
@@ -28,14 +59,19 @@ def fix_lib_overrides():
                 continue
 
             ng = mod.node_group
-            name_to_sid = {}
             iface = getattr(ng, 'interface', None)
-            if iface and hasattr(iface, 'items_tree'):
-                for item in iface.items_tree:
-                    if item.item_type == 'SOCKET' and item.in_out == 'INPUT':
-                        name_to_sid[item.name] = (item.identifier, item.socket_type)
+            if not iface or not hasattr(iface, 'items_tree'):
+                continue
 
-            for item in (getattr(iface, 'items_tree', []) if iface else []):
+            # Snapshot fragile sockets BEFORE any writes
+            snapshot = _snapshot_fragile_sockets(obj, mod, iface)
+
+            name_to_sid = {}
+            for item in iface.items_tree:
+                if item.item_type == 'SOCKET' and item.in_out == 'INPUT':
+                    name_to_sid[item.name] = (item.identifier, item.socket_type)
+
+            for item in iface.items_tree:
                 if item.item_type != 'SOCKET' or item.in_out != 'INPUT':
                     continue
                 sid = item.identifier
@@ -77,6 +113,14 @@ def fix_lib_overrides():
                 if "Reset Children" in name_to_sid:
                     mod[name_to_sid["Reset Children"][0]] = True
                     fixed += 1
+
+            # Restore any fragile sockets that got wiped
+            restored = _restore_fragile_sockets(mod, snapshot)
+            if restored:
+                print(f"  [RESTORE] {obj.name}/{mod.name}: "
+                      f"restored {restored} Material/Object sockets")
+            fixed += restored
+
     return fixed