fix(utils): only assign socket values if they differ to prevent library override reload wipes

When fix_lib_overrides() writes to any mod[sid] on a GeoNode modifier,
Blender can re-evaluate ALL library overrides on that modifier, wiping
Material and Object sockets back to their library defaults (NONE).

Fix: snapshot all fragile sockets (NodeSocketMaterial, NodeSocketObject)
before any modifications, then restore them if they got wiped.

utils.py

@@ -16,6 +16,38 @@ def silence_puresky():
     return removed
 
 
+def _snapshot_fragile_sockets(obj, mod, iface):
+    """Snapshot Material/Object sockets before modifying any override."""
+    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]
+            # Debug output to verify we grab the material
+            # print(f"  [SNAPSHOT] {obj.name} -> {item.name}: {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
+        # Force restore if the current value no longer matches our snapshot
+        if current != value:
+            try:
+                mod[sid] = value
+                restored += 1
+            except Exception as e:
+                print(f"  [RESTORE FAILED] {sid}: {e}")
+    return restored
+
+
 def fix_lib_overrides():
     fixed = 0
     for obj in bpy.data.objects:
@@ -28,14 +60,19 @@ def fix_lib_overrides():
                 continue
 
             ng = mod.node_group
-            name_to_sid = {}
             iface = getattr(ng, 'interface', None)
-            if iface and hasattr(iface, 'items_tree'):
+            if not iface or not hasattr(iface, 'items_tree'):
+                continue
+
+            # 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 (getattr(iface, 'items_tree', []) if iface else []):
+            for item in iface.items_tree:
                 if item.item_type != 'SOCKET' or item.in_out != 'INPUT':
                     continue
                 sid = item.identifier
@@ -54,29 +91,51 @@ def fix_lib_overrides():
             ng_name = ng.name
             if ng_name == "Add Shader v1.0":
                 if "Filter by ID" in name_to_sid:
-                    mod[name_to_sid["Filter by ID"][0]] = True
+                    sid = name_to_sid["Filter by ID"][0]
+                    if mod.get(sid) != True:
+                        mod[sid] = True
                         fixed += 1
                 if "ID" in name_to_sid and name_to_sid["ID"][1] == "NodeSocketString":
-                    mod[name_to_sid["ID"][0]] = "Index"
+                    sid = name_to_sid["ID"][0]
+                    if mod.get(sid) != "Index":
+                        mod[sid] = "Index"
                         fixed += 1
             elif ng_name in ["Add Shaders by Index v1.0", "Make Material", "Make Labels"]:
                 if "ID" in name_to_sid and name_to_sid["ID"][1] == "NodeSocketString":
-                    mod[name_to_sid["ID"][0]] = "Index"
+                    sid = name_to_sid["ID"][0]
+                    if mod.get(sid) != "Index":
+                        mod[sid] = "Index"
                         fixed += 1
                 if ng_name == "Make Labels" and "Shrinkwrap" in name_to_sid:
-                    mod[name_to_sid["Shrinkwrap"][0]] = True
+                    sid = name_to_sid["Shrinkwrap"][0]
+                    if mod.get(sid) != True:
+                        mod[sid] = True
                         fixed += 1
             elif ng_name == "Make attached":
                 if "Reset Children" in name_to_sid:
-                    mod[name_to_sid["Reset Children"][0]] = True
+                    sid = name_to_sid["Reset Children"][0]
+                    if mod.get(sid) != True:
+                        mod[sid] = True
                         fixed += 1
                 if "Separate Children" in name_to_sid:
-                    mod[name_to_sid["Separate Children"][0]] = True
+                    sid = name_to_sid["Separate Children"][0]
+                    if mod.get(sid) != True:
+                        mod[sid] = True
                         fixed += 1
             elif ng_name == "Proxy v1.0":
                 if "Reset Children" in name_to_sid:
-                    mod[name_to_sid["Reset Children"][0]] = True
+                    sid = name_to_sid["Reset Children"][0]
+                    if mod.get(sid) != True:
+                        mod[sid] = 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