fix: error on duplicate node labels in mkconcore and validate

Author: avinxshKD

concore_cli/commands/validate.py

@@ -117,7 +117,14 @@ def finalize():
                     warnings.append(f"Node {node_id} has no label")
             except Exception as e:
                 warnings.append(f"Error parsing node: {str(e)}")
-        
+
+        # duplicate labels cause silent corruption in mkconcore.py (#384)
+        seen = set()
+        for label in node_labels:
+            if label in seen:
+                errors.append(f"Duplicate node label: '{label}'")
+            seen.add(label)
+
         node_ids = {node.get('id') for node in nodes if node.get('id')}
         for edge in edges:
             source = edge.get('source')

mkconcore.py

@@ -307,6 +307,12 @@ def cleanup_script_files():
     except (IndexError, AttributeError):
         logging.debug('A node with no valid properties encountered and ignored')
 
+label_values = list(nodes_dict.values())
+duplicates = {label for label in label_values if label_values.count(label) > 1}
+if duplicates:
+    logging.error(f"Duplicate node labels found: {sorted(duplicates)}")
+    quit()
+
 for edge in edges_text:
     try:
         data = edge.find('data', recursive=False)