Tags can have slashes, too, as a treat

lc/model.py

@@ -224,7 +224,7 @@ class Tag(Model):
 
     @staticmethod
     def is_valid_tag_name(tag_name: str) -> bool:
-        return all((c.isalnum() for c in tag_name))
+        return all((c.isalnum() or c == '/' for c in tag_name))
 
     @staticmethod
     def get_or_create_tag(user: User, tag_name: str) -> 'Tag':