in design_system.py, the persist_design_system function crashes if it's called with the default project_name=None. It tries to run project_name.lower(), which raises: AttributeError: 'NoneType' object has no attribute 'lower'.

Evidence:
core.py:L112

• The length filter responsible for the search blindness.
  design_system.py:L508
• The missing null check for project naming.