        mapping=output.get('mapping')
        source_names={row['source'] for row in case['input']['styles']}
        if set(output)!={'mapping'} or not isinstance(mapping,dict) or set(mapping)!=source_names or any(not isinstance(value,str) or value not in {'BodyImported','HeadingImported'} for value in mapping.values()):
            return reject_shape('Expected only top-level mapping containing every source style key and allowed target style names; unwrapped keys are not silently normalized')
