- empty graph produces header-only CSVs (no data rows)
- empty graph relCSV has only header
- double quotes in node names are RFC 4180 escaped
- file node without fileContents gets empty content (no crash)
- community with empty keywords array produces valid CSV
- unknown node labels are silently skipped
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>