Xlsx

This handles the full spreadsheet workflow: reading data with pandas, creating and editing files with openpyxl, and most importantly, recalculating formulas through LibreOffice so you're not just writing formula strings into cells. It enforces zero formula errors as a hard requirement and ships with detailed guidelines for financial modeling (blue for inputs, black for formulas, proper number formatting). The recalc.py script scans every cell for errors and returns JSON with locations, which matters because openpyxl alone won't catch broken references or division by zero. The documentation is opinionated about using Excel formulas instead of hardcoding Python calculations, which keeps spreadsheets dynamic. Use this when you need Claude to build actual working models, not just dump data into cells.