What problem does it solve? Working with spreadsheet files programmatically is error-prone: openpyxl writes formulas without cached values, modern Excel functions break under LibreOffice, and external workbook links get silently destroyed. This Skill provides the operational rules and scripts to produce correct, formula-driven .xlsx, .xlsm, .xltx, .csv, and .tsv files without shipping broken workbooks. ## Core Features & Use Cases - Spreadsheet creation and editing: Build new workbooks or edit existing ones with openpyxl and pandas, following strict conventions for fonts, number formats, and financial-model color coding. - Mandatory formula recalculation: The scripts/recalc.py tool runs LibreOffice headless to compute every formula, rewrites the file in place, and reports JSON error summaries naming exact cells with #VALUE!, #REF!, #NAME?, and other errors. - External-link protection: Detects formulas referencing other workbooks whose cached values would be lost on save, and refuses to recalculate unless --force is passed. - Use Case: A user asks to add a revenue projection tab to an existing financial model. The Skill writes SUMIFS and INDEX/MATCH formulas, recalculates with recalc.py, fixes any reported error cells, and delivers a workbook that recomputes when inputs change. ## Quick Start Use the xlsx skill to create a new spreadsheet from my sales data with a summary tab of formulas, then recalculate it and fix any formula errors.
