What problem does it solve? Spreadsheet tasks often produce broken formulas, hardcoded values, and inconsistent formatting when done ad hoc. This Skill provides a disciplined workflow for creating, editing, and analyzing .xlsx, .xlsm, .csv, and .tsv files so every deliverable uses live Excel formulas, follows financial-modeling conventions, and ships with zero formula errors. ## Core Features & Use Cases - Formula-first spreadsheet generation: Builds workbooks with openpyxl using real Excel formulas (SUM, AVERAGE, growth rates) instead of Python-hardcoded values, keeping files dynamic and recalculable. - Mandatory recalculation and error scanning: The scripts/recalc.py tool drives LibreOffice headlessly to recalculate all formulas and reports any #REF!, #DIV/0!, #VALUE!, #NAME?, or #N/A errors with exact cell locations. - Financial modeling standards: Enforces industry color conventions (blue inputs, black formulas, green cross-sheet links), number formatting rules, and source documentation for hardcoded values. - Use Case: A user asks to build a revenue projection model from a messy CSV export. The Skill cleans the data with pandas, constructs a formatted workbook with assumption cells and formulas, recalculates it via LibreOffice, and fixes any reported errors before delivery. ## Quick Start Ask the assistant to create an Excel financial model from your data file with formulas for totals and growth rates, then recalculate and verify it contains no formula errors.