What problem does it solve? Working with spreadsheet files programmatically often leads to broken formulas, inconsistent formatting, and hardcoded values that make files impossible to maintain. This Skill provides a structured workflow for creating, editing, and analyzing .xlsx, .xlsm, .csv, and .tsv files so deliverables arrive with zero formula errors and professional formatting. ## Core Features & Use Cases - Formula-first spreadsheet generation: Writes native Excel formulas (SUM, AVERAGE, growth rates) instead of hardcoded Python-computed values, keeping workbooks dynamic and recalculable. - Automated recalculation and error detection: The scripts/recalc.py tool uses LibreOffice to recalculate all formulas and reports #REF!, #DIV/0!, #VALUE!, #NAME?, and other errors with exact cell locations. - Financial modeling conventions: Enforces industry-standard color coding (blue inputs, black formulas, green cross-sheet links), number formats ($#,##0, 0.0%, 0.0x), and assumption documentation. - Use Case: A user asks to build a revenue forecast model from a messy CSV export. The Skill cleans the data with pandas, builds the model with openpyxl using cell-referenced assumptions, recalculates via LibreOffice, and fixes any formula errors before delivery. ## Quick Start Ask the assistant to create or edit an Excel file, for example: build a financial model spreadsheet from my sales data with formulas and proper formatting.