What problem does it solve? Working with Excel files programmatically often corrupts advanced features like pivot tables, VBA macros, and sparklines when libraries round-trip the file, and generated spreadsheets frequently contain hardcoded values instead of live formulas. This Skill solves both problems by operating directly on the OOXML (SpreadsheetML) inside the xlsx package, preserving everything untouched while enforcing formula-first, professionally formatted output. ## Core Features & Use Cases - Five task paths: READ (analyze data with pandas), CREATE (build new workbooks from an XML template), EDIT (surgical unpack-edit-repack changes with zero format loss), FIX (repair broken formulas like #REF! and #DIV/0!), and VALIDATE (static formula checking). - Financial formatting standards: Applies the industry color convention (blue = input, black = formula, green = cross-sheet reference) plus currency, percentage, and year number formats through a 13-slot pre-built style system. - Helper scripts: Includes xlsx_unpack/xlsx_pack, formula_check, xlsx_add_column, xlsx_insert_row, and xlsx_shift_rows for deterministic structural edits. - Use Case: A user asks to add a "% of Total" column to an existing budget workbook. The Skill unpacks the file, inserts the column with live formulas and copied styles, repacks it, and validates the result—without touching the file's pivot tables or macros. ## Quick Start Ask the assistant to create a three-year revenue model in Excel with live formulas and financial formatting, or to edit a specific cell in an existing xlsx file.