spreadsheets

Spreadsheets

Produce XLSX deliverables with openpyxl, and edit workbooks that already exist with LibreOffice Calc. Follow every section below before declaring a workbook done.

Never round-trip an existing workbook with openpyxl

openpyxl writes new workbooks. It never touches a file that already exists — not to change one number, not for a "quick value edit".

load_workbook(path) followed by .save(path) does not edit the file; it rebuilds it from the parts openpyxl models, and everything else is gone. In practice that means silently losing:

• formula results the engine computed — openpyxl drops the cached values, so every formula reads as empty until someone opens the file in Excel
• named ranges, pivot tables and their caches
• charts, images, and shapes
• conditional formatting and data validation
• macros, custom styles, and sheet protection

None of this raises an error. The file saves, looks plausible in an inspection script, and hands the user a gutted copy of their own workbook.

Read-only inspection is fine and expected: load_workbook(path, read_only=True) or data_only=True, with no .save() anywhere near it. The bundled analyze_xlsx.py does exactly this.

Installing the library

Install the pinned dependency with its own exec call — commands have a bounded wall clock, and one pip invocation per package stays inside it:

python3 -m pip install --user openpyxl==3.1.5

Installs work only when this chat's network policy allows package managers, and they persist for the rest of the conversation. If an install is refused by policy, do not retry: tell the user to enable the package-manager network policy for this chat, and offer the closest format you can produce without the library (CSV) — only with their knowledge, never as a silent substitution. If a dependency cannot be installed at all, say so plainly instead of quietly delivering a lesser format.

Creating a new workbook

A workbook built from scratch is openpyxl's job, with the formula and layout rules below. Nothing in this section changes because of the edit path.