Matrixx0070 XLSX — deliverable doctrine
Full doc: skills/xlsx/references/FULL_SKILL.md. Tools:
spreadsheet.create/read/pivot/chart/validate (exceljs) and
spreadsheet.recalc (LibreOffice — the only thing that actually
evaluates formulas).
The two iron rules
- Use formulas, not hardcoded values. Never compute in Python/JS and
write the result into a cell. Write
=SUM(B2:B9),=(C5-B5)/B5,=AVERAGE(...)so the workbook stays live when the user edits inputs. Hardcoding calculated values is the #1 rejected-deliverable cause. - Zero formula errors. Every delivered workbook must be run through
spreadsheet.recalcand come back clean — no #REF!, #DIV/0!, #VALUE!, #NAME?, #NULL!, #NUM!, #N/A anywhere.errors_found= not done: fix and re-run. Guard divisions (=IF(B1=0,0,A1/B1)) and check ranges after inserting/deleting rows.
Library routing
- openpyxl — creating/editing .xlsx with formulas + formatting; loading preserves existing formulas/styles. Edit existing files with openpyxl, not pandas.
- pandas — bulk data analysis in/out (
read_excel,to_excel); loses formulas and formatting, so never round-trip a styled workbook through it. - Reading values only:
load_workbook(path, data_only=True)returns cached results (runspreadsheet.recalcfirst if you just wrote formulas).
Financial models (unless the user/template says otherwise)
- Color code text: BLUE = hardcoded inputs users will change; BLACK = formulas/calculations; GREEN = links pulling from other worksheets.
- Number formats: right-align numbers; thousands separators; negatives in parentheses; currency symbol on first row + totals only; percentages with 1–2 decimals; consistent decimal places per row/column.
- One consistent professional font (e.g. Arial); years as column headers; assumptions clearly separated from outputs.
Templates override everything
When updating an existing file: study its fonts, colors, number formats, and formula style FIRST and match them exactly. Never impose the standards above on a workbook with established conventions.
Verify before delivering
spreadsheet.recalc→ status must besuccess(zero errors).- Re-read computed values (
data_only=True) and sanity-check magnitudes — a formula that evaluates to 0 or 8 digits where you expected 5 is wrong. - Spot-check one formula per block by hand.