Turn our messy family spreadsheet into a phone dashboard we both trust
Marco Madonna spent three days in October having the AI turn the Excel workbook he and his partner use to run their house into a phone dashboard backed by the same Google Sheet, which was never replaced. The AI first mapped the workbook and flagged a total that didn't add up, the app now writes expenses and budgets back into the sheet, monthly broker reports are imported only if every check passes, and a verification script matched 50 checks against the sources with zero unexplained differences — plus it spotted a kids' savings payment likely credited to the wrong contract.
How it works
- Brief the AI: no app code until the data is understood
- It produces a data dictionary of the workbook and asks about a savings total that doesn't match instead of fixing it silently
- Workbook copied to a native Google Sheet with added flat tabs, his own tabs untouched
- Build four pages (overview, shared plan and settle-up, savings, broker portfolio)
- Second round: dashboard writes expenses, paid ticks and budgets back into source cells, refusing to overwrite formulas
- Broker reports imported manually with layout, contract and totals checks; if anything fails, nothing is imported
- Verification script compares app against sheet and reports: 50 checks matched, 2 explained differences, 0 unexplained
Why it’s worth knowing
The builder app reconciled itself against his own spreadsheet to the cent — and caught a savings payment sitting on the wrong child's contract.
Where it’s from
Summarized from a public post on medium.com. See the original ↗