Petasos Finance Vault.

A Hermes Agent skill — a package that lets the open-source Hermes AI assistant do a job for you — that keeps track of a family’s money. Petasos reads the alert emails your bank sends, records every transaction in a simple ledger you own inside Obsidian, and re-checks the math after every change — so any question about your balance or spending is answered from verified numbers, never from memory.

Where it earns its keep

• Cash spent on the go — mention it in chat or run one command, and it’s recorded on the spot, never left for a cleanup later.
• Every morning — it fetches new bank alerts, checks that each amount matches the running balance, files the transaction, and asks about anything it isn’t sure of — once.
• “Wait, did this month balance?” — answered from verified records. If the math doesn’t hold, it says so before any report is produced.
• End of the month — one command locks the month’s totals and saves a full snapshot; closed months can’t quietly change later.

How it’s built

• One ledger, never edited by hand. Every entry goes in through a checked command; the ledger file only ever grows — nothing is overwritten or deleted.
• The math must pass. After every change it re-checks that entries are unique, balances add up, and the running chain holds. A preview mode shows exactly what would change before anything is written.
• Your rules, your data. How each bank’s emails look and how purchases are categorized live in two plain files in your vault — adding a new bank is one entry, no code changes.
• Months close like accounting books. Totals are frozen with a snapshot as a restore point, and two processes can never write at the same time.

It needs only Python and one small library.