Domain
Finance
Every transaction from my own banks, kept as evidence and classified by what kind of movement it was.
The hardest part of personal finance software was never the charts. It was categories that did not hold up, and data that was already out of date by the time I looked at it. Finance starts from the transactions themselves and a small model of what money can do.
A model can reason over amounts, merchants and categories when I ask. Account numbers and payment references are always masked.
Where the data comes from
- A read-only bank feed
- Transactions arrive as they happen from a read-only bank feed. Finance can see them; it can never move money.
- No record copy
- Bank data is already structured, so it stands as evidence on its own. Transcribing it into a second record would only add room for mistakes.
How a transaction is understood
- 01
Flows
Every transaction is first one kind of movement: income, spending, refund, transfer, capital or debt. Most questions about money start here.
- 02
A short category list
Categories are chosen for reasoning, charting and calculation, not personal taste. A new one is added only when real transactions need it.
- 03
Dimensions
Facts such as who a payment was for are dimensions, not categories. People's circumstances change; the category should not have to.
- 04
My corrections come first
Rules categorise most transactions. When I correct one by hand, my correction always wins.
The Finance app
- Periods
- Named stretches of time, such as a holiday, so I can ask about a period instead of a date range.
- Saved investigations
- A good answer from chat can be kept in Finance and run again later on new data.
- Recurring payments
- Subscriptions and repeating charges, found from the transactions themselves.
- Obligations linked to documents
- An insurance payment can be linked to its policy in Household, so the money and the document point at each other.
The app lives in the console, and its chat can answer questions such as what I spent on a trip or which subscriptions I still pay. The rule that structured documents stand without a record is part of the constitution.
Finance is where I learned that not every source needs the same evidence rules. Bank data arrives structured already, so it stands as evidence without a record.