Ledger

A small personal finance ledger for importing Revolut CSV exports into SQLite, running spending reports, and exposing ledger/currency utilities over MCP.

What It Does

• Imports Revolut CSV rows into a normalized ledger_entries table.

• Stores ledger data in a local SQLite database.

• Generates JSON reports for merchant spending and largest expenses.

• Provides an MCP stdio server with ledger report tools and currency conversion.

• Uses TypeScript, Vitest, oxlint, and oxfmt for development checks.

Requirements

• Node.js >=22.18

• npm

Setup

npm install

Initialize the default local database at data/ledger.sqlite:

npm run db:init

You can pass a custom database path directly to the underlying CLI:

node src/cli/init-db.ts path/to/ledger.sqlite

Import Revolut Data

Inspect a Revolut CSV export before importing:

npm run inspect:revolut -- path/to/revolut.csv

Import rows into the default database:

npm run import:revolut -- path/to/revolut.csv

Import into a custom database:

npm run import:revolut -- path/to/revolut.csv path/to/ledger.sqlite

Imports are idempotent per source file and source row. Duplicate rows are skipped using the database uniqueness constraint.

Reports

Find monthly spending for a merchant:

npm run report:monthly-merchant -- "Merchant Name"

Find the month with the most posted card payments for a merchant:

npm run report:busiest-merchant-month -- "Merchant Name"

Find the largest expense, optionally filtered:

npm run report:largest-expense -- --merchant "Merchant Name"
npm run report:largest-expense -- --date-from 2026-01-01 --date-to 2026-01-31
npm run report:largest-expense -- --time-from 12:00 --time-to 14:00

All report commands print JSON.

MCP Server

Start the stdio MCP server:

npm run mcp:server

By default, the server reads from data/ledger.sqlite. Set LEDGER_DB_PATH to point at another database:

LEDGER_DB_PATH=path/to/ledger.sqlite npm run mcp:server

Available MCP tools:

• find_busiest_merchant_month

• find_largest_expense

• find_total_merchant_spending

• convert_currency

Smoke-test the MCP clients:

npm run mcp:smoke

Development

Run the full check suite:

npm run check

Run individual checks:

npm run typecheck
npm test
npm run lint
npm run format:check

Format and lint-fix locally:

npm run format
npm run lint:fix

Project Layout

src/agent/          Local agent/MCP chat helpers
src/cli/            Command-line entry points
src/domain/         Core ledger, money, date, time, and currency types
src/exchange-rates/ NBP exchange-rate integration
src/importers/      Source-specific importers, currently Revolut
src/mcp/            MCP server and smoke clients
src/presentation/   Formatting helpers
src/reports/        Report queries and calculations
src/storage/        SQLite setup and persistence helpers
src/tools/          MCP tool implementations

Notes

• Currency support is currently limited to PLN, CHF, and EUR.

• Currency conversion uses the latest NBP table A average exchange rates.

• The SQLite database is local; keep personal export files and database files out of version control.