Should you build your own Finary?

Build a local personal net worth tracker. Single user, runs on my machine, no accounts, no cloud, no telemetry.

Stack, non negotiable: Next.js 15 with the App Router and TypeScript, Tailwind for styling, SQLite through better-sqlite3 with plain SQL migrations in /db, Recharts for charts. No ORM, no auth library, no external UI kit.

Data model:
- accounts: id, name, institution, type (cash, brokerage, retirement, crypto, property, loan), currency
- holdings: id, account_id, symbol (nullable), quantity, manual_value (nullable), cost_basis (nullable)
- prices: symbol, date, close, currency
- snapshots: date, total_value, breakdown_json

Features:
1. CRUD pages for accounts and holdings. Holdings are either priced by symbol or carry a manual value for things like property and cash.
2. CSV import at /import: paste or upload a CSV, map columns to symbol, quantity, cost basis, pick the target account, preview before commit.
3. A price refresh route that pulls crypto quotes from CoinGecko and equity or ETF quotes from a single configurable HTTP quote endpoint. Cache into the prices table, never hit the network on page render.
4. A snapshot script, npm run snapshot, that recomputes total net worth and writes one row to snapshots. Document how to run it daily with cron or Task Scheduler.
5. Dashboard: total net worth, net worth line chart from snapshots, allocation donut by asset type, table of holdings with value, weight, and gain versus cost basis.
6. Multi currency: store a base currency in .env, fetch FX rates in the same refresh job, convert everything to base for display.

Out of scope, do not attempt: bank or broker account linking, open banking or PSD2 aggregators, credential scraping, mobile apps, multi user support, tax reporting.

Secrets in .env.example: BASE_CURRENCY, COINGECKO_API_KEY, QUOTE_API_URL, QUOTE_API_KEY, FX_API_URL. Never commit real keys.

Seed the database with three fake accounts and eight holdings so the dashboard is not empty on first run. Write a README with setup, refresh, and snapshot instructions in under thirty lines.