Why I enforce my ledger's invariant twice
The naive approach When I started thinking about how to track balances, the first thing I reached for was a single UPDATE: UPDATE accounts SET balance = balance + 100 WHERE id = 42; It works. Unt
Series
Building a Double-Entry Ledge
A 6-week, build-in-public series. I'm building a production-style double-entry ledger API in Go and Postgres, with a React dashboard and a small marketplace demo on top. One post every Sunday
Posts in this series
What was my cash balance on March 15? In dollars?
The naive answer to "what was my cash balance on March 15?" is one line of SQL: SELECT SUM(...) FROM entries WHERE account_id = $1 AND created_at <= '2026-03-15'; That works for one currency. In doll
Streaming a ledger without melting React
Week 3 of 6 · Building a Double-Entry Ledger The naive approach When I built the live clock for my dashboard's header, the first thing I reached for was a single useState: const [now, setNow] = useSt
Adding multi-tenancy to a Postgres ledger without a rewrite
Application-scoping, cross-tenant isolation tests, and the trade-off I made over Postgres RLS.
Teaching a Postgres ledger to rewind
A play button and a load-test button, and the invariant that survives both.
