Ledger
Internal money-movement tool where every change was visible, auditable, and — when needed — reversible.
Problem
Internal money movement lived across systems that didn’t agree. Reconciliation was manual, slow, and quietly error-prone.
Role
Built the append-only ledger model, workflows, and operator UI alongside finance stakeholders.
Approach
Every change as an immutable event with a reason; balances derived from the log. Truth became reconstructable by design.
Architecture
Temporal for multi-step ops with retries and compensation; Postgres as the system of record; React for review and audit trails.
Outcome
Migrated one transaction type at a time with shadow reconciliation until the new ledger matched the legacy process to the cent.
Lessons
Reversibility is a feature. Explaining and unwinding a decision mattered more than raw speed.