Designing a ledger wallet: auditability first
Why a balance column isn't enough—and how double-entry thinking pays off in debugging and compliance.
A wallet with a single balance field is simple until something goes wrong. Where did the money go? When? Why is the balance off by $0.01?
A ledger records every debit and credit as an immutable entry. Balance is derived, not stored. You can replay history, audit any transaction, and reconcile against external systems.
The tradeoff is schema complexity and write volume. For any system where money moves and regulators ask questions, auditability first is the right default.