Ledger Guideline

Tech Stack

• Payments: Stripe
• Database: Neon (Postgres)
• ORM: Drizzle

Non-Negotiables

• Balances must be immutable ledger (append-only), not mutable fields
• No floating-point for money (use deterministic precision)
• All financial mutations must be idempotent
• Monetary flows must be reconcilable with Stripe

Context

Financial systems are unforgiving. A bug that creates or destroys money — even briefly — is a serious incident. Users trust us with their money; that trust is easily lost and hard to regain.

If balance/credits/wallet exists, it must be bulletproof. If it doesn't exist yet, consider whether the current design would support adding it correctly. Retrofitting financial integrity is painful.

Driving Questions

• Does a balance/credits system exist, and is it implemented correctly?
• Where could money be created or destroyed by a bug?
• What happens during concurrent transactions?
• How would we detect if balances drifted from reality?
• Can we prove every balance by replaying the ledger?
• What financial edge cases (refunds, disputes, chargebacks) aren't handled?