💰 Finance & Fintech · Payments Engineering

Design a double-entry ledger that balances forever

Immutable journal entries, balanced postings, and derived balances keeping money math provable.

advanced~45 minFintech EngineersFinancial AnalystsRisk Teams

Steps

1Model money as immutable journal entries; never UPDATE amounts
2Enforce sum(debits) = sum(credits) per transaction at DB level
3Store original currency + rate snapshot per entry, not converted-only
4Derive balances from entries; materialize views for speed, recompute nightly
5Reconcile internal ledger to processor reports daily with diff alerts
6Freeze periods: no edits into closed accounting periods, adjustments are new entries

Common Pitfalls

▲Mutable balance columns drifting from entry truth
▲FX conversion applied twice across services

Commands

Install with skills CLI

$ npx skills add aniruddhaadak80/skills --skill payments-engineering-ledger-design-double-entry

Install globally

$ npx skills add aniruddhaadak80/skills --skill payments-engineering-ledger-design-double-entry -g

Tags

#ledger#payments#accounting#finance-fintech#payments-engineering

Install this skill

$ npx skills add aniruddhaadak80/skills --skill payments-engineering-ledger-design-double-entry -a opencode

SKILL.md

# Design a double-entry ledger that balances forever

> Immutable journal entries, balanced postings, and derived balances keeping money math provable.

## When to Use This Skill

Immutable journal entries, balanced postings, and derived balances keeping money math provable.

## Steps

1. Model money as immutable journal entries; never UPDATE amounts
2. Enforce sum(debits) = sum(credits) per transaction at DB level
3. Store original currency + rate snapshot per entry, not converted-only
4. Derive balances from entries; materialize views for speed, recompute nightly
5. Reconcile internal ledger to processor reports daily with diff alerts
6. Freeze periods: no edits into closed accounting periods, adjustments are new entries

## Common Pitfalls

- Mutable balance columns drifting from entry truth
- FX conversion applied twice across services

View source on GitHub ↗

Idempotent handlers, signature checks, and replay safety for provider callbacks.

💰 Finance & Fintech·~35m

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