# Ledger

> Financial ledger - transactions, audit trails. Use when tracking money.

- Skill: `majiayu000/ledger-2` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/ledger-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/ledger-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/ledger-2

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# Ledger Guideline

## Tech Stack

* **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
* Every balance must be provable by replaying the ledger

## Context

Ledger handles financial integrity — transaction history, balance correctness, audit trail. Payment processing lives in `billing`, pricing strategy lives in `pricing`.

A bug that creates or destroys money is a serious incident. This must be bulletproof.

## 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?