// lib/accounting/core/README.immutable-policy.md

# Immutable Policy (WP-01)

## Purpose

- Enforces immutability of all posted documents and journal entries
- Prevents any modification or deletion after posting
- Used in posting, migration, and audit scenarios

## Usage

- Use `assertImmutable(document)` to enforce immutability before any posting or update

## Example

```ts
assertImmutable(document);
```

---

> **Note:** Immutability is mandatory for all posting and migration scenarios.
