# DAL Persistence and Cache Policy

## Responsibilities

- Repositories coordinate provider calls for aggregate persistence.
- Cache invalidation policy is owned by DAL.
- Service layer does not implement persistence or cache invalidation details.
- Cache invalidation boundaries are expressed through DAL contract interfaces.

## Policy

- Persistence writes must define cache invalidation triggers.
- Cache keys and invalidation behavior are centralized in DAL policy definitions.
- This stage defines contracts, ports, and adapters only; no persistence implementation is introduced.