# Edge Cases & Controls

## Common Edge Cases

- **Duplicate File Detection:** Identify and reject duplicate submissions.
- **Date Mismatch Handling:** Correct or reject transactions with invalid dates.
- **Core Rejection Handling:** Manage rejections from core systems.

## Controls

- **Idempotency:** Ensure transactions are processed only once.
- **Audit Logging:** Maintain logs for all transactions.
- **Reconciliation Safeguards:** Verify transaction totals and balances.