{
  "source_rows": 4,
  "output_rows": 4,
  "exact_duplicate_rows_flagged": 1,
  "issues": [
    {
      "source_line": 5,
      "reason": "empty_mapped_field"
    }
  ],
  "mapping": {
    "Client ID": "customer_id",
    "Customer": "customer_name",
    "Order Total": "order_total"
  },
  "data_loss_policy": "no rows deleted; source values preserved"
}