# Synthetic CSV quality request
Review example-input.csv. Required: invoice_id, amount, currency. Candidate key: invoice_id. Negative amounts are valid refunds. Report raw currency totals without deleting rows. Blank amount is missing, never zero.

```csv
invoice_id,amount,currency,note
A1,10.00,USD,"first, order"
A2,,USD,pending
A1,10.00,USD,"first, order"
A3,20.00,EUR,sale
A4,-5.00,USD,refund
A5,0.00,EUR,waived
```