Get a transaction's receipt

What your assistant is told

Read the receipt stored on one transaction: its header (shop, issue date, card digits), its items with each one's category, and the derived split — the per-category subtotals plus the "Not itemised" remainder that keeps the split equal to the payment. Call it before editing anything, because update_receipt_item and delete_receipt_item need the item ids this returns. An error says the transaction has no receipt; that is not a problem, it just means the whole payment counts in the transaction's own category. Read-only.