refactor: record a list of all transaction IDs completed for the call

lib/lambda/c3-submit-payment/index.js

@@ -58,9 +58,19 @@ export async function handler(event) {
 			: response.transaction.bankAccountNumber;
 	const endingDigits = maskedNumber.slice(-4);
 
+	// Update the list of all transaction IDs.
+	const previousTransactionIds = contactAttributes.TransactionIds
+		? JSON.parse(contactAttributes.TransactionIds)
+		: [];
+	const newTransactionIds = [
+		...previousTransactionIds,
+		response.transaction.id,
+	];
+
 	return {
 		TransactionApproved: response.transactionApproved,
 		TransactionId: response.transaction.id,
+		TransactionIds: JSON.stringify(newTransactionIds),
 		TransactionMeta: response.transactionMeta,
 		PaymentMethodEndingDigits: endingDigits,
 	};