feat(F-189): completed feature

project/src/modules/pos/domain/pos-sale.ts

@@ -105,6 +105,10 @@ export interface PosReceipt {
   header: string | null;
   returnPolicy: string;
   footer: string | null;
+  /** Present on return receipts. References the original ticket number. */
+  originalReceiptNumber?: string;
+  /** True for return/reversal receipts that should print negative totals. */
+  isReturn?: boolean;
 }
 
 export interface PosSaleResult {
@@ -125,3 +129,27 @@ export interface PosSaleResult {
 export interface PosPaymentResult extends PosReceiptPayment {
   id: string;
 }
+
+export interface PosReturnLineInput {
+  orderItemId: string;
+  returnedQuantity: number;
+}
+
+export interface PosReturnInput {
+  orderId: string;
+  idempotencyKey: string;
+  cashSessionId: string;
+  terminalId: string;
+  userId: string;
+  reason: string;
+  lines: PosReturnLineInput[];
+}
+
+export interface PosReturnResult {
+  orderId: string;
+  returnId: string;
+  idempotencyKey: string;
+  state: 'PARTIALLY_REFUNDED' | 'REFUNDED';
+  refundedCents: number;
+  receipt: PosReceipt;
+}