fix fallback base on show product

src/utils/productCategories.ts

@@ -32,6 +32,20 @@ export function isMeltedTradeGroup(groupType?: string | null) {
   return group === PRODUCT_CATEGORY_ABSHODE || LEGACY_MELTED_GROUP_TYPES.includes(group as typeof LEGACY_MELTED_GROUP_TYPES[number])
 }
 
+export interface QuantityTradeProductSource {
+  group_type?: string | null
+  trade_by_quantity?: boolean | number | null
+}
+
+/** معامله مقداری: فقط فیلد trade_by_quantity — بدون وابستگی به دسته‌بندی */
+export function usesQuantityTrade(product?: QuantityTradeProductSource | null) {
+  if (!product) {
+    return false
+  }
+
+  return product.trade_by_quantity === true || Number(product.trade_by_quantity) === 1
+}
+
 export function isMetalCommodityGroup(groupType?: string | null) {
   const group = normalizeProductGroupType(groupType)
   return group === 'مس' || group === 'نقره'

src/utils/productDealMethod.ts

@@ -56,10 +56,24 @@ export function isWeightBasedProductUnit(unit?: string | null) {
 
 const COUNT_BASED_GROUP_TYPES = ['سکه', 'گوی', 'مکعب', 'شمش', 'سکه پارسیان']
 
-/** مطابق ادمین: وزن «دارد» یعنی amount مقدار واقعی است؛ «ندارد» یعنی amount = 1 */
+/** مطابق ادمین: وزن «دارد» => amount > 0 ؛ «ندارد» => amount = 0 */
 export function hasProductUnitWeight(product?: ProductUnitSource | null) {
+  if (isMeltedTradeGroup(product?.group_type)) {
+    return false
+  }
+
   const amount = Number(product?.amount ?? 0)
-  return amount > 0 && amount !== 1
+  return amount > 0
+}
+
+/** ضریب قیمت — محصول بدون وزن قطعه همیشه ۱ */
+export function productPriceAmountFactor(product?: ProductUnitSource | null) {
+  if (hasProductUnitWeight(product)) {
+    const amount = Number(product?.amount ?? 0)
+    return amount > 0 ? amount : 1
+  }
+
+  return 1
 }
 
 export function getProductWeightUnit(product?: ProductUnitSource | null) {

src/utils/productPrice.ts

@@ -1,6 +1,7 @@
 import type { Product } from '@/models/products'
 import { getTradeBuyPrice, getTradeSellPrice, lastPrice } from '@/utils/price'
-import { isMetalCommodityGroup, isMeltedProductUsingAppPrice, isMeltedTradeGroup } from '@/utils/productCategories'
+import { isMetalCommodityGroup, isMeltedProductUsingAppPrice, isMeltedTradeGroup, usesQuantityTrade } from '@/utils/productCategories'
+import { productPriceAmountFactor } from '@/utils/productDealMethod'
 
 function productUsesLastPriceIfZero(product: Product): boolean {
   return Boolean(product.use_last_price_if_zero)
@@ -89,13 +90,14 @@ export function getProductBuyPrice(product: Product): number {
     isMeltedProductUsingAppPrice(product)
     || isMeltedTradeGroup(product.group_type)
     || isMetalCommodityGroup(product.group_type)
+    || usesQuantityTrade(product)
   ) {
     return base + fee
   }
 
   const withFee = base + fee
   return product.direct_price === 0
-    ? withFee * Number(product.amount ?? 0)
+    ? withFee * productPriceAmountFactor(product)
     : withFee
 }
 
@@ -138,7 +140,7 @@ export function getProductSellPrice(product: Product): number {
     return 0
   }
 
-  if (isMeltedProductUsingAppPrice(product) || isMeltedTradeGroup(product.group_type)) {
+  if (isMeltedProductUsingAppPrice(product) || isMeltedTradeGroup(product.group_type) || usesQuantityTrade(product)) {
     return base - Number(product.cash_fee_sell ?? 0)
   }