feat: add weighted products and refund workflows

frontend/src/app/(dashboard)/pos/page.tsx

@@ -33,6 +33,7 @@ import { useFormatCurrency } from '@/hooks/useFormatCurrency';
 import { useSupportTicketStatus } from '@/hooks/useSupportTicketStatus';
 import { useSupportDiagnosticsPreview } from '@/hooks/useSupportDiagnosticsPreview';
 import { getCurrencySymbol, getCountryByCode } from '@/lib/countries';
+import { resolveScannedProduct } from '@/lib/scale-barcode';
 import {
   buildAppendItemsFingerprint,
   clearAppendAttempt,
@@ -49,10 +50,6 @@ import {
 const PREPAID_ATTEMPT_STORAGE_KEY = 'flo.prepaid.checkout.attempt';
 const POSTPAID_ATTEMPT_STORAGE_KEY = 'flo.postpaid.order.attempt';
 
-function normalizeBarcode(value: string | null | undefined) {
-  return value?.trim() || '';
-}
-
 interface PostpaidAttempt {
   userId: string;
   fingerprint: string;
@@ -415,10 +412,10 @@ export default function POSPage() {
     || !!paymentBill || showCustomerPrompt || showPrepaidCheckout;
 
   useBarcodeScanner((code) => {
-    const normalizedCode = normalizeBarcode(code);
-    const product = products.find((p) => normalizeBarcode(p.barcode) === normalizedCode);
-    if (product) {
-      handleProductClick(product);
+    const scan = resolveScannedProduct(code, products);
+    if (scan) {
+      if (scan.scaleBarcode) cart.addItem(scan.product, scan.quantity);
+      else handleProductClick(scan.product);
     } else {
       toast.error(t('barcodeNotFound', { code }));
     }

frontend/src/app/(dashboard)/products/page.tsx

@@ -94,6 +94,7 @@ export default function ProductsPage() {
   const [addonList, setAddonList] = useState<{ id?: number | string; name: string; price: number; is_active?: boolean }[]>([]);
   const [form, setForm] = useState({
     name: '', category_id: '', price: '', cost_price: '', cb_percent: '', sku: '', barcode: '',
+    sale_unit: 'each' as Product['sale_unit'], allow_fractional_quantity: false, weight_precision: '3',
     tax_category_id: '', tax_behavior: 'country_default', description: '',
     track_inventory: false, stock_quantity: '0', low_stock_threshold: '5', is_active: true,
     tags: [] as string[],
@@ -238,6 +239,7 @@ export default function ProductsPage() {
   const resetForm = () => {
     setForm({
       name: '', category_id: '', price: '', cost_price: '', cb_percent: '', sku: '', barcode: '',
+      sale_unit: 'each', allow_fractional_quantity: false, weight_precision: '3',
       tax_category_id: '', tax_behavior: 'country_default', description: '',
       track_inventory: false, stock_quantity: '0', low_stock_threshold: '5', is_active: true,
       tags: [], customTag: '', addon_group_ids: [], image_url: null,
@@ -263,6 +265,9 @@ export default function ProductsPage() {
       cb_percent: product.cb_percent === null || product.cb_percent === undefined ? '' : String(product.cb_percent),
       sku: product.sku || '',
       barcode: product.barcode || '',
+      sale_unit: product.sale_unit || 'each',
+      allow_fractional_quantity: !!product.allow_fractional_quantity,
+      weight_precision: String(product.weight_precision ?? 3),
       tax_category_id: product.tax_category_id || '',
       tax_behavior: product.tax_behavior || 'country_default',
       description: product.description || '',
@@ -298,6 +303,9 @@ export default function ProductsPage() {
         cb_percent: cbPercentVal,
         sku: form.sku || null,
         barcode: form.barcode || null,
+        sale_unit: form.sale_unit,
+        allow_fractional_quantity: form.allow_fractional_quantity,
+        weight_precision: Number(form.weight_precision),
         tax_category_id: form.tax_category_id || null,
         tax_behavior: form.tax_category_id ? form.tax_behavior : 'country_default',
         description: form.description || null,
@@ -703,6 +711,48 @@ export default function ProductsPage() {
                   className="w-full px-3 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-brand outline-none font-mono" />
                 <p className="text-xs text-gray-400 mt-1">{t('fieldBarcodeHint')}</p>
               </div>
+              <div className="grid grid-cols-3 gap-4">
+                <div>
+                  <label className="block text-sm font-medium text-gray-700 mb-1">{t('fieldSaleUnit')}</label>
+                  <select
+                    value={form.sale_unit}
+                    onChange={(e) => {
+                      const saleUnit = e.target.value as Product['sale_unit'];
+                      setForm({
+                        ...form,
+                        sale_unit: saleUnit,
+                        allow_fractional_quantity: saleUnit === 'each' ? false : true,
+                      });
+                    }}
+                    className="w-full px-3 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-brand outline-none"
+                  >
+                    <option value="each">{t('saleUnitEach')}</option>
+                    <option value="kg">{t('saleUnitKg')}</option>
+                    <option value="g">{t('saleUnitG')}</option>
+                    <option value="lb">{t('saleUnitLb')}</option>
+                  </select>
+                </div>
+                <div>
+                  <label className="block text-sm font-medium text-gray-700 mb-1">{t('fieldWeightPrecision')}</label>
+                  <input
+                    type="number"
+                    min="0"
+                    max="4"
+                    value={form.weight_precision}
+                    onChange={(e) => setForm({ ...form, weight_precision: e.target.value })}
+                    className="w-full px-3 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-brand outline-none"
+                  />
+                </div>
+                <label className="flex items-center gap-2 pt-7">
+                  <input
+                    type="checkbox"
+                    checked={form.allow_fractional_quantity}
+                    onChange={(e) => setForm({ ...form, allow_fractional_quantity: e.target.checked })}
+                    className="rounded border-gray-300 text-brand focus:ring-brand"
+                  />
+                  <span className="text-sm text-gray-700">{t('fieldAllowFractionalQuantity')}</span>
+                </label>
+              </div>
               <div className="grid grid-cols-2 gap-4">
                 <div>
                   <label className="block text-sm font-medium text-gray-700 mb-1">{t('priceLabel', { currency })}<span className="text-red-500 ms-1">*</span></label>

frontend/src/components/pos/ProductGrid.tsx

@@ -11,6 +11,7 @@ import api from '@/lib/api';
 import { useTranslations } from 'use-intl';
 import { parseDbTimestamp } from '@/lib/utils';
 import { useFormatCurrency } from '@/hooks/useFormatCurrency';
+import { resolveScannedProduct } from '@/lib/scale-barcode';
 
 const CATEGORY_COLORS: Record<string, { bg: string; text: string; border: string; activeBg: string; activeText: string }> = {
   red: { bg: 'bg-red-50', text: 'text-red-700', border: 'border-red-200', activeBg: 'bg-red-500', activeText: 'text-white' },
@@ -37,10 +38,6 @@ function getCategoryColorClasses(color: string | null | undefined) {
   return CATEGORY_COLORS[color.toLowerCase()] || null;
 }
 
-function normalizeBarcode(value: string | null | undefined) {
-  return value?.trim() || '';
-}
-
 interface Props {
   categories: Category[];
   products: Product[];
@@ -90,9 +87,10 @@ export default function ProductGrid({
               // action into this field works regardless of typing speed.
               const trimmed = search.trim();
               if (!trimmed) return;
-              const match = products.find((p) => normalizeBarcode(p.barcode) === trimmed);
+              const match = resolveScannedProduct(trimmed, products);
               if (match) {
-                onProductClick(match);
+                if (match.scaleBarcode) cart.addItem(match.product, match.quantity);
+                else onProductClick(match.product);
                 setSearch('');
               }
             }}

frontend/src/lib/i18n/messages/en.json

@@ -824,16 +824,19 @@
     "fieldBarcode": "Barcode",
     "fieldBarcodeHint": "Scan this product at POS to add it to the cart directly.",
     "fieldBarcodePlaceholder": "Scan or type a barcode",
+    "fieldAllowFractionalQuantity": "Fractional quantity",
     "fieldCategory": "Category",
     "fieldCostPrice": "Cost Price",
     "fieldImage": "Product Image",
     "fieldLowStockThreshold": "Low Stock Threshold",
     "fieldName": "Name",
+    "fieldSaleUnit": "Sale unit",
     "fieldSku": "SKU",
     "fieldStock": "Current Stock",
     "fieldTags": "Tags",
     "fieldTaxType": "Tax Type",
     "fieldTrackInventory": "Track Inventory",
+    "fieldWeightPrecision": "Precision",
     "hiddenOnPos": "(Hidden on POS)",
     "imageCamera": "Camera",
     "imageCompressFailed": "Could not compress this image enough. Try a tighter crop or another image.",
@@ -865,6 +868,10 @@
     "optional": "Optional",
     "optionalTag": "Optional",
     "priceLabel": "Price ({currency})",
+    "saleUnitEach": "Each",
+    "saleUnitG": "g",
+    "saleUnitKg": "kg",
+    "saleUnitLb": "lb",
     "reassignAndDelete": "Products reassigned and category deleted",
     "required": "Required",
     "requiredSelection": "Required selection",

frontend/src/lib/i18n/messages/es.json

@@ -824,16 +824,19 @@
     "fieldBarcode": "Código de barras",
     "fieldBarcodeHint": "Escaneá este producto en el POS para agregarlo directamente al carrito.",
     "fieldBarcodePlaceholder": "Escaneá o escribí un código de barras",
+    "fieldAllowFractionalQuantity": "Cantidad fraccionaria",
     "fieldCategory": "Categoría",
     "fieldCostPrice": "Precio de costo",
     "fieldImage": "Imagen del producto",
     "fieldLowStockThreshold": "Umbral de Existencias Bajas",
     "fieldName": "Nombre",
+    "fieldSaleUnit": "Unidad de venta",
     "fieldSku": "SKU",
     "fieldStock": "Stock Actual",
     "fieldTags": "Etiquetas y Atributos",
     "fieldTaxType": "Tipo de impuesto",
     "fieldTrackInventory": "Llevar control de inventario",
+    "fieldWeightPrecision": "Precisión",
     "hiddenOnPos": "(Oculto en POS)",
     "imageCamera": "Cámara",
     "imageCompressFailed": "No se pudo comprimir lo suficiente esta imagen. Probá un recorte más ajustado u otra imagen.",
@@ -865,6 +868,10 @@
     "optional": "Opcional",
     "optionalTag": "Opcional",
     "priceLabel": "Precio ({currency})",
+    "saleUnitEach": "Unidad",
+    "saleUnitG": "g",
+    "saleUnitKg": "kg",
+    "saleUnitLb": "lb",
     "reassignAndDelete": "Productos reasignados y categoría eliminada",
     "required": "Obligatorio",
     "requiredSelection": "Selección obligatoria",

frontend/src/lib/i18n/messages/fa.json

@@ -824,16 +824,19 @@
     "fieldBarcode": "بارکد",
     "fieldBarcodeHint": "این کالا را در صندوق پویش کنید تا بی‌درنگ به سبد افزوده شود.",
     "fieldBarcodePlaceholder": "بارکد را پویش کنید یا بنویسید",
+    "fieldAllowFractionalQuantity": "مقدار کسری",
     "fieldCategory": "دسته",
     "fieldCostPrice": "بهای خرید",
     "fieldImage": "نگاره کالا",
     "fieldLowStockThreshold": "آستانه کمبود موجودی",
     "fieldName": "نام",
+    "fieldSaleUnit": "واحد فروش",
     "fieldSku": "شناسه کالا",
     "fieldStock": "موجودی کنونی",
     "fieldTags": "برچسب‌ها",
     "fieldTaxType": "گونه مالیات",
     "fieldTrackInventory": "پیگیری موجودی",
+    "fieldWeightPrecision": "دقت",
     "hiddenOnPos": "(پنهان در صندوق)",
     "imageCamera": "دوربین",
     "imageCompressFailed": "این تصویر به اندازه کافی فشرده نشد. برش فشرده‌تر یا تصویر دیگری را بیازمایید.",
@@ -865,6 +868,10 @@
     "optional": "اختیاری",
     "optionalTag": "اختیاری",
     "priceLabel": " ({currency}) قیمت ",
+    "saleUnitEach": "عدد",
+    "saleUnitG": "گرم",
+    "saleUnitKg": "کیلوگرم",
+    "saleUnitLb": "پوند",
     "reassignAndDelete": "کالاها دوباره دسته‌بندی شدند و دسته پاک شد",
     "required": "بایسته",
     "requiredSelection": "گزینش بایسته",

frontend/src/lib/i18n/messages/pt.json

@@ -824,16 +824,19 @@
     "fieldBarcode": "Código de barras",
     "fieldBarcodeHint": "Escanear este produto no PDV para adicioná-lo diretamente ao carrinho.",
     "fieldBarcodePlaceholder": "Escanear ou digitar um código de barras",
+    "fieldAllowFractionalQuantity": "Quantidade fracionária",
     "fieldCategory": "Categoria",
     "fieldCostPrice": "Preço de Custo",
     "fieldImage": "Imagem do Produto",
     "fieldLowStockThreshold": "Limite de Estoque Baixo",
     "fieldName": "Nome",
+    "fieldSaleUnit": "Unidade de venda",
     "fieldSku": "SKU",
     "fieldStock": "Estoque Atual",
     "fieldTags": "Etiquetas",
     "fieldTaxType": "Tipo de Imposto",
     "fieldTrackInventory": "Controlar Estoque",
+    "fieldWeightPrecision": "Precisão",
     "hiddenOnPos": "(Oculto no POS)",
     "imageCamera": "Câmera",
     "imageCompressFailed": "Não foi possível comprimir esta imagem o suficiente. Tente um recorte mais justo ou outra imagem.",
@@ -865,6 +868,10 @@
     "optional": "Opcional",
     "optionalTag": "Opcional",
     "priceLabel": "Preço ({currency})",
+    "saleUnitEach": "Unidade",
+    "saleUnitG": "g",
+    "saleUnitKg": "kg",
+    "saleUnitLb": "lb",
     "reassignAndDelete": "Produtos reatribuídos e categoria excluída",
     "required": "Obrigatório",
     "requiredSelection": "Seleção obrigatória",

frontend/src/lib/scale-barcode.ts

@@ -0,0 +1,74 @@
+import type { Product } from '@/lib/types';
+
+export type ScaleBarcodeConfig = {
+  prefix: string;
+  productDigits: number;
+  weightDigits: number;
+  unit: 'grams';
+};
+
+export type ParsedScaleBarcode = {
+  plu: string;
+  quantity: number;
+};
+
+export const DEFAULT_SCALE_BARCODE_CONFIG: ScaleBarcodeConfig = {
+  prefix: '21',
+  productDigits: 5,
+  weightDigits: 5,
+  unit: 'grams',
+};
+
+export function normalizeBarcode(value: unknown): string {
+  return typeof value === 'string' ? value.trim() : '';
+}
+
+export function parseScaleBarcode(
+  code: string,
+  config: ScaleBarcodeConfig = DEFAULT_SCALE_BARCODE_CONFIG,
+): ParsedScaleBarcode | null {
+  const normalized = normalizeBarcode(code);
+  const payloadLength = config.prefix.length + config.productDigits + config.weightDigits;
+  if (normalized.length < payloadLength || !normalized.startsWith(config.prefix) || !/^\d+$/.test(normalized)) {
+    return null;
+  }
+
+  const pluStart = config.prefix.length;
+  const plu = normalized.slice(pluStart, pluStart + config.productDigits);
+  const weightRaw = normalized.slice(pluStart + config.productDigits, payloadLength);
+  const grams = Number.parseInt(weightRaw, 10);
+  if (!Number.isSafeInteger(grams) || grams <= 0) return null;
+  return { plu, quantity: grams / 1000 };
+}
+
+function roundedQuantity(value: number, precision: number | null | undefined): number {
+  const digits = Number.isSafeInteger(precision) ? Math.min(Math.max(Number(precision), 0), 4) : 3;
+  return Number(value.toFixed(digits));
+}
+
+function quantityForProductUnit(parsed: ParsedScaleBarcode, product: Product): number | null {
+  if (product.sale_unit === 'kg') return roundedQuantity(parsed.quantity, product.weight_precision);
+  if (product.sale_unit === 'g') return roundedQuantity(parsed.quantity * 1000, product.weight_precision);
+  if (product.sale_unit === 'lb') return roundedQuantity(parsed.quantity / 0.45359237, product.weight_precision);
+  return null;
+}
+
+export function resolveScannedProduct(
+  code: string,
+  products: Product[],
+): { product: Product; quantity: number; scaleBarcode: ParsedScaleBarcode | null } | null {
+  const normalizedCode = normalizeBarcode(code);
+  const exact = products.find((product) => normalizeBarcode(product.barcode) === normalizedCode);
+  if (exact) return { product: exact, quantity: 1, scaleBarcode: null };
+
+  const parsed = parseScaleBarcode(normalizedCode);
+  if (!parsed) return null;
+  const product = products.find((candidate) => {
+    if (!candidate.allow_fractional_quantity) return false;
+    if (candidate.sale_unit !== 'kg' && candidate.sale_unit !== 'g' && candidate.sale_unit !== 'lb') return false;
+    return normalizeBarcode(candidate.barcode) === parsed.plu || normalizeBarcode(candidate.sku) === parsed.plu;
+  });
+  if (!product) return null;
+  const quantity = quantityForProductUnit(parsed, product);
+  return quantity ? { product, quantity, scaleBarcode: parsed } : null;
+}

frontend/src/lib/types.ts

@@ -62,6 +62,9 @@ export interface Product {
   name: string;
   sku: string | null;
   barcode: string | null;
+  sale_unit: 'each' | 'kg' | 'g' | 'lb';
+  allow_fractional_quantity: boolean;
+  weight_precision: number;
   description: string | null;
   price: number;
   cost_price: number | null;