From b2973fc2539b5810c5ac7b59afc6bf38a7400099 Mon Sep 17 00:00:00 2001
From: Sourav Singh <ascra@ASUS-EXPERTBOOK-P3405CVA.lan>
Date: Sun, 31 May 2026 05:22:43 +0530
Subject: [PATCH] fix(cart): keep separate lines per batch for batch-tracked
 items

Cart merge matched item_code + UOM only, so a second batch overwrote the
first line and only one batch reached the Sales Invoice. Match lines by
batch_no, add ERPNext-aligned auto-allocation for multi-batch qty, and
scope cart update/remove to the correct batch line.

Fixes #266
---
 POS/src/components/sale/BatchSerialDialog.vue | 108 ++++++++++++++-
 POS/src/components/sale/InvoiceCart.vue       |  16 +--
 POS/src/composables/useInvoice.js             |  54 ++++++--
 POS/src/pages/POSSale.vue                     |  36 ++++-
 POS/src/stores/posCart.js                     |  35 +++--
 pos_next/api/items.py                         | 124 ++++++++++++++++++
 6 files changed, 337 insertions(+), 36 deletions(-)

diff --git a/POS/src/components/sale/BatchSerialDialog.vue b/POS/src/components/sale/BatchSerialDialog.vue
index f4f09899a..424853e91 100644
--- a/POS/src/components/sale/BatchSerialDialog.vue
+++ b/POS/src/components/sale/BatchSerialDialog.vue
@@ -29,8 +29,32 @@
 
 				<!-- Batch Selection -->
 				<div v-if="item?.has_batch_no">
+					<div v-if="requestedQty > 1" class="mb-3 rounded-lg border border-blue-200 bg-blue-50 p-3">
+						<div class="flex flex-wrap items-center justify-between gap-2">
+							<div class="text-sm text-gray-700">
+								<span class="font-medium">{{ __('Requested') }}:</span> {{ requestedQty }}
+								<span class="mx-2 text-gray-400">|</span>
+								<span class="font-medium">{{ __('Available') }}:</span> {{ totalAvailableQty }}
+								<span v-if="availableBatches.length" class="text-gray-500">
+									({{ __("{0} batches", [availableBatches.length]) }})
+								</span>
+							</div>
+							<Button
+								v-if="canAutoAllocate"
+								variant="solid"
+								size="sm"
+								:loading="isAllocating"
+								@click="autoAllocateBatches"
+							>
+								{{ __('Auto Allocate') }}
+							</Button>
+						</div>
+						<p v-if="allocationError" class="mt-2 text-xs text-red-600">{{ allocationError }}</p>
+					</div>
+
 					<label class="block text-sm font-medium text-gray-700 mb-2">
 						{{ __('Select Batch Number') }}
+						<span class="font-normal text-gray-500">({{ __('optional if using Auto Allocate') }})</span>
 					</label>
 					<div class="flex flex-col gap-2 max-h-80 overflow-y-auto">
 						<div
@@ -54,6 +78,9 @@
 										<span v-if="batch.expiry_date" class="text-xs text-gray-600">
 											{{ __('Exp: {0}', [formatDate(batch.expiry_date)]) }}
 										</span>
+										<span v-if="requestedQty > 1 && selectedBatch?.batch_no === batch.batch_no && batch.qty < requestedQty" class="text-xs text-amber-600">
+											{{ __('Max {0} from this batch', [batch.qty]) }}
+										</span>
 									</div>
 								</div>
 								<div v-if="selectedBatch?.batch_no === batch.batch_no" class="flex-shrink-0">
@@ -188,7 +215,7 @@
 				<Button
 					variant="solid"
 					@click="handleConfirm"
-					:disabled="!isValid"
+					:disabled="!isValid || isAllocating"
 				>
 					{{ __('Confirm') }}
 				</Button>
@@ -198,7 +225,7 @@
 </template>
 
 <script setup>
-import { Button, Dialog, createResource } from "frappe-ui"
+import { Button, Dialog, createResource, call } from "frappe-ui"
 import { computed, ref, watch } from "vue"
 import { useSerialNumberStore } from "@/stores/serialNumber"
 import { usePOSCartStore } from "@/stores/posCart"
@@ -230,6 +257,22 @@ const availableSerials = ref([])
 const selectedBatch = ref(null)
 const selectedSerials = ref([])
 const serialSearchQuery = ref("")
+const isAllocating = ref(false)
+const allocationError = ref("")
+
+const requestedQty = computed(() => Math.max(1, Math.round(Number(props.quantity) || 1)))
+
+const totalAvailableQty = computed(() =>
+	availableBatches.value.reduce((sum, batch) => sum + (batch.qty || 0), 0),
+)
+
+const canAutoAllocate = computed(() => {
+	return (
+		requestedQty.value > 0 &&
+		totalAvailableQty.value >= requestedQty.value &&
+		availableBatches.value.length > 0
+	)
+})
 
 // Computed: Available batches with cart quantities subtracted
 const availableBatches = computed(() => {
@@ -308,7 +351,13 @@ const filteredSerials = computed(() => {
 
 const isValid = computed(() => {
 	if (props.item?.has_batch_no) {
-		return selectedBatch.value !== null
+		if (!selectedBatch.value) {
+			return false
+		}
+		if (requestedQty.value > (selectedBatch.value.qty || 0)) {
+			return false
+		}
+		return true
 	}
 	if (props.item?.has_serial_no) {
 		// Valid if at least one serial is selected
@@ -391,11 +440,62 @@ function clearAllSerials() {
 	selectedSerials.value = []
 }
 
+function getConsumedBatchesFromCart() {
+	return cartStore.invoiceItems
+		.filter(
+			(cartItem) =>
+				cartItem.item_code === props.item?.item_code && cartItem.batch_no,
+		)
+		.map((cartItem) => ({
+			batch_no: cartItem.batch_no,
+			qty: (cartItem.quantity || 0) * (cartItem.conversion_factor || 1),
+		}))
+}
+
+async function autoAllocateBatches() {
+	if (!props.item?.item_code || !props.warehouse) {
+		return
+	}
+
+	allocationError.value = ""
+	isAllocating.value = true
+
+	try {
+		const segments = await call("pos_next.api.items.get_batch_allocation", {
+			item_code: props.item.item_code,
+			warehouse: props.warehouse,
+			qty: requestedQty.value,
+			consumed_batches: getConsumedBatchesFromCart(),
+		})
+
+		if (!segments?.length) {
+			allocationError.value = __("No batches could be allocated for the requested quantity.")
+			return
+		}
+
+		emit("batch-serial-selected", { segments })
+		show.value = false
+	} catch (error) {
+		allocationError.value =
+			error?.messages?.[0] || error?.message || __("Failed to allocate batches.")
+	} finally {
+		isAllocating.value = false
+	}
+}
+
 function handleConfirm() {
 	const result = {}
 
 	if (props.item?.has_batch_no && selectedBatch.value) {
+		if (requestedQty.value > (selectedBatch.value.qty || 0)) {
+			allocationError.value = __(
+				"Requested quantity ({0}) exceeds selected batch quantity ({1}). Use Auto Allocate for multiple batches.",
+				[requestedQty.value, selectedBatch.value.qty || 0],
+			)
+			return
+		}
 		result.batch_no = selectedBatch.value.batch_no
+		result.expiry_date = selectedBatch.value.expiry_date
 	}
 
 	if (props.item?.has_serial_no) {
@@ -416,6 +516,8 @@ function resetSelection() {
 	selectedSerials.value = []
 	serialSearchQuery.value = ""
 	warehouseBatches.value = []
+	allocationError.value = ""
+	isAllocating.value = false
 	// Don't clear availableSerials - it's managed by the store cache
 }
 
diff --git a/POS/src/components/sale/InvoiceCart.vue b/POS/src/components/sale/InvoiceCart.vue
index d91835154..8ea5cdb20 100644
--- a/POS/src/components/sale/InvoiceCart.vue
+++ b/POS/src/components/sale/InvoiceCart.vue
@@ -743,7 +743,7 @@
 			<div v-else class="flex flex-col gap-0.5 sm:gap-1">
 				<div
 					v-for="(item, index) in sortedItems"
-					:key="item.item_code + '-' + (item.uom || '') + (item.is_free_item ? '-free' : '')"
+					:key="item.item_code + '-' + (item.uom || '') + (item.batch_no ? '-' + item.batch_no : '') + (item.is_free_item ? '-free' : '')"
 					@click="item.is_free_item ? null : openEditDialog(item)"
 					:class="[
 						'border rounded-md p-1.5 sm:p-2 transition-all duration-200',
@@ -838,7 +838,7 @@
 								<button
 									v-if="!item.is_free_item"
 									type="button"
-									@click.stop="$emit('remove-item', item.item_code, item.uom)"
+									@click.stop="$emit('remove-item', item.item_code, item.uom, item.batch_no)"
 									class="text-gray-400 hover:text-red-600 active:text-red-700 transition-colors flex-shrink-0 p-0.5 -m-0.5 touch-manipulation active:scale-90"
 									:aria-label="__('Remove {0}', [item.item_name])"
 									:title="__('Remove item')"
@@ -1345,7 +1345,7 @@ const props = defineProps({
  */
 const emit = defineEmits([
 	"update-quantity", // (itemCode, newQty, uom?) - Update item quantity
-	"remove-item", // (itemCode, uom?) - Remove item from cart
+	"remove-item", // (itemCode, uom?, batchNo?) - Remove item from cart
 	"select-customer", // (customer) - Select/change customer
 	"edit-customer", // (customer) - Open edit customer dialog
 	"create-customer", // (searchText) - Open create customer dialog
@@ -1810,7 +1810,7 @@ function incrementQuantity(item) {
 
 	const step = getSmartStep(item.quantity);
 	const newQty = Math.round((item.quantity + step) * 10000) / 10000;
-	emit("update-quantity", item.item_code, newQty, item.uom);
+	emit("update-quantity", item.item_code, newQty, item.uom, item.batch_no);
 }
 
 /**
@@ -1828,9 +1828,9 @@ function decrementQuantity(item) {
 
 	if (newQty <= 0) {
 		// If quantity would be 0 or negative, remove the item
-		emit("remove-item", item.item_code, item.uom);
+		emit("remove-item", item.item_code, item.uom, item.batch_no);
 	} else {
-		emit("update-quantity", item.item_code, newQty, item.uom);
+		emit("update-quantity", item.item_code, newQty, item.uom, item.batch_no);
 	}
 }
 
@@ -1852,7 +1852,7 @@ function updateQuantity(item, value) {
 	if (isNaN(qty)) return;
 
 	// If quantity is zero or negative, remove the item from the cart
-	if (qty <= 0) return emit("remove-item", item.item_code, item.uom);
+	if (qty <= 0) return emit("remove-item", item.item_code, item.uom, item.batch_no);
 
 	// For positive numbers, update quantity immediately (no rounding here while typing)
 	emit("update-quantity", item.item_code, qty, item.uom);
@@ -1870,7 +1870,7 @@ function handleQuantityBlur(item) {
 	// When user leaves the input field, round and validate
 	if (!item.quantity || item.quantity <= 0) {
 		// If quantity is 0 or invalid, remove the item
-		emit("remove-item", item.item_code, item.uom);
+		emit("remove-item", item.item_code, item.uom, item.batch_no);
 	} else {
 		// Round to 4 decimal places for consistency
 		const roundedQty = Math.round(item.quantity * 10000) / 10000;
diff --git a/POS/src/composables/useInvoice.js b/POS/src/composables/useInvoice.js
index 87d26f303..840875f75 100644
--- a/POS/src/composables/useInvoice.js
+++ b/POS/src/composables/useInvoice.js
@@ -218,11 +218,21 @@ export function useInvoice() {
 	})
 
 	// Actions
-	function addItem(item, quantity = 1) {
+	function findMatchingCartItem(item) {
 		const itemUom = item.uom || item.stock_uom
-		const existingItem = invoiceItems.value.find(
-			(i) => i.item_code === item.item_code && i.uom === itemUom,
-		)
+		return invoiceItems.value.find((i) => {
+			if (i.item_code !== item.item_code || i.uom !== itemUom) {
+				return false
+			}
+			if (item.has_batch_no || i.has_batch_no) {
+				return (i.batch_no || "") === (item.batch_no || "")
+			}
+			return true
+		})
+	}
+
+	function addItem(item, quantity = 1) {
+		const existingItem = findMatchingCartItem(item)
 
 		if (existingItem) {
 			// Store old values before update for incremental cache adjustment
@@ -316,11 +326,27 @@ export function useInvoice() {
 	 *                            If provided, only removes the item with matching item_code AND uom.
 	 *                            If null, removes the first item matching item_code.
 	 */
-	function removeItem(itemCode, uom = null) {
+	function matchesCartLine(i, itemCode, uom, batchNo) {
+		if (i.item_code !== itemCode) {
+			return false
+		}
+		if (uom && i.uom !== uom) {
+			return false
+		}
+		if (batchNo !== undefined && batchNo !== null) {
+			return (i.batch_no || "") === (batchNo || "")
+		}
+		if (i.has_batch_no && batchNo === undefined) {
+			return false
+		}
+		return true
+	}
+
+	function removeItem(itemCode, uom = null, batchNo = undefined) {
 		let itemToRemove
-		if (uom) {
-			itemToRemove = invoiceItems.value.find(
-				(i) => i.item_code === itemCode && i.uom === uom,
+		if (uom || batchNo !== undefined) {
+			itemToRemove = invoiceItems.value.find((i) =>
+				matchesCartLine(i, itemCode, uom, batchNo),
 			)
 		} else {
 			itemToRemove = invoiceItems.value.find((i) => i.item_code === itemCode)
@@ -343,9 +369,9 @@ export function useInvoice() {
 			}
 		}
 
-		if (uom) {
+		if (uom || batchNo !== undefined) {
 			invoiceItems.value = invoiceItems.value.filter(
-				(i) => !(i.item_code === itemCode && i.uom === uom),
+				(i) => !matchesCartLine(i, itemCode, uom, batchNo),
 			)
 		} else {
 			invoiceItems.value = invoiceItems.value.filter(
@@ -362,11 +388,11 @@ export function useInvoice() {
 	 *                            If provided, only updates the item with matching item_code AND uom.
 	 *                            If null, updates the first item matching item_code.
 	 */
-	function updateItemQuantity(itemCode, quantity, uom = null) {
+	function updateItemQuantity(itemCode, quantity, uom = null, batchNo = undefined) {
 		let item
-		if (uom) {
-			item = invoiceItems.value.find(
-				(i) => i.item_code === itemCode && i.uom === uom,
+		if (uom || batchNo !== undefined) {
+			item = invoiceItems.value.find((i) =>
+				matchesCartLine(i, itemCode, uom, batchNo),
 			)
 		} else {
 			item = invoiceItems.value.find((i) => i.item_code === itemCode)
diff --git a/POS/src/pages/POSSale.vue b/POS/src/pages/POSSale.vue
index 1bb9ad508..d57805409 100644
--- a/POS/src/pages/POSSale.vue
+++ b/POS/src/pages/POSSale.vue
@@ -370,7 +370,8 @@
 								:warehouses="profileWarehouses"
 								@update-quantity="cartStore.updateItemQuantity"
 								@remove-item="
-									(itemCode, uom) => cartStore.removeItem(itemCode, uom)
+									(itemCode, uom, batchNo) =>
+										cartStore.removeItem(itemCode, uom, batchNo)
 								"
 								@select-customer="handleCustomerSelected"
 								@create-customer="handleCreateCustomer"
@@ -2477,6 +2478,39 @@ async function handleApplyOffer(offer) {
 }
 
 function handleBatchSerialSelected(batchSerial) {
+	if (!cartStore.pendingItem) {
+		return;
+	}
+
+	if (batchSerial.segments?.length) {
+		const itemName = cartStore.pendingItem.item_name;
+		try {
+			for (const segment of batchSerial.segments) {
+				const itemToAdd = {
+					...cartStore.pendingItem,
+					batch_no: segment.batch_no,
+					expiry_date: segment.expiry_date,
+				};
+				cartStore.addItem(
+					itemToAdd,
+					segment.qty,
+					false,
+					shiftStore.currentProfile,
+				);
+			}
+			cartStore.clearPendingItem();
+			showSuccess(
+				__("{0} added to cart ({1} batches)", [
+					itemName,
+					batchSerial.segments.length,
+				]),
+			);
+		} catch (error) {
+			showError(error.message);
+		}
+		return;
+	}
+
 	if (cartStore.pendingItem) {
 		// Use quantity from batchSerial if provided (for multiple serial numbers), otherwise use pendingItemQty
 		const qty = batchSerial.quantity || cartStore.pendingItemQty;
diff --git a/POS/src/stores/posCart.js b/POS/src/stores/posCart.js
index 2f9ed5b9a..9d636eab2 100644
--- a/POS/src/stores/posCart.js
+++ b/POS/src/stores/posCart.js
@@ -175,11 +175,17 @@ export const usePOSCartStore = defineStore("posCart", () => {
 	// Actions
 	function addItem(item, qty = 1, _autoAdd = false, currentProfile = null) {
 		if (currentProfile && settingsStore.shouldEnforceStockValidation() && shouldValidateItemStock(item)) {
-			// Account for quantity already in the cart for this item
+			// Account for quantity already in the cart (per batch when batch-tracked)
 			const itemUom = item.uom || item.stock_uom
-			const existing = invoiceItems.value.find(
-				(i) => i.item_code === item.item_code && i.uom === itemUom,
-			)
+			const existing = invoiceItems.value.find((i) => {
+				if (i.item_code !== item.item_code || i.uom !== itemUom) {
+					return false
+				}
+				if (item.has_batch_no || i.has_batch_no) {
+					return (i.batch_no || "") === (item.batch_no || "")
+				}
+				return true
+			})
 			const totalQty = (existing ? existing.quantity : 0) + qty
 			const warehouse = item.warehouse || currentProfile.warehouse
 
@@ -197,12 +203,21 @@ export const usePOSCartStore = defineStore("posCart", () => {
 	 * Wraps useInvoice.updateItemQuantity to enforce stock limits
 	 * when the user clicks +/- or types a new quantity.
 	 */
-	function updateItemQuantity(itemCode, quantity, uom = null) {
-		const item = uom
-			? invoiceItems.value.find((i) => i.item_code === itemCode && i.uom === uom)
-			: invoiceItems.value.find((i) => i.item_code === itemCode)
+	function updateItemQuantity(itemCode, quantity, uom = null, batchNo = undefined) {
+		const item =
+			uom || batchNo !== undefined
+				? invoiceItems.value.find((i) => {
+						if (i.item_code !== itemCode) return false
+						if (uom && i.uom !== uom) return false
+						if (batchNo !== undefined && batchNo !== null) {
+							return (i.batch_no || "") === (batchNo || "")
+						}
+						if (i.has_batch_no && batchNo === undefined) return false
+						return true
+					})
+				: invoiceItems.value.find((i) => i.item_code === itemCode)
 
-		if (!item) return baseUpdateItemQuantity(itemCode, quantity, uom)
+		if (!item) return baseUpdateItemQuantity(itemCode, quantity, uom, batchNo)
 
 		const newQty = Number.parseFloat(quantity) || 1
 
@@ -215,7 +230,7 @@ export const usePOSCartStore = defineStore("posCart", () => {
 			}
 		}
 
-		baseUpdateItemQuantity(itemCode, quantity, uom)
+		baseUpdateItemQuantity(itemCode, quantity, uom, batchNo)
 	}
 
 	function clearCart() {
diff --git a/pos_next/api/items.py b/pos_next/api/items.py
index d2dc2acfc..f90c88f6f 100644
--- a/pos_next/api/items.py
+++ b/pos_next/api/items.py
@@ -1804,6 +1804,130 @@ def get_item_details(item_code, pos_profile, customer=None, qty=1, uom=None):  #
 		frappe.throw(_("Error fetching item details: {0}").format(str(e)))
 
 
+@frappe.whitelist()
+def get_batch_allocation(item_code, warehouse, qty, posting_date=None, consumed_batches=None):
+	"""Split requested qty across batches using ERPNext Stock Settings (FIFO / Expiry).
+
+	Uses ``get_auto_batch_nos`` and ``get_qty_based_available_batches`` — same path as
+	auto Serial and Batch Bundle creation on outward stock transactions.
+	"""
+	from erpnext.stock.doctype.batch.batch import get_available_batches
+	from erpnext.stock.doctype.serial_and_batch_bundle.serial_and_batch_bundle import (
+		get_auto_batch_nos,
+		get_qty_based_available_batches,
+	)
+	from frappe.utils import now_datetime
+
+	qty = flt(qty)
+	if qty <= 0:
+		return []
+
+	if not item_code or not warehouse:
+		frappe.throw(_("Item Code and Warehouse are required"))
+
+	frappe.has_permission("Item", ptype="read", doc=item_code, throw=True)
+	frappe.has_permission("Warehouse", ptype="read", doc=warehouse, throw=True)
+
+	item = frappe.db.get_value(
+		"Item",
+		item_code,
+		["has_batch_no", "has_serial_no", "disabled"],
+		as_dict=True,
+	)
+	if not item or item.disabled:
+		frappe.throw(_("Invalid Item {0}").format(item_code))
+	if not item.has_batch_no or item.has_serial_no:
+		frappe.throw(_("Batch allocation applies only to batch items without serial numbers"))
+
+	consumed_by_batch = {}
+	if consumed_batches:
+		if isinstance(consumed_batches, str):
+			consumed_batches = json.loads(consumed_batches)
+		if not isinstance(consumed_batches, list):
+			frappe.throw(_("Invalid consumed_batches payload"))
+		for row in consumed_batches:
+			if not isinstance(row, dict):
+				continue
+			batch_no = row.get("batch_no")
+			if not batch_no:
+				continue
+			consumed_by_batch[batch_no] = consumed_by_batch.get(batch_no, 0) + flt(row.get("qty"))
+
+	if not consumed_by_batch:
+		batchwise_qty = get_available_batches(
+			frappe._dict(
+				{
+					"item_code": item_code,
+					"warehouse": warehouse,
+					"qty": qty,
+					"based_on": frappe.db.get_single_value(
+						"Stock Settings", "pick_serial_and_batch_based_on"
+					)
+					or "FIFO",
+					"posting_datetime": now_datetime(),
+				}
+			)
+		)
+		allocated = [
+			frappe._dict({"batch_no": batch_no, "qty": batch_qty})
+			for batch_no, batch_qty in batchwise_qty.items()
+		]
+	else:
+		kwargs = frappe._dict(
+			{
+				"item_code": item_code,
+				"warehouse": warehouse,
+				"qty": 0,
+				"based_on": frappe.db.get_single_value(
+					"Stock Settings", "pick_serial_and_batch_based_on"
+				)
+				or "FIFO",
+				"posting_datetime": now_datetime(),
+			}
+		)
+
+		available_batches = get_auto_batch_nos(kwargs) or []
+		for batch in available_batches:
+			batch.qty = flt(batch.qty) - flt(consumed_by_batch.get(batch.batch_no, 0))
+		precision = frappe.get_precision("Stock Ledger Entry", "actual_qty")
+		available_batches = [d for d in available_batches if flt(d.qty, precision) > 0]
+		allocated = get_qty_based_available_batches(available_batches, qty)
+	if not allocated:
+		frappe.throw(
+			_("Insufficient batch stock for {0} in {1}. Requested {2}.").format(
+				frappe.bold(item_code), frappe.bold(warehouse), frappe.bold(qty)
+			),
+			title=_("Insufficient Stock"),
+		)
+
+	allocated_total = sum(flt(row.qty) for row in allocated)
+	precision = frappe.get_precision("Stock Ledger Entry", "actual_qty")
+	if flt(allocated_total, precision) + 1e-9 < flt(qty, precision):
+		frappe.throw(
+			_("Only {0} available across batches for {1} in {2}. Requested {3}.").format(
+				frappe.bold(allocated_total),
+				frappe.bold(item_code),
+				frappe.bold(warehouse),
+				frappe.bold(qty),
+			),
+			title=_("Insufficient Stock"),
+		)
+
+	segments = []
+	for row in allocated:
+		batch_doc = frappe.get_cached_doc("Batch", row.batch_no)
+		segments.append(
+			{
+				"batch_no": row.batch_no,
+				"qty": flt(row.qty),
+				"expiry_date": batch_doc.expiry_date,
+				"manufacturing_date": batch_doc.manufacturing_date,
+			}
+		)
+
+	return segments
+
+
 @frappe.whitelist()
 def get_item_groups(pos_profile):
 	"""Get item groups configured in POS Profile with hierarchy info for filtering."""