fix: rescale batch FIFO slot values on stock reconciliation

Batch items take the batch-slot path, which mirrors the same value
arithmetic: the reco's incoming entry dumps the revaluation remainder
on one slot. Rescale each reconciled batch's slots at its post-reco
rate (stock_value_difference / qty of the incoming bundle entry).

erpnext/stock/report/stock_ageing/stock_ageing.py

@@ -370,7 +370,7 @@ class FIFOSlots:
 				row, fifo_queue, transferred_item_key, serial_nos, batch_nos, from_end
 			)
 
-		self._revalue_stock_reconciliation_slots(row, fifo_queue)
+		self._revalue_stock_reconciliation_slots(row, fifo_queue, batch_nos)
 		self._update_balances(row, key)
 		self._trim_serial_fifo_queue(row, key, fifo_queue)
 
@@ -394,14 +394,29 @@ class FIFOSlots:
 		# Stock reconciliation stores the final balance; FIFO needs the movement delta.
 		row.actual_qty = flt(row.qty_after_transaction) - flt(prev_balance_qty)
 
-	def _revalue_stock_reconciliation_slots(self, row: dict, fifo_queue: list) -> None:
-		if row.voucher_type != "Stock Reconciliation" or row.has_serial_no or row.has_batch_no:
+	def _revalue_stock_reconciliation_slots(self, row: dict, fifo_queue: list, batch_nos: list) -> None:
+		if row.voucher_type != "Stock Reconciliation" or row.has_serial_no:
+			return
+
+		if row.has_batch_no:
+			if flt(row.actual_qty) > 0:
+				self._revalue_reconciled_batch_slots(fifo_queue, batch_nos)
 			return
 
 		for slot in fifo_queue:
 			if is_qty_slot(slot):
 				slot[FIFO_VALUE_INDEX] = flt(slot[FIFO_QTY_INDEX] * flt(row.valuation_rate))
 
+	def _revalue_reconciled_batch_slots(self, fifo_queue: list, batch_nos: list) -> None:
+		for batch_no, _use_batchwise_valuation, qty, stock_value_difference in batch_nos:
+			if not flt(qty):
+				continue
+
+			rate = flt(stock_value_difference) / flt(qty)
+			for slot in fifo_queue:
+				if is_batch_slot(slot) and slot[BATCH_SLOT_BATCH_INDEX] == batch_no:
+					slot[BATCH_SLOT_VALUE_INDEX] = flt(slot[BATCH_SLOT_QTY_INDEX] * rate)
+
 	def _get_serial_and_batch_nos(
 		self, row: dict, bundle_wise_serial_nos: dict, bundle_wise_batch_nos: dict
 	) -> tuple[list, list]:

erpnext/stock/report/stock_ageing/test_stock_ageing.py

@@ -464,6 +464,56 @@ class TestStockAgeing(ERPNextTestSuite):
 
 		self.assertEqual(queue, [[10.0, "2021-12-01", 20.0], [2.0, "2021-12-02", 4.0]])
 
+	def test_batch_stock_reco_revaluation_rescales_slot_values(self):
+		"Ledger (same wh, batch B): [+10 @ 100, reco out >> 0, reco in >> 12 @ 2]"
+		from erpnext.stock.doctype.item.test_item import make_item
+
+		item_code = make_item(
+			"Test Stock Ageing Batch Reco Revaluation",
+			{"is_stock_item": 1, "has_batch_no": 1, "valuation_method": "FIFO"},
+		).name
+
+		batch_no = "SA-RECO-REVALUE-BATCH"
+		if not frappe.db.exists("Batch", batch_no):
+			frappe.get_doc({"doctype": "Batch", "batch_id": batch_no, "item": item_code}).insert(
+				ignore_permissions=True
+			)
+		frappe.db.set_value("Batch", batch_no, "use_batchwise_valuation", 1)
+
+		def make_sle(posting_date, voucher_type, voucher_no, actual_qty, qty_after, stock_value_difference):
+			return frappe._dict(
+				name=item_code,
+				actual_qty=actual_qty,
+				qty_after_transaction=qty_after,
+				stock_value_difference=stock_value_difference,
+				valuation_rate=abs(stock_value_difference / actual_qty),
+				warehouse="WH 1",
+				posting_date=posting_date,
+				voucher_type=voucher_type,
+				voucher_no=voucher_no,
+				has_serial_no=False,
+				has_batch_no=True,
+				serial_no=None,
+				batch_no=batch_no,
+			)
+
+		sle = [
+			make_sle("2021-12-01", "Stock Entry", "001", 10, 10, 1000),
+			make_sle("2021-12-02", "Stock Reconciliation", "002", -10, 0, -1000),
+			make_sle("2021-12-02", "Stock Reconciliation", "002", 12, 12, 24),
+		]
+
+		slots = FIFOSlots(self.filters, sle).generate()
+		queue = slots[item_code]["fifo_queue"]
+
+		self.assertEqual(
+			queue,
+			[
+				[batch_no, 1, 10.0, "2021-12-01", 20.0],
+				[batch_no, 1, 2.0, "2021-12-02", 4.0],
+			],
+		)
+
 	def test_sequential_stock_reco_same_warehouse(self):
 		"""
 		Test back to back stock recos (same warehouse).