fix: preserve stock ageing on non-serial reconciliation

erpnext/stock/report/stock_ageing/stock_ageing.py

@@ -358,7 +358,7 @@ class FIFOSlots:
 		if row.voucher_type != "Stock Reconciliation":
 			return
 
-		if not row.batch_no or row.serial_no or row.serial_and_batch_bundle:
+		if row.has_serial_no and (not row.batch_no or row.serial_no or row.serial_and_batch_bundle):
 			if row.voucher_detail_no in self.stock_reco_voucher_wise_count:
 				# Legacy reconciliation with a single SLE has qty_after_transaction and
 				# stock_value_difference without an outward entry, so reset the queue first.
@@ -1083,6 +1083,7 @@ class FIFOSlots:
 				(doctype.voucher_type == "Stock Reconciliation")
 				& (doctype.docstatus < 2)
 				& (doctype.is_cancelled == 0)
+				& (item.has_serial_no == 1)
 			)
 			.groupby(doctype.voucher_detail_no)
 		)

erpnext/stock/report/stock_ageing/test_stock_ageing.py

@@ -195,6 +195,67 @@ class TestStockAgeing(FrappeTestCase):
 		self.assertEqual(queue[0][0], 20.0)
 		self.assertEqual(queue[1][0], 20.0)
 
+	def test_non_serial_stock_reco_decrease_preserves_ageing(self):
+		"""
+		Non-serial stock reconciliation should adjust FIFO by the balance delta.
+		Decreasing stock consumes old slots; increasing stock adds only the new qty.
+		"""
+
+		def make_sle(
+			posting_date,
+			voucher_type,
+			voucher_no,
+			actual_qty,
+			qty_after,
+			voucher_detail_no=None,
+			stock_value_difference=None,
+		):
+			stock_value_difference = actual_qty if stock_value_difference is None else stock_value_difference
+
+			return frappe._dict(
+				name="Flask Item",
+				item_name="Flask Item",
+				description="Flask Item",
+				item_group=None,
+				brand=None,
+				stock_uom="Nos",
+				actual_qty=actual_qty,
+				qty_after_transaction=qty_after,
+				stock_value_difference=stock_value_difference,
+				valuation_rate=1,
+				warehouse="WH 1",
+				posting_date=posting_date,
+				voucher_type=voucher_type,
+				voucher_no=voucher_no,
+				voucher_detail_no=voucher_detail_no,
+				has_serial_no=False,
+				has_batch_no=False,
+				serial_no=None,
+				batch_no=None,
+				serial_and_batch_bundle=None,
+			)
+
+		filters = frappe._dict(company="_Test Company", to_date="2026-02-15", ranges=["30", "60", "90"])
+		sle = [
+			make_sle("2025-11-30", "Stock Entry", "001", 100, 100),
+			make_sle("2025-12-31", "Stock Reconciliation", "002", 0, 60, "SRI-DECREASE", -40),
+			make_sle("2026-01-31", "Stock Reconciliation", "003", 0, 90, "SRI-INCREASE", 30),
+		]
+
+		fifo_slots = FIFOSlots(filters, sle)
+
+		def prepare_stock_reco_voucher_wise_count():
+			fifo_slots.stock_reco_voucher_wise_count = frappe._dict({"SRI-DECREASE": 100, "SRI-INCREASE": 60})
+
+		fifo_slots.prepare_stock_reco_voucher_wise_count = prepare_stock_reco_voucher_wise_count
+
+		slots = fifo_slots.generate()
+		queue = slots["Flask Item"]["fifo_queue"]
+		report_data = format_report_data(filters, slots, filters.to_date)
+
+		self.assertEqual(queue, [[60.0, "2025-11-30", 60.0], [30.0, "2026-01-31", 30.0]])
+		self.assertEqual(report_data[0][7:15], [30.0, 30.0, 0.0, 0.0, 60.0, 60.0, 0.0, 0.0])
+
 	def test_sequential_stock_reco_same_warehouse(self):
 		"""
 		Test back to back stock recos (same warehouse).