fix(stock): backfill transferred qty for existing pick lists

Pick Lists transferred before this feature have transferred_qty = 0 and
their Stock Entry rows carry no pick_list_item link, so the new
is_fully_transferred check would never fire and, with the old
duplicate-entry guard removed, they could be transferred again. Set
transferred_qty = picked_qty for non-Delivery submitted pick lists that
already have a linked Stock Entry so they stay completed and locked.

erpnext/patches.txt

@@ -488,4 +488,5 @@ execute:frappe.db.set_single_value("Accounts Settings", "pcv_job_timeout", 3600)
 erpnext.patches.v16_0.remove_mandatory_from_inv_dimension_fields
 erpnext.patches.v15_0.backfill_sla_link_filters_on_custom_field
 erpnext.patches.v15_0.backfill_sla_link_filters_on_docfield
-erpnext.patches.v16_0.crm_settings_handle_allowed_users_for_frappe_crm
+erpnext.patches.v16_0.crm_settings_handle_allowed_users_for_frappe_crm
+erpnext.patches.v16_0.backfill_pick_list_transferred_qty

erpnext/patches/v16_0/backfill_pick_list_transferred_qty.py

@@ -0,0 +1,58 @@
+import frappe
+from frappe.query_builder.functions import Sum
+from frappe.utils import flt
+
+
+def execute():
+	StockEntry = frappe.qb.DocType("Stock Entry")
+	StockEntryDetail = frappe.qb.DocType("Stock Entry Detail")
+
+	pick_lists = (
+		frappe.qb.from_(StockEntry)
+		.select(StockEntry.pick_list)
+		.distinct()
+		.where((StockEntry.pick_list.isnotnull()) & (StockEntry.docstatus == 1))
+	).run(pluck=True)
+
+	if not pick_lists:
+		return
+
+	rows = (
+		frappe.qb.from_(StockEntryDetail)
+		.join(StockEntry)
+		.on(StockEntryDetail.parent == StockEntry.name)
+		.select(
+			StockEntry.pick_list,
+			StockEntryDetail.item_code,
+			StockEntryDetail.s_warehouse,
+			Sum(StockEntryDetail.transfer_qty).as_("qty"),
+		)
+		.where((StockEntry.pick_list.isin(pick_lists)) & (StockEntry.docstatus == 1))
+		.groupby(StockEntry.pick_list, StockEntryDetail.item_code, StockEntryDetail.s_warehouse)
+	).run(as_dict=True)
+
+	transferred = {(r.pick_list, r.item_code, r.s_warehouse): flt(r.qty) for r in rows}
+
+	items = frappe.get_all(
+		"Pick List Item",
+		filters={"parent": ("in", pick_lists), "picked_qty": (">", 0)},
+		fields=["name", "parent", "item_code", "warehouse", "picked_qty"],
+		order_by="idx",
+	)
+
+	updates = {}
+	for row in items:
+		key = (row.parent, row.item_code, row.warehouse)
+		available = transferred.get(key, 0)
+		if available <= 0:
+			continue
+		qty = min(flt(row.picked_qty), available)
+		transferred[key] = available - qty
+		updates[row.name] = {"transferred_qty": qty}
+
+	if not updates:
+		return
+
+	frappe.db.auto_commit_on_many_writes = True
+	frappe.db.bulk_update("Pick List Item", updates)
+	frappe.db.auto_commit_on_many_writes = False