Custom duplicate bug

modules/purchase_trade/purchase.py

@@ -2148,6 +2148,8 @@ class Line(metaclass=PoolMeta):
             return
         if values.get('estimated_date') is None:
             values['estimated_date'] = []
+        elif isinstance(values['estimated_date'], tuple):
+            values['estimated_date'] = list(values['estimated_date'])
         values['estimated_date'].append(('create', [{
             'trigger': 'bldate',
             'estimated_date': estimated_date,

modules/purchase_trade/sale.py

@@ -1975,6 +1975,8 @@ class SaleLine(metaclass=PoolMeta):
             return
         if values.get('estimated_date') is None:
             values['estimated_date'] = []
+        elif isinstance(values['estimated_date'], tuple):
+            values['estimated_date'] = list(values['estimated_date'])
         values['estimated_date'].append(('create', [{
             'trigger': 'bldate',
             'estimated_date': estimated_date,

modules/purchase_trade/tests/test_module.py

@@ -4409,6 +4409,34 @@ class PurchaseTradeTestCase(ModuleTestCase):
             'estimated_date': datetime.date(2026, 5, 1),
         }])])
 
+    def test_purchase_and_sale_line_default_estimated_bl_date_accepts_tuple(self):
+        'new lines normalize tuple estimated date commands before appending'
+        PurchaseLine = Pool().get('purchase.line')
+        SaleLine = Pool().get('sale.line')
+        period = Mock(beg_date=datetime.date(2026, 5, 1))
+        existing = ('create', [{
+            'trigger': 'other',
+            'estimated_date': datetime.date(2026, 5, 9),
+        }])
+        purchase_values = {
+            'del_period': period,
+            'estimated_date': (existing,),
+            }
+        sale_values = {
+            'del_period': period,
+            'estimated_date': (existing,),
+            }
+
+        PurchaseLine._set_default_estimated_bl_date_values(purchase_values)
+        SaleLine._set_default_estimated_bl_date_values(sale_values)
+
+        expected = [existing, ('create', [{
+            'trigger': 'bldate',
+            'estimated_date': datetime.date(2026, 5, 1),
+        }])]
+        self.assertEqual(purchase_values['estimated_date'], expected)
+        self.assertEqual(sale_values['estimated_date'], expected)
+
     def test_purchase_line_reporting_parent_fields_and_counts(self):
         'purchase line reporting fields mirror parent values and relation counts'
         PurchaseLine = Pool().get('purchase.line')