[IMP] sale_stock_warehouse_multicompany: security

Allow to validate a picking linked to a SO of another company without
requiring enabling access to that company

sale_stock_warehouse_multicompany/models/__init__.py

@@ -2,3 +2,4 @@
 from . import sale_order
 from . import sale_order_line
 from . import stock_route
+from . import stock_picking

sale_stock_warehouse_multicompany/models/stock_picking.py

@@ -0,0 +1,16 @@
+# Copyright 2025 Jacques-Etienne Baudoux (BCIM) <je@bcim.be>
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+
+from odoo import models
+
+
+class StockPicking(models.Model):
+    _inherit = "stock.picking"
+
+    def _get_allowed_companies(self):
+        return self.company_id | self.sudo().move_ids.sale_line_id.company_id
+
+    def button_validate(self):
+        # Extend access to all related SO companies
+        self = self.with_context(allowed_company_ids=self._get_allowed_companies().ids)
+        return super().button_validate()