Sale Stock Cancel Restriction

This module adds a safety rule to sales orders that are linked to stock transfers (pickings). When a user clicks the cancel action on a sales order, the module first looks at all the stock transfers connected to that order and checks whether any of them are already in the 'Done' state, meaning the goods were actually shipped or received.

If a completed transfer exists, the module forces the normal cancellation routine on that transfer so Odoo raises its usual error and the sales order cannot be cancelled. This closes a gap in standard Odoo, where completed transfers are filtered out of the cancellation process and the order could otherwise be cancelled even though the stock movement already happened.

• Applies to the sales order screen and its cancel button/action.
• Touches the sale.order model and its related stock transfers (picking_ids).
• No new fields, menus, reports or scheduled jobs are added.
• No configuration is required; the restriction is active as soon as the module is installed.

The result is that once a delivery is done, the related sales order stays protected from cancellation, helping keep sales and stock records consistent.