AmpersandHQ/magento2-disable-stock-reservation

This module disables the inventory reservation logic introduced as part of MSI in Magento 2.3.3 - see
https://github.com/magento/inventory/issues/2269 for more information about the way MSI was implemented, and the issues
that can happen with external WMS integrations.

The Problem

During the order placement and fulfilment processes, Magento's MSI implementation will not decrement stock on order
placement - it will only do so on order shipment and refund.

Our Approach

This module will:

• Prevent all writes to the inventory_reservation table. It does so by using an around plugin on PlaceReservationsForSalesEventInterface
• Trigger stock deductions on order placement. See inventory_sales_source_deduction_processor plugin on Magento\Sales\Model\Service\OrderService.
• Prevent stock deductions on order shipment. See disabled inventory_sales_source_deduction_processor observer on sales_order_shipment_save_after event.
• Replenish stock for cancelled order items. See inventory observer on sales_order_item_cancel event.
• Replenish stock when a credit memo is issued. See src/Observer/RestoreSourceItemQuantityOnRefundObserver.php
  • Requires that "Back to stock" is checked or "Automatically Return Credit Memo Item to Stock" is configured
    • https://docs.magento.com/user-guide/configuration/catalog/inventory.html#product-stock-options
• Truncate (ie, remove all historic entries from) the inventory_reservation table upon installation.

Additional Notes

• Both the inventory and cataloginventory_stock should be on the same mode (Update on Save or Schedule) for this module to work as expected. If you are running this on Schedule you should have crons activated.