Inventory Module in Medusa Flows
In this guide, you'll learn how Medusa uses the Inventory Module in its commerce flows, including product variant creation, adding to cart, order placement, order fulfillment, and order return.
Product Variant Creation#
When a product variant is created and its manage_inventory property's value is true and the variant's inventory_items are set, the Medusa application creates an inventory item associated with that product variant.

Add to Cart#
When a product variant with manage_inventory set to true is added to the cart, the Medusa application checks whether there's sufficient stocked quantity. If not, an error is thrown and the product variant won't be added to the cart.

Order is Placed#
When an order is placed, the Medusa application creates a reservation item for each product variant with manage_inventory set to true.

Order Fulfillment#
When an item in an order is fulfilled and the associated variant has its manage_inventory property set to true, the Medusa application:
- Subtracts the
reserved_quantityfrom thestocked_quantityin the inventory level associated with the variant's inventory item. - Resets the
reserved_quantityto0. - Deletes the associated reservation item.

Order Return#
When an item in an order is returned and the associated variant has its manage_inventory property set to true, the Medusa application increments the stocked_quantity of the inventory item's level with the returned quantity.

Dismissed Returned Items#
If a returned item is considered damaged or is dismissed, its quantity doesn't increment the stocked_quantity of the inventory item's level.