Inventory is not subtracted on placed order with enabled Manage Inventory

[chemicalkosek]

Bug report

Describe the bug

When Manage Inventory is enabled, variant inventory is not subtracted when order is placed.
This was reported by user on Discord, I have tested and indeed the issue exists. I would consider this quite critical.
User also reported that returning an item does increase the inventory count.

System information

Medusa version (including plugins): 1.7.6 (happens on 1.7.5 too)
Node.js version: 18.14
Database: postgres

Expected behavior

Inventory is subtracted when order is placed.

[olivermrbl]

This is likely due to carts being completed without using the cart-completion strategy, which contains the inventory adjustment step. E.g. if the OrderService.createFromCart is used directly, you will need tax lines creation, payment authorization, and inventory adjustment as preliminary steps.

I realise, the Stripe webhook endpoint does not currently handle this, so this might be the culprit to your issue. I've added it to our backlog and we will investigate and come up with a solution asap :)

[olivermrbl]

@chemicalkosek Can I get you to confirm that this is only when orders are created through the Stripe webhook? We will solve the webhook issue in #3257, so I am closing this to avoid confusion around our inventory management functionality.

[chemicalkosek]

Confirmed :) I saw the PR using cart completion strategy for webhook. Should definitely fix this.