How do I update parcel tracking links and item identifier, like IMEI’s, on my processed orders via API?

As we enforce that the STATE is set to SHIPPED the best way to set a parcel tracking link and state in one call, using this route:

/refb.merchant.v1.OrderItemService/UpdateOrderItemState

with a request body like:

{
  "id": "1234567",
  "state": "SHIPPED",
  "parcel_tracking_url": "<https://dhl.com?foobar=1234>",
	"item_identifier": "IMANIMEINO000"
}

Be aware that you need to use the OrderItemID not the OrderID. So you probably want to call:

/refb.merchant.v1.OrderItemService/ListOrderItemsByOrder

with a request body like:

{
"order_id": "1234567"
}

before, to fetch the OrderItemID(s).