Onboard a supplier in Shopify B2B as a Vendor-Managed Inventory partner by exposing purchase order receipt via the Admin API

Verified steps

1. Confirm the supplier has a Shopify Partner account or a third-party ERP/WMS integration; design an API integration where the supplier can call your Shopify Admin API (or a middleware) to notify of incoming inventory.
2. When a purchase order is fulfilled by the supplier, receive the shipment notification and create an Inventory Transfer or use the inventoryAdjustQuantities mutation to credit the received quantities at the correct Shopify location ID.
3. Use the inventoryAdjustQuantities GraphQL mutation with reason 'received' and a changes array of {inventoryItemId, locationId, delta} to add received stock to the specific warehouse location.
4. Optionally create a PurchaseOrder using Shopify's purchase orders feature (available in Shopify admin) — the draft PO can be transmitted to the supplier and the supplier's fulfillment creates the receipt that closes the PO line.
5. Reconcile received quantities against expected PO lines by querying the purchase order's lineItems and comparing receivedQuantity against orderedQuantity — surface discrepancies for warehouse team review.
6. Subscribe to the inventory_levels/update webhook to propagate quantity changes downstream (e.g., to sales channel integrations or replenishment algorithms) in real time.