Track Lulu print-job and line-item status through the fulfillment lifecycle

Steps

1. Create a Print-Job via the print-jobs endpoint, which returns a print_job_id.
2. Poll the Print-Job status endpoint (or read the status object on the Print-Job resource) to see its current stage: CREATED, UNPAID, PAYMENT_IN_PROGRESS, PRODUCTION_DELAYED, PRODUCTION_READY, IN_PRODUCTION, SHIPPED, or DELIVERED.
3. Watch for the terminal error states REJECTED (invalid input/file) and CANCELED.
4. Once SHIPPED, read the line_item_statuses array in the status response — each entry has its own name, line_item_id, and a messages object with tracking_id, tracking_urls, and carrier_name.
5. Match line_item_id back to the line items you submitted when creating the Print-Job to update per-book shipment tracking in your system.