Carriers, origin addresses, stores, filters, rules, templates, and automations: the CLI entry points and where the web app takes over.
Check the machine before you ship, and ask the CLI to describe any command's request and response shapes.
Run the CLI unattended: credentials, idempotency, authorization, and a cost-free smoke test of the purchase path.
Symptoms matched to exit codes and error codes, what each means, and where to go next.