Use environment: "sandbox" with a br_test_ key. Staging and development
deployments reject production API keys and production WHCC credentials.
Sandbox compatibility and quotes are safe ways to test canonical validation,
provider availability, quote freezing, and idempotency. A provider must be
explicitly enabled with sandbox credentials and fulfillment switches before a
hosted order can reach a provider. Automated tests use mock transports only.
Richmond Pro Lab (rpl) is currently preview-only: it may appear in a
compatibility report but is unavailable for hosted sandbox or production orders
until credentials and provider verification are complete.
