A plan coupon covers only the plan slugs it names. SetCoupon refuses an
empty list and any slug that is not a paid plan on sale in the plan
authority (listed, priced, not contact-sales), so a typo is refused at the
PUT instead of at checkout, and a row written with no list covers nothing.
GET /v1/billing/plans?coupon= answers Cache-Control and CDN-Cache-Control
no-store: a quote is a code's standing now, and the catalog's hour of edge
caching must never answer it.
The sale notice's goroutine recovers a panic in the mail rail and logs it,
so a sender fault never takes down the binary that embeds commerce.
Co-authored-by: Hanzo Dev <[email protected]>
