CHW-4404 BillingBodyInvalid

billing request body was missing or malformed; see /api/billing documentation for the expected shape

Default message: billing request body was missing or malformed; see /api/billing documentation for the expected shape
HTTP status: 400 (client)

Problem. /api/billing/checkout or /api/billy/chat returned 400 before any plan logic. Cause. The request body was missing, empty, or malformed JSON. Fix. Re-send with a valid JSON body matching the endpoint schema. HTTP 400.