Open Messaging API rejecting structured quick replies payload

Is the /api/v2/conversations/messaging/conversations/{id}/messages endpoint strictly requiring the action field for quick replies? I’m sending a valid Open Messaging payload with type: 'quick-reply' and a text object, but the server returns a 400 Bad Request with no useful error body. The TypeScript SDK types allow this structure, so I’m assuming the validation logic is stricter than the schema suggests. Here’s the payload I’m posting.