An Express health check page says the lesson-publishing API is unavailable. The Node.js /ready endpoint is failing while /live still answers, and the on-call view shows the last readiness transition; it does not merely say "CPU high." That evidence is enough to ask whether learners lost access, whether only new publishing failed, and which release was serving traffic. TL;DR: give an Express service three deliberately different endpoints: /live proves the process can answer, /ready say...