- GET /ready: ready -> 200 + diagnostic report (unchanged success body);
not ready -> 503 + {"error":"service_unavailable","request_id":id}
+ Retry-After: 30, consistent with the other public entry points
- drop the legacy {"status":"not_ready"} diagnostic block from the 503 body
(backward compatibility not required)
- HTTP 200/503 semantics preserved, so Uptime Kuma HTTP(s) monitors
(status-code based) keep working
- sync docs: README.md, README.zh-CN.md, docs/design.md, docs/deployment.md,
AGENTS.md, docs/todo.md