Constant NO_HOST 

pub const NO_HOST: &str = "the scheduler-equivalence gate needs the Metrale Engine server that \
    serves the checkpoint: it re-serves the model under each router itself. Run it from the \
    dashboard's Benchmarks pane, or headless with `met bench run scheduler-equivalence \
    --pull-request-gate`, which starts the server in this process. Pointing it at a foreign \
    endpoint with --url cannot work: the endpoint would stay on one router.";

2026-09-26: What to tell the operator when nothing is installed.