the ghost and pantheon entries keyed on each platform's older unclaimed-domain
copy, which the live pages no longer serve, so a real dangling subdomain went
undetected. verified against live unclaimed subdomains: <random>.ghost.io now
returns "Failed to resolve DNS path for this host" and <random>.pantheonsite.io
returns a "404 - Unknown site" page. key on those instead.
ghost also serves a bare "Site unavailable." on some hosts; the body match holds
one substring per service, so it keys on the distinctive arm and a page showing
only "Site unavailable." is not detected.
