The Sirius.X site lives at /sirius-x/ (and, via BCNR, at sirius.x on
Sia). /sirius/ was the pre-Sirius.X page — it stayed live and
divergent from the new site. Users bookmarking /sirius/ (or landing
via an old link) were seeing the old page and reasonably assuming
nothing worked, because none of the new dropdown / register modal /
inline search is on it.
Both /sirius/index.html and /sirius/register.html are now client-side
redirects to /sirius-x/. register.html preserves ?q= and lands on
/sirius-x/#search-input so old label-in-URL bookmarks still open the
merged landing search at the right spot. Meta-refresh fallback
handles JS-off. rel=canonical points at /sirius-x/.