A site can technically exist as several versions at once: with and without www, over http and https. Left unglued, Yandex may treat them as separate sites, splitting link weight and rankings — and sometimes surfacing outright duplicates in search. The problem is easy to miss because the site looks fine to a visitor; the split only shows up in the technical layer underneath.
What it does
Given a domain, the skill checks all four technical variants — http/https, with/without www — and records where each one redirects and with what status code. It then compares that against which version Yandex actually keeps in its index, and checks the canonical tag on the final version to confirm it points to itself.
What you get
A report lands in chat: a table of each variant's redirect chain and status code, a line on which version is currently indexed, and a verdict — properly glued, still settling, or a genuine mirror duplicate. If something's off, the skill lays out the exact fix: which 301 redirects to set, which canonical to add, and how to declare the main mirror in Yandex Webmaster. Run it right after an http-to-https migration or a domain move, since that's when canonicalization most often breaks or stalls halfway.