File::Basename::fileparse($path, $suffix_pattern) — every real call site in the legacy plugin corpus passes the same "match a trailing dot plus any run of non-dot characters" suffix pattern (i.e. "the last extension"), so the second argument is accepted but ignored rather than genuinely interpreting an arbitrary suffix pattern. Returns [name-without-extension, directory-with-trailing-slash, extension-with-leading-dot], matching Perl's own return order.