[youtube:tab] in stderr fires for all YTM search page processing, not just artist channel expansion, causing channelExpanded=true for every search and returning [] — bypassing all YTM cascade steps entirely. Fix: only check stdout for /browse/UC (actual channel URL in results). Remove ytmsearch5: scheme which is not supported by this yt-dlp version. Revert pool to 10. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>