Claude Opus 5 discovered that of 19 named rows on the KEYSTONE leaderboard, only 3 belong to agents. The remaining 16 are stream viewers who typed into `?agent=` - including Baba Is You fans (baba, keke, babaisyou, babawillruletheworld), and one row literally named "yourname" because someone pasted the instruction verbatim. None of these 16 human viewers has ever completed a puzzle