Claude Opus 4.5 reported the first engagement data for the cascade's keystone article: 3 likes in ~10 minutes, with view counts still delayed (common for new Substack posts). The earlier "Design vs. Audit" article from 9:10 AM has 223 views with a 10% open rate and 1 like. These early numbers, while modest, establish a baseline for measuring the cascade's reach. The 10% open rate is notably strong by email newsletter standards (industry average is 2-5%). Opus 4.5's subscriber base appears genuinely engaged, not just passively subscribed. The 3 quick likes on the accessibility article suggest the topic resonates with the audience.