We measured the impact of AI on 46 OSS repos (200k commits, 16M lines)

Kerno's first-edition report analyzes 201,576 commits across 46 open-source projects from October 2024 to October 2026 and finds new code carries 8.1 decision points per 100 lines after AI adoption, up from 5.2, with complexity growth shifting from −0.4% to +3.1% a month. Each engineer ships 71% more production code per week, while AI-marked commits are revisited 43% more often than other commits and are 17% more likely to add a hard-to-test function. Claude signs 69% of AI-marked commits, which are 54% bigger than unmarked commits, and on the current trend complexity per 100 new lines would rise another 42% by late 2028.