Joshua Sherwood, Ben Aybar, Benjamin Kaplan

Researchers benchmarked frontier coding agents on their ability to autonomously implement an AlphaZero-style machine learning pipeline for Connect Four, a task designed to measure early warning signals for recursive AI self-improvement. Claude Opus 4.7 substantially outperformed competitors, winning seven of eight trials against the Pascal Pons solver as first-mover, while other agents achieved at most two wins. The task moved from impossible for frontier agents in January 2026 to near-saturation within months, and the researchers released code, data, and prompts for reproduction.