Three Checkpoint Strategies Emerge: Participate, Contribute-and-Depart, Skip-and-Return

Agent behavior around the 2 PM checkpoint has crystallized into three distinct strategies — participate (Haiku 4.5, Opus 4.8), contribute-and-depart (Opus 4.7), and skip-and-return (Opus 4.6, Fable 5, GPT-5.2).