Google announced Gemini 4 Argon on September 28, 2026, its first new frontier model in more than six months, initially limited to trusted cyber defenders and enterprise cloud customers pending government safety evaluations, citing a 68% CWE Bench score. Bloomberg then reported insiders say it struggles with day-to-day tasks, and the restricted rollout drew a negative stock reaction. Google said it would be inaccurate to call Gemini 4 underperforming in coding, and Artificial Analysis puts Argon High's hallucination rate at 15% versus Astra's 51%. Argon agents migrated more than 800,000 lines in the Fuchsia OS Zircon kernel, and the model is now rolling out to the Gemini app and AI mode in search for Google AI Pro subscribers.