OpenAI has started rolling out the GPT-5.6 series models in limited preview to a small group of trusted partners through the API and Codex. The series includes Sol as the flagship model, Terra as a balanced option, and Luna as the fastest and most cost-efficient model. The rollout is being coordinated with the U.S. government before expanding to ChatGPT, Codex, and API users in the coming weeks. Key capabilities Sol introduces improved agentic capabilities for coding, biology, and cybersecurity. In coding, Sol tops the Terminal-Bench 2.1 benchmark. In cybersecurity, GPT-5.6 advances the performance-efficiency frontier on long-horizon security tasks, including vulnerability research and exploitation. OpenAI says it developed safeguards tailored to each model’s capabilities, with the goal of making prohibited offensive activity more difficult, uncertain, and detectable while preserving legitimate uses. Sol could not carry out a complete cyberattack on its own in OpenAI’s tests. GPT-5.6 uses multiple layers of safety, and responses are screened for potentially harmful content during generation. OpenAI conducted automated red teaming to find universal jailbreaks that work across many prompts and contexts.