OpenAI Daybreak is frontier AI for cyber defenders and OpenAI’s vision for changing the way software is built and defended. Daybreak means seeing risk earlier, acting sooner, and helping make software resilient by design, starting from the premise that the next era of cyber defense should be built into software from the beginning. It is not only about finding and patching vulnerabilities, but about helping systems become resilient to them by design. Daybreak brings AI into modern cyber defense by helping defenders reason across codebases, identify subtle vulnerabilities, validate fixes, analyze unfamiliar systems, and move from discovery to remediation faster. Because those same capabilities can be misused, Daybreak pairs expanded defensive capability with trust, verification, proportional safeguards, and accountability. It combines the intelligence of OpenAI models, the extensibility of Codex as an agentic harness, and security partners across the security flywheel.