Grok 4.5 Is the First Frontier Model Co-Trained With Cursor

xAI·high signal

xAI launched Grok 4.5 on July 8, describing it as Opus-class but faster and more token-efficient, at $2 per 1M input and $6 per 1M output. It was trained across tens of thousands of NVIDIA GB300 GPUs with RL over hundreds of thousands of tasks centered on multi-step software engineering, and — notably — trained alongside Cursor, shipping day-one in Cursor on all plans. A model lab co-developing with a coding-agent product rather than shipping to it is a new distribution pattern worth watching; Anthropic and OpenAI both ship into third-party IDEs but neither has claimed joint training.