On March 20, the AI programming tool Cursor unveiled its latest-generation programming model, Composer 2. The company boasted that through ongoing pre-training and self-improvement via reinforcement learning, Composer 2 had achieved outstanding results across multiple benchmark tests. However, soon after its release, developers uncovered that Composer 2 was actually built upon the foundation of Moonshot AI's Kimi K2.5 model. The initial omission of information regarding the base model raised eyebrows and fueled skepticism. Subsequently, Cursor's co-founder acknowledged that Composer 2 was indeed based on Kimi K2.5 and issued an apology, explaining that the failure to disclose the source of the base model was an unintentional oversight. Moonshot AI officially clarified that Cursor had secured commercial authorization for Kimi K2.5 through a third-party platform, and that the collaboration between the two entities fully complied with regulations. Elon Musk also publicly verified this information.