Cursor launched a new coding model called Composer 2, marketing it as offering frontier-level coding intelligence without disclosing its origins. An X user quickly identified that the model was built on top of Kimi k2.5, an open-source model from Chinese AI company Moonshot AI. Cursor's VP of developer education confirmed the base but noted that roughly three-quarters of the compute used in training was Cursor's own, resulting in benchmark performance distinct from Kimi's. Moonshot AI confirmed the use was part of an authorized commercial partnership via Fireworks AI. Cursor co-founder Aman Sanger admitted it was a mistake not to disclose the Kimi base in the original announcement. The omission is notable given the geopolitical sensitivity around U.S. companies building on Chinese AI models amid the ongoing U.S.-China AI competition.
