Cursor Confirms Its New Composer 2 Model Is Built on Moonshot AI's Kimi

Cursor, the $29.3 billion AI coding company, launched its new Composer 2 model this week, promoting it as offering "frontier-level coding intelligence." What they did not mention: the model is built on top of Kimi 2.5, an open-source model from Chinese AI lab Moonshot AI. The omission was quickly spotted by an X user named Fynn, who found code identifying Kimi as the underlying model. The discovery raised eyebrows given Cursor's massive valuation and $2 billion+ annualized revenue. Cursor's VP of developer education Lee Robinson acknowledged the Kimi foundation but pushed back on the idea that Composer 2 is simply a rebrand. According to Robinson, only about a quarter of the compute spent on the final model came from the Kimi base. The rest is from Cursor's own training, resulting in benchmark performance that's "very different" from Kimi's. Moonshot AI confirmed the arrangement was part of an authorized commercial partnership through Fireworks AI, and expressed pride in seeing their model used as a foundation. The bigger question is why Cursor did not credit Kimi from the start. Building on a Chinese AI model carries extra baggage right now, with the US-China AI competition framed as an existential tech rivalry. Cursor co-founder Aman Sanger admitted it was "a miss" and promised to do better with future models. On the technical side, Composer 2 posts strong numbers: 61.3 on CursorBench, 61.7 on Terminal-Bench 2.0, and 73.7 on SWE-bench Multilingual. It is priced at $0.50/M input and $2.50/M output tokens, with a faster variant available at higher pricing.