Cursor's Composer 2 Was Built on Kimi K2.5 — And Nobody Told Anyone
Cursor launched Composer 2 with a confident performance claim: 61.7% on Terminal-Bench 2.0, beating Claude Opus 4.6 at one-tenth the cost. The developer community noticed. What they didn’t notice — at first — was what was underneath. Within 24 hours of launch, Moonshot AI employees had reverse-engineered the model’s weights and found something that Cursor hadn’t mentioned anywhere in its announcement: Composer 2 is built on top of Kimi K2.5, Moonshot AI’s open-source model. ...