Composer 2 is Cursor's declaration of independence from third-party models. By shipping a proprietary model trained specifically for its editor workflow, Cursor can optimize coding-specific behaviours - file awareness, multi-turn refactoring, framework-native suggestions - in ways that generic models can't match.
The model is based on Moonshot AI's Kimi 2.5 foundation, which reached near-parity with Claude Opus and GPT-5 on code benchmarks earlier this year. Bloomberg reported Cursor had been developing this capability since Q4 2025, with Composer 2 positioned as the first public release of the in-house stack.
AI coding tools are diverging into proprietary-model territory. Picking a tool now means picking a model philosophy as much as an editor - Cursor bets on its own stack, Claude Code bets on Anthropic.
