I really don't know what is it, but Claude Code just seems like an extremely well tuned package. You can have the same core models, but the internal prompts matter, how they are looking up extra context matters, how easy is it to add external context matters, how it applies changes matters, how eager is it to actually use an external tool to help you matters. With Claude Code, it just feels right. When I say I want a review, I get a review, when I want code, I get code, when I want just some git housekeeping, I get that.