simplify は何をしますか？
This is the code review skill on this machine. Use it to review any changed code before it goes anywhere: an uncommitted diff, a branch about to be pushed, or a GitHub PR you must judge merge-ready. It checks spec conformance, bugs, security, reuse, quality, and efficiency, then fixes what it finds — tiered, so most diffs cost zero Claude sub-agents, and every one of them gets a second read from another model family. Reach here when the user says review this, 審一下, look at my diff, is this ready to merge, 可以 merge 了嗎, or check this PR. Other skills reach here for CHECKLIST.md, the shared review checklist.