This skill should be used when the user says "batch simplify", "cross-feature simplify", "batch simplification", "simplify all features", "cross-feature quality pass", "batch code cleanup", "consolidate across features", "deduplicate across features", "cleanup after batch merge", "cross-feature deduplication", "arness batch simplify", "arn-code-batch-simplify", "simplify merged features", "post-merge simplify", "find cross-feature duplication", or wants to run a post-merge quality pass that finds duplication and consolidation opportunities across independently implemented features. This requires merged features in .arness/plans/ — run arn-code-batch-merge first if none are merged.