What problem does it solve? Keeping a project's AI agent harness (agents, skills, hooks, settings) in sync with an upstream kit repository is error-prone: manual copying risks overwriting user customizations, missing stale files, or losing legacy content. This Skill automates the update with a safe dry-run, explicit confirmation, backups, and migration of legacy layouts. ## Core Features & Use Cases - Dry-run diff before applying: Clones the remote kit, resolves its manifest, computes add/modify/delete/preserve sets via compute-sync-plan.mjs, and prints a summary that requires explicit user confirmation before any change. - Safe apply with backups and snapshotting: Backs up modified and deleted files to .vibecode-backup/ (with rotation), applies the plan mechanically, fixes symlinks, writes .vc-installed-files and .vc-version, and guards .gitignore. - Legacy layout migration: Detects old-layout process/ artifacts (flat plan files, sibling reports//references/ dirs), migrates safe cases into task folders, and logs orphaned dirs for manual review. - Use Case: After a new harness release is announced, run the update to see exactly which of the 90+ managed files will change, preserve your merge-protected .claude/settings.json, and apply the upgrade with a recoverable backup. ## Quick Start Ask the agent to check for and apply the latest harness updates from the kit repository, reviewing the dry-run diff before confirming.