rehydrate is a knowledge-based backup and restore plugin for Mac developers. Instead of copying every byte, it captures only what's truly local — dotfiles, SSH keys, gitignored .env files, sessions, locally-authored projects — and records the rest (apps, packages, git repos) as small inventory files that a future LLM replays on the target machine. The plugin ships two slash commands, /rehydrate:backup and /rehydrate:restore, plus snapshot diff and reachability-based garbage collection. Every backup is verified end-to-end via a sandboxed test restore.