Use when an existing or legacy codebase needs to enter the agentic-engineering workflow but has no chain documents (or only scattered legacy docs — README, wiki, design notes). Triggers on "onboard this repo", "migrate this project to agentic-engineering", "reverse-engineer the docs", "adopt this workflow on an existing codebase", "we already have a codebase, set up the docs", "document what we already built", or pointing the suite at a brownfield project. Reverse-engineers the code into an as-built documentation chain; changes docs, never code.
