use-reference-reposlisted

# Use reference repositories Use `.repos` for open-source source-code references. Do not use the old refs CLI or a `references` directory. Feel free to fetch reference code whenever it would improve the work. This is pre-authorized: do not ask the user before initializing an existing reference submodule or adding a useful open-source repository as a new submodule. ## Use an existing reference Check `.gitmodules`, then initialize only the repository needed: ```sh git submodule update --init .repos/<repository> ``` The pinned commit is usually the right starting point. If current upstream code matters, fetch it normally and inspect the remote branch: ```sh git -C .repos/<repository> fetch origin ``` ## Add a reference When a useful project is not listed, add its official upstream repository directly: ```sh git submodule add https://github.com/<owner>/<repository>.git .repos/<repository> ``` Adding the submodule and `.gitmodules` entry is an intended repository change. Keep reference names short and match the upstream repository name unless that would be ambiguous. ## Rules - Pull the references relevant to the task; do not initialize every submodule by default. - Treat reference repositories as upstream source to inspect. Do not edit their contents unless the user explicitly asks to modify or contribute to that project. - Prefer source inspection over guessing when behavior depends on an upstream implementation. - Report the upstream repository and commit used when