Function worktree_writable_roots 

pub async fn worktree_writable_roots(
    cwd: &Path,
    home: &Path,
) -> Result<Vec<PathBuf>>

Resolve the additional write scope for a repository editing seat.

Resolve Git’s common directory from the actual seat checkout, never by assuming .git is a directory. Canonicalize directories before handing them to a sandbox (notably /tmp aliases on macOS). Failure is a startup error: do not start work with an unusable lock/question route.