Git repository identity

The hostlib tools.git_repository_identity method takes repo, a directory inside a working tree. It returns worktree_root and common_directory as absolute paths. Linked worktrees have different working-tree roots and the same common directory. Unrelated repositories have different common directories.

The operation invokes system Git with fixed arguments, without a shell or caller-supplied command. A missing Git executable, a non-repository directory, a bare repository, or an incomplete response returns an error. Consumers must keep a failed observation distinct from a selected project root. This read does not grant permission to execute a verifier or modify the repository.