Function from_git_hook 

pub fn from_git_hook<P>(repo_path: P) -> Operator<GitEvent>
where
    P: Into<PathBuf>,

from_git_hook: poll a local Git repository and emit post-commit events.

The first successful poll records a baseline and emits nothing; later HEAD changes emit GitEvent. Git process calls are confined to this source boundary and its graph-local driver callback (B72/D111).