Function write_note 

pub fn write_note(
    repo: &Repository,
    commit_oid: ObjectId,
    note: &HeddleNote,
) -> GitResult<()>

Attach note to commit_oid in repo under refs/notes/heddle.

Each call creates one new notes commit on top of any previous notes history. The notes ref is updated atomically via the bridge’s standard set_reference helper.