Function ground_subgraph 

pub fn ground_subgraph(
    graph: &Graph,
    query: &str,
    limit: usize,
    depth: usize,
    width: usize,
) -> Subgraph

Ground, then expand along edges (bidirectional, depth/width-bounded BFS) to surface the connected evidence chain — the deterministic “associative reading” of AriGraph/SAGE. limit anchors, depth hops, width neighbours expanded per node per hop.