Function dynamic_edges 

pub fn dynamic_edges(
    index: &Index<'_>,
    nodes: &[Node],
    trait_impls: &[TraitImpl],
) -> Vec<Edge>

Dynamic-dispatch fan-out edges: for every impl block naming a trait the corpus defines, trait_method -> impl_method (Calls, Dynamic) for each method the impl defines under a same-named trait method. Conservative over-approximation — every impl is assumed reachable through the trait — which is exactly why the edges carry the distinct Dynamic evidence. Pairing rule: the impl block names the trait (same file/module, or a named import) and the method names match.