Function neighbors_sql 

pub fn neighbors_sql(
    edge_table: &str,
    seed_ids: &[String],
    realms: &[String],
    limit: usize,
) -> String

One-hop neighbour edges for a set of seed node ids (both directions), used to graph-expand a contextual subgraph. Returns edge rows; the orchestrator derives the far endpoint per seed and follows target_namespace for cross-graph (catalog resource / trace) links. Caller must pass ≥1 seed.