Function update_supernode 

async fn update_supernode(
    __arg0: State<Arc<SharedState>>,
    __arg1: Path<String>,
    __arg2: Json<SupernodeConfig>,
) -> impl IntoResponse

PUT /api/supernodes/{name} — upserts a definition from the JSON body (the path name overrides any name in the body), then revalidates and recompiles all route graphs — every policy using this supernode picks up the change atomically. Returns {"status": "updated"} on success.

Errors: 400 Bad Request if the definition is invalid or any consuming policy stops compiling (the previous compiled routes stay active).