Function serve_activated 

pub(crate) async fn serve_activated<S>(
    service: S,
    listener: ActivatedListener,
) -> Result<()>
where
    S: Service<Stream>,

Serve service on an already-obtained socket-activated connected listener.

Status is logged, never written to stdout: under socket activation (e.g. varlinkctl’s exec: transport) the parent may treat our stdout as part of the protocol handshake, and any stray bytes there reset the connection.

The server loop runs inside a [tokio::task::LocalSet] so request handlers can spawn_local !Send work (see pull_stream). Both serve paths wrap exactly one LocalSet.