Function open_ws_message_stream 

pub async fn open_ws_message_stream(
    ctx: &Context,
    subject: Option<&str>,
    since: Option<u64>,
) -> Result<Stream>

Open an ephemeral pull-consumer message stream for the WebSocket bridge. Distinct from replay_projection’s consumer because the WS path needs a long-lived messages() stream (waits for new publishes) rather than a fetch-and-terminate loop.