use std::io;use futures::future::BoxFuture;use tokio::io::DuplexStream;/// Recreates a fresh in-process MCP byte stream whenever the client needs one.////// Implementations are expected to start the paired server side before/// returning the client stream. The factory is retained by [`crate::RmcpClient`]/// so reconnects can rebuild the transport without knowing which built-in/// server produced it.pub trait InProcessTransportFactory: Send + Sync {    fn open(&self) -> BoxFuture<'static, io::Result<DuplexStream>>;}