feat(unseal): add unseal protocol and crypto infrastructure

server/crates/arbiter-proto/src/transport.rs

@@ -0,0 +1,46 @@
+use futures::{Stream, StreamExt};
+use tokio::sync::mpsc::{self, error::SendError};
+use tonic::{Status, Streaming};
+
+
+// Abstraction for stream for sans-io capabilities
+pub trait Bi<T, U>: Stream<Item = Result<T, Status>> + Send + Sync + 'static {
+    type Error;
+    fn send(
+        &mut self,
+        item: Result<U, Status>,
+    ) -> impl std::future::Future<Output = Result<(), Self::Error>> + Send;
+}
+
+// Bi-directional stream abstraction for handling gRPC streaming requests and responses
+pub struct BiStream<T, U> {
+    pub request_stream: Streaming<T>,
+    pub response_sender: mpsc::Sender<Result<U, Status>>,
+}
+
+impl<T, U> Stream for BiStream<T, U>
+where
+    T: Send + 'static,
+    U: Send + 'static,
+{
+    type Item = Result<T, Status>;
+
+    fn poll_next(
+        mut self: std::pin::Pin<&mut Self>,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Option<Self::Item>> {
+        self.request_stream.poll_next_unpin(cx)
+    }
+}
+
+impl<T, U> Bi<T, U> for BiStream<T, U>
+where
+    T: Send + 'static,
+    U: Send + 'static,
+{
+    type Error = SendError<Result<U, Status>>;
+
+    async fn send(&mut self, item: Result<U, Status>) -> Result<(), Self::Error> {
+        self.response_sender.send(item).await
+    }
+}