fix: route standalone protocol through client transports

crates/client/Cargo.toml

@@ -5,6 +5,7 @@ edition.workspace = true
 license.workspace = true
 
 [dependencies]
+async-trait.workspace = true
 chrono = { version = "0.4", default-features = false, features = ["clock"] }
 protocol = { workspace = true }
 ticket = { workspace = true }

crates/client/src/backend_runtime.rs

@@ -1,13 +1,7 @@
-use crate::{BackendApiClient, BackendApiClientError};
-use futures::{SinkExt, StreamExt};
-use protocol::stream::{decode_event, encode_method};
-use protocol::{ErrorCode, Event, Method};
+use crate::transport::websocket::{Socket as WebSocket, SocketError as WebSocketError};
+use crate::{BackendApiClient, BackendApiClientError, Client};
 use reqwest::Method as HttpMethod;
-use std::collections::VecDeque;
 use std::fmt;
-use tokio::sync::mpsc;
-use tokio_tungstenite::connect_async;
-use tokio_tungstenite::tungstenite::Message as TungsteniteMessage;
 use tokio_tungstenite::tungstenite::client::IntoClientRequest;
 use tokio_tungstenite::tungstenite::http::HeaderValue;
 use tokio_tungstenite::tungstenite::http::header::AUTHORIZATION;
@@ -106,20 +100,12 @@ impl BackendRuntimeListTarget {
     }
 }
 
-#[derive(Debug)]
-pub struct BackendRuntimeClient {
-    target: BackendRuntimeTarget,
-    command_tx: mpsc::UnboundedSender<Method>,
-    events: mpsc::UnboundedReceiver<Event>,
-    diagnostics: VecDeque<Event>,
-    _protocol_task: tokio::task::JoinHandle<()>,
-}
-
 #[derive(Debug)]
 pub enum BackendRuntimeClientError {
     InvalidTarget(String),
     Api(BackendApiClientError),
     Http(reqwest::Error),
+    Protocol(String),
 }
 
 impl fmt::Display for BackendRuntimeClientError {
@@ -128,6 +114,7 @@ impl fmt::Display for BackendRuntimeClientError {
             Self::InvalidTarget(message) => f.write_str(message),
             Self::Api(error) => write!(f, "{error}"),
             Self::Http(error) => write!(f, "{error}"),
+            Self::Protocol(message) => f.write_str(message),
         }
     }
 }
@@ -282,151 +269,22 @@ pub async fn restore_backend_worker(
     Ok(response.json::<BackendWorkerRestoreResponse>().await?)
 }
 
-impl BackendRuntimeClient {
-    pub async fn connect(target: BackendRuntimeTarget) -> Result<Self, BackendRuntimeClientError> {
-        validate_target(&target)?;
-        let api = BackendApiClient::from_stored_token(&target.base_url)?;
-        let (event_tx, rx) = mpsc::unbounded_channel();
-        let (command_tx, command_rx) = mpsc::unbounded_channel();
-
-        let protocol_target = target.clone();
-        let protocol_event_tx = event_tx.clone();
-        let protocol_task = tokio::spawn(async move {
-            run_worker_protocol_transport(protocol_target, api, command_rx, protocol_event_tx)
-                .await;
-        });
-
-        Ok(Self {
-            target,
-            command_tx,
-            events: rx,
-            diagnostics: VecDeque::new(),
-            _protocol_task: protocol_task,
-        })
-    }
-
-    pub fn try_next_event(&mut self) -> Option<Event> {
-        if let Some(event) = self.diagnostics.pop_front() {
-            return Some(event);
-        }
-        self.events.try_recv().ok()
-    }
-
-    pub async fn next_event(&mut self) -> Option<Event> {
-        if let Some(event) = self.diagnostics.pop_front() {
-            return Some(event);
-        }
-        self.events.recv().await
-    }
-
-    pub async fn send(&mut self, method: &Method) -> Result<(), BackendRuntimeClientError> {
-        self.command_tx.send(method.clone()).map_err(|_| {
-            BackendRuntimeClientError::InvalidTarget(format!(
-                "Backend protocol command stream is closed for {}",
-                self.target.display_label()
-            ))
-        })?;
-        Ok(())
-    }
-}
-
-impl Drop for BackendRuntimeClient {
-    fn drop(&mut self) {
-        self._protocol_task.abort();
-    }
-}
-
-async fn run_worker_protocol_transport(
+pub async fn connect_backend_runtime(
     target: BackendRuntimeTarget,
-    api: BackendApiClient,
-    mut commands: mpsc::UnboundedReceiver<Method>,
-    tx: mpsc::UnboundedSender<Event>,
-) {
-    let request = match protocol_ws_request(&target, &api) {
-        Ok(request) => request,
-        Err(error) => {
-            let _ = tx.send(diagnostic_event(format!(
-                "Backend protocol request could not be constructed for {}: {error}",
-                target.display_label()
-            )));
-            return;
-        }
-    };
-    match connect_async(request).await {
-        Ok((ws, _)) => {
-            let (mut sink, mut stream) = ws.split();
-            loop {
-                tokio::select! {
-                    maybe_method = commands.recv() => {
-                        let Some(method) = maybe_method else {
-                            break;
-                        };
-                        match encode_method(&method) {
-                            Ok(text) => {
-                                if let Err(error) = sink.send(TungsteniteMessage::Text(text.into())).await {
-                                    let _ = tx.send(diagnostic_event(format!(
-                                        "Backend protocol command send failed for {}: {error}",
-                                        target.display_label()
-                                    )));
-                                    break;
-                                }
-                            }
-                            Err(error) => {
-                                let _ = tx.send(diagnostic_event(format!(
-                                    "Backend protocol command could not serialize method for {}: {error}",
-                                    target.display_label()
-                                )));
-                            }
-                        }
-                    }
-                    frame = stream.next() => {
-                        match frame {
-                            Some(Ok(TungsteniteMessage::Text(text))) => {
-                                match decode_event(&text) {
-                                    Ok(event) => {
-                                        let _ = tx.send(event);
-                                    }
-                                    Err(error) => {
-                                        let _ = tx.send(diagnostic_event(format!(
-                                            "Backend protocol response was not valid Event JSON for {}: {error}",
-                                            target.display_label()
-                                        )));
-                                    }
-                                }
-                            }
-                            Some(Ok(TungsteniteMessage::Close(_))) | None => {
-                                let _ = tx.send(diagnostic_event(format!(
-                                    "Backend protocol command stream closed for {}",
-                                    target.display_label()
-                                )));
-                                break;
-                            }
-                            Some(Ok(TungsteniteMessage::Ping(_)))
-                            | Some(Ok(TungsteniteMessage::Pong(_)))
-                            | Some(Ok(TungsteniteMessage::Binary(_)))
-                            | Some(Ok(TungsteniteMessage::Frame(_))) => {}
-                            Some(Err(error)) => {
-                                let _ = tx.send(diagnostic_event(format!(
-                                    "Backend protocol WebSocket error for {}: {error}",
-                                    target.display_label()
-                                )));
-                                break;
-                            }
-                        }
-                    }
-                }
-            }
-        }
-        Err(error) => {
-            let message = protocol_connect_error_message(&target, &api, &error);
-            let _ = tx.send(diagnostic_event(message));
-            while commands.recv().await.is_some() {
-                let _ = tx.send(diagnostic_event(format!(
-                    "Backend protocol command was not sent because command stream is unavailable for {}",
-                    target.display_label()
-                )));
-            }
-        }
+) -> Result<Client<WebSocket>, BackendRuntimeClientError> {
+    validate_target(&target)?;
+    let api = BackendApiClient::from_stored_token(&target.base_url)?;
+    let request = protocol_ws_request(&target, &api).map_err(|error| {
+        BackendRuntimeClientError::Protocol(format!(
+            "Backend protocol request could not be constructed for {}: {error}",
+            target.display_label()
+        ))
+    })?;
+    match WebSocket::connect(request).await {
+        Ok(socket) => Ok(Client::new(socket)),
+        Err(WebSocketError::WebSocket(error)) => Err(BackendRuntimeClientError::Protocol(
+            protocol_connect_error_message(&target, &api, &error),
+        )),
     }
 }
 
@@ -453,13 +311,6 @@ fn protocol_connect_error_message(
     )
 }
 
-fn diagnostic_event(message: impl Into<String>) -> Event {
-    Event::Error {
-        code: ErrorCode::Internal,
-        message: message.into(),
-    }
-}
-
 fn validate_target(target: &BackendRuntimeTarget) -> Result<(), BackendRuntimeClientError> {
     if target.base_url.trim().is_empty() {
         return Err(BackendRuntimeClientError::InvalidTarget(

crates/client/src/client.rs

@@ -0,0 +1,137 @@
+use std::error::Error;
+use std::fmt;
+
+use protocol::stream::{decode_event, encode_method};
+use protocol::{Event, Method};
+
+use crate::transport::Socket;
+
+/// Typed Worker protocol client over an injected message transport.
+pub struct Client<T> {
+    socket: T,
+}
+
+#[derive(Debug)]
+pub enum ClientError<E> {
+    Transport(E),
+    Protocol(serde_json::Error),
+}
+
+impl<T> Client<T> {
+    pub fn new(socket: T) -> Self {
+        Self { socket }
+    }
+
+    pub fn into_inner(self) -> T {
+        self.socket
+    }
+}
+
+impl<T: Socket> Client<T> {
+    pub async fn send(&mut self, method: &Method) -> Result<(), ClientError<T::Error>> {
+        let message = encode_method(method).map_err(ClientError::Protocol)?;
+        self.socket
+            .send(message)
+            .await
+            .map_err(ClientError::Transport)
+    }
+
+    pub async fn next_event(&mut self) -> Result<Option<Event>, ClientError<T::Error>> {
+        self.socket
+            .next()
+            .await
+            .map_err(ClientError::Transport)?
+            .map(|message| decode_event(&message).map_err(ClientError::Protocol))
+            .transpose()
+    }
+
+    pub fn try_next_event(&mut self) -> Result<Option<Event>, ClientError<T::Error>> {
+        self.socket
+            .try_next()
+            .map_err(ClientError::Transport)?
+            .map(|message| decode_event(&message).map_err(ClientError::Protocol))
+            .transpose()
+    }
+}
+
+impl<E: fmt::Display> fmt::Display for ClientError<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Transport(error) => write!(formatter, "Worker transport error: {error}"),
+            Self::Protocol(error) => write!(formatter, "Worker protocol error: {error}"),
+        }
+    }
+}
+
+impl<E: Error + 'static> Error for ClientError<E> {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            Self::Transport(error) => Some(error),
+            Self::Protocol(error) => Some(error),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::VecDeque;
+    use std::convert::Infallible;
+
+    use async_trait::async_trait;
+    use protocol::stream::{decode_method, encode_event};
+    use protocol::{Event, Method, WorkerStatus};
+
+    use super::Client;
+    use crate::transport::Socket;
+
+    #[derive(Default)]
+    struct TestSocket {
+        sent: Vec<String>,
+        incoming: VecDeque<String>,
+    }
+
+    #[async_trait]
+    impl Socket for TestSocket {
+        type Error = Infallible;
+
+        async fn send(&mut self, message: String) -> Result<(), Self::Error> {
+            self.sent.push(message);
+            Ok(())
+        }
+
+        async fn next(&mut self) -> Result<Option<String>, Self::Error> {
+            Ok(self.incoming.pop_front())
+        }
+
+        fn try_next(&mut self) -> Result<Option<String>, Self::Error> {
+            Ok(self.incoming.pop_front())
+        }
+    }
+
+    #[tokio::test]
+    async fn encodes_methods_and_decodes_events_above_transport() {
+        let mut socket = TestSocket::default();
+        socket.incoming.push_back(
+            encode_event(&Event::Status {
+                status: WorkerStatus::Idle,
+            })
+            .expect("encode event"),
+        );
+        let mut client = Client::new(socket);
+
+        client
+            .send(&Method::run_text("hello"))
+            .await
+            .expect("send method");
+        assert!(matches!(
+            decode_method(&client.socket.sent[0]),
+            Ok(Method::Run { .. })
+        ));
+        assert!(matches!(
+            client.next_event().await,
+            Ok(Some(Event::Status {
+                status: WorkerStatus::Idle
+            }))
+        ));
+    }
+}

crates/client/src/lib.rs

@@ -7,8 +7,9 @@ pub mod backend_api;
 mod backend_auth;
 pub mod backend_runtime;
 pub mod backend_workspace;
+mod client;
 pub mod target;
-mod worker_client;
+pub mod transport;
 mod workspace_product;
 
 pub use backend_api::{
@@ -20,23 +21,23 @@ pub use backend_auth::{
     poll_device_login, start_device_login, wait_for_device_login,
 };
 pub use backend_runtime::{
-    BackendDiagnostic, BackendDiagnosticSeverity, BackendRuntimeClient, BackendRuntimeClientError,
+    BackendDiagnostic, BackendDiagnosticSeverity, BackendRuntimeClientError,
     BackendRuntimeListResponse, BackendRuntimeListTarget, BackendRuntimeSummary,
     BackendRuntimeTarget, BackendWorkerCapabilitySummary, BackendWorkerImplementationSummary,
     BackendWorkerRestoreResponse, BackendWorkerRestoreResult, BackendWorkerSummary,
-    BackendWorkerWorkspaceSummary, BackendWorkingDirectorySummary, list_backend_stopped_workers,
-    list_backend_workers, restore_backend_worker,
+    BackendWorkerWorkspaceSummary, BackendWorkingDirectorySummary, connect_backend_runtime,
+    list_backend_stopped_workers, list_backend_workers, restore_backend_worker,
 };
 pub use backend_workspace::{
     BackendWorkspace, BackendWorkspaceCatalogTarget, BackendWorkspaceClientError,
     CreateBackendWorkspaceRepository, CreateBackendWorkspaceRequest,
     CreateBackendWorkspaceResponse, create_backend_workspace, list_backend_workspaces,
 };
+pub use client::{Client, ClientError};
 pub use target::{
     BackendTarget, Dashboard, ResolvedTarget, StandaloneSessionListIntent,
     StandaloneSessionResumeIntent, StandaloneTarget, Target, TargetError, TargetKind,
     WorkerConnection, WorkerConnectionSelector, WorkerList, WorkerListRequest, WorkerSpawn,
 };
-pub use worker_client::WorkerClient;
 pub use workspace_api::{ObjectiveDetail, ObjectiveSummary};
 pub use workspace_product::BackendWorkspaceProductClient;

crates/client/src/transport/in_process.rs

@@ -0,0 +1,115 @@
+use async_trait::async_trait;
+use thiserror::Error;
+use tokio::sync::mpsc;
+
+use super::Socket as SocketContract;
+
+const CHANNEL_CAPACITY: usize = 256;
+
+pub struct Socket {
+    outgoing: mpsc::Sender<String>,
+    incoming: mpsc::Receiver<String>,
+}
+
+/// Host-side endpoint paired with an in-process client transport.
+pub struct Peer {
+    incoming: mpsc::Receiver<String>,
+    outgoing: mpsc::Sender<String>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+pub enum SocketError {
+    #[error("in-process Worker protocol transport closed")]
+    Closed,
+}
+
+impl Socket {
+    pub fn pair() -> (Self, Peer) {
+        let (client_tx, peer_rx) = mpsc::channel(CHANNEL_CAPACITY);
+        let (peer_tx, client_rx) = mpsc::channel(CHANNEL_CAPACITY);
+        (
+            Self {
+                outgoing: client_tx,
+                incoming: client_rx,
+            },
+            Peer {
+                incoming: peer_rx,
+                outgoing: peer_tx,
+            },
+        )
+    }
+}
+
+#[async_trait]
+impl SocketContract for Socket {
+    type Error = SocketError;
+
+    async fn send(&mut self, message: String) -> Result<(), Self::Error> {
+        self.outgoing
+            .send(message)
+            .await
+            .map_err(|_| SocketError::Closed)
+    }
+
+    async fn next(&mut self) -> Result<Option<String>, Self::Error> {
+        Ok(self.incoming.recv().await)
+    }
+
+    fn try_next(&mut self) -> Result<Option<String>, Self::Error> {
+        match self.incoming.try_recv() {
+            Ok(message) => Ok(Some(message)),
+            Err(mpsc::error::TryRecvError::Empty | mpsc::error::TryRecvError::Disconnected) => {
+                Ok(None)
+            }
+        }
+    }
+}
+
+impl Peer {
+    pub async fn next(&mut self) -> Option<String> {
+        self.incoming.recv().await
+    }
+
+    pub async fn send(&self, message: String) -> Result<(), String> {
+        self.outgoing.send(message).await.map_err(|error| error.0)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use protocol::stream::{decode_method, encode_event};
+    use protocol::{Event, Method, WorkerStatus};
+
+    use super::Socket;
+    use crate::Client;
+
+    #[tokio::test]
+    async fn pair_carries_typed_protocol_through_generic_client() {
+        let (socket, mut peer) = Socket::pair();
+        let mut client = Client::new(socket);
+
+        client
+            .send(&Method::run_text("hello"))
+            .await
+            .expect("send method");
+        assert!(matches!(
+            peer.next().await.as_deref().map(decode_method),
+            Some(Ok(Method::Run { .. }))
+        ));
+
+        peer.send(
+            encode_event(&Event::Status {
+                status: WorkerStatus::Idle,
+            })
+            .expect("encode event"),
+        )
+        .await
+        .expect("send event");
+        assert!(matches!(
+            client.next_event().await,
+            Ok(Some(Event::Status {
+                status: WorkerStatus::Idle
+            }))
+        ));
+    }
+}

crates/client/src/transport/mod.rs

@@ -0,0 +1,22 @@
+use std::error::Error;
+
+use async_trait::async_trait;
+
+pub mod in_process;
+pub mod unix_socket;
+pub mod websocket;
+
+/// Message-oriented transport for one Worker protocol connection.
+///
+/// Implementations own physical framing. `client::Client` owns the typed
+/// Method/Event protocol encoding layered on top of these UTF-8 messages.
+#[async_trait]
+pub trait Socket {
+    type Error: Error + Send + Sync + 'static;
+
+    async fn send(&mut self, message: String) -> Result<(), Self::Error>;
+
+    async fn next(&mut self) -> Result<Option<String>, Self::Error>;
+
+    fn try_next(&mut self) -> Result<Option<String>, Self::Error>;
+}

crates/client/src/transport/unix_socket.rs

@@ -0,0 +1,172 @@
+use std::io;
+use std::path::Path;
+
+use async_trait::async_trait;
+use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::net::UnixStream;
+use tokio::sync::mpsc;
+use tokio::task::JoinHandle;
+
+use super::Socket as SocketContract;
+
+pub struct Socket {
+    writer: tokio::io::WriteHalf<UnixStream>,
+    messages: mpsc::Receiver<io::Result<String>>,
+    reader_task: JoinHandle<()>,
+}
+
+impl Socket {
+    pub async fn connect(path: &Path) -> io::Result<Self> {
+        let stream = UnixStream::connect(path).await?;
+        let (reader, writer) = tokio::io::split(stream);
+        let (message_tx, messages) = mpsc::channel(256);
+        let reader_task = tokio::spawn(async move {
+            let mut lines = BufReader::new(reader).lines();
+            loop {
+                match lines.next_line().await {
+                    Ok(Some(message)) if message.trim().is_empty() => {}
+                    Ok(Some(message)) => {
+                        if message_tx.send(Ok(message)).await.is_err() {
+                            return;
+                        }
+                    }
+                    Ok(None) => return,
+                    Err(error) => {
+                        let _ = message_tx.send(Err(error)).await;
+                        return;
+                    }
+                }
+            }
+        });
+        Ok(Self {
+            writer,
+            messages,
+            reader_task,
+        })
+    }
+}
+
+#[async_trait]
+impl SocketContract for Socket {
+    type Error = io::Error;
+
+    async fn send(&mut self, message: String) -> Result<(), Self::Error> {
+        self.writer.write_all(message.as_bytes()).await?;
+        self.writer.write_all(b"\n").await?;
+        self.writer.flush().await
+    }
+
+    async fn next(&mut self) -> Result<Option<String>, Self::Error> {
+        match self.messages.recv().await {
+            Some(message) => message.map(Some),
+            None => Ok(None),
+        }
+    }
+
+    fn try_next(&mut self) -> Result<Option<String>, Self::Error> {
+        match self.messages.try_recv() {
+            Ok(message) => message.map(Some),
+            Err(mpsc::error::TryRecvError::Empty | mpsc::error::TryRecvError::Disconnected) => {
+                Ok(None)
+            }
+        }
+    }
+}
+
+impl Drop for Socket {
+    fn drop(&mut self) {
+        self.reader_task.abort();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::io::ErrorKind;
+    use std::time::Duration;
+
+    use protocol::stream::{decode_method, encode_event};
+    use protocol::{Event, Method, WorkerStatus};
+    use tempfile::tempdir;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::net::UnixListener;
+
+    use super::*;
+    use crate::Client;
+
+    async fn assert_peer_closed(stream: &mut UnixStream, reason: &str) {
+        let mut buf = [0_u8; 1];
+        match tokio::time::timeout(Duration::from_secs(1), stream.read(&mut buf))
+            .await
+            .expect(reason)
+        {
+            Ok(0) => {}
+            Err(error) if error.kind() == ErrorKind::ConnectionReset => {}
+            Ok(n) => panic!("server should observe peer close, read {n} byte(s)"),
+            Err(error) => panic!("server read failed unexpectedly: {error}"),
+        }
+    }
+
+    #[tokio::test]
+    async fn client_receives_events_over_unix_socket() {
+        let socket_dir = tempdir().unwrap();
+        let socket_path = socket_dir.path().join("events.sock");
+        let listener = UnixListener::bind(&socket_path).unwrap();
+        let server = tokio::spawn(async move {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            let event = encode_event(&Event::Status {
+                status: WorkerStatus::Idle,
+            })
+            .unwrap();
+            stream.write_all(event.as_bytes()).await.unwrap();
+            stream.write_all(b"\n").await.unwrap();
+        });
+
+        let mut client = Client::new(Socket::connect(&socket_path).await.unwrap());
+        let event = tokio::time::timeout(Duration::from_secs(1), client.next_event())
+            .await
+            .expect("client should receive event while alive")
+            .expect("transport should succeed");
+        assert!(matches!(
+            event,
+            Some(Event::Status {
+                status: WorkerStatus::Idle
+            })
+        ));
+        server.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn client_sends_methods_over_unix_socket() {
+        let socket_dir = tempdir().unwrap();
+        let socket_path = socket_dir.path().join("send.sock");
+        let listener = UnixListener::bind(&socket_path).unwrap();
+        let server = tokio::spawn(async move {
+            let (reader, _) = listener.accept().await.unwrap();
+            BufReader::new(reader).lines().next_line().await.unwrap()
+        });
+
+        let mut client = Client::new(Socket::connect(&socket_path).await.unwrap());
+        client
+            .send(&Method::run_text("hello"))
+            .await
+            .expect("send method");
+
+        let received = server.await.unwrap().expect("method message");
+        assert!(matches!(decode_method(&received), Ok(Method::Run { .. })));
+    }
+
+    #[tokio::test]
+    async fn dropping_socket_closes_server_connection() {
+        let socket_dir = tempdir().unwrap();
+        let socket_path = socket_dir.path().join("drop.sock");
+        let listener = UnixListener::bind(&socket_path).unwrap();
+        let server = tokio::spawn(async move {
+            let (mut stream, _) = listener.accept().await.unwrap();
+            assert_peer_closed(&mut stream, "dropped socket should close promptly").await;
+        });
+
+        let socket = Socket::connect(&socket_path).await.unwrap();
+        drop(socket);
+        server.await.unwrap();
+    }
+}

crates/client/src/transport/websocket.rs

@@ -0,0 +1,140 @@
+use async_trait::async_trait;
+use futures::{SinkExt, StreamExt};
+use thiserror::Error;
+use tokio::net::TcpStream;
+use tokio::sync::mpsc;
+use tokio::task::JoinHandle;
+use tokio_tungstenite::tungstenite::http::Request;
+use tokio_tungstenite::tungstenite::{self, Message};
+use tokio_tungstenite::{MaybeTlsStream, WebSocketStream, connect_async};
+
+use super::Socket as SocketContract;
+
+type Writer = futures::stream::SplitSink<WebSocketStream<MaybeTlsStream<TcpStream>>, Message>;
+
+pub struct Socket {
+    writer: Writer,
+    messages: mpsc::Receiver<Result<String, SocketError>>,
+    reader_task: JoinHandle<()>,
+}
+
+#[derive(Debug, Error)]
+pub enum SocketError {
+    #[error("WebSocket transport failed: {0}")]
+    WebSocket(#[from] tungstenite::Error),
+}
+
+impl Socket {
+    pub async fn connect(request: Request<()>) -> Result<Self, SocketError> {
+        let (stream, _) = connect_async(request).await?;
+        let (writer, mut reader) = stream.split();
+        let (message_tx, messages) = mpsc::channel(256);
+        let reader_task = tokio::spawn(async move {
+            loop {
+                match reader.next().await {
+                    Some(Ok(Message::Text(message))) => {
+                        if message_tx.send(Ok(message.to_string())).await.is_err() {
+                            return;
+                        }
+                    }
+                    Some(Ok(Message::Close(_))) | None => return,
+                    Some(Ok(
+                        Message::Binary(_)
+                        | Message::Ping(_)
+                        | Message::Pong(_)
+                        | Message::Frame(_),
+                    )) => {}
+                    Some(Err(error)) => {
+                        let _ = message_tx.send(Err(SocketError::WebSocket(error))).await;
+                        return;
+                    }
+                }
+            }
+        });
+        Ok(Self {
+            writer,
+            messages,
+            reader_task,
+        })
+    }
+}
+
+#[async_trait]
+impl SocketContract for Socket {
+    type Error = SocketError;
+
+    async fn send(&mut self, message: String) -> Result<(), Self::Error> {
+        self.writer.send(Message::Text(message.into())).await?;
+        Ok(())
+    }
+
+    async fn next(&mut self) -> Result<Option<String>, Self::Error> {
+        match self.messages.recv().await {
+            Some(message) => message.map(Some),
+            None => Ok(None),
+        }
+    }
+
+    fn try_next(&mut self) -> Result<Option<String>, Self::Error> {
+        match self.messages.try_recv() {
+            Ok(message) => message.map(Some),
+            Err(mpsc::error::TryRecvError::Empty | mpsc::error::TryRecvError::Disconnected) => {
+                Ok(None)
+            }
+        }
+    }
+}
+
+impl Drop for Socket {
+    fn drop(&mut self) {
+        self.reader_task.abort();
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use futures::{SinkExt, StreamExt};
+    use protocol::stream::{decode_method, encode_event};
+    use protocol::{Event, Method, WorkerStatus};
+    use tokio::net::TcpListener;
+    use tokio_tungstenite::accept_async;
+    use tokio_tungstenite::tungstenite::client::IntoClientRequest;
+
+    use super::*;
+    use crate::Client;
+
+    #[tokio::test]
+    async fn carries_typed_protocol_through_generic_client() {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let address = listener.local_addr().unwrap();
+        let server = tokio::spawn(async move {
+            let (stream, _) = listener.accept().await.unwrap();
+            let mut socket = accept_async(stream).await.unwrap();
+            let message = socket.next().await.unwrap().unwrap();
+            assert!(matches!(
+                message,
+                Message::Text(ref text)
+                    if matches!(decode_method(text), Ok(Method::Run { .. }))
+            ));
+            let event = encode_event(&Event::Status {
+                status: WorkerStatus::Idle,
+            })
+            .unwrap();
+            socket.send(Message::Text(event.into())).await.unwrap();
+        });
+
+        let request = format!("ws://{address}").into_client_request().unwrap();
+        let mut client = Client::new(Socket::connect(request).await.unwrap());
+        client
+            .send(&Method::run_text("hello"))
+            .await
+            .expect("send method");
+        assert!(matches!(
+            client.next_event().await,
+            Ok(Some(Event::Status {
+                status: WorkerStatus::Idle
+            }))
+        ));
+        server.await.unwrap();
+    }
+}

crates/client/src/worker_client.rs

@@ -1,186 +0,0 @@
-use std::io;
-use std::path::Path;
-
-use protocol::stream::{JsonLineReader, JsonLineWriter};
-use protocol::{Event, Method};
-use tokio::net::UnixStream;
-use tokio::sync::mpsc;
-use tokio::task::JoinHandle;
-
-pub struct WorkerClient {
-    writer: JsonLineWriter<tokio::io::WriteHalf<UnixStream>>,
-    event_rx: mpsc::Receiver<Event>,
-    reader_task: JoinHandle<()>,
-}
-
-impl WorkerClient {
-    pub async fn connect(path: &Path) -> Result<Self, io::Error> {
-        let stream = UnixStream::connect(path).await?;
-        let (reader, writer) = tokio::io::split(stream);
-        let writer = JsonLineWriter::new(writer);
-
-        let (event_tx, event_rx) = mpsc::channel::<Event>(256);
-
-        let reader_task = tokio::spawn(async move {
-            let mut reader = JsonLineReader::new(reader);
-            while let Ok(Some(event)) = reader.next::<Event>().await {
-                if event_tx.send(event).await.is_err() {
-                    break;
-                }
-            }
-        });
-
-        Ok(Self {
-            writer,
-            event_rx,
-            reader_task,
-        })
-    }
-
-    pub async fn send(&mut self, method: &Method) -> Result<(), io::Error> {
-        self.writer.write(method).await
-    }
-
-    pub fn try_next_event(&mut self) -> Option<Event> {
-        self.event_rx.try_recv().ok()
-    }
-
-    pub async fn next_event(&mut self) -> Option<Event> {
-        self.event_rx.recv().await
-    }
-}
-
-impl Drop for WorkerClient {
-    fn drop(&mut self) {
-        self.reader_task.abort();
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use std::io::ErrorKind;
-    use std::time::Duration;
-
-    use protocol::{Segment, WorkerStatus};
-    use tempfile::tempdir;
-    use tokio::io::{AsyncReadExt, AsyncWriteExt};
-    use tokio::net::UnixListener;
-
-    use super::*;
-
-    async fn assert_peer_closed(stream: &mut UnixStream, reason: &str) {
-        let mut buf = [0_u8; 1];
-        match tokio::time::timeout(Duration::from_secs(1), stream.read(&mut buf))
-            .await
-            .expect(reason)
-        {
-            Ok(0) => {}
-            Err(error) if error.kind() == ErrorKind::ConnectionReset => {}
-            Ok(n) => panic!("server should observe peer close, read {n} byte(s)"),
-            Err(error) => panic!("server read failed unexpectedly: {error}"),
-        }
-    }
-
-    #[tokio::test]
-    async fn receives_events_while_client_is_alive() {
-        let socket_dir = tempdir().unwrap();
-        let socket_path = socket_dir.path().join("events.sock");
-        let listener = UnixListener::bind(&socket_path).unwrap();
-        let server = tokio::spawn(async move {
-            let (stream, _) = listener.accept().await.unwrap();
-            let mut writer = JsonLineWriter::new(stream);
-            writer
-                .write(&Event::Status {
-                    status: WorkerStatus::Idle,
-                })
-                .await
-                .unwrap();
-        });
-
-        let mut client = WorkerClient::connect(&socket_path).await.unwrap();
-
-        let event = tokio::time::timeout(Duration::from_secs(1), client.next_event())
-            .await
-            .expect("client should receive event while alive");
-        assert!(matches!(
-            event,
-            Some(Event::Status {
-                status: WorkerStatus::Idle
-            })
-        ));
-        server.await.unwrap();
-    }
-
-    #[tokio::test]
-    async fn send_writes_methods_while_client_is_alive() {
-        let socket_dir = tempdir().unwrap();
-        let socket_path = socket_dir.path().join("send.sock");
-        let listener = UnixListener::bind(&socket_path).unwrap();
-        let server = tokio::spawn(async move {
-            let (stream, _) = listener.accept().await.unwrap();
-            let mut reader = JsonLineReader::new(stream);
-            reader.next::<Method>().await.unwrap()
-        });
-
-        let mut client = WorkerClient::connect(&socket_path).await.unwrap();
-        let method = Method::Run {
-            input: vec![Segment::text("hello")],
-        };
-        client.send(&method).await.unwrap();
-
-        let received = tokio::time::timeout(Duration::from_secs(1), server)
-            .await
-            .expect("server should receive method while client is alive")
-            .unwrap();
-        match received {
-            Some(Method::Run { input }) => assert_eq!(input, vec![Segment::text("hello")]),
-            other => panic!("expected Run method, got {other:?}"),
-        }
-    }
-
-    #[tokio::test]
-    async fn dropping_repeated_clients_closes_server_connections() {
-        let socket_dir = tempdir().unwrap();
-        let socket_path = socket_dir.path().join("drop.sock");
-        let listener = UnixListener::bind(&socket_path).unwrap();
-        let server = tokio::spawn(async move {
-            for _ in 0..16 {
-                let (mut stream, _) = listener.accept().await.unwrap();
-                assert_peer_closed(
-                    &mut stream,
-                    "dropped client should close its socket promptly",
-                )
-                .await;
-            }
-        });
-
-        for _ in 0..16 {
-            let client = WorkerClient::connect(&socket_path).await.unwrap();
-            drop(client);
-        }
-
-        server.await.unwrap();
-    }
-
-    #[tokio::test]
-    async fn dropping_client_aborts_blocked_reader_task() {
-        let socket_dir = tempdir().unwrap();
-        let socket_path = socket_dir.path().join("blocked-reader.sock");
-        let listener = UnixListener::bind(&socket_path).unwrap();
-        let server = tokio::spawn(async move {
-            let (mut stream, _) = listener.accept().await.unwrap();
-            stream.write_all(b"{\"event\"").await.unwrap();
-            assert_peer_closed(
-                &mut stream,
-                "aborting the blocked client reader should close the socket",
-            )
-            .await;
-        });
-
-        let client = WorkerClient::connect(&socket_path).await.unwrap();
-        tokio::task::yield_now().await;
-        drop(client);
-
-        server.await.unwrap();
-    }
-}