diff --git a/codex-rs/exec-server/README.md b/codex-rs/exec-server/README.md
index af21dc568a..23e9dacfbf 100644
--- a/codex-rs/exec-server/README.md
+++ b/codex-rs/exec-server/README.md
@@ -1,6 +1,6 @@
 # codex-exec-server
 
-`codex-exec-server` is a small standalone stdio JSON-RPC server for spawning
+`codex-exec-server` is a small standalone WebSocket JSON-RPC server for spawning
 and controlling subprocesses through `codex-utils-pty`.
 
 This PR intentionally lands only the standalone binary, client, wire protocol,
@@ -18,11 +18,7 @@ unified-exec in this PR; it is only the standalone transport layer.
 
 ## Transport
 
-The server speaks newline-delimited JSON-RPC 2.0 over stdio.
-
-- `stdin`: one JSON-RPC message per line
-- `stdout`: one JSON-RPC message per line
-- `stderr`: reserved for logs / process errors
+The server speaks JSON-RPC 2.0 over WebSockets.
 
 Like the app-server transport, messages on the wire omit the `"jsonrpc":"2.0"`
 field and use the shared `codex-app-server-protocol` envelope types.
@@ -249,7 +245,7 @@ The crate exports:
 - protocol structs such as `ExecParams`, `ExecResponse`,
   `WriteParams`, `TerminateParams`, `ExecOutputDeltaNotification`, and
   `ExecExitedNotification`
-- `run_main()` for embedding the stdio server in a binary
+- `run_main()` for embedding the WebSocket server in a binary
 
 ## Example session
 
diff --git a/codex-rs/exec-server/src/client.rs b/codex-rs/exec-server/src/client.rs
index 2f314f3db3..a7680e73e8 100644
--- a/codex-rs/exec-server/src/client.rs
+++ b/codex-rs/exec-server/src/client.rs
@@ -17,8 +17,6 @@ use codex_app_server_protocol::FsWriteFileParams;
 use codex_app_server_protocol::FsWriteFileResponse;
 use codex_app_server_protocol::JSONRPCNotification;
 use serde_json::Value;
-use tokio::io::AsyncRead;
-use tokio::io::AsyncWrite;
 use tokio::sync::broadcast;
 use tokio::sync::mpsc;
 use tokio::time::timeout;
@@ -203,22 +201,6 @@ impl ExecServerClient {
         Ok(client)
     }
 
-    pub async fn connect_stdio<R, W>(
-        stdin: W,
-        stdout: R,
-        options: ExecServerClientConnectOptions,
-    ) -> Result<Self, ExecServerError>
-    where
-        R: AsyncRead + Unpin + Send + 'static,
-        W: AsyncWrite + Unpin + Send + 'static,
-    {
-        Self::connect(
-            JsonRpcConnection::from_stdio(stdout, stdin, "exec-server stdio".to_string()),
-            options,
-        )
-        .await
-    }
-
     pub async fn connect_websocket(
         args: RemoteExecServerConnectArgs,
     ) -> Result<Self, ExecServerError> {
diff --git a/codex-rs/exec-server/src/connection.rs b/codex-rs/exec-server/src/connection.rs
index af03fc0686..c17803b33f 100644
--- a/codex-rs/exec-server/src/connection.rs
+++ b/codex-rs/exec-server/src/connection.rs
@@ -1,11 +1,15 @@
 use codex_app_server_protocol::JSONRPCMessage;
 use futures::SinkExt;
 use futures::StreamExt;
+#[cfg(test)]
 use tokio::io::AsyncBufReadExt;
 use tokio::io::AsyncRead;
 use tokio::io::AsyncWrite;
+#[cfg(test)]
 use tokio::io::AsyncWriteExt;
+#[cfg(test)]
 use tokio::io::BufReader;
+#[cfg(test)]
 use tokio::io::BufWriter;
 use tokio::sync::mpsc;
 use tokio_tungstenite::WebSocketStream;
@@ -27,6 +31,7 @@ pub(crate) struct JsonRpcConnection {
 }
 
 impl JsonRpcConnection {
+    #[cfg(test)]
     pub(crate) fn from_stdio<R, W>(reader: R, writer: W, connection_label: String) -> Self
     where
         R: AsyncRead + Unpin + Send + 'static,
@@ -256,6 +261,7 @@ async fn send_malformed_message(
         .await;
 }
 
+#[cfg(test)]
 async fn write_jsonrpc_line_message<W>(
     writer: &mut BufWriter<W>,
     message: &JSONRPCMessage,