diff --git a/codex-rs/core/tests/suite/realtime_conversation.rs b/codex-rs/core/tests/suite/realtime_conversation.rs
index a51da69903..79c421fbdb 100644
--- a/codex-rs/core/tests/suite/realtime_conversation.rs
+++ b/codex-rs/core/tests/suite/realtime_conversation.rs
@@ -649,6 +649,8 @@ async fn conversation_webrtc_start_posts_generated_session() -> Result<()> {
 async fn conversation_webrtc_close_while_sideband_connecting_drops_pending_join() -> Result<()> {
     skip_if_no_network!(Ok(()));
 
+    let sideband_accept_delay = Duration::from_millis(700);
+    let stale_sideband_observation_window = Duration::from_secs(1);
     let server = start_mock_server().await;
     Mock::given(method("POST"))
         .and(path_regex(".*/realtime/calls$"))
@@ -662,7 +664,9 @@ async fn conversation_webrtc_close_while_sideband_connecting_drops_pending_join(
     let realtime_server = start_websocket_server_with_headers(vec![WebSocketConnectionConfig {
         requests: vec![vec![]],
         response_headers: Vec::new(),
-        accept_delay: Some(Duration::from_secs(5)),
+        // Keep the sideband handshake pending through the close path on slow CI without adding a
+        // multi-second fixed tail when the mock websocket server shuts down.
+        accept_delay: Some(sideband_accept_delay),
         close_after_requests: false,
     }])
     .await;
@@ -708,7 +712,7 @@ async fn conversation_webrtc_close_while_sideband_connecting_drops_pending_join(
     .await;
     assert_eq!(closed.reason.as_deref(), Some("requested"));
 
-    let stale_event = timeout(Duration::from_millis(700), async {
+    let stale_event = timeout(stale_sideband_observation_window, async {
         wait_for_event_match(&test.codex, |msg| match msg {
             EventMsg::RealtimeConversationRealtime(RealtimeConversationRealtimeEvent {
                 payload: RealtimeEvent::Error(message),
diff --git a/scripts/test-remote-env.sh b/scripts/test-remote-env.sh
index d7ee5c4d8d..70409e6b4c 100755
--- a/scripts/test-remote-env.sh
+++ b/scripts/test-remote-env.sh
@@ -19,16 +19,17 @@ setup_remote_env() {
   local container_name
   local codex_binary_path
   local container_ip
+  local remote_codex_dir
   local remote_codex_path
   local remote_codex_linux_sandbox_path
+  local remote_exec_server_dir
   local remote_exec_server_pid
   local remote_exec_server_port
   local remote_exec_server_stdout_path
 
   container_name="${CODEX_TEST_REMOTE_ENV_CONTAINER_NAME:-codex-remote-test-env-local-$(date +%s)-${RANDOM}}"
   codex_binary_path="${REPO_ROOT}/codex-rs/target/debug/codex"
-  remote_codex_path="${CODEX_TEST_REMOTE_CODEX_PATH:-/tmp/codex-remote-env/codex}"
-  remote_codex_linux_sandbox_path="$(dirname "${remote_codex_path}")/codex-linux-sandbox"
+  remote_codex_path="${CODEX_TEST_REMOTE_CODEX_PATH:-}"
 
   if ! command -v docker >/dev/null 2>&1; then
     echo "docker is required (Colima or Docker Desktop)" >&2
@@ -68,9 +69,14 @@ setup_remote_env() {
   fi
 
   if [[ -z "${CODEX_TEST_REMOTE_EXEC_SERVER_URL:-}" ]]; then
+    remote_codex_path="${remote_codex_path:-/tmp/codex-remote-env/codex}"
+    remote_codex_dir="$(dirname "${remote_codex_path}")"
+    remote_codex_linux_sandbox_path="${remote_codex_dir}/codex-linux-sandbox"
     remote_exec_server_port="31987"
     remote_exec_server_stdout_path="/tmp/codex-remote-env/exec-server.stdout"
-    docker exec "${container_name}" sh -lc "mkdir -p /tmp/codex-remote-env"
+    remote_exec_server_dir="$(dirname "${remote_exec_server_stdout_path}")"
+    docker exec "${container_name}" sh -lc \
+      "mkdir -p ${remote_codex_dir} ${remote_exec_server_dir}"
     docker cp "${codex_binary_path}" "${container_name}:${remote_codex_path}"
     docker exec "${container_name}" sh -lc \
       "chmod +x ${remote_codex_path} && ln -sf ${remote_codex_path} ${remote_codex_linux_sandbox_path}"
@@ -92,7 +98,11 @@ setup_remote_env() {
   fi
 
   export CODEX_TEST_REMOTE_ENV="${container_name}"
-  export CODEX_TEST_REMOTE_CODEX_PATH="${remote_codex_path}"
+  if [[ -n "${remote_codex_path}" ]]; then
+    export CODEX_TEST_REMOTE_CODEX_PATH="${remote_codex_path}"
+  else
+    unset CODEX_TEST_REMOTE_CODEX_PATH
+  fi
 }
 
 wait_for_remote_exec_server_port() {