diff --git a/codex-rs/app-server/tests/suite/v2/thread_start.rs b/codex-rs/app-server/tests/suite/v2/thread_start.rs
index 7b9ca39422..4fb4b763b4 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_start.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_start.rs
@@ -20,6 +20,7 @@ use codex_app_server_protocol::ThreadStatus;
 use codex_app_server_protocol::ThreadStatusChangedNotification;
 use codex_config::types::AuthCredentialsStoreMode;
 use codex_core::config::set_project_trust_level;
+use codex_exec_server::ExecServerRuntimePaths;
 use codex_git_utils::resolve_root_git_project_for_trust;
 use codex_login::REFRESH_TOKEN_URL_OVERRIDE_ENV_VAR;
 use codex_protocol::config_types::ServiceTier;
@@ -28,11 +29,16 @@ use codex_protocol::openai_models::ReasoningEffort;
 use pretty_assertions::assert_eq;
 use serde_json::Value;
 use serde_json::json;
+use std::net::TcpListener;
 use std::path::Path;
 use std::path::PathBuf;
 use std::time::Duration;
 use tempfile::TempDir;
+use tokio::task::JoinHandle;
+use tokio::time::Instant;
+use tokio::time::sleep;
 use tokio::time::timeout;
+use tokio_tungstenite::connect_async;
 use wiremock::Mock;
 use wiremock::MockServer;
 use wiremock::ResponseTemplate;
@@ -47,6 +53,7 @@ use super::analytics::wait_for_analytics_payload;
 const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
 const CODEX_EXEC_SERVER_URL_ENV_VAR: &str = "CODEX_EXEC_SERVER_URL";
 const CODEX_EXEC_SERVER_CWD_ENV_VAR: &str = "CODEX_EXEC_SERVER_CWD";
+const EXEC_SERVER_CONNECT_RETRY_INTERVAL: Duration = Duration::from_millis(25);
 
 #[tokio::test]
 async fn thread_start_creates_thread_and_emits_started() -> Result<()> {
@@ -203,6 +210,7 @@ async fn thread_start_uses_remote_default_cwd_when_request_omits_cwd() -> Result
 
     let codex_home = TempDir::new()?;
     create_config_toml_without_approval_policy(codex_home.path(), &server.uri())?;
+    let exec_server = TestExecServer::spawn().await?;
 
     let remote_default_cwd = TempDir::new()?;
     let remote_default_cwd = remote_default_cwd.path().to_string_lossy().into_owned();
@@ -210,7 +218,10 @@ async fn thread_start_uses_remote_default_cwd_when_request_omits_cwd() -> Result
     let mut mcp = McpProcess::new_with_env(
         codex_home.path(),
         &[
-            (CODEX_EXEC_SERVER_URL_ENV_VAR, Some("ws://127.0.0.1:1")),
+            (
+                CODEX_EXEC_SERVER_URL_ENV_VAR,
+                Some(exec_server.websocket_url.as_str()),
+            ),
             (
                 CODEX_EXEC_SERVER_CWD_ENV_VAR,
                 Some(remote_default_cwd.as_str()),
@@ -241,6 +252,7 @@ async fn thread_start_explicit_cwd_overrides_remote_default_cwd() -> Result<()>
 
     let codex_home = TempDir::new()?;
     create_config_toml_without_approval_policy(codex_home.path(), &server.uri())?;
+    let exec_server = TestExecServer::spawn().await?;
 
     let remote_default_cwd = TempDir::new()?;
     let remote_default_cwd = remote_default_cwd.path().to_string_lossy().into_owned();
@@ -250,7 +262,10 @@ async fn thread_start_explicit_cwd_overrides_remote_default_cwd() -> Result<()>
     let mut mcp = McpProcess::new_with_env(
         codex_home.path(),
         &[
-            (CODEX_EXEC_SERVER_URL_ENV_VAR, Some("ws://127.0.0.1:1")),
+            (
+                CODEX_EXEC_SERVER_URL_ENV_VAR,
+                Some(exec_server.websocket_url.as_str()),
+            ),
             (
                 CODEX_EXEC_SERVER_CWD_ENV_VAR,
                 Some(remote_default_cwd.as_str()),
@@ -407,6 +422,64 @@ fn normalize_path_for_comparison(path: impl AsRef<Path>) -> PathBuf {
     path.as_ref().to_path_buf()
 }
 
+struct TestExecServer {
+    websocket_url: String,
+    task: JoinHandle<()>,
+}
+
+impl TestExecServer {
+    async fn spawn() -> Result<Self> {
+        let bind_addr = TcpListener::bind("127.0.0.1:0")?.local_addr()?;
+        let websocket_url = format!("ws://{bind_addr}");
+        let runtime_paths = ExecServerRuntimePaths::new(
+            std::env::current_exe()?,
+            /*codex_linux_sandbox_exe*/ None,
+        )?;
+        let listen_url = websocket_url.clone();
+        let task = tokio::spawn(async move {
+            codex_exec_server::run_main(&listen_url, runtime_paths)
+                .await
+                .expect("test exec-server should run");
+        });
+        wait_for_exec_server(websocket_url.as_str()).await?;
+        Ok(Self {
+            websocket_url,
+            task,
+        })
+    }
+}
+
+impl Drop for TestExecServer {
+    fn drop(&mut self) {
+        self.task.abort();
+    }
+}
+
+async fn wait_for_exec_server(websocket_url: &str) -> Result<()> {
+    let deadline = Instant::now() + DEFAULT_READ_TIMEOUT;
+    loop {
+        match connect_async(websocket_url).await {
+            Ok((mut websocket, _)) => {
+                websocket.close(None).await?;
+                return Ok(());
+            }
+            Err(err) if Instant::now() < deadline => {
+                let is_connection_refused = matches!(
+                    err,
+                    tokio_tungstenite::tungstenite::Error::Io(ref io_err)
+                        if io_err.kind() == std::io::ErrorKind::ConnectionRefused
+                );
+                if is_connection_refused {
+                    sleep(EXEC_SERVER_CONNECT_RETRY_INTERVAL).await;
+                    continue;
+                }
+                return Err(err.into());
+            }
+            Err(err) => return Err(err.into()),
+        }
+    }
+}
+
 #[tokio::test]
 async fn thread_start_tracks_thread_initialized_analytics() -> Result<()> {
     let server = create_mock_responses_server_repeating_assistant("Done").await;