From f7cb13fe84657d7d1bfd35017548d3099c87aa59 Mon Sep 17 00:00:00 2001
From: Eric Traut <etraut@openai.com>
Date: Sun, 12 Apr 2026 23:48:07 -0700
Subject: [PATCH] Fix shell timeout race on Windows

---
 .../tests/suite/v2/realtime_conversation.rs   |  8 ++--
 codex-rs/core/src/exec.rs                     | 15 ++++---
 codex-rs/core/src/exec_tests.rs               | 45 +++++++++++++++++++
 3 files changed, 59 insertions(+), 9 deletions(-)

diff --git a/codex-rs/app-server/tests/suite/v2/realtime_conversation.rs b/codex-rs/app-server/tests/suite/v2/realtime_conversation.rs
index f4c0f99ae3..d7934193ff 100644
--- a/codex-rs/app-server/tests/suite/v2/realtime_conversation.rs
+++ b/codex-rs/app-server/tests/suite/v2/realtime_conversation.rs
@@ -1888,10 +1888,10 @@ fn realtime_tool_ok_command() -> Vec<String> {
     #[cfg(windows)]
     {
         vec![
-            "powershell.exe".to_string(),
-            "-NoProfile".to_string(),
-            "-Command".to_string(),
-            "[Console]::Write('realtime-tool-ok')".to_string(),
+            "cmd.exe".to_string(),
+            "/D".to_string(),
+            "/C".to_string(),
+            "echo|set /p dummy=realtime-tool-ok".to_string(),
         ]
     }
 
diff --git a/codex-rs/core/src/exec.rs b/codex-rs/core/src/exec.rs
index af39657e00..cc33344265 100644
--- a/codex-rs/core/src/exec.rs
+++ b/codex-rs/core/src/exec.rs
@@ -1241,15 +1241,20 @@ async fn consume_output(
     };
     tokio::pin!(expiration_wait);
     let (exit_status, timed_out) = tokio::select! {
+        biased;
+        _ = &mut expiration_wait => {
+            if let Some(exit_status) = child.try_wait()? {
+                (exit_status, false)
+            } else {
+                kill_child_process_group(&mut child)?;
+                child.start_kill()?;
+                (synthetic_exit_status(EXIT_CODE_SIGNAL_BASE + TIMEOUT_CODE), true)
+            }
+        }
         status_result = child.wait() => {
             let exit_status = status_result?;
             (exit_status, false)
         }
-        _ = &mut expiration_wait => {
-            kill_child_process_group(&mut child)?;
-            child.start_kill()?;
-            (synthetic_exit_status(EXIT_CODE_SIGNAL_BASE + TIMEOUT_CODE), true)
-        }
         _ = tokio::signal::ctrl_c() => {
             kill_child_process_group(&mut child)?;
             child.start_kill()?;
diff --git a/codex-rs/core/src/exec_tests.rs b/codex-rs/core/src/exec_tests.rs
index 937a7d6f80..cfb25d9928 100644
--- a/codex-rs/core/src/exec_tests.rs
+++ b/codex-rs/core/src/exec_tests.rs
@@ -291,6 +291,51 @@ async fn exec_full_buffer_capture_ignores_expiration() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn exec_expiration_observes_already_exited_child_before_timing_out() -> Result<()> {
+    #[cfg(windows)]
+    let command = vec![
+        "cmd.exe".to_string(),
+        "/D".to_string(),
+        "/C".to_string(),
+        "echo|set /p dummy=hello".to_string(),
+    ];
+    #[cfg(not(windows))]
+    let command = vec!["printf".to_string(), "hello".to_string()];
+
+    let cancel_token = CancellationToken::new();
+    cancel_token.cancel();
+    let output = exec(
+        ExecParams {
+            command,
+            cwd: codex_utils_absolute_path::AbsolutePathBuf::current_dir()?,
+            expiration: ExecExpiration::Cancellation(cancel_token),
+            capture_policy: ExecCapturePolicy::ShellTool,
+            env: std::env::vars().collect(),
+            network: None,
+            sandbox_permissions: SandboxPermissions::UseDefault,
+            windows_sandbox_level: WindowsSandboxLevel::Disabled,
+            windows_sandbox_private_desktop: false,
+            justification: None,
+            arg0: None,
+        },
+        SandboxType::None,
+        &SandboxPolicy::DangerFullAccess,
+        &FileSystemSandboxPolicy::unrestricted(),
+        /*windows_sandbox_filesystem_overrides*/ None,
+        NetworkSandboxPolicy::Enabled,
+        /*stdout_stream*/ None,
+        Some(Box::new(|| std::thread::sleep(Duration::from_secs(1)))),
+    )
+    .await?;
+
+    assert_eq!(output.stdout.from_utf8_lossy().text, "hello");
+    assert_eq!(output.exit_status.code(), Some(0));
+    assert!(!output.timed_out);
+
+    Ok(())
+}
+
 #[cfg(unix)]
 #[tokio::test]
 async fn exec_full_buffer_capture_keeps_io_drain_timeout_when_descendant_holds_pipe_open()