Keep the Windows sandbox command runner hidden (#42801)

## What changed

- Build `codex-command-runner` as a Windows-subsystem binary outside tests.
- Launch non-TTY sandbox commands without a console window.
- Suppress the busy cursor when creating the elevated runner process.

GitOrigin-RevId: fc6b70059add7dea642805030bd508915367fe44

codex-rs/windows-sandbox-rs/src/bin/command_runner/main.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(all(target_os = "windows", not(test)), windows_subsystem = "windows")]
+
 #[cfg(target_os = "windows")]
 mod win;
 

codex-rs/windows-sandbox-rs/src/bin/command_runner/win.rs

@@ -77,9 +77,6 @@ use windows_sys::Win32::System::Threading::PROCESS_INFORMATION;
 use windows_sys::Win32::System::Threading::TerminateProcess;
 use windows_sys::Win32::System::Threading::WaitForSingleObject;
 
-// Kept in sync with codex_exec_server::CODEX_FS_HELPER_ARG1 without introducing
-// a dependency cycle.
-const FS_HELPER_ARG: &str = "--codex-run-as-fs-helper";
 const READ_ACL_MUTEX_NAME: &str = "Local\\CodexSandboxReadAcl";
 const TERMINATION_WAIT_MS: u32 = 5_000;
 const WAIT_TIMEOUT: u32 = 0x0000_0102;
@@ -355,11 +352,7 @@ fn spawn_ipc_process(req: &SpawnRequest) -> Result<IpcSpawnedProcess> {
             &req.env,
             stdin_mode,
             StderrMode::Separate,
-            if req.command.get(1).is_some_and(|arg| arg == FS_HELPER_ARG) {
-                ConsoleMode::NoWindow
-            } else {
-                ConsoleMode::Inherit
-            },
+            ConsoleMode::NoWindow,
             desktop,
             Some(log_dir.as_path()),
         )?;

codex-rs/windows-sandbox-rs/src/elevated/runner_client.rs

@@ -43,6 +43,7 @@ use windows_sys::Win32::System::Threading::CreateProcessWithLogonW;
 use windows_sys::Win32::System::Threading::GetCurrentProcess;
 use windows_sys::Win32::System::Threading::GetCurrentThread;
 use windows_sys::Win32::System::Threading::PROCESS_INFORMATION;
+use windows_sys::Win32::System::Threading::STARTF_FORCEOFFFEEDBACK;
 use windows_sys::Win32::System::Threading::STARTUPINFOW;
 use windows_sys::Win32::System::Threading::TerminateProcess;
 use windows_sys::Win32::System::Threading::WaitForSingleObject;
@@ -350,6 +351,7 @@ pub(crate) fn spawn_runner_transport(
     let password_w = to_wide(&sandbox_creds.password);
     let mut si: STARTUPINFOW = unsafe { std::mem::zeroed() };
     si.cb = std::mem::size_of::<STARTUPINFOW>() as u32;
+    si.dwFlags = STARTF_FORCEOFFFEEDBACK;
     let mut pi: PROCESS_INFORMATION = unsafe { std::mem::zeroed() };
     let env_block: Option<Vec<u16>> = None;