Hide Windows filesystem helper console windows (#32849)

## What changed

- Add a console mode to the Windows sandbox process launcher.
- Launch `--codex-run-as-fs-helper` subprocesses with `CREATE_NO_WINDOW`.
- Preserve inherited-console behavior for regular sandboxed commands.

GitOrigin-RevId: 927be36b82903b6a5fb1a243ba7f406f9ed85f3f

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

@@ -13,6 +13,7 @@ mod cwd_junction;
 
 use anyhow::Context;
 use anyhow::Result;
+use codex_windows_sandbox::ConsoleMode;
 use codex_windows_sandbox::ErrorPayload;
 use codex_windows_sandbox::ErrorStage;
 use codex_windows_sandbox::ExitPayload;
@@ -77,6 +78,9 @@ 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 WAIT_TIMEOUT: u32 = 0x0000_0102;
 
@@ -339,6 +343,11 @@ 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
+            },
             req.use_private_desktop,
             Some(log_dir.as_path()),
         )?;

codex-rs/windows-sandbox-rs/src/lib.rs

@@ -235,6 +235,8 @@ pub use logging::log_writer;
 #[cfg(target_os = "windows")]
 pub use path_normalization::canonicalize_path;
 #[cfg(target_os = "windows")]
+pub use process::ConsoleMode;
+#[cfg(target_os = "windows")]
 pub use process::PipeSpawnHandles;
 #[cfg(target_os = "windows")]
 pub use process::StderrMode;
@@ -352,6 +354,7 @@ mod windows_impl {
     use super::WindowsSandboxCancellationToken;
     use super::logging::log_failure;
     use super::logging::log_success;
+    use super::process::ConsoleMode;
     use super::process::create_process_as_user;
     use super::sandbox_utils::ensure_codex_home_exists;
     use super::spawn_prep::LegacyAclSids;
@@ -569,6 +572,7 @@ mod windows_impl {
                 &env_map,
                 logs_base_dir,
                 Some((in_r, out_w, err_w)),
+                ConsoleMode::Inherit,
                 use_private_desktop,
             )
         };

codex-rs/windows-sandbox-rs/src/process.rs

@@ -23,6 +23,7 @@ use windows_sys::Win32::System::Console::STD_ERROR_HANDLE;
 use windows_sys::Win32::System::Console::STD_INPUT_HANDLE;
 use windows_sys::Win32::System::Console::STD_OUTPUT_HANDLE;
 use windows_sys::Win32::System::Pipes::CreatePipe;
+use windows_sys::Win32::System::Threading::CREATE_NO_WINDOW;
 use windows_sys::Win32::System::Threading::CREATE_UNICODE_ENVIRONMENT;
 use windows_sys::Win32::System::Threading::CreateProcessAsUserW;
 use windows_sys::Win32::System::Threading::EXTENDED_STARTUPINFO_PRESENT;
@@ -37,6 +38,12 @@ pub struct CreatedProcess {
     _desktop: LaunchDesktop,
 }
 
+/// Controls console creation for pipe-backed child processes.
+pub enum ConsoleMode {
+    Inherit,
+    NoWindow,
+}
+
 pub fn make_env_block(env: &HashMap<String, String>) -> Vec<u16> {
     let mut items: Vec<(String, String)> =
         env.iter().map(|(k, v)| (k.clone(), v.clone())).collect();
@@ -76,6 +83,8 @@ unsafe fn ensure_inheritable_stdio(si: &mut STARTUPINFOW) -> Result<()> {
 /// # Safety
 /// Caller must provide a valid primary token handle (`h_token`) with appropriate access,
 /// and the `argv`, `cwd`, and `env_map` must remain valid for the duration of the call.
+// Low-level CreateProcessAsUserW wrapper mirrors the Windows API shape.
+#[allow(clippy::too_many_arguments)]
 pub unsafe fn create_process_as_user(
     h_token: HANDLE,
     argv: &[String],
@@ -83,6 +92,7 @@ pub unsafe fn create_process_as_user(
     env_map: &HashMap<String, String>,
     logs_base_dir: Option<&Path>,
     stdio: Option<(HANDLE, HANDLE, HANDLE)>,
+    console_mode: ConsoleMode,
     use_private_desktop: bool,
 ) -> Result<CreatedProcess> {
     let cmdline_str = argv_to_command_line(argv);
@@ -120,7 +130,12 @@ pub unsafe fn create_process_as_user(
             attrs.set_handle_list(inherited_handles)?;
             si.lpAttributeList = attrs.as_mut_ptr();
 
-            let creation_flags = CREATE_UNICODE_ENVIRONMENT | EXTENDED_STARTUPINFO_PRESENT;
+            let creation_flags = CREATE_UNICODE_ENVIRONMENT
+                | EXTENDED_STARTUPINFO_PRESENT
+                | match console_mode {
+                    ConsoleMode::Inherit => 0,
+                    ConsoleMode::NoWindow => CREATE_NO_WINDOW,
+                };
             let ok = CreateProcessAsUserW(
                 h_token,
                 std::ptr::null(),
@@ -232,6 +247,7 @@ pub fn spawn_process_with_pipes(
     env_map: &HashMap<String, String>,
     stdin_mode: StdinMode,
     stderr_mode: StderrMode,
+    console_mode: ConsoleMode,
     use_private_desktop: bool,
     logs_base_dir: Option<&Path>,
 ) -> Result<PipeSpawnHandles> {
@@ -275,6 +291,7 @@ pub fn spawn_process_with_pipes(
             env_map,
             logs_base_dir,
             stdio,
+            console_mode,
             use_private_desktop,
         )
     };

codex-rs/windows-sandbox-rs/src/unified_exec/backends/legacy.rs

@@ -4,6 +4,7 @@ use crate::conpty::spawn_conpty_process_as_user;
 use crate::desktop::LaunchDesktop;
 use crate::logging::log_failure;
 use crate::logging::log_success;
+use crate::process::ConsoleMode;
 use crate::process::StderrMode;
 use crate::process::StdinMode;
 use crate::process::read_handle_loop;
@@ -98,6 +99,7 @@ fn spawn_legacy_process(
                 StdinMode::Closed
             },
             StderrMode::Separate,
+            ConsoleMode::Inherit,
             use_private_desktop,
             logs_base_dir,
         )?;