diff --git a/codex-rs/tui/src/app.rs b/codex-rs/tui/src/app.rs
index 5df79eff17..fadc843683 100644
--- a/codex-rs/tui/src/app.rs
+++ b/codex-rs/tui/src/app.rs
@@ -2921,6 +2921,54 @@ impl App {
                     let _ = preset;
                 }
             }
+            AppEvent::BeginWindowsSandboxLegacySetup { preset } => {
+                #[cfg(target_os = "windows")]
+                {
+                    let policy = preset.sandbox.clone();
+                    let policy_cwd = self.config.cwd.clone();
+                    let command_cwd = policy_cwd.clone();
+                    let env_map: std::collections::HashMap<String, String> =
+                        std::env::vars().collect();
+                    let codex_home = self.config.codex_home.clone();
+
+                    let result = tokio::task::spawn_blocking(move || {
+                        codex_core::windows_sandbox::run_legacy_setup_preflight(
+                            &policy,
+                            policy_cwd.as_path(),
+                            command_cwd.as_path(),
+                            &env_map,
+                            codex_home.as_path(),
+                        )
+                    })
+                    .await
+                    .map_err(|join_err| {
+                        anyhow::anyhow!("legacy Windows sandbox setup task failed: {join_err}")
+                    })?;
+
+                    match result {
+                        Ok(()) => {
+                            self.app_event_tx
+                                .send(AppEvent::EnableWindowsSandboxForAgentMode {
+                                    preset,
+                                    mode: WindowsSandboxEnableMode::Legacy,
+                                });
+                        }
+                        Err(err) => {
+                            tracing::error!(
+                                error = %err,
+                                "failed to run legacy Windows sandbox setup preflight"
+                            );
+                            self.chat_widget.add_error_message(format!(
+                                "Failed to enable the Windows sandbox feature: {err}"
+                            ));
+                        }
+                    }
+                }
+                #[cfg(not(target_os = "windows"))]
+                {
+                    let _ = preset;
+                }
+            }
             AppEvent::BeginWindowsSandboxGrantReadRoot { path } => {
                 #[cfg(target_os = "windows")]
                 {
diff --git a/codex-rs/tui/src/app_event.rs b/codex-rs/tui/src/app_event.rs
index 04968f68d9..a15e0b068e 100644
--- a/codex-rs/tui/src/app_event.rs
+++ b/codex-rs/tui/src/app_event.rs
@@ -294,6 +294,12 @@ pub(crate) enum AppEvent {
         preset: ApprovalPreset,
     },
 
+    /// Begin the non-elevated Windows sandbox setup flow.
+    #[cfg_attr(not(target_os = "windows"), allow(dead_code))]
+    BeginWindowsSandboxLegacySetup {
+        preset: ApprovalPreset,
+    },
+
     /// Begin a non-elevated grant of read access for an additional directory.
     #[cfg_attr(not(target_os = "windows"), allow(dead_code))]
     BeginWindowsSandboxGrantReadRoot {
diff --git a/codex-rs/tui/src/chatwidget.rs b/codex-rs/tui/src/chatwidget.rs
index ef526b3821..72eb278da3 100644
--- a/codex-rs/tui/src/chatwidget.rs
+++ b/codex-rs/tui/src/chatwidget.rs
@@ -4910,9 +4910,8 @@ impl ChatWidget {
                                     .send(AppEvent::BeginWindowsSandboxElevatedSetup { preset });
                             }
                             WindowsSandboxEnableMode::Legacy => {
-                                self.app_event_tx.send(
-                                    AppEvent::EnableWindowsSandboxForAgentMode { preset, mode },
-                                );
+                                self.app_event_tx
+                                    .send(AppEvent::BeginWindowsSandboxLegacySetup { preset });
                             }
                         }
                         return QueueReplayControl::Stop;
@@ -8771,9 +8770,8 @@ impl ChatWidget {
                     name: "Enable experimental sandbox".to_string(),
                     description: None,
                     actions: vec![Box::new(move |tx| {
-                        tx.send(AppEvent::EnableWindowsSandboxForAgentMode {
+                        tx.send(AppEvent::BeginWindowsSandboxLegacySetup {
                             preset: preset_clone.clone(),
-                            mode: WindowsSandboxEnableMode::Legacy,
                         });
                     })],
                     dismiss_on_select: true,
diff --git a/codex-rs/tui/src/chatwidget/tests.rs b/codex-rs/tui/src/chatwidget/tests.rs
index 15a1b97f86..9a01505291 100644
--- a/codex-rs/tui/src/chatwidget/tests.rs
+++ b/codex-rs/tui/src/chatwidget/tests.rs
@@ -9147,6 +9147,22 @@ async fn approvals_elevated_inline_args_start_windows_sandbox_setup() {
     );
 }
 
+#[cfg(target_os = "windows")]
+#[tokio::test]
+async fn approvals_legacy_inline_args_start_windows_sandbox_setup() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.set_windows_sandbox_mode(None);
+    chat.handle_serialized_slash_command(ChatWidget::approval_preset_draft(
+        "auto",
+        &["--enable-windows-sandbox=legacy"],
+    ));
+
+    assert_matches!(
+        rx.try_recv(),
+        Ok(AppEvent::BeginWindowsSandboxLegacySetup { preset }) if preset.id == "auto"
+    );
+}
+
 #[tokio::test]
 async fn permissions_selection_history_snapshot_after_mode_switch() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(None).await;