Elevated sandbox NUX (#8789)

Elevated Sandbox NUX:

* prompt for elevated sandbox setup when agent mode is selected (via
/approvals or at startup)
* prompt for degraded sandbox if elevated setup is declined or fails
* introduce /elevate-sandbox command to upgrade from degraded
experience.

codex-rs/tui2/src/app_event.rs

@@ -14,6 +14,19 @@ use codex_core::protocol::AskForApproval;
 use codex_core::protocol::SandboxPolicy;
 use codex_protocol::openai_models::ReasoningEffort;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(not(target_os = "windows"), allow(dead_code))]
+pub(crate) enum WindowsSandboxEnableMode {
+    Elevated,
+    Legacy,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(not(target_os = "windows"), allow(dead_code))]
+pub(crate) enum WindowsSandboxFallbackReason {
+    ElevationFailed,
+}
+
 #[allow(clippy::large_enum_variant)]
 #[derive(Debug)]
 pub(crate) enum AppEvent {
@@ -105,10 +118,24 @@ pub(crate) enum AppEvent {
         preset: ApprovalPreset,
     },
 
+    /// Open the Windows sandbox fallback prompt after declining or failing elevation.
+    #[cfg_attr(not(target_os = "windows"), allow(dead_code))]
+    OpenWindowsSandboxFallbackPrompt {
+        preset: ApprovalPreset,
+        reason: WindowsSandboxFallbackReason,
+    },
+
+    /// Begin the elevated Windows sandbox setup flow.
+    #[cfg_attr(not(target_os = "windows"), allow(dead_code))]
+    BeginWindowsSandboxElevatedSetup {
+        preset: ApprovalPreset,
+    },
+
     /// Enable the Windows sandbox feature and switch to Agent mode.
     #[cfg_attr(not(target_os = "windows"), allow(dead_code))]
     EnableWindowsSandboxForAgentMode {
         preset: ApprovalPreset,
+        mode: WindowsSandboxEnableMode,
     },
 
     /// Update the current approval policy in the running app and widget.