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/core/src/config/mod.rs

@@ -1504,6 +1504,15 @@ impl Config {
         }
         self.forced_auto_mode_downgraded_on_windows = !value;
     }
+
+    pub fn set_windows_elevated_sandbox_globally(&mut self, value: bool) {
+        crate::safety::set_windows_elevated_sandbox_enabled(value);
+        if value {
+            self.features.enable(Feature::WindowsSandboxElevated);
+        } else {
+            self.features.disable(Feature::WindowsSandboxElevated);
+        }
+    }
 }
 
 fn default_review_model() -> String {

codex-rs/core/src/lib.rs

@@ -51,6 +51,7 @@ pub mod token_data;
 mod truncate;
 mod unified_exec;
 mod user_instructions;
+pub mod windows_sandbox;
 pub use model_provider_info::CHAT_WIRE_API_DEPRECATION_SUMMARY;
 pub use model_provider_info::DEFAULT_LMSTUDIO_PORT;
 pub use model_provider_info::DEFAULT_OLLAMA_PORT;
@@ -114,6 +115,8 @@ pub use command_safety::is_safe_command;
 pub use exec_policy::ExecPolicyError;
 pub use exec_policy::load_exec_policy;
 pub use safety::get_platform_sandbox;
+pub use safety::is_windows_elevated_sandbox_enabled;
+pub use safety::set_windows_elevated_sandbox_enabled;
 pub use safety::set_windows_sandbox_enabled;
 // Re-export the protocol types from the standalone `codex-protocol` crate so existing
 // `codex_core::protocol::...` references continue to work across the workspace.

codex-rs/core/src/windows_sandbox.rs

@@ -0,0 +1,49 @@
+use crate::protocol::SandboxPolicy;
+use std::collections::HashMap;
+use std::path::Path;
+
+/// Kill switch for the elevated sandbox NUX on Windows.
+///
+/// When false, revert to the previous sandbox NUX, which only
+/// prompts users to enable the legacy sandbox feature.
+pub const ELEVATED_SANDBOX_NUX_ENABLED: bool = true;
+
+#[cfg(target_os = "windows")]
+pub fn sandbox_setup_is_complete(codex_home: &Path) -> bool {
+    codex_windows_sandbox::sandbox_setup_is_complete(codex_home)
+}
+
+#[cfg(not(target_os = "windows"))]
+pub fn sandbox_setup_is_complete(_codex_home: &Path) -> bool {
+    false
+}
+
+#[cfg(target_os = "windows")]
+pub fn run_elevated_setup(
+    policy: &SandboxPolicy,
+    policy_cwd: &Path,
+    command_cwd: &Path,
+    env_map: &HashMap<String, String>,
+    codex_home: &Path,
+) -> anyhow::Result<()> {
+    codex_windows_sandbox::run_elevated_setup(
+        policy,
+        policy_cwd,
+        command_cwd,
+        env_map,
+        codex_home,
+        None,
+        None,
+    )
+}
+
+#[cfg(not(target_os = "windows"))]
+pub fn run_elevated_setup(
+    _policy: &SandboxPolicy,
+    _policy_cwd: &Path,
+    _command_cwd: &Path,
+    _env_map: &HashMap<String, String>,
+    _codex_home: &Path,
+) -> anyhow::Result<()> {
+    anyhow::bail!("elevated Windows sandbox setup is only supported on Windows")
+}