Expose system proxy support as an experimental setting (#58157)

## What changed

- Add “System proxy” to `/experimental` for opting into macOS or Windows system proxy settings. Keep `respect_system_proxy` disabled by default.
- Update doctor’s macOS proxy guidance to point to `/experimental` and `codex features enable respect_system_proxy`, and tell users to restart Codex after changing the setting.

## Testing

Add snapshots for the experimental setting and doctor guidance, plus a Responses test verifying that `x-codex-beta-features` includes `respect_system_proxy` only when enabled.

GitOrigin-RevId: caa3e1a7cbe222069f35022b06c59da578b8a4dd

codex-rs/cli/src/doctor/network.rs

@@ -75,6 +75,9 @@ pub(super) async fn checks(
     vec![config_check, network, websocket, reachability]
 }
 
+#[cfg(any(target_os = "macos", test))]
+pub(super) const SYSTEM_PROXY_REMEDIATION: &str = "A macOS system proxy is configured but unused. If your organization requires it, ask your administrator whether to enable the experimental System proxy setting in `/experimental` or with `codex features enable respect_system_proxy`. Restart Codex after changing this setting.";
+
 pub(super) fn check(config: Option<&Config>) -> DoctorCheck {
     let mut details = Vec::new();
     push_proxy_env_details(&mut details);
@@ -163,10 +166,7 @@ pub(super) fn with_system_proxy_remediation(
             )
         })
     {
-        check.remediation = Some(
-            "A macOS system proxy is configured but unused. If your organization requires it, ask your administrator whether to enable the under-development feature with `codex features enable respect_system_proxy`."
-                .to_string(),
-        );
+        check.remediation = Some(SYSTEM_PROXY_REMEDIATION.to_string());
     }
     check
 }

codex-rs/cli/src/doctor/output.rs

@@ -1415,6 +1415,15 @@ Background Server
     #[test]
     fn render_human_report_snapshot_covers_environment_rows() {
         let mut report = sample_report();
+        report.checks.push(
+            DoctorCheck::new(
+                "network.reachability",
+                "network",
+                CheckStatus::Fail,
+                "provider is unreachable",
+            )
+            .remediation(super::super::network::SYSTEM_PROXY_REMEDIATION),
+        );
         report.checks.push(
             DoctorCheck::new("config.load", "config", CheckStatus::Ok, "config loaded")
                 .detail("configured TUI mode: fullscreen"),

codex-rs/cli/src/doctor/snapshots/codex__doctor__output__tests__doctor_human_report_environment_rows.snap

@@ -8,6 +8,7 @@ Notes
    ↑ desktop      build 123 available (ready to install)
    ⚠ terminal     narrow terminal
    ✗ auth         token expired - Run `codex login`.
+   ✗ network      provider is unreachable - A macOS system proxy is configured but unused. If your organization requires it, ask your administrator whether to enable the experimental System proxy setting in `/experimental` or with `codex features enable respect_system_proxy`. Restart Codex after changing this setting.
    ⚠ git          this worktree is not on a Windows Dev Drive - create a trusted Windows Dev Drive: https://learn.microsoft.com/en-us/windows/dev-drive/
    ⚠ security     Microsoft Defender can interfere with Codex. Verify Codex exclusions.
 ─────────────────────────────────────────────────────────────
@@ -65,6 +66,7 @@ Updates
 
 Connectivity
   ✓ network      network environment readable
+  ✗ network      provider is unreachable — A macOS system proxy is configured but unused. If your organization requires it, ask your administrator whether to enable the experimental System proxy setting in `/experimental` or with `codex features enable respect_system_proxy`. Restart Codex after changing this setting.
   ✓ websocket    Responses WebSocket handshake succeeded
   ✓ reachability active provider endpoints are reachable over HTTP
 
@@ -72,7 +74,7 @@ Background Server
   ✓ app-server   background server is not running
 
 ─────────────────────────────────────────────────────────────
-16 ok · 5 notes · 3 warn · 1 fail failed
+16 ok · 6 notes · 3 warn · 2 fail failed
 
 --summary compact output           --all expand truncated lists
 --json redacted report

codex-rs/core/tests/suite/responses_system_proxy.rs

@@ -1,6 +1,7 @@
 use anyhow::Result;
 use codex_features::Feature;
 use codex_models_manager::bundled_models_response;
+use core_test_support::responses;
 use core_test_support::responses::ev_completed;
 use core_test_support::responses::ev_response_created;
 use core_test_support::responses::sse;
@@ -18,6 +19,40 @@ const SYSTEM_PROXY_TEST_SUBPROCESS_ENV_VAR: &str = "CODEX_SYSTEM_PROXY_TEST_SUBP
 const TEST_NAME: &str =
     "suite::responses_system_proxy::regular_responses_turn_honors_respect_system_proxy";
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn responses_beta_header_tracks_system_proxy_opt_in() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    for enabled in [false, true] {
+        let server = MockServer::start().await;
+        let response = responses::mount_sse_once(
+            &server,
+            sse(vec![ev_response_created("resp-1"), ev_completed("resp-1")]),
+        )
+        .await;
+        let mut builder = test_codex().with_config(move |config| {
+            config
+                .features
+                .set_enabled(Feature::RespectSystemProxy, enabled)
+                .expect("test config should allow feature update");
+            config.respect_system_proxy = enabled;
+        });
+        let test = builder.build_with_auto_env(&server).await?;
+        test.submit_turn("hello").await?;
+
+        let request = response.single_request();
+        let beta_features = request.header("x-codex-beta-features").unwrap_or_default();
+        assert_eq!(
+            beta_features
+                .split(',')
+                .any(|feature| feature == "respect_system_proxy"),
+            enabled,
+        );
+    }
+
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn regular_responses_turn_honors_respect_system_proxy() -> Result<()> {
     skip_if_no_network!(Ok(()));

codex-rs/features/src/lib.rs

@@ -1564,7 +1564,11 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::RespectSystemProxy,
         key: "respect_system_proxy",
-        stage: Stage::UnderDevelopment,
+        stage: Stage::Experimental {
+            name: "System proxy",
+            menu_description: "Use macOS or Windows system proxy settings for Codex requests.",
+            announcement: "",
+        },
         default_enabled: false,
     },
     FeatureSpec {

codex-rs/tui/src/bottom_pane/experimental_features_view_tests.rs

@@ -53,6 +53,7 @@ fn experimental_features_display_metadata() {
     for feature in [
         Feature::AnalyticsPlanHistory,
         Feature::LoginShellPackagePath,
+        Feature::RespectSystemProxy,
     ] {
         let stage = feature.stage();
         let (app_tx, _app_rx) = tokio::sync::mpsc::unbounded_channel();

codex-rs/tui/src/bottom_pane/snapshots/codex_tui__bottom_pane__experimental_features_view__tests__experimental_features_respect_system_proxy.snap

@@ -0,0 +1,15 @@
+---
+source: tui/src/bottom_pane/experimental_features_view_tests.rs
+expression: buffer_text(&buffer)
+---
+
+  Experimental features
+  Checked features are configured on. Some experimental features take effect
+  only in new tasks or after restarting the Codex server.
+
+
+› [ ] System proxy  Use macOS or Windows system proxy settings for Codex
+                    requests.
+
+
+  space toggle · enter save · esc save/close