diff --git a/codex-rs/core/src/features.rs b/codex-rs/core/src/features.rs
index 362126b2e4..a894b3353d 100644
--- a/codex-rs/core/src/features.rs
+++ b/codex-rs/core/src/features.rs
@@ -686,8 +686,12 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::DefaultModeRequestUserInput,
         key: "default_mode_request_user_input",
-        stage: Stage::Stable,
-        default_enabled: true,
+        stage: Stage::Experimental {
+            name: "Default mode request_user_input",
+            menu_description: "Allow Codex to use the request_user_input tool in Default mode when it truly cannot proceed safely with a reasonable assumption. Restart Codex after enabling.",
+            announcement: "NEW: Allow request_user_input in Default mode. Enable it in /experimental and restart Codex!",
+        },
+        default_enabled: false,
     },
     FeatureSpec {
         id: Feature::CollaborationModes,
@@ -884,6 +888,28 @@ mod tests {
         assert_eq!(Feature::JsRepl.default_enabled(), false);
     }
 
+    #[test]
+    fn default_mode_request_user_input_is_experimental_and_user_toggleable() {
+        let spec = Feature::DefaultModeRequestUserInput.info();
+        let stage = spec.stage;
+
+        assert!(matches!(stage, Stage::Experimental { .. }));
+        assert_eq!(
+            stage.experimental_menu_name(),
+            Some("Default mode request_user_input")
+        );
+        assert_eq!(
+            stage.experimental_menu_description(),
+            Some(
+                "Allow Codex to use the request_user_input tool in Default mode when it truly cannot proceed safely with a reasonable assumption. Restart Codex after enabling."
+            )
+        );
+        assert_eq!(
+            Feature::DefaultModeRequestUserInput.default_enabled(),
+            false
+        );
+    }
+
     #[test]
     fn image_generation_is_under_development() {
         assert_eq!(Feature::ImageGeneration.stage(), Stage::UnderDevelopment);
diff --git a/codex-rs/core/src/tools/spec.rs b/codex-rs/core/src/tools/spec.rs
index 47250100cb..f0c952e078 100644
--- a/codex-rs/core/src/tools/spec.rs
+++ b/codex-rs/core/src/tools/spec.rs
@@ -2262,9 +2262,7 @@ mod tests {
             create_exec_command_tool(true, false),
             create_write_stdin_tool(),
             PLAN_TOOL.clone(),
-            create_request_user_input_tool(CollaborationModesConfig {
-                default_mode_request_user_input: true,
-            }),
+            create_request_user_input_tool(CollaborationModesConfig::default()),
             create_apply_patch_freeform_tool(),
             ToolSpec::WebSearch {
                 external_web_access: Some(true),
@@ -2383,12 +2381,10 @@ mod tests {
         let request_user_input_tool = find_tool(&tools, "request_user_input");
         assert_eq!(
             request_user_input_tool.spec,
-            create_request_user_input_tool(CollaborationModesConfig {
-                default_mode_request_user_input: true,
-            })
+            create_request_user_input_tool(CollaborationModesConfig::default())
         );
 
-        features.disable(Feature::DefaultModeRequestUserInput);
+        features.enable(Feature::DefaultModeRequestUserInput);
         let tools_config = ToolsConfig::new(&ToolsConfigParams {
             model_info: &model_info,
             features: &features,
@@ -2399,7 +2395,9 @@ mod tests {
         let request_user_input_tool = find_tool(&tools, "request_user_input");
         assert_eq!(
             request_user_input_tool.spec,
-            create_request_user_input_tool(CollaborationModesConfig::default())
+            create_request_user_input_tool(CollaborationModesConfig {
+                default_mode_request_user_input: true,
+            })
         );
     }
 
diff --git a/codex-rs/core/tests/suite/request_user_input.rs b/codex-rs/core/tests/suite/request_user_input.rs
index 2c15f8d6eb..3ef4d4f1c8 100644
--- a/codex-rs/core/tests/suite/request_user_input.rs
+++ b/codex-rs/core/tests/suite/request_user_input.rs
@@ -71,15 +71,21 @@ fn call_output_content_and_success(
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn request_user_input_round_trip_resolves_pending() -> anyhow::Result<()> {
-    request_user_input_round_trip_for_mode(ModeKind::Plan).await
+    request_user_input_round_trip_for_mode(ModeKind::Plan, |_| {}).await
 }
 
-async fn request_user_input_round_trip_for_mode(mode: ModeKind) -> anyhow::Result<()> {
+async fn request_user_input_round_trip_for_mode<C>(
+    mode: ModeKind,
+    configure: C,
+) -> anyhow::Result<()>
+where
+    C: FnOnce(&mut Config) + Send + 'static,
+{
     skip_if_no_network!(Ok(()));
 
     let server = start_mock_server().await;
 
-    let mut builder = test_codex();
+    let mut builder = test_codex().with_config(configure);
     let TestCodex {
         codex,
         cwd,
@@ -294,30 +300,28 @@ async fn request_user_input_rejected_in_execute_mode_alias() -> anyhow::Result<(
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn request_user_input_round_trip_in_default_mode_by_default() -> anyhow::Result<()> {
-    request_user_input_round_trip_for_mode(ModeKind::Default).await
+async fn request_user_input_rejected_in_default_mode_by_default() -> anyhow::Result<()> {
+    assert_request_user_input_rejected("Default", |model| CollaborationMode {
+        mode: ModeKind::Default,
+        settings: Settings {
+            model,
+            reasoning_effort: None,
+            developer_instructions: None,
+        },
+    })
+    .await
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn request_user_input_rejected_in_default_mode_when_feature_disabled() -> anyhow::Result<()> {
-    assert_request_user_input_rejected_with_config(
-        "Default",
-        |model| CollaborationMode {
-            mode: ModeKind::Default,
-            settings: Settings {
-                model,
-                reasoning_effort: None,
-                developer_instructions: None,
-            },
-        },
-        |config| {
-            #[allow(clippy::expect_used)]
-            config
-                .features
-                .disable(Feature::DefaultModeRequestUserInput)
-                .expect("test config should allow feature update");
-        },
-    )
+async fn request_user_input_round_trip_in_default_mode_when_feature_enabled() -> anyhow::Result<()>
+{
+    request_user_input_round_trip_for_mode(ModeKind::Default, |config| {
+        #[allow(clippy::expect_used)]
+        config
+            .features
+            .enable(Feature::DefaultModeRequestUserInput)
+            .expect("test config should allow feature update");
+    })
     .await
 }