feat(config) experimental_request_user_input toggle (#24541)

## Summary
Experimental flag to allow toggling `request_user_input`:

```
tools.experimental_request_user_input = false
```

## Testing
- [x] Added unit tests

codex-rs/config/src/config_toml.rs

@@ -87,6 +87,10 @@ const fn default_hide_agent_reasoning() -> Option<bool> {
     Some(false)
 }
 
+const fn default_true() -> bool {
+    true
+}
+
 /// Backward-compatible shape for ChatGPT workspace login restrictions in config.toml.
 #[derive(Serialize, Debug, Clone, PartialEq, JsonSchema)]
 #[serde(untagged)]
@@ -617,6 +621,14 @@ pub struct ToolsToml {
         deserialize_with = "deserialize_optional_web_search_tool_config"
     )]
     pub web_search: Option<WebSearchToolConfig>,
+    pub experimental_request_user_input: Option<ExperimentalRequestUserInput>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema)]
+#[schemars(deny_unknown_fields)]
+pub struct ExperimentalRequestUserInput {
+    #[serde(default = "default_true")]
+    pub enabled: bool,
 }
 
 #[derive(Deserialize)]

codex-rs/core/config.schema.json

@@ -763,6 +763,16 @@
       },
       "type": "object"
     },
+    "ExperimentalRequestUserInput": {
+      "additionalProperties": false,
+      "properties": {
+        "enabled": {
+          "default": true,
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
     "ExternalConfigMigrationPrompts": {
       "additionalProperties": false,
       "description": "Settings for notices we display to users via the tui and app-server clients (primarily the Codex IDE extension). NOTE: these are different from notifications - notices are warnings, NUX screens, acknowledgements, etc.",
@@ -2712,6 +2722,9 @@
     "ToolsToml": {
       "additionalProperties": false,
       "properties": {
+        "experimental_request_user_input": {
+          "$ref": "#/definitions/ExperimentalRequestUserInput"
+        },
         "web_search": {
           "allOf": [
             {

codex-rs/core/src/config/config_tests.rs

@@ -12,6 +12,7 @@ use codex_config::config_toml::AgentRoleToml;
 use codex_config::config_toml::AgentsToml;
 use codex_config::config_toml::AutoReviewToml;
 use codex_config::config_toml::ConfigToml;
+use codex_config::config_toml::ExperimentalRequestUserInput;
 use codex_config::config_toml::ProjectConfig;
 use codex_config::config_toml::RealtimeConfig;
 use codex_config::config_toml::RealtimeToml;
@@ -389,7 +390,13 @@ web_search = true
     )
     .expect("TOML deserialization should succeed");
 
-    assert_eq!(cfg.tools, Some(ToolsToml { web_search: None }));
+    assert_eq!(
+        cfg.tools,
+        Some(ToolsToml {
+            web_search: None,
+            experimental_request_user_input: None,
+        })
+    );
 }
 
 #[test]
@@ -402,7 +409,72 @@ web_search = false
     )
     .expect("TOML deserialization should succeed");
 
-    assert_eq!(cfg.tools, Some(ToolsToml { web_search: None }));
+    assert_eq!(
+        cfg.tools,
+        Some(ToolsToml {
+            web_search: None,
+            experimental_request_user_input: None,
+        })
+    );
+}
+
+#[test]
+fn tools_experimental_request_user_input_defaults_to_enabled() {
+    let cfg: ConfigToml = toml::from_str(
+        r#"
+[tools.experimental_request_user_input]
+"#,
+    )
+    .expect("TOML deserialization should succeed");
+
+    assert_eq!(
+        cfg.tools,
+        Some(ToolsToml {
+            web_search: None,
+            experimental_request_user_input: Some(ExperimentalRequestUserInput { enabled: true }),
+        })
+    );
+}
+
+#[test]
+fn tools_experimental_request_user_input_can_be_disabled() {
+    let cfg: ConfigToml = toml::from_str(
+        r#"
+[tools.experimental_request_user_input]
+enabled = false
+"#,
+    )
+    .expect("TOML deserialization should succeed");
+
+    assert_eq!(
+        cfg.tools,
+        Some(ToolsToml {
+            web_search: None,
+            experimental_request_user_input: Some(ExperimentalRequestUserInput { enabled: false }),
+        })
+    );
+}
+
+#[tokio::test]
+async fn load_config_resolves_experimental_request_user_input_enabled() -> std::io::Result<()> {
+    let codex_home = tempdir()?;
+    let config = Config::load_from_base_config_with_overrides(
+        ConfigToml {
+            tools: Some(ToolsToml {
+                web_search: None,
+                experimental_request_user_input: Some(ExperimentalRequestUserInput {
+                    enabled: false,
+                }),
+            }),
+            ..ConfigToml::default()
+        },
+        ConfigOverrides::default(),
+        codex_home.abs(),
+    )
+    .await?;
+
+    assert!(!config.experimental_request_user_input_enabled);
+    Ok(())
 }
 
 #[test]

codex-rs/core/src/config/mod.rs

@@ -939,6 +939,9 @@ pub struct Config {
     /// Additional parameters for the web search tool when it is enabled.
     pub web_search_config: Option<WebSearchConfig>,
 
+    /// Whether to register the experimental request_user_input tool.
+    pub experimental_request_user_input_enabled: bool,
+
     /// If set to `true`, used only the experimental unified exec tool.
     pub use_experimental_unified_exec_tool: bool,
 
@@ -2205,6 +2208,14 @@ fn resolve_web_search_config(config_toml: &ConfigToml) -> Option<WebSearchConfig
         .map(Into::into)
 }
 
+fn resolve_experimental_request_user_input_enabled(config_toml: &ConfigToml) -> bool {
+    config_toml
+        .tools
+        .as_ref()
+        .and_then(|tools| tools.experimental_request_user_input.as_ref())
+        .is_none_or(|config| config.enabled)
+}
+
 fn resolve_multi_agent_v2_config(config_toml: &ConfigToml) -> MultiAgentV2Config {
     let base = multi_agent_v2_toml_config(config_toml.features.as_ref());
     let default = MultiAgentV2Config::default();
@@ -2916,6 +2927,8 @@ impl Config {
         let web_search_mode =
             resolve_web_search_mode(&cfg, &features).unwrap_or(WebSearchMode::Cached);
         let web_search_config = resolve_web_search_config(&cfg);
+        let experimental_request_user_input_enabled =
+            resolve_experimental_request_user_input_enabled(&cfg);
         let multi_agent_v2 = resolve_multi_agent_v2_config(&cfg);
         let apps_mcp_path_override = if features.enabled(Feature::AppsMcpPathOverride) {
             let base = apps_mcp_path_override_toml_config(cfg.features.as_ref());
@@ -3472,6 +3485,7 @@ impl Config {
             forced_login_method,
             web_search_mode: constrained_web_search_mode.value,
             web_search_config,
+            experimental_request_user_input_enabled,
             use_experimental_unified_exec_tool,
             background_terminal_max_timeout,
             ghost_snapshot,

codex-rs/core/src/tools/spec_plan.rs

@@ -600,9 +600,11 @@ fn add_core_utility_tools(context: &CoreToolPlanContext<'_>, planned_tools: &mut
         planned_tools.add(UpdateGoalHandler);
     }
 
-    planned_tools.add(RequestUserInputHandler {
+    if turn_context.config.experimental_request_user_input_enabled {
-        available_modes: request_user_input_available_modes(features),
+        planned_tools.add(RequestUserInputHandler {
-    });
+            available_modes: request_user_input_available_modes(features),
+        });
+    }
 
     if features.enabled(Feature::RequestPermissionsTool) {
         planned_tools.add(RequestPermissionsHandler);

codex-rs/core/src/tools/spec_plan_tests.rs

@@ -377,6 +377,22 @@ fn apply_patch_accepts_environment_id(spec: &ToolSpec) -> bool {
     }
 }
 
+#[tokio::test]
+async fn request_user_input_tool_respects_experimental_config_gate() {
+    let enabled = probe(|_| {}).await;
+    enabled.assert_visible_contains(&["request_user_input"]);
+    enabled.assert_registered_contains(&["request_user_input"]);
+
+    let disabled = probe(|turn| {
+        update_config(turn, |config| {
+            config.experimental_request_user_input_enabled = false;
+        });
+    })
+    .await;
+    disabled.assert_visible_lacks(&["request_user_input"]);
+    disabled.assert_registered_lacks(&["request_user_input"]);
+}
+
 #[tokio::test]
 async fn shell_family_registers_visible_unified_exec_and_hidden_legacy_shell() {
     let plan = probe(|turn| {

codex-rs/thread-manager-sample/src/main.rs

@@ -265,6 +265,7 @@ fn new_config(model: Option<String>, arg0_paths: Arg0DispatchPaths) -> anyhow::R
         forced_login_method: None,
         web_search_mode: Constrained::allow_any(WebSearchMode::Disabled),
         web_search_config: None,
+        experimental_request_user_input_enabled: true,
         use_experimental_unified_exec_tool: false,
         background_terminal_max_timeout: 300_000,
         ghost_snapshot: GhostSnapshotConfig::default(),