chore: keep request_user_input tool to persist cache on multi-agents (#17009)

codex-rs/core/src/tools/handlers/request_user_input.rs

@@ -5,6 +5,7 @@ use crate::tools::context::ToolPayload;
 use crate::tools::handlers::parse_arguments;
 use crate::tools::registry::ToolHandler;
 use crate::tools::registry::ToolKind;
+use codex_protocol::protocol::SessionSource;
 use codex_protocol::request_user_input::RequestUserInputArgs;
 use codex_tools::REQUEST_USER_INPUT_TOOL_NAME;
 use codex_tools::normalize_request_user_input_args;
@@ -39,6 +40,12 @@ impl ToolHandler for RequestUserInputHandler {
             }
         };
 
+        if matches!(turn.session_source, SessionSource::SubAgent(_)) {
+            return Err(FunctionCallError::RespondToModel(
+                "request_user_input can only be used by the root thread".to_string(),
+            ));
+        }
+
         let mode = session.collaboration_mode().await.mode;
         if let Some(message) =
             request_user_input_unavailable_message(mode, self.default_mode_request_user_input)
@@ -67,3 +74,7 @@ impl ToolHandler for RequestUserInputHandler {
         Ok(FunctionToolOutput::from_text(content, Some(true)))
     }
 }
+
+#[cfg(test)]
+#[path = "request_user_input_tests.rs"]
+mod tests;

codex-rs/core/src/tools/handlers/request_user_input_tests.rs

@@ -0,0 +1,66 @@
+use super::*;
+use crate::codex::make_session_and_context;
+use crate::tools::context::ToolInvocation;
+use crate::tools::context::ToolPayload;
+use crate::turn_diff_tracker::TurnDiffTracker;
+use codex_protocol::ThreadId;
+use codex_protocol::protocol::SubAgentSource;
+use pretty_assertions::assert_eq;
+use serde_json::json;
+use std::sync::Arc;
+use tokio::sync::Mutex;
+
+#[tokio::test]
+async fn multi_agent_v2_request_user_input_rejects_subagent_threads() {
+    let (session, mut turn) = make_session_and_context().await;
+    turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
+        parent_thread_id: ThreadId::new(),
+        depth: 1,
+        agent_path: None,
+        agent_nickname: None,
+        agent_role: None,
+    });
+
+    let result = RequestUserInputHandler {
+        default_mode_request_user_input: true,
+    }
+    .handle(ToolInvocation {
+        session: Arc::new(session),
+        turn: Arc::new(turn),
+        tracker: Arc::new(Mutex::new(TurnDiffTracker::default())),
+        call_id: "call-1".to_string(),
+        tool_name: REQUEST_USER_INPUT_TOOL_NAME.to_string(),
+        tool_namespace: None,
+        payload: ToolPayload::Function {
+            arguments: json!({
+                "questions": [{
+                    "header": "Hdr",
+                    "question": "Pick one",
+                    "id": "pick_one",
+                    "options": [
+                        {
+                            "label": "A",
+                            "description": "A"
+                        },
+                        {
+                            "label": "B",
+                            "description": "B"
+                        }
+                    ]
+                }]
+            })
+            .to_string(),
+        },
+    })
+    .await;
+
+    let Err(err) = result else {
+        panic!("sub-agent request_user_input should fail");
+    };
+    assert_eq!(
+        err,
+        FunctionCallError::RespondToModel(
+            "request_user_input can only be used by the root thread".to_string(),
+        )
+    );
+}

codex-rs/tools/src/tool_config.rs

@@ -105,7 +105,6 @@ pub struct ToolsConfig {
     pub collab_tools: bool,
     pub multi_agent_v2: bool,
     pub hide_spawn_agent_metadata: bool,
-    pub request_user_input: bool,
     pub default_mode_request_user_input: bool,
     pub experimental_supported_tools: Vec<String>,
     pub agent_jobs_tools: bool,
@@ -144,9 +143,8 @@ impl ToolsConfig {
         let include_multi_agent_v2 = features.enabled(Feature::MultiAgentV2);
         let hide_spawn_agent_metadata = features.enabled(Feature::DebugHideSpawnAgentMetadata);
         let include_agent_jobs = features.enabled(Feature::SpawnCsv);
-        let include_request_user_input = !matches!(session_source, SessionSource::SubAgent(_));
         let include_default_mode_request_user_input =
-            include_request_user_input && features.enabled(Feature::DefaultModeRequestUserInput);
+            features.enabled(Feature::DefaultModeRequestUserInput);
         let include_search_tool =
             model_info.supports_search_tool && features.enabled(Feature::ToolSearch);
         let include_tool_suggest = features.enabled(Feature::ToolSuggest)
@@ -222,7 +220,6 @@ impl ToolsConfig {
             collab_tools: include_collab_tools,
             multi_agent_v2: include_multi_agent_v2,
             hide_spawn_agent_metadata,
-            request_user_input: include_request_user_input,
             default_mode_request_user_input: include_default_mode_request_user_input,
             experimental_supported_tools: model_info.experimental_supported_tools.clone(),
             agent_jobs_tools: include_agent_jobs,

codex-rs/tools/src/tool_config_tests.rs

@@ -131,9 +131,10 @@ fn shell_zsh_fork_prefers_shell_command_over_unified_exec() {
 }
 
 #[test]
-fn subagents_disable_request_user_input_and_agent_jobs_workers_opt_in_by_label() {
+fn subagents_keep_request_user_input_mode_config_and_agent_jobs_workers_opt_in_by_label() {
     let model_info = model_info();
     let mut features = Features::with_defaults();
+    features.enable(Feature::DefaultModeRequestUserInput);
     features.enable(Feature::SpawnCsv);
 
     let available_models = Vec::new();
@@ -149,8 +150,7 @@ fn subagents_disable_request_user_input_and_agent_jobs_workers_opt_in_by_label()
         windows_sandbox_level: WindowsSandboxLevel::Disabled,
     });
 
-    assert!(!tools_config.request_user_input);
+    assert!(tools_config.default_mode_request_user_input);
-    assert!(!tools_config.default_mode_request_user_input);
     assert!(tools_config.agent_jobs_tools);
     assert!(tools_config.agent_jobs_worker_tools);
 }

codex-rs/tools/src/tool_registry_plan.rs

@@ -206,7 +206,6 @@ pub fn build_tool_registry_plan(
         plan.register_handler("js_repl_reset", ToolHandlerKind::JsReplReset);
     }
 
-    if config.request_user_input {
     plan.push_spec(
         create_request_user_input_tool(request_user_input_tool_description(
             config.default_mode_request_user_input,
@@ -218,7 +217,6 @@ pub fn build_tool_registry_plan(
         REQUEST_USER_INPUT_TOOL_NAME,
         ToolHandlerKind::RequestUserInput,
     );
-    }
 
     if config.request_permissions_tool_enabled {
         plan.push_spec(

codex-rs/tools/src/tool_registry_plan_tests.rs

@@ -534,9 +534,9 @@ fn test_build_specs_agent_job_worker_tools_enabled() {
             "close_agent",
             "spawn_agents_on_csv",
             "report_agent_job_result",
+            REQUEST_USER_INPUT_TOOL_NAME,
         ],
     );
-    assert_lacks_tool_name(&tools, "request_user_input");
 }
 
 #[test]