fix(core): restrict modal questions to supported hosts

codex-rs/collaboration-mode-templates/templates/default.md

@@ -8,4 +8,4 @@ Your active mode changes only when new developer instructions with a different `
 
 Use the `request_user_input` tool only when it is listed in the available tools for this turn.
 
-In Default mode, strongly prefer making reasonable assumptions and executing the user's request rather than stopping to ask questions. If you absolutely must ask a question because the answer cannot be discovered from local context and a reasonable assumption would be risky, ask the user directly with a concise plain-text question. Never write a multiple choice question as a textual assistant message.
+In Default mode, strongly prefer making reasonable assumptions and executing the user's request rather than stopping to ask questions. If you absolutely must ask a question because the answer cannot be discovered from local context and a reasonable assumption would be risky, use `request_user_input` when it is available. If the tool is unavailable, ask the user directly with a concise plain-text question. Never write a multiple choice question as a textual assistant message.

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

@@ -568,9 +568,13 @@ fn add_core_utility_tools(context: &CoreToolPlanContext<'_>, planned_tools: &mut
         planned_tools.add(UpdateGoalHandler);
     }
 
-    planned_tools.add(RequestUserInputHandler {
-        available_modes: request_user_input_available_modes(),
-    });
+    if !turn_context.session_source.is_non_root_agent()
+        && !matches!(&turn_context.session_source, SessionSource::Exec)
+    {
+        planned_tools.add(RequestUserInputHandler {
+            available_modes: request_user_input_available_modes(),
+        });
+    }
 
     if features.enabled(Feature::RequestPermissionsTool) {
         planned_tools.add(RequestPermissionsHandler);

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

@@ -442,6 +442,33 @@ async fn host_context_gates_goal_and_agent_job_tools() {
     worker_agent_job.assert_visible_contains(&["spawn_agents_on_csv", "report_agent_job_result"]);
 }
 
+#[tokio::test]
+async fn request_user_input_is_hidden_from_unsupported_session_sources() {
+    let interactive_root = probe(|turn| {
+        turn.session_source = SessionSource::VSCode;
+    })
+    .await;
+    interactive_root.assert_visible_contains(&["request_user_input"]);
+
+    let exec = probe(|turn| {
+        turn.session_source = SessionSource::Exec;
+    })
+    .await;
+    exec.assert_visible_lacks(&["request_user_input"]);
+
+    let sub_agent = probe(|turn| {
+        turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
+            parent_thread_id: Default::default(),
+            depth: 1,
+            agent_path: None,
+            agent_nickname: None,
+            agent_role: None,
+        });
+    })
+    .await;
+    sub_agent.assert_visible_lacks(&["request_user_input"]);
+}
+
 #[tokio::test]
 async fn mcp_and_tool_search_follow_direct_and_deferred_tool_exposure() {
     let direct_mcp = probe_with(
@@ -700,6 +727,7 @@ async fn code_mode_only_exposes_code_executor_and_hides_nested_tools() {
 #[tokio::test]
 async fn code_mode_only_keeps_request_user_input_as_a_direct_modal_tool() {
     let plan = probe(|turn| {
+        turn.session_source = SessionSource::VSCode;
         set_features(turn, &[Feature::CodeMode, Feature::CodeModeOnly]);
     })
     .await;
@@ -897,6 +925,7 @@ async fn multi_agent_v2_namespace_is_ignored_without_provider_namespace_support(
 #[tokio::test]
 async fn code_mode_only_can_expose_namespaced_multi_agent_v2_as_normal_tools() {
     let plan = probe(|turn| {
+        turn.session_source = SessionSource::VSCode;
         set_features(
             turn,
             &[

codex-rs/models-manager/src/collaboration_mode_presets_tests.rs

@@ -30,7 +30,8 @@ fn default_mode_instructions_replace_mode_names_placeholder() {
     assert!(default_instructions.contains(
         "Use the `request_user_input` tool only when it is listed in the available tools"
     ));
-    assert!(
-        default_instructions.contains("ask the user directly with a concise plain-text question")
-    );
+    assert!(default_instructions.contains("use `request_user_input` when it is available"));
+    assert!(default_instructions.contains(
+        "If the tool is unavailable, ask the user directly with a concise plain-text question"
+    ));
 }