feat: fix hinting 3 (#19963)

Fix https://github.com/openai/codex/pull/19805#discussion_r3153265562

codex-rs/core/src/agent/control.rs

@@ -394,6 +394,7 @@ impl AgentControl {
             if let Some(parent_thread) = parent_thread.as_ref() {
                 parent_thread
                     .codex
+                    .session
                     .configured_multi_agent_v2_usage_hint_texts()
                     .await
             } else if config.features.enabled(Feature::MultiAgentV2) {

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

@@ -764,22 +764,6 @@ impl Codex {
         state.session_configuration.thread_config_snapshot()
     }
 
-    pub(crate) async fn configured_multi_agent_v2_usage_hint_texts(&self) -> Vec<String> {
-        let state = self.session.state.lock().await;
-        let config = &state.session_configuration.original_config_do_not_use;
-        if !config.features.enabled(Feature::MultiAgentV2) {
-            return Vec::new();
-        }
-
-        [
-            config.multi_agent_v2.root_agent_usage_hint_text.clone(),
-            config.multi_agent_v2.subagent_usage_hint_text.clone(),
-        ]
-        .into_iter()
-        .flatten()
-        .collect()
-    }
-
     pub(crate) fn state_db(&self) -> Option<state_db::StateDbHandle> {
         self.session.state_db()
     }
@@ -857,6 +841,22 @@ impl Session {
         }
     }
 
+    pub(crate) async fn configured_multi_agent_v2_usage_hint_texts(&self) -> Vec<String> {
+        if !self.features.enabled(Feature::MultiAgentV2) {
+            return Vec::new();
+        }
+
+        let state = self.state.lock().await;
+        let config = &state.session_configuration.original_config_do_not_use;
+        [
+            config.multi_agent_v2.root_agent_usage_hint_text.clone(),
+            config.multi_agent_v2.subagent_usage_hint_text.clone(),
+        ]
+        .into_iter()
+        .flatten()
+        .collect()
+    }
+
     fn managed_network_proxy_active_for_permission_profile(
         permission_profile: &PermissionProfile,
     ) -> bool {

codex-rs/core/src/session/tests.rs

@@ -5431,6 +5431,40 @@ async fn build_initial_context_omits_multi_agent_v2_usage_hints_when_feature_dis
     );
 }
 
+#[tokio::test]
+async fn configured_multi_agent_v2_usage_hint_texts_use_effective_enabled_feature_state() {
+    let (mut session, _turn_context) =
+        make_multi_agent_v2_usage_hint_test_session(/*enable_multi_agent_v2*/ false).await;
+    let mut effective_features = Features::with_defaults();
+    effective_features.enable(Feature::MultiAgentV2);
+    Arc::get_mut(&mut session)
+        .expect("session should not be shared")
+        .features = effective_features.into();
+
+    let hint_texts = session.configured_multi_agent_v2_usage_hint_texts().await;
+
+    assert_eq!(
+        hint_texts,
+        vec![
+            "Root guidance.".to_string(),
+            "Subagent guidance.".to_string()
+        ]
+    );
+}
+
+#[tokio::test]
+async fn configured_multi_agent_v2_usage_hint_texts_omit_effectively_disabled_feature() {
+    let (mut session, _turn_context) =
+        make_multi_agent_v2_usage_hint_test_session(/*enable_multi_agent_v2*/ true).await;
+    Arc::get_mut(&mut session)
+        .expect("session should not be shared")
+        .features = Features::with_defaults().into();
+
+    let hint_texts = session.configured_multi_agent_v2_usage_hint_texts().await;
+
+    assert_eq!(hint_texts, Vec::<String>::new());
+}
+
 #[tokio::test]
 async fn build_initial_context_omits_default_image_save_location_with_image_history() {
     let (session, turn_context) = make_session_and_context().await;