Add structured asynchronous user input requests (#42178)

## What changed

- Replace `send_user_message_async` with `request_user_input_async`, accepting one or more questions with optional suggested answers while allowing the turn to continue.
- Attach structured question metadata to asynchronous agent messages while retaining readable fallback text, and preserve it through app-server events, thread history, and generated schemas.
- Continue enabling the new tool for model catalogs that advertise either the old or new tool name.

## Testing

- Cover tool registration, question validation, emitted items, continued turn execution, history preservation, and backwards-compatible deserialization.

GitOrigin-RevId: ffc49aebde2e854c3c50a122aa52805fec3fc6b3

codex-rs/app-server-protocol/src/protocol/thread_history.rs

@@ -497,6 +497,7 @@ impl ThreadHistoryBuilder {
             phase: payload.phase.clone(),
             memory_citation: payload.memory_citation.clone().map(Into::into),
             delivery: payload.delivery,
+            questions: payload.questions.clone(),
         });
     }
 
@@ -1657,6 +1658,7 @@ impl From<&PendingTurn> for Turn {
 mod tests {
     use super::*;
     use crate::protocol::v2::AgentMessageDelivery;
+    use crate::protocol::v2::AsyncUserInputQuestion;
     use crate::protocol::v2::CommandExecutionSource;
     use codex_extension_items::ExtensionItem as CoreExtensionItem;
     use codex_extension_items::sleep::SleepItem as CoreSleepItem;
@@ -1759,6 +1761,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::AgentReasoning(AgentReasoningEvent {
                 text: "thinking".into(),
@@ -1779,6 +1782,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
         ];
 
@@ -1818,6 +1822,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }
         );
         assert_eq!(
@@ -1852,6 +1857,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }
         );
     }
@@ -2422,12 +2428,23 @@ mod tests {
     }
 
     #[test]
-    fn preserves_agent_message_phase_and_delivery_in_history() {
+    fn preserves_agent_message_phase_delivery_and_questions_in_history() {
+        let questions = vec![
+            AsyncUserInputQuestion {
+                title: "Which environment?".into(),
+                options: Some(vec!["Staging".into(), "Production".into()]),
+            },
+            AsyncUserInputQuestion {
+                title: "Anything else?".into(),
+                options: None,
+            },
+        ];
         let events = vec![EventMsg::AgentMessage(AgentMessageEvent {
             message: "Final reply".into(),
             phase: Some(CoreMessagePhase::FinalAnswer),
             memory_citation: None,
             delivery: Some(AgentMessageDelivery::Async),
+            questions: Some(questions.clone()),
         })];
 
         let items = events
@@ -2444,6 +2461,7 @@ mod tests {
                 phase: Some(CoreMessagePhase::FinalAnswer),
                 memory_citation: None,
                 delivery: Some(AgentMessageDelivery::Async),
+                questions: Some(questions),
             }
         );
     }
@@ -2554,6 +2572,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::AgentReasoning(AgentReasoningEvent {
                 text: "second summary".into(),
@@ -2603,6 +2622,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::TurnAborted(TurnAbortedEvent {
                 turn_id: Some("turn-1".into()),
@@ -2624,6 +2644,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
         ];
 
@@ -2656,6 +2677,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }
         );
 
@@ -2681,6 +2703,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }
         );
     }
@@ -2701,6 +2724,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::UserMessage(UserMessageEvent {
                 client_id: None,
@@ -2715,6 +2739,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::ThreadRolledBack(ThreadRolledBackEvent { num_turns: 1 }),
             EventMsg::UserMessage(UserMessageEvent {
@@ -2730,6 +2755,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
         ];
 
@@ -2761,6 +2787,7 @@ mod tests {
                     phase: None,
                     memory_citation: None,
                     delivery: None,
+                    questions: None,
                 },
             ]
         );
@@ -2781,6 +2808,7 @@ mod tests {
                     phase: None,
                     memory_citation: None,
                     delivery: None,
+                    questions: None,
                 },
             ]
         );
@@ -2802,6 +2830,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::UserMessage(UserMessageEvent {
                 client_id: None,
@@ -2816,6 +2845,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::ThreadRolledBack(ThreadRolledBackEvent { num_turns: 99 }),
         ];
@@ -3849,6 +3879,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::TurnComplete(TurnCompleteEvent {
                 turn_id: "turn-b".into(),
@@ -4028,6 +4059,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
         ];
 
@@ -4295,6 +4327,7 @@ mod tests {
                 phase: None,
                 memory_citation: None,
                 delivery: None,
+                questions: None,
             }),
             EventMsg::Error(ErrorEvent {
                 misalignment: None,

codex-rs/app-server-protocol/src/protocol/thread_history_projection_tests.rs

@@ -125,6 +125,7 @@ fn projects_completed_canonical_turn_items() {
         phase: None,
         memory_citation: None,
         delivery: None,
+        questions: None,
     });
 
     let user_changes = project(item_completed(thread_id, "turn-1", user_item.clone()));

codex-rs/app-server-protocol/src/protocol/v2/item.rs

@@ -26,6 +26,7 @@ use codex_protocol::approvals::GuardianAssessmentDecisionSource as CoreGuardianA
 use codex_protocol::approvals::GuardianCommandSource as CoreGuardianCommandSource;
 use codex_protocol::items::AgentMessageContent as CoreAgentMessageContent;
 pub use codex_protocol::items::AgentMessageDelivery;
+pub use codex_protocol::items::AsyncUserInputQuestion;
 use codex_protocol::items::CollabAgentTool as CoreCollabAgentTool;
 use codex_protocol::items::CollabAgentToolCallStatus as CoreCollabAgentToolCallStatus;
 use codex_protocol::items::CommandExecutionStatus as CoreCommandExecutionStatus;
@@ -255,6 +256,8 @@ pub enum ThreadItem {
         memory_citation: Option<MemoryCitation>,
         #[serde(default)]
         delivery: Option<AgentMessageDelivery>,
+        #[serde(default)]
+        questions: Option<Vec<AsyncUserInputQuestion>>,
     },
     #[serde(rename_all = "camelCase")]
     #[ts(rename_all = "camelCase")]
@@ -881,6 +884,7 @@ impl From<CoreTurnItem> for ThreadItem {
                     phase: agent.phase,
                     memory_citation: agent.memory_citation.map(Into::into),
                     delivery: agent.delivery,
+                    questions: agent.questions,
                 }
             }
             CoreTurnItem::FunctionCallOutput(output) => ThreadItem::FunctionCallOutput {

codex-rs/app-server-protocol/src/protocol/v2/tests.rs

@@ -3071,6 +3071,7 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
         phase: None,
         memory_citation: None,
         delivery: None,
+        questions: None,
     });
 
     assert_eq!(
@@ -3081,6 +3082,7 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
             phase: None,
             memory_citation: None,
             delivery: None,
+            questions: None,
         }
     );
 
@@ -3100,6 +3102,7 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
             rollout_ids: vec!["rollout-1".to_string()],
         }),
         delivery: None,
+        questions: None,
     });
 
     assert_eq!(
@@ -3118,9 +3121,42 @@ fn core_turn_item_into_thread_item_converts_supported_variants() {
                 thread_ids: vec!["rollout-1".to_string()],
             }),
             delivery: None,
+            questions: None,
         }
     );
 
+    let async_item = ThreadItem::from(TurnItem::AgentMessage(AgentMessageItem {
+        id: "async-1".to_string(),
+        content: vec![AgentMessageContent::Text {
+            text: "Which?".to_string(),
+        }],
+        phase: Some(MessagePhase::FinalAnswer),
+        memory_citation: None,
+        delivery: Some(AgentMessageDelivery::Async),
+        questions: Some(vec![AsyncUserInputQuestion {
+            title: "Which?".to_string(),
+            options: None,
+        }]),
+    }));
+    assert_eq!(
+        serde_json::to_value(&async_item).unwrap(),
+        json!({
+            "type": "agentMessage", "id": "async-1", "text": "Which?", "phase": "final_answer",
+            "memoryCitation": null, "delivery": "async", "questions": [{"title": "Which?", "options": null}]
+        })
+    );
+    let old_item: ThreadItem = serde_json::from_value(json!({
+        "type": "agentMessage", "id": "old-1", "text": "An old message"
+    }))
+    .unwrap();
+    assert!(matches!(
+        old_item,
+        ThreadItem::AgentMessage {
+            questions: None,
+            ..
+        }
+    ));
+
     let reasoning_item = TurnItem::Reasoning(ReasoningItem {
         id: "reasoning-1".to_string(),
         summary_text: vec!["line one".to_string(), "line two".to_string()],