Add async delivery metadata to agent messages (#39312)

## What changed

- Add an optional `delivery` field to agent message events and app-server
  `agentMessage` items, with `"async"` identifying a user-visible message sent
  without ending the current turn.
- Preserve the marker through legacy event conversion, thread history
  materialization, replay, and generated JSON and TypeScript schemas.
- Require delivery of async agent message completion notifications on the
  in-process app-server transport.

## Testing

- Cover preservation of async delivery metadata in thread history.
- Cover delivery-required classification for async agent messages.

GitOrigin-RevId: f92ba25de1293ee271404badfdf0d117d6530329

codex-rs/tui/src/app/agent_status_feed_tests.rs

@@ -37,6 +37,7 @@ fn agent_status_uses_bounded_buffered_activity() {
                 text: "Finished checking the focused TUI tests.".to_string(),
                 phase: None,
                 memory_citation: None,
+                delivery: None,
             },
             thread_id: "thread-child".to_string(),
             turn_id: "turn-1".to_string(),

codex-rs/tui/src/app/tests.rs

@@ -3497,6 +3497,7 @@ async fn active_thread_file_change_approval_recovers_buffered_changes() {
                 text: "streaming".to_string(),
                 phase: None,
                 memory_citation: None,
+                delivery: None,
             },
         }),
         /*replay_kind*/ None,
@@ -7235,6 +7236,7 @@ async fn replay_thread_snapshot_replays_turn_history_in_order() {
                             text: "done".to_string(),
                             phase: None,
                             memory_citation: None,
+                            delivery: None,
                         },
                     ],
                     status: TurnStatus::Completed,

codex-rs/tui/src/app/tests/session_lifecycle_requests.rs

@@ -366,6 +366,7 @@ async fn older_pagination_reconciles_review_prompts_across_page_boundaries() ->
             }],
             phase: None,
             memory_citation: None,
+            delivery: None,
         })
     }));
     items.extend([
@@ -554,6 +555,7 @@ async fn transcript_home_loads_every_older_history_page() -> Result<()> {
                 }],
                 phase: None,
                 memory_citation: None,
+                delivery: None,
             }),
             started_at_ms: None,
             completed_at_ms: 0,
@@ -919,6 +921,7 @@ async fn underfilled_scrollback_fetches_older_pages_without_opening_the_transcri
                 }],
                 phase: None,
                 memory_citation: None,
+                delivery: None,
             }),
             started_at_ms: None,
             completed_at_ms: 0,

codex-rs/tui/src/app_server_session.rs

@@ -3360,6 +3360,7 @@ mod tests {
                             text: "assistant reply".to_string(),
                             phase: None,
                             memory_citation: None,
+                            delivery: None,
                         },
                     ],
                     status: TurnStatus::Completed,

codex-rs/tui/src/chatwidget/replay.rs

@@ -94,6 +94,8 @@ impl ChatWidget {
                 text,
                 phase,
                 memory_citation,
+                delivery,
+                ..
             } => {
                 self.on_agent_message_item_completed(
                     AgentMessageItem {
@@ -117,6 +119,7 @@ impl ChatWidget {
                                 rollout_ids: citation.thread_ids,
                             }
                         }),
+                        delivery,
                     },
                     &turn_id,
                     from_replay,

codex-rs/tui/src/chatwidget/tests/app_server.rs

@@ -621,6 +621,7 @@ async fn live_app_server_turn_completed_clears_working_status_after_answer_item(
         text: "Yes. What do you need?".to_string(),
         phase: Some(MessagePhase::FinalAnswer),
         memory_citation: None,
+        delivery: None,
     };
     chat.handle_server_notification(
         ServerNotification::ItemCompleted(ItemCompletedNotification {
@@ -1236,6 +1237,7 @@ async fn live_app_server_turn_completion_repairs_dropped_message_deltas() {
         .to_string(),
         phase: Some(MessagePhase::FinalAnswer),
         memory_citation: None,
+        delivery: None,
     }];
     chat.handle_server_notification(
         ServerNotification::TurnCompleted(TurnCompletedNotification {

codex-rs/tui/src/chatwidget/tests/helpers.rs

@@ -767,6 +767,7 @@ pub(super) fn replay_agent_message(
             text: text.into(),
             phase: Some(MessagePhase::FinalAnswer),
             memory_citation: None,
+            delivery: None,
         },
         "turn-1".to_string(),
         replay_kind,
@@ -919,6 +920,7 @@ pub(super) fn complete_assistant_message(
                 text: text.to_string(),
                 phase,
                 memory_citation: None,
+                delivery: None,
             },
         }),
         /*replay_kind*/ None,

codex-rs/tui/src/chatwidget/tests/history_replay.rs

@@ -332,6 +332,7 @@ async fn replayed_nested_review_prompts_do_not_render_or_seed_composer_history()
                         text: "review result is retained".to_string(),
                         phase: Some(MessagePhase::FinalAnswer),
                         memory_citation: None,
+                        delivery: None,
                     },
                 ],
                 ..app_server_turn(

codex-rs/tui/src/chatwidget/tests/plan_mode.rs

@@ -869,6 +869,7 @@ async fn plan_implementation_popup_skips_replayed_turn_complete() {
                 text: "Plan details".to_string(),
                 phase: Some(MessagePhase::FinalAnswer),
                 memory_citation: None,
+                delivery: None,
             }],
             status: AppServerTurnStatus::Completed,
             error: None,
@@ -907,6 +908,7 @@ async fn plan_implementation_popup_shows_once_when_replay_precedes_live_turn_com
                 text: "Plan details".to_string(),
                 phase: Some(MessagePhase::FinalAnswer),
                 memory_citation: None,
+                delivery: None,
             }],
             status: AppServerTurnStatus::Completed,
             error: None,

codex-rs/tui/src/resume_picker.rs

@@ -6332,6 +6332,7 @@ session_picker_view = "dense"
                         text: String::from("hello from assistant"),
                         phase: None,
                         memory_citation: None,
+                        delivery: None,
                     },
                     ThreadItem::Plan {
                         id: String::from("plan-1"),

codex-rs/tui/src/resume_picker_transcript_preview_tests.rs

@@ -41,6 +41,7 @@ fn rollout_agent_message(text: &str) -> RolloutItem {
         message: text.to_string(),
         phase: None,
         memory_citation: None,
+        delivery: None,
     }))
 }
 
@@ -258,6 +259,7 @@ fn transcript_preview_reverse_scan_stops_before_older_items() {
         text: String::from("one\ntwo\nthree\nfour\nfive\nsix"),
         phase: None,
         memory_citation: None,
+        delivery: None,
     };
     let mut lines = Vec::new();