Fix stale thread-name resume lookups (#16646)

Addresses #15943

Problem: Name-based resume could stop on a newer session_index entry
whose rollout was never persisted, shadowing an older saved thread with
the same name.

Solution: Materialize rollouts before indexing thread names and make
name lookup skip unresolved entries until it finds a persisted rollout.

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

@@ -590,6 +590,30 @@ async fn live_app_server_invalid_thread_name_update_is_ignored() {
     assert_eq!(chat.thread_name, Some("original name".to_string()));
 }
 
+#[tokio::test]
+async fn live_app_server_thread_name_update_shows_resume_hint() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;
+    let thread_id = ThreadId::new();
+    chat.thread_id = Some(thread_id);
+
+    chat.handle_server_notification(
+        ServerNotification::ThreadNameUpdated(
+            codex_app_server_protocol::ThreadNameUpdatedNotification {
+                thread_id: thread_id.to_string(),
+                thread_name: Some("review-fix".to_string()),
+            },
+        ),
+        /*replay_kind*/ None,
+    );
+
+    assert_eq!(chat.thread_name, Some("review-fix".to_string()));
+    let cells = drain_insert_history(&mut rx);
+    assert_eq!(cells.len(), 1);
+    let rendered = lines_to_single_string(&cells[0]);
+    assert!(rendered.contains("Thread renamed to review-fix"));
+    assert!(rendered.contains("codex resume review-fix"));
+}
+
 #[tokio::test]
 async fn live_app_server_thread_closed_requests_immediate_exit() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;