Fix turn context reconstruction after backtracking (#14616)

## Summary - reuse rollout reconstruction when applying a backtrack rollback so `reference_context_item` is restored from persisted rollout state - build rollback replay from the flushed rollout items plus the rollback marker, avoiding the extra reread/fallback path - add regression coverage for rollback after compaction so turn-context diffing stays aligned after backtracking Co-authored-by: Codex <noreply@openai.com>
2026-07-01 00:31:56 +08:00 · 2026-03-13 19:28:31 -07:00
parent 69c8a1ef9e
commit bbd329a812
2 changed files with 124 additions and 66 deletions
@@ -1204,6 +1204,99 @@ async fn thread_rollback_recomputes_previous_turn_settings_and_reference_context
    );
 }

+#[tokio::test]
+async fn thread_rollback_restores_cleared_reference_context_item_after_compaction() {
+    let (sess, tc, rx) = make_session_and_context_with_rx().await;
+    attach_rollout_recorder(&sess).await;
+
+    let first_context_item = tc.to_turn_context_item();
+    let first_turn_id = first_context_item
+        .turn_id
+        .clone()
+        .expect("turn context should have turn_id");
+    let compact_turn_id = "compact-turn".to_string();
+    let rolled_back_turn_id = "rolled-back-turn".to_string();
+    let compacted_history = vec![
+        user_message("turn 1 user"),
+        user_message("summary after compaction"),
+    ];
+
+    sess.persist_rollout_items(&[
+        RolloutItem::EventMsg(EventMsg::TurnStarted(
+            codex_protocol::protocol::TurnStartedEvent {
+                turn_id: first_turn_id.clone(),
+                model_context_window: Some(128_000),
+                collaboration_mode_kind: ModeKind::Default,
+            },
+        )),
+        RolloutItem::EventMsg(EventMsg::UserMessage(UserMessageEvent {
+            message: "turn 1 user".to_string(),
+            images: None,
+            local_images: Vec::new(),
+            text_elements: Vec::new(),
+        })),
+        RolloutItem::TurnContext(first_context_item.clone()),
+        RolloutItem::ResponseItem(user_message("turn 1 user")),
+        RolloutItem::ResponseItem(assistant_message("turn 1 assistant")),
+        RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
+            turn_id: first_turn_id,
+            last_agent_message: None,
+        })),
+        RolloutItem::EventMsg(EventMsg::TurnStarted(
+            codex_protocol::protocol::TurnStartedEvent {
+                turn_id: compact_turn_id.clone(),
+                model_context_window: Some(128_000),
+                collaboration_mode_kind: ModeKind::Default,
+            },
+        )),
+        RolloutItem::Compacted(CompactedItem {
+            message: "summary after compaction".to_string(),
+            replacement_history: Some(compacted_history.clone()),
+        }),
+        RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
+            turn_id: compact_turn_id,
+            last_agent_message: None,
+        })),
+        RolloutItem::EventMsg(EventMsg::TurnStarted(
+            codex_protocol::protocol::TurnStartedEvent {
+                turn_id: rolled_back_turn_id.clone(),
+                model_context_window: Some(128_000),
+                collaboration_mode_kind: ModeKind::Default,
+            },
+        )),
+        RolloutItem::EventMsg(EventMsg::UserMessage(UserMessageEvent {
+            message: "turn 2 user".to_string(),
+            images: None,
+            local_images: Vec::new(),
+            text_elements: Vec::new(),
+        })),
+        RolloutItem::TurnContext(TurnContextItem {
+            turn_id: Some(rolled_back_turn_id.clone()),
+            model: "rolled-back-model".to_string(),
+            ..first_context_item.clone()
+        }),
+        RolloutItem::ResponseItem(user_message("turn 2 user")),
+        RolloutItem::ResponseItem(assistant_message("turn 2 assistant")),
+        RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
+            turn_id: rolled_back_turn_id,
+            last_agent_message: None,
+        })),
+    ])
+    .await;
+    sess.replace_history(
+        vec![assistant_message("stale history")],
+        Some(first_context_item),
+    )
+    .await;
+
+    handlers::thread_rollback(&sess, "sub-1".to_string(), 1).await;
+    let rollback_event = wait_for_thread_rolled_back(&rx).await;
+    assert_eq!(rollback_event.num_turns, 1);
+
+    assert_eq!(sess.clone_history().await.raw_items(), compacted_history);
+    assert!(sess.reference_context_item().await.is_none());
+}
+
 #[tokio::test]
 async fn thread_rollback_persists_marker_and_replays_cumulatively() {
    let (sess, tc, rx) = make_session_and_context_with_rx().await;