import { useMemo } from "react";import { inferCheckpointTurnCountByTurnId } from "../session-logic";import type { Thread } from "../types"; export function useTurnDiffSummaries(activeThread: Thread | undefined) {  const turnDiffSummaries = useMemo(() => {    if (!activeThread) {      return [];    }    return activeThread.turnDiffSummaries;  }, [activeThread]);   const inferredCheckpointTurnCountByTurnId = useMemo(    () => inferCheckpointTurnCountByTurnId(turnDiffSummaries),    [turnDiffSummaries],  );   return { turnDiffSummaries, inferredCheckpointTurnCountByTurnId };}