Function dropTextInBriefTurns

src/components/Messages.tsx:169–206

(messages: T[], briefToolNames: string[])

 * model forgets, text still shows — otherwise the user would see nothing.
 */
export function dropTextInBriefTurns<T extends {
  type: string;
  isMeta?: boolean;
  message?: {
    content: Array<{
      type: string;
      name?: string;
    }>;
  };
}>(messages: T[], briefToolNames: string[]): T[] {
  const nameSet = new Set(briefToolNames);
  // First pass: find which turns (bounded by non-meta user messages) contain
  // a Brief tool_use. Tag each assistant text block with its turn index.
  const turnsWithBrief = new Set<number>();
  const textIndexToTurn: number[] = [];
  let turn = 0;
  for (let i = 0; i < messages.length; i++) {
    const msg = messages[i]!;
    const block = msg.message?.content[0];
    if (msg.type === 'user' && block?.type !== 'tool_result' && !msg.isMeta) {
      turn++;
      continue;
    }
    if (msg.type === 'assistant') {
      if (block?.type === 'text') {
        textIndexToTurn[i] = turn;
      } else if (block?.type === 'tool_use' && block.name && nameSet.has(block.name)) {
        turnsWithBrief.add(turn);
      }
    }
  }
  if (turnsWithBrief.size === 0) return messages;
  // Second pass: drop text blocks whose turn called Brief.
  return messages.filter((_, i) => {
    const t = textIndexToTurn[i];
    return t === undefined || !turnsWithBrief.has(t);
  });
}
type Props = {
  messages: MessageType[];
  tools: Tools;