Function pruneLastMessage

extensions/cli/src/compaction.ts:195–220

(
  chatHistory: ChatHistoryItem[],
)

 * @returns The pruned chat history ending with assistant or tool message
 */
export function pruneLastMessage(
  chatHistory: ChatHistoryItem[],
): ChatHistoryItem[] {
  if (chatHistory.length === 0) {
    return chatHistory;
  }

  if (chatHistory.length === 1) {
    // Only one message - always return empty array
    return [];
  }

  const secondToLastIndex = chatHistory.length - 2;
  const secondToLastItem = chatHistory[secondToLastIndex];

  if (
    secondToLastItem.message.role === "assistant" &&
    (secondToLastItem.message as any).toolCalls?.length > 0
  ) {
    return chatHistory.slice(0, -2);
  } else if (secondToLastItem.message.role === "user") {
    return chatHistory.slice(0, -2);
  }

  return chatHistory.slice(0, -1);
}

export function getHistoryForLLM(
  fullHistory: ChatHistoryItem[],