Method tryCompressChat

packages/core/src/core/client.ts:764–864

(
    prompt_id: string,
    force: boolean = false,
  )

  }

  async tryCompressChat(
    prompt_id: string,
    force: boolean = false,
  ): Promise<ChatCompressionInfo | null> {
    const curatedHistory = this.getChat().getHistory(true);

    // Regardless of `force`, don't do anything if the history is empty.
    if (curatedHistory.length === 0) {
      return null;
    }

    const model = this.config.getModel();

    const { totalTokens: originalTokenCount } =
      await this.getContentGenerator().countTokens({
        model,
        contents: curatedHistory,
      });
    if (originalTokenCount === undefined) {
      console.warn(`Could not determine token count for model ${model}.`);
      return null;
    }

    const contextPercentageThreshold =
      this.config.getChatCompression()?.contextPercentageThreshold;

    // Don't compress if not forced and we are under the limit.
    if (!force) {
      const threshold =
        contextPercentageThreshold ?? COMPRESSION_TOKEN_THRESHOLD;
      if (originalTokenCount < threshold * tokenLimit(model)) {
        return null;
      }
    }

    let compressBeforeIndex = findIndexAfterFraction(
      curatedHistory,
      1 - COMPRESSION_PRESERVE_THRESHOLD,
    );
    // Find the first user message after the index. This is the start of the next turn.
    while (
      compressBeforeIndex < curatedHistory.length &&
      (curatedHistory[compressBeforeIndex]?.role === 'model' ||
        isFunctionResponse(curatedHistory[compressBeforeIndex]))
    ) {
      compressBeforeIndex++;
    }

    const historyToCompress = curatedHistory.slice(0, compressBeforeIndex);
    const historyToKeep = curatedHistory.slice(compressBeforeIndex);

    this.getChat().setHistory(historyToCompress);

    const { text: summary } = await this.getChat().sendMessage(
      {
        message: {
          text: 'First, reason in your scratchpad. Then, generate the <state_snapshot>.',
        },