private recordHistory()

in packages/core/src/core/geminiChat.ts [511:595]
71 lines of code
21 McCabe index (conditional complexity)

  private recordHistory(
    userInput: Content,
    modelOutput: Content[],
    automaticFunctionCallingHistory?: Content[],
  ) {
    const nonThoughtModelOutput = modelOutput.filter(
      (content) => !this.isThoughtContent(content),
    );

    let outputContents: Content[] = [];
    if (
      nonThoughtModelOutput.length > 0 &&
      nonThoughtModelOutput.every((content) => content.role !== undefined)
    ) {
      outputContents = nonThoughtModelOutput;
    } else if (nonThoughtModelOutput.length === 0 && modelOutput.length > 0) {
      // This case handles when the model returns only a thought.
      // We don't want to add an empty model response in this case.
    } else {
      // When not a function response appends an empty content when model returns empty response, so that the
      // history is always alternating between user and model.
      // Workaround for: https://b.corp.google.com/issues/420354090
      if (!isFunctionResponse(userInput)) {
        outputContents.push({
          role: 'model',
          parts: [],
        } as Content);
      }
    }
    if (
      automaticFunctionCallingHistory &&
      automaticFunctionCallingHistory.length > 0
    ) {
      this.history.push(
        ...extractCuratedHistory(automaticFunctionCallingHistory),
      );
    } else {
      this.history.push(userInput);
    }

    // Consolidate adjacent model roles in outputContents
    const consolidatedOutputContents: Content[] = [];
    for (const content of outputContents) {
      if (this.isThoughtContent(content)) {
        continue;
      }
      const lastContent =
        consolidatedOutputContents[consolidatedOutputContents.length - 1];
      if (this.isTextContent(lastContent) && this.isTextContent(content)) {
        // If both current and last are text, combine their text into the lastContent's first part
        // and append any other parts from the current content.
        lastContent.parts[0].text += content.parts[0].text || '';
        if (content.parts.length > 1) {
          lastContent.parts.push(...content.parts.slice(1));
        }
      } else {
        consolidatedOutputContents.push(content);
      }
    }

    if (consolidatedOutputContents.length > 0) {
      const lastHistoryEntry = this.history[this.history.length - 1];
      const canMergeWithLastHistory =
        !automaticFunctionCallingHistory ||
        automaticFunctionCallingHistory.length === 0;

      if (
        canMergeWithLastHistory &&
        this.isTextContent(lastHistoryEntry) &&
        this.isTextContent(consolidatedOutputContents[0])
      ) {
        // If both current and last are text, combine their text into the lastHistoryEntry's first part
        // and append any other parts from the current content.
        lastHistoryEntry.parts[0].text +=
          consolidatedOutputContents[0].parts[0].text || '';
        if (consolidatedOutputContents[0].parts.length > 1) {
          lastHistoryEntry.parts.push(
            ...consolidatedOutputContents[0].parts.slice(1),
          );
        }
        consolidatedOutputContents.shift(); // Remove the first element as it's merged
      }
      this.history.push(...consolidatedOutputContents);
    }
  }