Building Conversational AI with Context Memory in Node.js

Building a conversational AI with memory requires careful context management:

class ConversationManager {
  constructor(options = {}) {
    this.maxTokens = options.maxTokens || 4000;
    this.systemPrompt = options.systemPrompt || 'You are a helpful assistant.';
    this.conversations = new Map();
  }

  getHistory(sessionId) {
    if (!this.conversations.has(sessionId)) {
      this.conversations.set(sessionId, []);
    }
    return this.conversations.get(sessionId);
  }

  async chat(sessionId, userMessage) {
    const history = this.getHistory(sessionId);
    history.push({ role: 'user', content: userMessage });

    // Trim history if too long
    while (this.estimateTokens(history) > this.maxTokens) {
      history.shift();
    }

    const response = await openai.chat.completions.create({
      model: 'gpt-4',
      messages: [
        { role: 'system', content: this.systemPrompt },
        ...history
      ]
    });

    const reply = response.choices[0].message.content;
    history.push({ role: 'assistant', content: reply });
    return reply;
  }

  estimateTokens(messages) {
    return messages.reduce((sum, m) => sum + m.content.length / 4, 0);
  }
}