Maintaining Historical Dialogue

In a real-time digital human system, the character's behavior, tone, knowledge structure, and multi-turn dialogue "memory" are controlled through two mechanisms:

1、Conversation Item Creation Message (Unidirectional User Memory)

The system supports building context by sending historical user messages one by one, but this method has significant limitations:

conversationHistory.forEach((msg) => {
  if (msg.role === "user") {
    const messageConfig = {
      type: "conversation.item.create",
      item: {
        type: "message",
        role: "user",
        content: [{ type: "input_text", text: msg.content }]
      }
    };
    socket.send(JSON.stringify(messageConfig));
  }
});

⚠️ Limitations:

  • AI-generated historical messages cannot be embedded.

  • The system will not automatically associate with the context of the previous dialogue (e.g., whether AI has already answered).

  • It is recommended to use this in conjunction with prompt injection, and it is only for supplementing user behavior.

The inability to inject AI-generated historical messages is a known bug in the OpenAI Realtime API and not a bug within this system.

2、System Instructions Injection for Context

By using the instructions field in session.update, role definitions and historical context descriptions can be injected. This way, ${messageConfig} can fully retain the dialogue history between the user and AI, which helps to:

  • Maintain semantic coherence.

  • Support the AI's continuous understanding and memory.

  • Support ongoing control of the AI's tone and behavior.

const instructions = `
You are a gentle and patient emotional companion assistant, skilled at listening and guiding.
Please respond in ${userLanguage}.
Welcome message: "${activeCharacter.greeting}"

Historical dialogue:
User: I wasn't feeling very well yesterday.
AI: What happened? Can you tell me about it?
User: I had an argument with my friend...

When the user requests services like image generation, real-time weather queries, etc., it automatically triggers function calls.

Current context: ${messageConfig}
`;

const sessionConfig = {
  type: "session.update",
  session: {
    instructions,
    /* other session configuration */
  }
};
socket.send(JSON.stringify(sessionConfig));

⚠️ Note:

  • The instructions should not be too long (recommended to keep it within 2000 tokens).

  • For large-scale context, a summary integration should be performed.

  • The system's prompt length will directly affect cost consumption; longer system prompts will result in higher per-minute conversation costs.

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