> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xuna.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Personalize each conversation with variables and overrides

> Inject per-session data into your agent's system prompt and override voice, language, or prompt at conversation start for each individual user.

Personalization lets you tailor every conversation to the individual user without creating a separate agent for each use case. You pass data at conversation start, and the platform substitutes it into the system prompt or applies it as a configuration override before the first exchange.

## Dynamic variables

Dynamic variables are placeholders in your system prompt that the platform replaces with real values at the start of each session. Use them to inject user-specific information — names, account tiers, preferences, or any other data your backend holds.

### Syntax

Wrap variable names in double curly braces:

```text system-prompt.txt theme={null}
You are a support agent for {{company_name}}.

The user's name is {{user_name}} and they are on the {{plan_name}} plan.
If they are on the Pro plan, they qualify for priority support.
```

### Passing variable values

Pass variable values when initiating the conversation. The exact method depends on whether you are using signed URLs, conversation tokens, or the WebSocket API directly.

<Tabs>
  <Tab title="Signed URL / WebSocket">
    Pass variables in the `conversation_initiation_client_data` message immediately after the WebSocket connection is established:

    ```javascript client.js theme={null}
    ws.on("open", () => {
      ws.send(JSON.stringify({
        type: "conversation_initiation_client_data",
        dynamic_variables: {
          company_name: "Acme Corp",
          user_name: "Jordan",
          plan_name: "Pro",
        },
      }));
    });
    ```

    If you are using the React SDK, pass dynamic variables when generating the conversation token on your server instead (see the Conversation token tab).
  </Tab>

  <Tab title="Conversation token">
    Pass variables when generating the conversation token on your server:

    ```python server.py theme={null}
    from xuna_ai import XunaAI

    client = XunaAI()

    response = client.conversational_ai.conversations.get_token(
        agent_id="your-agent-id",
        dynamic_variables={
            "company_name": "Acme Corp",
            "user_name": "Jordan",
            "plan_name": "Pro",
        }
    )
    token = response.token
    ```
  </Tab>
</Tabs>

<Warning>
  Do not pass sensitive data (passwords, payment card numbers, SSNs) as dynamic variables. Variable values appear in the conversation context and may be logged. Use [server tools](/configure/tools) to look up sensitive data at runtime instead.
</Warning>

## Session overrides

In addition to dynamic variables, you can override core agent settings for a specific session. Overrides do not change the agent's default configuration — they apply only to the conversation being started.

### Supported overrides

| Override   | Description                                                              |
| ---------- | ------------------------------------------------------------------------ |
| `voice_id` | Replace the agent's default voice with a different one for this session. |
| `prompt`   | Replace the entire system prompt for this session.                       |
| `language` | Set a different language for ASR and TTS for this session.               |

### Applying overrides

<Tabs>
  <Tab title="Conversation token (Python)">
    ```python server.py theme={null}
    from xuna_ai import XunaAI

    client = XunaAI()

    response = client.conversational_ai.conversations.get_token(
        agent_id="your-agent-id",
        conversation_config_override={
            "agent": {
                "prompt": {
                    "prompt": "You are a Spanish-language support agent for Acme Corp."
                },
                "language": "es",
            },
            "tts": {
                "voice_id": "different-voice-id-for-spanish",
            }
        }
    )
    token = response.token
    ```
  </Tab>

  <Tab title="Conversation token (TypeScript)">
    ```typescript server.ts theme={null}
    import { XunaAIClient } from "@xuna-ai/xuna-ai-js";

    const client = new XunaAIClient();

    const response = await client.conversationalAi.conversations.getToken({
      agentId: "your-agent-id",
      conversationConfigOverride: {
        agent: {
          prompt: {
            prompt: "You are a Spanish-language support agent for Acme Corp.",
          },
          language: "es",
        },
        tts: {
          voiceId: "different-voice-id-for-spanish",
        },
      },
    });
    const token = response.token;
    ```
  </Tab>
</Tabs>

## Combining variables and overrides

You can use dynamic variables and overrides together. A common pattern is to use variables for user data and overrides for locale-specific configuration:

```python server.py theme={null}
from xuna_ai import XunaAI

client = XunaAI()

response = client.conversational_ai.conversations.get_token(
    agent_id="your-agent-id",
    dynamic_variables={
        "user_name": user.name,
        "account_balance": str(user.account_balance),
    },
    conversation_config_override={
        "agent": {
            "language": user.preferred_language,
        },
        "tts": {
            "voice_id": voice_id_for_locale(user.preferred_language),
        }
    }
)
token = response.token
```

<Tip>
  Store voice IDs and prompt variants in your database keyed by locale or persona. At session start, look up the right values and pass them as overrides. This keeps your agent logic in code and your agent configuration minimal.
</Tip>