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

# Background Messaging

> Vapi SDK lets you silently update the chat history through efficient text message integration. This is particularly useful for background tasks or discreetly logging user interactions.

## Scenario Overview

As a developer you may run into scenarios where a user action, such as pressing a button, needs to be logged in the chat history without overt user involvement. This could be crucial for maintaining conversation context or system logging purposes.

<Steps>
  <Step title="Add a Button to Trigger the Message">
    Add a button to your interface with an `onClick` event handler that will call a function to send the system message:

    ```html
    <button id="log-action" onClick="logUserAction()">Log Action</button>
    ```
  </Step>

  <Step title="Log the Action as a System Message">
    When the button is clicked, the `logUserAction` function will silently insert a system message into the chat history:

    ```js
    function logUserAction() {
      // Function to log the user action
      vapi.send({
        type: "add-message",
        message: {
          role: "system",
          content: "The user has pressed the button, say peanuts",
        },
      });
    }
    ```

    * `vapi.send`: The primary function to interact with your assistant, handling various requests or commands.
    * `type: "add-message"`: Specifies the command to add a new message.
    * `message`: This is the actual message that you want to add to the message history.
      * `role`: "system" Designates the message origin as 'system', ensuring the addition is unobtrusive. Other possible values of role are 'user' | 'assistant' | 'tool' | 'function'
      * `content`: The actual message text to be added.
  </Step>
</Steps>

<Card title="Practical Use Cases">
  * Silent logging of user activities. - Contextual updates in conversations triggered by background
    processes. - Non-intrusive user experience enhancements through additional information provision.
</Card>