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

# Introduction

Helpers provide additional ways to interact with your bot pipeline. They offer a common interface for working with transports, events, and messages within the context of a specific service.

Since RTVI does not make any assumptions about which services a developer will leverage in their bots, helpers reduce unnecessary functionality in your voice clients and facilitate framework extensibility.

Some examples of where helpers can be useful include:

* LLM message context modificiation
* Direct text-to-speech output
* Multi-lingual workflows
* Custom convenience functions

It’s easiest to think of helpers as wrappers around existing voice client functionality that target a specific service, making your RTVI codebase less verbose.

## Using a helper

Helpers must be imported, defined and registered to you voice client.

Here is an example using the included LLM helper:

```typescript
import {
  LLMHelper,
  LLMHelperEvent
  VoiceMessage,
} from "realtime-ai";

const voiceClient = new VoiceClient({
    services: {
        llm: "openai"
    },
    config: [
        // ...
    ]
});

const llmHelper = new LLMHelper({
    callbacks: {
        onLLMContextUpdate: (messages) => {
            // ...
        }
    }
});

voiceClient.registerHelper("llm", llmHelper);

// Events
voiceClient.on(LLMHelperEvent.LLMContextUpdate, (messages) => console.log(messages));

await llmHelper.appendContext({
    role: "user",
    content: "Tell me a joke!",
 });
```

### Registering a helper

Registering a helper provides it with a reference to your voice client. Helpers must be registered in order to use event and action dispatch / resolution.

`voiceClient.registerHelper(service, helper);`

<ParamField path="service" type="string" required="true">
  [Service](/v01/api-reference/services) targeted by the helper as part of your voice client constructor `services` map.
  An exception is thrown if no matching service can be found.

  Note: targeting services is required for scenarios where a pipeline contains multiple declarations of the same service type. For example, your pipeline may have two or more LLM services registered.
</ParamField>

<ParamField path="helper" type="VoiceClientHelper" required="true">
  A helper subclass instance of `VoiceClientHelper`.
</ParamField>

### Retrieving a helper

The voice client holds a reference to all registered helpers. This can be useful if you do not want to hold / pass a reference across your codebase:

```typescript
const llmHelper = voiceClient.getHelper("llm") as LLMHelper;
```

### Unregistering a helper

A service in your pipeline can currently have reference to a single helper to avoid conflicting action dispatch.

You can unregister a helper from a service like so:

```typescript
voiceClient.unregisterHelper("llm");
```

<Note>
  Unregistering helpers will not delete any references in your own code. Any subsequent attempts to use an unregistered helper against the service name will raise an exception.

  If you register a new helper with the same service name and use a previous helper instance, you may encounter errors.
</Note>

### How are helper messages handled?

The `VoiceClientHelper` base class requires that a helper define a `handleMessage` method.

Any RTVI messages received from the transport that does not match native voice client message types are passed through to your client's registered helpers:

```typescript
public handleMessage(ev: VoiceMessage): void {
    switch(ev.type) {
        case MyHelperMessageType.SOME_MESSAGE:
            this._options.callbacks.onSomeMessage(ev.data);
            break;
            // etc
    }
}
```

<Warning>
  Be mindful of defining a 'default' switch handler if you have multiple
  registered helpers listening for the same message type. Catching them will
  prevent lower order helpers from receiving the message.
</Warning>

***

## Writing helpers

Creating your own helper classes can be useful when you want to create reusable code that targets a specific service (or series of services.)

The abstract `VoiceClientHelper` class is intentionally lightweight to provide as much flexibility to the developer as needed.

A typical helper definition will likely include:

* A constructor
* Callback methods
* Event and message types

A basic implementation of a helper would look like this:

<CodeGroup>
  ```typescript myhelper.ts
  import { 
    VoiceMessage,
    VoiceClientHelper,
    VoiceClientHelperOptions
  } from "realtime-ai";

  // --- Events
  // E.g. voiceClient.on(MyHelperEvents.SomeEvent, (message) => { ... });
  export enum MyHelperEvents {
  SomeEvent = "some-event",
  }

  // --- Message types
  // E.g. await voiceClient.action({ service: "myService", action: MyHelperMessageType.SOME_MESSAGE, arguments: [...]});
  export enum MyHelperMessageType {
  SOME_MESSAGE = "some-message",
  }

  // --- Callbacks
  export type MyHelperCallbacks = Partial<{
  onSomeMessage: (message) => void;
  }>;

  // --- Interface and class
  export interface MyHelperOptions extends VoiceClientHelperOptions {
  callbacks?: MyHelperCallbacks;
  }

  export class LLMHelper extends VoiceClientHelper {
    protected declare _options: MyHelperOptions;

  constructor(options: MyHelperOptions) {
  super(options);
  }

  public handleMessage(ev: VoiceMessage): void {
  switch (ev.type) {
  case MyHelperMessageType.SOME_MESSAGE:
  // dispatch action response etc
  break;
  }
  }
  public getMessageTypes(): string[] {
  return Object.values(MyHelperMessageType) as string[];
  }
  }

  ```

  ```javascript myhelper.js
  // Example MyHelper

  import {
    VoiceMessage,
    VoiceClientHelper,
    VoiceClientHelperOptions
  } from "realtime-ai";

  // --- Events
  // E.g. voiceClient.on(MyHelperEvents.SomeEvent, (message) => { ... });
  export const MyHelperEvents = {
    SomeEvent: "some-event",
  }

  // --- Message types
  export const MyHelperMessageType ={
    SOME_MESSAGE: "some-message",
  }

  // --- Interface and class
  export class LLMHelper extends VoiceClientHelper {
    protected declare _options;

    constructor(options) {
      super(options);
    }

    public handleMessage(ev) {
      switch (ev.type) {
        case MyHelperMessageType.SOME_MESSAGE:
          // dispatch action response etc
          break;
      }
    }

    public getMessageTypes() {
      return Object.values(MyHelperMessageType);
    }
  }
  ```
</CodeGroup>