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Context

The context object holds information about the currently processed message. It allows you to modify the behavior of your assistant at runtime or alter the message processing flow.

Context can be modified by middlewares during the message processing flow to implement highly flexible logic or rules (e.g., authentication, RAG, etc.).

Properties in Context

export type RequestContext = {
  /** All messages from given conversation */
  messages: Message[];

  /** Convenience reference to the last `messages` item which is the latest `UserMessage`. */
  lastMessage: UserMessage;

  /** Declarations of tools for ai assistant */
  tools: ApplicationTool[];

  /** Storage with references to documents mentioned in the conversation */
  references: ReferenceStorage;

  /** Ids of users who are a part of conversation */
  resolvedEntities: EntityInfo;

  /** Chat model instance */
  chatModel: ChatModel;

  /** Function generating a system prompt (bound to the context) */
  systemPrompt: () => string | null;

  /** 
   * Received partial response update with response streaming.
   * Note: setting this option will switch underlying assistant calls to streaming format. 
   */
  onPartialResponse?: (text: string, delta: string) => void;

  /** Measures and marks for performance tracking */
  performance: PerformanceTimeline;

  /** Container for additional custom properties */
  extras: MessageRequestExtras;
};

To add typing for your custom properties to the context, create a file with the type definition and override the typing.

declare module '@callstack/byorg-core' {
  interface MessageRequestExtras {
    // Here you can add your own properties
    example?: string;
    messagesCount?: number;
    isAdmin?: boolea;
  }
}

export {};
WARNING

All custom properties must be optional, as the current context creation does not support default values for custom objects.

After setting extras, you can access them from the context object:

export const systemPrompt = (context: RequestContext): Promise<string> | string => {
  if (context.extras.isAdmin) {
    return `You are currently talking to an admin.`;
  }

  return `You are talking to user with regular permissions.`;
};

Next, we’ll explore the concept of plugins to understand how to modify the context.