|list|null $prompt Optional. Initial prompt content. * A string for simple text prompts, * a MessagePart or Message object for * structured content, an array for a * message array shape, or a list of * parts or messages for multi-turn * conversations. Default null. * @return WP_AI_Client_Prompt_Builder The prompt builder instance. */ function wp_ai_client_prompt( $prompt = null ): WP_AI_Client_Prompt_Builder { return new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry(), $prompt ); }