This is a development guide for creating a custom plugin that adds an AI travel itinerary generator to a content management system. It is intended for developers who want to extend their site's functionality with a personalized travel planning tool. The guide provides a complete codebase and step-by-step instructions for integrating AI APIs.

Plugin Structure: The guide includes the full plugin architecture with separate files for settings, request handling, and front-end shortcodes, making it easy to modify and extend. Multi-API Support: The plugin is designed to work with several AI providers, allowing you to configure API keys and choose between different models for cost and performance. Admin Settings: A dedicated settings page lets site administrators securely store API keys, select AI models, and customize the prompt template used for itinerary generation. Front-End Shortcode: A configurable shortcode allows you to place the itinerary generator form anywhere on the site, with options to customize labels, trip types, and the default AI service. Secure Handler: The core handler manages user input validation, secure API communication, and error handling to ensure reliable operation.