aux is a World of Warcraft Classic (1.13) AddOn that replaces the default auction house interface with an enhanced version. It provides advanced features for searching, posting, and tracking auction history, including customizable filters, automatic stacking and undercutting, historical value calculations, and tooltip enhancements showing item value, vendor prices, and disenchant prospects. The addon is event-driven, using WoW's API to react to auction house events, and employs coroutines for asynchronous operations like scanning auction house pages to avoid blocking the game interface. The architecture is modular, separating concerns into core functionality (caching, scanning, history, tooltip), GUI components, tab-specific logic (auctions, bids, posting, search), and utility libraries. Key systems include a coroutine manager for handling asynchronous tasks without freezing the UI, a schema-based persistence system for saving configuration and data, and a color metatables system for seamless text coloring in the game's interface. The addon demonstrates solid engineering practices with clear separation of concerns, reusable utility modules, and appropriate use of WoW's event and scripting models. While the codebase includes some TODO comments indicating areas for improvement, it remains functional and well-maintained for its target platform. The lack of external dependencies and focus on the static WoW Classic 1.13 API minimizes technical drift concerns. The addon is actively used, as evidenced by its star and issue count, and continues to receive updates.