Exports a composed middleware chain for Express: request ID generation, structured request logging (with duration, method, path, status), CORS, auth token validation (Bearer token or query parameter), and a centralized error handler. This pattern is self-contained and could be extracted as a reusable middleware library for any Express-based API server.

Implements a generic LRU cache with configurable max size and TTL. Uses a Map for O(1) access and tracks most recent access order. Provides get, set, delete, clear, and size methods. The implementation is standalone and could be reused in any JavaScript/TypeScript project needing a simple in-memory cache.

Provides a function `normalizeLanguageCode` that maps a wide variety of language code aliases (e.g., 'zh-cn', 'chi', 'chinese', 'zho') to a canonical code. The mapping is comprehensive and based on ISO 639-1/2/3 and common variants. This module is self-contained and could be extracted as a standalone language code normalization utility for any multilingual application.

Manages the lifecycle of translation model files: downloads from a remote repository (Mozilla/Bergamot), verifies SHA256 hashes, decompresses fzstd-compressed archives, and caches results. Includes retry logic and progress reporting. The pattern is a reusable model/resource downloader that can be adapted for any project needing to fetch and verify large binary assets.