A generic Collection class extending Map with utility methods like filter, find, map, reduce, partition, sweep, and tap. It is self-contained, reusable in any TypeScript project needing an enhanced map with array-like operations, and demonstrates non-obvious skill in combining Map iteration with functional programming patterns.

An abstract BitField class for managing bitwise flags with methods like add, remove, has, serialize, toArray, and static resolve. It is fully generic and can be extracted for any flag-based system (permissions, features, etc.). The implementation handles edge cases like bigint flags and provides a clean API.

A lazy() function that wraps a factory and returns a proxy that defers initialization until first access. It solves circular dependency issues common in large TypeScript monorepos. The implementation is minimal, type-safe, and reusable in any project needing deferred initialization.

A directed graph of audio stream types (Arbitrary, OggOpus, Opus, Raw, WebmOpus) with weighted edges representing transcoding costs. It finds the optimal conversion path between input and output formats using Dijkstra-like logic. This is a non-obvious, reusable pattern for any media pipeline that needs format negotiation.

A request handler that implements Discord's rate limit algorithm with global and per-bucket limits, sublimit detection, retry logic, and hash sweeping. It is tightly coupled to Discord's API but the pattern of sequential request queuing with rate limit awareness is reusable for any API client needing robust throttling.