A generic directed graph implementation with typed edges, DFS, BFS, topological sort, and ancestor/descendant queries. It is self-contained (imports only internal types) and could be extracted for any project needing a graph data structure with traversal utilities. Demonstrates clean abstraction over adjacency list and edge types.

A code frame generator that takes source text, location ranges, and optional syntax highlighting, and produces a pretty-printed code snippet with line numbers and caret highlights. It is standalone (no deep internal dependencies) and can be reused in any JavaScript tooling for improved error messages. Demonstrates careful text layout and color handling.

A copy-on-write layered filesystem that combines a writable layer (e.g., MemoryFS) over a readable layer (e.g., NodeFS). It tracks deletions and overrides, and can be used for sandboxed file access or test fixtures. It implements the same `FileSystem` interface as other backends, making it pluggable. Demonstrates a clean proxy pattern for filesystem abstraction.

A standalone Rust parser and serializer for the HTML `srcset` attribute (e.g., `image.jpg 1x, image2.jpg 2x`). It handles pixel density descriptors and width descriptors, and outputs compact serialized strings. This is a well-contained, focused utility that could be extracted into its own crate for any HTML or image processing tool. Demonstrates careful handling of the spec and efficient string processing.

A generic async queue with configurable concurrency. It enqueues functions that return promises, runs up to N at a time, and resolves when all complete. It supports pausing, adding items, and error handling. This is a simple but robust pattern useful in any Node.js project needing throttled async operations. Demonstrates clean implementation of concurrency control without external dependencies.