Implements a fully self-contained BM25 inverted index for full-text search across book content. Includes tokenization with CJK bigram support, pre-computed IDF, and standard BM25 scoring (k1=1.5, b=0.75). No external dependencies beyond basic utilities; can be extracted and used in any TypeScript project needing local full-text search without a database.

A generic persistence middleware for Zustand stores that serializes state to JSON files via a platform-agnostic storage interface. Supports debounced saves, hydration tracking, and async serialization. The pattern is cleanly abstracted from any specific storage backend (desktop uses Tauri plugin, mobile uses expo-file-system), making it reusable in any TypeScript application needing file-based state persistence.

A React Native component that renders Mermaid diagrams inside a WebView with zoom, fullscreen, and SVG export capabilities. Loads Mermaid and D3 from CDN and injects user content safely. The component handles resize events and provides a clean imperative control interface (zoom, fullscreen toggle). Extractable for any mobile app needing client-side diagram rendering without a native library.

A fully featured WebDAV client implemented from scratch using platform fetch, supporting PROPFIND, MKCOL, GET, PUT, DELETE, and MOVE methods. Parses XML responses with regex-based PROPFIND parser (no DOM dependency). Includes path normalization, depth-based directory listing, and error handling. The client is platform-agnostic via the fetch injection pattern and can be used in any JavaScript environment.