Claude HUD is a real-time statusline plugin for Claude Code, the AI coding assistant. It runs as a subprocess and renders a multi-line or compact HUD below the input field, displaying context usage, rate limits, active tools, running agents, todo progress, git/jj status, memory usage, and cost tracking. The system reads session data from stdin (JSON payload) and optionally parses the Claude Code transcript JSONL file for detailed tool/agent activity. It is highly configurable with ~60+ options for layout, colors, visibility, and i18n (English, Simplified/Traditional Chinese). The architecture is modular: a CLI orchestrator (src/index.ts) loads config, runs git/jj/memory/extra-cmd in parallel, then renders via a pure render layer. It uses no external npm dependencies, relying on Node.js built-ins and child processes. The codebase demonstrates strong engineering practices: extensive test coverage (unit, integration, golden snapshot tests), dependency injection for testability, atomic file writes for persistent state, and thorough sanitization of untrusted inputs to prevent terminal injection. It is actively maintained with frequent releases and CI/CD pipelines.