Chatbox is a cross-platform desktop AI chat client (Windows/macOS/Linux) built with Electron, React, and TypeScript. It supports 30+ AI providers (OpenAI, Claude, Gemini, DeepSeek, Ollama, etc.) via a unified provider registry and model abstraction layer. The application features agent mode with tool use, sandboxed code execution, MCP server integration, knowledge base RAG, web search, image generation, and a skills marketplace. It uses a hexagonal architecture with ports/adapters in a core package (`@chatbox/core`) that is host-agnostic, and React bindings in `@chatbox/react`. The renderer uses TanStack Router, Zustand/Jotai for state, and Mantine/MUI for UI. The main process handles IPC, OAuth flows, file system sandbox, and analytics. The codebase is large and well-tested (Vitest unit tests, integration tests, contract tests) with a focus on offline-first, local storage, and cross-platform compatibility (desktop, web, mobile via Capacitor). The application is actively maintained with a commercial 'Pro' version that shares code with this open-source Community Edition. Notable engineering patterns include a clean port/adapter separation, in-memory test doubles for all repositories, a session write coordinator that serializes updates and cancels stale queries, a draft tokenization system with web workers, and a provider registry that allows dynamic model discovery. The codebase has some technical debt: multiple UI libraries, legacy migration paths, and commented-out code, but overall demonstrates strong craftsmanship and reusability of its core abstractions.