Gopeed is a high-performance, cross-platform download manager written in Go with a Flutter frontend. It supports HTTP/HTTPS, BitTorrent, Magnet links, ed2k, and HLS streaming protocols. The backend provides a REST API, CLI, and an MCP server for AI agent integration. The frontend is a full-featured Flutter app for desktop (Windows, macOS, Linux), mobile (Android, iOS), and web. Key features include multi-connection downloads with slow-start and work-stealing, a JavaScript extension system (goja) with polyfills for fetch, XHR, Blob, and streams, archive extraction (zip, 7z, rar), webhook/script notifications, and browser impersonation via TLS fingerprinting. The architecture is modular: protocol-specific fetchers implement a common interface, the download engine manages task lifecycle and persistence (BoltDB), and the UI communicates via RPC or FFI. The codebase is well-tested with extensive integration tests and includes a legacy Flutter UI (ui/flutter_old) alongside the current one, indicating an ongoing migration from GetX to Riverpod.