wsldl is a Go CLI tool for managing Windows Subsystem for Linux (WSL) distributions. It serves as an advanced launcher and installer that can install distributions from rootfs tarballs or ext4 VHDX images, including HTTP download with caching, resumption, and SHA-256 verification. The tool provides subcommands for running commands in the WSL instance (with optional Windows-to-WSL path translation), backing up (tar, ext4 VHDX, registry export), cleaning (unregistering), configuring settings (default user, WSL version, terminal type, mount flags), and querying configuration values. It also integrates with Windows Terminal and Fluent Terminal as default terminals. The architecture follows a clean CLI monolith pattern in Go, with each subcommand implemented as a module using dependency injection for testability. The WSL and registry APIs are abstracted behind interfaces, allowing comprehensive unit tests via mock implementations on non-Windows platforms. Library packages for HTTP download, file operations (including transparent gzip), Windows console API, Windows Terminal configuration parsing, and CLI error handling are well-isolated and potentially reusable in other projects. While the core functionality is tightly coupled to Windows and WSL, the codebase demonstrates strong engineering practices: comprehensive test coverage, clear separation of concerns, proper error handling, and maintainable build infrastructure (Go modules, cross-compilation, CI/CD with GitHub Actions). The project is actively maintained with frequent commits and responsive issue triage.