Nuvyn CLI 1.2.0: Spec-Driven .NET MAUI, From a New App or One You Already Have

Nuvyn is a standalone PackAsTool CLI for .NET 10 that facilitates building .NET MAUI apps using a spec-driven approach. It depends on System.CommandLine and Spectre.Console and is MIT licensed. Nuvyn offers two main functions: nuvyn init, which creates a new four-platform MAUI host (Android, iOS, Mac Catalyst, Windows), and nuvyn adopt, which attaches the same slash chain to an existing MAUI app without modifying its original structure.

Nuvyn's main objective is to ensure spec-driven development, where a checked-in specification serves as the source of truth, enabling the code to follow that specification. This approach eliminates the risks associated with chat threads, such as their transient nature, contradictions, and unreviewability by teammates. Instead, Nuvyn writes artifacts into the repository, including a constitution, specification, and plan.

The tool operates by installing a global dotnet tool using the command `dotnet tool install -g NuvyntraLabs.Nuvyn.Cli`. Once installed, users can create a new app by running `nuvyn init` followed by the desired folder name, which will create a new folder and copy an embedded three-project host (MVVMExpress + Lumina UIKit). Users can also specify a coding agent by using the `--agent` flag, with the default being 'cursor'. If the specified folder name already exists, Nuvyn will display an error and exit.

By adopting a spec-driven development approach, Nuvyn narrows the search space for potential feature additions, ensuring that the development process remains focused and efficient. This method helps maintain consistency and clarity throughout the project, ultimately resulting in a more reliable and maintainable application.