csharp-scripts

csharp-scripts is an official .NET skill for running file-based C# apps with the .NET CLI when a user explicitly wants to try C#/.NET code without scaffolding a full project. It solves the friction of quick C# experimentation: instead of creating a .csproj and solution, the user writes a single entry-point .cs file with top-level statements and runs it directly with `dotnet hello.cs`, which builds, caches, and executes automatically. It is scoped deliberately — for language/API experiments, prototypes, and small utilities — and explicitly not for language-agnostic throwaway scripts, generic computations, full projects, or integration into existing solutions.

The workflow verifies the SDK version (file-based apps require .NET 10+, with multi-file `#:include`/`#:exclude` needing SDK 10.0.300+), then writes the entry-point file and runs it, passing arguments after `--`. Its core capability is a set of `#:` directives placed at the top of the file: `#:package` for NuGet references (with version pinning), `#:property` for arbitrary MSBuild properties and expressions, `#:project` for project references, `#:ref` for compiling a referenced .cs file as a separate assembly, `#:sdk` for SDK selection (e.g. Microsoft.NET.Sdk.Web), and `#:include`/`#:exclude` for composing multi-file apps. Directives are transitive, so helper files can declare their own.

The target users are C# and .NET developers who want a fast, low-ceremony way to test ideas, prototype logic before integrating it, or build a small helper from a handful of files. It is a single-file documentation skill (MIT-licensed) that guides the agent through the modern file-based-app feature set, including guidance to place files outside existing project directories and to add a shebang for Unix executability.