What problem does it solve? Developers often misuse modern C# features that are unavailable on their target framework, causing compile errors or inconsistent code. This Skill maps each language feature to the correct TFM and C# version so code always compiles and follows current idioms. ## Core Features & Use Cases - TFM-to-Version Mapping: A quick reference table links net8.0 through net11.0 to C# 12-15 and their key features. - Feature Guidance with Guardrails: Covers records, primary constructors, collection expressions, pattern matching, required members, the field keyword, extension blocks, params collections, Lock, and partial properties, each with version constraints and gotchas. - Multi-Targeting Support: Provides polyfill strategies (PolySharp, Polyfill, conditional compilation) for using newer syntax on older targets. - Use Case: When writing a new service on net8.0, use this Skill to apply primary constructors for DI injection and collection expressions for initialization, while avoiding net10.0-only features like the field keyword. ## Quick Start Ask the assistant to review or write C# code using modern language features appropriate for the project's target framework, running dotnet-version-detection first to determine the TFM.
