Code Modernization — Refactoring Existing Code

These rules apply when refactoring or modernizing existing C# or VB.NET source files. For generating new files from scratch, see the coding-standards skill instead.

Golden rule: Make only high-confidence changes. If a transformation could alter runtime semantics and you are not 100 % certain it is safe, leave the code as-is and add a // TODO: comment explaining the potential improvement.

Scope and Safety

• Default target is .NET 10.0 — verify the project's actual target before applying C# 14 syntax.
• Multi-targeted and .NET Framework files exist — do not blindly apply modern syntax that would break older targets.
• Do not edit files under eng/common/.
• Respect .editorconfig settings.