csharp-nullability

name	csharp-nullability
description	Teach and review C# nullable reference types and null-safety. Use for nullable warnings, nullable annotations, null-forgiving operator, required members, null checks, guard clauses, NullReferenceException prevention, DTOs, EF Core entities, ASP.NET Core model binding, public API null contracts, and migration to nullable-enabled C# projects.
metadata	{"short-description":"C# nullable reference type help"}

C# Nullability

Use $csharp-tutor mode=nullability.

Treat all user text after $csharp-nullability as the nullable reference type concept, warning, code review, migration, API contract, or null-safety question. Use the main csharp-tutor skill as the source of truth.

Load these csharp-tutor references when useful:

• references/nullability-guidance.md
• references/analyzers-guidance.md
• references/common-csharp-pitfalls.md
• references/style-guidance.md
• references/errors-guidance.md
• references/api-design-guidance.md
• references/versioning-guidance.md
• references/official-sources.md
• references/source-citation-rules.md

Default to beginner-friendly explanations that distinguish annotations from runtime validation. Treat ! as a last-resort warning suppression, not a normal fix. When reviewing code, separate correctness risks from cleanup and migration tips.

Standalone Guidance

• Core rule: Keep the answer centered on the concrete nullability decision, failure mode, or contract.
• Avoid: Giving generic C# advice without tying it to the nullability concern.
• Minimal example: public required string Email { get; init; }