Skill: Review .NET

Purpose

Review code in the .NET ecosystem (C#, F#) for language and runtime conventions only. Do not define scope (diff vs codebase) or perform security/architecture analysis; those are handled by scope and cognitive skills. Emit a findings list in the standard format for aggregation. Focus on async/await and ConfigureAwait, nullable reference types and NRE avoidance, API and versioning, resources and IDisposable, collections and LINQ, and testability.

Use Cases

• Orchestrated review: Used as the language step when review-code runs scope → language → framework → library → cognitive for .NET projects.
• .NET-only review: When the user wants only language/runtime conventions checked (e.g. after adding a new C# file).
• Pre-PR .NET checklist: Ensure async, nullable, and resource patterns are correct.

When to use: When the code under review is .NET (C#/F#) and the task includes language/runtime quality. Scope (diff vs paths) is determined by the caller or user.

Behavior

Scope of this skill

• Analyze: .NET language and runtime conventions in the given code scope (files or diff provided by the caller). Do not decide scope; accept the code range as input.
• Do not: Perform scope selection (diff vs codebase), security review, or architecture review; do not review non-.NET files unless asked to ignore language.

Review checklist (.NET dimension only)

1. async/await and ConfigureAwait: Correct use of async; ConfigureAwait(false) where appropriate (library code); cancellation token propagation; avoid async void except event handlers.
2. Nullable reference types and NRE: Nullable annotations; null checks and null-forgiving where justified; avoid unnecessary null-forgiving.
3. API and versioning: Public API surface stability; breaking changes; versioning or deprecation strategy for libraries.
4. Resources and IDisposable: Proper use of IDisposable, using statements, and IAsyncDisposable; no leaking handles or streams.
5. Collections and LINQ: Appropriate use of LINQ; allocation and enumeration; avoid multiple enumeration; span/memory where relevant.
6. Testability: Dependency injection and testability; static usage; sealed/overridable where it affects testing.

Tone and references

• Professional and technical: Reference specific locations (file:line). Emit findings with Location, Category, Severity, Title, Description, Suggestion.

Input & Output

Input

• Code scope: Files or directories (or diff) already selected by the user or by the scope skill. This skill does not decide scope; it reviews the provided .NET code for language conventions only.

Output

• Emit zero or more findings in the format defined in Appendix: Output contract.
• Category for this skill is language-dotnet.

Restrictions

• Do not perform security, architecture, or scope selection. Stay within .NET language and runtime conventions.
• Do not give conclusions without specific locations or actionable suggestions.
• Do not review non-.NET code for .NET-specific rules unless the user explicitly includes it (e.g. embedded scripts).

Self-Check

• Was only the .NET language/runtime dimension reviewed (no scope/security/architecture)?
• Are async, nullable, IDisposable, LINQ, and testability covered where relevant?
• Is each finding emitted with Location, Category=language-dotnet, Severity, Title, Description, and optional Suggestion?
• Are issues referenced with file:line?

Examples

Example 1: Async method

• Input: C# method that is async and calls other async methods without passing CancellationToken.
• Expected: Emit a finding (e.g. minor/suggestion) for CancellationToken propagation; reference the method and parameter list. Category = language-dotnet.

Example 2: Nullable and disposal

• Input: C# class that holds an IDisposable and does not implement IDisposable or use using.
• Expected: Emit finding(s) for resource disposal and possibly nullable if the field can be null. Category = language-dotnet.

Edge case: Mixed C# and SQL

• Input: File with C# and embedded SQL strings.
• Expected: Review only the C# parts for .NET conventions (e.g. async, nullable, disposal). Do not emit SQL-injection findings; that is for review-security or review-sql.

Appendix: Output contract

Each finding MUST follow the standard findings format:

Example:

- **Location**: `src/Services/DataLoader.cs:22`
- **Category**: language-dotnet
- **Severity**: minor
- **Title**: Async method does not accept or forward CancellationToken
- **Description**: Long-running or cancellable operations should support cancellation.
- **Suggestion**: Add CancellationToken parameter and pass it to underlying async calls.