Cursor rule

1---
2paths:
3  - "**/*.cs"
4  - "**/*.csx"
5---
6# C# Coding Style
7 
8> This file extends [common/coding-style.md](../common/coding-style.md) with C#-specific content.
9 
10## Standards
11 
12- Follow current .NET conventions and enable nullable reference types
13- Prefer explicit access modifiers on public and internal APIs
14- Keep files aligned with the primary type they define
15 
16## Types and Models
17 
18- Prefer `record` or `record struct` for immutable value-like models
19- Use `class` for entities or types with identity and lifecycle
20- Use `interface` for service boundaries and abstractions
21- Avoid `dynamic` in application code; prefer generics or explicit models
22 
23```csharp
24public sealed record UserDto(Guid Id, string Email);
25 
26public interface IUserRepository
27{
28    Task<UserDto?> FindByIdAsync(Guid id, CancellationToken cancellationToken);
29}
30```
31 
32## Immutability
33 
34- Prefer `init` setters, constructor parameters, and immutable collections for shared state
35- Do not mutate input models in-place when producing updated state
36 
37```csharp
38public sealed record UserProfile(string Name, string Email);
39 
40public static UserProfile Rename(UserProfile profile, string name) =>
41    profile with { Name = name };
42```
43 
44## Async and Error Handling
45 
46- Prefer `async`/`await` over blocking calls like `.Result` or `.Wait()`
47- Pass `CancellationToken` through public async APIs
48- Throw specific exceptions and log with structured properties
49 
50```csharp
51public async Task<Order> LoadOrderAsync(
52    Guid orderId,
53    CancellationToken cancellationToken)
54{
55    try
56    {
57        return await repository.FindAsync(orderId, cancellationToken)
58            ?? throw new InvalidOperationException($"Order {orderId} was not found.");
59    }
60    catch (Exception ex)
61    {
62        logger.LogError(ex, "Failed to load order {OrderId}", orderId);
63        throw;
64    }
65}
66```
67 
68## Formatting
69 
70- Use `dotnet format` for formatting and analyzer fixes
71- Keep `using` directives organized and remove unused imports
72- Prefer expression-bodied members only when they stay readable
73