csharp-coding-standards

A set of rules for writing consistent C# production code, covering names, file structure, asynchronous code, null handling, dependency injection, logging, result handling, and formatting.

In plain words
What is it for?
Use it when writing or reviewing C# application code, organizing files and namespaces, and applying shared patterns across a project.
Why use it?
It removes disagreements about code style and makes C# projects easier to read, review, and maintain.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/linuxchata/ai-playbook/csharp-coding-standards
Clone the repo
git clone --depth 1 https://github.com/linuxchata/ai-playbook

Made for: Cursor.

Per session 53 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,619 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00053 $0.03619
Opus 5 $0.00026 $0.01809
Sonnet 5 $0.00011 $0.00724
Haiku 4.5 $0.00005 $0.00362

Measured yesterday against content hash c73be6669ad7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

csharp-coding-standards scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/csharp-coding-standards.mdc · 565 lines

How it starts

The opening of the file, as written. The whole thing — 565 lines — stays where its author put it; the contents beside it link to each section on GitHub.

C# Coding Standards

Description

Defines the C# coding standards, patterns, and conventions to be applied consistently across all C# projects. Rules cover naming, structure, async patterns, null handling, dependency injection, logging, result patterns, and formatting. Apply these rules uniformly in all production code.


1. File & Namespace Structure

1.1 File-Scoped Namespaces

Always use file-scoped namespaces:

// ✅ Correct
namespace MyApp.Core.Validators;

internal class OrderValidator { }

// ❌ Wrong
namespace MyApp.Core.Validators
{
    internal class OrderValidator { }
}

1.2 Using Directives

  • Place using directives outside the namespace.
  • Group: System namespaces first, then others ordered alphabetically – separated by a blank line.
  • Use implicit usings where available; add explicit usings only when needed for disambiguation.
using System.Text;
using System.Text.Json;
using Microsoft.Extensions.Logging;
using MyApp.Core.Abstractions;
using MyApp.Domain;

1.3 One Type Per File

Each file contains exactly one top-level type. The file name must match the type name exactly.


2. Naming Conventions

2.1 Types

Kind Convention Example
Classes PascalCase OrderValidator, UserService
Interfaces I prefix + PascalCase IOrderRepository, IUserService
Enums PascalCase OrderStatus, PaymentMethod
Structs PascalCase Money, DateRange
Records PascalCase AppConfiguration, UserSettings

2.2 Members

Kind Convention Example
Public properties PascalCase CreatedAt, TotalAmount
Public methods PascalCase CreateOrder, ValidatePayment
Private fields _camelCase (underscore prefix) _repository, _logger
Constants PascalCase DefaultTimeout, MaxRetryCount
Local variables camelCase orderId, serializedData
Method parameters camelCase cancellationToken, userId
Lambda parameters Short camelCase x =>, e =>, o =>

Read the full file on GitHub · 565 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 565 lines · 53 tokens per session scan A c73be6669ad7

Subscribe to this mod's changes

csharp-coding-standards is a cursor rule published in the GitHub repository linuxchata/ai-playbook (6 stars, last pushed 3mo ago), licensed MIT. It adds 53 tokens to every session and 3,619 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.