What is cratis-csharp-standards?

C# coding conventions for Cratis projects, covering code structure, naming, records, null handling, exceptions, logging, and dependency injection.

Use it when creating or changing C# types in a Cratis project, choosing between records and classes, handling nullable values, or checking formatting and naming.

It gives contributors consistent rules for writing and reviewing Cratis C# code, including project-specific rules for commands and events.

How Cratis/VerticalSlices configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to Cratis/VerticalSlices. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/Cratis/VerticalSlices/main/.ai/skills/cratis-csharp-standards/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/Cratis/VerticalSlices

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/cratis/verticalslices/cratis-csharp-standards/github.svg)](https://agentmods.dev/skills/cratis/verticalslices/cratis-csharp-standards)

Your own site

<a href="https://agentmods.dev/skills/cratis/verticalslices/cratis-csharp-standards"><img src="https://agentmods.dev/badge/skills/cratis/verticalslices/cratis-csharp-standards/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/cratis/verticalslices/cratis-csharp-standards"><img src="https://agentmods.dev/badge/skills/cratis/verticalslices/cratis-csharp-standards.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 101 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 728 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin 100% copy Near-identical to another mod 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.

Model	Per session	Once invoked
Fable 5.1	$0.00101	$0.00728
Opus 5.5	$0.00040	$0.00291
Sonnet 5.5	$0.00020	$0.00146
Haiku 4.5	$0.00010	$0.00073

Measured 1mo ago against content hash 15ebd883f5e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cratis-csharp-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 1mo ago.

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.

Origin

This is a copy

100% identical to cratis-csharp-standards — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.ai/skills/cratis-csharp-standards/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Key rules (quick reference)

Use C# 13 features always — records, primary constructors, pattern matching
var over explicit types — the right side already tells you the type
File-scoped namespace declarations — one less indentation level
using directives: alphabetically sorted, single-line, unused ones removed
No regions — if a file needs them, it needs refactoring
No postfixes: no Async, Impl, Service, Manager, Handler on class names
No Exception suffix on exception types — AuthorNotFound not AuthorNotFoundException
Never use built-in exceptions — always create custom exception types
record for events, commands, read models, concepts — value equality for free
Primary constructors for all types — eliminates field boilerplate
is null / is not null — never == null / != null
Blank line before opening { of every code block
Final return on its own line
Private fields: _camelCase with underscore prefix
Interfaces: I prefix (IMyService)
No [EventType] arguments — the type name is the event identifier
[Command] records define Handle() directly — no separate handler classes

Formatting

// File-scoped namespace (no extra indent)
namespace MyApp.Authors.Registration;

// Alphabetically sorted using directives
using Cratis.Arc.Commands;
using Cratis.Chronicle.Events;
using Microsoft.Extensions.Logging;

// Blank line before { of every block
if (condition)
{
    DoSomething();
}

// Expression-bodied for simple members
public string FullName => $"{FirstName} {LastName}";

// Final return on its own line
public string GetName()
{
    var result = BuildName();

    return result;
}

Naming

Artifact	Convention	Example
Type / method / public member	PascalCase	`RegisterAuthor`, `AuthorId`
Private field	`_camelCase`	`_eventLog`
Local variable	camelCase	`authorId`
Interface	`I` prefix	`IEventLog`
Exception type	No `Exception` suffix	`AuthorNotFound`
Feature folder	Pluralized domain noun	`Authors/`
Concept file	Concept name	`AuthorId.cs`

Read the full file on GitHub · 80 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

1mo ago First seen · 80 lines · 101 tokens per session scan A 15ebd883f5e5

Subscribe to this mod's changes

cratis-csharp-standards is a skill published in the GitHub repository Cratis/VerticalSlices (2 stars, last pushed 1mo ago), licensed MIT. It adds 101 tokens to every session and 728 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to cratis-csharp-standards, differing in 0 lines, and is treated as a copy.

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VerticalSlices: Skill for Claude Code