A guide for building .NET applications in C#, including common patterns for web APIs, databases, testing, security, and monitoring.

Use it to structure ASP.NET Core applications, write EF Core database queries and migrations, design APIs, add messaging or caching, and improve logging and tests.

It helps you make stack-specific implementation choices without relying on generic advice that may not fit .NET 8 or 9.

dotnet-core — Skill for Claude Code and Codex by adonai-labs

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.

Any agent

npx skills add adonai-labs/agent-runway --skill skill-dotnet-core

Clone the repo

git clone --depth 1 https://github.com/adonai-labs/agent-runway

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/adonai-labs/agent-runway/skill-dotnet-core/github.svg)](https://agentmods.dev/skills/adonai-labs/agent-runway/skill-dotnet-core)

Your own site

<a href="https://agentmods.dev/skills/adonai-labs/agent-runway/skill-dotnet-core"><img src="https://agentmods.dev/badge/skills/adonai-labs/agent-runway/skill-dotnet-core/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/adonai-labs/agent-runway/skill-dotnet-core"><img src="https://agentmods.dev/badge/skills/adonai-labs/agent-runway/skill-dotnet-core.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 134 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 916 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 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.

Model	Per session	Once invoked
Fable 5.1	$0.00134	$0.00916
Opus 5.5	$0.00054	$0.00366
Sonnet 5.5	$0.00027	$0.00183
Haiku 4.5	$0.00013	$0.00092

Measured yesterday against content hash b384ea848b90, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

dotnet-core 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.

src/stacks/dotnet/skill-dotnet-core/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

.NET Core

How to invoke

After agent-runway add dotnet, the skill is installed into each configured agent's skills directory as dotnet-core. Use:

Cursor: @dotnet-core or ask a .NET question while editing *.cs (rules auto-attach)
Claude Code / other agents: invoke the dotnet-core skill by name, or ask in context of C# files

Examples:

How should I structure this CQRS handler?
Is this EF Core query likely to cause N+1?
How do I test this application service?
How do I add structured logging with correlation here?

Not sure which skill to use? Start with /start — it classifies intent and routes to the right skill.

Role

Act as a senior .NET engineer with deep experience in ASP.NET Core, EF Core, clean architecture, CQRS, testing, and Azure-hosted .NET systems.

This skill is .NET and C# specific. For system design, trade-off reasoning, and architecture proposals, combine with the architect skill.

What this skill helps with

Applying Clean Architecture, CQRS/MediatR, and feature-first organisation in .NET
EF Core patterns, DbContext design, migrations, and query correctness
Infrastructure integration: messaging, HTTP clients, caching, configuration, secrets
Observability: structured logging, correlation, tracing, metrics, health checks in .NET
ASP.NET Core API design: Minimal APIs, controllers, validation, middleware, auth
Testing: unit, integration, functional, and service-level tests with .NET tooling
Security: input validation, authorisation, secrets management in .NET context

How to use this skill

For implementation questions

Identify what concern the question touches
Load the relevant reference file below
Apply the patterns and rules; highlight divergence with reasons

For implementation reviews

Check against the relevant file for the concern
Surface findings with line-level specifics where possible
Classify as: correct, concern (non-blocking), or violation (blocking)

Read the full file on GitHub · 77 lines

Files

What ships with it

9 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.

yesterday Changed · +1 lines · +14 tokens per session b384ea848b90
2mo ago First seen · 76 lines · 120 tokens per session scan A 08b6db97ff5e

Subscribe to this mod's changes

dotnet-core is a skill published in the GitHub repository adonai-labs/agent-runway (2 stars, last pushed 2d ago), licensed MIT. It adds 134 tokens to every session and 916 once invoked, about $0.0005 per session on Opus 5.5. 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 2026-09-03.

Backend and APIs C# and .NET Claude Code Code review Languages ai ai-agents architecture cursor

dotnet-core next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
dotnet-coreadonai-labs/agent-runway	Skill	2	2d ago	MIT	A	134	Claude Code, Codex
dotnet-aspnetcore-servicemakifbaysal/tasktrooper	Skill	120	16d ago	Apache-2.0	A	48	Claude Code, Codex
aspnet-coreG1Joshi/Agent-Skills	Skill	15	1mo ago	MIT	A	38	Claude Code, Codex
csharpG1Joshi/Agent-Skills	Skill	15	1mo ago	MIT	A	63	Claude Code, Codex
dotnet-techne-csharp-api-designMetalnib/dotnet-episteme-skills	Skill	12	1mo ago	MIT	A	48	Claude Code
dotnet-techne-csharp-concurrency-patternsMetalnib/dotnet-episteme-skills	Skill	12	1mo ago	MIT	A	53	Claude Code
crud-vs-event-sourcingStefanTheCode/dotnet-ai-toolkit	Skill	26	2mo ago	MIT	A	161	Claude Code