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.
npx agentmods add skills/ericrisco/rsc-harness/csharp-dotnetnpx skills add ericrisco/rsc-harness --skill csharp-dotnetgit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote 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.
[](https://agentmods.dev/skills/ericrisco/rsc-harness/csharp-dotnet)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/csharp-dotnet"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/csharp-dotnet.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00089 | $0.03201 |
| Opus 5 | $0.00044 | $0.01600 |
| Sonnet 5 | $0.00018 | $0.00640 |
| Haiku 4.5 | $0.00009 | $0.00320 |
Grade A, and why
csharp-dotnet 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 4d 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.
How it starts
The opening of the file, as written. The whole thing — 273 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Modern C# and .NET services
You write and review C#, ASP.NET Core APIs, and EF Core data access. You own the .NET idioms, the HTTP-contract patterns as expressed in .NET, async correctness, and the .NET-specific quality/security gates. You delegate everything language- agnostic to the right sibling.
Target: .NET 10 (LTS, released 2025-11-11, supported 3 years) with C# 14, EF Core
10, ASP.NET Core 10. .NET 9 / C# 13 is the immediate STS predecessor — still in
support but shorter-lived. Features gate on the target framework moniker (TFM): a
net10.0 project gets C# 14 by default; a net9.0 project caps at C# 13. When you
use a C# 14 feature (field, extension members, null-conditional assignment), say
which TFM it requires.
When NOT to use — delegate
| Situation | Route to |
|---|---|
| Java / Spring Boot backend | spring-boot |
| Node / NestJS TypeScript backend | nestjs |
| Language-agnostic threat modeling, OWASP authz/abuse review | ../secure-coding/SKILL.md |
| Raw Postgres schema/index/query tuning | ../postgresdb/SKILL.md |
| Framework-neutral REST resource taxonomy | api-design |
| Dockerfile / CI pipeline / deploy target | ../deployment/SKILL.md |
| Recording per-project conventions in the workspace wiki | ../harness/SKILL.md |
The .NET expression of an API contract and async correctness live HERE. Resource
naming theory lives in api-design; the JVM and Node counterparts are spring-boot
and nestjs.
Project & solution layout + dotnet CLI
dotnet new sln -n Shop # solution
dotnet new webapi -n Shop.Api # minimal API (default in .NET 10)
dotnet new webapi -n Shop.Api --use-controllers # opt into MVC controllers instead
dotnet new xunit -n Shop.Api.Tests # test project
dotnet sln add Shop.Api Shop.Api.Tests # wire into the solution
dotnet add Shop.Api package Npgsql.EntityFrameworkCore.PostgreSQL
dotnet ef migrations add Initial -p Shop.Api # create a migration
dotnet ef database update -p Shop.Api # apply migrations
dotnet build -warnaserror # compile; analyzers + NRT as errors
dotnet test # run tests
dotnet format # apply style; --verify-no-changes in CI
dotnet publish -c Release # produce deployable output
What ships with it
6 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.
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.
- 4d ago First seen · 273 lines · 89 tokens per session scan A 42331572217e
csharp-dotnet is a skill published in the GitHub repository ericrisco/rsc-harness (60 stars, last pushed yesterday), licensed MIT. It adds 89 tokens to every session and 3,201 once invoked, about $0.0004 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 2026-08-30.
Other skills, from other repositories
csharp-dotnet
C# and .NET development patterns.
nunit-code-style
Use when writing or modifying C# method bodies, type declarations, or non-trivial logic in NUnit source. Covers NUnit's taste-and-judgment conventions — exception construction, simplification, naming intent, StringComparison, non-null check form, and var usage — that aren't already caught at build time.
nunit-api-design
Use when adding or modifying public API surface in NUnit — new or changed constraints, attributes, assertions, helpers, or any type/member visibility change. Covers the conventions NUnit maintainers enforce for types that ship to consumers of the framework.
opentelemetry-net-instrumentation
Provides guidance for implementing OpenTelemetry instrumentation in .NET codebases, covering tracing (Activities/Spans), metrics, logs, naming conventions, error handling, performance, SDK setup, resources, context propagation, and API design best practices.
add-slice
Scaffold a slice in this Vertical Slice Architecture template — one use case in its own folder, with its FastEndpoints endpoint, request, response, validator, and summary, plus the Feature and Group if they don't exist yet, plus tests. Use when the user says "add a slice", "add a use case", "add an endpoint", "add a…
clean-architecture-dotnet
Use when domain logic leaks into API/Infrastructure, project references violate layer boundaries, or you need to decide between CQS (always), CQRS bus (complex domains), and DDD patterns (invariants and events).