async-hygiene

async-hygiene is a skill for Claude Code, Codex from cwoodruff/dotnet-claude-code-kit. It costs 57 tokens per session (389 once invoked), scanned A, a copy of async-hygiene, MIT.

A C# code checker and fixer for common async/await mistakes, where asynchronous work is started without properly waiting for it or handling cancellation and errors.

In plain words
What is it for?
Use it to scan a solution for blocking calls, async void methods, missing cancellation tokens, fire-and-forget tasks, unnecessary Task.Run calls, and blocking I/O.
Why use it?
It helps prevent blocked threads, deadlocks, thread-pool exhaustion, unobserved failures, and unreliable background work.

Skill for Claude CodeCodex

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 skills/cwoodruff/dotnet-claude-code-kit/async-hygiene
Any agent
npx skills add cwoodruff/dotnet-claude-code-kit --skill async-hygiene
Clone the repo
git clone --depth 1 https://github.com/cwoodruff/dotnet-claude-code-kit

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.

agentmods badge for async-hygiene

README.md
[![agentmods](https://agentmods.dev/badge/skills/cwoodruff/dotnet-claude-code-kit/async-hygiene.svg)](https://agentmods.dev/skills/cwoodruff/dotnet-claude-code-kit/async-hygiene)
Your own site
<a href="https://agentmods.dev/skills/cwoodruff/dotnet-claude-code-kit/async-hygiene"><img src="https://agentmods.dev/badge/skills/cwoodruff/dotnet-claude-code-kit/async-hygiene.svg" alt="Measured on agentmods" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 389 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00057 $0.00389
Opus 5 $0.00028 $0.00195
Sonnet 5 $0.00011 $0.00078
Haiku 4.5 $0.00006 $0.00039

Measured 3d ago against content hash 80c2bc150c7a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

async-hygiene 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 3d 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 async-hygiene — 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.

skills/async-hygiene/SKILL.md · 22 lines

What it actually says

Async/Await Hygiene Sweep

Scan the target scope (default: whole solution) for each anti-pattern, in this order, and fix with the standard remedy:

Anti-pattern Find Fix
Sync-over-async .Result, .Wait(), .GetAwaiter().GetResult() Make the caller async and await
async void any non-event-handler Return Task
Missing CancellationToken async public methods without a token parameter Add CancellationToken cancellationToken = default and thread it through
Fire-and-forget unawaited Task-returning calls Await, or route through a background service with error handling
Task.Run in ASP.NET request path Task.Run( in Api project Remove — the request is already on a thread-pool thread
Async lambda passed to sync delegate async lambda to Action<> Change delegate type or restructure
Unnecessary async/await wrapper method whose only await is the final return Return the Task directly (unless in a using/try)
Blocking I/O in async method File.ReadAllText, Thread.Sleep inside async Use async equivalents (ReadAllTextAsync, Task.Delay)

Process: grep for each pattern → read the surrounding code (some hits are legitimate, e.g. Main, console tools) → fix true positives → dotnet build → report a table of what changed and any hits deliberately left alone with reasoning.

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. 3d ago First seen · 22 lines · 57 tokens per session scan A 80c2bc150c7a

Subscribe to this mod's changes

async-hygiene is a skill published in the GitHub repository cwoodruff/dotnet-claude-code-kit (2 stars, last pushed 1mo ago), licensed MIT. It adds 57 tokens to every session and 389 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to async-hygiene, differing in 0 lines, and is treated as a copy.

Related

Other skills, from other repositories

build-and-test

How to build and test .NET projects in the Agent Framework repository. Use this when verifying or testing changes.

microsoft/agent-framework · 26 tokens

nunit-testing

Use when writing or modifying tests in NUnit's own test projects, or when making a behavioral change to production code that needs test coverage. Covers test structure, attribute choice, helper visibility, platform guards, and which test projects are real.

nunit/nunit · 51 tokens

agents-sdk-dotnet

Use when any code imports Microsoft.Agents.Hosting.AspNetCore, Microsoft.Agents.Builder, or related Agents SDK packages, or when the user is building, configuring, or asking questions about a Microsoft 365 Agents SDK agent in C# / .NET. Trigger on questions about appsettings.json, connection configuration…

microsoft/Agents · 112 tokens

agents-sdk-dotnet-otel

Use when adding, configuring, validating, or troubleshooting OpenTelemetry observability for a Microsoft 365 Agents SDK application in C# / .NET. Trigger when the user mentions OpenTelemetry, OTel, telemetry, traces, metrics, logs, OTLP, Aspire Dashboard, Application Insights, Azure Monitor, distributed tracing…

microsoft/Agents · 86 tokens

bf-to-agents-sdk-dotnet-migration

Use when migrating a Bot Framework .NET SDK bot to Microsoft 365 Agents SDK. Triggered by projects that depend on packages: Microsoft.Bot.Builder or Microsoft.Bot.Builder.Integration.AspNet.Core that want to migrate to Agents SDK.

microsoft/Agents · 56 tokens

agents-sdk-dotnet-debugging

Use when troubleshooting an agent built with the Microsoft Agents SDK (Microsoft.Agents.Hosting.AspNetCore and related packages) in C# / .NET. Trigger on any of these symptoms: build or C# compile errors, crashes on startup, 401 or auth errors on incoming requests, the bot not responding to messages, appsettings.json…

microsoft/Agents · 136 tokens