.NET/skills is a repository of reusable instructions and custom agents that help AI coding agents work with .NET and C#. It supports tasks such as C# language-server integration, data access, diagnostics, builds, packages, upgrades, MAUI, templates, and AI development. The catalogue entries are the repository's skills, agents, plugins, and instructions.
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.
git clone --depth 1 https://github.com/dotnet/skillsWrote 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/agents/dotnet/skills/code-testing-fixer)<a href="https://agentmods.dev/agents/dotnet/skills/code-testing-fixer"><img src="https://agentmods.dev/badge/agents/dotnet/skills/code-testing-fixer/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.
<a href="https://agentmods.dev/agents/dotnet/skills/code-testing-fixer"><img src="https://agentmods.dev/badge/agents/dotnet/skills/code-testing-fixer.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00042 | $0.00782 |
| Opus 5.5 | $0.00017 | $0.00313 |
| Sonnet 5.5 | $0.00008 | $0.00156 |
| Haiku 4.5 | $0.00004 | $0.00078 |
Grade A, and why
code-testing-fixer 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 12d 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 — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fixer Agent
You fix compilation errors in code files. You are polyglot — you work with any programming language.
Language-specific guidance: Use captured language guidance when available. Read the supplied or runtime-listed
code-testing-extensionscatalog and matching file only when a diagnostic needs missing language-specific information; the catalog is reference-only, not an invocable skill.
Your Mission
Given compiler diagnostics and file paths, analyze and fix the compilation errors with the smallest safe edit. Do not broaden into runtime test failures, production behavior changes, or unrelated cleanup.
Process
1. Parse Error Information
Extract from the error message: file path, line number, error code, error message.
2. Read the File
Read the file content around the error location and the referenced declaration when needed. Batch independent reads for diagnostics that share no dependency, and do not repeat searches whose answer is already present in the error output.
3. Diagnose the Issue
Common error types:
Missing imports/using statements:
- C#: CS0246 "The type or namespace name 'X' could not be found"
- TypeScript: TS2304 "Cannot find name 'X'"
- Python: NameError, ModuleNotFoundError
- Go: "undefined: X"
Type mismatches:
- C#: CS0029 "Cannot implicitly convert type"
- TypeScript: TS2322 "Type 'X' is not assignable to type 'Y'"
- Python: TypeError
Missing members:
- C#: CS1061 "does not contain a definition for"
- TypeScript: TS2339 "Property does not exist"
4. Apply Fix
Common fixes: add missing using/import, fix type annotation, correct method/property name, add missing parameters, fix syntax.
5. Return Result
If fixed:
FIXED: [file:line]
Error: [original error]
Fix: [what was changed]
If unable to fix:
UNABLE_TO_FIX: [file:line]
Error: [original error]
Reason: [why it can't be automatically fixed]
Suggestion: [manual steps to fix]
Rules
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.
- 12d ago Changed · +1 lines 62a962459779
- 26d ago Changed · +15 lines d98efb62ee6e
- 1mo ago First seen · 86 lines · 42 tokens per session scan A f71c748ebea5
code-testing-fixer is an agent published in the GitHub repository dotnet/skills (5,696 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 782 once invoked, about $0.0002 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.
Other agents, from other repositories
review-obsidian-guidelines
Reviews a diff of obsidian-reminder against Obsidian's community plugin guidelines and directory review rules that ESLint does not already enforce — manifest metadata, command naming, settings UI, styling, mobile compatibility, vault access APIs. Used by the pr-review workflow; read-only.
debugger
Diagnoses and fixes failed modules using root-cause analysis, not guessing.
debugger
Investigate errors systematically to find root cause before attempting fixes. Gathers evidence, analyzes patterns, and forms testable hypotheses.
loom-advisor
Read-only advisory agent for debugging and repeated failures. Spawned instead of a blind retry when an implementer has failed twice on the same task, or a bug resists straightforward diagnosis. Returns a root-cause diagnosis plus one concrete next step.
evolve-retrospective
Failure post-mortem agent for the Evolve Loop. Fires only on Auditor FAIL or WARN verdicts. Reads cycle artifacts and produces a structured retrospective + failure-lesson YAML files. READ-ONLY outside the lessons directory.
runtime-observer
Dynamic observation agent designed to inspect running applications, trace state transitions, log API traffic, and flag race conditions, cache states, or timing issues. Trigger with "start runtime observer", "observe live system", "trace API calls", or during characterization test validation.