Dotnet-slopwatch – detect when AI coding agents "fix" problems by cheating

// LLM anti-cheat

A .NET tool that detects LLM "reward hacking" behaviors in code changes.

Runs as a Claude Code hook or in CI/CD pipelines to catch when AI coding assistants take shortcuts instead of properly fixing issues.

When LLMs generate code, they sometimes take shortcuts that make tests pass or builds succeed without actually solving the underlying problem. These patterns include:

Disabling tests instead of fixing them ([Fact(Skip="flaky")]

)Suppressing warnings instead of addressing them (#pragma warning disable

)Swallowing exceptions with empty catch blocksAdding arbitrary delays to mask timing issues (Task.Delay(1000)

)Project-level warning suppression(<NoWarn>

,<TreatWarningsAsErrors>false</TreatWarningsAsErrors>

)Bypassing Central Package Management withVersionOverride

or inlineVersion

attributes- And more...

Slopwatch catches these patterns before they make it into your codebase.

dotnet tool install --global Slopwatch.Cmd

dotnet new tool-manifest
dotnet tool install --local Slopwatch.Cmd
dotnet tool install --global Slopwatch.Cmd

cd your-project
slopwatch init

git add .slopwatch/baseline.json
git commit -m "Add slopwatch baseline"

slopwatch analyze

The baseline approach ensures slopwatch catches new slop being introduced without flagging legacy code. Your CI/CD pipeline will fail if someone introduces new slop patterns.

slopwatch init

slopwatch init --force

This creates .slopwatch/baseline.json

containing all existing detections. Commit this file to your repository.

slopwatch analyze

slopwatch analyze -d src/

slopwatch analyze --no-baseline

When you intentionally add code that triggers slopwatch (with proper justification):

slopwatch analyze --update-baseline
slopwatch analyze

slopwatch analyze --output json
slopwatch analyze --fail-on error

slopwatch analyze --fail-on warning

If you're concerned about performance on large projects, use --stats

to see how many files are being analyzed and how long it takes:

slopwatch analyze --stats

Rule	Severity	Description
SW001	Error	Disabled tests via Skip, Ignore, or #if false
SW002	Warning	Warning suppression via pragma or SuppressMessage
SW003	Error	Empty catch blocks that swallow exceptions
SW004	Warning	Arbitrary delays in test code (Task.Delay, Thread.Sleep)
SW005	Warning	Project file slop (NoWarn, TreatWarningsAsErrors=false)
SW006	Error	CPM bypass via VersionOverride or inline Version attributes

Add slopwatch as a hook to catch slop patterns during AI-assisted coding. Add the following to your project's .claude/settings.json

:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write|Edit|MultiEdit",
        "hooks": [
          {
            "type": "command",
            "command": "slopwatch analyze -d . --hook",
            "timeout": 60000
          }
        ]
      }
    ]
  }
}

The --hook

flag enables Claude Code integration mode which:

Uses- makes hooks near-instant even on large reposgit status

to only analyze dirty files- Outputs errors to stderr in a readable format

• Suppresses all other output
• Blocks on warnings and errors
• Exits with code 2 on failure (blocking the edit)

Claude will see the formatted error message and can then fix the issue properly.

Note:Hook mode requires git. If git is unavailable, it falls back to full analysis.

- name: Install Slopwatch
  run: dotnet tool install --global Slopwatch.Cmd

- name: Run Slopwatch
  run: slopwatch analyze -d . --output json --fail-on error

Note: The baseline file (.slopwatch/baseline.json

) should be committed to your repository. Run slopwatch init

locally first.

- task: DotNetCoreCLI@2
  displayName: 'Install Slopwatch'
  inputs:
    command: 'custom'
    custom: 'tool'
    arguments: 'install --global Slopwatch.Cmd'

- script: slopwatch analyze -d . --fail-on error
  displayName: 'Run Slopwatch'

Create a .slopwatch/config.json

file to define suppressions:

{
  "suppressions": [
    {
      "ruleId": "SW002",
      "pattern": "**/Generated/**",
      "justification": "Generated code from tooling cannot be manually changed"
    },
    {
      "ruleId": "SW006",
      "pattern": "src/Legacy/**",
      "justification": "Legacy CPM migration in progress; tracked in issue #123"
    }
  ],
  "globalSuppressions": []
}

Use the -c

or --config

option to specify a custom suppression config file location:

slopwatch analyze -d . --config path/to/config.json

To exclude files or directories from analysis entirely, use --exclude

:

slopwatch analyze -d . --exclude "**/Generated/**,**/obj/**,**/bin/**"
dotnet build
dotnet test
dotnet pack

• Fork and create a feature branch
• Make changes and add tests
• Submit a pull request

Note: This project uses slopwatch on itself - your PR will be analyzed for slop patterns!

Apache 2.0 - see LICENSE for details.

Slopometry- Python equivalent for Claude CodeIncrementalist- Git diff analysis patterns

source & further reading

github.com — original article