Stylecop Analyzers

StyleCop Analyzers

Trigger On

• the repo wants StyleCop.Analyzers
• naming, layout, or documentation style needs stronger enforcement
• the team needs stylecop.json guidance

Value

• produce a concrete project delta: code, docs, config, tests, CI, or review artifact
• reduce ambiguity through explicit planning, verification, and final validation skills
• leave reusable project context so future tasks are faster and safer

Do Not Use For

• repos that intentionally rely only on SDK analyzers
• repos where StyleCop overlaps too heavily with an existing style package and no consolidation is planned

Inputs

• the nearest AGENTS.md
• current .editorconfig
• any existing stylecop.json

Quick Start

1. Read the nearest AGENTS.md and confirm scope and constraints. 2. Run this skill's Workflow through the Ralph Loop until outcomes are acceptable. 3. Return the Required Result Format with concrete artifacts and verification evidence.

Workflow

1. Add StyleCop.Analyzers only if the repo wants its opinionated style rules. 2. Keep severity in the root .editorconfig. 3. Use stylecop.json only for StyleCop-specific behavioral options. 4. Prefer one checked-in stylecop.json per repo unless a project genuinely needs its own behavior. 5. Avoid rule duplication with SDK analyzers or other analyzer packs when possible.

Bootstrap When Missing

If StyleCop.Analyzers is not configured yet:

1. Detect current state:

• rg -n "StyleCop\\.Analyzers|stylecop\\.json" -g '*.csproj' -g 'stylecop.json' .

2. Add package to the intended scope:

• dotnet add PROJECT.csproj package StyleCop.Analyzers

3. Keep severity in root .editorconfig and use stylecop.json only for StyleCop-specific behavior. 4. Prevent overlap with existing analyzer packs by defining ownership. 5. Run dotnet build SOLUTION_OR_PROJECT and return status: configured or status: improved. 6. If the repo intentionally uses SDK analyzers only, return status: not_applicable.

Deliver

• explicit StyleCop package setup
• repo-owned StyleCop rule configuration
• clear split between root .editorconfig and stylecop.json

Validate

• StyleCop severity is versioned in repo config
• stylecop.json is used only where it adds value

Ralph Loop

Use the Ralph Loop for every task, including docs, architecture, testing, and tooling work.

1. Plan first (mandatory):

• analyze current state
• define target outcome, constraints, and risks
• write a detailed execution plan
• list final validation skills to run at the end, with order and reason

2. Execute one planned step and produce a concrete delta. 3. Review the result and capture findings with actionable next fixes. 4. Apply fixes in small batches and rerun the relevant checks or review steps. 5. Update the plan after each iteration. 6. Repeat until outcomes are acceptable or only explicit exceptions remain. 7. If a dependency is missing, bootstrap it or return status: not_applicable with explicit reason and fallback path.

Required Result Format

• status: complete | clean | improved | configured | not_applicable | blocked
• plan: concise plan and current iteration step
• actions_taken: concrete changes made
• validation_skills: final skills run, or skipped with reasons
• verification: commands, checks, or review evidence summary
• remaining: top unresolved items or none

For setup-only requests with no execution, return status: configured and exact next commands.

Load References

• references/stylecop-analyzers.md
• references/rules.md
• references/config.md

Example Requests

• "Add StyleCop.Analyzers to this solution."
• "Configure StyleCop without losing .editorconfig ownership."

StyleCop Analyzers Configuration Reference

Configuration Files

StyleCop Analyzers uses two configuration sources:

stylecop.json Schema

Always include the schema reference for IDE support:

{
  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
  "settings": {
    // Configuration sections go here
  }
}

Configuration Sections

documentationRules

Controls XML documentation behavior.

{
  "settings": {
    "documentationRules": {
      "companyName": "Your Company",
      "copyrightText": "Copyright (c) {companyName}. All rights reserved.",
      "headerDecoration": "-----------------------------------------------------------------------",
      "documentExposedElements": true,
      "documentInternalElements": false,
      "documentPrivateElements": false,
      "documentInterfaces": true,
      "documentPrivateFields": false,
      "fileNamingConvention": "stylecop",
      "xmlHeader": false,
      "variables": {
        "customVariable": "value"
      },
      "excludeFromPunctuationCheck": ["seealso", "typeparam"]
    }
  }
}

orderingRules

Controls using directive and element ordering.

{
  "settings": {
    "orderingRules": {
      "usingDirectivesPlacement": "outsideNamespace",
      "systemUsingDirectivesFirst": true,
      "blankLinesBetweenUsingGroups": "require",
      "elementOrder": [
        "kind",
        "accessibility",
        "constant",
        "static",
        "readonly"
      ]
    }
  }
}

namingRules

Controls naming convention enforcement.

{
  "settings": {
    "namingRules": {
      "allowCommonHungarianPrefixes": true,
      "allowedHungarianPrefixes": ["ui", "db"],
      "allowedNamespaceComponents": ["eBay", "iPhone"],
      "includeInferredTupleElementNames": false,
      "tupleElementNameCasing": "camelCase"
    }
  }
}

layoutRules

Controls file and code layout.

{
  "settings": {
    "layoutRules": {
      "newlineAtEndOfFile": "require",
      "allowConsecutiveUsings": true,
      "allowDoWhileOnClosingBrace": false
    }
  }
}

readabilityRules

Controls readability enforcement.

{
  "settings": {
    "readabilityRules": {
      "allowBuiltInTypeAliases": false
    }
  }
}

indentation (deprecated)

Note: Indentation settings were deprecated. Use .editorconfig for indentation.

{
  "settings": {
    "indentation": {
      "indentationSize": 4,
      "tabSize": 4,
      "useTabs": false
    }
  }
}

Complete stylecop.json Examples

Minimal Configuration

{
  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
  "settings": {
    "orderingRules": {
      "usingDirectivesPlacement": "outsideNamespace"
    },
    "layoutRules": {
      "newlineAtEndOfFile": "require"
    }
  }
}

Open Source Project

{
  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
  "settings": {
    "documentationRules": {
      "companyName": "Project Contributors",
      "copyrightText": "Licensed under the MIT License. See LICENSE in the project root.",
      "documentExposedElements": true,
      "documentInternalElements": false,
      "xmlHeader": false
    },
    "orderingRules": {
      "usingDirectivesPlacement": "outsideNamespace",
      "systemUsingDirectivesFirst": true,
      "blankLinesBetweenUsingGroups": "require"
    },
    "layoutRules": {
      "newlineAtEndOfFile": "require"
    }
  }
}

Enterprise Project

{
  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
  "settings": {
    "documentationRules": {
      "companyName": "Contoso Corporation",
      "copyrightText": "Copyright (c) {companyName}. All rights reserved.\nLicensed under the Contoso Enterprise License.",
      "headerDecoration": "-----------------------------------------------------------------------",
      "documentExposedElements": true,
      "documentInternalElements": true,
      "documentInterfaces": true,
      "xmlHeader": true
    },
    "orderingRules": {
      "usingDirectivesPlacement": "outsideNamespace",
      "systemUsingDirectivesFirst": true,
      "blankLinesBetweenUsingGroups": "require",
      "elementOrder": [
        "kind",
        "accessibility",
        "constant",
        "static",
        "readonly"
      ]
    },
    "namingRules": {
      "allowCommonHungarianPrefixes": false
    },
    "layoutRules": {
      "newlineAtEndOfFile": "require"
    }
  }
}

Project Integration

Add to Project File

Link stylecop.json as an additional file:

<ItemGroup>
  <AdditionalFiles Include="$(MSBuildThisFileDirectory)stylecop.json" Link="stylecop.json" />
</ItemGroup>

Add to Directory.Build.props

For solution-wide configuration:

<Project>
  <ItemGroup>
    <AdditionalFiles Include="$(MSBuildThisFileDirectory)stylecop.json" Link="stylecop.json" />
  </ItemGroup>
</Project>

Multiple Configuration Files

For project-specific overrides:

<!-- In a specific project -->
<ItemGroup>
  <AdditionalFiles Remove="$(MSBuildThisFileDirectory)stylecop.json" />
  <AdditionalFiles Include="stylecop.project.json" Link="stylecop.json" />
</ItemGroup>

Configuration Precedence

1. Project-specific stylecop.json 2. Directory-level stylecop.json via Directory.Build.props 3. Root stylecop.json 4. Default StyleCop Analyzers settings

Rule severity always comes from .editorconfig, not stylecop.json.

Validation

Validate configuration with schema:

# Check JSON syntax
python3 -c "import json; json.load(open('stylecop.json'))"

The schema URL provides IDE validation in VS Code, Visual Studio, and JetBrains Rider.

Sources

• StyleCop Analyzers Configuration
• stylecop.json Schema

StyleCop Analyzers Rules Reference

Rule Categories

StyleCop Analyzers organizes rules into these categories:

Commonly Adjusted Rules

Spacing Rules (SA1xxx)

Readability Rules (SA12xx)

Ordering Rules (SA13xx)

Maintainability Rules (SA14xx)

Layout Rules (SA15xx)

Documentation Rules (SA16xx)

Naming Rules (SA17xx)

Alternative Rules (SXxxxx)

.editorconfig Configuration Examples

Minimal Enforcement

[*.cs]
# Disable verbose documentation requirements
dotnet_diagnostic.SA1600.severity = none
dotnet_diagnostic.SA1601.severity = none
dotnet_diagnostic.SA1602.severity = none
dotnet_diagnostic.SA1633.severity = none

# Disable this-prefix requirement
dotnet_diagnostic.SA1101.severity = none

# Allow underscore prefix for fields
dotnet_diagnostic.SA1309.severity = none

Strict Enforcement

[*.cs]
# Enable most rules as warnings
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.DocumentationRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.LayoutRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.MaintainabilityRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.NamingRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.OrderingRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.ReadabilityRules.severity = warning
dotnet_analyzer_diagnostic.category-StyleCop.CSharp.SpacingRules.severity = warning

# Exceptions
dotnet_diagnostic.SA1101.severity = none
dotnet_diagnostic.SA1633.severity = none

Common Rule Combinations

For teams using underscore-prefixed private fields:

[*.cs]
dotnet_diagnostic.SA1309.severity = none
dotnet_diagnostic.SX1309.severity = warning

For teams not requiring file headers:

[*.cs]
dotnet_diagnostic.SA1633.severity = none
dotnet_diagnostic.SA1634.severity = none
dotnet_diagnostic.SA1635.severity = none
dotnet_diagnostic.SA1636.severity = none
dotnet_diagnostic.SA1637.severity = none
dotnet_diagnostic.SA1638.severity = none
dotnet_diagnostic.SA1640.severity = none
dotnet_diagnostic.SA1641.severity = none

Rule Conflicts

With SDK Analyzers

Some StyleCop rules overlap with SDK analyzers:

• IDE0003/IDE0009 vs SA1101: this. qualification
• IDE0055 vs SA1000-SA1028: Spacing rules
• IDE0161 vs SA1402: File-scoped namespaces

Resolution: Disable the less-preferred analyzer in .editorconfig.

With Roslynator

• RCS1018 vs SA1400: Access modifiers
• RCS1090 vs SA1101: this. prefix
• Multiple formatting overlaps

Resolution: Choose one analyzer pack as the authority for each rule category.

Sources

• StyleCop Analyzers Rules
• Rule Documentation Index

StyleCop.Analyzers

Open/Free Status

• open source
• free to use

Install

dotnet add package StyleCop.Analyzers

Verify First

Before adding the package, check whether the repo already references it:

rg -n "StyleCop\\.Analyzers|stylecop\\.json" -g '*.csproj' -g 'stylecop.json' .

Ownership Model

• keep severity and enable/disable policy in the repo-root .editorconfig
• keep stylecop.json only for StyleCop behavior that .editorconfig does not express well
• do not let stylecop.json become a second rule-severity system

Common Usage

• keep rule severity in the root .editorconfig
• use stylecop.json for StyleCop-specific behavior where needed
• run through normal build:

dotnet build MySolution.sln -warnaserror

Root .editorconfig Example

root = true

[*.cs]
dotnet_diagnostic.SA1200.severity = warning
dotnet_diagnostic.SA1208.severity = warning
dotnet_diagnostic.SA1516.severity = warning
dotnet_diagnostic.SA1600.severity = none

stylecop.json Example

{
  "$schema": "https://raw.githubusercontent.com/DotNetAnalyzers/StyleCopAnalyzers/master/StyleCop.Analyzers/StyleCop.Analyzers/Settings/stylecop.schema.json",
  "settings": {
    "documentationRules": {
      "companyName": "Managed Code",
      "documentExposedElements": true,
      "documentInternalElements": false
    },
    "orderingRules": {
      "usingDirectivesPlacement": "outsideNamespace",
      "blankLinesBetweenUsingGroups": "require"
    },
    "layoutRules": {
      "newlineAtEndOfFile": "require"
    }
  }
}

What stylecop.json Is Good For

• documentation behavior
• using placement
• ordering behavior
• file-header settings
• indentation behavior that must match StyleCop expectations

What Should Stay In .editorconfig

• rule severity
• whether a specific SAxxxx rule is warning, error, suggestion, or none
• cross-analyzer ownership with SDK analyzers, Roslynator, or Meziantou

CI Fit

• use build warnings or errors as the gate
• do not let stylecop.json replace .editorconfig as severity owner
• keep stylecop.json in source control and schema-backed when possible

When Not To Use

• when the repo intentionally wants a lighter analyzer surface
• when a bundled coding-standard package already supersedes StyleCop

Sources

• StyleCopAnalyzers
• StyleCop Analyzers configuration