EditorConfig Configuration Skill

This skill provides .editorconfig template and validation logic for maintaining consistent coding styles across editors and IDEs.

Purpose

Manage .editorconfig configuration to:

• Enforce consistent character encoding and line endings
• Define language-specific indentation rules
• Preserve trailing whitespace where needed (Markdown)
• Ensure monorepo consistency with single root configuration
• Cover all common file types in MetaSaver projects

Usage

This skill is invoked by the editorconfig-agent when:

• Creating new .editorconfig files
• Auditing existing EditorConfig configurations
• Validating EditorConfig files against standards

Template

The standard EditorConfig template is located at:

templates/.editorconfig.template

The 4 EditorConfig Standards

Rule 1: Root Declaration

File must start with root declaration:

root = true

This stops EditorConfig from searching parent directories, ensuring the monorepo has a single source of truth.

Rule 2: Universal Settings with Default Indentation

Must include [*] section with these six settings:

[*]
charset = utf-8
end_of_line = lf
insert_final_newline = true
trim_trailing_whitespace = true
indent_style = space
indent_size = 2

These settings apply to all files unless overridden by language-specific rules. The default 2-space indentation is inherited by most file types.

Rule 3: Language-Specific Sections

Must include sections for all common file types:

Core language sections (required):

# TypeScript, JavaScript, JSX, TSX
[*.{ts,tsx,js,jsx,mjs,cjs}]
indent_size = 2
max_line_length = 100

# JSON files
[*.json]
indent_size = 2

# YAML files
[*.{yml,yaml}]
indent_size = 2

# Markdown files
[*.md]
trim_trailing_whitespace = false
max_line_length = off

# Python (if used in tooling)
[*.py]
indent_style = space
indent_size = 4

Extended sections (recommended):

# Shell scripts
[*.sh]
indent_size = 2

# Makefiles
[Makefile]
indent_style = tab

# Package.json (specific formatting)
[package.json]
indent_size = 2

# Lock files (should not be edited)
[{package-lock.json,pnpm-lock.yaml,yarn.lock}]
indent_size = 2
insert_final_newline = false

# SQL files
[*.sql]
indent_size = 2

# Docker files
[{Dockerfile,*.dockerfile}]
indent_size = 2

# Prisma schema files
[*.prisma]
indent_size = 2

Rule 4: Root Location Only

In monorepos, .editorconfig must exist ONLY at repository root:

• Place at monorepo root (alongside pnpm-workspace.yaml)
• Individual packages must only reference the root .editorconfig file
• Single configuration ensures consistency across all packages

Validation

Validation steps:

1. Check file exists at repository root
2. Verify root declaration is present
3. Check universal settings section [*] with all 6 settings (including indent defaults)
4. Verify core language-specific sections exist (JS/TS, JSON, YAML, Markdown, Python)
5. Scan for package-level .editorconfig files (monorepo only)
6. Report violations

Validation Logic

// Rule 1: Root declaration
if (!content.includes("root = true")) {
  errors.push("Rule 1: Missing 'root = true' declaration");
}

// Rule 2: Universal settings (check all 6)
[
  "[*]",
  "charset = utf-8",
  "end_of_line = lf",
  "insert_final_newline = true",
  "trim_trailing_whitespace = true",
  "indent_style = space",
  "indent_size = 2",
].forEach((setting) => {
  if (!content.includes(setting)) errors.push(`Rule 2: Missing ${setting}`);
});

// Rule 3: Core language sections
if (!/\[\*\.\{[^}]*ts[^}]*\}\]/.test(content)) {
  errors.push("Rule 3: Missing JS/TS indentation rules");
}
if (!/\[\*\.json\]/.test(content)) {
  errors.push("Rule 3: Missing JSON section");
}
if (!/\[\*\.\{[^}]*yml[^}]*\}\]/.test(content)) {
  errors.push("Rule 3: Missing YAML section");
}
if (!/\[\*\.md\]/.test(content)) {
  errors.push("Rule 3: Missing Markdown section");
}
if (!/\[\*\.py\]/.test(content)) {
  errors.push("Rule 3: Missing Python section");
}

// Rule 4: Package-level configs (monorepo only)
const packageConfigs = glob("packages/**/.editorconfig");
if (packageConfigs.length > 0) {
  errors.push(
    `Rule 4: Remove package-level configs: ${packageConfigs.join(", ")}`,
  );
}

Exception Declaration

Repos may declare exceptions in package.json:

{
  "metasaver": {
    "exceptions": {
      "editorconfig-config": {
        "type": "custom-language-rules",
        "reason": "Requires 4-space indentation for legacy YAML files"
      }
    }
  }
}

Best Practices

1. Place .editorconfig at repository root (monorepo or standalone)
2. Use template as starting point
3. Preserve Markdown trailing whitespace (for double-space line breaks)
4. Keep extended sections for comprehensive coverage
5. Re-audit after making changes

Integration

This skill integrates with:

• Repository type provided via scope parameter. If not provided, use /skill scope-check
• /skill audit-workflow - Bi-directional comparison workflow
• /skill remediation-options - Conform/Update/Ignore choices
• prettier-agent - Coordination with Prettier formatting rules
• eslint-agent - Coordination with ESLint style rules