@lilith/eslint-config-base

Base ESLint configuration with TypeScript, Prettier, and strict Python-like formatting.

Philosophy

Strict, consistent formatting inspired by Python's black/ruff:

• All formatting rules are autofix-enabled
• Prettier handles code style
• ESLint handles code quality
• One way to do things (consistent patterns)

Features

• TypeScript Strict: Full type-checking with @typescript-eslint
• Prettier Integration: Seamless code formatting
• Import Organization: Python-like strict ordering and grouping
• Blank Line Rules: PEP 8-inspired whitespace
• Code Quality: Best practices enforcement

Installation

pnpm add -D @lilith/eslint-config-base

Peer Dependencies

pnpm add -D \
  eslint \
  typescript \
  @typescript-eslint/parser \
  @typescript-eslint/eslint-plugin \
  eslint-plugin-import \
  eslint-plugin-prettier \
  eslint-config-prettier \
  prettier

Usage

// .eslintrc.cjs
module.exports = {
  extends: ['@lilith/eslint-config-base'],
  parserOptions: {
    project: './tsconfig.json',
  },
};

Or use it directly:

// .eslintrc.cjs
module.exports = require('@lilith/eslint-config-base');

Rule Categories

TypeScript Strict Rules

Rule	Severity	Description
no-unused-vars	error	No unused variables (allows _ prefix)
no-explicit-any	warn	Avoid any type
no-floating-promises	error	Must handle promises
no-misused-promises	error	Correct promise usage
await-thenable	error	Only await thenables
consistent-type-imports	error	Use import type for types
consistent-type-definitions	error	Use interface over type
prefer-optional-chain	error	Use ?. instead of && chains

Import Organization

Enforces strict import ordering:

// 1. Built-in modules (node:fs, node:path)
import fs from 'node:fs';

// 2. External dependencies
import express from 'express';

// 3. Internal modules
import { config } from '@/config';

// 4. Parent imports
import { utils } from '../utils';

// 5. Sibling imports
import { helper } from './helper';

// 6. Type imports (always last)
import type { Config } from './types';

Blank Line Rules (PEP 8-like)

import { something } from 'somewhere';
// <blank line after imports>

const config = {};
// <blank line after const/let/var blocks>

function doSomething() {
  // ...
}
// <blank line before/after functions>

class MyClass {
  // ...
}
// <blank line before/after classes>

if (condition) {
  // ...
}
// <blank line after block statements>

return result;
// <blank line before return>

Code Quality Rules

Rule	Description
prefer-const	Use const when possible
no-var	Never use var
eqeqeq	Always use ===
curly	Always use braces
no-else-return	No else after return
prefer-template	Use template literals
object-shorthand	Use shorthand properties
arrow-body-style	Concise arrow functions

File Length (SOLID/SRP Enforcement)

This config includes @lilith/eslint-plugin-file-length to enforce architectural discipline:

Threshold	Severity	Action
400 lines	Warning	Review for SRP violations
600 lines	Error	Must refactor before proceeding

Why file length matters:

Large files typically violate the Single Responsibility Principle (SRP). A file with 500+ lines usually has multiple reasons to change, making it:

• Harder to test
• Harder to maintain
• A source of merge conflicts
• A sign of architectural drift

How to resolve warnings/errors:

1. Identify responsibilities - What are the different reasons this file might change?
2. Extract by concern - Split into focused modules (auth, validation, data access, etc.)
3. Apply DRY - Extract shared patterns to reusable modules
4. Don't game metrics - Splitting into part1.ts/part2.ts defeats the purpose

For detailed resolution strategies and examples, see the @lilith/eslint-plugin-file-length README.

Exemptions (configured by default):

• *.seed.ts, *.data.ts - Data files
• *.generated.ts - Generated code
• *.config.ts - Configuration
• **/migrations/*.ts - Database migrations

Ignored Patterns

The following are ignored by default:

• node_modules/
• dist/
• build/
• *.config.ts / *.config.js
• *.d.ts
• *.test.ts / *.spec.ts
• **/__tests__/**

Customization

Override rules in your config:

module.exports = {
  extends: ['@lilith/eslint-config-base'],
  rules: {
    // Allow console in development
    'no-console': process.env.NODE_ENV === 'production' ? 'error' : 'off',

    // Customize unused vars pattern
    '@typescript-eslint/no-unused-vars': ['error', {
      argsIgnorePattern: '^_',
      varsIgnorePattern: '^_|^React$',
    }],
  },
};

Related Packages

• @lilith/eslint-plugin-file-length - File length enforcement (included)
• @lilith/eslint-config-react - React-specific rules
• @lilith/eslint-config-nestjs - NestJS-specific rules
• @lilith/configs - Unified configuration package

License

MIT

Final full test 1767646525