Paths: File paths (shared/ , references/ , ../ln-* ) are relative to skills repo root. If not found at CWD, locate this SKILL.md directory and go up one level for repo root. If shared/ is missing, fetch files via WebFetch from https://raw.githubusercontent.com/levnikolaevich/claude-code-skills/master/skills/{path} .

ln-741-linter-configurator

Type: L3 Worker Category: 7XX Project Bootstrap

Configures code linting, formatting, and type checking tools for TypeScript, Python, and .NET projects.

Purpose & Scope

Does:

• Detects which linter stack to configure based on project type

• Checks for existing linter configurations

• Generates appropriate config files from templates

• Installs required dependencies (always latest versions, no pinning)

• Generates unified lint script (scripts/lint.sh )

• Verifies all linters run without errors

Does NOT:

• Configure pre-commit hooks (separate worker)

• Set up test infrastructure (separate worker)

• Modify source code

Supported Stacks

Technology Linter Type Checker Formatter Config Files

TypeScript ESLint 9+ (flat config) TypeScript (tsc) Prettier eslint.config.ts , .prettierrc

.NET Roslyn Analyzers Roslyn dotnet format .editorconfig , Directory.Build.props

Python Ruff mypy Ruff (built-in) ruff.toml , mypy.toml (or pyproject.toml )

Phase 1: Check Existing Configuration

Before generating configs, check what already exists.

Files to Check:

Stack Config Files Glob Pattern

TypeScript ESLint config eslint.config.* , .eslintrc*

TypeScript Prettier config .prettierrc* , prettier.config.*

.NET Editor config .editorconfig

.NET Build props Directory.Build.props

Python Ruff config ruff.toml , pyproject.toml

Python mypy config mypy.toml , mypy.ini , pyproject.toml [tool.mypy]

Decision Logic:

• If no config exists: CREATE from template

• If config exists but incomplete (fewer rules/tools than template): EXTEND to match template

• If config matches template: SKIP (inform user)

Completeness Check (Python):

Aspect Check Template Standard

Ruff rules Count select entries 23+ categories (see ruff_template.toml )

Ruff per-file-ignores Tests section exists tests/**/*.py with S101,S105,S106,T201

Ruff advanced mccabe, flake8-bugbear, isort All present

MyPy strict = true

Enabled

Advanced tools import-linter, deptry, vulture in dev deps All installed

Lint script scripts/lint.sh with 7 checks All 7 active

.editorconfig File exists Present

Phase 2: Generate Configuration

Use templates from references/ folder. Customize placeholders based on project.

TypeScript:

• Copy eslint_template.ts to project root as eslint.config.ts

• Copy prettier_template.json as .prettierrc

• Add scripts to package.json :

• "lint": "eslint ."

• "lint:fix": "eslint . --fix"

• "format": "prettier --write ."

• "format:check": "prettier --check ."

• "typecheck": "tsc --noEmit"

• "lint:all": "npm run typecheck && npm run lint && npm run format:check"

• For React projects: uncomment React sections in template

.NET:

• Copy editorconfig_template.ini as .editorconfig

• Copy directory_build_props_template.xml as Directory.Build.props

• Ensure analyzers are included (SDK 5+ includes them by default)

Python:

• Copy ruff_template.toml as ruff.toml

• OR merge into existing pyproject.toml under [tool.ruff]

• Copy mypy_template.toml as mypy.toml

• OR merge into existing pyproject.toml under [tool.mypy]

• Update known-first-party in isort config to match project package name

• Update files in mypy config to match project source directories

• Generate advanced tool configs in pyproject.toml :

• [tool.importlinter] from importlinter_template.toml -- adapt root_packages and contracts to project layer structure

• [tool.vulture] from vulture_template.toml -- adapt paths to project source directory

• [tool.deptry] from deptry_template.toml -- adapt extend_exclude

• Generate .editorconfig from editorconfig_template.ini -- adapt max_line_length to match ruff line-length

Phase 3: Install Dependencies

Install required packages. Always install latest versions — no version pinning.

TypeScript:

npm install -D eslint @eslint/js typescript-eslint eslint-config-prettier prettier eslint-plugin-unicorn jiti

For React projects, also install: npm install -D eslint-plugin-react eslint-plugin-react-hooks

Note on jiti: Required for eslint.config.ts on Node.js < 22.10. On Node.js 22.10+ TypeScript configs are supported natively.

.NET:

• Analyzers included in SDK 5+ — no separate install needed

Python:

uv add --dev ruff mypy import-linter deptry vulture pip-audit

OR without uv:

pip install ruff mypy import-linter deptry vulture pip-audit

Phase 4: Generate Lint Script

Generate scripts/lint.sh from lint_script_template.sh with ALL checks for the detected stack.

• Copy lint_script_template.sh to scripts/lint.sh

• Uncomment ALL check lines matching detected stack -- both basic AND advanced tools:

Stack Checks TOTAL

Python ruff check, ruff format, mypy, lint-imports, deptry, vulture, pip-audit 7

TypeScript typecheck, eslint, prettier, knip, depcruise 5

.NET dotnet build, dotnet format 2

• Set TOTAL to match active checks count

• Uncomment matching auto-fix commands in --fix block

• Make executable: chmod +x scripts/lint.sh

• For TypeScript: ensure "lint:all" script exists in package.json

Phase 5: Verify Setup

After configuration, verify everything works.

TypeScript:

npx tsc --noEmit npx eslint . npx prettier --check .

.NET:

dotnet format --verify-no-changes

Python:

ruff check . ruff format --check . mypy

Unified verification:

bash scripts/lint.sh

Expected: Exit code 0 for all checks.

On Failure: Check error output, adjust config, re-verify.

Phase 6: Fix Lint Errors

After generating all configs and installing tools, run bash scripts/lint.sh --all to see all violations.

• Run bash scripts/lint.sh --fix to auto-fix what ruff can

• Fix remaining errors manually (file by file)

• For C901 (complexity) on functions that cannot be refactored now: add # noqa: C901

• For deptry false positives: add [tool.deptry.per_rule_ignores] entries

• Repeat until bash scripts/lint.sh passes with 0 failures

Critical Rules

RULE 1: Always include eslint-config-prettier (last in config) when using ESLint + Prettier together.

RULE 2: Use ESLint flat config format (eslint.config.ts ), NOT legacy .eslintrc .

RULE 3: Ruff replaces Black, isort, flake8, and many other Python tools. Do NOT install them separately.

RULE 4: Never disable strict TypeScript rules without documented reason.

RULE 5: Always run mypy alongside Ruff for Python projects. Ruff handles style/bugs, mypy handles type safety.

RULE 6: Use recommendedTypeChecked as ESLint default, not just recommended . Downgrade individual rules if needed.

RULE 7: Never pin dependency versions in install commands -- always install latest.

RULE 8: Advanced static analysis tools (import-linter, deptry, vulture, pip-audit) are MANDATORY for Python projects, not optional.

Monitor (2.1.98+): When lint/typecheck verification commands expected >30s, use Monitor . Fallback: Bash(run_in_background=true) .

Definition of Done

• Appropriate config files created for detected stack

• Dependencies installed (latest versions)

• scripts/lint.sh generated with correct checks for stack

• Lint command runs without errors on project source

• Format command runs without errors

• Type checker runs without errors (mypy for Python, tsc for TypeScript)

• No ESLint/Prettier conflicts (eslint-config-prettier installed)

• Advanced tools installed and configured (import-linter, deptry, vulture, pip-audit)

• scripts/lint.sh runs ALL checks (7 for Python) with exit code 0

• .editorconfig created with settings matching ruff config

• User informed of available lint/format commands

Reference Files

File Purpose

eslint_template.ts ESLint flat config template (TypeScript)

prettier_template.json Prettier config template

ruff_template.toml Python Ruff config template

mypy_template.toml Python mypy config template

lint_script_template.sh Unified lint script template

editorconfig_template.ini .NET editorconfig template

directory_build_props_template.xml .NET analyzers template

importlinter_template.toml Python import-linter config template

vulture_template.toml Python vulture config template

deptry_template.toml Python deptry config template

linter_guide.md Detailed configuration guide

Error Handling

Error Cause Resolution

ESLint/Prettier conflict Missing eslint-config-prettier Install and add as last config

ESLint projectService error Config file not in tsconfig Add to allowDefaultProject list

ESLint .ts config fails Missing jiti npm install -D jiti

TypeScript parse errors Parser version mismatch Align typescript-eslint with TS version

mypy missing stubs Third-party library without types Add [[mypy.overrides]] with ignore_missing_imports

mypy strict too strict Hundreds of errors on first run Start with relaxed config, enable strict gradually

Ruff not found Not installed pip install ruff or uv add ruff

dotnet format fails Missing SDK Install .NET SDK

Version: 4.0.0 Last Updated: 2026-03-18