ln-741-linter-configurator

SKILL.md

Paths: File paths (references/, ../ln-*) are relative to this skill directory.

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
1d:[