Automatic linting and static analysis after code changes. Runs linter + type-check + shared validation scripts. MANDATORY after every code change.


Source	`.claude/skills/lint-and-validate/SKILL.md`
Owner	`testing`
Runtime	`claude-code`
Risk	medium
Phase	`on-demand`

What This Skill Does

Runs appropriate validation tools after code modifications to catch style violations, type errors, security issues, and code quality problems. MANDATORY after EVERY code change — no code is committed or reported as done without passing all checks.

For the full pipeline (build → lint → type-check → tests → coverage), use mk:verify. mk:lint-and-validate is the lint-only subset for post-edit quick checks.

When to Use

After EVERY code change. The quality loop: Write/Edit → Run audit → Analyze → Fix & Repeat.

Triggers: "lint", "format", "check", "validate", "types", "static analysis".

NOT for: full build verification (mk:verify), test coverage (mk:testing).

Core Capabilities

Commands by Ecosystem

Node.js / TypeScript:

Step	Command	Notes
Lint	`npm run lint`	Project-configured ESLint
Lint fix	`npx eslint "path" --fix`	Auto-fix fixable issues
Types	`npx tsc --noEmit`	Type check without emitting
Security	`npm audit --audit-level=high`	Skip low/moderate severity

Config files: .eslintrc, .eslintrc.json, .eslintrc.js, tsconfig.json

Python:

Step	Command	Notes
Lint	`ruff check "path" --fix`	Fast, modern, replaces flake8
Security	`bandit -r "path" -ll`	Skip low-severity
Types	`mypy "path"`	Static type analysis

Config files: pyproject.toml, setup.cfg, .ruff.toml

Shared Validation Scripts

Kit-wide scripts at .claude/scripts/:

Script	Purpose	Command
`validate.py`	General code validation	`.claude/skills/.venv/bin/python3 .claude/scripts/validate.py`
`security-scan.py`	Security pattern scanning	`.claude/skills/.venv/bin/python3 .claude/scripts/security-scan.py`

Error Recovery

Error type	Action
Lint fails	Fix style/syntax immediately
tsc fails	Correct type mismatches before continuing
No tool configured	Check for `.eslintrc`, `tsconfig.json`, `pyproject.toml` — suggest creating one
Script not found	Check `.claude/scripts/` — may not be present in all projects

Gotchas

ESLint flat config (eslint.config.mjs) and legacy .eslintrc are mutually exclusive — ESLint 9 auto-detects flat config and silently ignores .eslintrc.* files. If a project has both, flat config wins and all legacy extends rules are dropped without error, making it look like rules pass when they were never loaded.
eslint --fix on unstaged files destroys uncommitted work — --fix writes changes directly to disk. Stage with git add -p before running, or use --fix-dry-run to preview.
TypeScript ESLint parser version must match installed typescript version — a TS upgrade without bumping @typescript-eslint/parser causes Unexpected token parse errors on new syntax even though tsc accepts it fine.
extends order determines rule precedence (later wins) — ['plugin:vue/recommended', 'prettier'] works; reversing to ['prettier', 'plugin:vue/recommended'] re-enables conflicting vue formatting rules.
Prettier and ESLint format rules conflict when both run on the same file — disable all formatting rules in ESLint (eslint-config-prettier) and let Prettier own formatting.

Example Prompts

"Lint the changes I just made"
"Run type-check after refactoring the auth module"
"Validate the code before I create a PR"

Pro Tips

Run npm run lint && npx tsc --noEmit as a single command — both must pass.
If a project is missing lint config, create one before proceeding. The skill will suggest this.
The gotchas section above covers the most common traps — read it before troubleshooting lint failures.

mk:lint-and-validate

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