Node Lint

node-lint

Sets up lint + format so they catch real defects instead of fighting each other. The failures this skill fixes: models write legacy .eslintrc configs that current ESLint majors no longer load, mix two formatters, claim Biome replaces type checking, and reset intentional rule customizations during migrations.

When NOT to use

• Next.js apps → nextjs-quality owns eslint-config-next and RSC rules.
• Type checking / tsconfig → node-typescript (Biome's type-aware rules are not a tsc replacement — never claim otherwise).
• Test setup → node-testing; CI workflow authoring → node-ci.

Workflow

1. Detect before choosing. Package manager (lockfile), existing configs (.eslintrc*, eslint.config.*, biome.json*, .prettierrc*), framework, and plugin needs (a11y, imports, framework-specific). Plugin needs decide the tool: read the decision table in references/lint-playbook.md.
   • Biome — one tool for lint+format, fastest path for TS libraries/apps without exotic plugin needs.
   • ESLint (flat config only — modern majors do not load eslintrc) + Prettier — when the plugin ecosystem is required.
   • Never two formatters; never ESLint stylistic rules alongside a formatter.
2. Write the explicit config from the playbook's starter blocks — full config, no reliance on version-varying defaults. Wire package.json scripts (lint, format, lint:fix) with --max-warnings=0 for CI use.
3. Migrations (when an old setup exists): follow the playbook's path — official flat-config migrator or biome migrate eslint. Diff the effective rule set; preserve intentional customizations; run on the whole codebase and triage new findings before deleting the old config.
4. Verify:

   python3 "${CLAUDE_SKILL_DIR}/scripts/check_lint_setup.py"
   

   plus a clean run of the chosen tool over the repo (npx biome check . or npx eslint . --max-warnings=0).
5. Report the tool choice rationale, rules deliberately disabled, and where CI should call the scripts (route the workflow wiring to node-ci).

Output spec

One linter + one formatter, explicit committed config, scripts wired, zero errors/warnings on the current codebase (or a documented triage list), no leftover legacy config files, editor settings noted.

Gotchas

• Flat config resolves relative to each linted file's directory in current ESLint majors — monorepo packages can carry their own config layers.
• biome migrate eslint maps what it can; rules without Biome equivalents are dropped silently — always diff and list them.
• Version-gate everything: tool majors move fast; the playbook marks claims that must be re-verified against official docs at use time.
• A lint pass that only silences rules is a failure — tune by fixing signal.

Files

• references/lint-playbook.md — decision table, explicit starter configs, migration paths, tuning discipline.
• scripts/check_lint_setup.py — deterministic sanity checks (single formatter, no legacy+flat config coexistence, scripts wired); non-zero exit on violations.