disallow-stylelint-duplicate-rule-option-values

Disallow duplicate scalar literals in array-valued Stylelint secondary rule options.

Targeted pattern scope

This rule targets Stylelint config modules such as stylelint.config.ts, stylelint.config.mjs, and .stylelintrc.js.

It focuses on top-level exported config objects, including configs wrapped in defineConfig(...).

What this rule reports

Reports duplicate scalar literals in array-valued properties inside secondary option objects.

Why this rule exists

Duplicate option values add noise and can obscure actual rule intent during config review.

❌ Incorrect

export default {
    rules: {
        "selector-class-pattern": [
            "^[a-z]+$",
            {
                resolveNestedSelectors: [":global", ":global", ":host"],
            },
        ],
    },
};

✅ Correct

export default {
    rules: {
        "selector-class-pattern": [
            "^[a-z]+$",
            {
                resolveNestedSelectors: [":global", ":host"],
            },
        ],
    },
};

Behavior and migration notes

This rule auto-fixes by keeping the first occurrence of each duplicate scalar literal value.

ESLint flat config example

import stylelint2 from "eslint-plugin-stylelint-2";

export default [stylelint2.configs.configuration];

When not to use it

Do not use this rule if your stylelint secondary option arrays intentionally include duplicate scalar values for generated-tool compatibility.

Package documentation

Stylelint package documentation:

Rule catalog ID: R032

Further reading

• Stylelint secondary options