Unify linting: replace Stylelint and markdownlint with ESLint (#4148)

We were running three separate lint tools (ESLint, Stylelint,
markdownlint-cli2) and a separate Prettier step. This PR consolidates
everything: `@eslint/css` and `@eslint/markdown` bring CSS and Markdown
linting into ESLint, so one tool now covers JS, CSS, and Markdown. The
Prettier step got merged into the lint scripts too, so there's now just
`test:lint` to check things and `lint:fix` to fix them.

Outcome: fewer tools to maintain, simpler/fewer scripts, fewer config
files.

As a side effect, the dependabot alerts
https://github.com/MagicMirrorOrg/MagicMirror/security/dependabot/140
and
https://github.com/MagicMirrorOrg/MagicMirror/security/dependabot/141
are resolved, as we no longer use the vulnerable `fast-uri` package
(which was a dependency of `stylelint`).

.github/CONTRIBUTING.md

@@ -8,25 +8,10 @@ We hold our code to standard, and these standards are documented below.
 
 We use [prettier](https://prettier.io/) for automatic formatting a lot all our files. The configuration is in our `prettier.config.mjs` file.
 
-To run prettier, use `node --run lint:prettier`.
+And we use [ESLint](https://eslint.org) to lint our JavaScript, Markdown, and CSS files. The configuration is in our `eslint.config.mjs` file.
 
-### JavaScript: Run ESLint
-
-We use [ESLint](https://eslint.org) to lint our JavaScript files. The configuration is in our `eslint.config.mjs` file.
-
-To run ESLint, use `node --run lint:js`.
-
-### CSS: Run StyleLint
-
-We use [StyleLint](https://stylelint.io) to lint our CSS. The configuration is in our `stylelint.config.mjs` file.
-
-To run StyleLint, use `node --run lint:css`.
-
-### Markdown: Run markdownlint
-
-We use [markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2) to lint our markdown files. The configuration is in our `.markdownlint.json` file.
-
-To run markdownlint, use `node --run lint:markdown`.
+To check for formatting and linting errors, use `node --run test:lint`
+To fix formatting and linting errors, use `node --run lint:fix`.
 
 ## Testing
 
@@ -43,6 +28,7 @@ The `package.json` scripts expose finer-grained test commands:
 - `test:watch` – keep Vitest in watch mode for fast local feedback
 - `test:ui` – open the Vitest UI dashboard (needs OS file-watch support enabled)
 - `test:calendar` – run the legacy calendar debug helper
-- `test:css`, `test:markdown`, `test:prettier`, `test:spelling`, `test:js` – lint-only scripts that enforce formatting, spelling, markdown style, and ESLint.
+- `test:lint` – run linter and formatter checks
+- `test:spelling` – run the spell checker
 
 You can invoke any script with `node --run <script>` (or `npm run <script>`). Individual files can still be targeted directly, e.g. `npx vitest run tests/e2e/env_spec.js`.

.github/PULL_REQUEST_TEMPLATE.md

@@ -10,7 +10,7 @@ Hello and thank you for wanting to contribute to the MagicMirror² project!
 > - What does the pull request accomplish? Use a list if needed.
 > - If it includes major visual changes please add screenshots.
 >
-> 3. Please run `node --run lint:prettier` before submitting so that
+> 3. Please run `node --run lint:fix` before submitting so that
 >    style issues are fixed.
 
 **Note**: Sometimes the development moves very fast. It is highly

.github/workflows/automated-tests.yaml

@@ -33,10 +33,7 @@ jobs:
           node --run install-mm:dev
       - name: "Run linter tests"
         run: |
-          node --run test:prettier
-          node --run test:js
-          node --run test:css
-          node --run test:markdown
+          node --run test:lint
   test:
     runs-on: ubuntu-24.04
     timeout-minutes: 30

.markdownlint.json

@@ -1,6 +0,0 @@
-{
-	"line_length": false,
-	"no-duplicate-heading": false,
-	"no-inline-html": false,
-	"no-trailing-punctuation": false
-}

cspell.config.json

@@ -290,7 +290,6 @@
 		"sthuber",
 		"Stieber",
 		"strinner",
-		"stylelintrc",
 		"sunaction",
 		"suncalc",
 		"suntimes",

eslint.config.mjs

@@ -1,8 +1,10 @@
 import {defineConfig, globalIgnores} from "eslint/config";
+import css from "@eslint/css";
 import globals from "globals";
 import {flatConfigs as importX} from "eslint-plugin-import-x";
 import js from "@eslint/js";
 import jsdocPlugin from "eslint-plugin-jsdoc";
+import markdown from "@eslint/markdown";
 import {configs as packageJsonConfigs} from "eslint-plugin-package-json";
 import playwright from "eslint-plugin-playwright";
 import stylistic from "@stylistic/eslint-plugin";
@@ -10,6 +12,25 @@ import vitest from "@vitest/eslint-plugin";
 
 export default defineConfig([
 	globalIgnores(["config/**", "modules/**/*", "js/positions.js", "tests/configs/config_variables.js"]),
+	{
+		files: ["**/*.css"],
+		language: "css/css",
+		plugins: {css},
+		extends: ["css/recommended"],
+		rules: {
+			"css/no-invalid-properties": ["error", {allowUnknownVariables: true}],
+			"css/use-baseline": "off"
+		}
+	},
+	{
+		files: ["**/*.md"],
+		plugins: {markdown},
+		language: "markdown/gfm",
+		extends: ["markdown/recommended"],
+		rules: {
+			"markdown/no-missing-label-refs": "off"
+		}
+	},
 	{
 		files: ["**/*.js"],
 		languageOptions: {

package.json

@@ -51,10 +51,7 @@
 		"config:check": "node js/check_config.js",
 		"install-mm": "npm install --no-audit --no-fund --no-update-notifier --only=prod --omit=dev",
 		"install-mm:dev": "npm install --no-audit --no-fund --no-update-notifier && npx playwright install chromium",
-		"lint:css": "stylelint 'css/**/*.css' 'defaultmodules/**/*.css' --fix",
-		"lint:js": "eslint --fix",
-		"lint:markdown": "markdownlint-cli2 . --fix",
-		"lint:prettier": "prettier . --write",
+		"lint:fix": "eslint --fix && prettier . --write",
 		"prepare": "[ -f node_modules/.bin/husky ] && husky || echo no husky installed.",
 		"server": "node ./serveronly",
 		"server:watch": "node ./serveronly/watcher.js",
@@ -69,21 +66,19 @@
 		"test": "vitest run",
 		"test:calendar": "node ./defaultmodules/calendar/debug.js",
 		"test:coverage": "vitest run --coverage",
-		"test:css": "stylelint 'css/**/*.css' 'defaultmodules/**/*.css'",
 		"test:e2e": "vitest run tests/e2e",
 		"test:electron": "vitest run tests/electron",
-		"test:js": "eslint",
-		"test:markdown": "markdownlint-cli2 .",
-		"test:prettier": "prettier . --check",
+		"test:lint": "eslint && prettier . --check",
 		"test:spelling": "cspell . --gitignore",
 		"test:ui": "vitest --ui",
 		"test:unit": "vitest run tests/unit",
 		"test:watch": "vitest"
 	},
 	"lint-staged": {
-		"*": "prettier --ignore-unknown --write",
-		"*.js": "eslint --fix",
-		"*.css": "stylelint --fix"
+		"*": [
+			"eslint --fix",
+			"prettier --write --ignore-unknown"
+		]
 	},
 	"dependencies": {
 		"@fontsource/roboto": "^5.2.10",
@@ -110,7 +105,9 @@
 		"weathericons": "^2.1.0"
 	},
 	"devDependencies": {
+		"@eslint/css": "^1.2.0",
 		"@eslint/js": "^10.0.1",
+		"@eslint/markdown": "^8.0.1",
 		"@stylistic/eslint-plugin": "^5.10.0",
 		"@vitest/coverage-v8": "^4.1.5",
 		"@vitest/eslint-plugin": "^1.6.16",
@@ -124,14 +121,10 @@
 		"husky": "^9.1.7",
 		"jsdom": "^29.1.1",
 		"lint-staged": "^17.0.2",
-		"markdownlint-cli2": "^0.22.1",
 		"msw": "^2.14.3",
 		"playwright": "^1.59.1",
 		"prettier": "^3.8.3",
 		"prettier-plugin-jinja-template": "^2.2.0",
-		"stylelint": "^17.11.0",
-		"stylelint-config-standard": "^40.0.0",
-		"stylelint-prettier": "^5.0.3",
 		"vitest": "^4.1.5"
 	},
 	"optionalDependencies": {

prettier.config.mjs

@@ -1,12 +1,6 @@
 const config = {
 	plugins: ["prettier-plugin-jinja-template"],
 	overrides: [
-		{
-			files: "*.md",
-			options: {
-				parser: "markdown"
-			}
-		},
 		{
 			files: ["*.njk"],
 			options: {

stylelint.config.mjs

@@ -1,7 +0,0 @@
-const config = {
-	extends: ["stylelint-config-standard", "stylelint-prettier/recommended"],
-	root: true,
-	rules: {}
-};
-
-export default config;