Drop eslint-config-airbnb-base and cherry-pick rules

Remove the unmaintained eslint-config-airbnb-base dependency (last
updated Nov 2021, no flat config support) along with its FlatCompat
shim infrastructure.

Replace with js.configs.recommended as the base config and explicitly
cherry-pick ~40 high-value safety and style rules from airbnb-base
that aren't already covered by other configs.

Remove 27 rule disables that only existed to suppress airbnb opinions,
and 5 dead TypeScript rule disables for rules no longer in the config.

Fix 4 real bugs caught by the newly added no-constant-binary-expression
rule where template literals were always truthy, making fallback values
unreachable.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: loganrosen

demo/src/stubs/recorder.ts

@@ -15,7 +15,6 @@ import type { MockHomeAssistant } from "../../../src/fake_data/provide_hass";
 const generateMeanStatistics = (
   start: Date,
   end: Date,
-  // eslint-disable-next-line default-param-last
   period: "5minute" | "hour" | "day" | "month" = "hour",
   maxDiff: number
 ): StatisticValue[] => {
@@ -49,7 +48,6 @@ const generateMeanStatistics = (
 const generateSumStatistics = (
   start: Date,
   end: Date,
-  // eslint-disable-next-line default-param-last
   period: "5minute" | "hour" | "day" | "month" = "hour",
   initValue: number,
   maxDiff: number
@@ -86,7 +84,6 @@ const generateSumStatistics = (
 const generateCurvedStatistics = (
   start: Date,
   end: Date,
-  // eslint-disable-next-line default-param-last
   _period: "5minute" | "hour" | "day" | "month" = "hour",
   initValue: number,
   maxDiff: number,

eslint.config.mjs

@@ -2,10 +2,7 @@
 
 import unusedImports from "eslint-plugin-unused-imports";
 import globals from "globals";
-import path from "node:path";
-import { fileURLToPath } from "node:url";
 import js from "@eslint/js";
-import { FlatCompat } from "@eslint/eslintrc";
 import tseslint from "typescript-eslint";
 import eslintConfigPrettier from "eslint-config-prettier";
 import { configs as litConfigs } from "eslint-plugin-lit";
@@ -14,35 +11,8 @@ import { configs as a11yConfigs } from "eslint-plugin-lit-a11y";
 import html from "@html-eslint/eslint-plugin";
 import importX from "eslint-plugin-import-x";
 
-const _filename = fileURLToPath(import.meta.url);
-const _dirname = path.dirname(_filename);
-const compat = new FlatCompat({
-  baseDirectory: _dirname,
-  recommendedConfig: js.configs.recommended,
-  allConfig: js.configs.all,
-});
-
-// Load airbnb-base via FlatCompat for non-import rules only.
-// eslint-plugin-import is incompatible with ESLint 10 (uses removed APIs),
-// so we strip its plugin/rules/settings and use eslint-plugin-import-x instead.
-const airbnbConfigs = compat.extends("airbnb-base").map((config) => {
-  const { plugins = {}, rules = {}, settings = {}, ...rest } = config;
-  return {
-    ...rest,
-    plugins: Object.fromEntries(
-      Object.entries(plugins).filter(([key]) => key !== "import")
-    ),
-    rules: Object.fromEntries(
-      Object.entries(rules).filter(([key]) => !key.startsWith("import/"))
-    ),
-    settings: Object.fromEntries(
-      Object.entries(settings).filter(([key]) => !key.startsWith("import/"))
-    ),
-  };
-});
-
 export default tseslint.config(
-  ...airbnbConfigs,
+  js.configs.recommended,
   eslintConfigPrettier,
   litConfigs["flat/all"],
   tseslint.configs.recommended,
@@ -86,35 +56,61 @@ export default tseslint.config(
     },
 
     rules: {
-      "class-methods-use-this": "off",
-      "new-cap": "off",
-      "prefer-template": "off",
-      "object-shorthand": "off",
-      "func-names": "off",
-      "no-underscore-dangle": "off",
-      strict: "off",
-      "no-plusplus": "off",
+      // Cherry-picked safety rules (previously provided by airbnb-base)
+      "array-callback-return": ["error", { allowImplicit: true }],
+      "block-scoped-var": "error",
+      "consistent-return": "error",
+      curly: ["error", "multi-line"],
+      "default-case-last": "error",
+      eqeqeq: ["error", "always", { null: "ignore" }],
+      "guard-for-in": "error",
+      "no-await-in-loop": "error",
+      "no-caller": "error",
+      "no-constructor-return": "error",
+      "no-eval": "error",
+      "no-extend-native": "error",
+      "no-implied-eval": "error",
+      "no-iterator": "error",
+      "no-new-func": "error",
+      "no-new-wrappers": "error",
+      "no-octal-escape": "error",
+      "no-promise-executor-return": "error",
+      "no-return-assign": ["error", "always"],
+      "no-script-url": "error",
+      "no-self-compare": "error",
+      "no-sequences": "error",
+      "no-template-curly-in-string": "error",
+      "no-unreachable-loop": "error",
+
+      // Cherry-picked style rules (previously provided by airbnb-base)
+      "no-else-return": ["error", { allowElseIf: false }],
+      "no-lonely-if": "error",
+      "no-unneeded-ternary": ["error", { defaultAssignment: false }],
+      "no-useless-computed-key": "error",
+      "no-useless-concat": "error",
+      "no-useless-rename": "error",
+      "no-useless-return": "error",
+      "one-var": ["error", "never"],
+      "operator-assignment": ["error", "always"],
+      "prefer-arrow-callback": "error",
+      "prefer-exponentiation-operator": "error",
+      "prefer-object-spread": "error",
+      "prefer-regex-literals": ["error", { disallowRedundantWrapping: true }],
+      "symbol-description": "error",
+      yoda: "error",
+
+      // TODO: Enable once violations are fixed (43 instances as of 2026-04)
+      // "no-useless-assignment": "error",
+      "no-useless-assignment": "off",
+
+      // Project rules
       "no-bitwise": "error",
-      "comma-dangle": "off",
-      "vars-on-top": "off",
-      "no-continue": "off",
-      "no-param-reassign": "off",
-      "no-multi-assign": "off",
       "no-console": "error",
-      radix: "off",
-      "no-alert": "off",
-      "no-nested-ternary": "off",
-      "prefer-destructuring": "off",
       "no-restricted-globals": [2, "event"],
-      "prefer-promise-reject-errors": "off",
       "no-restricted-syntax": ["error", "LabeledStatement", "WithStatement"],
-      "object-curly-newline": "off",
-      "default-case": "off",
       "wc/no-self-class": "off",
-      "no-shadow": "off",
-      "no-use-before-define": "off",
 
-      // import-x rules (migrated from eslint-plugin-import / airbnb-base)
+      // import-x rules
       "import-x/named": "off",
       "import-x/prefer-default-export": "off",
       "import-x/no-default-export": "off",
@@ -146,13 +142,9 @@ export default tseslint.config(
       "import-x/no-relative-packages": "error",
 
       // TypeScript rules
-      "@typescript-eslint/camelcase": "off",
       "@typescript-eslint/ban-ts-comment": "off",
-      "@typescript-eslint/no-use-before-define": "off",
       "@typescript-eslint/no-non-null-assertion": "off",
       "@typescript-eslint/no-explicit-any": "off",
-      "@typescript-eslint/explicit-function-return-type": "off",
-      "@typescript-eslint/explicit-module-boundary-types": "off",
       "@typescript-eslint/no-shadow": ["error"],
 
       "@typescript-eslint/naming-convention": [
@@ -216,7 +208,6 @@ export default tseslint.config(
       "lit-a11y/role-has-required-aria-attrs": "error",
       "@typescript-eslint/consistent-type-imports": "error",
       "@typescript-eslint/no-import-type-side-effects": "error",
-      camelcase: "off",
       "@typescript-eslint/no-dynamic-delete": "off",
       "@typescript-eslint/no-empty-object-type": [
         "error",

gallery/src/pages/components/ha-input.ts

@@ -27,7 +27,6 @@ export class DemoHaInput extends LitElement {
   constructor() {
     super();
     // Provides internationalizationContext for ha-input-copy, ha-input-multi and ha-input-search
-    // eslint-disable-next-line no-new
     new ContextProvider(this, {
       context: internationalizationContext,
       initialValue: {

package.json

@@ -136,7 +136,6 @@
     "@babel/plugin-transform-runtime": "7.29.0",
     "@babel/preset-env": "7.29.2",
     "@bundle-stats/plugin-webpack-filter": "4.22.1",
-    "@eslint/eslintrc": "3.3.5",
     "@eslint/js": "10.0.1",
     "@html-eslint/eslint-plugin": "0.59.0",
     "@lokalise/node-api": "15.7.1",
@@ -169,10 +168,8 @@
     "browserslist-useragent-regexp": "4.1.4",
     "del": "8.0.1",
     "eslint": "10.2.0",
-    "eslint-config-airbnb-base": "15.0.0",
     "eslint-config-prettier": "10.1.8",
     "eslint-import-resolver-webpack": "0.13.11",
-    "eslint-plugin-import": "2.32.0",
     "eslint-plugin-import-x": "4.16.2",
     "eslint-plugin-lit": "2.2.1",
     "eslint-plugin-lit-a11y": "5.1.1",

src/common/dom/ancestors-with-property.ts

@@ -21,8 +21,9 @@ export const closestWithProperty = (
     own
       ? Object.prototype.hasOwnProperty.call(element, property)
       : element && property in element
-  )
+  ) {
     return element;
+  }
   return closestWithProperty(element, property, own);
 };
 

src/common/util/select-unit.ts

@@ -19,7 +19,6 @@ const SECS_PER_HOUR = SECS_PER_MIN * 60;
 // Adapted from https://github.com/formatjs/formatjs/blob/186cef62f980ec66252ee232f438a42d0b51b9f9/packages/intl-utils/src/diff.ts
 export function selectUnit(
   from: Date | number,
-  // eslint-disable-next-line default-param-last
   to: Date | number = Date.now(),
   locale: FrontendLocaleData,
   thresholds: Partial<Thresholds> = {}

src/components/chart/state-history-chart-line.ts

@@ -128,8 +128,9 @@ export class StateHistoryChartLine extends LitElement {
       if (
         dataset.tooltip?.show === false ||
         this._hiddenStats.has(dataset.id as string)
-      )
+      ) {
         return;
+      }
       const param = params.find(
         (p: Record<string, any>) => p.seriesIndex === index
       );

src/components/ha-ansi-to-html.ts

@@ -177,7 +177,6 @@ export class HaAnsiToHtml extends LitElement {
       lineDiv.appendChild(span);
     };
 
-    /* eslint-disable no-cond-assign */
     let match;
 
     while ((match = re.exec(line)) !== null) {

src/components/ha-attribute-value.ts

@@ -26,7 +26,7 @@ class HaAttributeValue extends LitElement {
         try {
           // If invalid URL, exception will be raised
           const url = new URL(attributeValue);
-          if (url.protocol === "http:" || url.protocol === "https:")
+          if (url.protocol === "http:" || url.protocol === "https:") {
             return html`
               <a
                 target="_blank"
@@ -36,6 +36,7 @@ class HaAttributeValue extends LitElement {
                 ${attributeValue}
               </a>
             `;
+          }
         } catch {
           // Nothing to do here
         }

src/components/ha-code-editor.ts

@@ -370,11 +370,12 @@ export class HaCodeEditor extends ReactiveElement {
   }
 
   private _fullscreenLabel(): string {
-    if (this._isFullscreen)
+    if (this._isFullscreen) {
       return (
         this.hass?.localize("ui.components.yaml-editor.exit_fullscreen") ||
         "Exit fullscreen"
       );
+    }
     return (
       this.hass?.localize("ui.components.yaml-editor.enter_fullscreen") ||
       "Enter fullscreen"