Migrate eslint config to flat format (#3055)

Fixes #2927

Author: AndreasArvidsson

.eslintrc.json

@@ -17,7 +17,6 @@ jobs:
     runs-on: ubuntu-latest
     env:
       CURSORLESS_REPO_ROOT: ${{ github.workspace }}
-      ESLINT_USE_FLAT_CONFIG: false
 
     steps:
       - name: Checkout repository

.github/workflows/pre-commit.yml

@@ -0,0 +1,154 @@
+import eslintJs from "@eslint/js";
+import prettierConfig from "eslint-config-prettier/flat";
+import importPlugin from "eslint-plugin-import";
+import mochaPlugin from "eslint-plugin-mocha";
+import unicornPlugin from "eslint-plugin-unicorn";
+import unusedImportsPlugin from "eslint-plugin-unused-imports";
+import eslintTs, { type ConfigWithExtends } from "typescript-eslint";
+import { commonConfig } from "./packages/common/eslint.config.mts";
+import { cursorlessEngineConfig } from "./packages/cursorless-engine/eslint.config.mts";
+import { cursorlessOrgConfig } from "./packages/cursorless-org/eslint.config.mts";
+import { cursorlessVscodeConfig } from "./packages/cursorless-vscode/eslint.config.mts";
+
+const ignoresConfig: ConfigWithExtends = {
+  ignores: [
+    "**/generated/**/*",
+    "**/out/**/*",
+    "**/dist/**/*",
+    "**/build/**/*",
+    "**/vendor/**/*",
+    "**/.next/**/*",
+    "**/.docusaurus/**/*",
+    "**/eslint.config.mts",
+    "data/playground/**/*",
+  ],
+};
+
+const rootConfig: ConfigWithExtends = {
+  plugins: {
+    "unused-imports": unusedImportsPlugin,
+    import: importPlugin,
+    unicorn: unicornPlugin,
+    mocha: mochaPlugin,
+  },
+
+  languageOptions: {
+    parser: eslintTs.parser,
+    ecmaVersion: 6,
+    sourceType: "module",
+    parserOptions: {
+      project: true,
+    },
+  },
+
+  settings: {
+    "import/resolver": {
+      typescript: {
+        // Always try to resolve types under `<root>@types` directory even it doesn't contain any source code, like `@types/unist`
+        alwaysTryTypes: true,
+        project: ["tsconfig.json", "packages/*/tsconfig.json"],
+      },
+    },
+  },
+
+  rules: {
+    "import/no-relative-packages": "error",
+    "@typescript-eslint/consistent-type-imports": "error",
+    "@typescript-eslint/consistent-type-assertions": [
+      "error",
+      {
+        assertionStyle: "as",
+      },
+    ],
+    "@typescript-eslint/naming-convention": [
+      "error",
+      {
+        selector: ["objectLiteralProperty"],
+        format: ["camelCase"],
+        filter: {
+          regex: "[.]",
+          match: false,
+        },
+      },
+    ],
+    "@typescript-eslint/no-floating-promises": "error",
+    "@typescript-eslint/no-explicit-any": "off",
+    "@typescript-eslint/no-inferrable-types": "off",
+    "@typescript-eslint/no-non-null-assertion": "off",
+    "unused-imports/no-unused-imports": "error",
+    "@typescript-eslint/no-unused-vars": [
+      "error",
+      {
+        argsIgnorePattern: "^_",
+        varsIgnorePattern: "^_",
+        caughtErrorsIgnorePattern: "^_",
+        ignoreRestSiblings: true,
+      },
+    ],
+    curly: "error",
+    eqeqeq: [
+      "error",
+      "always",
+      {
+        null: "never",
+      },
+    ],
+    "no-constant-condition": [
+      "error",
+      {
+        checkLoops: false,
+      },
+    ],
+    "no-restricted-syntax": [
+      "error",
+      "MemberExpression[object.property.name='constructor'][property.name='name']",
+    ],
+    "no-throw-literal": "error",
+    semi: "off",
+    "unicorn/prefer-module": "error",
+    "mocha/no-pending-tests": "error",
+    "mocha/no-exclusive-tests": "error",
+  },
+};
+
+const tsxConfig: ConfigWithExtends = {
+  files: ["**/*.tsx"],
+  rules: {
+    "@typescript-eslint/naming-convention": [
+      "error",
+      {
+        selector: ["function"],
+        format: ["PascalCase", "camelCase"],
+      },
+    ],
+  },
+};
+
+const disabledTypeCheckConfig: ConfigWithExtends = {
+  files: [
+    "**/jest.config.ts",
+    "**/docusaurus.config.mts",
+    "**/mdx-components.tsx",
+    "typings/**",
+    "**/*.js",
+    "**/*.mjs",
+  ],
+
+  extends: [eslintTs.configs.disableTypeChecked],
+};
+
+export default eslintTs.config(
+  ignoresConfig,
+  eslintJs.configs.recommended,
+  // We want to enable this in the long run. For now there are a lot of errors that needs to be handled.
+  // eslintTs.configs.recommendedTypeChecked,
+  eslintTs.configs.recommended,
+  prettierConfig,
+  rootConfig,
+  tsxConfig,
+  disabledTypeCheckConfig,
+  commonConfig,
+  cursorlessEngineConfig,
+  cursorlessVscodeConfig,
+  cursorlessOrgConfig,
+);

eslint.config.mts

@@ -18,7 +18,7 @@
     "fix:syncpack": "pnpm syncpack fix-mismatches",
     "init-vscode-sandbox": "pnpm --filter=@cursorless/cursorless-vscode init-launch-sandbox",
     "lint:meta": "pnpm run meta-updater:base --test",
-    "lint:ts": "cross-env ESLINT_USE_FLAT_CONFIG=false eslint packages --ext ts,tsx,mts",
+    "lint:ts": "eslint packages --ext ts,tsx,mts",
     "lint": "pnpm run lint:meta && syncpack list-mismatches && pnpm run lint:ts",
     "meta-updater:base": "pnpm --filter=@cursorless/meta-updater build && meta-updater",
     "preinstall": "npx only-allow pnpm",
@@ -31,23 +31,23 @@
     "watch:tsc": "tsc --build --watch"
   },
   "devDependencies": {
+    "@eslint/eslintrc": "^3.3.1",
+    "@eslint/js": "^9.31.0",
     "@pnpm/meta-updater": "^2.0.6",
     "@types/node": "^24.0.15",
-    "@typescript-eslint/eslint-plugin": "^8.38.0",
-    "@typescript-eslint/parser": "^8.38.0",
-    "cross-env": "^7.0.3",
     "esbuild": "^0.25.8",
     "eslint": "^9.31.0",
     "eslint-config-prettier": "^10.1.8",
     "eslint-import-resolver-typescript": "^4.4.4",
     "eslint-plugin-import": "^2.32.0",
-    "eslint-plugin-mocha": "^10.5.0",
-    "eslint-plugin-unicorn": "^56.0.1",
+    "eslint-plugin-mocha": "^11.1.0",
+    "eslint-plugin-unicorn": "^60.0.0",
     "eslint-plugin-unused-imports": "^4.1.4",
     "prettier": "~3.3.3",
     "prettier-plugin-tailwindcss": "^0.6.14",
     "syncpack": "^13.0.4",
-    "typescript": "^5.8.3"
+    "typescript": "^5.8.3",
+    "typescript-eslint": "^8.38.0"
   },
   "pnpm": {
     "patchedDependencies": {

package.json

@@ -1,5 +1,4 @@
 // Generated using webpack-cli https://github.com/webpack/webpack-cli
-/*eslint-env node*/
 
 import {
   cheatsheetBodyClasses,

packages/cheatsheet-local/src/webpack.config.ts

@@ -0,0 +1,37 @@
+import type { ConfigArray } from "typescript-eslint";
+
+export const commonConfig: ConfigArray = [
+  {
+    files: ["packages/common/**/*.ts"],
+
+    ignores: ["**/*.test.ts"],
+
+    rules: {
+      "import/no-nodejs-modules": "error",
+    },
+  },
+
+  {
+    files: ["packages/common/src/types/command/**/*.ts"],
+
+    rules: {
+      "@typescript-eslint/no-restricted-imports": [
+        "error",
+        {
+          patterns: [
+            {
+              group: ["@cursorless/*", "../*"],
+              message: "API types shouldn't have any dependencies",
+            },
+          ],
+          paths: [
+            {
+              name: "@*",
+              message: "API types shouldn't have any dependencies",
+            },
+          ],
+        },
+      ],
+    },
+  },
+];

packages/common/.eslintrc.json

@@ -1,8 +1,10 @@
 #!/usr/bin/env node
 // @ts-check
-/*eslint-env node*/
+/* global process, console */
+
 // This script runs a TypeScript file using Node.js by first bundling it with
 // esbuild.
+
 import { spawn } from "cross-spawn";
 import { build } from "esbuild";
 import { existsSync, mkdirSync, rmdirSync } from "node:fs";