feat: typescript 6 update + eslint upgrade + flaky cypress test fix

eslint.config.mjs

@@ -0,0 +1,71 @@
+import js from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import next from 'eslint-config-next/core-web-vitals';
+import prettierRecommended from 'eslint-plugin-prettier/recommended';
+
+export default tseslint.config(
+  {
+    ignores: [
+      'dist/',
+      'build/',
+      'out/',
+      'node_modules/',
+      '.next/',
+      'coverage/',
+      '**/*.config.js',
+      '**/*.config.mjs',
+      'next-env.d.ts',
+    ],
+  },
+  js.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked.map((c) => ({ ...c, files: ['**/*.{ts,tsx}'] })),
+  // next[1] (next/typescript) is skipped — it re-declares @typescript-eslint,
+  // conflicting with tseslint.configs.recommended above, which we use instead
+  // for TypeScript 6 compatibility and the full recommended ruleset.
+  (({ languageOptions: _lang, ...rest }) => rest)(next[0]),
+  next[3], // core-web-vitals: promotes no-html-link-for-pages + no-sync-scripts to errors
+  {
+    files: ['**/*.{ts,tsx,js,jsx}'],
+    languageOptions: {
+      parserOptions: { projectService: true },
+    },
+    rules: {
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          vars: 'all',
+          args: 'none',
+          varsIgnorePattern: '^_',
+          caughtErrors: 'none',
+          destructuredArrayIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+        },
+      ],
+      // TODO: hooks called inside render callbacks, incorrect hook usage patterns,
+      // and missing/extra effect dependencies — to be fixed in a separate ticket.
+      'react-hooks/rules-of-hooks': 'off',
+      'react-hooks/refs': 'off',
+      'react-hooks/set-state-in-render': 'off',
+      'react-hooks/set-state-in-effect': 'off',
+      'react-hooks/immutability': 'off',
+      'react-hooks/exhaustive-deps': 'off',
+      // TypeScript handles these; disable the core JS versions.
+      'no-undef': 'off',
+      'no-unused-vars': 'off',
+      // Type-checked rules from recommendedTypeChecked that are too noisy
+      // for the current codebase — kept off to preserve parity with the
+      // previous eslint-config-standard-with-typescript baseline.
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+      '@typescript-eslint/no-unsafe-member-access': 'off',
+      '@typescript-eslint/no-unsafe-argument': 'off',
+      '@typescript-eslint/no-unsafe-call': 'off',
+      '@typescript-eslint/no-unsafe-return': 'off',
+      '@typescript-eslint/no-unsafe-enum-comparison': 'off',
+      '@typescript-eslint/no-unnecessary-type-assertion': 'off',
+      '@typescript-eslint/no-redundant-type-constituents': 'off',
+      '@typescript-eslint/require-await': 'off',
+      '@typescript-eslint/no-misused-promises': 'off',
+    },
+  },
+  prettierRecommended,
+);

package.json

@@ -55,8 +55,8 @@
     "start:dev": "next dev",
     "start:dev:mock": "NEXT_PUBLIC_API_MOCKING=enabled next dev -p 3001",
     "start:prod": "next build && next start",
-    "lint": "eslint src --ext .ts,.tsx,.js,.jsx",
-    "lint:fix": "eslint src --ext .ts,.tsx,.js,.jsx --fix",
+    "lint": "eslint src",
+    "lint:fix": "eslint src --fix",
     "test": "jest",
     "test:watch": "jest --watch",
     "test:ci": "CI=true jest",
@@ -76,19 +76,6 @@
   "resolutions": {
     "tar": "^7.5.7"
   },
-  "eslintConfig": {
-    "extends": [
-      "react-app",
-      "react-app/jest"
-    ]
-  },
-  "browserslist": {
-    "production": [
-      ">0.2%",
-      "not dead",
-      "not op_mini all"
-    ]
-  },
   "devDependencies": {
     "@react-firebase/auth": "^0.2.10",
     "@swc/core": "^1.15.8",
@@ -107,22 +94,14 @@
     "@types/react-redux": "^7.1.27",
     "@types/react-window": "^2.0.0",
     "@types/redux-saga": "^0.10.5",
-    "@typescript-eslint/eslint-plugin": "^6.7.0",
-    "@typescript-eslint/parser": "^6.7.0",
     "concurrently": "^9.2.1",
     "cypress": "^13.2.0",
     "dotenv": "^16.4.5",
     "env-cmd": "^10.1.0",
-    "eslint": "^8.49.0",
+    "eslint": "^9.35.0",
     "eslint-config-next": "^16.1.2",
     "eslint-config-prettier": "^9.0.0",
-    "eslint-config-standard-with-typescript": "^39.0.0",
-    "eslint-plugin-import": "^2.28.1",
-    "eslint-plugin-n": "^16.1.0",
     "eslint-plugin-prettier": "^5.0.0",
-    "eslint-plugin-promise": "^6.1.1",
-    "eslint-plugin-react": "^7.33.2",
-    "eslint-plugin-unused-imports": "^3.0.0",
     "firebase-tools": "^15.3.1",
     "jest": "^30.2.0",
     "jest-environment-jsdom": "^30.2.0",
@@ -132,7 +111,8 @@
     "prettier": "^3.0.3",
     "ts-loader": "^9.4.4",
     "ts-node": "^10.9.2",
-    "typescript": "^5.2.2",
+    "typescript": "6.0.3",
+    "typescript-eslint": "^8.58.1",
     "wait-on": "^7.0.1"
   },
   "engines": {

src/app/Theme.ts

@@ -15,15 +15,7 @@ declare module '@mui/material/styles' {
   interface TypeText {
     lightContrast?: string;
   }
-}
-
-declare module '@mui/material/Typography' {
-  interface TypographyPropsVariantOverrides {
-    sectionTitle: true;
-  }
-}
 
-declare module '@mui/material/styles/createMixins' {
   // Allow for custom mixins to be added
   interface Mixins {
     code: Partial<PaletteColor> & {
@@ -32,6 +24,12 @@ declare module '@mui/material/styles/createMixins' {
   }
 }
 
+declare module '@mui/material/Typography' {
+  interface TypographyPropsVariantOverrides {
+    sectionTitle: true;
+  }
+}
+
 export enum ThemeModeEnum {
   light = 'light',
   dark = 'dark',

src/global.d.ts

@@ -0,0 +1,3 @@
+// This helps Typescript understand that we can import CSS files
+// ex: maplibre-gl/dist/maplibre-gl.css
+declare module '*.css';

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "es5",
+    "target": "ES2022",
     "lib": [
       "dom",
       "dom.iterable",
@@ -14,7 +14,7 @@
     "forceConsistentCasingInFileNames": true,
     "noFallthroughCasesInSwitch": true,
     "module": "esnext",
-    "moduleResolution": "node",
+    "moduleResolution": "bundler",
     "resolveJsonModule": true,
     "isolatedModules": true,
     "noEmit": true,