diff --git a/.eslintignore b/.eslintignore
deleted file mode 100644
index 5b93972..0000000
--- a/.eslintignore
+++ /dev/null
@@ -1,60 +0,0 @@
-# Logs
-logs
-*.log
-
-# Runtime data
-pids
-*.pid
-*.seed
-
-# Directory for instrumented libs generated by jscoverage/JSCover
-lib-cov
-
-# Coverage directory used by tools like istanbul
-coverage
-
-# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
-.grunt
-
-# node-waf configuration
-.lock-wscript
-
-# Compiled binary addons (http://nodejs.org/api/addons.html)
-build/Release
-.eslintcache
-
-# Dependency directory
-# https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git
-node_modules
-app/node_modules
-
-# OSX
-.DS_Store
-
-# Build outputs
-release
-out
-dist
-dll
-
-# Old webpack build artifacts
-app/*.main.prod.js
-app/main.prod.js
-app/main.prod.js.map
-app/renderer.prod.js
-app/renderer.prod.js.map
-app/style.css
-app/style.css.map
-main.js
-main.js.map
-
-.idea
-npm-debug.log.*
-__snapshots__
-
-# Package.json
-package.json
-.travis.yml
-*.css.d.ts
-*.sass.d.ts
-*.scss.d.ts
diff --git a/.eslintrc.js b/.eslintrc.js
deleted file mode 100644
index 21fc4ab..0000000
--- a/.eslintrc.js
+++ /dev/null
@@ -1,52 +0,0 @@
-module.exports = {
-  extends: 'erb/typescript',
-  rules: {
-    '@typescript-eslint/ban-ts-comment': 'warn',
-    '@typescript-eslint/no-use-before-define': 'off',
-    '@typescript-eslint/naming-convention': 'off',
-    'consistent-return': 'warn',
-    'dot-notation': 'off',
-    'import/no-extraneous-dependencies': 'off',
-    'import/prefer-default-export': 'off',
-    'import/no-cycle': 'warn',
-    'jsx-a11y/anchor-is-valid': 'warn',
-    'jsx-a11y/click-events-have-key-events': 'warn',
-    'lines-between-class-members': 'off',
-    'max-classes-per-file': 'off',
-    'no-param-reassign': 'off',
-    'no-plusplus': 'off',
-    'no-restricted-syntax': 'off',
-    'prefer-destructuring': 'warn',
-    'promise/no-return-wrap': 'warn',
-    'react/destructuring-assignment': 'off',
-    'react/jsx-curly-newline': 'off',
-    'react/jsx-one-expression-per-line': 'off',
-    'react/jsx-props-no-spreading': 'off',
-    'react/jsx-wrap-multilines': 'off',
-    'react/no-access-state-in-setstate': 'warn',
-    'react/no-array-index-key': 'off',
-    'react/no-did-update-set-state': 'warn',
-    'react/no-will-update-set-state': 'warn',
-    'react/prop-types': 'off',
-    'react/static-property-placement': 'off',
-  },
-  parserOptions: {
-    ecmaVersion: 2020,
-    sourceType: 'module',
-    project: './tsconfig.json',
-    tsconfigRootDir: __dirname,
-    createDefaultProgram: true,
-  },
-  settings: {
-    'import/resolver': {
-      // See https://github.com/benmosher/eslint-plugin-import/issues/1396#issuecomment-575727774 for line below
-      node: {},
-      webpack: {
-        config: require.resolve('./configs/webpack.config.eslint.js'),
-      },
-    },
-    'import/parsers': {
-      '@typescript-eslint/parser': ['.ts', '.tsx'],
-    },
-  },
-};
diff --git a/eslint.config.mjs b/eslint.config.mjs
new file mode 100644
index 0000000..116779a
--- /dev/null
+++ b/eslint.config.mjs
@@ -0,0 +1,174 @@
+import js from '@eslint/js';
+import tsPlugin from '@typescript-eslint/eslint-plugin';
+import tsParser from '@typescript-eslint/parser';
+import reactPlugin from 'eslint-plugin-react';
+import reactHooksPlugin from 'eslint-plugin-react-hooks';
+import importPlugin from 'eslint-plugin-import';
+import jsxA11yPlugin from 'eslint-plugin-jsx-a11y';
+import prettierPlugin from 'eslint-plugin-prettier';
+import prettierConfig from 'eslint-config-prettier';
+import globals from 'globals';
+import { fileURLToPath } from 'url';
+import { dirname } from 'path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+export default [
+  // --- Global ignores (replaces .eslintignore) ---
+  {
+    ignores: [
+      'node_modules/**',
+      'out/**',
+      'release/**',
+      'dist/**',
+      'coverage/**',
+      'src/renderer/utils/pyodide/src/**',
+      '**/*.css.d.ts',
+      '**/*.scss.d.ts',
+    ],
+  },
+
+  // --- Base JS recommended rules ---
+  js.configs.recommended,
+
+  // --- TypeScript-eslint flat/recommended (array of 3 config objects) ---
+  // Sets up @typescript-eslint parser + plugin globally and TS-specific rules.
+  ...tsPlugin.configs['flat/recommended'],
+
+  // --- React flat recommended ---
+  {
+    ...reactPlugin.configs.flat.recommended,
+    settings: { react: { version: 'detect' } },
+  },
+
+  // --- React hooks recommended (flat config) ---
+  reactHooksPlugin.configs['recommended-latest'],
+
+  // --- TypeScript + React source files ---
+  {
+    files: ['src/**/*.{ts,tsx}', 'internals/**/*.ts'],
+    languageOptions: {
+      parser: tsParser,
+      parserOptions: {
+        ecmaVersion: 2020,
+        sourceType: 'module',
+        tsconfigRootDir: __dirname,
+      },
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+        ...globals.es2020,
+      },
+    },
+    plugins: {
+      import: importPlugin,
+      'jsx-a11y': jsxA11yPlugin,
+      prettier: prettierPlugin,
+    },
+    settings: {
+      react: { version: 'detect' },
+      'import/parsers': {
+        '@typescript-eslint/parser': ['.ts', '.tsx'],
+      },
+      'import/resolver': { node: {} },
+    },
+    rules: {
+      // jsx-a11y recommended rules
+      ...jsxA11yPlugin.configs.recommended.rules,
+
+      // Prettier formatting
+      ...prettierConfig.rules,
+      'prettier/prettier': 'warn',
+
+      // Downgrade from error → warn for gradual adoption
+      '@typescript-eslint/ban-ts-comment': 'warn',
+      '@typescript-eslint/no-explicit-any': 'warn',
+      '@typescript-eslint/no-unused-vars': 'warn',
+
+      // Disabled from old config
+      '@typescript-eslint/no-use-before-define': 'off',
+      '@typescript-eslint/naming-convention': 'off',
+      'consistent-return': 'warn',
+      'dot-notation': 'off',
+      'import/no-extraneous-dependencies': 'off',
+      'import/prefer-default-export': 'off',
+      'import/no-cycle': 'warn',
+      'jsx-a11y/anchor-is-valid': 'warn',
+      'jsx-a11y/click-events-have-key-events': 'warn',
+      'jsx-a11y/no-autofocus': 'warn',
+      'react/no-unknown-property': 'warn',
+      'lines-between-class-members': 'off',
+      'max-classes-per-file': 'off',
+      'no-param-reassign': 'off',
+      'no-plusplus': 'off',
+      'no-restricted-syntax': 'off',
+      'prefer-destructuring': 'warn',
+      'react/destructuring-assignment': 'off',
+      'react/jsx-curly-newline': 'off',
+      'react/jsx-one-expression-per-line': 'off',
+      'react/jsx-props-no-spreading': 'off',
+      'react/jsx-wrap-multilines': 'off',
+      'react/no-access-state-in-setstate': 'warn',
+      'react/no-array-index-key': 'off',
+      'react/no-did-update-set-state': 'warn',
+      'react/no-will-update-set-state': 'warn',
+      'react/prop-types': 'off',
+      'react/static-property-placement': 'off',
+    },
+  },
+
+  // --- Web Worker file — add worker globals so importScripts/self/etc. are known ---
+  {
+    files: ['src/**/webworker.js'],
+    languageOptions: {
+      globals: {
+        ...globals.worker,
+        ...globals.es2020,
+        loadPyodide: 'readonly',
+      },
+    },
+  },
+
+  // --- Plain JS/JSX source files ---
+  {
+    files: ['src/**/*.{js,jsx}'],
+    languageOptions: {
+      ecmaVersion: 2020,
+      sourceType: 'module',
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+        ...globals.es2020,
+      },
+    },
+    plugins: {
+      prettier: prettierPlugin,
+    },
+    settings: {
+      react: { version: 'detect' },
+    },
+    rules: {
+      ...prettierConfig.rules,
+      'prettier/prettier': 'warn',
+      '@typescript-eslint/no-unused-vars': 'warn',
+      'no-param-reassign': 'off',
+      'no-plusplus': 'off',
+    },
+  },
+
+  // --- Internals scripts — Node.js, more relaxed ---
+  {
+    files: ['internals/**/*.{js,mjs,ts}'],
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        ...globals.es2020,
+      },
+    },
+    rules: {
+      'no-console': 'off',
+      '@typescript-eslint/no-require-imports': 'off',
+      'import/no-extraneous-dependencies': 'off',
+    },
+  },
+];
diff --git a/internals/scripts/.eslintrc b/internals/scripts/.eslintrc
deleted file mode 100644
index 35dc618..0000000
--- a/internals/scripts/.eslintrc
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  "rules": {
-    "no-console": "off",
-    "global-require": "off",
-    "import/no-dynamic-require": "off",
-    "import/no-extraneous-dependencies": "off"
-  }
-}
diff --git a/package.json b/package.json
index d27928a..bdff487 100644
--- a/package.json
+++ b/package.json
@@ -16,12 +16,12 @@
     "package-linux": "npm run build && electron-builder build --linux",
     "package-win": "npm run build && electron-builder build --win --x64",
     "postinstall": "electron-builder install-app-deps && node internals/scripts/InstallPyodide.js && node internals/scripts/patchDeps.mjs",
-    "lint": "cross-env NODE_ENV=development eslint . --cache --ext .js,.jsx,.ts,.tsx",
+    "lint": "cross-env NODE_ENV=development eslint . --cache",
     "lint-fix": "npm run lint -- --fix",
-    "lint-styles": "stylelint --ignore-path .eslintignore '**/*.*(css|scss)' --syntax scss",
+    "lint-styles": "stylelint '**/*.*(css|scss)'",
     "lint-styles-fix": "npm run lint-styles -- --fix; exit 0",
-    "postlint-fix": "prettier --ignore-path .eslintignore --single-quote --write '**/*.{js,jsx,json,html,css,less,scss,yml}'",
-    "postlint-styles-fix": "prettier --ignore-path .eslintignore --single-quote --write '**/*.{css,scss}'",
+    "postlint-fix": "prettier --single-quote --write '**/*.{js,jsx,json,html,css,less,scss,yml}'",
+    "postlint-styles-fix": "prettier --single-quote --write '**/*.{css,scss}'",
     "test": "cross-env jest --passWithNoTests",
     "test-all": "npm run lint && npm run tsc && npm run build && npm test",
     "tsc": "tsc --noEmit"
@@ -30,15 +30,15 @@
     "*.{js,jsx,ts,tsx}": [
       "cross-env NODE_ENV=development eslint --cache"
     ],
-    "{*.json,.{eslintrc,prettierrc,stylelintrc}}": [
-      "prettier --ignore-path .eslintignore --parser json --write"
+    "{*.json,.{prettierrc,stylelintrc}}": [
+      "prettier --parser json --write"
     ],
     "*.{css,scss}": [
-      "stylelint --ignore-path .eslintignore --syntax scss --fix",
-      "prettier --ignore-path .eslintignore --single-quote --write"
+      "stylelint --fix",
+      "prettier --single-quote --write"
     ],
     "*.{html,md,yml}": [
-      "prettier --ignore-path .eslintignore --single-quote --write"
+      "prettier --single-quote --write"
     ]
   },
   "build": {
@@ -135,7 +135,10 @@
   ],
   "homepage": "https://github.com/makebrainwaves/BrainWaves/",
   "jest": {
-    "testURL": "http://localhost/",
+    "testEnvironment": "node",
+    "testEnvironmentOptions": {
+      "url": "http://localhost/"
+    },
     "moduleNameMapper": {
       "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/internals/mocks/fileMock.js",
       "\\.(css|less|sass|scss)$": "identity-obj-proxy"
@@ -149,14 +152,13 @@
     ],
     "moduleDirectories": [
       "node_modules"
-    ],
-    "setupFiles": []
+    ]
   },
   "devDependencies": {
     "@babel/plugin-proposal-class-properties": "^7.10.4",
     "@babel/plugin-proposal-decorators": "^7.10.5",
     "@types/history": "^4.7.6",
-    "@types/jest": "^26.0.5",
+    "@types/jest": "^30.0.0",
     "@types/node": "^22.12.0",
     "@types/react": "^16.9.38",
     "@types/react-dom": "^16.9.8",
diff --git a/src/renderer/constants/constants.ts b/src/renderer/constants/constants.ts
index d8d3047..1b87090 100644
--- a/src/renderer/constants/constants.ts
+++ b/src/renderer/constants/constants.ts
@@ -51,14 +51,17 @@ export enum PYODIDE_VARIABLE_NAMES {
 
 export const SEARCH_TIMER = 3000;
 
-// NOTE: the actual marker id values of stimulus 1 and 2 are reversed
+// NOTE: TARGET/NONTARGET are intentional semantic aliases for STIMULUS_2/STIMULUS_1
+// because the actual marker id values of stimulus 1 and 2 are reversed.
 export enum EVENTS {
   STIMULUS_1 = 1,
   STIMULUS_2 = 2,
   STIMULUS_3 = 3,
   STIMULUS_4 = 4,
+  /* eslint-disable @typescript-eslint/no-duplicate-enum-values */
   TARGET = 2,
   NONTARGET = 1,
+  /* eslint-enable @typescript-eslint/no-duplicate-enum-values */
 }
 
 export const CHANNELS = {
diff --git a/src/renderer/store/configureStore.dev.js b/src/renderer/store/configureStore.dev.js
deleted file mode 100644
index bdd8605..0000000
--- a/src/renderer/store/configureStore.dev.js
+++ /dev/null
@@ -1,76 +0,0 @@
-import { createStore, applyMiddleware, compose } from 'redux';
-import thunk from 'redux-thunk';
-import { createEpicMiddleware } from 'redux-observable';
-import { createHashHistory } from 'history';
-import { routerMiddleware, routerActions } from 'react-router-redux';
-import { createLogger } from 'redux-logger';
-import rootReducer from '../reducers';
-import rootEpic from '../epics';
-import * as pyodideActions from '../actions/pyodideActions';
-import * as deviceActions from '../actions/deviceActions';
-
-const history = createHashHistory();
-
-const configureStore = (initialState?: AppState) => {
-  // Redux Configuration
-  const middleware = [];
-  const enhancers = [];
-
-  // Thunk Middleware
-  middleware.push(thunk);
-
-  // Redux Observable (Epic) Middleware
-  const epicMiddleware = createEpicMiddleware();
-  middleware.push(epicMiddleware);
-
-  // Logging Middleware
-  const logger = createLogger({
-    level: 'info',
-    collapsed: true,
-  });
-
-  // Skip redux logs in console during the tests
-  if (import.meta.env.MODE !== 'test') {
-    middleware.push(logger);
-  }
-
-  // Router Middleware
-  const router = routerMiddleware(history);
-  middleware.push(router);
-
-  // Redux DevTools Configuration
-  const actionCreators = {
-    ...deviceActions,
-    ...pyodideActions,
-    ...routerActions,
-  };
-  // If Redux DevTools Extension is installed use it, otherwise use Redux compose
-  /* eslint-disable no-underscore-dangle */
-  const composeEnhancers = window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__
-    ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__({
-        // Options: http://zalmoxisus.github.io/redux-devtools-extension/API/Arguments.html
-        actionCreators,
-      })
-    : compose;
-  /* eslint-enable no-underscore-dangle */
-
-  // Apply Middleware & Compose Enhancers
-  enhancers.push(applyMiddleware(...middleware));
-  const enhancer = composeEnhancers(...enhancers);
-
-  // Create Store
-  const store = createStore(rootReducer, initialState, enhancer);
-
-  if (import.meta.hot) {
-    import.meta.hot.accept('../reducers', (newModule) => {
-      store.replaceReducer(newModule?.default ?? newModule);
-    });
-  }
-
-  // Redux Observable
-  epicMiddleware.run(rootEpic);
-
-  return store;
-};
-
-export default { configureStore, history };
diff --git a/test/.eslintrc.json b/test/.eslintrc.json
deleted file mode 100644
index 9adaad7..0000000
--- a/test/.eslintrc.json
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "extends": "plugin:testcafe/recommended",
-  "env": {
-    "jest/globals": true
-  },
-  "plugins": ["jest", "testcafe"],
-  "rules": {
-    "jest/no-disabled-tests": "warn",
-    "jest/no-focused-tests": "error",
-    "jest/no-identical-title": "error",
-    "no-console": "off"
-  }
-}