diff --git a/eslint.config.js b/eslint.config.js
index c7045d6c..854037f5 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -96,6 +96,11 @@ file that was distributed with this source code.`,
             // In TypeScript files, types live in the signature, not in JSDoc.
             'jsdoc/require-param': 'off',
             'jsdoc/require-returns': 'off',
+            // tsc owns module resolution for `.ts` files (strict, build fails on
+            // a missing import). eslint-plugin-n is not TS-aware: from a `.ts`
+            // file it rewrites `.js` -> `.ts` and cannot resolve imports of
+            // not-yet-migrated `.js` modules. `.js` files keep the rule.
+            'n/no-missing-import': 'off',
         },
     },
     {
diff --git a/lib/EncoreProxy.js b/lib/EncoreProxy.js
index c11f8250..2de1f339 100644
--- a/lib/EncoreProxy.js
+++ b/lib/EncoreProxy.js
@@ -10,7 +10,7 @@
 import levenshtein from 'fastest-levenshtein';
 import pc from 'picocolors';
 
-import prettyError from './utils/pretty-error.js';
+import prettyError from './utils/pretty-error.ts';
 
 // Public methods that were removed. We show an explicit migration message instead of relying on
 // the generic "did you mean" suggestion below, whose closest Levenshtein match would be misleading.
diff --git a/lib/config-generator.js b/lib/config-generator.js
index 553a7e40..35a47112 100644
--- a/lib/config-generator.js
+++ b/lib/config-generator.js
@@ -43,9 +43,9 @@ import notifierPluginUtil from './plugins/notifier.js';
 import PluginPriorities from './plugins/plugin-priorities.js';
 import variableProviderPluginUtil from './plugins/variable-provider.js';
 import vuePluginUtil from './plugins/vue.js';
-import applyOptionsCallback from './utils/apply-options-callback.js';
-import copyEntryTmpName from './utils/copyEntryTmpName.js';
-import getVueVersion from './utils/get-vue-version.js';
+import applyOptionsCallback from './utils/apply-options-callback.ts';
+import copyEntryTmpName from './utils/copyEntryTmpName.ts';
+import getVueVersion from './utils/get-vue-version.ts';
 import stringEscaper from './utils/string-escaper.ts';
 
 class ConfigGenerator {
diff --git a/lib/config/parse-runtime.js b/lib/config/parse-runtime.js
index 33d3cfb3..d3b77ad2 100644
--- a/lib/config/parse-runtime.js
+++ b/lib/config/parse-runtime.js
@@ -9,7 +9,7 @@
 
 import path from 'path';
 
-import packageUp from '../utils/package-up.js';
+import packageUp from '../utils/package-up.ts';
 import RuntimeConfig from './RuntimeConfig.js';
 
 /**
diff --git a/lib/friendly-errors/transformers/missing-loader.js b/lib/friendly-errors/transformers/missing-loader.js
index 2b0e5df3..afff0045 100644
--- a/lib/friendly-errors/transformers/missing-loader.js
+++ b/lib/friendly-errors/transformers/missing-loader.js
@@ -7,7 +7,7 @@
  * file that was distributed with this source code.
  */
 
-import getVueVersion from '../../utils/get-vue-version.js';
+import getVueVersion from '../../utils/get-vue-version.ts';
 
 const TYPE = 'loader-not-enabled';
 
diff --git a/lib/loaders/babel.js b/lib/loaders/babel.js
index 34df4368..2044f16e 100644
--- a/lib/loaders/babel.js
+++ b/lib/loaders/babel.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 
 export default {
     /**
diff --git a/lib/loaders/css-extract.js b/lib/loaders/css-extract.js
index b26282cd..52b48085 100644
--- a/lib/loaders/css-extract.js
+++ b/lib/loaders/css-extract.js
@@ -15,7 +15,7 @@ import { fileURLToPath } from 'url';
 
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 
 export default {
     /**
diff --git a/lib/loaders/css.js b/lib/loaders/css.js
index b146c4e8..0723d1d2 100644
--- a/lib/loaders/css.js
+++ b/lib/loaders/css.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 
 export default {
     /**
diff --git a/lib/loaders/handlebars.js b/lib/loaders/handlebars.js
index 3ea12d9e..264f439e 100644
--- a/lib/loaders/handlebars.js
+++ b/lib/loaders/handlebars.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 
 export default {
     /**
diff --git a/lib/loaders/less.js b/lib/loaders/less.js
index 16216fe8..3f7bc129 100644
--- a/lib/loaders/less.js
+++ b/lib/loaders/less.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import cssLoader from './css.js';
 
 export default {
diff --git a/lib/loaders/sass.js b/lib/loaders/sass.js
index 516a6cbc..8c24fbd9 100644
--- a/lib/loaders/sass.js
+++ b/lib/loaders/sass.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import cssLoader from './css.js';
 
 export default {
diff --git a/lib/loaders/stylus.js b/lib/loaders/stylus.js
index 3dc143be..a908c84f 100644
--- a/lib/loaders/stylus.js
+++ b/lib/loaders/stylus.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import cssLoader from './css.js';
 
 export default {
diff --git a/lib/loaders/typescript.js b/lib/loaders/typescript.js
index 95a3014a..a27048fa 100644
--- a/lib/loaders/typescript.js
+++ b/lib/loaders/typescript.js
@@ -14,7 +14,7 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import babelLoader from './babel.js';
 
 export default {
diff --git a/lib/loaders/vue.js b/lib/loaders/vue.js
index 9b811a23..aaf1cdc4 100644
--- a/lib/loaders/vue.js
+++ b/lib/loaders/vue.js
@@ -14,8 +14,8 @@
 import { fileURLToPath } from 'url';
 
 import loaderFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
-import getVueVersion from '../utils/get-vue-version.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
+import getVueVersion from '../utils/get-vue-version.ts';
 
 export default {
     /**
diff --git a/lib/plugins/css-minimizer.js b/lib/plugins/css-minimizer.js
index 92068b7e..3a0f5313 100644
--- a/lib/plugins/css-minimizer.js
+++ b/lib/plugins/css-minimizer.js
@@ -13,8 +13,8 @@
 
 import MinimizerPlugin from 'minimizer-webpack-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
-import { checkCssMinifierPackages } from '../utils/minifier-check.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
+import { checkCssMinifierPackages } from '../utils/minifier-check.ts';
 
 /**
  * @param {WebpackConfig} webpackConfig
diff --git a/lib/plugins/define.js b/lib/plugins/define.js
index da5998c4..bae4f5a5 100644
--- a/lib/plugins/define.js
+++ b/lib/plugins/define.js
@@ -13,7 +13,7 @@
 
 import webpack from 'webpack';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import PluginPriorities from './plugin-priorities.js';
 
 /**
diff --git a/lib/plugins/delete-unused-entries.js b/lib/plugins/delete-unused-entries.js
index 79287400..c0a02e60 100644
--- a/lib/plugins/delete-unused-entries.js
+++ b/lib/plugins/delete-unused-entries.js
@@ -11,7 +11,7 @@
  * @import WebpackConfig from '../WebpackConfig.js'
  */
 
-import copyEntryTmpName from '../utils/copyEntryTmpName.js';
+import copyEntryTmpName from '../utils/copyEntryTmpName.ts';
 import DeleteUnusedEntriesJSPlugin from '../webpack/delete-unused-entries-js-plugin.js';
 import PluginPriorities from './plugin-priorities.js';
 
diff --git a/lib/plugins/forked-ts-types.js b/lib/plugins/forked-ts-types.js
index b8574f25..ad4e7c4f 100644
--- a/lib/plugins/forked-ts-types.js
+++ b/lib/plugins/forked-ts-types.js
@@ -13,7 +13,7 @@
 
 import ForkTsCheckerWebpackPlugin from 'fork-ts-checker-webpack-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import PluginPriorities from './plugin-priorities.js';
 
 /**
diff --git a/lib/plugins/friendly-errors.js b/lib/plugins/friendly-errors.js
index 2a6057d5..967ac5d1 100644
--- a/lib/plugins/friendly-errors.js
+++ b/lib/plugins/friendly-errors.js
@@ -19,7 +19,7 @@ import missingPostCssConfigFormatter from '../friendly-errors/formatters/missing
 import missingCssFileTransformer from '../friendly-errors/transformers/missing-css-file.js';
 import missingLoaderTransformerFactory from '../friendly-errors/transformers/missing-loader.js';
 import missingPostCssConfigTransformer from '../friendly-errors/transformers/missing-postcss-config.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 
 /**
  * @param {WebpackConfig} webpackConfig
diff --git a/lib/plugins/js-minimizer.js b/lib/plugins/js-minimizer.js
index 99184ae9..15ccd842 100644
--- a/lib/plugins/js-minimizer.js
+++ b/lib/plugins/js-minimizer.js
@@ -13,8 +13,8 @@
 
 import MinimizerPlugin from 'minimizer-webpack-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
-import { checkJsMinifierPackages } from '../utils/minifier-check.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
+import { checkJsMinifierPackages } from '../utils/minifier-check.ts';
 
 /**
  * @param {WebpackConfig} webpackConfig
diff --git a/lib/plugins/manifest.js b/lib/plugins/manifest.js
index 94ab2df7..d86fc1f6 100644
--- a/lib/plugins/manifest.js
+++ b/lib/plugins/manifest.js
@@ -13,9 +13,9 @@
 
 import { WebpackManifestPlugin } from 'webpack-manifest-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
-import copyEntryTmpName from '../utils/copyEntryTmpName.js';
-import manifestKeyPrefixHelper from '../utils/manifest-key-prefix-helper.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
+import copyEntryTmpName from '../utils/copyEntryTmpName.ts';
+import manifestKeyPrefixHelper from '../utils/manifest-key-prefix-helper.ts';
 import PluginPriorities from './plugin-priorities.js';
 
 /**
diff --git a/lib/plugins/mini-css-extract.js b/lib/plugins/mini-css-extract.js
index 2fb84864..bf0bbecb 100644
--- a/lib/plugins/mini-css-extract.js
+++ b/lib/plugins/mini-css-extract.js
@@ -13,7 +13,7 @@
 
 import MiniCssExtractPlugin from 'mini-css-extract-plugin';
 
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import PluginPriorities from './plugin-priorities.js';
 
 /**
diff --git a/lib/plugins/notifier.js b/lib/plugins/notifier.js
index 885d440f..abd9ed3f 100644
--- a/lib/plugins/notifier.js
+++ b/lib/plugins/notifier.js
@@ -12,7 +12,7 @@
  */
 
 import pluginFeatures from '../features.js';
-import applyOptionsCallback from '../utils/apply-options-callback.js';
+import applyOptionsCallback from '../utils/apply-options-callback.ts';
 import PluginPriorities from './plugin-priorities.js';
 
 /**
diff --git a/lib/utils/apply-options-callback.js b/lib/utils/apply-options-callback.ts
similarity index 53%
rename from lib/utils/apply-options-callback.js
rename to lib/utils/apply-options-callback.ts
index ac28bc97..befbba7e 100644
--- a/lib/utils/apply-options-callback.js
+++ b/lib/utils/apply-options-callback.ts
@@ -7,19 +7,17 @@
  * file that was distributed with this source code.
  */
 
-/**
- * @typedef {function(this: T, T, ...*): T|void} OptionsCallback
- * @template {object} T
- */
+export type OptionsCallback<T extends object> = (
+    this: T,
+    options: T,
+    ...extraArgs: any[]
+) => T | void;
 
-/**
- * @template {object} T
- * @param {OptionsCallback<T>} optionsCallback
- * @param {T} options
- * @param {...*} extraArgs  Forwarded to the callback after `options`
- * @returns {T}
- */
-export default function (optionsCallback, options, ...extraArgs) {
+export default function <T extends object>(
+    optionsCallback: OptionsCallback<T>,
+    options: T,
+    ...extraArgs: any[]
+): T {
     const result = optionsCallback.call(options, options, ...extraArgs);
 
     if (typeof result === 'object') {
diff --git a/lib/utils/copyEntryTmpName.js b/lib/utils/copyEntryTmpName.ts
similarity index 100%
rename from lib/utils/copyEntryTmpName.js
rename to lib/utils/copyEntryTmpName.ts
diff --git a/lib/utils/get-vue-version.js b/lib/utils/get-vue-version.ts
similarity index 87%
rename from lib/utils/get-vue-version.js
rename to lib/utils/get-vue-version.ts
index f0c56a47..4deb4bd2 100644
--- a/lib/utils/get-vue-version.js
+++ b/lib/utils/get-vue-version.ts
@@ -7,20 +7,13 @@
  * file that was distributed with this source code.
  */
 
-/**
- * @import WebpackConfig from '../WebpackConfig.js'
- */
-
 import semver from 'semver';
 
 import logger from '../logger.js';
 import packageHelper from '../package-helper.js';
+import type WebpackConfig from '../WebpackConfig.js';
 
-/**
- * @param {WebpackConfig} webpackConfig
- * @returns {number|string|null}
- */
-export default function (webpackConfig) {
+export default function (webpackConfig: WebpackConfig): number | string | null {
     if (webpackConfig.vueOptions.version !== null) {
         return webpackConfig.vueOptions.version;
     }
diff --git a/lib/utils/manifest-key-prefix-helper.js b/lib/utils/manifest-key-prefix-helper.ts
similarity index 81%
rename from lib/utils/manifest-key-prefix-helper.js
rename to lib/utils/manifest-key-prefix-helper.ts
index aeb173bb..e638cc28 100644
--- a/lib/utils/manifest-key-prefix-helper.js
+++ b/lib/utils/manifest-key-prefix-helper.ts
@@ -7,17 +7,12 @@
  * file that was distributed with this source code.
  */
 
-/**
- * @import WebpackConfig from '../WebpackConfig.js'
- */
+import type WebpackConfig from '../WebpackConfig.js';
 
 /**
  * Helper for determining the manifest.json key prefix.
- *
- * @param {WebpackConfig} webpackConfig
- * @returns {string}
  */
-export default function (webpackConfig) {
+export default function (webpackConfig: WebpackConfig): string {
     let manifestPrefix = webpackConfig.manifestKeyPrefix;
     if (null === manifestPrefix) {
         if (null === webpackConfig.publicPath) {
diff --git a/lib/utils/minifier-check.js b/lib/utils/minifier-check.ts
similarity index 87%
rename from lib/utils/minifier-check.js
rename to lib/utils/minifier-check.ts
index 1a73ea0b..f2f90687 100644
--- a/lib/utils/minifier-check.js
+++ b/lib/utils/minifier-check.ts
@@ -11,13 +11,13 @@ import MinimizerPlugin from 'minimizer-webpack-plugin';
 
 import Features from '../features.js';
 
-const JS_MINIFIER_FEATURES = new Map([
+const JS_MINIFIER_FEATURES = new Map<Function, string>([
     [MinimizerPlugin.esbuildMinify, 'minify-js-esbuild'],
     [MinimizerPlugin.swcMinify, 'minify-js-swc'],
     [MinimizerPlugin.uglifyJsMinify, 'minify-js-uglify'],
 ]);
 
-const CSS_MINIFIER_FEATURES = new Map([
+const CSS_MINIFIER_FEATURES = new Map<Function, string>([
     [MinimizerPlugin.lightningCssMinify, 'minify-css-lightningcss'],
     [MinimizerPlugin.cssnanoMinify, 'minify-css-cssnano'],
     [MinimizerPlugin.cssoMinify, 'minify-css-csso'],
@@ -26,10 +26,7 @@ const CSS_MINIFIER_FEATURES = new Map([
     [MinimizerPlugin.swcMinifyCss, 'minify-css-swc'],
 ]);
 
-/**
- * @param {Function} minifyFn
- */
-export function checkJsMinifierPackages(minifyFn) {
+export function checkJsMinifierPackages(minifyFn: Function): void {
     const feature = JS_MINIFIER_FEATURES.get(minifyFn);
     if (!feature) {
         // terserMinify (bundled) or a custom function: nothing to install
@@ -39,10 +36,7 @@ export function checkJsMinifierPackages(minifyFn) {
     Features.ensurePackagesExistAndAreCorrectVersion(feature);
 }
 
-/**
- * @param {Function|undefined} minifyFn
- */
-export function checkCssMinifierPackages(minifyFn) {
+export function checkCssMinifierPackages(minifyFn: Function | undefined): void {
     if (!minifyFn) {
         throw new Error(
             'CSS minification is enabled but no CSS minifier is configured. ' +
diff --git a/lib/utils/package-up.js b/lib/utils/package-up.ts
similarity index 64%
rename from lib/utils/package-up.js
rename to lib/utils/package-up.ts
index 92a27a26..39a830b2 100644
--- a/lib/utils/package-up.js
+++ b/lib/utils/package-up.ts
@@ -14,31 +14,25 @@ import { fileURLToPath } from 'url';
 /**
  * Inlined version of the package "package-up" (ESM only).
  *
- * @param {object} options
- * @param {string} options.cwd The directory to start searching from.
- * @returns {string|undefined} The path to the nearest package.json file or undefined if not found.
+ * Returns the path to the nearest package.json file, or undefined if not found.
  */
-export default function ({ cwd }) {
+export default function ({ cwd }: { cwd: string }): string | undefined {
     return findUpSync('package.json', { cwd });
 }
 
-/**
- * @param {string|URL} urlOrPath
- * @returns {string}
- */
-function toPath(urlOrPath) {
+function toPath(urlOrPath: string | URL): string {
     return urlOrPath instanceof URL ? fileURLToPath(urlOrPath) : urlOrPath;
 }
 
 /**
  * Inlined and simplified version of the package "find-up-simple" (ESM only).
  *
- * @param {string} name The name of the file to find
- * @param {object} options
- * @param {string=} options.cwd The directory to start searching from.
- * @returns {string|undefined} The path to the file found or undefined if not found.
+ * Returns the path to the file found, or undefined if not found.
  */
-function findUpSync(name, { cwd = process.cwd() } = {}) {
+function findUpSync(
+    name: string,
+    { cwd = process.cwd() }: { cwd?: string } = {}
+): string | undefined {
     let directory = path.resolve(toPath(cwd) || '');
     const { root } = path.parse(directory);
 
diff --git a/lib/utils/pretty-error.js b/lib/utils/pretty-error.ts
similarity index 66%
rename from lib/utils/pretty-error.js
rename to lib/utils/pretty-error.ts
index db0d0b5a..ec11d9a6 100644
--- a/lib/utils/pretty-error.js
+++ b/lib/utils/pretty-error.ts
@@ -15,18 +15,14 @@ const PrettyError = require('pretty-error');
 /**
  * Render a pretty version of the given error.
  *
- * Supported options:
- *      - {Function} skipTrace
- *              An optional callback that defines whether
- *              or not each line of the eventual stacktrace
- *              should be kept. First argument is the content
- *              of the line, second argument is the line number.
- *
- * @param {*} error
- * @param {object} options
- * @returns {void}
+ * The optional `skipTrace` callback defines whether or not each line of the
+ * eventual stacktrace should be kept. First argument is the content of the
+ * line, second argument is the line number.
  */
-export default function (error, options = {}) {
+export default function (
+    error: unknown,
+    options: { skipTrace?: (line: string, lineNumber: number) => boolean } = {}
+): void {
     const pe = new PrettyError();
 
     // Use the default terminal's color
diff --git a/lib/webpack/entry-points-plugin.js b/lib/webpack/entry-points-plugin.js
index 130da5c3..163443d2 100644
--- a/lib/webpack/entry-points-plugin.js
+++ b/lib/webpack/entry-points-plugin.js
@@ -11,7 +11,7 @@ import crypto from 'crypto';
 import fs from 'fs';
 import path from 'path';
 
-import copyEntryTmpName from '../utils/copyEntryTmpName.js';
+import copyEntryTmpName from '../utils/copyEntryTmpName.ts';
 
 /**
  * Return the file extension from a filename, without the leading dot and without the query string (if any).
diff --git a/package.json b/package.json
index 45e2358d..469350a1 100644
--- a/package.json
+++ b/package.json
@@ -71,6 +71,7 @@
         "@symfony/stimulus-bridge": "^3.0.0 || ^4.0.0",
         "@tsconfig/node22": "^22.0.5",
         "@types/node": "^22.18.0",
+        "@types/semver": "^7.7.1",
         "@vue/babel-plugin-jsx": "^3.0.0",
         "@vue/compiler-sfc": "^3.2.14",
         "autoprefixer": "^10.2.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index ffc05200..55230ea7 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -90,6 +90,9 @@ importers:
       '@types/node':
         specifier: ^22.18.0
         version: 22.20.0
+      '@types/semver':
+        specifier: ^7.7.1
+        version: 7.7.1
       '@vue/babel-plugin-jsx':
         specifier: ^3.0.0
         version: 3.0.0(@babel/core@8.0.1)
@@ -1671,6 +1674,9 @@ packages:
   '@types/retry@0.12.2':
     resolution: {integrity: sha512-XISRgDJ2Tc5q4TRqvgJtzsRkFYNJzZrhTdtMoGVBttwzzQJkPnS3WWTFc7kuDRoPtPakl+T+OfdEUjYJj7Jbow==}
 
+  '@types/semver@7.7.1':
+    resolution: {integrity: sha512-FmgJfu+MOcQ370SD0ev7EI8TlCAfKYU+B4m5T3yXc1CiRN94g/SZPtsCkk506aUDtlMnFZvasDwHHUcZUEaYuA==}
+
   '@types/send@0.17.6':
     resolution: {integrity: sha512-Uqt8rPBE8SY0RK8JB1EzVOIZ32uqy8HwdxCnoCOsYrvnswqmFZ/k+9Ikidlk/ImhsdvBsloHbAlewb2IEBV/Og==}
 
@@ -6438,6 +6444,8 @@ snapshots:
 
   '@types/retry@0.12.2': {}
 
+  '@types/semver@7.7.1': {}
+
   '@types/send@0.17.6':
     dependencies:
       '@types/mime': 1.3.5
diff --git a/test/functional.js b/test/functional.js
index e29b16e9..39e5fc52 100644
--- a/test/functional.js
+++ b/test/functional.js
@@ -17,7 +17,7 @@ import semver from 'semver';
 import { afterAll, beforeAll, chai, describe, expect, it } from 'vitest';
 
 import packageHelper from '../lib/package-helper.js';
-import getVueVersion from '../lib/utils/get-vue-version.js';
+import getVueVersion from '../lib/utils/get-vue-version.ts';
 import { assertWarning } from './helpers/logger-assert.js';
 import * as testSetup from './helpers/setup.js';
 
diff --git a/test/plugins/css-minimizer.js b/test/plugins/css-minimizer.js
index 8486b695..d795f160 100644
--- a/test/plugins/css-minimizer.js
+++ b/test/plugins/css-minimizer.js
@@ -17,7 +17,7 @@ const { checkCssMinifierPackages } = vi.hoisted(() => ({
     checkCssMinifierPackages: vi.fn(),
 }));
 
-vi.mock('../../lib/utils/minifier-check.js', () => ({
+vi.mock('../../lib/utils/minifier-check.ts', () => ({
     checkJsMinifierPackages: vi.fn(),
     checkCssMinifierPackages,
 }));
diff --git a/test/plugins/js-minimizer.js b/test/plugins/js-minimizer.js
index 3132429c..bf6a1b07 100644
--- a/test/plugins/js-minimizer.js
+++ b/test/plugins/js-minimizer.js
@@ -17,7 +17,7 @@ const { checkJsMinifierPackages } = vi.hoisted(() => ({
     checkJsMinifierPackages: vi.fn(),
 }));
 
-vi.mock('../../lib/utils/minifier-check.js', () => ({
+vi.mock('../../lib/utils/minifier-check.ts', () => ({
     checkJsMinifierPackages,
     checkCssMinifierPackages: vi.fn(),
 }));
diff --git a/test/utils/apply-options-callback.js b/test/utils/apply-options-callback.js
index e52cd06c..cd6501d2 100644
--- a/test/utils/apply-options-callback.js
+++ b/test/utils/apply-options-callback.js
@@ -9,7 +9,7 @@
 
 import { describe, it, expect } from 'vitest';
 
-import applyOptionsCallback from '../../lib/utils/apply-options-callback.js';
+import applyOptionsCallback from '../../lib/utils/apply-options-callback.ts';
 
 describe('utils/apply-options-callback', function () {
     it('mutates and returns the options object', function () {
diff --git a/test/utils/get-vue-version.js b/test/utils/get-vue-version.js
index 0a76b5b8..f322bab7 100644
--- a/test/utils/get-vue-version.js
+++ b/test/utils/get-vue-version.js
@@ -11,7 +11,7 @@ import { vi, describe, it, expect } from 'vitest';
 
 import RuntimeConfig from '../../lib/config/RuntimeConfig.js';
 import packageHelper from '../../lib/package-helper.js';
-import getVueVersion from '../../lib/utils/get-vue-version.js';
+import getVueVersion from '../../lib/utils/get-vue-version.ts';
 import WebpackConfig from '../../lib/WebpackConfig.js';
 
 const createWebpackConfig = function () {
diff --git a/test/utils/minifier-check.js b/test/utils/minifier-check.js
index 925edf07..99f2fcab 100644
--- a/test/utils/minifier-check.js
+++ b/test/utils/minifier-check.js
@@ -19,7 +19,7 @@ vi.mock('../../lib/features.js', () => ({
 }));
 
 const { checkJsMinifierPackages, checkCssMinifierPackages } =
-    await import('../../lib/utils/minifier-check.js');
+    await import('../../lib/utils/minifier-check.ts');
 
 describe('utils/minifier-check', function () {
     beforeEach(() => ensurePackagesExistAndAreCorrectVersion.mockReset());
diff --git a/test/utils/package-up.js b/test/utils/package-up.js
index 367f0976..b2db048b 100644
--- a/test/utils/package-up.js
+++ b/test/utils/package-up.js
@@ -11,7 +11,7 @@ import { resolve as resolvePath } from 'path';
 
 import { describe, it, expect } from 'vitest';
 
-import packageUp from '../../lib/utils/package-up.js';
+import packageUp from '../../lib/utils/package-up.ts';
 
 describe('package-up', function () {
     it.each([