feat!: require Node 24 and migrate CJS to ESM output

BREAKING CHANGE: Node 24+ is now required. All packages emit ESM.

- Add "type": "module" to all package.json files
- Update exports to use single "default" condition (remove CJS/ESM dual exports)
- Update engines to require Node >=24.0.0
- Delete all index.mjs shim files (34 files)
- Fix CJS interop issues across source files:
  - require.resolve → import.meta.resolve / createRequire
  - __dirname → import.meta.dirname
  - Default import interop for CJS packages (rollup plugins, saucelabs, etc.)
- Add .nvmrc (v24.11.1)
- Add changeset for breaking node version requirement

Assisted-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bennypowers

.changeset/node-24-lts-requirement.md

@@ -0,0 +1,51 @@
+---
+"@web/browser-logs": major
+"@web/config-loader": major
+"@web/dev-server": major
+"@web/dev-server-core": major
+"@web/dev-server-esbuild": major
+"@web/dev-server-hmr": major
+"@web/dev-server-import-maps": major
+"@web/dev-server-legacy": major
+"@web/dev-server-polyfill": major
+"@web/dev-server-rollup": major
+"@web/dev-server-storybook": major
+"@web/mocks": major
+"@web/parse5-utils": major
+"@web/polyfills-loader": major
+"@web/rollup-plugin-copy": major
+"@web/rollup-plugin-html": major
+"@web/rollup-plugin-import-meta-assets": major
+"@web/rollup-plugin-polyfills-loader": major
+"@web/rollup-plugin-workbox": major
+"@web/storybook-builder": major
+"@web/storybook-framework-web-components": major
+"@web/storybook-utils": major
+"@web/test-runner": major
+"@web/test-runner-browserstack": major
+"@web/test-runner-chrome": major
+"@web/test-runner-cli": major
+"@web/test-runner-commands": major
+"@web/test-runner-core": major
+"@web/test-runner-coverage-v8": major
+"@web/test-runner-junit-reporter": major
+"@web/test-runner-mocha": major
+"@web/test-runner-module-mocking": major
+"@web/test-runner-playwright": major
+"@web/test-runner-puppeteer": major
+"@web/test-runner-saucelabs": major
+"@web/test-runner-selenium": major
+"@web/test-runner-visual-regression": major
+"@web/test-runner-webdriver": major
+---
+
+**BREAKING**: Require Node.js 24 LTS (Iron)
+
+Update minimum Node.js version from 18.0.0 to 24.0.0 across all packages. Node.js 18 reached EOL in April 2025
+
+**Migration:**
+Update your Node.js version to 24 or later:
+```bash
+nvm install 24
+nvm use 24
+```

.nvmrc

@@ -0,0 +1 @@
+v24.11.1

package.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/modernweb-dev/web.git"
   },
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=24.0.0"
   },
   "scripts": {
     "build": "npm run build:clean && tsc --build",

packages/browser-logs/index.mjs

@@ -17,12 +17,11 @@
   "exports": {
     ".": {
       "types": "./index.d.ts",
-      "import": "./index.mjs",
-      "require": "./dist/index.js"
+      "default": "./dist/index.js"
     }
   },
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=24.0.0"
   },
   "scripts": {
     "build": "tsc",
@@ -32,7 +31,6 @@
   "files": [
     "*.d.ts",
     "*.js",
-    "*.mjs",
     "dist",
     "src"
   ],
@@ -52,5 +50,6 @@
   "devDependencies": {
     "@esm-bundle/chai": "^4.1.5",
     "puppeteer": "^24.0.0"
-  }
+  },
+  "type": "module"
 }

packages/browser-logs/package.json

@@ -14,9 +14,9 @@
   "author": "modern-web",
   "homepage": "https://github.com/modernweb-dev/web/tree/master/packages/config-loader",
   "main": "src/index.js",
-  "type": "commonjs",
+  "type": "module",
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=24.0.0"
   },
   "scripts": {
     "build": "tsc",
@@ -26,7 +26,6 @@
   "files": [
     "*.d.ts",
     "*.js",
-    "*.mjs",
     "dist",
     "src"
   ],
@@ -42,9 +41,8 @@
   "types": "dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./index.d.ts",
-      "import": "./index.mjs",
-      "require": "./src/index.js"
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
     }
   }
 }

packages/config-loader/index.mjs

@@ -17,21 +17,19 @@
   "exports": {
     ".": {
       "types": "./index.d.ts",
-      "import": "./index.mjs",
-      "require": "./dist/index.js"
+      "default": "./dist/index.js"
     },
     "./dist/dom5": {
       "types": "./dist/dom5/index.d.ts",
-      "require": "./dist/dom5/index.js"
+      "default": "./dist/dom5/index.js"
     },
     "./test-helpers": {
       "types": "./test-helpers.d.ts",
-      "import": "./test-helpers.mjs",
-      "require": "./dist/test-helpers.js"
+      "default": "./dist/test-helpers.js"
     }
   },
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=24.0.0"
   },
   "scripts": {
     "build": "tsc",
@@ -46,7 +44,6 @@
     ".self-signed-dev-server-ssl.cert",
     ".self-signed-dev-server-ssl.key",
     "*.d.ts",
-    "*.mjs",
     "dist",
     "src"
   ],
@@ -58,24 +55,24 @@
     "core"
   ],
   "dependencies": {
-    "@types/koa": "^2.11.6",
-    "@types/ws": "^7.4.0",
+    "@types/koa": "^3.0.1",
+    "@types/ws": "^8.5.13",
     "@web/parse5-utils": "^2.1.0",
     "chokidar": "^4.0.1",
     "clone": "^2.1.2",
     "es-module-lexer": "^1.0.0",
     "get-stream": "^6.0.0",
     "is-stream": "^2.0.0",
     "isbinaryfile": "^5.0.0",
-    "koa": "^2.16.1",
+    "koa": "^3.1.1",
     "koa-etag": "^4.0.0",
     "koa-send": "^5.0.1",
     "koa-static": "^5.0.0",
     "lru-cache": "^8.0.4",
     "mime-types": "^2.1.27",
-    "parse5": "^6.0.1",
+    "parse5": "^7.0.0 || ^8.0.0",
     "picomatch": "^2.2.2",
-    "ws": "^7.5.10"
+    "ws": "^8.18.3"
   },
   "devDependencies": {
     "@types/clone": "^2.1.0",
@@ -86,5 +83,6 @@
     "express": "^4.21.2",
     "nanoid": "^3.1.25",
     "portfinder": "^1.0.32"
-  }
+  },
+  "type": "module"
 }

packages/config-loader/package.json

@@ -68,7 +68,7 @@ export function createServer(
 
   let server: Server;
   if (cfg.http2) {
-    const dir = path.join(__dirname, '..');
+    const dir = path.join(import.meta.dirname, '..');
     const options = {
       key: fs.readFileSync(
         cfg.sslKey