chore: add github test actions

.github/workflows/test.yml

@@ -0,0 +1,67 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+# Cancel superseded runs on the same ref (e.g. new pushes to a PR).
+concurrency:
+  group: tests-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  unit:
+    name: Unit (happy-dom)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 11
+      - uses: actions/setup-node@v6
+        with:
+          node-version-file: .nvmrc
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm test
+
+  e2e:
+    name: E2E (Chromium + Firefox + WebKit)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 11
+      - uses: actions/setup-node@v6
+        with:
+          node-version-file: .nvmrc
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      # Downloads the browser binaries and their OS libraries (Firefox/WebKit
+      # need system deps that `--with-deps` installs via apt on the runner).
+      - name: Install Playwright browsers
+        run: pnpm exec playwright install --with-deps chromium firefox webkit
+      - run: pnpm test:e2e:all
+
+  size:
+    name: Size limit
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 11
+      - uses: actions/setup-node@v6
+        with:
+          node-version-file: .nvmrc
+          cache: pnpm
+      - run: pnpm install --frozen-lockfile
+      # `pnpm size-limit` builds `dist/` (tsc + esbuild) and checks each entry
+      # against the byte budgets declared in package.json `size-limit`.
+      - run: pnpm size-limit

.husky/pre-commit

@@ -1,4 +1,5 @@
-npm run lint --cache
+# Lean: lint + format staged files, then the fast unit suite.
-npm run test:all
+# Heavier checks (browser e2e, size-limit) run on pre-push; the full
-npm run build
+# cross-browser matrix runs in CI.
-npx size-limit
+pnpm exec lint-staged
+pnpm test

.husky/pre-push

@@ -0,0 +1,4 @@
+# Heavier gate before code leaves the machine: browser e2e (Chromium only —
+# Firefox/WebKit + their system deps are exercised in CI) and the size budget.
+pnpm test:e2e
+pnpm size-limit

AGENTS.md

@@ -17,7 +17,7 @@ This file provides guidance to AI coding agents when working with code in this r
 - `pnpm size-limit` — enforces the byte budgets declared in `package.json` `size-limit` (e.g. `WebComponent.js` ≤ 1.2 KB). Keep additions tiny; this gate is a core project value.
 - `pnpm docs` — run the Astro docs site (`docs/` workspace) locally.
 - `pnpm demo` — run the Vite examples showcase (`demo/` workspace) locally; `pnpm demo:build` builds it.
-- `pnpm test:e2e` — run the browser e2e specs (`test/e2e/`) in Chromium via Vitest browser mode; `pnpm test:all` runs unit + e2e.
+- `pnpm test:e2e` — run the browser e2e specs (`test/e2e/`) via Vitest browser mode (Playwright). Defaults to Chromium; `pnpm test:e2e:firefox` / `:webkit` / `:all` target the other engines (the `E2E_BROWSERS` env var, comma-separated, selects instances). `pnpm test:all` runs unit + default e2e.
 
 pnpm is mandatory (a `preinstall` `only-allow pnpm` guard enforces it). This is a pnpm workspace with two sub-packages: `docs/` (Astro docs site) and `demo/` (Vite examples showcase, which consumes the root `web-component-base` package as a `workspace:*` dependency). The runnable example sources live in `demo/examples/` and import the package by name (`web-component-base`), not via relative `src/` paths.
 

eslint.config.mjs

@@ -12,6 +12,12 @@ export default [
       'no-unused-vars': 'warn',
     },
   },
+  // Config, build, and script files run in Node — give them Node globals
+  // (e.g. `process`) on top of the browser defaults.
+  {
+    files: ['**/*.config.{js,mjs,cjs}', 'scripts/**/*.{js,mjs}'],
+    languageOptions: { globals: globals.node },
+  },
   {
     ignores: ['site/*', '**/dist/*'],
   },

package.json

@@ -30,8 +30,12 @@
     "dev": "pnpm -F demo dev",
     "test": "vitest --run",
     "test:watch": "vitest",
-    "test:e2e": "vitest --run --config vitest.e2e.config.mjs",
+    "test:e2e": "E2E_BROWSERS=chromium vitest --run --config vitest.e2e.config.mjs",
-    "test:all": "pnpm test && pnpm test:e2e",
+    "test:e2e:chromium": "E2E_BROWSERS=chromium vitest --run --config vitest.e2e.config.mjs",
+    "test:e2e:firefox": "E2E_BROWSERS=firefox vitest --run --config vitest.e2e.config.mjs",
+    "test:e2e:webkit": "E2E_BROWSERS=webkit vitest --run --config vitest.e2e.config.mjs",
+    "test:e2e:all": "vitest --run --config vitest.e2e.config.mjs",
+    "test:all": "pnpm test && pnpm test:e2e:all",
     "demo": "pnpm -F demo dev",
     "demo:build": "pnpm -F demo build",
     "docs": "pnpm -F docs start",
@@ -44,6 +48,13 @@
     "lint": "eslint . --config eslint.config.mjs",
     "prepare": "husky"
   },
+  "lint-staged": {
+    "*.{js,mjs,cjs}": [
+      "eslint --config eslint.config.mjs --fix",
+      "prettier --write"
+    ],
+    "*.{json,css,html,md,yml,yaml}": "prettier --write"
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/ayo-run/web-component-base.git"
@@ -73,6 +84,7 @@
     "globals": "^17.1.0",
     "happy-dom": "^20.3.7",
     "husky": "^9.1.7",
+    "lint-staged": "^17.0.8",
     "netlify-cli": "^23.13.5",
     "playwright": "^1.61.1",
     "prettier": "^3.8.1",

pnpm-lock.yaml

@@ -16,13 +16,13 @@ importers:
         version: 12.0.0(size-limit@12.0.0(jiti@2.6.1))
       '@vitest/browser':
         specifier: 4.0.18
-        version: 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)
+        version: 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)
       '@vitest/browser-playwright':
         specifier: 4.0.18
-        version: 4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)
+        version: 4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)
       '@vitest/coverage-v8':
         specifier: 4.0.18
-        version: 4.0.18(@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18))(vitest@4.0.18)
+        version: 4.0.18(@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18))(vitest@4.0.18)
       bumpp:
         specifier: ^11.1.0
         version: 11.1.0
@@ -44,6 +44,9 @@ importers:
       husky:
         specifier: ^9.1.7
         version: 9.1.7
+      lint-staged:
+        specifier: ^17.0.8
+        version: 17.0.8
       netlify-cli:
         specifier: ^23.13.5
         version: 23.13.5(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(picomatch@4.0.3)(rollup@4.60.3)(supports-color@10.2.2)
@@ -70,7 +73,7 @@ importers:
         version: 5.9.3
       vitest:
         specifier: ^4.0.18
-        version: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+        version: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
 
   demo:
     dependencies:
@@ -89,10 +92,10 @@ importers:
     dependencies:
       '@astrojs/starlight':
         specifier: ^0.39.1
-        version: 0.39.1(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2))(typescript@5.9.3)
+        version: 0.39.1(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0))(typescript@5.9.3)
       astro:
         specifier: ^6.3.1
-        version: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2)
+        version: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0)
       sharp:
         specifier: ^0.34.5
         version: 0.34.5
@@ -2680,6 +2683,10 @@ packages:
     resolution: {integrity: sha512-bXfOC4QcT1tKXGorxL3wbJm6XJPDqEnij2gQ2m7ESQuE+/z9YFIWnl/5RpTiKWbMq3EVKR4fRLJGn6DVfu0mpw==}
     engines: {node: '>=18.20'}
 
+  cli-truncate@5.2.0:
+    resolution: {integrity: sha512-xRwvIOMGrfOAnM1JYtqQImuaNtDEv9v6oIYAs4LIHwTiKee8uwvIi363igssOC0O5U04i4AlENs79LQLu9tEMw==}
+    engines: {node: '>=20'}
+
   cli-width@3.0.0:
     resolution: {integrity: sha512-FxqpkPPwu1HjuN93Omfm4h8uIanXofW0RxVEW3k5RKx+mJJYSthzNhp32Kzxxy3YAEZ/Dc/EWN1vZRY0+kOhbw==}
     engines: {node: '>= 10'}
@@ -3690,6 +3697,10 @@ packages:
     resolution: {integrity: sha512-QZjmEOC+IT1uk6Rx0sX22V6uHWVwbdbxf1faPqJ1QhLdGgsRGCZoyaQBm/piRdJy/D2um6hM1UP7ZEeQ4EkP+Q==}
     engines: {node: '>=18'}
 
+  get-east-asian-width@1.6.0:
+    resolution: {integrity: sha512-QRbvDIbx6YklUe6RxeTeleMR0yv3cYH6PsPZHcnVn7xv7zO1BHN8r0XETu8n6Ye3Q+ahtSarc3WgtNWmehIBfA==}
+    engines: {node: '>=18'}
+
   get-intrinsic@1.3.0:
     resolution: {integrity: sha512-9fSjSaos/fRIVIp+xSJlE6lfwhES7LNtKaCBIamHsjr2na1BiABJPo0mOjjz8GJDURarmCPGqaiVg5mfjb98CQ==}
     engines: {node: '>= 0.4'}
@@ -4432,10 +4443,19 @@ packages:
     resolution: {integrity: sha512-/vlFKAoH5Cgt3Ie+JLhRbwOsCQePABiU3tJ1egGvyQ+33R/vcwM2Zl2QR/LzjsBeItPt3oSVXapn+m4nQDvpzw==}
     engines: {node: '>=14'}
 
+  lint-staged@17.0.8:
+    resolution: {integrity: sha512-B2P/d+jVW0UXOQ0MVMLrB/9ydA1P+zz6jYfdrbbEd9ur3S2rcbduFWKiUCC02Sm5hbC8nrm7y24WuYMG54HfxA==}
+    engines: {node: '>=22.22.1'}
+    hasBin: true
+
   listhen@1.9.0:
     resolution: {integrity: sha512-I8oW2+QL5KJo8zXNWX046M134WchxsXC7SawLPvRQpogCbkyQIaFxPE89A2HiwR7vAK2Dm2ERBAmyjTYGYEpBg==}
     hasBin: true
 
+  listr2@10.2.2:
+    resolution: {integrity: sha512-JtNtbZj8q5BnDMR7trpwvwk3RIrANtIVzEUm8w7amp6xelLgyuq+4WZoTH913XaQAoH/cNdYhaNzBPA2U3xbDw==}
+    engines: {node: '>=22.13.0'}
+
   locate-path@6.0.0:
     resolution: {integrity: sha512-iPZK6eYjbxRu3uB4/WZ3EsEIMJFMqAoopl3R+zuq0UjcAm/MO6KCweDgPfP3elTztoKP3KtnVHxTn2NHBSDVUw==}
     engines: {node: '>=10'}
@@ -6027,6 +6047,10 @@ packages:
     resolution: {integrity: sha512-iOBWFgUX7caIZiuutICxVgX1SdxwAVFFKwt1EvMYYec/NWO5meOJ6K5uQxhrYBdQJne4KxiqZc+KptFOWFSI9w==}
     engines: {node: '>=18'}
 
+  slice-ansi@8.0.0:
+    resolution: {integrity: sha512-stxByr12oeeOyY2BlviTNQlYV5xOj47GirPr4yA1hE9JCtxfQN0+tVbkxwCtYDQWhEKWFHsEK48ORg5jrouCAg==}
+    engines: {node: '>=20'}
+
   smart-buffer@4.2.0:
     resolution: {integrity: sha512-94hK0Hh8rPqQl2xXc3HsaBoOXKV20MToPkcXvwbISWLEs+64sBq5kFgn2kJDHb1Pry9yrP0dxrCI9RRci7RXKg==}
     engines: {node: '>= 6.0.0', npm: '>= 3.0.0'}
@@ -6146,6 +6170,10 @@ packages:
   streamx@2.22.0:
     resolution: {integrity: sha512-sLh1evHOzBy/iWRiR6d1zRcLao4gGZr3C1kzNz4fopCOKJb6xD9ub8Mpi9Mr1R6id5o43S+d93fI48UC5uM9aw==}
 
+  string-argv@0.3.2:
+    resolution: {integrity: sha512-aqD2Q0144Z+/RqG52NeHEkZauTAUWJO8c6yTftGJKO3Tja5tUgIfmIl6kExvhtxSDP7fXB6DvzkfMpCd/F3G+Q==}
+    engines: {node: '>=0.6.19'}
+
   string-width@2.1.1:
     resolution: {integrity: sha512-nOqH59deCq9SRHlxq1Aw85Jnt4w6KvLKqWVik6oA9ZklXLNIOlqg4F2yrT1MVaTjAqvVwdfeZ7w7aCvJD7ugkw==}
     engines: {node: '>=4'}
@@ -6166,6 +6194,10 @@ packages:
     resolution: {integrity: sha512-Kxl3KJGb/gxkaUMOjRsQ8IrXiGW75O4E3RPjFIINOVH8AMl2SQ/yWdTzWwF3FevIX9LcMAjJW+GRwAlAbTSXdg==}
     engines: {node: '>=20'}
 
+  string-width@8.2.1:
+    resolution: {integrity: sha512-IIaP0g3iy9Cyy18w3M9YcaDudujEAVHKt3a3QJg1+sr/oX96TbaGUubG0hJyCjCBThFH+tFpcIyoUHUn1ogaLA==}
+    engines: {node: '>=20'}
+
   string_decoder@1.1.1:
     resolution: {integrity: sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==}
 
@@ -6318,6 +6350,10 @@ packages:
     resolution: {integrity: sha512-dAqSqE/RabpBKI8+h26GfLq6Vb3JVXs30XYQjdMjaj/c2tS8IYYMbIzP599KtRj7c57/wYApb3QjgRgXmrCukA==}
     engines: {node: '>=18'}
 
+  tinyexec@1.2.4:
+    resolution: {integrity: sha512-SHf/r48b7vOrjve9PxJo3MN5v5yuyjHvdUcrQffT3WXMUfnGmHDVbC4k3sHJaJTgZCwpUplIaAo5ANtMyp3YHg==}
+    engines: {node: '>=18'}
+
   tinyglobby@0.2.15:
     resolution: {integrity: sha512-j2Zq4NyQYG5XMST4cbs02Ak8iJUdxRM0XI5QyxXuZOzKOINmWurp3smXu3y5wDcJrptwpSjgXHzIQxR0omXljQ==}
     engines: {node: '>=12.0.0'}
@@ -6937,6 +6973,10 @@ packages:
     resolution: {integrity: sha512-1tMA907+V4QmxV7dbRvb4/8MaRALK6q9Abid3ndMYnbyo8piisCmeONVqVSXqQA3KaP4SLt5b7ud6E2sqP8TFw==}
     engines: {node: '>=0.4.0'}
 
+  wrap-ansi@10.0.0:
+    resolution: {integrity: sha512-SGcvg80f0wUy2/fXES19feHMz8E0JoXv2uNgHOu4Dgi2OrCy1lqwFYEJz1BLbDI0exjPMe/ZdzZ/YpGECBG/aQ==}
+    engines: {node: '>=20'}
+
   wrap-ansi@6.2.0:
     resolution: {integrity: sha512-r6lPcBGxZXlIcymEu7InxDMhdW0KDxpLgoFLcguasxCaJ/SOIZwINatK9KY/tf+ZrlywOKU0UDj3ATXUBfxJXA==}
     engines: {node: '>=8'}
@@ -7015,11 +7055,6 @@ packages:
     resolution: {integrity: sha512-YgvUTfwqyc7UXVMrB+SImsVYSmTS8X/tSrtdNZMImM+n7+QTriRXyXim0mBrTXNeqzVF0KWGgHPeiyViFFrNDw==}
     engines: {node: '>=18'}
 
-  yaml@2.8.2:
-    resolution: {integrity: sha512-mplynKqc1C2hTVYxd0PU2xQAc22TI1vShAYGksCCfxbn/dFwnHTNi1bvYsBTkhdUNtGIf5xNOg938rrSSYvS9A==}
-    engines: {node: '>= 14.6'}
-    hasBin: true
-
   yaml@2.9.0:
     resolution: {integrity: sha512-2AvhNX3mb8zd6Zy7INTtSpl1F15HW6Wnqj0srWlkKLcpYl/gMIMJiyuGq2KeI2YFxUPjdlB+3Lc10seMLtL4cA==}
     engines: {node: '>= 14.6'}
@@ -7113,12 +7148,12 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  '@astrojs/mdx@5.0.4(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2))':
+  '@astrojs/mdx@5.0.4(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0))':
     dependencies:
       '@astrojs/markdown-remark': 7.1.1
       '@mdx-js/mdx': 3.1.1
       acorn: 8.16.0
-      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2)
+      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0)
       es-module-lexer: 2.1.0
       estree-util-visit: 2.0.0
       hast-util-to-html: 9.0.5
@@ -7142,17 +7177,17 @@ snapshots:
       stream-replace-string: 2.0.0
       zod: 4.4.3
 
-  '@astrojs/starlight@0.39.1(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2))(typescript@5.9.3)':
+  '@astrojs/starlight@0.39.1(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0))(typescript@5.9.3)':
     dependencies:
       '@astrojs/markdown-remark': 7.1.1
-      '@astrojs/mdx': 5.0.4(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2))
+      '@astrojs/mdx': 5.0.4(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0))
       '@astrojs/sitemap': 3.7.2
       '@pagefind/default-ui': 1.5.2
       '@types/hast': 3.0.4
       '@types/js-yaml': 4.0.9
       '@types/mdast': 4.0.4
-      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2)
+      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0)
-      astro-expressive-code: 0.42.0(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2))
+      astro-expressive-code: 0.42.0(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0))
       bcp-47: 2.1.0
       hast-util-from-html: 2.0.3
       hast-util-select: 6.0.4
@@ -7934,7 +7969,7 @@ snapshots:
       minimatch: 9.0.5
       read-pkg: 9.0.1
       semver: 7.7.2
-      yaml: 2.8.2
+      yaml: 2.9.0
       yargs: 17.7.2
 
   '@netlify/build@35.5.10(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(picomatch@4.0.3)(rollup@4.60.3)':
@@ -7988,7 +8023,7 @@ snapshots:
       ts-node: 10.9.2(@types/node@25.0.10)(typescript@5.9.3)
       typescript: 5.9.3
       uuid: 11.1.0
-      yaml: 2.8.2
+      yaml: 2.9.0
       yargs: 17.7.2
       zod: 3.25.76
     transitivePeerDependencies:
@@ -8033,7 +8068,7 @@ snapshots:
       read-package-up: 11.0.0
       tomlify-j0.4: 3.0.0
       validate-npm-package-name: 5.0.1
-      yaml: 2.8.2
+      yaml: 2.9.0
       yargs: 17.7.2
       zod: 4.3.6
 
@@ -8602,7 +8637,7 @@ snapshots:
     dependencies:
       '@types/estree': 1.0.8
       estree-walker: 2.0.2
-      picomatch: 4.0.3
+      picomatch: 4.0.4
     optionalDependencies:
       rollup: 4.60.3
 
@@ -9034,29 +9069,29 @@ snapshots:
       - rollup
       - supports-color
 
-  '@vitest/browser-playwright@4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)':
+  '@vitest/browser-playwright@4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)':
     dependencies:
-      '@vitest/browser': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)
+      '@vitest/browser': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)
-      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))
+      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))
       playwright: 1.61.1
       tinyrainbow: 3.0.3
-      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
     transitivePeerDependencies:
       - bufferutil
       - msw
       - utf-8-validate
       - vite
 
-  '@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)':
+  '@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)':
     dependencies:
-      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))
+      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))
       '@vitest/utils': 4.0.18
       magic-string: 0.30.21
       pixelmatch: 7.1.0
       pngjs: 7.0.0
       sirv: 3.0.2
       tinyrainbow: 3.0.3
-      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
       ws: 8.19.0
     transitivePeerDependencies:
       - bufferutil
@@ -9064,7 +9099,7 @@ snapshots:
       - utf-8-validate
       - vite
 
-  '@vitest/coverage-v8@4.0.18(@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18))(vitest@4.0.18)':
+  '@vitest/coverage-v8@4.0.18(@vitest/browser@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18))(vitest@4.0.18)':
     dependencies:
       '@bcoe/v8-coverage': 1.0.2
       '@vitest/utils': 4.0.18
@@ -9076,9 +9111,9 @@ snapshots:
       obug: 2.1.1
       std-env: 3.10.0
       tinyrainbow: 3.0.3
-      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vitest: 4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
     optionalDependencies:
-      '@vitest/browser': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)
+      '@vitest/browser': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)
 
   '@vitest/expect@4.0.18':
     dependencies:
@@ -9089,13 +9124,13 @@ snapshots:
       chai: 6.2.2
       tinyrainbow: 3.0.3
 
-  '@vitest/mocker@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))':
+  '@vitest/mocker@4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))':
     dependencies:
       '@vitest/spy': 4.0.18
       estree-walker: 3.0.3
       magic-string: 0.30.21
     optionalDependencies:
-      vite: 7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vite: 7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
 
   '@vitest/pretty-format@4.0.18':
     dependencies:
@@ -9421,12 +9456,12 @@ snapshots:
 
   astring@1.9.0: {}
 
-  astro-expressive-code@0.42.0(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2)):
+  astro-expressive-code@0.42.0(astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0)):
     dependencies:
-      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2)
+      astro: 6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0)
       rehype-expressive-code: 0.42.0
 
-  astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.8.2):
+  astro@6.3.1(@netlify/blobs@10.5.0)(@types/node@25.0.10)(db0@0.3.1)(ioredis@5.6.0)(jiti@2.6.1)(rollup@4.60.3)(terser@5.39.0)(yaml@2.9.0):
     dependencies:
       '@astrojs/compiler': 4.0.0
       '@astrojs/internal-helpers': 0.9.0
@@ -9478,8 +9513,8 @@ snapshots:
       unist-util-visit: 5.1.0
       unstorage: 1.17.5(@netlify/blobs@10.5.0)(db0@0.3.1)(ioredis@5.6.0)
       vfile: 6.0.3
-      vite: 7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vite: 7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
-      vitefu: 1.1.3(vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))
+      vitefu: 1.1.3(vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))
       xxhash-wasm: 1.1.0
       yargs-parser: 22.0.0
       zod: 4.4.3
@@ -9839,6 +9874,11 @@ snapshots:
 
   cli-spinners@3.4.0: {}
 
+  cli-truncate@5.2.0:
+    dependencies:
+      slice-ansi: 8.0.0
+      string-width: 8.2.1
+
   cli-width@3.0.0: {}
 
   cli-width@4.1.0: {}
@@ -10923,6 +10963,8 @@ snapshots:
 
   get-east-asian-width@1.4.0: {}
 
+  get-east-asian-width@1.6.0: {}
+
   get-intrinsic@1.3.0:
     dependencies:
       call-bind-apply-helpers: 1.0.2
@@ -11836,6 +11878,15 @@ snapshots:
 
   lilconfig@3.1.3: {}
 
+  lint-staged@17.0.8:
+    dependencies:
+      listr2: 10.2.2
+      picomatch: 4.0.4
+      string-argv: 0.3.2
+      tinyexec: 1.2.4
+    optionalDependencies:
+      yaml: 2.9.0
+
   listhen@1.9.0:
     dependencies:
       '@parcel/watcher': 2.5.6
@@ -11857,6 +11908,14 @@ snapshots:
       untun: 0.1.3
       uqr: 0.1.2
 
+  listr2@10.2.2:
+    dependencies:
+      cli-truncate: 5.2.0
+      eventemitter3: 5.0.4
+      log-update: 6.1.0
+      rfdc: 1.4.1
+      wrap-ansi: 10.0.0
+
   locate-path@6.0.0:
     dependencies:
       p-locate: 5.0.0
@@ -14073,6 +14132,11 @@ snapshots:
       ansi-styles: 6.2.3
       is-fullwidth-code-point: 5.1.0
 
+  slice-ansi@8.0.0:
+    dependencies:
+      ansi-styles: 6.2.3
+      is-fullwidth-code-point: 5.1.0
+
   smart-buffer@4.2.0: {}
 
   smol-toml@1.6.1: {}
@@ -14181,6 +14245,8 @@ snapshots:
     optionalDependencies:
       bare-events: 2.5.4
 
+  string-argv@0.3.2: {}
+
   string-width@2.1.1:
     dependencies:
       is-fullwidth-code-point: 2.0.0
@@ -14209,6 +14275,11 @@ snapshots:
       get-east-asian-width: 1.4.0
       strip-ansi: 7.1.2
 
+  string-width@8.2.1:
+    dependencies:
+      get-east-asian-width: 1.6.0
+      strip-ansi: 7.1.2
+
   string_decoder@1.1.1:
     dependencies:
       safe-buffer: 5.1.2
@@ -14367,6 +14438,8 @@ snapshots:
 
   tinyexec@1.1.2: {}
 
+  tinyexec@1.2.4: {}
+
   tinyglobby@0.2.15:
     dependencies:
       fdir: 6.5.0(picomatch@4.0.3)
@@ -14695,11 +14768,11 @@ snapshots:
       '@types/unist': 3.0.3
       vfile-message: 4.0.3
 
-  vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2):
+  vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0):
     dependencies:
       esbuild: 0.27.2
-      fdir: 6.5.0(picomatch@4.0.3)
+      fdir: 6.5.0(picomatch@4.0.4)
-      picomatch: 4.0.3
+      picomatch: 4.0.4
       postcss: 8.5.6
       rollup: 4.56.0
       tinyglobby: 0.2.15
@@ -14708,22 +14781,7 @@ snapshots:
       fsevents: 2.3.3
       jiti: 2.6.1
       terser: 5.39.0
-      yaml: 2.8.2
+      yaml: 2.9.0
-
-  vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2):
-    dependencies:
-      esbuild: 0.27.7
-      fdir: 6.5.0(picomatch@4.0.4)
-      picomatch: 4.0.4
-      postcss: 8.5.14
-      rollup: 4.60.3
-      tinyglobby: 0.2.16
-    optionalDependencies:
-      '@types/node': 25.0.10
-      fsevents: 2.3.3
-      jiti: 2.6.1
-      terser: 5.39.0
-      yaml: 2.8.2
 
   vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0):
     dependencies:
@@ -14740,14 +14798,14 @@ snapshots:
       terser: 5.39.0
       yaml: 2.9.0
 
-  vitefu@1.1.3(vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)):
+  vitefu@1.1.3(vite@7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)):
     optionalDependencies:
-      vite: 7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vite: 7.3.3(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
 
-  vitest@4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2):
+  vitest@4.0.18(@opentelemetry/api@1.8.0)(@types/node@25.0.10)(@vitest/browser-playwright@4.0.18)(happy-dom@20.3.7)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0):
     dependencies:
       '@vitest/expect': 4.0.18
-      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))
+      '@vitest/mocker': 4.0.18(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))
       '@vitest/pretty-format': 4.0.18
       '@vitest/runner': 4.0.18
       '@vitest/snapshot': 4.0.18
@@ -14764,12 +14822,12 @@ snapshots:
       tinyexec: 1.0.2
       tinyglobby: 0.2.15
       tinyrainbow: 3.0.3
-      vite: 7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2)
+      vite: 7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0)
       why-is-node-running: 2.3.0
     optionalDependencies:
       '@opentelemetry/api': 1.8.0
       '@types/node': 25.0.10
-      '@vitest/browser-playwright': 4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.8.2))(vitest@4.0.18)
+      '@vitest/browser-playwright': 4.0.18(playwright@1.61.1)(vite@7.3.1(@types/node@25.0.10)(jiti@2.6.1)(terser@5.39.0)(yaml@2.9.0))(vitest@4.0.18)
       happy-dom: 20.3.7
     transitivePeerDependencies:
       - jiti
@@ -14862,6 +14920,12 @@ snapshots:
 
   wordwrap@0.0.3: {}
 
+  wrap-ansi@10.0.0:
+    dependencies:
+      ansi-styles: 6.2.3
+      string-width: 8.2.1
+      strip-ansi: 7.1.2
+
   wrap-ansi@6.2.0:
     dependencies:
       ansi-styles: 4.3.0
@@ -14918,8 +14982,6 @@ snapshots:
 
   yallist@5.0.0: {}
 
-  yaml@2.8.2: {}
-
   yaml@2.9.0: {}
 
   yargs-parser@21.1.1: {}

test/e2e/README.md

@@ -1,24 +1,45 @@
 # End-to-end example tests
 
-These specs load each `demo/examples/*` component into a **real browser** (Chromium
+These specs load each `demo/examples/*` component into a **real browser**
-via Playwright) and drive it the way a user would. They exist because the v5
+(Chromium, Firefox, and WebKit via Playwright) and drive it the way a user
-correctness work targets behaviors that happy-dom cannot reproduce — custom
+would. They exist because the v5 correctness work targets behaviors that
-element upgrade ordering, the constructor-attribute rule, empty-string/removed
+happy-dom cannot reproduce — custom element upgrade ordering, the
-attributes, and adopted stylesheets — so the unit suite alone can pass while a
+constructor-attribute rule, empty-string/removed attributes, and adopted
-real browser misbehaves.
+stylesheets — so the unit suite alone can pass while a real browser misbehaves.
+Running across engines also catches cross-browser differences.
 
 ## Running
 
 ```sh
-pnpm test:e2e     # browser specs only (this folder)
+pnpm test:e2e           # default: Chromium only (fast, universal)
+pnpm test:e2e:chromium  # Chromium
+pnpm test:e2e:firefox   # Firefox
+pnpm test:e2e:webkit    # WebKit (the engine behind Safari)
+pnpm test:e2e:all       # Chromium + Firefox + WebKit
+
 pnpm test               # fast unit suite (happy-dom), unchanged
-pnpm test:all     # both
+pnpm test:all           # unit + default e2e
 ```
 
+`pnpm test:e2e` stays on Chromium so it works everywhere with minimal setup; use
+`test:e2e:all` (or a CI matrix) for the full cross-browser run. Each script just
+sets the `E2E_BROWSERS` env var (comma-separated), which the config reads.
+
 Config lives in `vitest.e2e.config.mjs` (Vitest browser mode + the
-`@vitest/browser-playwright` provider). It is kept separate from
+`@vitest/browser-playwright` provider), kept separate from `vitest.config.mjs`
-`vitest.config.mjs` so `pnpm test` stays fast and needs no browser. The
+so `pnpm test` stays fast and needs no browser.
-Chromium binary is installed with `npx playwright install chromium`.
+
+### Browser setup
+
+```sh
+npx playwright install chromium firefox webkit   # download the browsers
+npx playwright install-deps                       # Linux only: system libraries
+```
+
+Firefox and especially WebKit need extra OS libraries on Linux (`libwoff1`,
+etc.); `playwright install-deps` requires root. Without them those engines fail
+to launch — which is why the default target is Chromium and CI installs the deps
+before running `test:e2e:all`.
 
 ## Coverage
 

vitest.e2e.config.mjs

@@ -4,11 +4,21 @@ import { fileURLToPath } from 'node:url'
 
 const src = (p) => fileURLToPath(new URL(`./src/${p}`, import.meta.url))
 
-// End-to-end specs run against the real `src/` in a real browser (Chromium via
+// Which engines to run the e2e suite against. Defaults to all three Playwright
+// engines (Chromium, Firefox, and WebKit — the engine behind Safari). Override
+// with e.g. `E2E_BROWSERS=chromium pnpm test:e2e` in environments that only
+// have some browsers installed (Firefox/WebKit also need system libs — see
+// `npx playwright install-deps`).
+const BROWSERS = (process.env.E2E_BROWSERS || 'chromium,firefox,webkit')
+  .split(',')
+  .map((name) => name.trim())
+  .filter(Boolean)
+
+// End-to-end specs run against the real `src/` in a real browser (via
 // Playwright), so behaviors that happy-dom cannot reproduce — custom-element
 // upgrade ordering, constructor attribute rules, adopted stylesheets — are
-// actually exercised. Kept separate from the unit config so `pnpm test` stays
+// actually exercised across engines. Kept separate from the unit config so
-// fast and headless-browser-free.
+// `pnpm test` stays fast and headless-browser-free.
 export default defineConfig({
   // The demo examples import the `web-component-base` package; resolve it to
   // local source (mirrors demo/vite.config.js) so e2e tests exercise src.
@@ -29,7 +39,7 @@ export default defineConfig({
       provider: playwright(),
       headless: true,
       screenshotFailures: false,
-      instances: [{ browser: 'chromium' }],
+      instances: BROWSERS.map((browser) => ({ browser })),
     },
   },
 })