When updating web element APIs, add targeted Playwright tests in packages/web-platform/web-elements/tests/web-elements.spec.ts and keep changes minimal. Ensure Playwright browsers are installed (pnpm exec playwright install --with-deps ) before running web-elements tests. For x-input type="number" in web-elements, keep inner input type as text, set inputmode="decimal", and filter number input internally without setting input-filter explicitly. Add new web-elements UI fixtures under packages/web-platform/web-elements/tests/fixtures and commit matching snapshots in packages/web-platform/web-elements/tests/web-elements.spec.ts-snapshots.

When changing initial CSS handling in template-webpack-plugin, add or update a code-splitting case that asserts the exact selector order in tasm.json, not just that CSS assets exist. Prefer a shared-plus-split initial chunk fixture when validating CSS merge order so the expected rule sequence follows the source import order clearly.

For Playwright-related CI jobs, add ulimit -Sn 655350 directly in each job's run block before invoking Playwright commands.

For ReactLynx Playwright coverage in web-core-e2e, add fixtures under tests/reactlynx/<test-title>/index.jsx and use the same <test-title> string in tests/reactlynx.spec.ts. Skip WebKit for tests that depend on page.mouse.wheel, since the existing suites treat WebKit wheel support as unavailable.