Pages Router: `<Link>` / `router.push()` strip query string from href

[james-elicx]

This issue was created by an agent analysing CI failures from the Next.js Deploy Suite (vinext main vs Next.js v16.2.6, 2026-05-22).

Problem

When a Pages Router <Link href="/about?hello=world"> is rendered (or router.push('/about?hello=world') is called), vinext drops the ?hello=world from both the rendered href attribute and the resulting navigation URL. Affects ~6 trailing-slashes tests asserting the final URL retains the query.

Expected URL `/about?hello=world`, got `/about`

Estimated Impact

~6 test failures across the deploy suite.

Affected Test Suites

• test/e2e/trailing-slashes/without-trailing-slash.test.ts (6 failures)

Recommendation

1. Reproduce first in vinext's own test suite. Render <Link href="/about?hello=world"> and click it; assert location.search === '?hello=world'.

2. Preserve query in the Link href resolver and the router. When normalising href, do not strip the query string. Pass it through to the navigation API and ensure the trailing-slash rewrite step does not drop it.

3. Re-check after trailing-slash normalisation. This intersects with Trailing slash configuration not enforced #1332 — trailing-slash normalisation must preserve the query.