nextjs - 💡(How to fix) Fix Bug: `history.pushState` to a new URL reverts when route has a prefetched `<Link>` + `proxy.ts` cookie-based redirect

Link to the code that reproduces this issue

https://github.com/asanoop24/nextjs-pushstate-prefetch-revert-repro

To Reproduce

git clone https://github.com/asanoop24/nextjs-pushstate-prefetch-revert-repro
cd nextjs-pushstate-prefetch-revert-repro
pnpm install
pnpm build
pnpm start

1. Open http://localhost:3000.
2. Click any period button (e.g. 7d). This seeds the last-period cookie.
3. Click a different period button (e.g. 90d). The URL flashes to ?period=90d and immediately reverts back to ?period=7d.
4. The server-rendered <pre> block confirms the RSC tree is for the old URL.

Current vs. Expected behavior

Expected behavior

URL stays on the new value; RSC re-fetches for the new URL.

Actual behavior

URL reverts to the previous value within ~1 frame. RSC tree never reflects the click.

Provide environment information

Operating System:
  Platform: linux
Binaries:
  Node: 22.x
  pnpm: 9.x
Relevant Packages:
  next: 16.1.7
  react: 19.2.4
  react-dom: 19.2.4
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Middleware, Linking and Navigating, Runtime, Dynamic Routes

Which stage(s) are affected? (Select all that apply)

next start (local), Other (Deployed)

Additional context

Reproduction: https://github.com/asanoop24/nextjs-pushstate-prefetch-revert-repro

Summary

Calling history.pushState to navigate to a new URL on the same route appears to succeed (URL updates, RSC fetch fires) but then silently reverts to the previous URL — when the same page contains:

1. A <Link> whose href includes the URL state being changed (so Next prefetches it and caches a router entry keyed by the original URL).
2. A useEffect that writes the URL state to a cookie on every change.
3. A proxy.ts (formerly middleware.ts) that NextResponse.redirects when that URL parameter is absent, restoring it from the cookie.

Each piece in isolation is fine. Together they break history.pushState. Removing any one of the three fixes it.

Suspected cause

Next.js monkey-patches history.pushState. The patched implementation fires an ACTION_RESTORE (or similar) action that consults the router prefetch cache.

Each <Link href="/?view=a&period=7d"> populates the prefetch cache with an entry keyed by that URL. When the user clicks a filter and the pushState lands on /?view=a&period=90d, the prefetch-cache lookup appears to fuzzy-match the old prefetched entry and "restore" its URL — undoing the user's change.

The proxy.ts redirect + cookie write amplify the trigger. Removing the redirect (the proxy.ts returning NextResponse.next() always) fixes it; removing the cookie write fixes it; removing prefetch={false} on the <Link> fixes it.

Possibly related: #92187 (router-cache regression in 16.x).