From 04711e57140bd8481814f16b7f51c3a57bacea94 Mon Sep 17 00:00:00 2001
From: daishi <daishi@axlight.com>
Date: Fri, 27 Feb 2026 19:42:09 +0900
Subject: [PATCH 1/3] add failing test with createPortal

---
 e2e/fixtures/use-router/src/TestRouter.tsx | 12 ++++++
 e2e/use-router.spec.ts                     | 43 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/e2e/fixtures/use-router/src/TestRouter.tsx b/e2e/fixtures/use-router/src/TestRouter.tsx
index f5516e5d3b..2799887876 100644
--- a/e2e/fixtures/use-router/src/TestRouter.tsx
+++ b/e2e/fixtures/use-router/src/TestRouter.tsx
@@ -1,17 +1,29 @@
 'use client';
 
+import { createPortal } from 'react-dom';
 import { Link, useRouter } from 'waku';
 
+const BodyPortal = () => {
+  return createPortal(<div data-testid="portal-marker">portal</div>, document.body);
+};
+
 export default function TestRouter() {
   const router = useRouter();
   const params = new URLSearchParams(router.query);
   const queryCount = parseInt(params.get('count') || '0');
   const hashCount = parseInt(router.hash?.slice(1) || '0');
+  const portal = params.get('portal') === '1';
   return (
     <>
+      {portal && <BodyPortal />}
       <p data-testid="path">Path: {router.path}</p>
       <p data-testid="query">Query: {queryCount}</p>
       <p data-testid="hash">Hash: {hashCount}</p>
+      <p>
+        <Link data-testid="go-dynamic-portal" to="/dynamic?portal=1">
+          Go to dynamic portal
+        </Link>
+      </p>
       <p>
         <Link to={`?count=${queryCount + 1}`}>Increment query</Link>
       </p>
diff --git a/e2e/use-router.spec.ts b/e2e/use-router.spec.ts
index 3183967202..98d1536284 100644
--- a/e2e/use-router.spec.ts
+++ b/e2e/use-router.spec.ts
@@ -112,6 +112,49 @@ test.describe('useRouter', () => {
       await expect(page.getByTestId('query')).toHaveText('Query: 0');
     });
 
+    test('browser back/forward with portal page has no runtime errors', async ({
+      page,
+    }) => {
+      const runtimeErrors: string[] = [];
+      let delayedRequestCount = 0;
+      page.on('pageerror', (error) => {
+        runtimeErrors.push(error.message);
+      });
+      page.on('console', (msg) => {
+        if (msg.type() === 'error' && msg.text().includes('removeChild')) {
+          runtimeErrors.push(msg.text());
+        }
+      });
+      await page.route('**/RSC/R/dynamic.txt**', async (route) => {
+        if (route.request().url().includes('query=portal%3D1')) {
+          delayedRequestCount += 1;
+          await new Promise((resolve) => setTimeout(resolve, 200));
+        }
+        await route.continue();
+      });
+
+      await page.goto(`http://localhost:${port}/static`);
+      await waitForHydration(page);
+      await page.click('text=Increment query (push)');
+      await expect(page.getByTestId('query')).toHaveText('Query: 1');
+
+      await page.getByTestId('go-dynamic-portal').click();
+      await expect(page.getByRole('heading', { name: 'Dynamic' })).toBeVisible();
+      await expect(page.getByTestId('portal-marker')).toBeVisible();
+      await page.evaluate(() => {
+        window.history.back();
+        window.history.forward();
+        window.history.back();
+      });
+
+      expect(delayedRequestCount).toBeGreaterThan(0);
+      expect(runtimeErrors).toEqual([]);
+      await expect.poll(() => new URL(page.url()).pathname).toBe('/static');
+      await expect
+        .poll(() => new URL(page.url()).searchParams.get('count'))
+        .toBe('1');
+    });
+
     test('router.reload refetches dynamic route', async ({ page }) => {
       await page.goto(`http://localhost:${port}/dynamic`);
       await waitForHydration(page);

From 0bb2380bb40bdc614f5cbda215485cc1648f2d09 Mon Sep 17 00:00:00 2001
From: daishi <daishi@axlight.com>
Date: Fri, 27 Feb 2026 19:47:48 +0900
Subject: [PATCH 2/3] move test

---
 .../src/components/route-state.tsx            |  7 +++
 .../router-client/src/pages/start.tsx         |  5 +++
 e2e/fixtures/use-router/src/TestRouter.tsx    | 12 -----
 e2e/router-client.spec.ts                     | 44 +++++++++++++++++++
 e2e/use-router.spec.ts                        | 43 ------------------
 5 files changed, 56 insertions(+), 55 deletions(-)

diff --git a/e2e/fixtures/router-client/src/components/route-state.tsx b/e2e/fixtures/router-client/src/components/route-state.tsx
index e213d42253..3a03492a35 100644
--- a/e2e/fixtures/router-client/src/components/route-state.tsx
+++ b/e2e/fixtures/router-client/src/components/route-state.tsx
@@ -1,11 +1,18 @@
 'use client';
 
+import { createPortal } from 'react-dom';
 import { useRouter } from 'waku';
 
 export function RouteState() {
   const router = useRouter();
+  const portal = new URLSearchParams(router.query).get('portal') === '1';
   return (
     <>
+      {portal &&
+        createPortal(
+          <div data-testid="portal-marker">portal</div>,
+          document.body,
+        )}
       <p data-testid="route-path">{router.path}</p>
       <p data-testid="route-query">{router.query}</p>
       <p data-testid="route-hash">{router.hash}</p>
diff --git a/e2e/fixtures/router-client/src/pages/start.tsx b/e2e/fixtures/router-client/src/pages/start.tsx
index 29d85da013..b97dda429e 100644
--- a/e2e/fixtures/router-client/src/pages/start.tsx
+++ b/e2e/fixtures/router-client/src/pages/start.tsx
@@ -11,6 +11,11 @@ export default function StartPage() {
           Go next
         </Link>
       </p>
+      <p>
+        <Link to="/next?portal=1" data-testid="go-next-portal">
+          Go next portal
+        </Link>
+      </p>
       <p>
         <Link to="/start?from=query-only" data-testid="go-query-only">
           Go query only
diff --git a/e2e/fixtures/use-router/src/TestRouter.tsx b/e2e/fixtures/use-router/src/TestRouter.tsx
index 2799887876..f5516e5d3b 100644
--- a/e2e/fixtures/use-router/src/TestRouter.tsx
+++ b/e2e/fixtures/use-router/src/TestRouter.tsx
@@ -1,29 +1,17 @@
 'use client';
 
-import { createPortal } from 'react-dom';
 import { Link, useRouter } from 'waku';
 
-const BodyPortal = () => {
-  return createPortal(<div data-testid="portal-marker">portal</div>, document.body);
-};
-
 export default function TestRouter() {
   const router = useRouter();
   const params = new URLSearchParams(router.query);
   const queryCount = parseInt(params.get('count') || '0');
   const hashCount = parseInt(router.hash?.slice(1) || '0');
-  const portal = params.get('portal') === '1';
   return (
     <>
-      {portal && <BodyPortal />}
       <p data-testid="path">Path: {router.path}</p>
       <p data-testid="query">Query: {queryCount}</p>
       <p data-testid="hash">Hash: {hashCount}</p>
-      <p>
-        <Link data-testid="go-dynamic-portal" to="/dynamic?portal=1">
-          Go to dynamic portal
-        </Link>
-      </p>
       <p>
         <Link to={`?count=${queryCount + 1}`}>Increment query</Link>
       </p>
diff --git a/e2e/router-client.spec.ts b/e2e/router-client.spec.ts
index 279e4c9caa..a4cb0f3a02 100644
--- a/e2e/router-client.spec.ts
+++ b/e2e/router-client.spec.ts
@@ -249,6 +249,50 @@ test.describe('router-client', () => {
     expect(await getScrollToCalls(page)).toHaveLength(0);
   });
 
+  test('portal route with popstate churn preserves prior query history entry', async ({
+    page,
+  }) => {
+    const runtimeErrors: string[] = [];
+    let delayedRequestCount = 0;
+    page.on('pageerror', (error) => {
+      runtimeErrors.push(error.message);
+    });
+    page.on('console', (msg) => {
+      if (msg.type() === 'error' && msg.text().includes('removeChild')) {
+        runtimeErrors.push(msg.text());
+      }
+    });
+    await page.route('**/RSC/R/next.txt**', async (route) => {
+      if (route.request().url().includes('query=portal%3D1')) {
+        delayedRequestCount += 1;
+        await new Promise((resolve) => setTimeout(resolve, 200));
+      }
+      await route.continue();
+    });
+
+    await page.goto(`http://localhost:${port}/start`);
+    await waitForHydration(page);
+
+    await page.getByTestId('router-push-query-only').click();
+    await expect(page.getByTestId('route-path')).toHaveText('/start');
+    await expect(page.getByTestId('route-query')).toHaveText('from=query-only');
+
+    await page.getByTestId('go-next-portal').click();
+    await expect(page.getByRole('heading', { name: 'Next' })).toBeVisible();
+    await expect(page.getByTestId('portal-marker')).toBeVisible();
+
+    await page.evaluate(() => {
+      window.history.back();
+      window.history.forward();
+      window.history.back();
+    });
+
+    expect(delayedRequestCount).toBeGreaterThan(0);
+    expect(runtimeErrors).toEqual([]);
+    await expect(page.getByTestId('route-path')).toHaveText('/start');
+    await expect(page.getByTestId('route-query')).toHaveText('from=query-only');
+  });
+
   test('back/forward for path-change history scrolls to top', async ({
     page,
   }) => {
diff --git a/e2e/use-router.spec.ts b/e2e/use-router.spec.ts
index 98d1536284..3183967202 100644
--- a/e2e/use-router.spec.ts
+++ b/e2e/use-router.spec.ts
@@ -112,49 +112,6 @@ test.describe('useRouter', () => {
       await expect(page.getByTestId('query')).toHaveText('Query: 0');
     });
 
-    test('browser back/forward with portal page has no runtime errors', async ({
-      page,
-    }) => {
-      const runtimeErrors: string[] = [];
-      let delayedRequestCount = 0;
-      page.on('pageerror', (error) => {
-        runtimeErrors.push(error.message);
-      });
-      page.on('console', (msg) => {
-        if (msg.type() === 'error' && msg.text().includes('removeChild')) {
-          runtimeErrors.push(msg.text());
-        }
-      });
-      await page.route('**/RSC/R/dynamic.txt**', async (route) => {
-        if (route.request().url().includes('query=portal%3D1')) {
-          delayedRequestCount += 1;
-          await new Promise((resolve) => setTimeout(resolve, 200));
-        }
-        await route.continue();
-      });
-
-      await page.goto(`http://localhost:${port}/static`);
-      await waitForHydration(page);
-      await page.click('text=Increment query (push)');
-      await expect(page.getByTestId('query')).toHaveText('Query: 1');
-
-      await page.getByTestId('go-dynamic-portal').click();
-      await expect(page.getByRole('heading', { name: 'Dynamic' })).toBeVisible();
-      await expect(page.getByTestId('portal-marker')).toBeVisible();
-      await page.evaluate(() => {
-        window.history.back();
-        window.history.forward();
-        window.history.back();
-      });
-
-      expect(delayedRequestCount).toBeGreaterThan(0);
-      expect(runtimeErrors).toEqual([]);
-      await expect.poll(() => new URL(page.url()).pathname).toBe('/static');
-      await expect
-        .poll(() => new URL(page.url()).searchParams.get('count'))
-        .toBe('1');
-    });
-
     test('router.reload refetches dynamic route', async ({ page }) => {
       await page.goto(`http://localhost:${port}/dynamic`);
       await waitForHydration(page);

From f6f0b2306e3df2587fcd57a40cdbdb63a4dea44c Mon Sep 17 00:00:00 2001
From: daishi <daishi@axlight.com>
Date: Fri, 27 Feb 2026 20:05:56 +0900
Subject: [PATCH 3/3] add another test

---
 e2e/router-client.spec.ts | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/e2e/router-client.spec.ts b/e2e/router-client.spec.ts
index d9b787ea0e..9beb4e3618 100644
--- a/e2e/router-client.spec.ts
+++ b/e2e/router-client.spec.ts
@@ -293,6 +293,39 @@ test.describe('router-client', () => {
     await expect(page.getByTestId('route-query')).toHaveText('from=query-only');
   });
 
+  test('non-portal route with popstate churn preserves prior query history entry', async ({
+    page,
+  }) => {
+    let delayedRequestCount = 0;
+    await page.route('**/RSC/R/next.txt**', async (route) => {
+      if (route.request().url().includes('query=x%3D1')) {
+        delayedRequestCount += 1;
+        await new Promise((resolve) => setTimeout(resolve, 200));
+      }
+      await route.continue();
+    });
+
+    await page.goto(`http://localhost:${port}/start`);
+    await waitForHydration(page);
+
+    await page.getByTestId('router-push-query-only').click();
+    await expect(page.getByTestId('route-path')).toHaveText('/start');
+    await expect(page.getByTestId('route-query')).toHaveText('from=query-only');
+
+    await page.getByTestId('go-next').click();
+    await expect(page.getByRole('heading', { name: 'Next' })).toBeVisible();
+
+    await page.evaluate(() => {
+      window.history.back();
+      window.history.forward();
+      window.history.back();
+    });
+
+    expect(delayedRequestCount).toBeGreaterThan(0);
+    await expect(page.getByTestId('route-path')).toHaveText('/start');
+    await expect(page.getByTestId('route-query')).toHaveText('from=query-only');
+  });
+
   test('back/forward for path-change history scrolls to top', async ({
     page,
   }) => {