test(instant-validation): it.failing fixture for usePathname misclassification

test/e2e/app-dir/instant-validation/app/default/invalid-use-pathname-no-samples/[slug]/page.tsx

@@ -0,0 +1,9 @@
+import { PathnameLabel } from './pathname-label'
+
+export default function Page() {
+  return (
+    <main>
+      <PathnameLabel />
+    </main>
+  )
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-pathname-no-samples/[slug]/pathname-label.tsx

@@ -0,0 +1,8 @@
+'use client'
+
+import { usePathname } from 'next/navigation'
+
+export function PathnameLabel() {
+  const pathname = usePathname()
+  return <span data-testid="pathname-label">{pathname}</span>
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segment-no-samples/[slug]/active-tab.tsx

@@ -0,0 +1,8 @@
+'use client'
+
+import { useSelectedLayoutSegment } from 'next/navigation'
+
+export function ActiveTab() {
+  const segment = useSelectedLayoutSegment()
+  return <span data-testid="active-tab">{segment}</span>
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segment-no-samples/[slug]/layout.tsx

@@ -0,0 +1,10 @@
+import { ActiveTab } from './active-tab'
+
+export default function Layout({ children }: { children: React.ReactNode }) {
+  return (
+    <div>
+      <ActiveTab />
+      {children}
+    </div>
+  )
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segment-no-samples/[slug]/page.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <main>Leaf page</main>
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segments-no-samples/[slug]/breadcrumb-trail.tsx

@@ -0,0 +1,8 @@
+'use client'
+
+import { useSelectedLayoutSegments } from 'next/navigation'
+
+export function BreadcrumbTrail() {
+  const segments = useSelectedLayoutSegments()
+  return <span data-testid="breadcrumb-trail">{segments.join('/')}</span>
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segments-no-samples/[slug]/layout.tsx

@@ -0,0 +1,10 @@
+import { BreadcrumbTrail } from './breadcrumb-trail'
+
+export default function Layout({ children }: { children: React.ReactNode }) {
+  return (
+    <div>
+      <BreadcrumbTrail />
+      {children}
+    </div>
+  )
+}

test/e2e/app-dir/instant-validation/app/default/invalid-use-selected-layout-segments-no-samples/[slug]/page.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <main>Leaf page</main>
+}

test/e2e/app-dir/instant-validation/app/default/page.tsx

@@ -14,6 +14,15 @@ export default async function Page() {
         <li>
           <DebugLinks href="/default/static/valid-blocking-inside-static" />
         </li>
+        <li>
+          <DebugLinks href="/default/invalid-use-pathname-no-samples/123" />
+        </li>
+        <li>
+          <DebugLinks href="/default/invalid-use-selected-layout-segment-no-samples/123" />
+        </li>
+        <li>
+          <DebugLinks href="/default/invalid-use-selected-layout-segments-no-samples/123" />
+        </li>
       </ul>
     </main>
   )

test/e2e/app-dir/instant-validation/instant-validation.test.ts

@@ -6,6 +6,7 @@ import {
   waitForValidation,
 } from 'e2e-utils/instant-validation'
 import {
+  getRedboxSource,
   openRedbox,
   retry,
   waitForNoErrorToast,
@@ -1893,6 +1894,48 @@ describe('instant validation', () => {
           expectNoBuildValidationErrors(result)
         }
       })
+
+      // usePathname is misclassified as "uncached data" today and the dev
+      // overlay attributes the error to the parent's JSX line. This test
+      // asserts the correct stack attribution. When the URL-hook factory
+      // lands, `it.failing` will itself fail — flip to `it`.
+      /* eslint-disable jest/no-standalone-expect */
+      ;(isNextDev && !isClientNav ? it.failing : it)(
+        'invalid - usePathname() in a client component on a route with a fallback param',
+        async () => {
+          if (!isNextDev || isClientNav) return
+          const browser = await navigateTo(
+            '/default/invalid-use-pathname-no-samples/123'
+          )
+          await openRedbox(browser)
+          const source = await getRedboxSource(browser)
+          expect(source).toContain('pathname-label.tsx')
+          expect(source).toContain('PathnameLabel')
+        }
+      )
+
+      it('invalid - useSelectedLayoutSegment() in a layout on a route with a fallback param', async () => {
+        if (!isNextDev || isClientNav) return
+        const browser = await navigateTo(
+          '/default/invalid-use-selected-layout-segment-no-samples/123'
+        )
+        await openRedbox(browser)
+        const source = await getRedboxSource(browser)
+        expect(source).toContain('active-tab.tsx')
+        expect(source).toContain('ActiveTab')
+      })
+
+      it('invalid - useSelectedLayoutSegments() in a layout on a route with a fallback param', async () => {
+        if (!isNextDev || isClientNav) return
+        const browser = await navigateTo(
+          '/default/invalid-use-selected-layout-segments-no-samples/123'
+        )
+        await openRedbox(browser)
+        const source = await getRedboxSource(browser)
+        expect(source).toContain('breadcrumb-trail.tsx')
+        expect(source).toContain('BreadcrumbTrail')
+      })
+      /* eslint-enable jest/no-standalone-expect */
     })
 
     describe('client errors', () => {