test: regression tests for inherited intercepting route slot deduplication

examples/app-router-playground/app/_internal/_data.ts

@@ -126,6 +126,12 @@ const demos = [
         name: 'Parallel Routes',
         description: 'Render multiple pages in the same layout',
       },
+      {
+        slug: 'intercepting-routes',
+        name: 'Intercepting Routes',
+        description:
+          'Open a detail route as a modal during navigation while preserving the shareable URL',
+      },
     ],
   },
   {

examples/app-router-playground/app/intercepting-routes/@modal/(.)photo/[id]/page.tsx

@@ -0,0 +1,73 @@
+import db from '#/lib/db';
+import { Boundary } from '#/ui/boundary';
+import { XMarkIcon } from '@heroicons/react/24/solid';
+import Image from 'next/image';
+import Link from 'next/link';
+import { notFound } from 'next/navigation';
+
+export default async function Page({
+  params,
+}: {
+  params: Promise<{ id: string }>;
+}) {
+  const { id } = await params;
+  const product = db.product.find({ where: { id } });
+  if (!product) {
+    notFound();
+  }
+
+  return (
+    <div className="pointer-events-none fixed inset-0 z-20 flex items-center justify-center bg-black/70 p-4 backdrop-blur-sm">
+      <Boundary
+        label="@modal/(.)photo/[id]/page.tsx"
+        color="cyan"
+        kind="solid"
+        animateRerendering={false}
+        className="pointer-events-auto flex w-full max-w-3xl flex-col gap-6 rounded-2xl bg-gray-950"
+      >
+        <div className="flex items-start justify-between gap-4">
+          <div className="flex flex-col gap-2">
+            <div className="text-sm uppercase tracking-[0.2em] text-cyan-300">
+              Intercepted in modal
+            </div>
+            <h2 className="text-2xl font-semibold text-white">{product.name}</h2>
+          </div>
+
+          <Link
+            href="/intercepting-routes"
+            className="rounded-full border border-gray-800 p-2 text-gray-400 hover:border-gray-700 hover:text-white"
+            aria-label="Close modal"
+          >
+            <XMarkIcon className="size-5" />
+          </Link>
+        </div>
+
+        <div className="grid gap-6 lg:grid-cols-[minmax(0,16rem)_1fr]">
+          <div className="overflow-hidden rounded-2xl bg-gray-900/60 p-6">
+            <Image
+              src={`/shop/${product.image}`}
+              alt={product.name}
+              width={320}
+              height={320}
+              className="mx-auto brightness-150"
+            />
+          </div>
+
+          <div className="flex flex-col gap-4">
+            <p className="text-sm leading-6 text-gray-400">
+              The browser URL is already pointing at the product detail page, but
+              the source gallery stays mounted underneath because the navigation
+              was intercepted by the parallel slot.
+            </p>
+            <div className="font-mono text-sm text-cyan-300">
+              {`$${product.price.toFixed(2)}`}
+            </div>
+            <div className="text-xs text-gray-500">
+              Refresh this URL to see the standalone detail page instead.
+            </div>
+          </div>
+        </div>
+      </Boundary>
+    </div>
+  );
+}

examples/app-router-playground/app/intercepting-routes/@modal/default.tsx

@@ -0,0 +1,3 @@
+export default function Default() {
+  return null;
+}

examples/app-router-playground/app/intercepting-routes/layout.tsx

@@ -0,0 +1,44 @@
+import db from '#/lib/db';
+import { Mdx } from '#/ui/codehike';
+import { Boundary } from '#/ui/boundary';
+import { type Metadata } from 'next';
+import React from 'react';
+import readme from './readme.mdx';
+
+export async function generateMetadata(): Promise<Metadata> {
+  const demo = db.demo.find({ where: { slug: 'intercepting-routes' } });
+
+  return {
+    title: demo.name,
+    openGraph: { title: demo.name, images: [`/api/og?title=${demo.name}`] },
+  };
+}
+
+export default function Layout({
+  children,
+  modal,
+}: {
+  children: React.ReactNode;
+  modal: React.ReactNode;
+}) {
+  return (
+    <>
+      <Boundary label="Demo" kind="solid" animateRerendering={false}>
+        <Mdx source={readme} collapsed={true} />
+      </Boundary>
+
+      <div className="relative flex flex-col gap-6">
+        <Boundary
+          label="layout.tsx"
+          kind="solid"
+          animateRerendering={false}
+          className="flex flex-col gap-6"
+        >
+          {children}
+        </Boundary>
+
+        {modal}
+      </div>
+    </>
+  );
+}

examples/app-router-playground/app/intercepting-routes/page.tsx

@@ -0,0 +1,33 @@
+import db from '#/lib/db';
+import { Boundary } from '#/ui/boundary';
+import { ProductCard, ProductList } from '#/ui/product-card';
+import Link from 'next/link';
+
+export default function Page() {
+  const products = db.product.findMany({ limit: 6 });
+
+  return (
+    <Boundary label="page.tsx" size="small" className="flex flex-col gap-5">
+      <div className="flex flex-col gap-2">
+        <h1 className="text-xl font-semibold text-gray-200">
+          Product gallery with modal interception
+        </h1>
+        <p className="max-w-2xl text-sm text-gray-400">
+          This route stays visible while the target URL updates to a nested detail
+          page. A direct load of the same URL renders the standalone detail page.
+        </p>
+      </div>
+
+      <ProductList title="Products" count={products.length}>
+        {products.map((product) => (
+          <Link key={product.id} href={`/intercepting-routes/photo/${product.id}`}>
+            <ProductCard
+              product={product}
+              className="rounded-xl border border-transparent p-2 transition hover:border-gray-800"
+            />
+          </Link>
+        ))}
+      </ProductList>
+    </Boundary>
+  );
+}

examples/app-router-playground/app/intercepting-routes/photo/[id]/page.tsx

@@ -0,0 +1,57 @@
+import db from '#/lib/db';
+import { Boundary } from '#/ui/boundary';
+import { ChevronLeftIcon } from '@heroicons/react/24/solid';
+import Image from 'next/image';
+import Link from 'next/link';
+import { notFound } from 'next/navigation';
+
+export default async function Page({
+  params,
+}: {
+  params: Promise<{ id: string }>;
+}) {
+  const { id } = await params;
+  const product = db.product.find({ where: { id } });
+  if (!product) {
+    notFound();
+  }
+
+  return (
+    <Boundary label="photo/[id]/page.tsx" className="flex flex-col gap-6">
+      <Link
+        href="/intercepting-routes"
+        className="inline-flex items-center gap-2 text-sm font-medium text-gray-400 hover:text-white"
+      >
+        <ChevronLeftIcon className="size-4" />
+        Back to gallery
+      </Link>
+
+      <div className="grid gap-6 lg:grid-cols-[minmax(0,20rem)_1fr]">
+        <div className="overflow-hidden rounded-2xl bg-gray-900/60 p-8">
+          <Image
+            src={`/shop/${product.image}`}
+            alt={product.name}
+            width={400}
+            height={400}
+            className="mx-auto brightness-150"
+          />
+        </div>
+
+        <div className="flex flex-col gap-4">
+          <div className="text-sm uppercase tracking-[0.2em] text-gray-500">
+            Direct visit
+          </div>
+          <h1 className="text-3xl font-semibold text-white">{product.name}</h1>
+          <p className="max-w-xl text-sm leading-6 text-gray-400">
+            Loading this URL directly should render the standalone page. Navigating
+            from the gallery should keep the gallery visible and render this content
+            in the parallel modal slot instead.
+          </p>
+          <div className="font-mono text-sm text-cyan-300">
+            {`$${product.price.toFixed(2)}`}
+          </div>
+        </div>
+      </div>
+    </Boundary>
+  );
+}

examples/app-router-playground/app/intercepting-routes/readme.mdx

@@ -0,0 +1,7 @@
+Intercepting Routes let you mask a target URL with the current layout during navigation.
+
+- Click a product card below to navigate to its detail URL.
+- During in-app navigation, `@modal/(.)photo/[id]` should render inside the modal slot.
+- If you load the detail URL directly, `photo/[id]/page.tsx` renders as the full page instead.
+
+- [Docs](https://nextjs.org/docs/app/api-reference/file-conventions/intercepting-routes)

packages/vinext/src/routing/app-router.ts

@@ -258,7 +258,11 @@ function discoverSlotSubRoutes(
         // that useSelectedLayoutSegments() sees the correct segment list at runtime.
         rawSegments: string[];
         // Pre-computed URL parts, params, isDynamic from convertSegmentsToRouteParts.
-        converted: { urlSegments: string[]; params: string[]; isDynamic: boolean };
+        converted: {
+          urlSegments: string[];
+          params: string[];
+          isDynamic: boolean;
+        };
         slotPages: Map<string, string>;
       }
     >();