fix(nuxt): delay navigation until user input is acknowledged (#27743)

packages/nuxt/src/app/plugins/navigation-repaint.client.ts

@@ -0,0 +1,19 @@
+import { defineNuxtPlugin } from '../nuxt'
+import { useRouter } from '../composables'
+
+export default defineNuxtPlugin(() => {
+  useRouter().beforeResolve(async () => {
+    /**
+     * This gives an opportunity for the browser to repaint, acknowledging user interaction.
+     * It can reduce INP when navigating on prerendered routes.
+     *
+     * @see https://github.com/nuxt/nuxt/issues/26271#issuecomment-2178582037
+     * @see https://vercel.com/blog/demystifying-inp-new-tools-and-actionable-insights
+     */
+    await new Promise((resolve) => {
+      // Ensure we always resolve, even if the animation frame never fires
+      setTimeout(resolve, 100)
+      requestAnimationFrame(() => { setTimeout(resolve, 0) })
+    })
+  })
+})

packages/nuxt/src/core/nuxt.ts

@@ -533,6 +533,12 @@ async function initNuxt (nuxt: Nuxt) {
     }
   }
 
+  if (nuxt.options.experimental.navigationRepaint) {
+    addPlugin({
+      src: resolve(nuxt.options.appDir, 'plugins/navigation-repaint.client'),
+    })
+  }
+
   nuxt.hooks.hook('builder:watch', (event, relativePath) => {
     const path = resolve(nuxt.options.srcDir, relativePath)
     // Local module patterns

packages/nuxt/test/app.test.ts

@@ -43,6 +43,10 @@ describe('resolveApp', () => {
             "mode": "client",
             "src": "<repoRoot>/packages/nuxt/src/app/plugins/payload.client.ts",
           },
+          {
+            "mode": "client",
+            "src": "<repoRoot>/packages/nuxt/src/app/plugins/navigation-repaint.client.ts",
+          },
           {
             "mode": "client",
             "src": "<repoRoot>/packages/nuxt/src/app/plugins/check-outdated-build.client.ts",

packages/schema/src/config/experimental.ts

@@ -513,5 +513,13 @@ export default defineUntypedSchema({
         return val ?? ((await get('future') as Record<string, unknown>).compatibilityVersion !== 4)
       },
     },
+
+    /**
+     * Wait for a single animation frame before navigation, which gives an opportunity
+     * for the browser to repaint, acknowledging user interaction.
+     *
+     * It can reduce INP when navigating on prerendered routes.
+     */
+    navigationRepaint: true,
   },
 })