feat(nuxt): support multiple nuxtApps at runtime (#27068)

docs/3.api/2.composables/use-nuxt-app.md

@@ -18,6 +18,14 @@ const nuxtApp = useNuxtApp()
 
 If runtime context is unavailable in your scope, `useNuxtApp` will throw an exception when called. You can use [`tryUseNuxtApp`](#tryusenuxtapp) instead for composables that do not require `nuxtApp`, or to simply check if context is available or not without an exception.
 
+<!--
+note
+By default, the shared runtime context of Nuxt is namespaced under the [`buildId`](/docs/api/nuxt-config#buildid) option. It allows the support of multiple runtime contexts.
+
+## Params
+
+- `appName`: an optional application name. If you do not provide it, the Nuxt `buildId` option is used. Otherwise, it must match with an existing `buildId`. -->
+
 ## Methods
 
 ### `provide (name, value)`
@@ -278,3 +286,7 @@ export function useStandType() {
   }
 }
 ```
+
+<!-- ### Params
+
+- `appName`: an optional application name. If you do not provide it, the Nuxt `buildId` option is used. Otherwise, it must match with an existing `buildId`. -->

packages/nuxt/src/app/nuxt.ts

@@ -22,9 +22,14 @@ import type { ViewTransition } from './plugins/view-transitions.client'
 
 import type { NuxtAppLiterals } from '#app'
 
-const nuxtAppCtx = /* @__PURE__ */ getContext<NuxtApp>('nuxt-app', {
-  asyncContext: !!__NUXT_ASYNC_CONTEXT__ && import.meta.server,
-})
+// @ts-expect-error virtual import
+import { buildId } from '#build/nuxt.config.mjs'
+
+function getNuxtAppCtx (appName?: string) {
+  return getContext<NuxtApp>(appName || buildId || 'nuxt-app', {
+    asyncContext: !!__NUXT_ASYNC_CONTEXT__ && import.meta.server,
+  })
+}
 
 type HookResult = Promise<void> | void
 
@@ -93,6 +98,8 @@ export interface NuxtPayload {
 }
 
 interface _NuxtApp {
+  /** @internal */
+  _name: string
   vueApp: App<Element>
   globalName: string
   versions: Record<string, string>
@@ -237,6 +244,7 @@ export interface CreateOptions {
 export function createNuxtApp (options: CreateOptions) {
   let hydratingCount = 0
   const nuxtApp: NuxtApp = {
+    name: buildId,
     _scope: effectScope(),
     provide: undefined,
     globalName: 'nuxt',
@@ -447,6 +455,7 @@ export function isNuxtPlugin (plugin: unknown) {
  */
 export function callWithNuxt<T extends (...args: any[]) => any> (nuxt: NuxtApp | _NuxtApp, setup: T, args?: Parameters<T>) {
   const fn: () => ReturnType<T> = () => args ? setup(...args as Parameters<T>) : setup()
+  const nuxtAppCtx = getNuxtAppCtx(nuxt._name)
   if (import.meta.server) {
     return nuxt.vueApp.runWithContext(() => nuxtAppCtx.callAsync(nuxt as NuxtApp, fn))
   } else {
@@ -463,13 +472,14 @@ export function callWithNuxt<T extends (...args: any[]) => any> (nuxt: NuxtApp |
  * Returns `null` if Nuxt instance is unavailable.
  * @since 3.10.0
  */
-export function tryUseNuxtApp (): NuxtApp | null {
+export function tryUseNuxtApp (): NuxtApp | null
+export function tryUseNuxtApp (appName?: string): NuxtApp | null {
   let nuxtAppInstance
   if (hasInjectionContext()) {
     nuxtAppInstance = getCurrentInstance()?.appContext.app.$nuxt
   }
 
-  nuxtAppInstance = nuxtAppInstance || nuxtAppCtx.tryUse()
+  nuxtAppInstance = nuxtAppInstance || getNuxtAppCtx(appName).tryUse()
 
   return nuxtAppInstance || null
 }
@@ -481,8 +491,10 @@ export function tryUseNuxtApp (): NuxtApp | null {
  * Throws an error if Nuxt instance is unavailable.
  * @since 3.0.0
  */
-export function useNuxtApp (): NuxtApp {
-  const nuxtAppInstance = tryUseNuxtApp()
+export function useNuxtApp (): NuxtApp
+export function useNuxtApp (appName?: string): NuxtApp {
+  // @ts-expect-error internal usage of appName
+  const nuxtAppInstance = tryUseNuxtApp(appName)
 
   if (!nuxtAppInstance) {
     if (import.meta.dev) {

packages/nuxt/src/core/nitro.ts

@@ -3,7 +3,6 @@ import { existsSync, promises as fsp, readFileSync } from 'node:fs'
 import { cpus } from 'node:os'
 import { join, relative, resolve } from 'pathe'
 import { createRouter as createRadixRouter, exportMatcher, toRouteMatcher } from 'radix3'
-import { randomUUID } from 'uncrypto'
 import { joinURL, withTrailingSlash } from 'ufo'
 import { build, copyPublicAssets, createDevServer, createNitro, prepare, prerender, scanHandlers, writeTypes } from 'nitropack'
 import type { Nitro, NitroConfig, NitroOptions } from 'nitropack'
@@ -237,7 +236,7 @@ export async function initNitro (nuxt: Nuxt & { _nitro?: Nitro }) {
   if (nuxt.options.experimental.appManifest) {
     // @ts-expect-error untyped nuxt property
     const buildId = nuxt.options.appConfig.nuxt!.buildId ||=
-      (nuxt.options.dev ? 'dev' : nuxt.options.test ? 'test' : randomUUID())
+      (nuxt.options.dev ? 'dev' : nuxt.options.test ? 'test' : nuxt.options.buildId)
     const buildTimestamp = Date.now()
 
     const manifestPrefix = joinURL(nuxt.options.app.buildAssetsDir, 'builds')

packages/nuxt/src/core/templates.ts

@@ -397,6 +397,7 @@ export const nuxtConfigTemplate: NuxtTemplate = {
       `export const fetchDefaults = ${JSON.stringify(fetchDefaults)}`,
       `export const vueAppRootContainer = ${ctx.nuxt.options.app.rootId ? `'#${ctx.nuxt.options.app.rootId}'` : `'body > ${ctx.nuxt.options.app.rootTag}'`}`,
       `export const viewTransition = ${ctx.nuxt.options.experimental.viewTransition}`,
+      `export const buildId = ${JSON.stringify(ctx.nuxt.options.buildId)}`,
     ].join('\n\n')
   },
 }

packages/schema/package.json

@@ -72,6 +72,7 @@
     "std-env": "^3.7.0",
     "ufo": "^1.5.3",
     "unimport": "^3.7.1",
+    "uncrypto": "^0.1.3",
     "untyped": "^1.4.2"
   },
   "engines": {

packages/schema/src/config/common.ts

@@ -4,6 +4,7 @@ import { join, relative, resolve } from 'pathe'
 import { isDebug, isDevelopment, isTest } from 'std-env'
 import { defu } from 'defu'
 import { findWorkspaceDir } from 'pkg-types'
+import { randomUUID } from 'uncrypto'
 import type { RuntimeConfig } from '../types/config'
 
 export default defineUntypedSchema({
@@ -153,6 +154,13 @@ export default defineUntypedSchema({
     $resolve: async (val: string | undefined, get): Promise<string> => resolve(await get('rootDir') as string, val || '.nuxt'),
   },
 
+  /**
+   * A unique identifier matching the build. This may contain the hash of the current state of the project.
+   */
+  buildId: {
+    $resolve: (val: string) => val ?? randomUUID(),
+  },
+
   /**
    * Used to set the modules directories for path resolving (for example, webpack's
    * `resolveLoading`, `nodeExternals` and `postcss`).

pnpm-lock.yaml

@@ -463,6 +463,9 @@ importers:
       ufo:
         specifier: ^1.5.3
         version: 1.5.3
+      uncrypto:
+        specifier: ^0.1.3
+        version: 0.1.3
       unimport:
         specifier: ^3.7.1
         version: 3.7.1(rollup@4.17.2)

test/basic.test.ts

@@ -2642,3 +2642,42 @@ describe('defineNuxtComponent watch duplicate', () => {
     expect(await page.getByTestId('define-nuxt-component-state').first().innerText()).toBe('2')
   })
 })
+
+describe('namespace access to useNuxtApp', () => {
+  it('should return the nuxt instance when used with correct buildId', async () => {
+    const { page, pageErrors } = await renderPage('/namespace-nuxt-app')
+
+    expect(pageErrors).toEqual([])
+
+    await page.waitForFunction(() => window.useNuxtApp?.() && !window.useNuxtApp?.().isHydrating)
+
+    // Defaulting to buildId
+    await page.evaluate(() => window.useNuxtApp?.())
+    // Using correct configured buildId
+    // @ts-expect-error not public API yet
+    await page.evaluate(() => window.useNuxtApp?.('nuxt-app-basic'))
+
+    await page.close()
+  })
+
+  it('should throw an error when used with wrong buildId', async () => {
+    const { page, pageErrors } = await renderPage('/namespace-nuxt-app')
+
+    expect(pageErrors).toEqual([])
+
+    await page.waitForFunction(() => window.useNuxtApp?.() && !window.useNuxtApp?.().isHydrating)
+
+    let error: unknown
+    try {
+      // Using wrong/unknown buildId
+      // @ts-expect-error not public API yet
+      await page.evaluate(() => window.useNuxtApp?.('nuxt-app-unknown'))
+    } catch (err) {
+      error = err
+    }
+
+    expect(error).toBeTruthy()
+
+    await page.close()
+  })
+})

test/fixtures/basic/nuxt.config.ts

@@ -32,6 +32,7 @@ export default defineNuxtConfig({
   },
   buildDir: process.env.NITRO_BUILD_DIR,
   builder: process.env.TEST_BUILDER as 'webpack' | 'vite' ?? 'vite',
+  buildId: 'nuxt-app-basic',
   build: {
     transpile: [
       (ctx) => {

test/fixtures/basic/pages/namespace-nuxt-app.vue

@@ -0,0 +1,10 @@
+<script setup lang="ts">
+// Defaulting to buildId
+useNuxtApp()
+// Using correct configured buildId
+useNuxtApp('nuxt-app-basic')
+</script>
+
+<template>
+  <div>Nuxt instance available</div>
+</template>

vitest.nuxt.config.ts

@@ -13,6 +13,7 @@ export default defineVitestConfig({
     environmentOptions: {
       nuxt: {
         overrides: {
+          buildId: 'nuxt-app',
           experimental: {
             appManifest: process.env.TEST_MANIFEST !== 'manifest-off',
           },