feat: add Rspack support to Nuxt federation

.changeset/bright-rspack-builds.md

@@ -0,0 +1,5 @@
+---
+"@module-federation/nuxt": minor
+---
+
+Add client and server Module Federation support for Nuxt applications using the Rspack builder, including development and production SSR, dedicated Rspack examples, and an Rslib-based package build.

README.md

@@ -1,6 +1,6 @@
 # Nuxt Module Federation
 
-Use Module Federation in Nuxt applications with `@module-federation/nuxt`, built on top of `@module-federation/vite`.
+Use Module Federation in Nuxt applications with `@module-federation/nuxt`, using Vite or Rspack.
 
 > [!IMPORTANT]
 > `@module-federation/nuxt` is still in beta. Expect API changes while the integration settles. Please report bugs and edge cases in this repository.
@@ -10,7 +10,7 @@ Use Module Federation in Nuxt applications with `@module-federation/nuxt`, built
 - Nuxt module wiring for Module Federation hosts and remotes.
 - Convention-based component exposes from `~/components/exposed`.
 - Remote Vue components registered in Nuxt for template auto-imports.
-- Server-rendered remote components in development and production on writable Node deployments.
+- Server-rendered remote components with Vite or Rspack in development and production on writable Node deployments.
 - Client and server remote entries plus an MF manifest at the public root.
 - `vue` and `vue-router` shared as singletons by default.
 
@@ -83,12 +83,14 @@ Remote components render on the Nuxt server by default. Production remotes publi
 
 The default upstream SSR loader writes fetched modules to `node_modules/.ssr-cache` below the server working directory. Use `moduleFederation.ssr: false` for read-only or serverless deployments; see the package deployment contract for details.
 
-Nuxt 4.5 uses Vite 8's Rolldown pipeline. The MF server runner uses its ModuleRunner protocol, so remote components render during `nuxt dev` as well as production. Set `moduleFederation.ssr` to `false` to choose client-only rendering in every environment.
+With Vite, the MF server runner uses Vite 8's ModuleRunner protocol. With Rspack, the module publishes a portable server bundle graph and loads it through the same SSR runtime contract. Both builders render remote components during `nuxt dev` and production. Set `moduleFederation.ssr` to `false` to choose client-only rendering in every environment.
 
 ## Example applications
 
-- Host: [`apps/host`](apps/host) at `http://localhost:4173`
-- Remote: [`apps/remote`](apps/remote) at `http://localhost:4174`
+- Vite host: [`apps/host`](apps/host) at `http://localhost:4173`
+- Vite remote: [`apps/remote`](apps/remote) at `http://localhost:4174`
+- Rspack host: [`apps/host-rspack`](apps/host-rspack) at `http://localhost:4175`
+- Rspack remote: [`apps/remote-rspack`](apps/remote-rspack) at `http://localhost:4176`
 
 Run both from the repository root:
 
@@ -104,19 +106,55 @@ pnpm dev:remote
 pnpm dev:host
 ```
 
-The ports are fixed because the host's remote URL depends on the remote remaining at `4174`.
+The ports are fixed because each host's remote URL depends on its remote remaining at the configured port.
+
+### Rspack
+
+Nuxt's Rspack builder creates its compilers through Rsbuild, then exposes the generated low-level configuration through Nuxt's `rspack:config` hook. The module attaches `@module-federation/enhanced/rspack` there. Browser builds enable `experiments.asyncStartup`; server builds intentionally use synchronous startup for Nuxt SSR.
+
+Install the builder and select it in each application:
+
+```bash
+pnpm add -D @nuxt/rspack-builder
+```
+
+```ts
+export default defineNuxtConfig({
+  builder: "rspack",
+  modules: ["@module-federation/nuxt"],
+  moduleFederation: {
+    config: {
+      name: "host",
+      remotes: {
+        remote: "remote@https://remote.example.com/mf-manifest.json",
+      },
+    },
+  },
+});
+```
+
+Rspack remotes publish `remoteEntry.js`, `remoteEntry.ssr.js`, and the manifest at `moduleFederation.base` (`/` by default), with the portable server chunk graph under the configured `app.buildAssetsDir`. Hosts use the server entry before hydration and the browser entry afterward.
+
+Nuxt's Rspack development middleware accepts only same-origin asset requests. The dedicated Rspack host proxies the remote's manifest, entry, and chunks through `localhost:4175`; see [`apps/host-rspack/nuxt.config.ts`](apps/host-rspack/nuxt.config.ts). Deployed applications can use direct remote URLs when their production server permits cross-origin federation assets.
+
+Run the example pair with Rspack:
+
+```bash
+pnpm dev:rspack
+```
 
 ## Build checks
 
 ```bash
 pnpm typecheck
 pnpm build
+pnpm build:rspack
 pnpm test
 pnpm test:e2e
 pnpm pack:nuxt
 ```
 
-For a production smoke test, start both built applications with `pnpm preview`, then open `http://localhost:4173` and confirm the remote cards are present before hydration and remain interactive afterward.
+For a production smoke test, start both built applications with `pnpm preview` or `pnpm preview:rspack`, then open the matching host and confirm the remote cards are present before hydration and remain interactive afterward.
 
 ## Release flow
 
@@ -128,7 +166,7 @@ For a production smoke test, start both built applications with `pnpm preview`,
 ## Repository layout
 
 - Package: `packages/nuxt`
-- Host example: `apps/host`
-- Remote example: `apps/remote`
+- Vite examples: `apps/host`, `apps/remote`
+- Rspack examples: `apps/host-rspack`, `apps/remote-rspack`
 - Package reference: `packages/nuxt/README.md`
 - Release guide: `docs/RELEASING.md`

apps/host-rspack/README.md

@@ -0,0 +1,11 @@
+# Rspack host
+
+Nuxt Rspack host at `http://localhost:4175`. It server-renders the remote components, then hydrates them with the browser entry.
+
+The host proxies the remote federation routes through its own origin because Nuxt's Rspack development middleware only serves same-origin requests.
+
+Run the Rspack pair from the repository root:
+
+```bash
+pnpm dev:rspack
+```

apps/host-rspack/nuxt.config.ts

@@ -0,0 +1,25 @@
+const hostOrigin = "http://localhost:4175";
+const remoteOrigin = "http://localhost:4176";
+const remoteBase = "/rspack-remote-mf";
+const remoteAssets = "/rspack-remote-assets";
+
+export default defineNuxtConfig({
+  extends: ["../host"],
+  builder: "rspack",
+  routeRules: {
+    [`${remoteBase}/**`]: {
+      proxy: `${remoteOrigin}${remoteBase}/**`,
+    },
+    [`${remoteAssets}/**`]: {
+      proxy: `${remoteOrigin}${remoteAssets}/**`,
+    },
+  },
+  moduleFederation: {
+    config: {
+      name: "hostRspack",
+      remotes: {
+        remote: `remote@${hostOrigin}${remoteBase}/mf-manifest.json`,
+      },
+    },
+  },
+});

apps/host-rspack/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "nuxt-host-rspack",
+  "type": "module",
+  "scripts": {
+    "build": "nuxt build",
+    "predev": "nuxt prepare",
+    "dev": "nuxt dev --port 4175",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview --port 4175",
+    "typecheck": "nuxt typecheck"
+  },
+  "dependencies": {
+    "@module-federation/nuxt": "workspace:*",
+    "nuxt": "4.5.1",
+    "vue": "3.5.40",
+    "vue-router": "5.2.0"
+  },
+  "devDependencies": {
+    "@nuxt/rspack-builder": "4.5.1"
+  }
+}

apps/host-rspack/tsconfig.json

@@ -0,0 +1,3 @@
+{
+  "extends": "./.nuxt/tsconfig.json"
+}

apps/remote-rspack/README.md

@@ -0,0 +1,11 @@
+# Rspack remote
+
+Nuxt Rspack remote at `http://localhost:4176`.
+
+Federation assets use `/rspack-remote-mf`; compiled browser chunks and the portable SSR graph use `/rspack-remote-assets`. The Rspack host proxies both paths for same-origin development loading.
+
+Run the Rspack pair from the repository root:
+
+```bash
+pnpm dev:rspack
+```

apps/remote-rspack/nuxt.config.ts

@@ -0,0 +1,20 @@
+import { fileURLToPath } from "node:url";
+
+const exposedDir = fileURLToPath(
+  new URL("../remote/app/components/exposed", import.meta.url),
+);
+
+export default defineNuxtConfig({
+  extends: ["../remote"],
+  builder: "rspack",
+  app: {
+    buildAssetsDir: "/rspack-remote-assets/",
+  },
+  moduleFederation: {
+    base: "/rspack-remote-mf",
+    exposedDir,
+    config: {
+      name: "remote",
+    },
+  },
+});

apps/remote-rspack/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "nuxt-remote-rspack",
+  "type": "module",
+  "scripts": {
+    "build": "nuxt build",
+    "predev": "nuxt prepare",
+    "dev": "nuxt dev --port 4176",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview --port 4176",
+    "typecheck": "nuxt typecheck"
+  },
+  "dependencies": {
+    "@module-federation/nuxt": "workspace:*",
+    "nuxt": "4.5.1",
+    "vue": "3.5.40",
+    "vue-router": "5.2.0"
+  },
+  "devDependencies": {
+    "@nuxt/rspack-builder": "4.5.1"
+  }
+}

apps/remote-rspack/tsconfig.json

@@ -0,0 +1,3 @@
+{
+  "extends": "./.nuxt/tsconfig.json"
+}

apps/remote/nuxt.config.ts

@@ -15,6 +15,7 @@ export default defineNuxtConfig({
       filename: "remoteEntry.js",
       remotes: {},
       manifest: true,
+      moduleParseIdleTimeout: 30,
     },
   },
   vite: {

package.json

@@ -3,9 +3,14 @@
   "private": true,
   "scripts": {
     "build": "turbo run build",
+    "build:rspack": "turbo run build --filter=nuxt-host-rspack --filter=nuxt-remote-rspack",
     "build:package": "pnpm --filter @module-federation/nuxt build",
-    "preview": "pnpm --filter @module-federation/nuxt build && turbo run preview",
-    "dev": "pnpm --filter @module-federation/nuxt build && turbo run dev",
+    "preview": "pnpm --filter @module-federation/nuxt build && turbo run preview --filter=nuxt-host --filter=nuxt-remote",
+    "preview:rspack": "pnpm --filter @module-federation/nuxt build && turbo run preview --filter=nuxt-host-rspack --filter=nuxt-remote-rspack",
+    "dev": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-host --filter=nuxt-remote",
+    "dev:rspack": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-host-rspack --filter=nuxt-remote-rspack",
+    "dev:rspack:host": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-host-rspack",
+    "dev:rspack:remote": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-remote-rspack",
     "dev:host": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-host",
     "dev:remote": "pnpm --filter @module-federation/nuxt build && turbo run dev --filter=nuxt-remote",
     "test": "node --test --test-concurrency=1 test/*.test.mjs",

packages/nuxt/README.md

@@ -1,12 +1,14 @@
 # @module-federation/nuxt
 
-Nuxt integration for Module Federation, built on top of `@module-federation/vite`.
+Nuxt integration for Module Federation, using `@module-federation/vite` or `@module-federation/enhanced/rspack`.
 
 ## Requirements
 
 - Nuxt `>=4.5.1` (Vite 8 with Rolldown)
 - Node.js `^22.18.0`, `^24.11.0`, or `>=26.0.0`
 
+Rspack applications also require `@nuxt/rspack-builder` matching the installed Nuxt version.
+
 Production builds support server-rendered remote components on writable Node deployments. The default upstream SSR loader writes fetched modules under `process.cwd()/node_modules/.ssr-cache`; read-only and serverless filesystems are not currently supported for remote SSR.
 
 ## Install
@@ -118,7 +120,32 @@ Only expose names beginning with a letter and containing letters, numbers, under
 - The Nuxt server loads `remoteEntry.ssr.js`.
 - The remote component's HTML is included in the host response and hydrated in the browser.
 
-Nuxt 4.5 uses Vite 8's Rolldown pipeline. The same federation plugin participates in the client and server environments, so remote components render during both `nuxt dev` and production SSR.
+Vite uses its ModuleRunner protocol for the server graph. Rspack emits a separate portable server graph. Both builders render remote components during `nuxt dev` and production SSR.
+
+### Rspack builder
+
+Set `builder: "rspack"` and install `@nuxt/rspack-builder` to use federation through `@module-federation/enhanced/rspack`:
+
+```ts
+export default defineNuxtConfig({
+  builder: "rspack",
+  modules: ["@module-federation/nuxt"],
+  moduleFederation: {
+    config: {
+      name: "shell",
+      remotes: {
+        catalog: "catalog@https://catalog.example.com/mf-manifest.json",
+      },
+    },
+  },
+});
+```
+
+Nuxt creates Rspack compilers through Rsbuild internally, but its module API exposes the generated configuration through `rspack:config`; the Nuxt module installs the Rspack federation plugin at that hook. Browser builds enable `experiments.asyncStartup`; the server build uses synchronous startup so Nuxt can evaluate its SSR entry normally.
+
+Rspack remotes publish `remoteEntry.js`, `remoteEntry.ssr.js`, and `mf-manifest.json` at `moduleFederation.base` (`/` by default), with the server entry's portable chunk graph under `app.buildAssetsDir`. The manifest includes `ssrRemoteEntry` and a `nuxtSsrBuildHash`, allowing hosts to load the server graph before hydration and detect later deployments.
+
+Nuxt's Rspack development middleware rejects cross-origin asset requests even when CORS headers are present. For cross-port local development, proxy the remote manifest and its configured `app.buildAssetsDir` through the host origin. The repository's `host-rspack` and `remote-rspack` examples provide a complete proxy setup. Production servers that allow cross-origin assets can use direct remote URLs.
 
 Development remote manifests infer their asset origin from the manifest URL. This keeps `remoteEntry.js` and exposed chunks on the remote origin when the host and remote use different ports. An explicit `config.publicPath` still takes precedence.
 
@@ -203,9 +230,9 @@ Configure these values under `moduleFederation` in `nuxt.config.ts`.
 | `ssr`                    | `boolean`                          | `true`                   | Render consumed remote components on the Nuxt server. Server exposes are still published when `false`. |
 | `ssrFetchTimeoutMs`      | `number`                           | `10000`                  | Maximum time for each SSR remote network request; `0` disables the timeout.                            |
 | `ssrManifestMaxAgeMs`    | `number`                           | `30000`                  | Interval before the server re-checks a remote manifest for a new release.                              |
-| `config`                 | `Partial<ModuleFederationOptions>` | See below                | Options passed to `@module-federation/vite`.                                                           |
+| `config`                 | `Partial<ModuleFederationOptions>` | See below                | Options passed to the selected Vite or Rspack federation plugin.                                       |
 
-The MF Vite config defaults are:
+The common federation config defaults are:
 
 ```ts
 {

packages/nuxt/package.json

@@ -2,12 +2,12 @@
   "name": "@module-federation/nuxt",
   "version": "0.1.0",
   "type": "module",
-  "description": "Nuxt module for Module Federation using @module-federation/vite",
+  "description": "Nuxt module for Module Federation using Vite or Rspack",
   "license": "MIT",
   "sideEffects": false,
   "main": "./dist/federation.mjs",
   "module": "./dist/federation.mjs",
-  "types": "./dist/federation.d.mts",
+  "types": "./dist/federation.d.ts",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/module-federation/nuxt.git",
@@ -24,17 +24,17 @@
   ],
   "exports": {
     ".": {
-      "types": "./dist/federation.d.mts",
+      "types": "./dist/federation.d.ts",
       "import": "./dist/federation.mjs",
       "default": "./dist/federation.mjs"
     },
     "./shared-strategy": {
-      "types": "./dist/shared-strategy.d.mts",
+      "types": "./dist/shared-strategy.d.ts",
       "import": "./dist/shared-strategy.mjs",
       "default": "./dist/shared-strategy.mjs"
     },
     "./ssr-entry-loader": {
-      "types": "./dist/ssr-entry-loader.d.mts",
+      "types": "./dist/ssr-entry-loader.d.ts",
       "import": "./dist/ssr-entry-loader.mjs",
       "default": "./dist/ssr-entry-loader.mjs"
     },
@@ -50,8 +50,8 @@
     "provenance": true
   },
   "scripts": {
-    "build": "tsdown",
-    "dev": "tsdown --watch --no-clean",
+    "build": "rslib build",
+    "dev": "rslib build --watch --no-clean",
     "pack:dry": "npm pack --dry-run",
     "prepack": "pnpm run build",
     "prepublishOnly": "pnpm run typecheck && pnpm run build",
@@ -61,18 +61,20 @@
     "node": "^22.18.0 || ^24.11.0 || >=26.0.0"
   },
   "dependencies": {
+    "@module-federation/enhanced": "2.8.1",
     "@module-federation/runtime": "2.8.1",
     "@module-federation/vite": "1.20.0",
     "@nuxt/kit": "^4.5.1",
-    "@nuxt/schema": "^4.5.1"
+    "@nuxt/schema": "^4.5.1",
+    "acorn": "8.15.0"
   },
   "peerDependencies": {
     "nuxt": ">=4.5.1"
   },
   "devDependencies": {
+    "@rslib/core": "0.23.2",
     "@types/node": "^26.1.2",
     "nuxt": "4.5.1",
-    "tsdown": "^0.22.14",
     "vue-tsc": "3.3.8"
   }
 }