fix: stabilize TanStack SSR remote revalidation (#5)

Author: dmchoi77

.changeset/tidy-ssr-revalidation.md

@@ -0,0 +1,5 @@
+---
+"@module-federation/tanstack": patch
+---
+
+add server-entry revalidation for TanStack Start SSR federation hosts

TODO.md

@@ -145,7 +145,15 @@ Fixed upstream in `@module-federation/vite` 1.23.3:
       the host, and prove no stale container or shared module is served.
       `@module-federation/vite` has `revalidate()` and `maxAgeMs` for its own
       loader; the Module Federation runtime caches containers for the life of
-      the process.
+      the process. Server-entry revalidation is now available for Vite hosts
+      through `ssrEntryLoader.maxAgeMs` and for Rsbuild hosts through
+      `server.ssrEntryLoader.maxAgeMs`. For Vite's native loader, a manifest
+      provides the version needed for automatic change detection; direct or
+      convention-resolved server-entry URLs need an explicit `revalidate()` for
+      forced refresh. Shared-singleton changes still require a host restart, so
+      the shared-module portion remains open. Remote module-scope side effects
+      are not automatically disposed during revalidation and remain the
+      application's responsibility.
 - [ ] Test cyclic imports across chunks in a server remote graph.
 - [ ] In development, a Vite remote's server modules import React from the files
       its dev server resolves, so host and remote must resolve React to the

packages/tanstack/README.md

@@ -63,6 +63,22 @@ A Vite host renders before lazy shared modules resolve, so mark any other shared
 package the host imports from its entry or root route as `eager: true`, as the
 wrapper does for React. Remotes can keep their shares lazy.
 
+For a Vite host, configure SSR entry revalidation directly with the Vite
+option:
+
+```ts
+tanstackStartModuleFederation({
+  name: "host",
+  ssrEntryLoader: { maxAgeMs: 30_000 },
+  // ...remotes and shared options
+});
+```
+
+Vite's `maxAgeMs` revalidation is version-aware when the remote is resolved
+from an `mf-manifest.json`. Convention-resolved or direct server-entry URLs do
+not provide a remote version; use a manifest URL or call the Vite loader's
+explicit `revalidate()` when those URLs must be refreshed.
+
 The wrapper omits the global Module Federation `target` option. TanStack
 Start's client and SSR environments need `@module-federation/vite` to select
 `web` and `node` independently.
@@ -151,6 +167,43 @@ When a remote's server entry cannot load, the host's runtime plugin throws a
 `RemoteEntryError` whose `phase` is `fetch`, `evaluate`, or `loader` and whose
 `cause` is the original error.
 
+Server entries are cached for the lifetime of the Node process by default. To
+pick up a rebuilt remote while keeping the process running, configure the
+revalidation window on an Rsbuild host:
+
+```ts
+tanstackStartModuleFederation({
+  federation: {
+    name: "host",
+    remotes: {
+      remote: "remote@https://example.test/mf-manifest.json",
+    },
+  },
+  server: {
+    ssrEntryLoader: {
+      maxAgeMs: 30_000,
+    },
+  },
+});
+```
+
+For an Rsbuild host, when `maxAgeMs` expires, the adapter invalidates the
+Module Federation remote container cache. Vite remotes also invalidate the Vite
+SSR entry-loader cache; the option is forwarded to that loader. `strategy` and
+`fetchMaxBytes` apply to Vite SSR entries, while `fetchTimeoutMs` applies to
+both Vite and CommonJS server-entry requests. Set either limit to `0` to
+disable it. Concurrent requests for an expired remote share one revalidation
+request on this adapter path.
+
+Revalidation makes subsequent loads use the new remote entry and exposed
+modules, but does not safely replace already loaded process-level shared
+singletons such as React. Restart the host process after changing a shared
+singleton's version or implementation. For Rsbuild/CommonJS remotes,
+expiration also re-evaluates the downloaded server entry with a forced
+container re-registration. Module-scope side effects in a remote (for example
+timers or process listeners) are not automatically disposed, so use
+revalidation only for remotes whose evaluation is safe to repeat.
+
 ## Rendering remotes on the server
 
 Hosts on either bundler render remotes the same way: load the remote in the

packages/tanstack/src/node-entry-loader.ts

@@ -1,11 +1,22 @@
-import type { ModuleFederationRuntimePlugin } from "@module-federation/runtime";
+import type { ModuleFederation, ModuleFederationRuntimePlugin } from "@module-federation/runtime";
 
 type LoadEntryArgs = Parameters<NonNullable<ModuleFederationRuntimePlugin["loadEntry"]>>[0];
 type RemoteEntryExports = NonNullable<LoadEntryArgs["remoteEntryExports"]>;
 type RemoteInfo = LoadEntryArgs["remoteInfo"];
 type FederationHost = LoadEntryArgs["origin"];
 type NodeModule = typeof import("node:module");
 
+export interface NodeEntryLoaderOptions {
+  /** Re-check manifest/server entries after this many milliseconds. Omit to cache until exit. */
+  maxAgeMs?: number;
+  /** Revalidation strategy used by the Vite SSR entry loader. */
+  strategy?: "temp-file" | "vm";
+  /** Maximum time for a server-entry request. Defaults to 10 seconds; 0 disables the timeout. */
+  fetchTimeoutMs?: number;
+  /** Maximum server-entry response size for Vite remotes; 0 disables the limit. */
+  fetchMaxBytes?: number;
+}
+
 /** A remote's server entry failed to load. `phase` says which step failed; `cause` keeps the original error. */
 export class RemoteEntryError extends Error {
   readonly phase: "fetch" | "evaluate" | "loader";
@@ -34,14 +45,25 @@ export class RemoteEntryError extends Error {
  *   handles both production builds and Vite dev servers. It is loaded with Node's
  *   `require`, not the bundle's, so its `import()` calls work in Rsbuild's runner too.
  */
-export default function nodeEntryLoaderPlugin(): ModuleFederationRuntimePlugin {
+export default function nodeEntryLoaderPlugin(
+  options: NodeEntryLoaderOptions = {},
+): ModuleFederationRuntimePlugin {
+  const revalidationHooks = isRevalidationEnabled(options.maxAgeMs)
+    ? createRevalidationHooks(options.maxAgeMs)
+    : {};
+
   return {
     name: "tanstack-start-node-entry-loader",
+    ...revalidationHooks,
     async loadEntry(args) {
       const { remoteInfo } = args;
       if (!isNodeServer() || !/^https?:\/\//.test(remoteInfo.entry)) return undefined;
-      if (remoteInfo.type === "commonjs-module") return loadCommonJsEntry(remoteInfo);
-      if (remoteInfo.type === "module" || remoteInfo.type === "esm") return loadModuleEntry(args);
+      if (remoteInfo.type === "commonjs-module") {
+        return loadCommonJsEntry(remoteInfo, options.fetchTimeoutMs);
+      }
+      if (remoteInfo.type === "module" || remoteInfo.type === "esm") {
+        return loadModuleEntry(args, options);
+      }
       return undefined;
     },
   };
@@ -50,6 +72,11 @@ export default function nodeEntryLoaderPlugin(): ModuleFederationRuntimePlugin {
 // Matches @module-federation/vite's SSR fetch timeout.
 const FETCH_TIMEOUT_MS = 10_000;
 
+function requestOptions(fetchTimeoutMs: number | undefined) {
+  const timeout = fetchTimeoutMs ?? FETCH_TIMEOUT_MS;
+  return timeout === 0 ? {} : { signal: AbortSignal.timeout(timeout) };
+}
+
 function isNodeServer() {
   return typeof process !== "undefined" && typeof process.getBuiltinModule === "function";
 }
@@ -68,10 +95,13 @@ function appRequires() {
     .map((base) => createRequire(base));
 }
 
-async function loadCommonJsEntry({ entry, entryGlobalName, name }: RemoteInfo) {
+async function loadCommonJsEntry(
+  { entry, entryGlobalName, name }: RemoteInfo,
+  fetchTimeoutMs = FETCH_TIMEOUT_MS,
+) {
   let source: string;
   try {
-    const response = await fetch(entry, { signal: AbortSignal.timeout(FETCH_TIMEOUT_MS) });
+    const response = await fetch(entry, requestOptions(fetchTimeoutMs));
     if (!response.ok) throw new Error(`HTTP ${response.status} ${response.statusText}`.trim());
     source = await response.text();
   } catch (cause) {
@@ -141,22 +171,34 @@ const VITE_SHARED_PACKAGES = [
 ];
 
 type ViteSsrEntryLoaderModule = {
-  default: (options: { resolvedShared: Record<string, string> }) => ModuleFederationRuntimePlugin;
+  default: (options: {
+    resolvedShared: Record<string, string>;
+    maxAgeMs?: number;
+    strategy?: "temp-file" | "vm";
+    fetchTimeoutMs?: number;
+    fetchMaxBytes?: number;
+  }) => ModuleFederationRuntimePlugin;
+  revalidate?: (remoteEntryUrl?: string) => void;
   SsrEntryHttpError?: new (...args: never[]) => Error;
 };
 
 type ViteLoader = {
   httpError?: ViteSsrEntryLoaderModule["SsrEntryHttpError"];
   plugin: ModuleFederationRuntimePlugin;
+  revalidate?: ViteSsrEntryLoaderModule["revalidate"];
   require: NodeJS.Require;
   resolvedShared: Record<string, string>;
 };
 
-let viteLoader: ViteLoader | undefined;
+const viteLoaders = new WeakMap<ModuleFederation, ViteLoader>();
 
-async function loadModuleEntry(args: LoadEntryArgs) {
+async function loadModuleEntry(args: LoadEntryArgs, options: NodeEntryLoaderOptions) {
   const { entry, name } = args.remoteInfo;
-  viteLoader ??= createViteLoader(args);
+  let viteLoader = viteLoaders.get(args.origin);
+  if (!viteLoader) {
+    viteLoader = createViteLoader(args, options);
+    viteLoaders.set(args.origin, viteLoader);
+  }
   // Shared modules the host loaded since the last remote are aligned too.
   provideHostModules(args.origin, viteLoader.resolvedShared, viteLoader.require);
 
@@ -181,7 +223,7 @@ async function loadModuleEntry(args: LoadEntryArgs) {
   if (!remoteEntry) {
     const reachable = await fetch(entry, {
       method: "HEAD",
-      signal: AbortSignal.timeout(FETCH_TIMEOUT_MS),
+      ...requestOptions(options.fetchTimeoutMs),
     }).then(
       (response) => response.ok,
       () => false,
@@ -197,7 +239,10 @@ async function loadModuleEntry(args: LoadEntryArgs) {
   return remoteEntry;
 }
 
-function createViteLoader({ origin, remoteInfo }: LoadEntryArgs): ViteLoader {
+function createViteLoader(
+  { origin, remoteInfo }: LoadEntryArgs,
+  options: NodeEntryLoaderOptions,
+): ViteLoader {
   const requires = appRequires();
   const resolve = (specifier: string) => {
     for (const require of requires) {
@@ -229,12 +274,123 @@ function createViteLoader({ origin, remoteInfo }: LoadEntryArgs): ViteLoader {
   const loaderModule = loader.require(loader.path) as ViteSsrEntryLoaderModule;
   return {
     httpError: loaderModule.SsrEntryHttpError,
-    plugin: loaderModule.default({ resolvedShared }),
+    plugin: loaderModule.default({ resolvedShared, ...options }),
+    revalidate: loaderModule.revalidate,
     require: loader.require,
     resolvedShared,
   };
 }
 
+function isRevalidationEnabled(maxAgeMs: number | undefined): maxAgeMs is number {
+  return typeof maxAgeMs === "number" && Number.isFinite(maxAgeMs) && maxAgeMs >= 0;
+}
+
+function createRevalidationHooks(maxAgeMs: number) {
+  const lastLoadedAtByOrigin = new WeakMap<ModuleFederation, Map<string, number>>();
+  // Re-registration is synchronous, but loading and evaluating the new entry is not. Keep a
+  // per-remote barrier so concurrent expired requests share that asynchronous revalidation.
+  const pendingRevalidationsByOrigin = new WeakMap<
+    ModuleFederation,
+    Map<string, PendingRevalidation>
+  >();
+
+  return {
+    async beforeRequest(context) {
+      const { id, origin } = context;
+      const remote = findRemote(origin, id);
+      if (!remote) return context;
+
+      const pendingRevalidations = getPendingRevalidations(origin);
+      const pendingRevalidation = pendingRevalidations.get(remote.name);
+      if (pendingRevalidation) {
+        await pendingRevalidation.promise;
+        return context;
+      }
+
+      const lastLoadedAt = getLastLoadedAt(origin);
+      const loadedAt = lastLoadedAt.get(remote.name);
+      if (loadedAt !== undefined && Date.now() - loadedAt >= maxAgeMs) {
+        lastLoadedAt.delete(remote.name);
+        const nextRevalidation = createPendingRevalidation();
+        pendingRevalidations.set(remote.name, nextRevalidation);
+        try {
+          invalidateRemote(origin, remote);
+        } catch (error) {
+          pendingRevalidations.delete(remote.name);
+          nextRevalidation.resolve();
+          throw error;
+        }
+      }
+      return context;
+    },
+    afterLoadRemote({ origin, remote, error }) {
+      if (!remote) return;
+      const pendingRevalidations = getPendingRevalidations(origin);
+      const lastLoadedAt = getLastLoadedAt(origin);
+      if (!error && !lastLoadedAt.has(remote.name)) lastLoadedAt.set(remote.name, Date.now());
+      const pendingRevalidation = pendingRevalidations.get(remote.name);
+      if (pendingRevalidation) {
+        pendingRevalidations.delete(remote.name);
+        pendingRevalidation.resolve();
+      }
+    },
+  } satisfies Pick<ModuleFederationRuntimePlugin, "beforeRequest" | "afterLoadRemote">;
+
+  function getLastLoadedAt(origin: ModuleFederation) {
+    let lastLoadedAt = lastLoadedAtByOrigin.get(origin);
+    if (!lastLoadedAt) {
+      lastLoadedAt = new Map();
+      lastLoadedAtByOrigin.set(origin, lastLoadedAt);
+    }
+    return lastLoadedAt;
+  }
+
+  function getPendingRevalidations(origin: ModuleFederation) {
+    let pendingRevalidations = pendingRevalidationsByOrigin.get(origin);
+    if (!pendingRevalidations) {
+      pendingRevalidations = new Map();
+      pendingRevalidationsByOrigin.set(origin, pendingRevalidations);
+    }
+    return pendingRevalidations;
+  }
+}
+
+interface PendingRevalidation {
+  promise: Promise<void>;
+  resolve: () => void;
+}
+
+function createPendingRevalidation(): PendingRevalidation {
+  let resolve = () => {};
+  const promise = new Promise<void>((complete) => {
+    resolve = complete;
+  });
+  return { promise, resolve };
+}
+
+function findRemote(origin: ModuleFederation, id: string) {
+  return origin.options.remotes.find((remote) => {
+    const names = [remote.name, remote.alias].filter(
+      (name): name is string => typeof name === "string",
+    );
+    return names.some((name) => id === name || id.startsWith(`${name}/`));
+  });
+}
+
+function invalidateRemote(
+  origin: ModuleFederation,
+  remote: ModuleFederation["options"]["remotes"][number],
+) {
+  if (
+    (remote.type === "module" || remote.type === "esm") &&
+    "entry" in remote &&
+    typeof remote.entry === "string"
+  ) {
+    viteLoaders.get(origin)?.revalidate?.(remote.entry);
+  }
+  origin.registerRemotes([{ ...remote }], { force: true });
+}
+
 /**
  * Vite remotes can import shared packages from node_modules instead of the share scope:
  * a Vite dev server's module runner externalizes them, and resolved imports in production

packages/tanstack/src/rsbuild.ts

@@ -5,6 +5,7 @@ import {
 } from "@module-federation/rsbuild-plugin";
 import type { RsbuildPlugin } from "@rsbuild/core";
 import { defaultShared, eagerShared, resolveShared } from "./shared";
+import type { NodeEntryLoaderOptions } from "./node-entry-loader";
 
 type ModuleFederationOverride = Partial<ModuleFederationOptions>;
 
@@ -21,6 +22,7 @@ type ServerFederationOptions =
       entryFilename?: string;
       environment?: string;
       forceCommonJsOutput?: boolean;
+      ssrEntryLoader?: NodeEntryLoaderOptions;
     });
 
 export type TanStackStartRsbuildModuleFederationOptions = {
@@ -96,6 +98,7 @@ export function tanstackStartModuleFederation({
     entryFilename,
     environment: serverEnvironment = "ssr",
     forceCommonJsOutput = true,
+    ssrEntryLoader,
     ...serverOverrides
   } = server === true ? {} : server;
 
@@ -129,7 +132,12 @@ export function tanstackStartModuleFederation({
         {
           ...withDefaults(hostOptions, eagerShared),
           manifest: false,
-          runtimePlugins: [...(hostOptions.runtimePlugins ?? []), NODE_ENTRY_LOADER],
+          runtimePlugins: [
+            ...(hostOptions.runtimePlugins ?? []),
+            ssrEntryLoader
+              ? [NODE_ENTRY_LOADER, Object.fromEntries(Object.entries(ssrEntryLoader))]
+              : NODE_ENTRY_LOADER,
+          ],
         },
         { environment: serverEnvironment, target: "node" },
       ),