fix: avoid duplicate client HMR updates

contributors.yml

@@ -493,6 +493,7 @@
 - vladinator1000
 - vonagam
 - WalkAlone0325
+- wanxiankai
 - whxhlgy
 - wilcoxmd
 - willemarcel

integration/vite-hmr-hdr-test.ts

@@ -26,6 +26,11 @@ templates.forEach((template) => {
           // imports
           import { useState, useEffect } from "react";
 
+          if (typeof window !== "undefined") {
+            const global = window as typeof window & { __routeEvaluations?: number };
+            global.__routeEvaluations = (global.__routeEvaluations ?? 0) + 1;
+          }
+
           export const meta = () => [{ title: "HMR updated title: 0" }]
 
           // loader
@@ -170,6 +175,15 @@ async function workflow({
 
   await expect(page).toHaveTitle("HMR updated title: 0");
   await expect(hmrStatus).toHaveText("HMR updated: 0");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        () =>
+          (window as typeof window & { __routeEvaluations?: number })
+            .__routeEvaluations,
+      ),
+    )
+    .toBe(1);
   let input = page.locator("#index input");
   await expect(input).toBeVisible();
   await input.fill("stateful");
@@ -187,6 +201,14 @@ async function workflow({
   await expect(page).toHaveTitle("HMR updated title: 1");
   await expect(hmrStatus).toHaveText("HMR updated: 1");
   await expect(input).toHaveValue("stateful");
+  await page.waitForTimeout(100);
+  expect(
+    await page.evaluate(
+      () =>
+        (window as typeof window & { __routeEvaluations?: number })
+          .__routeEvaluations,
+    ),
+  ).toBe(2);
   expect(page.errors).toEqual([]);
 
   // route: add loader

packages/react-router-dev/.changes/patch.avoid-duplicate-client-hmr.md

@@ -0,0 +1 @@
+Avoid duplicate client HMR updates when source modules change in development

packages/react-router-dev/vite/plugin.ts

@@ -2433,12 +2433,21 @@ export const reactRouterVitePlugin: ReactRouterVitePlugin = () => {
       // each other, so we need to manually trigger client HMR updates if server
       // code has changed.
       hotUpdate(this, { server, modules }) {
-        if (this.environment.name !== "ssr" && modules.length <= 0) {
+        if (this.environment.name !== "ssr" || modules.length <= 0) {
           return;
         }
 
-        let clientModules = modules.flatMap((mod) =>
-          getParentClientNodes(server.environments.client.moduleGraph, mod),
+        let clientModuleGraph = server.environments.client.moduleGraph;
+        let clientModules = new Set(
+          modules.flatMap((mod) => {
+            // Modules that exist in the client graph already receive Vite's
+            // native client HMR update. Only propagate changes from modules
+            // that are exclusive to the server graph.
+            if (mod.id && clientModuleGraph.getModuleById(mod.id)) {
+              return [];
+            }
+            return getParentClientNodes(clientModuleGraph, mod);
+          }),
         );
 
         for (let clientModule of clientModules) {