nitrojs · pi0 · Feb 23, 2026 · Feb 13, 2026 · Feb 19, 2026 · Feb 23, 2026
@@ -238,31 +238,36 @@ function nitroMain(ctx: NitroPluginContext): VitePlugin {
       return configureViteDevServer(ctx, server);
     },
 
-    // Automatically reload the client when a server module is updated
+    // Invalidate server-only modules and optionally reload the browser
     // see: https://github.com/vitejs/vite/issues/19114
     async hotUpdate({ server, modules, timestamp }) {
+      if (ctx.pluginConfig.experimental?.vite?.serverReload === false) {
+        return;
+      }
       const env = this.environment;
-      if (
-        ctx.pluginConfig.experimental?.vite.serverReload === false ||
-        env.config.consumer === "client"
-      ) {
+      if (env.config.consumer === "client") {
         return;
       }
       const clientEnvs = Object.values(server.environments).filter(
         (env) => env.config.consumer === "client"
       );
-      let hasServerOnlyModule = false;
+      const serverOnlyModules: EnvironmentModuleNode[] = [];
+      const sharedModules: EnvironmentModuleNode[] = [];
       const invalidated = new Set<EnvironmentModuleNode>();
       for (const mod of modules) {
         if (mod.id && !clientEnvs.some((env) => env.moduleGraph.getModuleById(mod.id!))) {
-          hasServerOnlyModule = true;
+          serverOnlyModules.push(mod);
           env.moduleGraph.invalidateModule(mod, invalidated, timestamp, false);
+        } else {
+          sharedModules.push(mod);
         }
       }
-      if (hasServerOnlyModule) {
+      if (serverOnlyModules.length > 0) {
         env.hot.send({ type: "full-reload" });
-        server.ws.send({ type: "full-reload" });
-        return [];
+        if (sharedModules.length === 0 && serverOnlyModules.some((m) => m.environment !== "ssr")) {
+          server.ws.send({ type: "full-reload" });
+        }
+        return sharedModules;
       }
     },
   };

@@ -30,7 +30,8 @@ export interface NitroPluginConfig extends NitroConfig {
       assetsImport?: boolean;
 
       /**
-       * Reload the page when a server module is updated.
+       *
+       * Invalidate server-only modules and optionally reload the browser when a server-only module is updated.
        *
        * @default true
        */

@@ -0,0 +1,3 @@
+import { state } from "../shared.ts";
+
+export default () => ({ state });
@@ -0,0 +1,3 @@
+import { state } from "../shared.ts";
+
+document.getElementById("client-state-value")!.textContent = state + " (modified)";
@@ -0,0 +1,26 @@
+import { html } from "nitro/h3";
+import { serverFetch } from "nitro";
+import { state } from "../shared.ts";
+
+export default {
+  fetch: async () => {
+    const apiData = (await serverFetch("/api/state").then((res) => res.json())) as {
+      state: number;
+    };
+    const viteClientScript = "<script type='module' src='/@vite/client'></script>";
+    const clientScript = "<script type='module' src='/app/entry-client.ts'></script>";
+    return html`
+    <!doctype html>
+    <html lang="en">
+      <head>${viteClientScript}</head>
+      <body>
+        <h1>SSR Page</h1>
+        <p>[SSR] state: ${state}</p>
+        <p>[API] state: ${apiData.state}</p>
+        <p id="client-state">[Client] state: <span id="client-state-value">?</span></p>
+        ${clientScript}
+      </body>
+    </html>
+  `;
+  },
+};
@@ -0,0 +1 @@
+export const state = 1;
@@ -0,0 +1,3 @@
+{
+  "extends": "nitro/tsconfig"
+}
@@ -0,0 +1,6 @@
+import { defineConfig } from "vite";
+import { nitro } from "nitro/vite";
+
+export default defineConfig({
+  plugins: [nitro({ serverDir: "./" })],
+});
@@ -0,0 +1,157 @@
+import { join } from "pathe";
+import { readFileSync, writeFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import type { ViteDevServer } from "vite";
+import { describe, test, expect, beforeAll, afterEach, afterAll } from "vitest";
+
+const { createServer } = (await import(
+  process.env.NITRO_VITE_PKG || "vite"
+)) as typeof import("vite");
+
+describe("vite:hmr", { sequential: true }, () => {
+  let server: ViteDevServer;
+  let serverURL: string;
+  const wsMessages: any[] = [];
+
+  const rootDir = fileURLToPath(new URL("./hmr-fixture", import.meta.url));
+
+  const files = {
+    client: openFileForEditing(join(rootDir, "app/entry-client.ts")),
+    api: openFileForEditing(join(rootDir, "api/state.ts")),
+    shared: openFileForEditing(join(rootDir, "shared.ts")),
+    ssr: openFileForEditing(join(rootDir, "app/entry-server.ts")),
+  };
+
+  beforeAll(async () => {
+    process.chdir(rootDir);
+    server = await createServer({ root: rootDir });
+
+    const originalSend = server.ws.send.bind(server.ws);
+    server.ws.send = function (payload: any) {
+      wsMessages.push(payload);
+      return originalSend(payload);
+    };
+
+    await server.listen("0" as unknown as number);
+    const addr = server.httpServer?.address() as { port: number; address: string; family: string };
+    serverURL = `http://${addr.family === "IPv6" ? `[${addr.address}]` : addr.address}:${addr.port}`;
+
+    const html = await fetch(serverURL).then((r) => r.text());
+    expect(html).toContain("<h1>SSR Page</h1>");
+    expect(html).toContain("[SSR] state: 1");
+    expect(html).toContain("[API] state: 1");
+  }, 30_000);
+
+  afterAll(async () => {
+    await server?.close();
+  });
+
+  afterEach(async () => {
+    wsMessages.length = 0;
+    let restored = false;
+    for (const file of Object.values(files)) {
+      if (file.restore()) {
+        restored = true;
+      }
+    }
+    if (restored) {
+      await waitFor(() => wsMessages.length > 0, 500);
+    }
+    wsMessages.length = 0;
+  });
+
+  test("editing API entry", async () => {
+    files.api.update((content) =>
+      content.replace("({ state })", '({ state: state + " (modified)" })')
+    );
+    await pollResponse(`${serverURL}/api/state`, /modified/);
+    expect(wsMessages).toMatchObject([{ type: "full-reload" }]);
+  });
+
+  test("Editing client entry (no full-reload)", async () => {
+    files.client.update((content) => content.replace(`+ ""`, `+ " (modified)"`));
+    await pollResponse(`${serverURL}/app/entry-client.ts`, /modified/);
+    expect(wsMessages.length).toBe(0);
+  });
+
+  test("editing SSR entry (no full-reload)", async () => {
+    files.ssr.update((content) =>
+      content.replace("<h1>SSR Page</h1>", "<h1>Modified SSR Page</h1>")
+    );
+    await pollResponse(serverURL, /Modified SSR Page/);
+    expect(wsMessages.length).toBe(0);
+  });
+
+  test("Editing shared entry", async () => {
+    files.shared.update((content) => content.replace(`state = 1`, `state = 2`));
+    await pollResponse(
+      `${serverURL}`,
+      (txt) => txt.includes("state: 2") && !txt.includes("state: 1")
+    );
+    expect(wsMessages).toMatchObject([{ type: "full-reload" }]);
+  });
+});
+
+function openFileForEditing(path: string) {
+  const originalContent = readFileSync(path, "utf-8");
+  return {
+    path,
+    update(cb: (content: string) => string) {
+      const currentContent = readFileSync(path, "utf-8");
+      const newContent = cb(currentContent);
+      writeFileSync(path, newContent);
+    },
+    restore() {
+      if (readFileSync(path, "utf-8") !== originalContent) {
+        writeFileSync(path, originalContent);
+        return true;
+      }
+      return false;
+    },
+  };
+}
+
+function waitFor(check: () => boolean, duration: number): Promise<void> {
+  const start = Date.now();
+  return new Promise((resolve) => {
+    const poll = () => {
+      if (check() || Date.now() - start > duration) {
+        resolve();
+      } else {
+        setTimeout(poll, 10);
+      }
+    };
+    poll();
+  });
+}
+
+function pollResponse(
+  url: string,
+  match: RegExp | ((txt: string) => boolean),
+  timeout = 5000
+): Promise<string> {
+  const start = Date.now();
+  let lastResponse = "";
+  return new Promise((resolve, reject) => {
+    const check = async () => {
+      try {
+        const response = await fetch(url);
+        lastResponse = await response.text();
+        if (typeof match === "function" ? match(lastResponse) : match.test(lastResponse)) {
+          resolve(lastResponse);
+        } else if (Date.now() - start > timeout) {
+          reject(
+            new Error(
+              `Timeout waiting for response to match ${match} at ${url}. Last response: ${lastResponse}`
+            )
+          );
+        } else {
+          setTimeout(check, 100);
+        }
+      } catch (err) {
+        reject(err);
+      }
+    };
+    check();
+  });
+}
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		import { state } from "../shared.ts";

		export default () => ({ state });
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		import { state } from "../shared.ts";

		document.getElementById("client-state-value")!.textContent = state + " (modified)";