fix: resolve current entry for dev HMR re-fetch in multi-entry mode

packages/static/e2e/fixture-multi-entry/src/entries.tsx

@@ -12,5 +12,10 @@ export default function getEntries(): EntryDefinition[] {
       root: () => import("./root"),
       app: () => import("./pages/About"),
     },
+    {
+      path: "hmr-test.html",
+      root: () => import("./root"),
+      app: () => import("./pages/HmrTest"),
+    },
   ];
 }

packages/static/e2e/fixture-multi-entry/src/pages/HmrTest.tsx

@@ -0,0 +1,9 @@
+export default function HmrTest() {
+  return (
+    <main>
+      <h1>HMR Test Page</h1>
+      <p data-testid="page-id">hmr-test</p>
+      <p data-testid="hmr-content">initial content</p>
+    </main>
+  );
+}

packages/static/e2e/tests-dev/multi-entry.spec.ts

@@ -1,4 +1,6 @@
 import { expect, test } from "@playwright/test";
+import { readFile, writeFile } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
 
 const htmlHeaders = { Accept: "text/html" };
 
@@ -76,3 +78,38 @@ test.describe("Multi-entry page rendering (dev server)", () => {
     expect(errors).toEqual([]);
   });
 });
+
+test.describe("Multi-entry HMR (dev server)", () => {
+  const hmrPagePath = fileURLToPath(
+    new URL("../fixture-multi-entry/src/pages/HmrTest.tsx", import.meta.url),
+  );
+
+  test("server code change re-renders the current non-first entry", async ({
+    page,
+  }) => {
+    const originalSource = await readFile(hmrPagePath, "utf-8");
+    try {
+      await page.goto("/hmr-test");
+      await expect(page.locator("h1")).toHaveText("HMR Test Page");
+      await expect(page.getByTestId("hmr-content")).toHaveText(
+        "initial content",
+      );
+
+      await writeFile(
+        hmrPagePath,
+        originalSource.replace("initial content", "updated content"),
+      );
+
+      // The edited content should appear via HMR without a page reload
+      await expect(page.getByTestId("hmr-content")).toHaveText(
+        "updated content",
+        { timeout: 15000 },
+      );
+      // The page must still show this entry's tree, not the first entry's
+      await expect(page.locator("h1")).toHaveText("HMR Test Page");
+      await expect(page.getByTestId("page-id")).toHaveText("hmr-test");
+    } finally {
+      await writeFile(hmrPagePath, originalSource);
+    }
+  });
+});

packages/static/src/client/entry.tsx

@@ -33,9 +33,12 @@ async function devMain() {
 
   // re-fetch RSC and trigger re-rendering
   async function fetchRscPayload() {
-    const payload = await createFromFetch<RscPayload>(
-      fetch(withBasePath(devMainRscPath)),
-    );
+    // Pass the current page path so the server re-renders the entry
+    // being viewed rather than the first entry
+    const rscUrl = `${withBasePath(devMainRscPath)}?path=${encodeURIComponent(
+      location.pathname,
+    )}`;
+    const payload = await createFromFetch<RscPayload>(fetch(rscUrl));
     setPayload(payload);
   }
 

packages/static/src/rsc/entry.tsx

@@ -48,6 +48,20 @@ function findEntryForUrlPath(
   return undefined;
 }
 
+/**
+ * Resolves the entry for a URL path, falling back to the index entry
+ * (SPA fallback) when no entry matches.
+ */
+function resolveEntryForUrlPath(
+  entries: EntryDefinition[],
+  urlPath: string,
+): EntryDefinition | undefined {
+  return (
+    findEntryForUrlPath(entries, urlPath) ??
+    entries.find((e) => e.path === "index.html" || e.path === "index.htm")
+  );
+}
+
 /**
  * Renders a single entry to an HTML response.
  */
@@ -139,14 +153,7 @@ export async function serveHTML(request: Request): Promise<Response> {
 
   const url = new URL(request.url);
   const urlPath = stripBasePath(url.pathname);
-  let entry = findEntryForUrlPath(entries, urlPath);
-
-  // SPA fallback: if no entry matched, fall back to index.html or index.htm entry
-  if (!entry) {
-    entry = entries.find(
-      (e) => e.path === "index.html" || e.path === "index.htm",
-    );
-  }
+  const entry = resolveEntryForUrlPath(entries, urlPath);
 
   if (!entry) {
     return new Response("Not Found", {
@@ -180,15 +187,20 @@ export async function serveRSC(request: Request): Promise<Response> {
   const pathname = stripBasePath(url.pathname);
   if (pathname === devMainRscPath) {
     // root RSC stream is requested (HMR re-fetch always sends full tree)
-    // For HMR, re-render the first entry (single-entry mode) or index.html entry
     const entriesStart = performance.now();
     const entries = await loadEntriesList();
     timings.push(`entries;dur=${performance.now() - entriesStart}`);
 
-    // Use the first entry for HMR re-fetch
-    const entry = entries[0];
+    // Re-render the entry for the page the client is currently viewing,
+    // passed as the `path` query parameter (with the same SPA fallback as
+    // serveHTML). Fall back to the first entry if no path was provided.
+    const pagePath = url.searchParams.get("path");
+    const entry =
+      pagePath !== null
+        ? resolveEntryForUrlPath(entries, stripBasePath(pagePath))
+        : entries[0];
     if (!entry) {
-      throw new ServeRSCError("No entries defined", 404);
+      throw new ServeRSCError("No entry found for HMR re-fetch", 404);
     }
 
     const resolveStart = performance.now();