From f3a700f3083ed49fa93b8a4ba7649627d89c187c Mon Sep 17 00:00:00 2001
From: Shinya Fujino <shf0811@gmail.com>
Date: Tue, 3 Nov 2026 11:24:51 +0900
Subject: [PATCH] fix(md): run client scripts in builds without an .island.
 file

The Markdown client entry joined the client build only when a file with
`.island.` in its name existed under `pages/`. Without one, a page's
client script ran in dev but not after a production build, even when the
page imported an island.

Add the entry when a page the build keeps has client code, using the
same file list and script extraction as the Markdown page scan. A script
with only island imports, a `<script>` in a code block and a `.dev` page
no longer count. The old check also matched these, so an app with a
`.island.` file could build an empty entry that its pages with
JavaScript loaded.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J8F8maan2SAVMkNT2gaiUH
---
 packages/md/src/plugin.ts                     | 49 ++++-------
 .../integration/client-script-build.test.ts   | 82 +++++++++++++++++++
 .../md/test/unit/plugin-source-dir.test.ts    | 58 ++++++++++---
 3 files changed, 145 insertions(+), 44 deletions(-)
 create mode 100644 packages/md/test/integration/client-script-build.test.ts

diff --git a/packages/md/src/plugin.ts b/packages/md/src/plugin.ts
index 84b74ee8a..30699d528 100644
--- a/packages/md/src/plugin.ts
+++ b/packages/md/src/plugin.ts
@@ -1,5 +1,5 @@
 import { createHash } from 'node:crypto';
-import { existsSync, readFileSync, readdirSync } from 'node:fs';
+import { existsSync, readFileSync } from 'node:fs';
 import { dirname, join, relative, resolve } from 'pathslash';
 import { glob } from 'tinyglobby';
 import { normalizePath, type Plugin, type ResolvedConfig, type ViteDevServer } from 'vite';
@@ -57,32 +57,22 @@ function mdRouteName(file: string, env: 'dev' | 'prod' | null): string {
   return name.endsWith('/index') ? name.slice(0, -'/index'.length) : name;
 }
 
-function hasMdFilesWithScript(dir: string): boolean {
-  try {
-    for (const entry of readdirSync(dir, { withFileTypes: true, recursive: true })) {
-      if (entry.isFile() && entry.name.endsWith('.md')) {
-        const fullPath = join(entry.parentPath, entry.name);
-        const content = readFileSync(fullPath, 'utf-8');
-        if (/^<script\b/m.test(content)) {
-          return true;
-        }
-      }
-    }
-  } catch {
-    // ignore
-  }
-  return false;
+/** The Markdown files that `environment` keeps, relative to `pagesDir`. */
+async function listMdFiles(pagesDir: string, environment: 'dev' | 'prod'): Promise<Array<string>> {
+  const mdFiles = await glob('**/*.md', { cwd: pagesDir });
+  // Skip pages for the other environment, so their scripts are not added either.
+  return mdFiles.filter((file) => {
+    const fileEnv = pageFileEnvironment(file);
+    return !fileEnv || fileEnv === environment;
+  });
 }
 
-function hasIslandFiles(dir: string): boolean {
-  try {
-    for (const entry of readdirSync(dir, { withFileTypes: true, recursive: true })) {
-      if (entry.isFile() && /\.island\./.test(entry.name)) {
-        return true;
-      }
+/** Whether any page has client code. Without it, pages would load an empty client entry. */
+async function hasMdClientCode(pagesDir: string, environment: 'dev' | 'prod'): Promise<boolean> {
+  for (const file of await listMdFiles(pagesDir, environment)) {
+    if (extractScript(readFileSync(join(pagesDir, file), 'utf-8')).clientCode) {
+      return true;
     }
-  } catch {
-    // ignore
   }
   return false;
 }
@@ -114,12 +104,7 @@ export function voidMarkdown(options?: MarkdownOptions): Array<Plugin> {
       return [];
     }
 
-    const mdFiles = await glob('**/*.md', { cwd: pagesDir });
-    // Skip pages for the other environment, so their scripts are not added either.
-    const liveFiles = mdFiles.filter((file) => {
-      const fileEnv = pageFileEnvironment(file);
-      return !fileEnv || fileEnv === mdEnvironment;
-    });
+    const liveFiles = await listMdFiles(pagesDir, mdEnvironment);
     const pages = await Promise.all(
       liveFiles.map(async (file) => {
         const content = readFileSync(join(pagesDir, file), 'utf-8');
@@ -156,7 +141,7 @@ export function voidMarkdown(options?: MarkdownOptions): Array<Plugin> {
         },
       },
 
-      config(config, env) {
+      async config(config, env) {
         mdEnvironment = env.command === 'serve' && !env.isPreview ? 'dev' : 'prod';
         if (env.command === 'serve') {
           return;
@@ -166,7 +151,7 @@ export function voidMarkdown(options?: MarkdownOptions): Array<Plugin> {
         if (!existsSync(pagesDir)) {
           return;
         }
-        if (hasMdFilesWithScript(pagesDir) && hasIslandFiles(pagesDir)) {
+        if (await hasMdClientCode(pagesDir, mdEnvironment)) {
           return {
             environments: {
               client: {
diff --git a/packages/md/test/integration/client-script-build.test.ts b/packages/md/test/integration/client-script-build.test.ts
new file mode 100644
index 000000000..97d5e200b
--- /dev/null
+++ b/packages/md/test/integration/client-script-build.test.ts
@@ -0,0 +1,82 @@
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+import { chromium, type Browser } from 'playwright';
+import { preview, type PreviewServer } from 'vite';
+import { expect, it } from 'vite-plus/test';
+import { waitForIslandsHydrated } from '../../../../test/browser-helpers.ts';
+import { buildIslandApp } from '../../../../test/island-css-build.ts';
+
+it('runs client scripts in a production build with no .island. file in pages/', async () => {
+  const build = buildIslandApp({
+    packageDir: join(import.meta.dirname, '../../../react'),
+    pluginName: 'voidReact',
+    files: {
+      'tsconfig.json': JSON.stringify({ compilerOptions: { jsx: 'react-jsx' } }),
+      'components/Counter.island.tsx': `import { useState } from 'react';
+export default function Counter() {
+  const [count, setCount] = useState(0);
+  return <button onClick={() => setCount(count + 1)}>Count: {count}</button>;
+}`,
+      'pages/script.md': `<script>
+document.querySelector('#out').textContent = 'set-by-script';
+</script>
+
+# Script
+
+<span id="out">unset</span>
+`,
+      'pages/mixed.md': `<script>
+import Counter from '../components/Counter.island.tsx' with { island: 'load' };
+document.querySelector('#out').textContent = 'set-by-script';
+</script>
+
+# Mixed
+
+<span id="out">unset</span>
+
+<Counter />
+`,
+    },
+  });
+  let server: PreviewServer | undefined;
+  let browser: Browser | undefined;
+  try {
+    const manifest = JSON.parse(
+      readFileSync(join(build.root, 'dist/client/.vite/manifest.json'), 'utf8'),
+    );
+    expect(manifest).toHaveProperty(['virtual:void-md-client']);
+    // A page without client code still ships no JavaScript.
+    expect(build.page('about.html').html).not.toContain('<script');
+
+    server = await preview({
+      root: build.root,
+      configFile: false,
+      logLevel: 'silent',
+      build: { outDir: 'dist/client' },
+      preview: { host: '127.0.0.1', port: 0 },
+    });
+    const base = server.resolvedUrls?.local[0];
+    if (!base) {
+      throw new Error('Preview did not report a local URL.');
+    }
+    browser = await chromium.launch();
+    const page = await browser.newPage();
+    const errors: Array<string> = [];
+    page.on('pageerror', (error) => errors.push(error.message));
+
+    await page.goto(new URL('script', base).href);
+    await expect.poll(() => page.textContent('#out'), { timeout: 15_000 }).toBe('set-by-script');
+
+    await page.goto(new URL('mixed', base).href);
+    await expect.poll(() => page.textContent('#out'), { timeout: 15_000 }).toBe('set-by-script');
+    await waitForIslandsHydrated(page, 1, 15_000);
+    await page.getByRole('button', { name: 'Count: 0', exact: true }).click();
+    await expect.poll(() => page.getByRole('button').textContent()).toBe('Count: 1');
+
+    expect(errors).toEqual([]);
+  } finally {
+    await browser?.close();
+    await server?.close();
+    build.cleanup();
+  }
+}, 120_000);
diff --git a/packages/md/test/unit/plugin-source-dir.test.ts b/packages/md/test/unit/plugin-source-dir.test.ts
index 0ca6ebbce..5f1e413fc 100644
--- a/packages/md/test/unit/plugin-source-dir.test.ts
+++ b/packages/md/test/unit/plugin-source-dir.test.ts
@@ -77,7 +77,7 @@ describe('voidMarkdown sourceDir support', () => {
     const buildStart = getHookHandler(plugin.buildStart) as () => Promise<void>;
     const load = getHookHandler(plugin.load) as (id: string) => string | undefined;
 
-    config({ root }, { command });
+    await config({ root }, { command });
     configResolved({
       root,
       plugins: [{ name: 'void-react:pages' }],
@@ -121,21 +121,32 @@ describe('voidMarkdown sourceDir support', () => {
     expect((await scanForCommand(root, 'build')).paths).toEqual(['/posts/stats']);
   });
 
-  it('adds the markdown client entry for sourceDir pages with scripts and islands', () => {
+  function buildConfigFor(pages: Record<string, string>): Promise<unknown> {
     const root = createTempRoot();
-    writeFileSync(
-      join(root, 'src', 'pages', 'posts', 'hello.md'),
-      '<script>\ndocument.body.dataset.md = "ready";\n</script>\n\n# Hello\n',
-    );
-    writeFileSync(join(root, 'src', 'pages', 'posts', 'Counter.island.tsx'), 'export default {};');
-
-    const plugin = createPlugin();
-    const config = getHookHandler(plugin.config) as (
+    for (const [file, content] of Object.entries(pages)) {
+      writeFileSync(join(root, 'src', 'pages', file), content);
+    }
+    const config = getHookHandler(createPlugin().config) as (
       config: { root: string },
       env: { command: 'build' },
-    ) => unknown;
+    ) => Promise<unknown>;
+    return config({ root }, { command: 'build' });
+  }
 
-    expect(config({ root }, { command: 'build' })).toEqual({
+  const CLIENT_CODE = '<script>\ndocument.body.dataset.md = "ready";\n</script>\n\n# Hello\n';
+  const ISLAND_IMPORT = 'import Counter from "./Counter.tsx" with { island: "load" };';
+
+  it.each([
+    ['a page', { 'posts/hello.md': CLIENT_CODE }],
+    ['a build-only page', { 'stats.prod.md': CLIENT_CODE }],
+    [
+      'a page that also imports an island',
+      {
+        'mixed.md': `<script>\n${ISLAND_IMPORT}\nconsole.log("ready");\n</script>\n\n<Counter />\n`,
+      },
+    ],
+  ])('adds the markdown client entry for client code on %s', async (_name, pages) => {
+    expect(await buildConfigFor(pages)).toEqual({
       environments: {
         client: {
           build: {
@@ -147,4 +158,27 @@ describe('voidMarkdown sourceDir support', () => {
       },
     });
   });
+
+  it.each([
+    ['pages without a script', { 'hello.md': '# Hello\n' }],
+    [
+      'a script with only island imports',
+      { 'hello.md': `<script>\n${ISLAND_IMPORT}\n</script>\n\n<Counter />\n` },
+    ],
+    [
+      'a script tag in a code block',
+      { 'hello.md': '# Hello\n\n```html\n<script>\nconsole.log("example");\n</script>\n```\n' },
+    ],
+    ['client code on a dev-only page', { 'debug.dev.md': CLIENT_CODE, 'hello.md': '# Hello\n' }],
+    [
+      'island files next to pages without client code',
+      {
+        'hello.md': `<script>\n${ISLAND_IMPORT}\n</script>\n\n<Counter />\n`,
+        'Counter.island.tsx': 'export default {};',
+        '_x.island.txt': '',
+      },
+    ],
+  ])('does not add the markdown client entry for %s', async (_name, pages) => {
+    expect(await buildConfigFor(pages)).toBeUndefined();
+  });
 });