fix(vue): preserve runtime props declarations in pages patchProps

packages/vue/src/plugin-pages.ts

@@ -11,6 +11,24 @@ import type { PageScanResult, StaticPageDataBuildOptions } from 'void/pages';
 const RENDERER_ID = 'virtual:void-pages-renderer';
 const CLIENT_ENTRY_ID = 'virtual:void-pages-client';
 
+/** Runtime helper injected into generated SSR and client page bundles. */
+const PATCH_PROPS_RUNTIME = `
+function hasRuntimePropsDeclaration(comp) {
+  const declared = comp.props;
+  if (declared == null) return false;
+  if (Array.isArray(declared)) return declared.length > 0;
+  if (typeof declared === "object") return Object.keys(declared).length > 0;
+  return false;
+}
+
+function patchProps(comp, props) {
+  if (hasRuntimePropsDeclaration(comp)) return;
+  if (comp.__voidPatched) return;
+  comp.props = Object.keys(props);
+  comp.__voidPatched = true;
+}
+`;
+
 export type PrefetchConfig = {
   hoverDelay?: number;
   cacheFor?: number | string | [string, string];
@@ -279,11 +297,7 @@ import { serializePageData } from "void/pages-server";
 
 ${generateComponentManifest(scan, pagesDir)}
 
-function patchProps(comp, props) {
-  if (comp.__voidPatched) return;
-  comp.props = Object.keys(props);
-  comp.__voidPatched = true;
-}
+${PATCH_PROPS_RUNTIME}
 
 export async function renderPage(pageObj, assetTags) {
   const PageComponent = (await components[pageObj.component]()).default;
@@ -354,11 +368,7 @@ const currentPageKey = ref(0);
 const routeUrl = ref(window.location.pathname + window.location.search + window.location.hash);
 const navigation = reactive(idleNavigationState());
 
-function patchProps(comp, props) {
-  if (comp.__voidPatched) return;
-  comp.props = Object.keys(props);
-  comp.__voidPatched = true;
-}
+${PATCH_PROPS_RUNTIME}
 
 function replaceRecord(target, source) {
   for (const key of Object.keys(target)) delete target[key];

packages/vue/test/unit/plugin-pages.test.ts

@@ -36,6 +36,37 @@ function writePage(relativePath: string, source: string): void {
   writeFileSync(full, source);
 }
 
+type PatchProps = (comp: Record<string, unknown>, props: Record<string, unknown>) => void;
+
+function extractPatchProps(moduleSource: string): PatchProps {
+  const marker = 'function hasRuntimePropsDeclaration';
+  const start = moduleSource.indexOf(marker);
+  if (start === -1) {
+    throw new Error('Expected patchProps runtime in generated module.');
+  }
+  const afterPatchProps = moduleSource.indexOf('function replaceRecord', start);
+  const exportRender = moduleSource.indexOf('export async function renderPage', start);
+  const end = afterPatchProps === -1 ? exportRender : afterPatchProps;
+  if (end === -1) {
+    throw new Error('Expected patchProps runtime boundary in generated module.');
+  }
+  const block = moduleSource.slice(start, end);
+  return new Function(`${block}; return patchProps;`)() as PatchProps;
+}
+
+async function loadGeneratedPatchProps(
+  plugin: PagesPluginHooks,
+  virtualId: '\0virtual:void-pages-renderer' | '\0virtual:void-pages-client',
+): Promise<PatchProps> {
+  getHookHandler(plugin.config)({}, { command: 'build' });
+  await getHookHandler(plugin.buildStart).call({});
+  const source = await getHookHandler(plugin.load)(virtualId);
+  if (!source) {
+    throw new Error(`Expected generated module for ${virtualId}.`);
+  }
+  return extractPatchProps(source);
+}
+
 function setupWatcher(plugin: PagesPluginHooks, logError = vi.fn(), invalidateModule = vi.fn()) {
   const handlers = new Map<string, Array<(path: string) => Promise<void> | void>>();
   plugin.configureServer?.({
@@ -54,6 +85,61 @@ function setupWatcher(plugin: PagesPluginHooks, logError = vi.fn(), invalidateMo
   return handlers;
 }
 
+describe('pagesPlugin generated patchProps', () => {
+  afterEach(() => {
+    rmSync(TMP, { recursive: true, force: true });
+  });
+
+  it('preserves runtime object props declarations in SSR and client bundles', async () => {
+    writePage('index.vue', '<template><h1>Home</h1></template>\n');
+
+    const plugin = pagesPlugin(PAGES_DIR).find((p) => p.name === 'void-vue:pages') as
+      | PagesPluginHooks
+      | undefined;
+    if (!plugin) {
+      throw new Error('Expected void-vue:pages plugin.');
+    }
+
+    const rendererPatchProps = await loadGeneratedPatchProps(
+      plugin,
+      '\0virtual:void-pages-renderer',
+    );
+    const clientPatchProps = await loadGeneratedPatchProps(plugin, '\0virtual:void-pages-client');
+
+    const declared = {
+      title: { type: String, default: 'DEFAULT' },
+      count: { type: Number, required: true },
+    };
+    const comp: Record<string, unknown> = { props: { ...declared } };
+
+    rendererPatchProps(comp, { count: -1 });
+    expect(comp.props).toEqual(declared);
+    expect(comp.__voidPatched).toBeUndefined();
+
+    clientPatchProps(comp, { count: -1 });
+    expect(comp.props).toEqual(declared);
+    expect(comp.__voidPatched).toBeUndefined();
+  });
+
+  it('registers prop keys when the component has no runtime props declaration', async () => {
+    writePage('index.vue', '<template><h1>Home</h1></template>\n');
+
+    const plugin = pagesPlugin(PAGES_DIR).find((p) => p.name === 'void-vue:pages') as
+      | PagesPluginHooks
+      | undefined;
+    if (!plugin) {
+      throw new Error('Expected void-vue:pages plugin.');
+    }
+
+    const patchProps = await loadGeneratedPatchProps(plugin, '\0virtual:void-pages-renderer');
+    const comp: Record<string, unknown> = {};
+
+    patchProps(comp, { count: 1, title: 'hi' });
+    expect(comp.props).toEqual(['count', 'title']);
+    expect(comp.__voidPatched).toBe(true);
+  });
+});
+
 describe('pagesPlugin dev HMR', () => {
   afterEach(() => {
     rmSync(TMP, { recursive: true, force: true });