fix: make blog manifests timezone independent and validate PR builds

.github/workflows/site-checks.yml

@@ -0,0 +1,43 @@
+name: Site checks
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: site-checks-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  site-checks:
+    name: Blog manifest and site build
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10.3.0
+      - name: Set up Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: pnpm
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      - name: Test manifest generation across timezones
+        run: node --test scripts/generate-blog-manifests.test.mjs
+      - name: Check committed blog manifests
+        run: pnpm blog:manifest:check
+      - name: Build site
+        run: pnpm run build

scripts/generate-blog-manifests.mjs

@@ -55,7 +55,13 @@ function canonicalDate(value, field, sourceFile) {
   if (typeof value !== 'string' && !(value instanceof Date)) {
     throw new Error(`${sourceFile}: frontmatter field ${field} must be a date string`);
   }
-  const date = value instanceof Date ? value : new Date(value);
+  // English calendar dates have no timezone. Parse them in UTC so a manifest
+  // generated locally is identical to one checked by the deployment runner.
+  const dateInput = typeof value === 'string'
+    && /^[a-z]{3,9}\s+\d{1,2},?\s+\d{4}$/i.test(value.trim())
+    ? `${value.trim()} UTC`
+    : value;
+  const date = value instanceof Date ? value : new Date(dateInput);
   if (Number.isNaN(date.getTime())) {
     throw new Error(`${sourceFile}: frontmatter field ${field} is not a valid date`);
   }

scripts/generate-blog-manifests.test.mjs

@@ -0,0 +1,63 @@
+import assert from 'node:assert/strict';
+import { spawnSync } from 'node:child_process';
+import { copyFile, mkdir, mkdtemp, readFile, rm, symlink, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import test from 'node:test';
+
+const root = dirname(dirname(fileURLToPath(import.meta.url)));
+const timezones = ['UTC', 'Asia/Shanghai', 'America/Los_Angeles'];
+
+function generate(directory, mode, timezone) {
+  return spawnSync(process.execPath, [join(directory, 'scripts/generate-blog-manifests.mjs'), mode], {
+    cwd: directory,
+    env: { ...process.env, TZ: timezone },
+    encoding: 'utf8',
+  });
+}
+
+function succeeds(result) {
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+}
+
+test('committed manifests match article metadata in every supported timezone', () => {
+  for (const timezone of timezones) succeeds(generate(root, '--check', timezone));
+});
+
+test('calendar dates remain stable and stale metadata is rejected', async (t) => {
+  const fixture = await mkdtemp(join(tmpdir(), 'blog-manifest-'));
+  t.after(() => rm(fixture, { recursive: true, force: true }));
+  await mkdir(join(fixture, 'scripts'));
+  await copyFile(join(root, 'scripts/generate-blog-manifests.mjs'), join(fixture, 'scripts/generate-blog-manifests.mjs'));
+  await symlink(join(root, 'node_modules'), join(fixture, 'node_modules'), 'dir');
+  const article = `---
+title: Calendar date fixture
+description: A timezone regression fixture
+pubDate: Aug 9 2026
+updatedDate: 'Apr 07 2026'
+---
+Fixture body.
+`;
+  for (const locale of ['en', 'cn']) {
+    const directory = join(fixture, 'src/content/blog', locale);
+    await mkdir(directory, { recursive: true });
+    await writeFile(join(directory, 'calendar.md'), article);
+    await writeFile(join(directory, 'iso.md'), article.replace('Aug 9 2026', '2026-08-09').replace("'Apr 07 2026'", "'2026-04-07'"));
+    await writeFile(join(directory, 'draft.md'), article.replace('title:', 'draft: true\ntitle:'));
+  }
+  succeeds(generate(fixture, '--write', 'Asia/Shanghai'));
+  for (const timezone of timezones) succeeds(generate(fixture, '--check', timezone));
+  for (const locale of ['en', 'cn']) {
+    const manifest = JSON.parse(await readFile(join(fixture, 'src/content/blog', locale, 'posts.json'), 'utf8'));
+    assert.equal(manifest.posts.length, 2, 'drafts must stay excluded');
+    for (const post of manifest.posts) {
+      assert.equal(post.pubDate, '2026-08-09');
+      assert.equal(post.updatedAt, '2026-04-07');
+    }
+  }
+  await writeFile(join(fixture, 'src/content/blog/en/calendar.md'), article.replace('Calendar date fixture', 'Updated title'));
+  const stale = generate(fixture, '--check', 'UTC');
+  assert.equal(stale.status, 1);
+  assert.match(stale.stderr, /en\/posts\.json is stale/);
+});