fix(landing): make the site indexable — blog shells, sitemap, robots, share card (#51)

Co-authored-by: Alice <alice@prismshadow.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/landing/scripts/site-routes.mjs

@@ -0,0 +1,75 @@
+/**
+ * The deployed site's public routes, derived from the same Markdown filenames the two
+ * routers read (landing: content/blog/<slug>.<lang>.md, docs: content/<slug>.<lang>.md).
+ *
+ * Two consumers share this list, and they have to agree: the landing postbuild writes
+ * one static shell per route (so GitHub Pages answers 200 instead of falling back to
+ * 404.html), and build-site.mjs writes sitemap.xml for the assembled tree. A route that
+ * gets a shell belongs in the sitemap, and a sitemap URL that has no shell is a 404.
+ */
+import { readdirSync, readFileSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+
+/** Production origin, no trailing slash. Override for a staging deploy. */
+export const SITE_ORIGIN = (process.env.SITE_ORIGIN ?? "https://penguin.ooo").replace(/\/+$/, "");
+
+/** Deploy subpath, no trailing slash ("" at the domain root, "/repo" under a Pages subpath). */
+export const BASE_PATH = (process.env.BASE_PATH ?? "/").replace(/\/+$/, "");
+
+/** Absolute URL for a site-root-relative route path. */
+export function absoluteUrl(route) {
+  return `${SITE_ORIGIN}${BASE_PATH}${route}`;
+}
+
+const HERE = dirname(fileURLToPath(import.meta.url));
+const BLOG_DIR = join(HERE, "..", "content", "blog");
+const DOCS_DIR = join(HERE, "..", "..", "docs", "content");
+
+/** `<slug>.<lang>.md` -> slug, deduplicated across the two languages, sorted. */
+function slugsIn(dir) {
+  const slugs = new Set();
+  for (const file of readdirSync(dir)) {
+    const slug = /^(.+)\.(zh|en)\.md$/.exec(file)?.[1];
+    if (slug !== undefined) slugs.add(slug);
+  }
+  return [...slugs].sort();
+}
+
+/** Newest `date:` in a post's frontmatter across its language variants, if any. */
+function newestDate(dir, slug) {
+  let newest;
+  for (const lang of ["en", "zh"]) {
+    let raw;
+    try {
+      raw = readFileSync(join(dir, `${slug}.${lang}.md`), "utf8");
+    } catch {
+      continue; // A post exists in one language only; the other is a legitimate miss.
+    }
+    const frontmatter = /^---\r?\n([\s\S]*?)\r?\n---/.exec(raw)?.[1] ?? "";
+    const date = /^date:\s*"?(\d{4}-\d{2}-\d{2})"?\s*$/m.exec(frontmatter)?.[1];
+    if (date !== undefined && (newest === undefined || date > newest)) newest = date;
+  }
+  return newest;
+}
+
+/**
+ * Routes served by the landing SPA. Trailing slashes are deliberate: Pages serves
+ * `<route>/index.html` and 301s the slashless form to it, so the slash form is the URL
+ * that actually answers 200 — the one canonical tags and the sitemap should name.
+ * The home page is excluded; Vite's own index.html already sits at the dist root.
+ */
+export function blogRoutes() {
+  return [
+    { route: "/blog/" },
+    ...slugsIn(BLOG_DIR).map((slug) => ({
+      route: `/blog/${slug}/`,
+      lastmod: newestDate(BLOG_DIR, slug),
+    })),
+  ];
+}
+
+/** Routes served by the docs SPA, whose own postbuild already writes their shells. */
+export function docsRoutes() {
+  return [{ route: "/docs/" }, ...slugsIn(DOCS_DIR).map((slug) => ({ route: `/docs/${slug}/` }))];
+}