docs site: no `metadataBase` and no canonical link on any page

[os-zhuang]

One-liner

Not one page on the site emits <link rel="canonical">, and the root layout sets no metadataBase. Every URL variant of a page — query strings, tracking parameters, the /en/ prefixed form — is a separate document to a search engine, with nothing declaring which one is real.

Measured

$ grep -rn "metadataBase\|canonical\|alternates" apps/docs --include=*.ts --include=*.tsx | grep -v node_modules
(no matches)
$ curl -s http://localhost:3999/docs/data-modeling/objects | grep -c 'rel="canonical"'
0

Without metadataBase, any relative URL handed to openGraph/alternates resolves against a build-time guess rather than the real origin — which is why it must land before, or with, the Open Graph card.

Expected

• apps/docs/app/layout.tsx: metadataBase: new URL('https://objectstack.ai'), from the same shared origin constant the sitemap uses.
• apps/docs/app/[lang]/docs/[[...slug]]/page.tsx generateMetadata: alternates: { canonical: page.url }.
• Same for the homepage, the blog index and blog posts.

Acceptance

• every page type emits exactly one <link rel="canonical">, absolute, on https://objectstack.ai
• /docs/x?utm_source=y and /docs/x both canonicalise to /docs/x
• the Next build no longer warns about a missing metadataBase

Source

Found in an SEO review of the docs site (apps/docs) run on 2026-08-25, measured against the local dev server and against production. The canonical origin is https://objectstack.ai — maintainer ruling recorded in #10659:

这个仓的文档站规范 URL 是 https://objectstack.ai

[os-zhuang]

Held for round 2 — serial, not blocked. This card imports the shared origin constant that #12232 (dispatched now) owns creating; dispatching both at once means two agents creating the same file. Known trap to carry into the dispatch: read what #12232 actually exported before writing the import, and do not re-create the constant if it is already on main by then. #12235 is queued behind this card because it edits the same generateMetadata block.

[os-zhuang]

⚠️ Trap carried in from #12232's dev report — read before starting this card.

apps/docs/app/page.tsx is a shadowed route: proxy.ts rewrites / to /en, so RootPage() never runs (measured: curl / returns 200 text/html, not the 307 that file would produce). Filed standalone as #12255.

What it means here: the homepage's real metadata lives in apps/docs/app/[lang]/page.tsx. An agent that adds metadataBase or a canonical link to app/page.tsx will ship a green PR that changes nothing served. Verify against a rendered response, not against the file you edited.

The epic does not depend on #12255 being fixed — it stays a standalone finding — but this card does depend on knowing about it.