`ShareSeoController.getShare` resolved the inherited share with the RAW
`getShareForPage`, which does NOT run the restricted-ancestor gate. So for a
page shared with includeSubPages whose descendant is permission-restricted, the
SEO route served that descendant's real title in <title>/og:title/twitter:title
to anonymous visitors and crawlers — even though the content API returns 404 for
it (red-team finding #3).
Funnel the SEO path through the canonical `resolveReadableSharePage` boundary
(the single place that checks `hasRestrictedAncestor`): a non-readable page now
serves the plain SPA index with no meta. Also honour `isSharingAllowed` — a
share whose workspace/space sharing toggle was flipped off after creation no
longer leaks its title via SEO. Title comes from the server-resolved page;
`buildShareMetaHtml` already emits robots=noindex when the share opted out of
indexing.
Tests (controller routing, fs spied at call time so bcrypt's native loader is
untouched): non-readable page => plain index, no title; sharing-disabled =>
plain index; readable+indexing => title + og:title, no noindex; readable+no-
indexing => noindex. Asserts getShareForPage is never called by the SEO path.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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