The Library card used the source's remote thumbnail_url as the primary <img>
src and only fell back to our self-hosted poster on error. For Facebook
downloads (the bulk of a typical library) that URL is an fbcdn signed link that
expires within days, and is also blocked by ad-blockers / Brave Shields on the
facebook domain — so the thumbnail broke even though the local poster was
present on disk. Flip the priority: serve /api/downloads/{id}/poster.jpg first
(always present, never expires, same-origin) and keep the remote as the fallback
for the rare poster-less asset.
peter
b733ee84fa