A disk-backed art cache (library-art-cache.json in the canonical host config dir) is the
source of truth read by all_games(), so the library list + launch-resolve never block on
the network. A host-lifetime background warmer (start_art_warmer, started in serve())
fetches uncached art OFF the hot path: GOG via the public no-auth api.gog.com product API,
Xbox via the unofficial no-auth displaycatalog (keyed by StoreId). Both best-effort
(protocol-relative URLs normalized to https; results cached even when empty so they aren't
re-fetched). The GOG + Xbox providers now read cached_art() (title-only until warmed).
Cross-platform (ureq blocking HTTP — no tokio on this path) so the fetch/parse code is
compiled + checked everywhere; a host whose stores all self-provide art (Steam CDN /
Heroic CDN / Lutris data: URLs) does no fetching. Dep: ureq (webpki roots, no system certs).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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