KeelrLeek
6d6968e9b1
On 2026-07-28 `webservice.fanart.tv` answered every request normally while `assets.fanart.tv` refused TCP on both :443 and :80. The two are different machines, and the hero chain only ever asked the first one anything. Every gate in that chain tests whether a provider RETURNED URLS, never whether those URLs load. So Fanart.tv handed back its usual eight banners and four logos, `banners.is_empty()` was false, and the two fallbacks that exist for exactly this situation -- TheAudioDB, then Bing -- were both skipped. The page then fell back to a blown-up square portrait. The tell that this was a provider outage rather than a regression in the hero code is that it was artist-shaped: every artist Fanart.tv covers lost its hero, and the ones it does not cover (Tame Impala) were untouched. Worth recording that browsing fanart.tv proves nothing here -- that is a third host, on Cloudflare, and it was up throughout. The check is a one-byte ranged GET, so it is proof the host serves image bytes without pulling a 4K background to find out. Any HTTP answer counts as alive: a 404 on one image is not an outage, so only a transport failure or a 5xx marks a host dead. Cached per host for 5 minutes, which is long enough that a dead CDN costs one probe rather than one per artist, and short enough that the hero comes back within minutes of the host recovering -- no restart, no cache clearing. The probe races the page, hence the 3s ceiling. It has to be applied in three places, and the third is the one that is easy to miss: - Discovery, after Fanart and again after TheAudioDB, so an unreachable CDN reads downstream as "this provider had nothing" -- precisely the state the fallback chain already knows how to handle. - The persisted manifest, because a manifest outlives the CDN behind it. A stored answer short-circuits discovery entirely, so replaying one produces a hero that never loads AND no path to the fallback that would have worked. - The "keep previous banners as a floor" clause. Restoring unreachable banners would undo the whole point of falling through: discovery correctly dropped a dead CDN, and the floor would put it straight back. Note for the next time this looks like a renderer bug: a 1x1 hero canvas is a SYMPTOM, not the cause. It means no image ever decoded, so the GPU renderer never sized itself.