The backend downloaded every missing dataset before listening, so a first
boot (or a newly added dataset) refused every request for a minute or more.
Snapshots already on disk now load before the listener opens and missing
ones download behind it. Meanwhile only routes reading still-missing data
answer 503 (never edge-cached): /api/maxmind, /api/asn-connectivity and
/api/service-status. An ASN Profile section whose data is still loading
answers 'error' on its own, and the connectivity graph client doesn't cache
a 503, so both recover once the data lands.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>