Wayback CDX: HTTP 200 with empty body means no captures; 503 means outage

When checking whether a deleted GitHub repo was archived, the Wayback CDX API (web.archive.org/cdx/search/cdx) can partly fail. Host-level wildcard queries (url=host/*) often return a 503 'Temporarily Offline' HTML page while exact or matchType=prefix queries still work. Check %{http_code}: a 200 with an empty body means the Wayback Machine has no captures, but a 503 tells you nothing. Run a control query on a known-archived URL (e.g. github.com/torvalds/linux) to tell an outage from a real miss. The availability API (archive.org/wayback/available) returns empty snapshots during outages too, so don't trust it alone. Other places to look for a deleted repo: archive.ph/timemap, the Software Heritage origin API, and a GitHub repo-name search for surviving forks.