A catalog item that had a copy on server A lost it from the detail page when a later refresh could not reach A: partial results expire after the negative TTL and the fresh wave replaced the cache as a unit, so A failing while B answered empty left nothing, with no evidence A had removed anything.
The cache now holds per-server answers with one invariant: a server's answer is replaced only by that server. Servers that failed or were cancelled keep their last-known copies, servers named in no set have left the account, and the failed set still passes through so the outage stays visible and the wave is retried.
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