webfetch.Fetcher.last held one entry per distinct host the crawler ever
dialed, never pruned. Bounded in practice by how many hosts get crawled, but
crawl.on_demand is true in deploy, so the host set is whatever he names out
loud.
An entry older than HostInterval cannot delay a request — waitTurn would let
the next one straight through — so it is dropped. The sweep runs on write and
only once the map passes 64 entries, below which walking it costs more than
the entries do.
Rate limiting is unchanged: a host dialed inside the interval is kept, which
the test asserts, because pruning one would hand out a free turn.
claude
4be6852b94