miner_stale_hashes_total was recorded in the QUIC loop for every result whose
job id no longer matched, which is every cancelled search: 74% of all hashes
on benjy flagged as stale on the first hour of data. That is the loop's
notion of a stale *result*, not wasted work; the hashes were done while the
job was current.
The wasted work is the batch that completes after the job was superseded.
Record that in the engine at the cancellation check, per device and kernel,
and drop the loop-level accounting. Expect one batch per job switch.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CBgs2nSi4H2mdh8kD8vMX5
