Vision took a crop from 5 ms to 25 ms, so re-reading the same package on every
attempt was the measured cause of the live coverage collapse: 789 -> 60 crops/s
at 8 workers, and 12/8/2/6 labels on the same clip at four pacings.
The reading is now cached on the track and later attempts re-run only the local
lane. Measured through the real server on add/image6.jpg:
saturated pool 15.9 -> 49.4 crops/s (8 workers, 64 crops)
per crop 142 -> 92 ms on a 300x400 crop
3 s clip, send 19.7 mean labels (15-24, unstable) -> 24.0 (23-25, stable)
12 s clip, send 48/131 -> 53/131; result pacing 53/134 -> 50/135
The 12 s numbers are within run-to-run noise; the short clip is where the
pacing sensitivity lived and it is now flat across pacings.
An empty read is not cached - a crop too small or too blurry to read says
nothing about the next one - and the cache is cleared with the rest of the
evidence on a method change or a drift relabel, so a reading never outlives the
product it described. The native crop lane skips OCR on the same rule.
Test: OCR runs once per track while the local lane keeps running. Disabling the
skip makes it fail 2 != 1. Suite 280 -> 281.
tngo
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