Path calculator conditions map was missing :latitude and
:best_duct_band_ghz. Scorer read them with bracket-notation so the
behaviour was defensively correct but we were leaving signal on the
floor:
- latitude: midpoint of src/dst so `score_season` picks up the right
latitude-based seasonal shift for northern vs southern paths
- best_duct_band_ghz: queried via new Weather.nearest_native_duct_ghz/3
at the midpoint so score_refractivity/4 applies the 1.15× boost
when a native-resolution duct supports the target band
Recalibrator.fit/1 was serialising ~10k per-contact HRRR lookups
(5000 positives + 5000 negatives, one Weather.find_nearest_hrrr each).
Parallelised both sides with Task.async_stream at 20 concurrency —
well under the prod db pool of 30. Cuts a band recalibration from
~minutes of query round-trips to seconds.
Graham McIntire
06feda7110