`Scorer.aurora_boost(score, kp, band_config)` is a terminal boost
applied after `composite_score` in the same shape as the existing
`commercial_link_boost`. It tracks the NOAA G-scale (Kp 5+ opens
auroral E-region paths up to ~2500 km) and is freq-gated to
≤ 432 MHz — auroral propagation is observed almost exclusively on
50/144/222, occasionally on 432, and never at microwave.
Boost magnitudes:
* Kp < 4 (quiet) — pass-through
* Kp 4 — +5
* Kp 5 (G1) — +15
* Kp 6 (G2) — +25
* Kp ≥ 7 (G3+) — +35, clamped to 100
Wired into `Propagation.score_grid_point/4` via the existing
`hrrr_profile` map: callers populate `:kp_index` once per cycle so
the per-grid-point band loop never queries the DB. The UI fallback
path (`factors_from_profile/5`) sources Kp from
`SpaceWeather.latest_kp/0` directly. Other call sites
(GEFS forecast, path-compute, contact-show) can opt in by adding
`:kp_index` to their profile map.
Diagnostic factor `:kp_index` is stashed on VHF/low-UHF results so
the operator-facing factor breakdown can show why a band scored
above its quiet-conditions baseline. Microwave bands don't carry
the diagnostic — they're never affected by the boost.
Refactored `score_with_algorithm/7` to delegate band-level
finalization to `finalize_band_result/5`, keeping the parent
function under credo's cyclomatic-complexity limit.
NOTE: this only affects the Elixir scoring path — the live grid
served by `prop_grid_rs` (Rust) does its own scoring and does not
yet honor Kp. Adding aurora to the Rust side is follow-up work.
Graham McIntire
7702b9e161