Held-out fit (n=2366 prod deals, 2026-06-27) of
log(actual_sold/expected_sold) ~ year + ln(area) gives a multiplicative
factor that corrects systematic mis-estimation by building era + unit size
(underestimates newer buildings, mis-handles large units).
factor = exp(b0 + b_year*(year-2000)/20 + b_larea*ln(area)), clamped
[0.75, 1.30]; applied to the expected_sold point BEFORE the calibrated PI
range block (so the range follows the corrected point). Headline/asking is
untouched. Gated behind estimate_hedonic_correction_enabled (OFF => exact
old behavior, proven by the regression gate).
Frozen baseline regenerated: overall expected_sold MAPE 18.63->14.24;
per-segment median_bias_pct moves toward 0 (бизнес -21.5->-9.2,
комфорт -8.0->-3.6, эконом 17.2->4.3); элит mildly better, no harm.
Tests that assert the exact ratio relation (expected_sold == headline x
ratio) hold the orthogonal hedonic layer OFF.
