diff --git a/data/sql/100_fix_mv_layout_velocity_weighted_avg.sql b/data/sql/100_fix_mv_layout_velocity_weighted_avg.sql
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+-- 100_fix_mv_layout_velocity_weighted_avg.sql
+-- SF Bug #21 (P0) — mv_layout_velocity использовал unweighted AVG() по
+-- deals_total_avg_area_m2 и deals_total_avg_price_thousand_rub_per_m2.
+-- objective_corpus_room_month хранит строки за каждый (project, room, month)
+-- включая месяцы с 0 сделок (count=0, area=0, price=0). Нули тянули
+-- среднее вниз в 2-14×. Примеры (verified prod):
+--   obj 65307, room=3: 114 месяцев, 106 нулевых → AVG=7.4 м² vs weighted=105.8 м²
+--   obj 65903, room=4+: 36 мес, 33 нулевых  → AVG=9.1 м² vs weighted=109.0 м²
+--
+-- Fix: заменяем AVG(x) на SUM(x * count) / NULLIF(SUM(count), 0) — weighted average.
+--
+-- Dependencies: mv_layout_velocity не имеет зависимых VIEW/MV (проверено 2026-05-17).
+-- Existing indexes: mv_layout_velocity_pk (UNIQUE obj_id, room_bucket),
+--                   mv_layout_velocity_obj_idx (obj_id) — пересоздаются ниже.
+--
+-- ВАЖНО: этот файл выполняет DROP + CREATE + REFRESH (non-concurrent, блокировка ~30 с).
+-- REFRESH CONCURRENTLY после первого populate — безопасен через layout_velocity_refresh.py.
+--
+-- Deploy order: SQL migration → app deploy (никаких backend изменений в этом PR).
+-- Idempotency: DROP IF EXISTS → безопасен при повторном запуске.
+
+BEGIN;
+
+DROP MATERIALIZED VIEW IF EXISTS mv_layout_velocity CASCADE;
+
+CREATE MATERIALIZED VIEW mv_layout_velocity AS
+WITH last24mo AS (
+    SELECT
+        ocm.project_name,
+        CASE
+            WHEN ocm.room_bucket = 'студия' THEN 'studio'
+            ELSE ocm.room_bucket
+        END                                                      AS room_bucket,
+        ocm.deals_total_count,
+        ocm.deals_total_avg_area_m2,
+        ocm.deals_total_avg_price_thousand_rub_per_m2,
+        ocm.deals_total_vol_m2,
+        ocm.report_month
+    FROM objective_corpus_room_month ocm
+    WHERE ocm.report_month >= (NOW() - INTERVAL '24 months')::date
+)
+SELECT
+    cm.domrf_obj_id                                              AS obj_id,
+    l.room_bucket,
+    SUM(l.deals_total_count)::int                               AS total_deals_24mo,
+
+    -- FIX SF #21: weighted average — нули из месяцев без сделок не тянут вниз.
+    -- Формула: SUM(avg_x * count) / SUM(count) эквивалентна SUM(total_x) / SUM(count),
+    -- т.к. avg_x = total_x / count за один месяц → произведение восстанавливает total_x.
+    (SUM(l.deals_total_avg_area_m2 * l.deals_total_count)
+        / NULLIF(SUM(l.deals_total_count), 0))::numeric(10, 2) AS avg_area_m2,
+
+    (SUM(l.deals_total_avg_price_thousand_rub_per_m2 * l.deals_total_count)
+        / NULLIF(SUM(l.deals_total_count), 0))::numeric(12, 2) AS avg_price_thousand_rub_per_m2,
+
+    SUM(l.deals_total_vol_m2)::numeric(12, 2)                  AS total_vol_m2,
+    MIN(l.report_month)                                         AS window_start,
+    MAX(l.report_month)                                         AS window_end,
+    COUNT(DISTINCT l.report_month)::int                         AS months_with_data
+FROM last24mo l
+JOIN objective_complex_mapping cm
+    ON cm.objective_complex_name = l.project_name
+WHERE l.room_bucket IS NOT NULL
+  AND cm.domrf_obj_id IS NOT NULL
+  AND cm.objective_group = 'Екатеринбург'
+GROUP BY cm.domrf_obj_id, l.room_bucket
+WITH NO DATA;
+
+-- UNIQUE index: required for REFRESH CONCURRENTLY (periodic via layout_velocity_refresh.py).
+-- GROUP BY (obj_id, room_bucket) guarantees uniqueness.
+CREATE UNIQUE INDEX mv_layout_velocity_pk
+    ON mv_layout_velocity (obj_id, room_bucket);
+
+-- Lookup index for /best-layouts endpoint queries by obj_id.
+CREATE INDEX mv_layout_velocity_obj_idx
+    ON mv_layout_velocity (obj_id);
+
+-- Initial populate (non-concurrent — MV just created, CONCURRENTLY requires populated MV).
+-- Блокировка ~30 с на production при ~19 738 source rows.
+REFRESH MATERIALIZED VIEW mv_layout_velocity;
+
+COMMENT ON MATERIALIZED VIEW mv_layout_velocity IS
+    'Per-(obj_id, room_bucket) deals aggregation за last 24 months. '
+    'WEIGHTED average площади и цены (SF Bug #21 fix, 2026-05-17). '
+    'Source: objective_corpus_room_month × objective_complex_mapping (EKB only). '
+    'Refresh via layout_velocity_refresh.py (CONCURRENTLY после initial populate).';
+
+COMMIT;