diff --git a/tradein-mvp/backend/app/services/estimator.py b/tradein-mvp/backend/app/services/estimator.py
index dd88aebf..c2fb473a 100644
--- a/tradein-mvp/backend/app/services/estimator.py
+++ b/tradein-mvp/backend/app/services/estimator.py
@@ -3348,23 +3348,27 @@ def _fetch_price_trend(
     # #audit-3: freshness_months — фильтр по scraped_at чтобы исключить стale items
     # (yandex_valuation из 2024 и т.д.). Применяется ко ВСЕМ source в этом запросе
     # (avito_imv + yandex_valuation), не только к yandex_valuation. Дефолт из config.
+    # Mera-audit fix-3: cross-source dedup за флагом estimate_price_trend_dedup_enabled.
     _fresh_months = freshness_months if freshness_months is not None else months
+    _dedup_enabled = settings.estimate_price_trend_dedup_enabled
     try:
-        rows = (
-            db.execute(
-                text(
-                    """
-                    SELECT to_char(
-                               date_trunc('month',
-                                          COALESCE(last_price_date, start_price_date)),
-                               'YYYY-MM'
-                           ) AS month,
-                           round(
-                               percentile_cont(0.5) WITHIN GROUP (
-                                   ORDER BY COALESCE(last_price, start_price)
-                                            / NULLIF(area_m2, 0)
-                               )
-                           )::int AS ppm2
+        if _dedup_enabled:
+            # Дедупликация near-дублей: один объект на avito_imv + yandex_valuation
+            # c разными ext_item_id → double-count в медиане. DISTINCT ON по ключу
+            # (round(area_m2,0), floor, price, price_date) с приоритетом avito_imv
+            # (source='avito_imv' сортируется раньше через CASE).
+            trend_sql = """
+                WITH deduped AS (
+                    SELECT DISTINCT ON (
+                               ROUND(area_m2),
+                               floor,
+                               COALESCE(last_price, start_price),
+                               COALESCE(last_price_date, start_price_date)
+                           )
+                           area_m2,
+                           floor,
+                           COALESCE(last_price, start_price)   AS price,
+                           COALESCE(last_price_date, start_price_date) AS price_date
                     FROM house_placement_history
                     WHERE house_id = CAST(:hid AS bigint)
                       AND area_m2 > 0
@@ -3375,10 +3379,53 @@ def _fetch_price_trend(
                       AND scraped_at > (now()
                           - CAST(:fresh_months AS integer)
                           * CAST('1 month' AS interval))
-                    GROUP BY 1
-                    ORDER BY 1 ASC
-                    """
-                ),
+                    ORDER BY
+                        ROUND(area_m2),
+                        floor,
+                        COALESCE(last_price, start_price),
+                        COALESCE(last_price_date, start_price_date),
+                        CASE source WHEN 'avito_imv' THEN 0 ELSE 1 END ASC,
+                        scraped_at DESC
+                )
+                SELECT to_char(date_trunc('month', price_date), 'YYYY-MM') AS month,
+                       round(
+                           percentile_cont(0.5) WITHIN GROUP (
+                               ORDER BY price / NULLIF(area_m2, 0)
+                           )
+                       )::int AS ppm2
+                FROM deduped
+                GROUP BY 1
+                ORDER BY 1 ASC
+            """
+        else:
+            trend_sql = """
+                SELECT to_char(
+                           date_trunc('month',
+                                      COALESCE(last_price_date, start_price_date)),
+                           'YYYY-MM'
+                       ) AS month,
+                       round(
+                           percentile_cont(0.5) WITHIN GROUP (
+                               ORDER BY COALESCE(last_price, start_price)
+                                        / NULLIF(area_m2, 0)
+                           )
+                       )::int AS ppm2
+                FROM house_placement_history
+                WHERE house_id = CAST(:hid AS bigint)
+                  AND area_m2 > 0
+                  AND COALESCE(last_price, start_price) > 0
+                  AND COALESCE(last_price_date, start_price_date) IS NOT NULL
+                  AND COALESCE(last_price_date, start_price_date) > (CURRENT_DATE
+                      - (CAST(:months AS integer) || ' months')::interval)
+                  AND scraped_at > (now()
+                      - CAST(:fresh_months AS integer)
+                      * CAST('1 month' AS interval))
+                GROUP BY 1
+                ORDER BY 1 ASC
+            """
+        rows = (
+            db.execute(
+                text(trend_sql),
                 {"hid": target_house_id, "months": months, "fresh_months": _fresh_months},
             )
             .mappings()
diff --git a/tradein-mvp/backend/tests/test_estimator_price_trend_dedup.py b/tradein-mvp/backend/tests/test_estimator_price_trend_dedup.py
new file mode 100644
index 00000000..090ac101
--- /dev/null
+++ b/tradein-mvp/backend/tests/test_estimator_price_trend_dedup.py
@@ -0,0 +1,147 @@
+"""Mera-audit fix-3: cross-source dedup в _fetch_price_trend.
+
+Проверяет что при dedup_enabled=True один объект на avito_imv + yandex_valuation
+с разными ext_item_id не double-count'ится в месячной медиане.
+"""
+
+from __future__ import annotations
+
+import os
+from typing import Any
+from unittest.mock import MagicMock, patch
+
+os.environ.setdefault("DATABASE_URL", "postgresql+psycopg://test:test@localhost/test_db")
+
+import pytest
+
+from app.services.estimator import _fetch_price_trend
+
+
+def _make_mock_db(source1_rows: list[dict], source2_rows: list[dict]) -> MagicMock:
+    """Возвращает mock db: Source1 (houses_price_dynamics) → source1_rows,
+    Source2 (house_placement_history) → source2_rows."""
+    mock_db = MagicMock()
+
+    def side_effect(*args: Any, **kwargs: Any) -> MagicMock:
+        call_text = str(args[0].text) if args else ""
+        result = MagicMock()
+        if "houses_price_dynamics" in call_text:
+            result.mappings.return_value.all.return_value = source1_rows
+        else:
+            result.mappings.return_value.all.return_value = source2_rows
+        return result
+
+    mock_db.execute.side_effect = side_effect
+    return mock_db
+
+
+# ---------------------------------------------------------------------------
+# Fix-3: dedup enabled (default True)
+# ---------------------------------------------------------------------------
+
+
+def test_dedup_enabled_flag_is_true_by_default() -> None:
+    """estimate_price_trend_dedup_enabled дефолт True."""
+    from app.core.config import settings
+
+    assert settings.estimate_price_trend_dedup_enabled is True
+
+
+def test_price_trend_dedup_sql_uses_distinct_on_when_enabled() -> None:
+    """Когда dedup включён, SQL-запрос к house_placement_history содержит DISTINCT ON."""
+    mock_db = _make_mock_db([], [{"month": "2026-01", "ppm2": 150_000}])
+
+    with patch("app.services.estimator.settings") as mock_settings:
+        mock_settings.estimate_price_trend_dedup_enabled = True
+        mock_settings.estimate_price_trend_max_age_months = 6
+
+        _fetch_price_trend(mock_db, target_house_id=42, min_points=1)
+
+    calls = mock_db.execute.call_args_list
+    # Второй вызов — Source 2 (house_placement_history)
+    assert len(calls) >= 2
+    second_sql = str(calls[1].args[0].text) if calls[1].args else ""
+    assert "DISTINCT ON" in second_sql.upper() or "distinct on" in second_sql.lower()
+
+
+def test_price_trend_dedup_disabled_no_distinct_on() -> None:
+    """Когда dedup выключен, SQL НЕ содержит DISTINCT ON (legacy path)."""
+    mock_db = _make_mock_db([], [{"month": "2026-01", "ppm2": 150_000}])
+
+    with patch("app.services.estimator.settings") as mock_settings:
+        mock_settings.estimate_price_trend_dedup_enabled = False
+        mock_settings.estimate_price_trend_max_age_months = 6
+
+        _fetch_price_trend(mock_db, target_house_id=42, min_points=1)
+
+    calls = mock_db.execute.call_args_list
+    assert len(calls) >= 2
+    second_sql = str(calls[1].args[0].text) if calls[1].args else ""
+    assert "distinct on" not in second_sql.lower()
+
+
+def test_price_trend_returns_result_with_dedup_enabled() -> None:
+    """Функция корректно возвращает точки тренда при dedup_enabled=True."""
+    rows = [
+        {"month": "2025-11", "ppm2": 148_000},
+        {"month": "2025-12", "ppm2": 152_000},
+        {"month": "2026-01", "ppm2": 155_000},
+    ]
+    mock_db = _make_mock_db([], rows)
+
+    with patch("app.services.estimator.settings") as mock_settings:
+        mock_settings.estimate_price_trend_dedup_enabled = True
+        mock_settings.estimate_price_trend_max_age_months = 6
+
+        result = _fetch_price_trend(mock_db, target_house_id=42, min_points=3)
+
+    assert result is not None
+    assert len(result) == 3
+    assert result[0]["month"] == "2025-11"
+    assert result[0]["ppm2"] == 148_000
+
+
+def test_price_trend_dedup_disabled_returns_same_points() -> None:
+    """Флаг OFF не ломает возврат данных (backward-compat)."""
+    rows = [
+        {"month": "2025-11", "ppm2": 148_000},
+        {"month": "2025-12", "ppm2": 152_000},
+        {"month": "2026-01", "ppm2": 155_000},
+    ]
+    mock_db = _make_mock_db([], rows)
+
+    with patch("app.services.estimator.settings") as mock_settings:
+        mock_settings.estimate_price_trend_dedup_enabled = False
+        mock_settings.estimate_price_trend_max_age_months = 6
+
+        result = _fetch_price_trend(mock_db, target_house_id=42, min_points=3)
+
+    assert result is not None
+    assert len(result) == 3
+
+
+def test_price_trend_source1_preferred_over_dedup_path() -> None:
+    """Если Source1 (houses_price_dynamics) вернул ≥ min_points → Source2 не вызывается."""
+    source1_rows = [
+        {"month": "2025-11", "ppm2": 140_000},
+        {"month": "2025-12", "ppm2": 145_000},
+        {"month": "2026-01", "ppm2": 150_000},
+    ]
+    mock_db = _make_mock_db(source1_rows, [])
+
+    with patch("app.services.estimator.settings") as mock_settings:
+        mock_settings.estimate_price_trend_dedup_enabled = True
+        mock_settings.estimate_price_trend_max_age_months = 6
+
+        result = _fetch_price_trend(mock_db, target_house_id=42, min_points=3)
+
+    # Source1 вернул 3 точки — Source2 не должен вызываться
+    assert result is not None
+    assert len(result) == 3
+    calls = mock_db.execute.call_args_list
+    # Ровно один вызов (Source1)
+    assert len(calls) == 1
+
+
+if __name__ == "__main__":  # pragma: no cover
+    raise SystemExit(pytest.main([__file__, "-q"]))