feat(tradein): insufficient_data flag on AggregatedEstimate (#697)

When no comps/anchor are found the estimate returns median=0/range 0-0, and
the frontend can render a literal «0 ₽». Add a computed boolean
insufficient_data (= median_price_rub <= 0) so the UI shows an explicit
«недостаточно данных» state instead.

Implemented as a Pydantic @computed_field derived from median_price_rub —
correct automatically across all four AggregatedEstimate construction sites
(main estimate, _empty_estimate, and both GET-rehydration paths), no DB column,
no risk of per-site drift. Additive/serialized; existing fields untouched.

Refs #697

tradein-mvp/backend/app/schemas/trade_in.py

@@ -9,7 +9,7 @@ from datetime import date, datetime
 from typing import Any, Literal
 from uuid import UUID
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, computed_field
 
 
 class TradeInEstimateInput(BaseModel):
@@ -132,6 +132,18 @@ class AggregatedEstimate(BaseModel):
     confidence: Literal["low", "medium", "high"]
     confidence_explanation: str | None = None  # «Найдено 15 аналогов, разброс ±7%»
     n_analogs: int
+
+    @computed_field  # type: ignore[prop-decorator]
+    @property
+    def insufficient_data(self) -> bool:
+        """#697: нет пригодной оценки — комплов/якоря не нашлось → headline median=0.
+
+        Фронт по этому флагу рендерит явное «недостаточно данных», а не буквальный
+        «0 ₽». Производное от median_price_rub (==0 ⇔ нет оценки), поэтому корректно
+        во всех конструкторах AggregatedEstimate автоматически (вкл. rehydrate на GET).
+        """
+        return self.median_price_rub <= 0
+
     period_months: int  # 24
     analogs: list[AnalogLot]  # top 5-10 listings
     actual_deals: list[AnalogLot]  # реальные продажи last 12 mo

tradein-mvp/backend/tests/test_insufficient_data_flag.py

@@ -0,0 +1,49 @@
+"""#697 — AggregatedEstimate.insufficient_data computed flag.
+
+median=0 (нет комплов/якоря) → insufficient_data=True, чтобы фронт показал
+«недостаточно данных», а не «0 ₽». Производное от median_price_rub.
+"""
+
+import os
+from datetime import UTC, datetime
+from uuid import uuid4
+
+os.environ.setdefault("DATABASE_URL", "postgresql+psycopg://test:test@localhost/test_db")
+
+from app.schemas.trade_in import AggregatedEstimate
+
+
+def _estimate(median: int) -> AggregatedEstimate:
+    return AggregatedEstimate(
+        estimate_id=uuid4(),
+        median_price_rub=median,
+        range_low_rub=0 if median == 0 else median - 100,
+        range_high_rub=0 if median == 0 else median + 100,
+        median_price_per_m2=0 if median == 0 else 150_000,
+        confidence="low" if median == 0 else "medium",
+        n_analogs=0 if median == 0 else 12,
+        period_months=12,
+        analogs=[],
+        actual_deals=[],
+        expires_at=datetime(2026, 6, 1, tzinfo=UTC),
+    )
+
+
+def test_insufficient_when_median_zero() -> None:
+    assert _estimate(0).insufficient_data is True
+
+
+def test_sufficient_when_median_positive() -> None:
+    assert _estimate(6_900_000).insufficient_data is False
+
+
+def test_flag_serialized_in_model_dump() -> None:
+    dump = _estimate(0).model_dump()
+    assert dump["insufficient_data"] is True
+    dump2 = _estimate(5_000_000).model_dump()
+    assert dump2["insufficient_data"] is False
+
+
+def test_negative_median_is_insufficient() -> None:
+    # защита от случайного отрицательного headline.
+    assert _estimate(-1).insufficient_data is True