diff --git a/tradein-mvp/backend/app/api/v1/trade_in.py b/tradein-mvp/backend/app/api/v1/trade_in.py
index d49fec6a..cb358668 100644
--- a/tradein-mvp/backend/app/api/v1/trade_in.py
+++ b/tradein-mvp/backend/app/api/v1/trade_in.py
@@ -1581,6 +1581,7 @@ def get_sales_vs_listings(
             deals_with_listings=0,
             linkage_rate_pct=0.0,
             median_discount_pct=None,
+            data_quality="no_data",  # #721 ADR v3: нет сделок / улица не извлеклась
             pairs=[],
         )
 
@@ -1686,5 +1687,7 @@ def get_sales_vs_listings(
         deals_with_listings=deals_with_listings,
         linkage_rate_pct=linkage_rate_pct,
         median_discount_pct=median_discount,
+        # #721 ADR v3: total_deals>0 здесь (guard `if not rows` выше → _empty).
+        data_quality="house_linked" if deals_with_listings > 0 else "street_only",
         pairs=pairs,
     )
diff --git a/tradein-mvp/backend/app/schemas/trade_in.py b/tradein-mvp/backend/app/schemas/trade_in.py
index c897c1f7..3cc7d214 100644
--- a/tradein-mvp/backend/app/schemas/trade_in.py
+++ b/tradein-mvp/backend/app/schemas/trade_in.py
@@ -457,6 +457,7 @@ class SalesVsListingsResponse(BaseModel):
     deals_with_listings: int  # сколько имеют связанный listing
     linkage_rate_pct: float  # deals_with_listings / total_deals * 100
     median_discount_pct: float | None  # медиана по парам с listing
+    data_quality: str  # "house_linked" | "street_only" | "no_data" (#721, ADR v3)
     pairs: list[SalesListingPair]  # все пары, sorted by deal_date DESC