diff --git a/backend/app/services/site_finder/ird_overlay_lookup.py b/backend/app/services/site_finder/ird_overlay_lookup.py
index 33cc9b76..3d7681e8 100644
--- a/backend/app/services/site_finder/ird_overlay_lookup.py
+++ b/backend/app/services/site_finder/ird_overlay_lookup.py
@@ -19,7 +19,7 @@ import logging
 from typing import Any
 
 from sqlalchemy import text
-from sqlalchemy.exc import OperationalError, ProgrammingError
+from sqlalchemy.exc import DataError, OperationalError, ProgrammingError
 from sqlalchemy.orm import Session
 
 logger = logging.getLogger(__name__)
@@ -59,8 +59,12 @@ def parcel_ird_overlaps(db: Session, parcel_wkt: str | None) -> dict[str, Any]:
         return {"ird_overlaps": [], "ird_by_kind": {}}
     try:
         rows = db.execute(_IRD_OVERLAP_SQL, {"parcel_wkt": parcel_wkt}).mappings().all()
-    except (OperationalError, ProgrammingError) as exc:
-        # Таблица ещё не задеплоена / БД-ошибка — graceful degrade.
+    except (OperationalError, ProgrammingError, DataError) as exc:
+        # OperationalError — БД недоступна / connection drop.
+        # ProgrammingError — ird_overlays ещё не задеплоена (UndefinedTable, pre-migration).
+        # DataError — malformed WKT в ST_GeomFromText (PostGIS ERROR пробрасывает SQLAlchemy
+        # как DataError/InternalError). parcel_wkt системно-генерируемый, но при D9b-wiring
+        # в analyze graceful-degrade — единственная корректная стратегия (analyze не падает).
         logger.warning("parcel_ird_overlaps: ird_overlays недоступна, skip: %s", exc)
         return {"ird_overlaps": [], "ird_by_kind": {}}
 
diff --git a/backend/app/services/site_finder/quarter_dump_lookup.py b/backend/app/services/site_finder/quarter_dump_lookup.py
index 6dabac98..f066d9c7 100644
--- a/backend/app/services/site_finder/quarter_dump_lookup.py
+++ b/backend/app/services/site_finder/quarter_dump_lookup.py
@@ -20,7 +20,7 @@ from datetime import UTC, datetime, timedelta
 from typing import Any
 
 from sqlalchemy import text
-from sqlalchemy.exc import OperationalError, ProgrammingError
+from sqlalchemy.exc import DataError, OperationalError, ProgrammingError
 from sqlalchemy.orm import Session
 
 logger = logging.getLogger(__name__)
@@ -1066,7 +1066,8 @@ def _get_engineering_structures_by_boundary(
             ),
             {"q": quarter, "wkt": parcel_wkt, "radius_m": radius_m},
         ).fetchall()
-    except (OperationalError, ProgrammingError) as e:
+    except (OperationalError, ProgrammingError, DataError) as e:
+        # DataError — malformed WKT в ST_GeomFromText / ST_GeomFromGeoJSON (PostGIS ERROR).
         logger.warning(
             "engineering_structures query failed for quarter=%s: %s",
             quarter,
@@ -1139,7 +1140,8 @@ def _get_zouit_engineering_overlaps(
             ),
             {"q": quarter, "wkt": parcel_wkt},
         ).fetchall()
-    except (OperationalError, ProgrammingError) as e:
+    except (OperationalError, ProgrammingError, DataError) as e:
+        # DataError — malformed WKT в ST_GeomFromText / ST_GeomFromGeoJSON (PostGIS ERROR).
         logger.warning(
             "zouit_engineering query failed for quarter=%s: %s",
             quarter,
diff --git a/backend/tests/services/test_ird_overlay_lookup.py b/backend/tests/services/test_ird_overlay_lookup.py
index e5a0a945..3e9898c6 100644
--- a/backend/tests/services/test_ird_overlay_lookup.py
+++ b/backend/tests/services/test_ird_overlay_lookup.py
@@ -4,7 +4,8 @@ from __future__ import annotations
 
 from typing import Any
 
-from sqlalchemy.exc import OperationalError
+import pytest
+from sqlalchemy.exc import DataError, OperationalError, ProgrammingError
 
 from app.services.site_finder.ird_overlay_lookup import parcel_ird_overlaps
 
@@ -102,8 +103,32 @@ def test_empty_when_no_overlap() -> None:
     assert res == {"ird_overlaps": [], "ird_by_kind": {}}
 
 
-def test_graceful_when_table_missing() -> None:
-    """ird_overlays ещё не задеплоена → пусто, без падения analyze."""
-    db = _FakeDB(raise_exc=OperationalError("stmt", {}, Exception("no such table")))
+@pytest.mark.parametrize(
+    ("exc", "case"),
+    [
+        (
+            OperationalError("stmt", {}, Exception("no such table")),
+            "operational-error: connection drop / БД недоступна",
+        ),
+        (
+            ProgrammingError("stmt", {}, Exception("relation \"ird_overlays\" does not exist")),
+            "programming-error: UndefinedTable — pre-migration / D9b не задеплоен",
+        ),
+        (
+            DataError("stmt", {}, Exception("parse error - invalid geometry")),
+            "data-error: malformed WKT → PostGIS ST_GeomFromText ERROR",
+        ),
+    ],
+)
+def test_graceful_when_db_fails(exc: Exception, case: str) -> None:
+    """ird_overlays недоступна / malformed WKT → пусто, analyze не падает.
+
+    Покрывает:
+    - OperationalError — БД недоступна.
+    - ProgrammingError — таблица ещё не задеплоена (реальный класс при UndefinedTable).
+    - DataError — malformed parcel_wkt (PostGIS ST_GeomFromText бросает ERROR,
+      SQLAlchemy конвертит в DataError).
+    """
+    db = _FakeDB(raise_exc=exc)
     res = parcel_ird_overlaps(db, _WKT)
-    assert res == {"ird_overlaps": [], "ird_by_kind": {}}
+    assert res == {"ird_overlaps": [], "ird_by_kind": {}}, case