diff --git a/api/src/core/exception_handlers.py b/api/src/core/exception_handlers.py
index 9047683..5518839 100644
--- a/api/src/core/exception_handlers.py
+++ b/api/src/core/exception_handlers.py
@@ -18,7 +18,7 @@ from src.core.CONSTANTS import (
     PG_403_ERRORS,
 )
 
-def _error_payload(code: str | int, message: str, field: str | None = None) -> dict:
+def _error_payload(code: int, message: str, field: str = "") -> dict:
     """Формирует структурированный payload ошибки по спеке."""
     return {
         "code": code,
@@ -27,13 +27,12 @@ def _error_payload(code: str | int, message: str, field: str | None = None) -> d
     }
 
 
-def _parse_prefixed_validation_error(message: str) -> tuple[str, str | None]:
+def _parse_prefixed_validation_error(message: str) -> str:
     for prefix in VALIDATION_PREFIXES:
         if message.lower().startswith(prefix):
-            code = prefix[:-1]
-            field = message.split(":", 1)[1].strip() if ":" in message else None
-            return code, field or None
-    return "validation_error", None
+            field = message.split(":", 1)[1].strip() if ":" in message else ""
+            return field or ""
+    return ""
 
 
 def _first_db_message_line(message: str) -> str:
@@ -45,34 +44,42 @@ def _first_db_message_line(message: str) -> str:
     return message.strip()
 
 
-def map_sqlalchemy_error(exc: SQLAlchemyError) -> tuple[int, str, str, str | None]:
+def map_sqlalchemy_error(exc: SQLAlchemyError) -> tuple[int, int, str, str]:
     """Маппинг ошибок SQLAlchemy в HTTP-статус + code/message/field."""
     raw = str(getattr(exc, "orig", exc) or exc).strip()
     message = _first_db_message_line(raw) or "Database error"
     low = message.lower()
 
     if any(low.startswith(prefix) for prefix in VALIDATION_PREFIXES):
-        code, field = _parse_prefixed_validation_error(message)
-        return status.HTTP_422_UNPROCESSABLE_ENTITY, code, message, field
+        status_code = status.HTTP_422_UNPROCESSABLE_ENTITY
+        field = _parse_prefixed_validation_error(message)
+        return status_code, status_code, message, field
     if any(error in low for error in PG_404_ERRORS):
-        return status.HTTP_404_NOT_FOUND, "not_found", message, None
+        status_code = status.HTTP_404_NOT_FOUND
+        return status_code, status_code, message, ""
     if any(error in low for error in PG_403_ERRORS):
-        return status.HTTP_403_FORBIDDEN, "access_denied", message, None
+        status_code = status.HTTP_403_FORBIDDEN
+        return status_code, status_code, message, ""
 
     if isinstance(exc, IntegrityError):
         if any(error in low for error in PG_409_ERRORS):
-            return status.HTTP_409_CONFLICT, "conflict", message, None
+            status_code = status.HTTP_409_CONFLICT
+            return status_code, status_code, message, ""
         if any(error in low for error in PG_400_ERRORS):
-            return status.HTTP_400_BAD_REQUEST, "db_error", message, None
-        return status.HTTP_400_BAD_REQUEST, "db_error", message, None
+            status_code = status.HTTP_400_BAD_REQUEST
+            return status_code, status_code, message, ""
+        status_code = status.HTTP_400_BAD_REQUEST
+        return status_code, status_code, message, ""
 
     if isinstance(exc, OperationalError):
-        return status.HTTP_503_SERVICE_UNAVAILABLE, "db_unavailable", "Database unavailable", None
+        status_code = status.HTTP_503_SERVICE_UNAVAILABLE
+        return status_code, status_code, "Database unavailable", ""
 
-    return status.HTTP_400_BAD_REQUEST, "db_error", message, None
+    status_code = status.HTTP_400_BAD_REQUEST
+    return status_code, status_code, message, ""
 
 
-def map_http_exception(exc: HTTPException) -> tuple[int, str | int, str, str | None]:
+def map_http_exception(exc: HTTPException) -> tuple[int, int, str, str]:
     """Маппинг HTTPException в единый формат ошибки API."""
     status_code = int(exc.status_code)
     detail = exc.detail
@@ -80,13 +87,11 @@ def map_http_exception(exc: HTTPException) -> tuple[int, str | int, str, str | N
     if isinstance(detail, dict):
         message = str(detail.get("message") or detail.get("detail") or "HTTP error")
         field = detail.get("field")
-        if field is not None:
-            field = str(field)
-        code = detail.get("code", status_code)
-        return status_code, code, message, field
+        field_str = str(field) if field is not None else ""
+        return status_code, status_code, message, field_str
 
     message = str(detail) if detail else "HTTP error"
-    return status_code, status_code, message, None
+    return status_code, status_code, message, ""
 
 
 def register_exception_handlers(app: FastAPI) -> None:
@@ -101,38 +106,43 @@ def register_exception_handlers(app: FastAPI) -> None:
 
     @app.exception_handler(AccessDeniedException)
     async def access_denied_exception_handler(request, exc: AccessDeniedException):
+        status_code = status.HTTP_403_FORBIDDEN
         return JSONResponse(
-            status_code=status.HTTP_403_FORBIDDEN,
-            content=_error_payload("access_denied", exc.description),
+            status_code=status_code,
+            content=_error_payload(status_code, exc.description),
         )
 
     @app.exception_handler(ValidationException)
     async def validation_exception_handler(request, exc: ValidationException):
+        status_code = status.HTTP_400_BAD_REQUEST
         return JSONResponse(
-            status_code=status.HTTP_400_BAD_REQUEST,
-            content=_error_payload("validation_error", exc.description, field=exc.field),
+            status_code=status_code,
+            content=_error_payload(status_code, exc.description, field=exc.field or ""),
         )
 
     @app.exception_handler(UserNotFoundException)
     async def user_not_found_exception_handler(request, exc: UserNotFoundException):
+        status_code = status.HTTP_404_NOT_FOUND
         return JSONResponse(
-            status_code=status.HTTP_404_NOT_FOUND,
-            content=_error_payload("user_not_found", exc.description),
+            status_code=status_code,
+            content=_error_payload(status_code, exc.description),
         )
 
     @app.exception_handler(UsernameConflictException)
     async def username_conflict_exception_handler(request, exc: UsernameConflictException):
+        status_code = status.HTTP_409_CONFLICT
         return JSONResponse(
-            status_code=status.HTTP_409_CONFLICT,
-            content=_error_payload("username_conflict", exc.description),
+            status_code=status_code,
+            content=_error_payload(status_code, exc.description),
         )
 
     @app.exception_handler(BasicAppException)
     async def basic_app_exception_handler(request, exc: BasicAppException):
         message = exc.description or "Application error"
+        status_code = status.HTTP_400_BAD_REQUEST
         return JSONResponse(
-            status_code=status.HTTP_400_BAD_REQUEST,
-            content=_error_payload("application_error", message),
+            status_code=status_code,
+            content=_error_payload(status_code, message),
         )
 
     @app.exception_handler(SQLAlchemyError)
diff --git a/api/tests/unit/test_exception_handlers.py b/api/tests/unit/test_exception_handlers.py
index 3887a49..679a2c2 100644
--- a/api/tests/unit/test_exception_handlers.py
+++ b/api/tests/unit/test_exception_handlers.py
@@ -18,9 +18,9 @@ def test_map_sqlalchemy_error_unique_conflict():
     status_code, code, message, field = map_sqlalchemy_error(exc)
 
     assert status_code == status.HTTP_409_CONFLICT
-    assert code == "conflict"
+    assert code == status.HTTP_409_CONFLICT
     assert "duplicate key value" in message
-    assert field is None
+    assert field == ""
 
 
 def test_map_sqlalchemy_error_check_constraint_is_400():
@@ -33,9 +33,9 @@ def test_map_sqlalchemy_error_check_constraint_is_400():
     status_code, code, message, field = map_sqlalchemy_error(exc)
 
     assert status_code == status.HTTP_400_BAD_REQUEST
-    assert code == "db_error"
+    assert code == status.HTTP_400_BAD_REQUEST
     assert "violates check constraint" in message
-    assert field is None
+    assert field == ""
 
 
 def test_map_sqlalchemy_error_validation_prefix():
@@ -45,7 +45,7 @@ def test_map_sqlalchemy_error_validation_prefix():
     status_code, code, message, field = map_sqlalchemy_error(exc)
 
     assert status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
-    assert code == "unknown_column"
+    assert code == status.HTTP_422_UNPROCESSABLE_ENTITY
     assert message == "unknown_column: q5.plan"
     assert field == "q5.plan"
 
@@ -57,9 +57,9 @@ def test_map_sqlalchemy_error_not_found():
     status_code, code, message, field = map_sqlalchemy_error(exc)
 
     assert status_code == status.HTTP_404_NOT_FOUND
-    assert code == "not_found"
+    assert code == status.HTTP_404_NOT_FOUND
     assert "не существует" in message
-    assert field is None
+    assert field == ""
 
 
 def test_map_sqlalchemy_error_role_window_prefixes():
@@ -67,17 +67,17 @@ def test_map_sqlalchemy_error_role_window_prefixes():
     role_exc.orig = Exception("role_not_allowed: q1.m1")
     status_code, code, message, field = map_sqlalchemy_error(role_exc)
     assert status_code == status.HTTP_403_FORBIDDEN
-    assert code == "access_denied"
+    assert code == status.HTTP_403_FORBIDDEN
     assert message == "role_not_allowed: q1.m1"
-    assert field is None
+    assert field == ""
 
     window_exc = SQLAlchemyError()
     window_exc.orig = Exception("window_closed: q1.m1 (closed 2026-05-01T00:00:00Z)")
     status_code, code, message, field = map_sqlalchemy_error(window_exc)
     assert status_code == status.HTTP_403_FORBIDDEN
-    assert code == "access_denied"
+    assert code == status.HTTP_403_FORBIDDEN
     assert message.startswith("window_closed:")
-    assert field is None
+    assert field == ""
 
 
 def test_map_sqlalchemy_error_operational():
@@ -90,16 +90,20 @@ def test_map_sqlalchemy_error_operational():
     status_code, code, message, field = map_sqlalchemy_error(exc)
 
     assert status_code == status.HTTP_503_SERVICE_UNAVAILABLE
-    assert code == "db_unavailable"
+    assert code == status.HTTP_503_SERVICE_UNAVAILABLE
     assert message == "Database unavailable"
-    assert field is None
+    assert field == ""
 
 
 def test_error_payload_matches_spec_shape():
-    payload = _error_payload("unknown_column", "unknown_column: q5.plan", "q5.plan")
+    payload = _error_payload(
+        status.HTTP_422_UNPROCESSABLE_ENTITY,
+        "unknown_column: q5.plan",
+        "q5.plan",
+    )
 
     assert payload == {
-        "code": "unknown_column",
+        "code": status.HTTP_422_UNPROCESSABLE_ENTITY,
         "field": "q5.plan",
         "message": "unknown_column: q5.plan",
     }
@@ -116,7 +120,7 @@ def test_map_http_exception_validation_prefix():
     assert status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
     assert code == status.HTTP_422_UNPROCESSABLE_ENTITY
     assert message == "unknown_column: q5.plan"
-    assert field is None
+    assert field == ""
 
 
 def test_map_http_exception_from_structured_detail():
@@ -128,7 +132,7 @@ def test_map_http_exception_from_structured_detail():
     status_code, code, message, field = map_http_exception(exc)
 
     assert status_code == status.HTTP_400_BAD_REQUEST
-    assert code == "validation_error"
+    assert code == status.HTTP_400_BAD_REQUEST
     assert message == "bad input"
     assert field == "username"
 
@@ -141,7 +145,7 @@ def test_map_http_exception_unauthorized():
     assert status_code == status.HTTP_401_UNAUTHORIZED
     assert code == status.HTTP_401_UNAUTHORIZED
     assert message == "Недействительный токен"
-    assert field is None
+    assert field == ""
 
 
 def test_map_http_exception_not_found_maps_code_from_status():
@@ -152,4 +156,4 @@ def test_map_http_exception_not_found_maps_code_from_status():
     assert status_code == status.HTTP_404_NOT_FOUND
     assert code == status.HTTP_404_NOT_FOUND
     assert message == "not found"
-    assert field is None
+    assert field == ""
diff --git a/api/tests/unit/test_exception_handlers_http_shape.py b/api/tests/unit/test_exception_handlers_http_shape.py
index cde3af6..b6cb485 100644
--- a/api/tests/unit/test_exception_handlers_http_shape.py
+++ b/api/tests/unit/test_exception_handlers_http_shape.py
@@ -39,7 +39,7 @@ def test_http_exception_returns_structured_payload():
     assert response.status_code == status.HTTP_401_UNAUTHORIZED
     assert response.json() == {
         "code": status.HTTP_401_UNAUTHORIZED,
-        "field": None,
+        "field": "",
         "message": "Недействительный токен",
     }
 
@@ -51,7 +51,7 @@ def test_http_validation_exception_extracts_field():
     assert response.status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
     assert response.json() == {
         "code": status.HTTP_422_UNPROCESSABLE_ENTITY,
-        "field": None,
+        "field": "",
         "message": "unknown_column: q5.plan",
     }
 
@@ -62,7 +62,7 @@ def test_sqlalchemy_exception_returns_structured_payload():
 
     assert response.status_code == status.HTTP_404_NOT_FOUND
     assert response.json() == {
-        "code": "not_found",
-        "field": None,
+        "code": status.HTTP_404_NOT_FOUND,
+        "field": "",
         "message": "budget_form #99 не существует",
     }