diff --git a/api/src/repositories/directories.py b/api/src/repositories/directories.py
index 68d25f7..b91aafa 100644
--- a/api/src/repositories/directories.py
+++ b/api/src/repositories/directories.py
@@ -381,11 +381,15 @@ async def lock_alias_key(session: AsyncSession, normalized: str) -> None:
     await session.execute(select(func.pg_advisory_xact_lock(key)))
 
 
-async def get_alias(session: AsyncSession, entity_id: uuid.UUID, alias_id: uuid.UUID) -> LegalEntityAlias | None:
-    """Алиас по id, только если он принадлежит ЮЛ `entity_id`."""
+async def get_alias(
+    session: AsyncSession, entity_id: uuid.UUID, alias_id: uuid.UUID, *, refresh: bool = False
+) -> LegalEntityAlias | None:
+    """Алиас по id, только если он принадлежит ЮЛ `entity_id`; `refresh` — состояние строки заменяется свежим из БД."""
     stmt = select(LegalEntityAlias).where(
         LegalEntityAlias.id == alias_id, LegalEntityAlias.legal_entity_id == entity_id
     )
+    if refresh:
+        stmt = stmt.execution_options(populate_existing=True)
     return (await session.execute(stmt)).scalar_one_or_none()
 
 
diff --git a/api/src/services/aliases.py b/api/src/services/aliases.py
index c4589aa..8456531 100644
--- a/api/src/services/aliases.py
+++ b/api/src/services/aliases.py
@@ -77,6 +77,12 @@ class AliasService:
         """Удаляет алиас этого ЮЛ (иначе 404); `before_value` аудита — удалённые значения."""
         entity = await self._get_entity(entity_id)
         alias = await repo.get_alias(self._session, entity.id, alias_id)
+        if alias is None:
+            raise NotFoundError(ALIAS_NOT_FOUND)
+        # T11.3: та же advisory-блокировка, что у `add` и ручного сопоставления (design №66); без неё удаление
+        # гонялось бы с `move_alias`, и обе стороны писали бы событие об удалении одного алиаса
+        await repo.lock_alias_key(self._session, alias.normalized_alias)
+        alias = await repo.get_alias(self._session, entity.id, alias_id, refresh=True)  # перенос мог удалить его
         if alias is None:
             raise NotFoundError(ALIAS_NOT_FOUND)
         before = alias_payload(alias)
diff --git a/api/tests/test_api_counterparty_mapping.py b/api/tests/test_api_counterparty_mapping.py
index 5c6517b..99cde4f 100644
--- a/api/tests/test_api_counterparty_mapping.py
+++ b/api/tests/test_api_counterparty_mapping.py
@@ -17,6 +17,8 @@ from sqlalchemy import func, select, text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker
 
 from src.api.dependencies.audit import RequestAudit
+from src.common.clock import utc_now
+from src.domain.aliases import normalize_alias
 from src.domain.policy import VisibilityScope
 from src.models.access import AppUser
 from src.models.audit_ex import AuditEvent
@@ -33,6 +35,7 @@ from src.models.enums import (
 )
 from src.models.files import Document
 from src.models.osv import OsvEntry
+from src.repositories import directories as directories_repo
 from src.schemas.consolidations import MapCounterpartyIn
 from src.services.audit import AuditService
 from src.services.counterparty_mapping import CounterpartyMappingService
@@ -65,6 +68,8 @@ NAME = "Пекарня Счастливочная ООО"
 ALIEN_INN = "7700000000"
 MAX_CANDIDATES = 100
 LOCK_WAIT_SECONDS = 10.0
+ADMIN = "admin@armka.local"
+ENTITIES = "/directories/legal-entities"
 
 
 @dataclass
@@ -820,3 +825,73 @@ async def test_concurrent_mappings_in_two_versions_serialize_on_shared_rows(
         events = await _events(session, AuditAction.OSV_COUNTERPARTY_MAP)
         assert [event.consolidation_version_id for event in events] == [q2_id, q3_id]
         assert events[1].before_value == {"counterparty_id": str(chkf_id), "match_kind": "PROPAGATED"}
+
+
+@pytest.mark.integration
+async def test_manual_mapping_waits_for_alias_advisory_lock(
+    committed_sessionmaker: async_sessionmaker[AsyncSession], committed_client: AuthClientFactory
+) -> None:
+    """M-4 (design №66): ручное сопоставление берёт `lock_alias_key` по нормализованному имени строки — пока другая
+    транзакция держит блокировку этого алиаса (справочник, перенос), запрос ждёт, а после её commit завершается."""
+    async with committed_sessionmaker() as setup, setup.begin():
+        world = await _world(setup)
+    entry_id = world.entries[("60", 1)]
+    client = await committed_client(KA_RF)
+
+    async with committed_sessionmaker() as holder, holder.begin():
+        await directories_repo.lock_alias_key(holder, normalize_alias(NAME))
+        racing = asyncio.create_task(
+            client.post(_map_url(world, entry_id), json={"legal_entity_id": str(world.schastl.id)})
+        )
+        await _wait_for_lock_waiter(committed_sessionmaker)
+        assert not racing.done()
+    response = await asyncio.wait_for(racing, LOCK_WAIT_SECONDS)
+
+    assert response.status_code == HTTP_OK, response.text
+    assert response.json()["alias_created"] is True
+
+
+@pytest.mark.integration
+async def test_alias_delete_racing_with_move_alias_is_404_without_phantom_event(
+    committed_sessionmaker: async_sessionmaker[AsyncSession], committed_client: AuthClientFactory
+) -> None:
+    """T11.3: `DELETE …/aliases/{id}` берёт ту же advisory-блокировку, что ручное сопоставление: пока перенос
+    (`move_alias`) не зафиксирован, удаление ждёт, после commit находит алиас уже удалённым — 404, а фантомного
+    события `LEGAL_ENTITY_CHANGE` об удалении (вторая запись про тот же алиас) нет."""
+    async with committed_sessionmaker() as setup, setup.begin():
+        world = await _world(setup)
+        owner = await _user(setup, KA_RF)
+        alias = LegalEntityAlias(
+            legal_entity_id=world.schastl.id,
+            alias=NAME,
+            normalized_alias=normalize_alias(NAME),
+            created_by=owner.id,
+            created_at=utc_now(),
+        )
+        setup.add(alias)
+        await setup.flush()
+        alias_id, owner_id = alias.id, owner.id
+    entry_id = world.entries[("60", 1)]
+    admin = await committed_client(ADMIN)
+
+    async with committed_sessionmaker() as holder, holder.begin():
+        audit = RequestAudit(service=AuditService(holder), user_id=owner_id, ip_address=None, user_agent=None)
+        service = CounterpartyMappingService(holder, audit, VisibilityScope(office_id=None))
+        moved = await service.map(
+            world.version.id, entry_id, MapCounterpartyIn(legal_entity_id=world.rb.id, move_alias=True)
+        )
+        assert moved.alias_moved_from == world.schastl.id
+        racing = asyncio.create_task(admin.delete(f"{ENTITIES}/{world.schastl.id}/aliases/{alias_id}"))
+        await _wait_for_lock_waiter(committed_sessionmaker)
+        assert not racing.done()
+    response = await asyncio.wait_for(racing, LOCK_WAIT_SECONDS)
+
+    assert response.status_code == HTTP_NOT_FOUND, response.text
+    async with committed_sessionmaker() as session:
+        removals = [
+            event
+            for event in await _events(session, AuditAction.LEGAL_ENTITY_CHANGE)
+            if event.object_id == alias_id and event.before_value is not None
+        ]
+        assert len(removals) == 1  # только удаление при переносе
+        assert await session.get(LegalEntityAlias, alias_id) is None