diff --git a/api/src/api/endpoints/consolidations/osv.py b/api/src/api/endpoints/consolidations/osv.py
index 22a9034..2d89505 100644
--- a/api/src/api/endpoints/consolidations/osv.py
+++ b/api/src/api/endpoints/consolidations/osv.py
@@ -33,7 +33,8 @@ async def list_osv(
     query: Annotated[OsvQuery, Query()],
 ) -> Page[ConsolidatedRowOut]:
     """Строки свода в порядке: имя ЮЛ, счёт, номер строки, первый `entry_id`. Фильтры `legal_entity_id`,
-    `account_root`, `counterparty_type`, `unmapped`, `match_kind` (повторяемый), `q`; `limit` ≤ 2000 (по умолчанию 500).
+    `account_root`, `counterparty_type`, `unmapped`, `counterparty_id`, `match_kind` (повторяемый), `q`;
+    `limit` ≤ 2000 (по умолчанию 500).
     Суммы — строки с двумя знаками."""
     return await service.page(version_id, query, query)
 
diff --git a/api/src/schemas/consolidations.py b/api/src/schemas/consolidations.py
index 0215801..ca4b727 100644
--- a/api/src/schemas/consolidations.py
+++ b/api/src/schemas/consolidations.py
@@ -241,6 +241,18 @@ class GapOut(BaseModel):
     missing_quarters: list[PeriodQuarter]
 
 
+class CounterPairOut(BaseModel):
+    """Пара «держатель видит, встречной записи нет» (§3 п. 9, AURORA-1746) в сводке свода."""
+
+    holder_id: uuid.UUID
+    holder_name: str
+    missing_id: uuid.UUID
+    missing_name: str
+    holder_rows: int
+    missing_unmapped_rows: int
+    missing_rows_total: int
+
+
 class OsvSummaryOut(BaseModel):
     """Сводка по своду версии (`GET …/osv/summary`)."""
 
@@ -249,6 +261,7 @@ class OsvSummaryOut(BaseModel):
     auto_matched_total: int
     documents_total: int
     gaps: list[GapOut]
+    counter_pairs: list[CounterPairOut]
 
 
 class OsvFilters(BaseModel):
@@ -258,6 +271,7 @@ class OsvFilters(BaseModel):
     account_root: str | None = None
     counterparty_type: CounterpartyType | None = None
     unmapped: bool | None = None
+    counterparty_id: uuid.UUID | None = None
     match_kind: list[CounterpartyMatchKind] | None = None
     q: str | None = Field(default=None, max_length=MAX_OSV_QUERY)
 
diff --git a/api/src/services/consolidated_osv.py b/api/src/services/consolidated_osv.py
index 3dd9166..b548d42 100644
--- a/api/src/services/consolidated_osv.py
+++ b/api/src/services/consolidated_osv.py
@@ -36,6 +36,7 @@ from src.schemas.common import Page
 from src.schemas.consolidations import (
     CandidateOut,
     ConsolidatedRowOut,
+    CounterPairOut,
     GapOut,
     OsvFilters,
     OsvPageParams,
@@ -65,6 +66,7 @@ def domain_filter(f: OsvFilters) -> domain.OsvFilter:
         account_root=f.account_root,
         counterparty_type=f.counterparty_type,
         unmapped=f.unmapped,
+        counterparty_id=f.counterparty_id,
         match_kinds=frozenset(f.match_kind or ()),
         q=f.q,
     )
@@ -232,6 +234,10 @@ class ConsolidatedOsvService:
             auto_matched_total=auto_matched_total,
             documents_total=result.consolidated.documents_total,
             gaps=[GapOut.model_validate(gap, from_attributes=True) for gap in result.consolidated.gaps],
+            counter_pairs=[
+                CounterPairOut.model_validate(pair, from_attributes=True)
+                for pair in domain.counter_pairs(result.consolidated.rows, result.members)
+            ],
         )
 
     async def row_for_entry(self, version_id: uuid.UUID, entry_id: uuid.UUID) -> ConsolidatedRowOut | None:
diff --git a/api/tests/test_api_consolidated_osv.py b/api/tests/test_api_consolidated_osv.py
index 5300f21..eff6eeb 100644
--- a/api/tests/test_api_consolidated_osv.py
+++ b/api/tests/test_api_consolidated_osv.py
@@ -277,7 +277,7 @@ async def test_summary_counts_and_page_total_agree(auth_client: AuthClientFactor
 
     assert summary == {
         "rows_total": ROWS_TOTAL, "unmapped_total": UNMAPPED_TOTAL, "auto_matched_total": AUTO_MATCHED_TOTAL,
-        "documents_total": DOCUMENTS_TOTAL, "gaps": [],
+        "documents_total": DOCUMENTS_TOTAL, "gaps": [], "counter_pairs": [],
     }  # fmt: skip
     unmapped = await _page(client, world, "unmapped=true")
     assert unmapped["total"] == summary["unmapped_total"]
@@ -287,6 +287,22 @@ async def test_summary_counts_and_page_total_agree(auth_client: AuthClientFactor
     assert mapped["total"] == ROWS_TOTAL - UNMAPPED_TOTAL
 
 
+@pytest.mark.integration
+async def test_filter_by_counterparty_id(auth_client: AuthClientFactory, seeded: AsyncSession) -> None:
+    world = await _world(seeded)
+    client = await auth_client(KA_RF)
+
+    body = await _page(client, world, f"legal_entity_id={world.a.id}&counterparty_id={world.b.id}")
+
+    # у «ООО А» контрагент Б — в ОСВ 60 (склейка кварталов) и в ОСВ 62
+    assert body["total"] == 2  # noqa: PLR2004
+    assert {(r["legal_entity_name"], r["account_code"], r["counterparty_name"]) for r in body["items"]} == {
+        ("ООО А", "60", "ООО Б"),
+        ("ООО А", "62", "ООО Б"),
+    }
+    assert (await client.get(f"{_url(world)}?counterparty_id=not-a-uuid")).status_code == 422  # noqa: PLR2004
+
+
 @pytest.mark.integration
 async def test_filter_by_match_kind_repeated_param(auth_client: AuthClientFactory, seeded: AsyncSession) -> None:
     world = await _world(seeded)
diff --git a/api/tests/test_api_counterparty_mapping.py b/api/tests/test_api_counterparty_mapping.py
index 31ad5f9..a46ba15 100644
--- a/api/tests/test_api_counterparty_mapping.py
+++ b/api/tests/test_api_counterparty_mapping.py
@@ -902,3 +902,32 @@ async def test_alias_delete_racing_with_move_alias_is_404_without_phantom_event(
         ]
         assert len(removals) == 1  # только удаление при переносе
         assert await session.get(LegalEntityAlias, alias_id) is None
+
+
+@pytest.mark.integration
+async def test_counter_pairs_before_and_after_mapping(auth_client: AuthClientFactory, seeded: AsyncSession) -> None:
+    """Пара «Счастливочная видит РБ, РБ её — нет»: у РБ без ИНН 60/62/66, 76 с ИНН вне справочника (AURORA-1866)."""
+    world = await _world(seeded)
+    client = await auth_client(KA_RF)
+    base = f"/consolidations/versions/{world.version.id}/osv"
+
+    summary = await _summary(client, world)
+
+    assert summary["counter_pairs"] == [
+        {
+            "holder_id": str(world.schastl.id), "holder_name": "ООО «Пекарня Счастливочная»",
+            "missing_id": str(world.rb.id), "missing_name": "АО Русский бисквит",
+            "holder_rows": 1, "missing_unmapped_rows": 3, "missing_rows_total": 5,
+        }
+    ]  # fmt: skip
+    unmapped = await client.get(f"{base}?legal_entity_id={world.rb.id}&unmapped=true")
+    assert unmapped.json()["total"] == 3  # noqa: PLR2004
+    held = await client.get(f"{base}?legal_entity_id={world.schastl.id}&counterparty_id={world.rb.id}")
+    assert held.json()["total"] == 1
+
+    mapped = await client.post(
+        _map_url(world, world.entries[("60", 1)]), json={"legal_entity_id": str(world.schastl.id)}
+    )
+
+    assert mapped.status_code == HTTP_OK, mapped.text
+    assert (await _summary(client, world))["counter_pairs"] == []