diff --git a/backend/src/fintracker/api/app.py b/backend/src/fintracker/api/app.py
index 168c72f..c13a864 100644
--- a/backend/src/fintracker/api/app.py
+++ b/backend/src/fintracker/api/app.py
@@ -23,6 +23,7 @@ from fintracker.api.routers import (
     events,
     health,
     instruments,
+    links,
     metrics,
     networth,
     rules,
@@ -86,6 +87,7 @@ def create_app() -> FastAPI:
     app.include_router(analytics.router, prefix=API_PREFIX)
     app.include_router(events.router, prefix=API_PREFIX)
     app.include_router(instruments.router, prefix=API_PREFIX)
+    app.include_router(links.router, prefix=API_PREFIX)
     app.include_router(metrics.router, prefix=API_PREFIX)
     if settings.web_dir is not None:
         mount_web(app, settings.web_dir, API_PREFIX)
diff --git a/backend/src/fintracker/api/routers/links.py b/backend/src/fintracker/api/routers/links.py
new file mode 100644
index 0000000..ae33601
--- /dev/null
+++ b/backend/src/fintracker/api/routers/links.py
@@ -0,0 +1,151 @@
+"""Manual review and confirmation of ZenMoney <-> broker cash-flow links (plan §1.6 C, §4).
+
+`ledger/matching.py` runs automatically after every refresh and links what it can; this
+router is where the leftovers get resolved by hand. `GET /links/unmatched` recomputes the
+candidate pools live rather than reading the last refresh's `FINDINGS` (a snapshot that goes
+stale the moment a new sync runs), and shows only what has no `flow_link` yet, of either kind.
+"""
+
+from __future__ import annotations
+
+from decimal import Decimal
+
+from fastapi import APIRouter, status
+from sqlalchemy import select
+
+from fintracker.api.deps import CurrentUser, SessionDep
+from fintracker.api.errors import Problem
+from fintracker.api.schemas.links import (
+    LinkCreate,
+    LinkOut,
+    UnmatchedBrokerOut,
+    UnmatchedOut,
+    UnmatchedZmOut,
+)
+from fintracker.ledger.matching import (
+    _load_broker_candidates,
+    _load_zm_candidates,
+    business_days_between,
+)
+from fintracker.models import CashTxn, Event, FlowLink, FlowLinkKind, FlowType
+
+router = APIRouter(prefix="/links", tags=["links"])
+
+ZERO = Decimal(0)
+
+
+@router.get("/unmatched", name="unmatched")
+async def unmatched(session: SessionDep, _: CurrentUser) -> UnmatchedOut:
+    """Every candidate that survives matching without a link, on either side."""
+    linked_txns = set((await session.execute(select(FlowLink.cash_txn_id))).scalars().all())
+    linked_events = set((await session.execute(select(FlowLink.event_id))).scalars().all())
+
+    zm = [c for c in await _load_zm_candidates(session) if c.cash_txn_id not in linked_txns]
+    broker = [c for c in await _load_broker_candidates(session) if c.event_id not in linked_events]
+
+    txns: dict[int, CashTxn] = {}
+    if zm:
+        rows = (
+            await session.execute(select(CashTxn).where(CashTxn.id.in_(c.cash_txn_id for c in zm)))
+        ).scalars()
+        txns = {t.id: t for t in rows}
+
+    return UnmatchedOut(
+        zm=[
+            UnmatchedZmOut(
+                cash_txn_id=c.cash_txn_id,
+                date=c.date,
+                amount=c.amount,
+                currency=c.currency,
+                direction=c.direction.value,
+                broker_account_id=c.broker_account_id,
+                route=c.route,
+                payee=txns[c.cash_txn_id].payee if c.cash_txn_id in txns else None,
+                comment=txns[c.cash_txn_id].comment if c.cash_txn_id in txns else None,
+            )
+            for c in zm
+        ],
+        broker=[
+            UnmatchedBrokerOut(
+                event_id=c.event_id,
+                account_id=c.account_id,
+                date=c.date,
+                amount=c.amount,
+                currency=c.currency,
+                direction=c.direction.value,
+            )
+            for c in broker
+        ],
+    )
+
+
+@router.post("", name="create", status_code=status.HTTP_201_CREATED)
+async def create_link(body: LinkCreate, session: SessionDep, _: CurrentUser) -> LinkOut:
+    """Confirm a pairing the matcher missed. Never touched by the automatic rebuild afterwards."""
+    txn = await session.get(CashTxn, body.cash_txn_id)
+    if txn is None:
+        raise Problem(404, "Not Found", f"Нет транзакции ZenMoney #{body.cash_txn_id}")
+    event = await session.get(Event, body.event_id)
+    if event is None:
+        raise Problem(404, "Not Found", f"Нет события #{body.event_id}")
+
+    if (
+        await session.execute(select(FlowLink).where(FlowLink.cash_txn_id == body.cash_txn_id))
+    ).scalar_one_or_none() is not None:
+        raise Problem(409, "Conflict", f"Транзакция #{body.cash_txn_id} уже связана")
+    if (
+        await session.execute(select(FlowLink).where(FlowLink.event_id == body.event_id))
+    ).scalar_one_or_none() is not None:
+        raise Problem(409, "Conflict", f"Событие #{body.event_id} уже связано")
+
+    zm_amount = txn.income if txn.income > ZERO else txn.outcome
+    zm_currency = (txn.income_currency if txn.income > ZERO else txn.outcome_currency) or "RUB"
+    event_amount = abs(event.amount or ZERO)
+    event_currency = (event.currency or "RUB").upper()
+    if zm_currency.upper() != event_currency:
+        raise Problem(
+            400, "Bad Request", f"Валюты не совпадают: {zm_currency.upper()} vs {event_currency}"
+        )
+
+    link = FlowLink(
+        cash_txn_id=body.cash_txn_id,
+        event_id=body.event_id,
+        kind=FlowLinkKind.manual,
+        confidence=Decimal(1),
+        amount_delta=abs(zm_amount - event_amount),
+        currency=zm_currency.upper(),
+        day_gap=business_days_between(txn.date, event.trade_date),
+        note="manual",
+    )
+    session.add(link)
+    # the point of the link: a linked transfer is not spending, same overwrite
+    # `ledger/matching.py` does for the automatic ones
+    txn.flow_type = FlowType.internal_transfer
+    await session.commit()
+    await session.refresh(link)
+    return _link_out(link)
+
+
+@router.delete("/{link_id}", name="delete", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_link(link_id: int, session: SessionDep, _: CurrentUser) -> None:
+    """Undo a link, manual or automatic. `flow_type` reverts on the next `POST /metrics/refresh`,
+    when `classify` rebuilds it from the rules and `matching` no longer overwrites it."""
+    link = await session.get(FlowLink, link_id)
+    if link is None:
+        raise Problem(404, "Not Found", f"Нет связи #{link_id}")
+    await session.delete(link)
+    await session.commit()
+
+
+def _link_out(link: FlowLink) -> LinkOut:
+    return LinkOut(
+        id=link.id,
+        cash_txn_id=link.cash_txn_id,
+        event_id=link.event_id,
+        kind=link.kind.value,
+        confidence=link.confidence,
+        amount_delta=link.amount_delta,
+        currency=link.currency,
+        day_gap=link.day_gap,
+        note=link.note,
+    )
diff --git a/backend/src/fintracker/api/schemas/links.py b/backend/src/fintracker/api/schemas/links.py
new file mode 100644
index 0000000..367ea91
--- /dev/null
+++ b/backend/src/fintracker/api/schemas/links.py
@@ -0,0 +1,55 @@
+"""Schemas for manual review of ZenMoney <-> broker cash-flow links (plan §1.6 C, §4)."""
+
+from __future__ import annotations
+
+from datetime import date
+
+from pydantic import BaseModel
+
+from fintracker.api.schemas.common import Money
+
+
+class UnmatchedZmOut(BaseModel):
+    cash_txn_id: int
+    date: date
+    amount: Money
+    """Always positive: the magnitude that crossed the boundary."""
+    currency: str
+    direction: str
+    """to_broker | from_broker."""
+    broker_account_id: int
+    route: str
+    """account_link | mirror | rule — how the broker account was identified."""
+    payee: str | None
+    comment: str | None
+
+
+class UnmatchedBrokerOut(BaseModel):
+    event_id: int
+    account_id: int
+    date: date
+    amount: Money
+    currency: str
+    direction: str
+
+
+class UnmatchedOut(BaseModel):
+    zm: list[UnmatchedZmOut]
+    broker: list[UnmatchedBrokerOut]
+
+
+class LinkCreate(BaseModel):
+    cash_txn_id: int
+    event_id: int
+
+
+class LinkOut(BaseModel):
+    id: int
+    cash_txn_id: int
+    event_id: int
+    kind: str
+    confidence: Money
+    amount_delta: Money
+    currency: str
+    day_gap: int
+    note: str | None
diff --git a/backend/tests/api/test_links_api.py b/backend/tests/api/test_links_api.py
new file mode 100644
index 0000000..4406cd1
--- /dev/null
+++ b/backend/tests/api/test_links_api.py
@@ -0,0 +1,104 @@
+"""Manual review of ZenMoney <-> broker cash-flow links, over the API."""
+
+from datetime import timedelta
+
+import pytest
+from httpx import AsyncClient
+
+from factories import make_account, make_event, make_txn
+from fintracker.analytics import today_local
+from fintracker.models import AccountKind, AccountRole, EventKind
+
+
+@pytest.fixture
+async def leftover(app) -> dict[str, int]:
+    """A transfer and a deposit too far apart in amount to auto-match: both stay unmatched."""
+    card = await make_account(name="Карта")
+    broker_account = await make_account(
+        name="ИИС", kind=AccountKind.broker, role=AccountRole.investment, source="tinvest"
+    )
+    mirror = await make_account(
+        name="ИИС (зеркало)", include_in_net_worth=False, mirror_of_account_id=broker_account
+    )
+    d = today_local() - timedelta(days=10)
+
+    txn_id = await make_txn(
+        d, income="10000", income_account_id=mirror, outcome="10000", outcome_account_id=card
+    )
+    event_id = await make_event(d, account_id=broker_account, kind=EventKind.deposit, amount="9500")
+    return {"txn": txn_id, "event": event_id, "broker_account": broker_account}
+
+
+async def test_unmatched_lists_both_sides_of_a_leftover(
+    client: AsyncClient, auth_headers: dict[str, str], leftover: dict[str, int]
+):
+    r = await client.get("/api/v1/links/unmatched", headers=auth_headers)
+    assert r.status_code == 200, r.text
+    body = r.json()
+    assert [c["cash_txn_id"] for c in body["zm"]] == [leftover["txn"]]
+    assert [c["event_id"] for c in body["broker"]] == [leftover["event"]]
+
+
+async def test_manual_link_reclassifies_the_transfer_and_leaves_unmatched(
+    client: AsyncClient, auth_headers: dict[str, str], leftover: dict[str, int]
+):
+    r = await client.post(
+        "/api/v1/links",
+        headers=auth_headers,
+        json={"cash_txn_id": leftover["txn"], "event_id": leftover["event"]},
+    )
+    assert r.status_code == 201, r.text
+    link = r.json()
+    assert link["kind"] == "manual"
+    assert link["amount_delta"] == "500.0000000000"
+
+    r = await client.get("/api/v1/links/unmatched", headers=auth_headers)
+    assert r.json() == {"zm": [], "broker": []}
+
+    r = await client.get("/api/v1/transactions", headers=auth_headers)
+    txn = next(t for t in r.json()["items"] if t["id"] == leftover["txn"])
+    assert txn["flow_type"] == "internal_transfer"
+
+
+async def test_a_linked_side_cannot_be_linked_again(
+    client: AsyncClient, auth_headers: dict[str, str], leftover: dict[str, int]
+):
+    body = {"cash_txn_id": leftover["txn"], "event_id": leftover["event"]}
+    r = await client.post("/api/v1/links", headers=auth_headers, json=body)
+    assert r.status_code == 201, r.text
+
+    other_event = await make_event(
+        today_local(), account_id=leftover["broker_account"], kind=EventKind.deposit, amount="1"
+    )
+    r = await client.post(
+        "/api/v1/links",
+        headers=auth_headers,
+        json={"cash_txn_id": leftover["txn"], "event_id": other_event},
+    )
+    assert r.status_code == 409
+
+
+async def test_delete_link_brings_the_pair_back_to_unmatched(
+    client: AsyncClient, auth_headers: dict[str, str], leftover: dict[str, int]
+):
+    body = {"cash_txn_id": leftover["txn"], "event_id": leftover["event"]}
+    r = await client.post("/api/v1/links", headers=auth_headers, json=body)
+    link_id = r.json()["id"]
+
+    r = await client.delete(f"/api/v1/links/{link_id}", headers=auth_headers)
+    assert r.status_code == 204
+
+    r = await client.get("/api/v1/links/unmatched", headers=auth_headers)
+    body = r.json()
+    assert [c["cash_txn_id"] for c in body["zm"]] == [leftover["txn"]]
+    assert [c["event_id"] for c in body["broker"]] == [leftover["event"]]
+
+
+async def test_unknown_ids_are_a_problem(client: AsyncClient, auth_headers: dict[str, str]):
+    r = await client.post(
+        "/api/v1/links", headers=auth_headers, json={"cash_txn_id": 999, "event_id": 999}
+    )
+    assert r.status_code == 404
+
+    r = await client.delete("/api/v1/links/999", headers=auth_headers)
+    assert r.status_code == 404