diff --git a/backend/src/cyclone/api.py b/backend/src/cyclone/api.py
index 244cca2..b3a7706 100644
--- a/backend/src/cyclone/api.py
+++ b/backend/src/cyclone/api.py
@@ -499,6 +499,18 @@ def list_claims(
     }
 
 
+@app.get("/api/reconciliation/unmatched")
+def get_reconciliation_unmatched() -> dict:
+    """Return unmatched Claims (left) and unmatched Remittances (right).
+
+    Powers the reconciliation review surface: every Claim with no
+    paired Remittance appears on the left, every Remittance with no
+    paired Claim appears on the right. The two lists are always present
+    (empty list, never absent) so the UI can index unconditionally.
+    """
+    return store.list_unmatched(kind="both")
+
+
 @app.get("/api/remittances")
 def list_remittances(
     request: Request,
diff --git a/backend/tests/test_api_gets.py b/backend/tests/test_api_gets.py
index 5f53df9..db1c17e 100644
--- a/backend/tests/test_api_gets.py
+++ b/backend/tests/test_api_gets.py
@@ -287,3 +287,113 @@ def test_claims_default_accept_returns_json(seeded_store):
     assert "total" in body
     assert "returned" in body
     assert "has_more" in body
+
+
+# --------------------------------------------------------------------------- #
+# /api/reconciliation/unmatched (T14)
+# --------------------------------------------------------------------------- #
+
+
+def test_get_reconciliation_unmatched_empty(client: TestClient):
+    """With no parsed batches, both sides of the unmatched list are empty."""
+    resp = client.get("/api/reconciliation/unmatched")
+    assert resp.status_code == 200
+    assert resp.json() == {"claims": [], "remittances": []}
+
+
+def test_get_reconciliation_unmatched_returns_orphans(client: TestClient):
+    """An unmatched Claim (left) and an unmatched Remittance (right) both surface.
+
+    The 837 subscriber's ``member_id="M1"`` intentionally differs from the
+    835 remit's ``payer_claim_control_number="PCN-OTHER"`` so the auto-matcher
+    in ``reconcile.run`` does not pair them on ingest — we want them to land
+    in the unmatched list so the endpoint has something to return.
+    """
+    from datetime import date, datetime, timezone
+    from decimal import Decimal
+
+    from cyclone.parsers.models import (
+        BatchSummary, BillingProvider, ClaimHeader, ClaimOutput,
+        Envelope, Payer, ParseResult, Subscriber, ValidationReport,
+    )
+    from cyclone.parsers.models_835 import (
+        BatchSummary as BatchSummary835,
+        ClaimPayment, Envelope as Envelope835,
+        FinancialInfo, Payer835, ParseResult835, Payee835,
+        ReassociationTrace,
+    )
+    from cyclone.store import BatchRecord837, BatchRecord835
+
+    # Add a single 837 Claim. member_id="M1" so PCN-based auto-match won't pair it.
+    co = ClaimOutput(
+        claim_id="CLM-1",
+        control_number="0001",
+        transaction_date=date(2026, 6, 19),
+        billing_provider=BillingProvider(name="Test", npi="1234567890"),
+        subscriber=Subscriber(
+            first_name="Jane", last_name="Doe", member_id="M1",
+        ),
+        payer=Payer(name="Test Payer", id="P1"),
+        claim=ClaimHeader(
+            claim_id="CLM-1", total_charge=Decimal("100"),
+            frequency_code="1", place_of_service="11",
+        ),
+        diagnoses=[],
+        service_lines=[],
+        validation=ValidationReport(passed=True, errors=[], warnings=[]),
+        raw_segments=[],
+    )
+    global_store.add(BatchRecord837(
+        id="b-837", kind="837p", input_filename="c.txt",
+        parsed_at=datetime(2026, 6, 19, 12, 0, tzinfo=timezone.utc),
+        result=ParseResult(
+            claims=[co],
+            summary=BatchSummary(
+                input_file="c.txt", control_number="0001",
+                transaction_date=date(2026, 6, 19),
+                total_claims=1, passed=1, failed=0,
+            ),
+        ),
+    ))
+
+    # Add a single 835 Remittance with PCN="PCN-OTHER" (won't auto-match "M1").
+    cp = ClaimPayment(
+        payer_claim_control_number="PCN-OTHER",
+        status_code="1",
+        total_charge=Decimal("50"), total_paid=Decimal("50"),
+        service_payments=[],
+    )
+    global_store.add(BatchRecord835(
+        id="b-835", kind="835", input_filename="e.txt",
+        parsed_at=datetime(2026, 6, 19, 12, 5, tzinfo=timezone.utc),
+        result=ParseResult835(
+            envelope=Envelope835(
+                sender_id="S", receiver_id="R", control_number="0001",
+                transaction_date=date(2026, 6, 19),
+            ),
+            financial_info=FinancialInfo(
+                handling_code="C", paid_amount=Decimal("0"),
+                credit_debit_flag="C", payment_method=None,
+            ),
+            trace=ReassociationTrace(
+                trace_type_code="1", trace_number="0001",
+                originating_company_id="S",
+            ),
+            payer=Payer835(name="X", id="SKCO0"),
+            payee=Payee835(name="Y", npi="1234567890"),
+            claims=[cp],
+            summary=BatchSummary835(
+                input_file="e.txt", control_number="0001",
+                transaction_date=date(2026, 6, 19),
+                total_claims=1, passed=1, failed=0,
+            ),
+        ),
+    ))
+
+    resp = client.get("/api/reconciliation/unmatched")
+    assert resp.status_code == 200
+    body = resp.json()
+    assert len(body["claims"]) == 1
+    assert body["claims"][0]["id"] == "CLM-1"
+    assert len(body["remittances"]) == 1
+    assert body["remittances"][0]["payerClaimControlNumber"] == "PCN-OTHER"