fix: qualify corporate-action ledger reads (#36)

tests/test_v1_portfolios_holdings.py

@@ -7,7 +7,7 @@ Covers AC-1~11 from REQ-043.
 from __future__ import annotations
 
 from contextlib import ExitStack
-from datetime import datetime, timezone
+from datetime import UTC, datetime, timezone
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -286,6 +286,40 @@ class TestAC2PartialSellWacUnchanged:
         assert resp.json()["total_cost_basis"] == pytest.approx(500_000.0)
 
 
+def test_corporate_action_row_keeps_holdings_cost_basis_http_200() -> None:
+    buy = _make_entry(
+        ledger_entry_id=1,
+        side="buy",
+        quantity=20,
+        price=100,
+        executed_at=datetime(2026, 9, 1, tzinfo=UTC),
+    )
+    corporate_action = LedgerEntry(
+        ledger_entry_id=2,
+        portfolio_id=_PORTFOLIO_ID,
+        source="corporate_action",
+        side="stock_consolidation",
+        quantity=10,
+        price=200,
+        recorded_at=datetime(2026, 9, 2, tzinfo=UTC),
+        corporate_action={"action_type": "stock_consolidation"},
+    )
+    repo = _make_service_repo(
+        portfolio=_make_portfolio(asset_quantity=10),
+        trades=[buy, corporate_action],
+    )
+
+    with _with_repo(repo):
+        response = _make_client(_make_settings()).get(
+            _PATH,
+            headers={"Authorization": "Bearer tok"},
+        )
+
+    assert response.status_code == 200
+    assert response.json()["cost_basis_per_unit"] == pytest.approx(100)
+    assert response.json()["total_cost_basis"] == pytest.approx(1000)
+
+
 # ---------------------------------------------------------------------------
 # AC-3: user read_token (owner) → 200 + normal response
 # ---------------------------------------------------------------------------