feat(slot): BAT-029 M2(a)/M3 — holding 불일치 reconcile + slots 단일 뷰 (dcy-020/REQ-062·063)

- REQ-062 divergence: list_holding_slots(protocol+in_memory+PG) +
  reconcile_core_holdings(A=코어 holding/broker0→error, C=수량 불일치→warning,
  B=broker 보유/코어 없음→warning; 자동 청산 없음 issue #15). snapshot_scheduler
  자산 중심 모드에서 best-effort 호출, daemon slot_service 배선.
- REQ-063: slot_to_dict 에 universe_detached(retired_at) 추가 — slots 단일 뷰 tombstone 표시.
- 신규 테스트: test_holding_divergence(4).

M2(b) 청산 수량 브로커 정본(execution dispatch)은 라이브 집행 변경 → BAT-δ carry-over.

검증: 단위 393 passed / 36 skipped, PG-gated 18 passed, ruff clean. legacy 무파손.
REQ-061/062/063 Approved 유지(γ 경로 도입 검증; default 전환·M2(b) 는 BAT-δ).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/application/test_holding_divergence.py

@@ -0,0 +1,72 @@
+"""dcy-020 / REQ-062 (BAT-029): core holding ↔ broker divergence reconcile."""
+from __future__ import annotations
+
+from datetime import date
+
+from trex_core.application.broker_port import BalanceItem
+from trex_core.application.reconciliation import reconcile_core_holdings
+from trex_core.domain.slot import SlotService, SlotState
+from trex_core.domain.slot.in_memory_repository import InMemorySlotRepository
+
+DAY = date(2026, 6, 10)
+INST = "inst-1"
+
+
+class FakeBroker:
+    def __init__(self, balances):
+        self._b = balances
+    def name(self):  # noqa: D401
+        return "fake"
+    def submit_order(self, req): ...
+    def poll_fill(self, *a, **k): ...
+    def cancel_order(self, *a, **k): ...
+    def get_balance(self):
+        return list(self._b)
+
+
+def _hold(repo, svc, pid, symbol, qty):
+    repo.reconcile_universe(INST, DAY, {pid})
+    slot = repo.find_slot_by_portfolio(INST, pid)
+    svc.transit_slot(slot.slot_id, slot.status, SlotState.PENDING_BUY,
+                     reason="r", actor="a", symbol=symbol, qty=qty)
+    svc.transit_slot(slot.slot_id, SlotState.PENDING_BUY, SlotState.HOLDING,
+                     reason="r", actor="a", avg_price=70_000)
+    return repo.find_slot_by_portfolio(INST, pid)
+
+
+def _wire():
+    repo = InMemorySlotRepository()
+    return repo, SlotService(repo, instance_key=INST)
+
+
+def test_A_core_holding_broker_flat_goes_error():
+    repo, svc = _wire()
+    slot = _hold(repo, svc, "pf-a", "005930", 10)
+    broker = FakeBroker([])  # broker holds nothing
+    d = reconcile_core_holdings(slot_repo=repo, slot_service=svc, broker=broker, instance_key=INST)
+    assert d[str(slot.slot_id)] == "error"
+    assert repo.fetch_slot(slot.slot_id).status is SlotState.ERROR  # quarantined
+
+
+def test_C_qty_mismatch_warns_no_state_change():
+    repo, svc = _wire()
+    slot = _hold(repo, svc, "pf-a", "005930", 10)
+    broker = FakeBroker([BalanceItem(symbol="005930", hldg_qty=7)])  # mismatch
+    d = reconcile_core_holdings(slot_repo=repo, slot_service=svc, broker=broker, instance_key=INST)
+    assert d[str(slot.slot_id)] == "qty_warning"
+    assert repo.fetch_slot(slot.slot_id).status is SlotState.HOLDING  # unchanged
+
+
+def test_ok_when_qty_matches():
+    repo, svc = _wire()
+    slot = _hold(repo, svc, "pf-a", "005930", 10)
+    broker = FakeBroker([BalanceItem(symbol="005930", hldg_qty=10)])
+    d = reconcile_core_holdings(slot_repo=repo, slot_service=svc, broker=broker, instance_key=INST)
+    assert d[str(slot.slot_id)] == "ok"
+
+
+def test_B_broker_holds_unmanaged_warns():
+    repo, svc = _wire()
+    broker = FakeBroker([BalanceItem(symbol="000660", hldg_qty=5)])  # core has none
+    d = reconcile_core_holdings(slot_repo=repo, slot_service=svc, broker=broker, instance_key=INST)
+    assert d["broker:000660"] == "unmanaged_warning"