feat(ledger): dcy-018 option D cash/position write-back + 추정 현금 (BAT-023)

ledger write 응답의 portfolio-hub 권위 cash/quantity 를 스냅샷에 write-back 해
매수/매도 직후 "수량 live·현금 stale" 비대칭 제거(option D 활성화). portfolio-hub#8
(*_after 응답) 동작 중 확인으로 그간 deferred 됐던 REQ-030 을 닫음.

거버넌스: 전부 change-req (신규 REQ 없음, dcy-018 OQ-3 a).
- REQ-017: record_trade → LedgerWriteOutcome{result, cash_balance_after,
  asset_quantity_after}. 어댑터가 응답 root flat *_after 파싱(new+duplicate, 누락 None)
- REQ-019: LedgerWriter 에 SnapshotStore 주입 → new+duplicate write-back
  (best-effort, *_after 절대값이라 멱등). LedgerOutbox.pending_cash_delta()
- REQ-029: 추정 현금 오버레이(_apply_cash_estimate, cash_estimated 라벨, OQ-4 i)
  + 슬롯 오버레이 유지(OQ-1 B). 미정산 outbox delta 기반, write-back 수렴
- REQ-030: option D 활성화 → Approved→Implemented

best-effort 격리(NFR-1): write-back/추정 실패가 ledger 멱등·청산 무차단.
배치 번호: 동시 커밋된 BAT-022(slot-state, dcy-016)와 충돌해 BAT-023 으로 배정.

검증: 단위 350 passed/35 skipped, 인프라 게이트(PG+RabbitMQ) 385 passed, ruff clean.
신규 test_ledger_option_d + adapter/PG 테스트. BAT-023 release-candidate.

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

tests/adapters/ledger/test_portfolio_hub_ledger.py

@@ -13,6 +13,7 @@ from trex_core.application.ledger_port import (
     LedgerPermanentError,
     LedgerRetryableError,
     LedgerTrade,
+    LedgerWriteResult,
 )
 
 
@@ -90,6 +91,39 @@ def test_client_errors_are_permanent(status):
         adapter.record_trade(_trade())
 
 
+def test_outcome_parses_cash_quantity_after_on_new():
+    """dcy-018 / REQ-017: option D authoritative cash/quantity from 201 response."""
+    def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(201, json={"cash_balance_after": 300000.0,
+                                         "asset_quantity_after": 10})
+
+    out = PortfolioHubLedger("https://portfolio-hub.test", client=_client(handler)).record_trade(_trade())
+    assert out.result is LedgerWriteResult.NEW
+    assert out.cash_balance_after == 300000.0 and out.asset_quantity_after == 10.0
+
+
+def test_outcome_parses_after_on_duplicate():
+    """duplicate(200) also carries current authoritative values (OQ-2 b)."""
+    def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(200, json={"duplicate": True,
+                                         "cash_balance_after": 50000.0,
+                                         "asset_quantity_after": 3})
+
+    out = PortfolioHubLedger("https://portfolio-hub.test", client=_client(handler)).record_trade(_trade())
+    assert out.result is LedgerWriteResult.DUPLICATE_OK
+    assert out.cash_balance_after == 50000.0 and out.asset_quantity_after == 3.0
+
+
+def test_outcome_after_none_when_response_omits():
+    """Older hub without *_after → None → write-back skipped downstream."""
+    def handler(request: httpx.Request) -> httpx.Response:
+        return httpx.Response(201, json={"ok": True})
+
+    out = PortfolioHubLedger("https://portfolio-hub.test", client=_client(handler)).record_trade(_trade())
+    assert out.result is LedgerWriteResult.NEW
+    assert out.cash_balance_after is None and out.asset_quantity_after is None
+
+
 def test_429_stays_retryable():
     """dcy-015 / REQ-017: rate-limit is transient → retryable (not permanent)."""
     def handler(request: httpx.Request) -> httpx.Response:

tests/adapters/persistence/test_postgresql_ledger_outbox.py

@@ -89,6 +89,16 @@ def test_writer_marks_delivery_failed_permanent_on_pg(pg_clean):
     assert outbox.list_pending() == []
 
 
+def test_pending_cash_delta_on_pg(pg_clean):
+    """dcy-018 / REQ-029: estimated cash delta of pending rows summed by asset (SQL)."""
+    outbox = PostgreSQLLedgerOutbox(pg_clean)
+    outbox.enqueue(LedgerTrade(asset_id="PF-1", order_id="O-1", execution_id="cd-buy",
+                               side="buy", qty=10, price=1000.0, fee=1.0, tax=0.0,
+                               executed_at=datetime(2026, 6, 4, tzinfo=timezone.utc)))
+    deltas = outbox.pending_cash_delta()
+    assert deltas["PF-1"] == -(10 * 1000.0 + 1.0)  # buy => cash down by notional+fee
+
+
 def test_backoff_row_skipped_by_pending_scan_on_pg(pg_clean):
     """dcy-015 / REQ-019: a future next_retry_at excludes the row from list_pending."""
     outbox = PostgreSQLLedgerOutbox(pg_clean)