Forward ledger venue provenance to Portfolio Hub (#99)

Co-authored-by: Hermes Agent <noreply@nousresearch.com>

docs/interface-contract.md

@@ -4,8 +4,8 @@
 - Baseline Seed: .stage-pilot/bootstrap/baseline.yaml
 - Status: draft
 - Owner: project maintainers
-- Last Updated (KST): 2026-07-15 (BAT-057 — operator broker truth hotfix baseline alignment)
-- Source Discovery / Batch: bootstrap-baseline (pre-Discovery); HTTP API = dcy-002 / BAT-002; operator broker truth = dcy-037 / BAT-057
+- Last Updated (KST): 2026-09-19 (portfolio-hub Issue #32 venue provenance transport mapping)
+- Source Discovery / Batch: bootstrap-baseline (pre-Discovery); HTTP API = dcy-002 / BAT-002; operator broker truth = dcy-037 / BAT-057; ledger venue transport = portfolio-hub ProofLine req-0009
 - Primary Runtime: daemon (HTTP API) + library (slot 도메인)
 
 ## Project Summary
@@ -259,6 +259,23 @@ resume_kill_switch 요청·응답 (REQ-046):
 | GET | `/v1/auth/whoami` | `{daemon_id: str, ...}` |
 | GET | `/v1/portfolios?managed_by_daemon_id=<id>` | `{items: [PortfolioItem, ...]}` 또는 list root |
 
+## Interface: `LedgerPort` → portfolio-hub trade write (BAT-006; portfolio-hub REQ-0009)
+
+- Type: external-service (HTTP, portfolio-hub)
+- Consumers / Producers: `LedgerWriter`(소비) → `PortfolioHubLedger`(transport adapter) → portfolio-hub
+- Purpose: durable `LedgerTrade`를 `POST /v1/portfolios/{portfolio_id}/ledger/trades` 요청으로 직렬화한다.
+
+### Venue Provenance Mapping
+
+| Core field | HTTP request field | Contract |
+|---|---|---|
+| `LedgerTrade.venue` | `execution_venue` | 실제 체결 venue. `KRX`, `NXT`, `null`; `SOR` 금지 |
+| `LedgerTrade.order_venue` | `order_venue` | 원래 주문 routing venue. `KRX`, `NXT`, `SOR` |
+
+- `PortfolioHubLedger._payload()`는 두 값을 그대로 전달하며 `order_venue`에서 `execution_venue`를 추론하지 않는다.
+- Core producer, `LedgerTrade` domain model, durable outbox schema와 broker-routing 동작은 변경하지 않는다. 기존 outbox가 보존한 두 필드가 HTTP 경계에서 누락되지 않도록 하는 transport mapping이다.
+- Rollout 순서: nullable fields를 수용하는 portfolio-hub API/migration을 먼저 또는 동시에 배포한 뒤 이 adapter를 배포한다. 구형 Core가 두 필드를 보내지 않는 mixed-version 요청은 Hub에서 `null`로 수용한다.
+
 ## Interface: `SnapshotStore` + `PauseStore` + `SnapshotScheduler` (Protocol, BAT-008)
 
 - Type: internal-service