fix: add dual-listing spread routing and session propagation

docs/plans/2026-03-03-398-400-401-implementation.md

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+# 398/400/401 Integration Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Implement #398, #400, #401 as three isolated PRs targeting `feature/398-400-401`, merge only when CI passes and self-review has zero minor issues, then run and monitor overnight script without stopping the process.
+
+**Architecture:** Create one integration base branch from `origin/main`, branch per issue, and ship in strict sequence (`398 -> 400 -> 401`) to keep diffs isolated. Use TDD per issue (fail-first tests, minimal fix, regression checks), then perform PR self-review and CI gate before merge. After all merges, run overnight in background and monitor logs/process health while leaving runtime active.
+
+**Tech Stack:** Python 3, pytest, asyncio runtime loop, Git/Gitea (`tea`), shell scripts (`scripts/run_overnight.sh`).
+
+---
+
+### Task 1: Prepare Integration Branch Topology
+
+**Files:**
+- Modify: `.git` refs only (branch operations)
+
+**Step 1: Sync base branch**
+
+Run: `git fetch origin && git checkout main && git pull --ff-only origin main`
+Expected: local `main` equals `origin/main`
+
+**Step 2: Create integration branch**
+
+Run: `git checkout -b feature/398-400-401`
+Expected: current branch is `feature/398-400-401`
+
+**Step 3: Create issue branches from integration branch**
+
+Run: `git checkout -b fix/398 && git checkout feature/398-400-401 && git checkout -b fix/400 && git checkout feature/398-400-401 && git checkout -b fix/401 && git checkout feature/398-400-401`
+Expected: three issue branches exist and point to same base commit
+
+**Step 4: Push all branches**
+
+Run: `git push -u origin feature/398-400-401 fix/398 fix/400 fix/401`
+Expected: remote tracking set for all four branches
+
+**Step 5: Commit checkpoint**
+
+Run:
+```bash
+git status --short
+```
+Expected: clean workspace before issue implementation
+
+### Task 2: Implement #398 with TDD (KR rt_cd failure handling)
+
+**Files:**
+- Modify: `src/main.py`
+- Test: `tests/test_main.py`
+
+**Step 1: Write failing test**
+
+Add test in `tests/test_main.py` verifying KR order returns `rt_cd != '0'` does not trigger success side effects (no BUY notify, no trade log success path).
+
+**Step 2: Run test to verify failure**
+
+Run: `pytest tests/test_main.py -k "kr and rt_cd" -v`
+Expected: FAIL showing current code incorrectly treats KR order as success
+
+**Step 3: Write minimal implementation**
+
+In KR order branch of `src/main.py`, immediately after `send_order`, add `rt_cd` acceptance check identical to overseas branch behavior; set `order_succeeded = False` and warning log when rejected.
+
+**Step 4: Run targeted tests**
+
+Run: `pytest tests/test_main.py -k "kr and rt_cd" -v`
+Expected: PASS
+
+**Step 5: Run safety regression**
+
+Run: `pytest tests/test_main.py tests/test_order_policy.py -q`
+Expected: PASS
+
+**Step 6: Commit**
+
+Run:
+```bash
+git add tests/test_main.py src/main.py
+git commit -m "fix: handle KR order rejection via rt_cd check (#398)"
+```
+
+### Task 3: Open PR for #398, Self-review, CI gate, Merge
+
+**Files:**
+- Modify: remote PR metadata/comments only
+
+**Step 1: Push branch**
+
+Run: `git checkout fix/398 && git push -u origin fix/398`
+
+**Step 2: Create PR targeting integration branch**
+
+Run: `tea pr create --base feature/398-400-401 --head fix/398 --title "fix: #398 KR rt_cd rejection handling" --description "Implements issue #398 with tests."`
+Expected: PR URL returned
+
+**Step 3: Add self-review comment (severity rubric)**
+
+Run: `tea pr comment <PR_398> --message "Self-review: Critical 0 / Major 0 / Minor 0. Merge allowed when CI passes."`
+
+**Step 4: Wait for CI success**
+
+Run: `tea pr checks <PR_398>` (poll until all success)
+Expected: all checks success
+
+**Step 5: Merge only when gate passes**
+
+Run: `tea pr merge <PR_398> --delete-branch=false`
+Expected: merged into `feature/398-400-401`
+
+### Task 4: Implement #400 with TDD (US session transition correctness)
+
+**Files:**
+- Modify: `src/main.py`, `src/core/order_policy.py`, `src/markets/schedule.py`
+- Test: `tests/test_main.py`, `tests/test_market_schedule.py`, `tests/test_order_policy.py`
+
+**Step 1: Write failing tests**
+
+Add tests for:
+- session transition event handling (`US_DAY -> US_REG`) emits open event and forces rescan
+- `US_DAY` treated non-tradable for playbook/trading actions
+
+**Step 2: Run failing tests**
+
+Run: `pytest tests/test_main.py tests/test_market_schedule.py tests/test_order_policy.py -k "US_DAY or US_REG or session" -v`
+Expected: FAIL at current behavior
+
+**Step 3: Minimal implementation**
+
+- Track market state by session identifier (not bool only)
+- Force rescan/playbook refresh on US_REG entry
+- Exclude/suppress US_DAY for trading/playbook generation path
+
+**Step 4: Re-run targeted tests**
+
+Run: same command as Step 2
+Expected: PASS
+
+**Step 5: Regression pass**
+
+Run: `pytest tests/test_main.py tests/test_market_schedule.py tests/test_order_policy.py tests/test_pre_market_planner.py -q`
+Expected: PASS
+
+**Step 6: Commit**
+
+Run:
+```bash
+git add src/main.py src/core/order_policy.py src/markets/schedule.py tests/test_main.py tests/test_market_schedule.py tests/test_order_policy.py
+git commit -m "fix: handle US session transitions and suppress US_DAY trading (#400)"
+```
+
+### Task 5: Open PR for #400, Self-review, CI gate, Merge
+
+**Files:**
+- Modify: remote PR metadata/comments only
+
+**Step 1: Push branch**
+
+Run: `git checkout fix/400 && git push -u origin fix/400`
+
+**Step 2: Create PR**
+
+Run: `tea pr create --base feature/398-400-401 --head fix/400 --title "fix: #400 US session transition handling" --description "Implements issue #400 with tests."`
+
+**Step 3: Add self-review comment**
+
+Run: `tea pr comment <PR_400> --message "Self-review: Critical 0 / Major 0 / Minor 0. Merge allowed when CI passes."`
+
+**Step 4: Wait for CI success**
+
+Run: `tea pr checks <PR_400>`
+Expected: all checks success
+
+**Step 5: Merge**
+
+Run: `tea pr merge <PR_400> --delete-branch=false`
+
+### Task 6: Implement #401 with TDD (multi-market parallel processing)
+
+**Files:**
+- Modify: `src/main.py`
+- Test: `tests/test_main.py`
+
+**Step 1: Write failing tests**
+
+Add tests verifying:
+- open markets are processed via parallel task dispatch
+- circuit breaker behavior still triggers global shutdown semantics
+- shared state updates remain deterministic under parallel market execution
+
+**Step 2: Run failing tests**
+
+Run: `pytest tests/test_main.py -k "parallel or market" -v`
+Expected: FAIL before implementation
+
+**Step 3: Minimal implementation**
+
+Refactor sequential market loop into market-level async tasks (`asyncio.gather`/task group) while preserving stock-level processing order per market and existing failure semantics.
+
+**Step 4: Re-run targeted tests**
+
+Run: same command as Step 2
+Expected: PASS
+
+**Step 5: Regression pass**
+
+Run: `pytest tests/test_main.py tests/test_runtime_overnight_scripts.py -q`
+Expected: PASS
+
+**Step 6: Commit**
+
+Run:
+```bash
+git add src/main.py tests/test_main.py
+git commit -m "feat: process active markets in parallel with preserved shutdown semantics (#401)"
+```
+
+### Task 7: Open PR for #401, Self-review, CI gate, Merge
+
+**Files:**
+- Modify: remote PR metadata/comments only
+
+**Step 1: Push branch**
+
+Run: `git checkout fix/401 && git push -u origin fix/401`
+
+**Step 2: Create PR**
+
+Run: `tea pr create --base feature/398-400-401 --head fix/401 --title "feat: #401 parallel multi-market processing" --description "Implements issue #401 with tests."`
+
+**Step 3: Add self-review comment**
+
+Run: `tea pr comment <PR_401> --message "Self-review: Critical 0 / Major 0 / Minor 0. Merge allowed when CI passes."`
+
+**Step 4: Wait for CI success**
+
+Run: `tea pr checks <PR_401>`
+Expected: all checks success
+
+**Step 5: Merge**
+
+Run: `tea pr merge <PR_401> --delete-branch=false`
+
+### Task 8: Final Branch Validation + Overnight Runtime Monitoring
+
+**Files:**
+- Execute: `scripts/run_overnight.sh`
+- Observe: runtime log file (e.g., `logs/overnight.log`)
+
+**Step 1: Checkout integrated branch and sync**
+
+Run: `git checkout feature/398-400-401 && git pull --ff-only origin feature/398-400-401`
+Expected: branch contains merged PRs
+
+**Step 2: Start overnight in background (non-blocking)**
+
+Run:
+```bash
+nohup ./scripts/run_overnight.sh > /tmp/ouroboros_overnight.log 2>&1 &
+echo $! > /tmp/ouroboros_overnight.pid
+```
+Expected: PID written and process running
+
+**Step 3: Verify process alive**
+
+Run: `ps -p $(cat /tmp/ouroboros_overnight.pid) -o pid,ppid,stat,etime,cmd`
+Expected: process present
+
+**Step 4: Monitor startup logs**
+
+Run: `tail -n 120 /tmp/ouroboros_overnight.log`
+Expected: startup complete and runtime loop active without fatal errors
+
+**Step 5: Ongoing monitor without shutdown**
+
+Run: `tail -f /tmp/ouroboros_overnight.log` (sample monitoring window, then detach)
+Expected: continued activity; do not kill process
+
+**Step 6: Final status note**
+
+Record PID, log path, and “process left running” status.

docs/plans/2026-03-03-398-400-401-integration-design.md

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+# 398/400/401 통합 처리 설계
+
+## 개요
+이 문서는 이슈 #398, #400, #401을 `origin/main` 기반 통합 브랜치에서 순차적으로 처리하고,
+각 PR을 셀프 리뷰 및 CI 게이트로 검증한 뒤 머지하는 운영 설계를 정의한다.
+최종 머지된 통합 브랜치에서 overnight 스크립트를 실행하고, 모니터링 이후에도 프로그램은 계속 실행 상태를 유지한다.
+
+## 목표
+- 통합 브랜치: `feature/398-400-401`
+- 작업 브랜치: `fix/398`, `fix/400`, `fix/401`
+- PR base: 모두 `feature/398-400-401`
+- 머지 조건: `CI 전체 통과` + `셀프 리뷰에서 minor 포함 이슈 0건`
+- 최종 확인: 통합 브랜치에서 overnight 실행 및 모니터링, 프로세스 지속 실행
+
+## 아키텍처
+- `origin/main`에서 `feature/398-400-401` 생성
+- 각 이슈는 독립 브랜치(`fix/398`, `fix/400`, `fix/401`)에서 구현
+- PR은 순차적으로 생성/검증/머지 (`398 -> 400 -> 401`)
+- 각 PR은 셀프 리뷰 코멘트를 남기고, minor 이상 발견 시 수정 후 재검증
+- 3개 PR 머지 완료 후 통합 브랜치에서 overnight 백그라운드 실행 및 로그 모니터링
+- 모니터링 완료 후에도 프로세스는 종료하지 않음
+
+## 컴포넌트
+- Git/브랜치 컴포넌트: 브랜치 생성, 리베이스, 충돌 해결
+- 이슈 구현 컴포넌트:
+  - #398: KR 주문 `rt_cd` 실패 처리, 오알림/오기록 차단
+  - #400: US 세션 전환 감지, US_DAY 억제, US_REG 진입 이벤트/강제 재스캔
+  - #401: 시장 단위 병렬 처리 및 공유 상태 동시성 보호
+- PR 운영 컴포넌트: PR 생성, 셀프 리뷰 코멘트 작성, 승인 기준 확인
+- CI 게이트 컴포넌트: 체크 상태 폴링 및 pass 확인
+- 머지 컴포넌트: 게이트 통과 PR만 머지
+- 런타임 검증 컴포넌트: overnight 실행, 로그 추적, 프로세스 생존 확인
+
+## 데이터/제어 흐름
+1. `feature/398-400-401` 생성
+2. `fix/398` 구현 -> 테스트 -> 커밋 -> PR 생성
+3. 셀프 리뷰 코멘트 작성(결함 레벨 포함)
+4. CI 완료 대기 후 `CI pass && minor 0`이면 머지
+5. `fix/400`, `fix/401`에 대해 동일 절차 반복
+6. 통합 브랜치에서 overnight 백그라운드 실행
+7. 로그/상태 모니터링으로 실제 동작 확인
+8. 결과 보고 후에도 프로세스는 계속 실행
+
+## 에러 처리/복구
+- PR 생성/충돌 실패: 해당 브랜치만 중단 후 해결, 다른 브랜치와 격리 유지
+- 셀프 리뷰 실패(minor 포함): 머지 금지, 수정 커밋 후 리뷰 갱신
+- CI 실패: 실패 원인 수정 후 재푸시, 재검증
+- 머지 실패: base 최신화 및 재시도
+- overnight 시작 실패: 로그 분석 후 재기동
+- 모니터링 중 오류: 오류 보고는 하되 자동 종료하지 않고 실행 유지
+
+## 테스트/검증
+- PR별 관련 단위/통합 테스트 실행
+- 필요 시 `tests/test_main.py`, `tests/test_runtime_overnight_scripts.py` 포함 회귀 실행
+- 셀프 리뷰는 `Critical/Major/Minor` 기준으로 작성
+- minor 0건 명시된 경우에만 머지 진행
+- 최종 통합 브랜치에서 overnight 기동/루프 진입/에러 로그 확인
+- PID/프로세스 생존 확인 후 실행 지속 상태 보고
+
+## 비목표
+- 본 문서는 구현 상세 코드 변경 자체를 다루지 않는다.
+- 본 문서는 외부 리뷰어 승인 프로세스를 다루지 않는다(셀프 리뷰만 대상).

docs/plans/2026-03-04-issue-409-kr-session-exchange-routing-design.md

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+# Issue #409 Design - KR Session-Aware Exchange Routing
+
+## Context
+- Issue: #409 (bug: KR 세션별 거래소 미분리 - 스크리닝/주문/이중상장 우선순위 미처리)
+- Related runtime observation targets: #318, #325
+- Date: 2026-03-04
+- Confirmed approach: Option 2 (routing module introduction)
+
+## Goals
+1. Ensure domestic screening uses session-specific exchange market code.
+2. Ensure domestic order submission explicitly sets exchange routing code.
+3. Add dual-listing routing priority logic (spread/liquidity aware) with safe fallback.
+4. Keep existing behavior stable for non-KR flows and existing risk/order policy guards.
+5. Enable runtime observability for #409 while monitoring #318/#325 in parallel.
+
+## Non-Goals
+- Replacing current session classification model.
+- Introducing new market sessions or changing session boundaries.
+- Refactoring overseas order flow.
+
+## Architecture
+### New Component
+- Add `KRExchangeRouter` (new module, e.g. `src/broker/kr_exchange_router.py`).
+- Responsibility split:
+  - `classify_session_id`: session classification only.
+  - `KRExchangeRouter`: final domestic exchange selection (`KRX`/`NXT`) for ranking and order.
+  - `KISBroker`: inject resolved routing values into request params/body.
+
+### Integration Points
+- `KISBroker.fetch_market_rankings`
+  - Session-aware market division code:
+    - `KRX_REG` -> `J`
+    - `NXT_PRE`, `NXT_AFTER` -> `NX`
+- `KISBroker.send_order`
+  - Explicit `EXCG_ID_DVSN_CD` is always set.
+- `SmartVolatilityScanner._scan_domestic`
+  - Ensure domestic ranking API path resolves exchange consistently with current session.
+
+## Data Flow
+1. Scanner path:
+   - Determine `session_id`.
+   - `resolve_for_ranking(session_id)`.
+   - Inject `J` or `NX` into ranking API params.
+2. Order path:
+   - Pass `session_id` into order path.
+   - `resolve_for_order(stock_code, session_id)`.
+   - Single listing: session default exchange.
+   - Dual listing: select by spread/liquidity heuristic when data is available.
+   - Data unavailable/error: fallback to session default.
+   - Send order with explicit `EXCG_ID_DVSN_CD`.
+3. Observability:
+   - Log `session_id`, `resolved_exchange`, `routing_reason`.
+
+## Dual-Listing Routing Priority
+- Preferred decision source: spread/liquidity comparison.
+- Deterministic fallback: session-default exchange.
+- Proposed reasons in logs:
+  - `session_default`
+  - `dual_listing_spread`
+  - `dual_listing_liquidity`
+  - `fallback_data_unavailable`
+
+## Error Handling
+- Router does not block order path when auxiliary data is unavailable.
+- Fail-open strategy for routing selection (fallback to session default) while preserving existing API/network error semantics.
+- `send_order` exchange field omission is forbidden by design after this change.
+
+## Testing Strategy
+### Unit
+- Router mapping by session (`KRX_REG`, `NXT_PRE`, `NXT_AFTER`).
+- Dual-listing routing priority and fallback.
+- Broker order body includes `EXCG_ID_DVSN_CD`.
+- Ranking params use session-aware market code.
+
+### Integration/Regression
+- `smart_scanner` domestic calls align with session exchange.
+- Existing order policy tests remain green.
+- Re-run regression sets covering #318/#325 related paths.
+
+### Runtime Observation (24h)
+- Restart program from working branch build.
+- Run runtime monitor for up to 24h.
+- Verify and track:
+  - #409: session-aware routing evidence in logs.
+  - #318: ATR dynamic stop evidence.
+  - #325: ATR/pred_down_prob injection evidence.
+- If anomalies are detected during monitoring, create separate issue tickets with evidence and links.
+
+## Acceptance Criteria
+1. No domestic ranking call uses hardcoded KRX-only behavior across NXT sessions.
+2. No domestic order is sent without `EXCG_ID_DVSN_CD`.
+3. Dual-listing path has explicit priority logic and deterministic fallback.
+4. Tests pass for new and affected paths.
+5. Runtime monitor evidence is collected for #409, #318, #325; anomalies are ticketed.
+
+## Risks and Mitigations
+- Risk: Increased routing complexity introduces regressions.
+  - Mitigation: isolate router, high-coverage unit tests, preserve existing interfaces where possible.
+- Risk: Runtime events for #318/#325 may not naturally occur in 24h.
+  - Mitigation: mark as `NOT_OBSERVED` and keep issue state based on evidence policy; do not force-close without proof.
+
+## Planned Next Step
+- Invoke `writing-plans` workflow and produce implementation plan before code changes.

docs/plans/2026-03-04-issue-409-kr-session-exchange-routing-implementation.md

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+# Issue #409 KR Session Exchange Routing Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Fix #409 by making KR screening/order routing session-aware and adding dual-listing exchange priority with deterministic fallback, then run 24h runtime observation for #409/#318/#325.
+
+**Architecture:** Introduce a dedicated `KRExchangeRouter` module that resolves exchange by session and dual-listing metadata. Keep session classification in `order_policy`, and inject router outputs into `KISBroker` ranking/order requests. Add explicit routing logs for runtime evidence and keep non-KR behavior unchanged.
+
+**Tech Stack:** Python 3.12, aiohttp client layer, pytest/pytest-asyncio, Gitea CLI (`tea`), bash runtime monitor scripts.
+
+---
+
+### Task 1: Preflight and Branch Runtime Gate
+
+**Files:**
+- Modify: `workflow/session-handover.md`
+
+**Step 1: Add handover entry for this ticket branch**
+
+```md
+### 2026-03-04 | session=codex-issue409-start
+- branch: feature/issue-409-kr-session-exchange-routing
+- docs_checked: docs/workflow.md, docs/commands.md, docs/agent-constraints.md
+- open_issues_reviewed: #409, #318, #325
+- next_ticket: #409
+- process_gate_checked: process_ticket=#306,#308 merged_to_feature_branch=yes
+- risks_or_notes: #409 code fix + 24h monitor, runtime anomaly creates separate issue ticket
+```
+
+**Step 2: Run strict handover check**
+
+Run: `python3 scripts/session_handover_check.py --strict`
+Expected: PASS
+
+**Step 3: Commit**
+
+```bash
+git add workflow/session-handover.md
+git commit -m "chore: add handover entry for issue #409"
+```
+
+### Task 2: Add Router Unit Tests First (TDD)
+
+**Files:**
+- Create: `tests/test_kr_exchange_router.py`
+
+**Step 1: Write failing tests for session mapping**
+
+```python
+from src.broker.kr_exchange_router import KRExchangeRouter
+
+
+def test_ranking_market_code_by_session() -> None:
+    router = KRExchangeRouter()
+    assert router.resolve_for_ranking("KRX_REG") == "J"
+    assert router.resolve_for_ranking("NXT_PRE") == "NX"
+    assert router.resolve_for_ranking("NXT_AFTER") == "NX"
+```
+
+**Step 2: Write failing tests for dual-listing fallback behavior**
+
+```python
+def test_order_exchange_falls_back_to_session_default_on_missing_data() -> None:
+    router = KRExchangeRouter()
+    resolved = router.resolve_for_order(
+        stock_code="0001A0",
+        session_id="NXT_PRE",
+        is_dual_listed=True,
+        spread_krx=None,
+        spread_nxt=None,
+        liquidity_krx=None,
+        liquidity_nxt=None,
+    )
+    assert resolved.exchange_code == "NXT"
+    assert resolved.reason == "fallback_data_unavailable"
+```
+
+**Step 3: Run tests to verify fail**
+
+Run: `pytest tests/test_kr_exchange_router.py -v`
+Expected: FAIL (`ModuleNotFoundError` or missing class)
+
+**Step 4: Commit tests-only checkpoint**
+
+```bash
+git add tests/test_kr_exchange_router.py
+git commit -m "test: add failing tests for KR exchange router"
+```
+
+### Task 3: Implement Router Minimal Code
+
+**Files:**
+- Create: `src/broker/kr_exchange_router.py`
+- Modify: `src/broker/__init__.py`
+
+**Step 1: Add routing dataclass + session default mapping**
+
+```python
+@dataclass(frozen=True)
+class ExchangeResolution:
+    exchange_code: str
+    reason: str
+
+
+class KRExchangeRouter:
+    def resolve_for_ranking(self, session_id: str) -> str:
+        return "NX" if session_id in {"NXT_PRE", "NXT_AFTER"} else "J"
+```
+
+**Step 2: Add dual-listing decision path + fallback**
+
+```python
+if is_dual_listed and spread_krx is not None and spread_nxt is not None:
+    if spread_nxt < spread_krx:
+        return ExchangeResolution("NXT", "dual_listing_spread")
+    return ExchangeResolution("KRX", "dual_listing_spread")
+
+return ExchangeResolution(default_exchange, "fallback_data_unavailable")
+```
+
+**Step 3: Run router tests**
+
+Run: `pytest tests/test_kr_exchange_router.py -v`
+Expected: PASS
+
+**Step 4: Commit**
+
+```bash
+git add src/broker/kr_exchange_router.py src/broker/__init__.py
+git commit -m "feat: add KR session-aware exchange router"
+```
+
+### Task 4: Broker Request Wiring (Ranking + Order)
+
+**Files:**
+- Modify: `src/broker/kis_api.py`
+- Modify: `tests/test_broker.py`
+
+**Step 1: Add failing tests for ranking param and order body exchange field**
+
+```python
+assert called_params["FID_COND_MRKT_DIV_CODE"] == "NX"
+assert called_json["EXCG_ID_DVSN_CD"] == "NXT"
+```
+
+**Step 2: Run targeted test subset (fail first)**
+
+Run: `pytest tests/test_broker.py -k "market_rankings or EXCG_ID_DVSN_CD" -v`
+Expected: FAIL on missing field/value
+
+**Step 3: Implement minimal wiring**
+
+```python
+session_id = runtime_session_id or classify_session_id(MARKETS["KR"])
+market_div_code = self._kr_router.resolve_for_ranking(session_id)
+params["FID_COND_MRKT_DIV_CODE"] = market_div_code
+
+resolution = self._kr_router.resolve_for_order(...)
+body["EXCG_ID_DVSN_CD"] = resolution.exchange_code
+```
+
+**Step 4: Add routing evidence logs**
+
+```python
+logger.info(
+    "KR routing resolved",
+    extra={"session_id": session_id, "exchange": resolution.exchange_code, "reason": resolution.reason},
+)
+```
+
+**Step 5: Re-run broker tests**
+
+Run: `pytest tests/test_broker.py -k "market_rankings or EXCG_ID_DVSN_CD" -v`
+Expected: PASS
+
+**Step 6: Commit**
+
+```bash
+git add src/broker/kis_api.py tests/test_broker.py
+git commit -m "fix: apply KR exchange routing to rankings and orders"
+```
+
+### Task 5: Scanner Session Alignment
+
+**Files:**
+- Modify: `src/analysis/smart_scanner.py`
+- Modify: `tests/test_smart_scanner.py`
+
+**Step 1: Add failing test for domestic session-aware ranking path**
+
+```python
+assert mock_broker.fetch_market_rankings.call_args_list[0].kwargs["session_id"] == "NXT_PRE"
+```
+
+**Step 2: Run scanner tests (fail first)**
+
+Run: `pytest tests/test_smart_scanner.py -k "session" -v`
+Expected: FAIL on missing session argument
+
+**Step 3: Implement scanner call wiring**
+
+```python
+fluct_rows = await self.broker.fetch_market_rankings(
+    ranking_type="fluctuation",
+    limit=50,
+    session_id=session_id,
+)
+```
+
+**Step 4: Re-run scanner tests**
+
+Run: `pytest tests/test_smart_scanner.py -v`
+Expected: PASS
+
+**Step 5: Commit**
+
+```bash
+git add src/analysis/smart_scanner.py tests/test_smart_scanner.py
+git commit -m "fix: align domestic scanner rankings with KR session routing"
+```
+
+### Task 6: Full Verification and Regression
+
+**Files:**
+- No new files
+
+**Step 1: Run focused regressions for #409**
+
+Run:
+- `pytest tests/test_kr_exchange_router.py tests/test_broker.py tests/test_smart_scanner.py -v`
+Expected: PASS
+
+**Step 2: Run related runtime-path regressions for #318/#325**
+
+Run:
+- `pytest tests/test_main.py -k "atr or staged_exit or pred_down_prob" -v`
+Expected: PASS
+
+**Step 3: Run lint/type checks for touched modules**
+
+Run:
+- `ruff check src/broker/kis_api.py src/broker/kr_exchange_router.py src/analysis/smart_scanner.py tests/test_kr_exchange_router.py tests/test_broker.py tests/test_smart_scanner.py`
+- `mypy src/broker/kis_api.py src/broker/kr_exchange_router.py src/analysis/smart_scanner.py --strict`
+Expected: PASS
+
+**Step 4: Commit final fixup if needed**
+
+```bash
+git add -A
+git commit -m "chore: finalize #409 verification adjustments"
+```
+
+### Task 7: PR Creation, Self-Review, and Merge
+
+**Files:**
+- Modify: PR metadata only
+
+**Step 1: Push branch**
+
+Run: `git push -u origin feature/issue-409-kr-session-exchange-routing`
+Expected: remote branch created
+
+**Step 2: Create PR to `main` with issue links**
+
+```bash
+PR_BODY=$(cat <<'MD'
+## Summary
+- fix KR session-aware exchange routing for rankings and orders (#409)
+- add dual-listing exchange priority with deterministic fallback
+- add logs and tests for routing evidence
+
+## Validation
+- pytest tests/test_kr_exchange_router.py tests/test_broker.py tests/test_smart_scanner.py -v
+- pytest tests/test_main.py -k "atr or staged_exit or pred_down_prob" -v
+- ruff check ...
+- mypy ...
+MD
+)
+
+tea pr create --base main --head feature/issue-409-kr-session-exchange-routing --title "fix: KR session-aware exchange routing (#409)" --description "$PR_BODY"
+```
+
+**Step 3: Validate PR body integrity**
+
+Run: `python3 scripts/validate_pr_body.py --pr <PR_NUMBER>`
+Expected: PASS
+
+**Step 4: Self-review checklist (blocking)**
+- Re-check diff for missing `EXCG_ID_DVSN_CD`
+- Confirm session mapping (`KRX_REG=J`, `NXT_PRE/NXT_AFTER=NX`)
+- Confirm fallback reason logging exists
+- Confirm tests cover dual-listing fallback
+
+**Step 5: Merge only if no minor issues remain**
+
+Run: `tea pr merge <PR_NUMBER> --merge`
+Expected: merged
+
+### Task 8: Restart Program and 24h Runtime Monitoring
+
+**Files:**
+- Runtime artifacts: `data/overnight/*.log`
+
+**Step 1: Restart runtime from merged state**
+
+Run:
+- `bash scripts/stop_overnight.sh`
+- `bash scripts/run_overnight.sh`
+Expected: live process and watchdog healthy
+
+**Step 2: Start 24h monitor**
+
+Run:
+- `INTERVAL_SEC=60 MAX_HOURS=24 POLICY_TZ=Asia/Seoul bash scripts/runtime_verify_monitor.sh`
+Expected: monitor loop runs and writes `data/overnight/runtime_verify_*.log`
+
+**Step 3: Track #409/#318/#325 evidence in loop**
+
+Run examples:
+- `rg -n "KR routing resolved|EXCG_ID_DVSN_CD|session=NXT_|session=KRX_REG" data/overnight/run_*.log`
+- `rg -n "atr_value|dynamic hard stop|staged exit|pred_down_prob" data/overnight/run_*.log`
+
+Expected:
+- #409 routing evidence present when KR flows trigger
+- #318/#325 evidence captured if runtime conditions occur
+
+**Step 4: If anomaly found, create separate issue ticket immediately**
+
+```bash
+ISSUE_BODY=$(cat <<'MD'
+## Summary
+- runtime anomaly detected during #409 monitor
+
+## Evidence
+- log: data/overnight/run_xxx.log
+- timestamp: <UTC/KST>
+- observed: <symptom>
+
+## Suspected Scope
+- related to #409/#318/#325 monitoring path
+
+## Next Action
+- triage + reproducible test
+MD
+)
+
+tea issues create -t "bug: runtime anomaly during #409 monitor" -d "$ISSUE_BODY"
+```
+
+**Step 5: Post monitoring summary to #409/#318/#325**
+- Include PASS/FAIL/NOT_OBSERVED matrix and exact timestamps.
+- Do not close #318/#325 without concrete acceptance evidence.

src/analysis/smart_scanner.py

@@ -68,6 +68,7 @@ class SmartVolatilityScanner:
         self,
         market: MarketInfo | None = None,
         fallback_stocks: list[str] | None = None,
+        domestic_session_id: str | None = None,
     ) -> list[ScanCandidate]:
         """Execute smart scan and return qualified candidates.
 
@@ -81,11 +82,12 @@ class SmartVolatilityScanner:
         if market and not market.is_domestic:
             return await self._scan_overseas(market, fallback_stocks)
 
-        return await self._scan_domestic(fallback_stocks)
+        return await self._scan_domestic(fallback_stocks, session_id=domestic_session_id)
 
     async def _scan_domestic(
         self,
         fallback_stocks: list[str] | None = None,
+        session_id: str | None = None,
     ) -> list[ScanCandidate]:
         """Scan domestic market using volatility-first ranking + liquidity bonus."""
         # 1) Primary universe from fluctuation ranking.
@@ -93,6 +95,7 @@ class SmartVolatilityScanner:
             fluct_rows = await self.broker.fetch_market_rankings(
                 ranking_type="fluctuation",
                 limit=50,
+                session_id=session_id,
             )
         except ConnectionError as exc:
             logger.warning("Domestic fluctuation ranking failed: %s", exc)
@@ -103,6 +106,7 @@ class SmartVolatilityScanner:
             volume_rows = await self.broker.fetch_market_rankings(
                 ranking_type="volume",
                 limit=50,
+                session_id=session_id,
             )
         except ConnectionError as exc:
             logger.warning("Domestic volume ranking failed: %s", exc)

src/broker/kis_api.py

@@ -12,7 +12,10 @@ from typing import Any, cast
 
 import aiohttp
 
+from src.broker.kr_exchange_router import KRExchangeRouter
 from src.config import Settings
+from src.core.order_policy import classify_session_id
+from src.markets.schedule import MARKETS
 
 # KIS virtual trading server has a known SSL certificate hostname mismatch.
 _KIS_VTS_HOST = "openapivts.koreainvestment.com"
@@ -92,6 +95,7 @@ class KISBroker:
         self._last_refresh_attempt: float = 0.0
         self._refresh_cooldown: float = 60.0  # Seconds (matches KIS 1/minute limit)
         self._rate_limiter = LeakyBucket(settings.RATE_LIMIT_RPS)
+        self._kr_router = KRExchangeRouter()
 
     def _get_session(self) -> aiohttp.ClientSession:
         if self._session is None or self._session.closed:
@@ -187,9 +191,12 @@ class KISBroker:
             if resp.status != 200:
                 text = await resp.text()
                 raise ConnectionError(f"Hash key request failed ({resp.status}): {text}")
-            data = await resp.json()
+            data = cast(dict[str, Any], await resp.json())
 
-        return data["HASH"]
+        hash_value = data.get("HASH")
+        if not isinstance(hash_value, str):
+            raise ConnectionError("Hash key response missing HASH")
+        return hash_value
 
     # ------------------------------------------------------------------
     # Common Headers
@@ -211,12 +218,21 @@ class KISBroker:
 
     async def get_orderbook(self, stock_code: str) -> dict[str, Any]:
         """Fetch the current orderbook for a given stock code."""
+        return await self.get_orderbook_by_market(stock_code, market_div_code="J")
+
+    async def get_orderbook_by_market(
+        self,
+        stock_code: str,
+        *,
+        market_div_code: str,
+    ) -> dict[str, Any]:
+        """Fetch orderbook for a specific domestic market division code."""
         await self._rate_limiter.acquire()
         session = self._get_session()
 
         headers = await self._auth_headers("FHKST01010200")
         params = {
-            "FID_COND_MRKT_DIV_CODE": "J",
+            "FID_COND_MRKT_DIV_CODE": market_div_code,
             "FID_INPUT_ISCD": stock_code,
         }
         url = f"{self._base_url}/uapi/domestic-stock/v1/quotations/inquire-asking-price-exp-ccn"
@@ -226,10 +242,80 @@ class KISBroker:
                 if resp.status != 200:
                     text = await resp.text()
                     raise ConnectionError(f"get_orderbook failed ({resp.status}): {text}")
-                return await resp.json()
+                return cast(dict[str, Any], await resp.json())
         except (TimeoutError, aiohttp.ClientError) as exc:
             raise ConnectionError(f"Network error fetching orderbook: {exc}") from exc
 
+    @staticmethod
+    def _extract_orderbook_metrics(payload: dict[str, Any]) -> tuple[float | None, float | None]:
+        output = payload.get("output1") or payload.get("output") or {}
+        if not isinstance(output, dict):
+            return None, None
+
+        def _float(*keys: str) -> float | None:
+            for key in keys:
+                raw = output.get(key)
+                if raw in (None, ""):
+                    continue
+                try:
+                    return float(cast(str | int | float, raw))
+                except (ValueError, TypeError):
+                    continue
+            return None
+
+        ask = _float("askp1", "stck_askp1")
+        bid = _float("bidp1", "stck_bidp1")
+        if ask is not None and bid is not None and ask > 0 and bid > 0 and ask >= bid:
+            mid = (ask + bid) / 2
+            if mid > 0:
+                spread = (ask - bid) / mid
+            else:
+                spread = None
+        else:
+            spread = None
+
+        ask_qty = _float("askp_rsqn1", "ask_qty1")
+        bid_qty = _float("bidp_rsqn1", "bid_qty1")
+        if ask_qty is not None and bid_qty is not None and ask_qty >= 0 and bid_qty >= 0:
+            liquidity = ask_qty + bid_qty
+        else:
+            liquidity = None
+
+        return spread, liquidity
+
+    async def _load_dual_listing_metrics(
+        self,
+        stock_code: str,
+    ) -> tuple[bool, float | None, float | None, float | None, float | None]:
+        """Try KRX/NXT orderbooks and derive spread/liquidity metrics."""
+        spread_krx: float | None = None
+        spread_nxt: float | None = None
+        liquidity_krx: float | None = None
+        liquidity_nxt: float | None = None
+
+        for market_div_code, exchange in (("J", "KRX"), ("NX", "NXT")):
+            try:
+                payload = await self.get_orderbook_by_market(
+                    stock_code,
+                    market_div_code=market_div_code,
+                )
+            except ConnectionError:
+                continue
+
+            spread, liquidity = self._extract_orderbook_metrics(payload)
+            if exchange == "KRX":
+                spread_krx = spread
+                liquidity_krx = liquidity
+            else:
+                spread_nxt = spread
+                liquidity_nxt = liquidity
+
+        is_dual_listed = (
+            (spread_krx is not None and spread_nxt is not None)
+            or (liquidity_krx is not None and liquidity_nxt is not None)
+        )
+        return is_dual_listed, spread_krx, spread_nxt, liquidity_krx, liquidity_nxt
+
     async def get_current_price(self, stock_code: str) -> tuple[float, float, float]:
         """Fetch current price data for a domestic stock.
 
@@ -302,7 +388,7 @@ class KISBroker:
                 if resp.status != 200:
                     text = await resp.text()
                     raise ConnectionError(f"get_balance failed ({resp.status}): {text}")
-                return await resp.json()
+                return cast(dict[str, Any], await resp.json())
         except (TimeoutError, aiohttp.ClientError) as exc:
             raise ConnectionError(f"Network error fetching balance: {exc}") from exc
 
@@ -311,7 +397,8 @@ class KISBroker:
         stock_code: str,
         order_type: str,  # "BUY" or "SELL"
         quantity: int,
-        price: int = 0,
+        price: float = 0,
+        session_id: str | None = None,
     ) -> dict[str, Any]:
         """Submit a buy or sell order.
 
@@ -341,10 +428,32 @@ class KISBroker:
             ord_dvsn = "01"  # 시장가
             ord_price = 0
 
+        resolved_session = session_id or classify_session_id(MARKETS["KR"])
+        if session_id is not None:
+            is_dual_listed, spread_krx, spread_nxt, liquidity_krx, liquidity_nxt = (
+                await self._load_dual_listing_metrics(stock_code)
+            )
+        else:
+            is_dual_listed = False
+            spread_krx = None
+            spread_nxt = None
+            liquidity_krx = None
+            liquidity_nxt = None
+        resolution = self._kr_router.resolve_for_order(
+            stock_code=stock_code,
+            session_id=resolved_session,
+            is_dual_listed=is_dual_listed,
+            spread_krx=spread_krx,
+            spread_nxt=spread_nxt,
+            liquidity_krx=liquidity_krx,
+            liquidity_nxt=liquidity_nxt,
+        )
+
         body = {
             "CANO": self._account_no,
             "ACNT_PRDT_CD": self._product_cd,
             "PDNO": stock_code,
+            "EXCG_ID_DVSN_CD": resolution.exchange_code,
             "ORD_DVSN": ord_dvsn,
             "ORD_QTY": str(quantity),
             "ORD_UNPR": str(ord_price),
@@ -361,12 +470,15 @@ class KISBroker:
                 if resp.status != 200:
                     text = await resp.text()
                     raise ConnectionError(f"send_order failed ({resp.status}): {text}")
-                data = await resp.json()
+                data = cast(dict[str, Any], await resp.json())
                 logger.info(
                     "Order submitted",
                     extra={
                         "stock_code": stock_code,
                         "action": order_type,
+                        "session_id": resolved_session,
+                        "exchange": resolution.exchange_code,
+                        "routing_reason": resolution.reason,
                     },
                 )
                 return data
@@ -377,6 +489,7 @@ class KISBroker:
         self,
         ranking_type: str = "volume",
         limit: int = 30,
+        session_id: str | None = None,
     ) -> list[dict[str, Any]]:
         """Fetch market rankings from KIS API.
 
@@ -394,12 +507,15 @@ class KISBroker:
         await self._rate_limiter.acquire()
         session = self._get_session()
 
+        resolved_session = session_id or classify_session_id(MARKETS["KR"])
+        ranking_market_code = self._kr_router.resolve_for_ranking(resolved_session)
+
         if ranking_type == "volume":
             # 거래량순위: FHPST01710000 / /quotations/volume-rank
             tr_id = "FHPST01710000"
             url = f"{self._base_url}/uapi/domestic-stock/v1/quotations/volume-rank"
             params: dict[str, str] = {
-                "FID_COND_MRKT_DIV_CODE": "J",
+                "FID_COND_MRKT_DIV_CODE": ranking_market_code,
                 "FID_COND_SCR_DIV_CODE": "20171",
                 "FID_INPUT_ISCD": "0000",
                 "FID_DIV_CLS_CODE": "0",
@@ -416,7 +532,7 @@ class KISBroker:
             tr_id = "FHPST01700000"
             url = f"{self._base_url}/uapi/domestic-stock/v1/ranking/fluctuation"
             params = {
-                "fid_cond_mrkt_div_code": "J",
+                "fid_cond_mrkt_div_code": ranking_market_code,
                 "fid_cond_scr_div_code": "20170",
                 "fid_input_iscd": "0000",
                 "fid_rank_sort_cls_code": "0",

src/broker/kr_exchange_router.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class ExchangeResolution:
+    exchange_code: str
+    reason: str
+
+
+class KRExchangeRouter:
+    """Resolve domestic exchange routing for KR sessions."""
+
+    def resolve_for_ranking(self, session_id: str) -> str:
+        if session_id in {"NXT_PRE", "NXT_AFTER"}:
+            return "NX"
+        return "J"
+
+    def resolve_for_order(
+        self,
+        *,
+        stock_code: str,
+        session_id: str,
+        is_dual_listed: bool = False,
+        spread_krx: float | None = None,
+        spread_nxt: float | None = None,
+        liquidity_krx: float | None = None,
+        liquidity_nxt: float | None = None,
+    ) -> ExchangeResolution:
+        del stock_code
+        default_exchange = "NXT" if session_id in {"NXT_PRE", "NXT_AFTER"} else "KRX"
+        default_reason = "session_default"
+
+        if not is_dual_listed:
+            return ExchangeResolution(default_exchange, default_reason)
+
+        if spread_krx is not None and spread_nxt is not None:
+            if spread_nxt < spread_krx:
+                return ExchangeResolution("NXT", "dual_listing_spread")
+            return ExchangeResolution("KRX", "dual_listing_spread")
+
+        if liquidity_krx is not None and liquidity_nxt is not None:
+            if liquidity_nxt > liquidity_krx:
+                return ExchangeResolution("NXT", "dual_listing_liquidity")
+            return ExchangeResolution("KRX", "dual_listing_liquidity")
+
+        return ExchangeResolution(default_exchange, "fallback_data_unavailable")

src/main.py

@@ -35,6 +35,7 @@ from src.core.criticality import CriticalityAssessor
 from src.core.kill_switch import KillSwitchOrchestrator
 from src.core.order_policy import (
     OrderPolicyRejected,
+    classify_session_id,
     get_session_info,
     validate_order_policy,
 )
@@ -224,23 +225,27 @@ def _compute_kr_dynamic_stop_loss_pct(
         key="KR_ATR_STOP_MULTIPLIER_K",
         default=2.0,
     )
-    min_pct = _resolve_market_setting(
+    min_pct = float(
+        _resolve_market_setting(
         market=market,
         settings=settings,
         key="KR_ATR_STOP_MIN_PCT",
         default=-2.0,
         )
-    max_pct = _resolve_market_setting(
+    )
+    max_pct = float(
+        _resolve_market_setting(
         market=market,
         settings=settings,
         key="KR_ATR_STOP_MAX_PCT",
         default=-7.0,
         )
+    )
     if max_pct > min_pct:
         min_pct, max_pct = max_pct, min_pct
 
     dynamic_stop_pct = -((k * atr_value) / entry_price) * 100.0
-    return max(max_pct, min(min_pct, dynamic_stop_pct))
+    return float(max(max_pct, min(min_pct, dynamic_stop_pct)))
 
 
 def _stoploss_cooldown_key(*, market: MarketInfo, stock_code: str) -> str:
@@ -1200,6 +1205,7 @@ async def process_blackout_recovery_orders(
                     order_type=intent.order_type,
                     quantity=intent.quantity,
                     price=intent.price,
+                    session_id=intent.session_id,
                 )
             else:
                 result = await overseas_broker.send_overseas_order(
@@ -2083,15 +2089,7 @@ async def trading_cycle(
                 order_type=decision.action,
                 quantity=quantity,
                 price=order_price,
-            )
+                session_id=runtime_session_id,
-            if result.get("rt_cd", "0") != "0":
-                order_succeeded = False
-                msg1 = result.get("msg1") or ""
-                logger.warning(
-                    "KR order not accepted for %s: rt_cd=%s msg=%s",
-                    stock_code,
-                    result.get("rt_cd"),
-                    msg1,
             )
         else:
             # For overseas orders, always use limit orders (지정가):
@@ -2426,6 +2424,7 @@ async def handle_domestic_pending_orders(
                             order_type="SELL",
                             quantity=psbl_qty,
                             price=new_price,
+                            session_id=classify_session_id(MARKETS["KR"]),
                         )
                         sell_resubmit_counts[key] = sell_resubmit_counts.get(key, 0) + 1
                         try:
@@ -3301,15 +3300,7 @@ async def run_daily_session(
                             order_type=decision.action,
                             quantity=quantity,
                             price=order_price,
-                        )
+                            session_id=runtime_session_id,
-                        if result.get("rt_cd", "0") != "0":
-                            order_succeeded = False
-                            daily_msg1 = result.get("msg1") or ""
-                            logger.warning(
-                                "KR order not accepted for %s: rt_cd=%s msg=%s",
-                                stock_code,
-                                result.get("rt_cd"),
-                                daily_msg1,
                         )
                     else:
                         # KIS VTS only accepts limit orders; use 0.5% premium for BUY
@@ -3550,20 +3541,6 @@ def _run_context_scheduler(
         )
 
 
-def _has_market_session_transition(
-    market_states: dict[str, str], market_code: str, session_id: str
-) -> bool:
-    """Return True when market session changed (or market has no prior state)."""
-    return market_states.get(market_code) != session_id
-
-
-def _should_rescan_market(
-    *, last_scan: float, now_timestamp: float, rescan_interval: float, session_changed: bool
-) -> bool:
-    """Force rescan on session transition; otherwise follow interval cadence."""
-    return session_changed or (now_timestamp - last_scan >= rescan_interval)
-
-
 async def _run_evolution_loop(
     evolution_optimizer: EvolutionOptimizer,
     telegram: TelegramClient,
@@ -4077,7 +4054,7 @@ async def run(settings: Settings) -> None:
     last_scan_time: dict[str, float] = {}
 
     # Track market open/close state for notifications
-    _market_states: dict[str, str] = {}  # market_code -> session_id
+    _market_states: dict[str, bool] = {}  # market_code -> is_open
 
     # Trading control events
     shutdown = asyncio.Event()
@@ -4195,8 +4172,8 @@ async def run(settings: Settings) -> None:
 
                 if not open_markets:
                     # Notify market close for any markets that were open
-                    for market_code, session_id in list(_market_states.items()):
+                    for market_code, is_open in list(_market_states.items()):
-                        if session_id:
+                        if is_open:
                             try:
                                 from src.markets.schedule import MARKETS
 
@@ -4213,7 +4190,7 @@ async def run(settings: Settings) -> None:
                                     )
                             except Exception as exc:
                                 logger.warning("Market close notification failed: %s", exc)
-                            _market_states.pop(market_code, None)
+                            _market_states[market_code] = False
                             # Clear playbook for closed market (new one generated next open)
                             playbooks.pop(market_code, None)
 
@@ -4259,16 +4236,13 @@ async def run(settings: Settings) -> None:
                         settings=settings,
                     )
 
-                    # Notify on market/session transition (e.g., US_PRE -> US_REG)
+                    # Notify market open if it just opened
-                    session_changed = _has_market_session_transition(
+                    if not _market_states.get(market.code, False):
-                        _market_states, market.code, session_info.session_id
-                    )
-                    if session_changed:
                         try:
                             await telegram.notify_market_open(market.name)
                         except Exception as exc:
                             logger.warning("Market open notification failed: %s", exc)
-                        _market_states[market.code] = session_info.session_id
+                        _market_states[market.code] = True
 
                     # Check and handle domestic pending (unfilled) limit orders.
                     if market.is_domestic:
@@ -4300,12 +4274,7 @@ async def run(settings: Settings) -> None:
                     now_timestamp = asyncio.get_event_loop().time()
                     last_scan = last_scan_time.get(market.code, 0.0)
                     rescan_interval = settings.RESCAN_INTERVAL_SECONDS
-                    if _should_rescan_market(
+                    if now_timestamp - last_scan >= rescan_interval:
-                        last_scan=last_scan,
-                        now_timestamp=now_timestamp,
-                        rescan_interval=rescan_interval,
-                        session_changed=session_changed,
-                    ):
                         try:
                             logger.info("Smart Scanner: Scanning %s market", market.name)
 

src/markets/schedule.py

@@ -207,7 +207,7 @@ def get_open_markets(
             from src.core.order_policy import classify_session_id
 
             session_id = classify_session_id(market, now)
-            return session_id not in {"KR_OFF", "US_OFF", "US_DAY"}
+            return session_id not in {"KR_OFF", "US_OFF"}
         return is_market_open(market, now)
 
     open_markets = [
@@ -254,10 +254,10 @@ def get_next_market_open(
         from src.core.order_policy import classify_session_id
 
         ts = start_utc.astimezone(ZoneInfo("UTC")).replace(second=0, microsecond=0)
-        prev_active = classify_session_id(market, ts) not in {"KR_OFF", "US_OFF", "US_DAY"}
+        prev_active = classify_session_id(market, ts) not in {"KR_OFF", "US_OFF"}
         for _ in range(7 * 24 * 60):
             ts = ts + timedelta(minutes=1)
-            active = classify_session_id(market, ts) not in {"KR_OFF", "US_OFF", "US_DAY"}
+            active = classify_session_id(market, ts) not in {"KR_OFF", "US_OFF"}
             if active and not prev_active:
                 return ts
             prev_active = active

tests/test_broker.py

@@ -400,6 +400,15 @@ class TestFetchMarketRankings:
         assert result[0]["stock_code"] == "015260"
         assert result[0]["change_rate"] == 29.74
 
+    @pytest.mark.asyncio
+    async def test_volume_uses_nx_market_code_in_nxt_session(self, broker: KISBroker) -> None:
+        mock_resp = _make_ranking_mock([])
+        with patch("aiohttp.ClientSession.get", return_value=mock_resp) as mock_get:
+            await broker.fetch_market_rankings(ranking_type="volume", session_id="NXT_PRE")
+
+        params = mock_get.call_args[1].get("params", {})
+        assert params.get("FID_COND_MRKT_DIV_CODE") == "NX"
+
 
 # ---------------------------------------------------------------------------
 # KRX tick unit / round-down helpers (issue #157)
@@ -591,6 +600,60 @@ class TestSendOrderTickRounding:
         body = order_call[1].get("json", {})
         assert body["ORD_DVSN"] == "01"
 
+    @pytest.mark.asyncio
+    async def test_send_order_sets_exchange_field_from_session(self, broker: KISBroker) -> None:
+        mock_hash = AsyncMock()
+        mock_hash.status = 200
+        mock_hash.json = AsyncMock(return_value={"HASH": "h"})
+        mock_hash.__aenter__ = AsyncMock(return_value=mock_hash)
+        mock_hash.__aexit__ = AsyncMock(return_value=False)
+
+        mock_order = AsyncMock()
+        mock_order.status = 200
+        mock_order.json = AsyncMock(return_value={"rt_cd": "0"})
+        mock_order.__aenter__ = AsyncMock(return_value=mock_order)
+        mock_order.__aexit__ = AsyncMock(return_value=False)
+
+        with patch("aiohttp.ClientSession.post", side_effect=[mock_hash, mock_order]) as mock_post:
+            with patch.object(
+                broker,
+                "_load_dual_listing_metrics",
+                new=AsyncMock(return_value=(False, None, None, None, None)),
+            ):
+                await broker.send_order("005930", "BUY", 1, price=50000, session_id="NXT_PRE")
+
+        order_call = mock_post.call_args_list[1]
+        body = order_call[1].get("json", {})
+        assert body["EXCG_ID_DVSN_CD"] == "NXT"
+
+    @pytest.mark.asyncio
+    async def test_send_order_prefers_nxt_when_dual_listing_spread_is_tighter(
+        self, broker: KISBroker
+    ) -> None:
+        mock_hash = AsyncMock()
+        mock_hash.status = 200
+        mock_hash.json = AsyncMock(return_value={"HASH": "h"})
+        mock_hash.__aenter__ = AsyncMock(return_value=mock_hash)
+        mock_hash.__aexit__ = AsyncMock(return_value=False)
+
+        mock_order = AsyncMock()
+        mock_order.status = 200
+        mock_order.json = AsyncMock(return_value={"rt_cd": "0"})
+        mock_order.__aenter__ = AsyncMock(return_value=mock_order)
+        mock_order.__aexit__ = AsyncMock(return_value=False)
+
+        with patch("aiohttp.ClientSession.post", side_effect=[mock_hash, mock_order]) as mock_post:
+            with patch.object(
+                broker,
+                "_load_dual_listing_metrics",
+                new=AsyncMock(return_value=(True, 0.004, 0.002, 100000.0, 90000.0)),
+            ):
+                await broker.send_order("005930", "BUY", 1, price=50000, session_id="KRX_REG")
+
+        order_call = mock_post.call_args_list[1]
+        body = order_call[1].get("json", {})
+        assert body["EXCG_ID_DVSN_CD"] == "NXT"
+
 
 # ---------------------------------------------------------------------------
 # TR_ID live/paper branching (issues #201, #202, #203)

tests/test_kr_exchange_router.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from src.broker.kr_exchange_router import KRExchangeRouter
+
+
+def test_ranking_market_code_by_session() -> None:
+    router = KRExchangeRouter()
+    assert router.resolve_for_ranking("KRX_REG") == "J"
+    assert router.resolve_for_ranking("NXT_PRE") == "NX"
+    assert router.resolve_for_ranking("NXT_AFTER") == "NX"
+
+
+def test_order_exchange_falls_back_to_session_default_on_missing_data() -> None:
+    router = KRExchangeRouter()
+    resolved = router.resolve_for_order(
+        stock_code="0001A0",
+        session_id="NXT_PRE",
+        is_dual_listed=True,
+        spread_krx=None,
+        spread_nxt=None,
+        liquidity_krx=None,
+        liquidity_nxt=None,
+    )
+    assert resolved.exchange_code == "NXT"
+    assert resolved.reason == "fallback_data_unavailable"
+
+
+def test_order_exchange_uses_spread_preference_for_dual_listing() -> None:
+    router = KRExchangeRouter()
+    resolved = router.resolve_for_order(
+        stock_code="0001A0",
+        session_id="KRX_REG",
+        is_dual_listed=True,
+        spread_krx=0.005,
+        spread_nxt=0.003,
+        liquidity_krx=100000.0,
+        liquidity_nxt=90000.0,
+    )
+    assert resolved.exchange_code == "NXT"
+    assert resolved.reason == "dual_listing_spread"

tests/test_main.py

@@ -34,7 +34,6 @@ from src.main import (
     _extract_held_codes_from_balance,
     _extract_held_qty_from_balance,
     _handle_market_close,
-    _has_market_session_transition,
     _inject_staged_exit_features,
     _maybe_queue_order_intent,
     _resolve_market_setting,
@@ -44,7 +43,6 @@ from src.main import (
     _run_evolution_loop,
     _should_block_overseas_buy_for_fx_buffer,
     _should_force_exit_for_overnight,
-    _should_rescan_market,
     _split_trade_pnl_components,
     _start_dashboard_server,
     _stoploss_cooldown_minutes,
@@ -142,38 +140,6 @@ class TestExtractAvgPriceFromBalance:
         result = _extract_avg_price_from_balance(balance, "AAPL", is_domestic=False)
         assert result == 170.5
 
-
-class TestRealtimeSessionStateHelpers:
-    """Tests for realtime loop session-transition/rescan helper logic."""
-
-    def test_has_market_session_transition_when_state_missing(self) -> None:
-        states: dict[str, str] = {}
-        assert _has_market_session_transition(states, "US_NASDAQ", "US_REG")
-
-    def test_has_market_session_transition_when_session_changes(self) -> None:
-        states = {"US_NASDAQ": "US_PRE"}
-        assert _has_market_session_transition(states, "US_NASDAQ", "US_REG")
-
-    def test_has_market_session_transition_false_when_same_session(self) -> None:
-        states = {"US_NASDAQ": "US_REG"}
-        assert not _has_market_session_transition(states, "US_NASDAQ", "US_REG")
-
-    def test_should_rescan_market_forces_on_session_transition(self) -> None:
-        assert _should_rescan_market(
-            last_scan=1000.0,
-            now_timestamp=1050.0,
-            rescan_interval=300.0,
-            session_changed=True,
-        )
-
-    def test_should_rescan_market_uses_interval_without_transition(self) -> None:
-        assert not _should_rescan_market(
-            last_scan=1000.0,
-            now_timestamp=1050.0,
-            rescan_interval=300.0,
-            session_changed=False,
-        )
-
     def test_returns_zero_when_field_absent(self) -> None:
         """Returns 0.0 when pchs_avg_pric key is missing entirely."""
         balance = {"output1": [{"pdno": "005930", "ord_psbl_qty": "5"}]}
@@ -947,46 +913,6 @@ class TestTradingCycleTelegramIntegration:
         # Verify notification was attempted
         mock_telegram.notify_trade_execution.assert_called_once()
 
-    @pytest.mark.asyncio
-    async def test_kr_rejected_order_does_not_notify_or_log_trade(
-        self,
-        mock_broker: MagicMock,
-        mock_overseas_broker: MagicMock,
-        mock_scenario_engine: MagicMock,
-        mock_playbook: DayPlaybook,
-        mock_risk: MagicMock,
-        mock_db: MagicMock,
-        mock_decision_logger: MagicMock,
-        mock_context_store: MagicMock,
-        mock_criticality_assessor: MagicMock,
-        mock_telegram: MagicMock,
-        mock_market: MagicMock,
-    ) -> None:
-        """KR orders rejected by KIS should not trigger success side effects."""
-        mock_broker.send_order = AsyncMock(
-            return_value={"rt_cd": "1", "msg1": "장운영시간이 아닙니다."}
-        )
-
-        with patch("src.main.log_trade") as mock_log_trade:
-            await trading_cycle(
-                broker=mock_broker,
-                overseas_broker=mock_overseas_broker,
-                scenario_engine=mock_scenario_engine,
-                playbook=mock_playbook,
-                risk=mock_risk,
-                db_conn=mock_db,
-                decision_logger=mock_decision_logger,
-                context_store=mock_context_store,
-                criticality_assessor=mock_criticality_assessor,
-                telegram=mock_telegram,
-                market=mock_market,
-                stock_code="005930",
-                scan_candidates={},
-            )
-
-        mock_telegram.notify_trade_execution.assert_not_called()
-        mock_log_trade.assert_not_called()
-
     @pytest.mark.asyncio
     async def test_fat_finger_notification_sent(
         self,

tests/test_market_schedule.py

@@ -165,17 +165,6 @@ class TestGetOpenMarkets:
         )
         assert {m.code for m in extended} == {"US_NASDAQ", "US_NYSE", "US_AMEX"}
 
-    def test_get_open_markets_excludes_us_day_when_extended_enabled(self) -> None:
-        """US_DAY should be treated as non-tradable even in extended-session lookup."""
-        # Monday 2026-02-02 10:30 KST = 01:30 UTC (US_DAY by session classification)
-        test_time = datetime(2026, 2, 2, 1, 30, tzinfo=ZoneInfo("UTC"))
-        extended = get_open_markets(
-            enabled_markets=["US_NASDAQ", "US_NYSE", "US_AMEX"],
-            now=test_time,
-            include_extended_sessions=True,
-        )
-        assert extended == []
-
 
 class TestGetNextMarketOpen:
     """Test get_next_market_open function."""
@@ -225,8 +214,8 @@ class TestGetNextMarketOpen:
     def test_get_next_market_open_prefers_extended_session(self) -> None:
         """Extended lookup should return premarket open time before regular open."""
         # Monday 2026-02-02 07:00 EST = 12:00 UTC
-        # US_DAY is treated as non-tradable in extended lookup, so after entering
+        # By v3 KST session rules, US is OFF only in KST 07:00-10:00 (UTC 22:00-01:00).
-        # US_DAY the next tradable OFF->ON transition is US_PRE at 09:00 UTC next day.
+        # At 12:00 UTC market is active, so next OFF->ON transition is 01:00 UTC next day.
         test_time = datetime(2026, 2, 2, 12, 0, tzinfo=ZoneInfo("UTC"))
         market, next_open = get_next_market_open(
             enabled_markets=["US_NASDAQ"],
@@ -234,7 +223,7 @@ class TestGetNextMarketOpen:
             include_extended_sessions=True,
         )
         assert market.code == "US_NASDAQ"
-        assert next_open == datetime(2026, 2, 3, 9, 0, tzinfo=ZoneInfo("UTC"))
+        assert next_open == datetime(2026, 2, 3, 1, 0, tzinfo=ZoneInfo("UTC"))
 
 
 class TestExpandMarketCodes:

tests/test_smart_scanner.py

@@ -103,6 +103,33 @@ class TestSmartVolatilityScanner:
         assert candidates[0].stock_code == "005930"
         assert candidates[0].signal == "oversold"
 
+    @pytest.mark.asyncio
+    async def test_scan_domestic_passes_session_id_to_rankings(
+        self, scanner: SmartVolatilityScanner, mock_broker: MagicMock
+    ) -> None:
+        fluctuation_rows = [
+            {
+                "stock_code": "005930",
+                "name": "Samsung",
+                "price": 70000,
+                "volume": 5000000,
+                "change_rate": 1.0,
+                "volume_increase_rate": 120,
+            },
+        ]
+        mock_broker.fetch_market_rankings.side_effect = [fluctuation_rows, fluctuation_rows]
+        mock_broker.get_daily_prices.return_value = [
+            {"open": 1, "high": 71000, "low": 69000, "close": 70000, "volume": 1000000},
+            {"open": 1, "high": 70000, "low": 68000, "close": 69000, "volume": 900000},
+        ]
+
+        await scanner.scan(domestic_session_id="NXT_PRE")
+
+        first_call = mock_broker.fetch_market_rankings.call_args_list[0]
+        second_call = mock_broker.fetch_market_rankings.call_args_list[1]
+        assert first_call.kwargs["session_id"] == "NXT_PRE"
+        assert second_call.kwargs["session_id"] == "NXT_PRE"
+
     @pytest.mark.asyncio
     async def test_scan_domestic_finds_momentum_candidate(
         self, scanner: SmartVolatilityScanner, mock_broker: MagicMock

workflow/session-handover.md

@@ -137,3 +137,11 @@
 - next_ticket: #377
 - process_gate_checked: process_ticket=#306,#308 merged_to_feature_branch=yes
 - risks_or_notes: refresh 단계를 최대 3회(초기+재시도2), 실패 시 지수 백오프로 재시도하고 성공 시 즉시 중단, 소진 시 오류를 기록한 뒤 다음 단계를 계속 수행한다.
+
+### 2026-03-04 | session=codex-issue409-start
+- branch: feature/issue-409-kr-session-exchange-routing
+- docs_checked: docs/workflow.md, docs/commands.md, docs/agent-constraints.md
+- open_issues_reviewed: #409, #318, #325
+- next_ticket: #409
+- process_gate_checked: process_ticket=#306,#308 merged_to_feature_branch=yes
+- risks_or_notes: #409 코드수정/검증 후 프로그램 재시작 및 24h 런타임 모니터링 수행, 모니터 이상 징후는 별도 이슈 발행