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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.
+