fix: include exchange_code in latest BUY matching key (#323)

src/db.py

@@ -290,22 +290,47 @@ def _resolve_session_id(*, market: str, session_id: str | None) -> str:
 
 
 def get_latest_buy_trade(
-    conn: sqlite3.Connection, stock_code: str, market: str
+    conn: sqlite3.Connection,
+    stock_code: str,
+    market: str,
+    exchange_code: str | None = None,
 ) -> dict[str, Any] | None:
     """Fetch the most recent BUY trade for a stock and market."""
-    cursor = conn.execute(
-        """
-        SELECT decision_id, price, quantity
-        FROM trades
-        WHERE stock_code = ?
-          AND market = ?
-          AND action = 'BUY'
-          AND decision_id IS NOT NULL
-        ORDER BY timestamp DESC
-        LIMIT 1
-        """,
-        (stock_code, market),
-    )
+    if exchange_code:
+        cursor = conn.execute(
+            """
+            SELECT decision_id, price, quantity
+            FROM trades
+            WHERE stock_code = ?
+              AND market = ?
+              AND action = 'BUY'
+              AND decision_id IS NOT NULL
+              AND (
+                  exchange_code = ?
+                  OR exchange_code IS NULL
+                  OR exchange_code = ''
+              )
+            ORDER BY
+              CASE WHEN exchange_code = ? THEN 0 ELSE 1 END,
+              timestamp DESC
+            LIMIT 1
+            """,
+            (stock_code, market, exchange_code, exchange_code),
+        )
+    else:
+        cursor = conn.execute(
+            """
+            SELECT decision_id, price, quantity
+            FROM trades
+            WHERE stock_code = ?
+              AND market = ?
+              AND action = 'BUY'
+              AND decision_id IS NOT NULL
+            ORDER BY timestamp DESC
+            LIMIT 1
+            """,
+            (stock_code, market),
+        )
     row = cursor.fetchone()
     if not row:
         return None

src/main.py

@@ -1655,7 +1655,12 @@ async def trading_cycle(
                 logger.warning("Telegram notification failed: %s", exc)
 
         if decision.action == "SELL" and order_succeeded:
-            buy_trade = get_latest_buy_trade(db_conn, stock_code, market.code)
+            buy_trade = get_latest_buy_trade(
+                db_conn,
+                stock_code,
+                market.code,
+                exchange_code=market.exchange_code,
+            )
             if buy_trade and buy_trade.get("price") is not None:
                 buy_price = float(buy_trade["price"])
                 buy_qty = int(buy_trade.get("quantity") or 1)
@@ -2752,7 +2757,12 @@ async def run_daily_session(
                     continue
 
                 if decision.action == "SELL" and order_succeeded:
-                    buy_trade = get_latest_buy_trade(db_conn, stock_code, market.code)
+                    buy_trade = get_latest_buy_trade(
+                        db_conn,
+                        stock_code,
+                        market.code,
+                        exchange_code=market.exchange_code,
+                    )
                     if buy_trade and buy_trade.get("price") is not None:
                         buy_price = float(buy_trade["price"])
                         buy_qty = int(buy_trade.get("quantity") or 1)

tests/test_db.py

@@ -3,7 +3,7 @@
 import tempfile
 import os
 
-from src.db import get_open_position, init_db, log_trade
+from src.db import get_latest_buy_trade, get_open_position, init_db, log_trade
 
 
 def test_get_open_position_returns_latest_buy() -> None:
@@ -329,3 +329,39 @@ def test_log_trade_unknown_market_falls_back_to_unknown_session() -> None:
     row = conn.execute("SELECT session_id FROM trades ORDER BY id DESC LIMIT 1").fetchone()
     assert row is not None
     assert row[0] == "UNKNOWN"
+
+
+def test_get_latest_buy_trade_prefers_exchange_code_match() -> None:
+    conn = init_db(":memory:")
+    log_trade(
+        conn=conn,
+        stock_code="AAPL",
+        action="BUY",
+        confidence=80,
+        rationale="legacy",
+        quantity=10,
+        price=120.0,
+        market="US_NASDAQ",
+        exchange_code="",
+        decision_id="legacy-buy",
+    )
+    log_trade(
+        conn=conn,
+        stock_code="AAPL",
+        action="BUY",
+        confidence=85,
+        rationale="matched",
+        quantity=5,
+        price=125.0,
+        market="US_NASDAQ",
+        exchange_code="NASD",
+        decision_id="matched-buy",
+    )
+    matched = get_latest_buy_trade(
+        conn,
+        stock_code="AAPL",
+        market="US_NASDAQ",
+        exchange_code="NASD",
+    )
+    assert matched is not None
+    assert matched["decision_id"] == "matched-buy"