fix: backfill split pnl migration and harden partial pnl inputs

src/db.py

@@ -60,6 +60,16 @@ def init_db(db_path: str) -> sqlite3.Connection:
         conn.execute("ALTER TABLE trades ADD COLUMN strategy_pnl REAL DEFAULT 0.0")
     if "fx_pnl" not in columns:
         conn.execute("ALTER TABLE trades ADD COLUMN fx_pnl REAL DEFAULT 0.0")
+    # Backfill legacy rows where only pnl existed before split accounting columns.
+    conn.execute(
+        """
+        UPDATE trades
+        SET strategy_pnl = pnl, fx_pnl = 0.0
+        WHERE pnl != 0.0
+          AND strategy_pnl = 0.0
+          AND fx_pnl = 0.0
+        """
+    )
 
     # Context tree tables for multi-layered memory management
     conn.execute(
@@ -211,9 +221,9 @@ def log_trade(
         strategy_pnl = pnl
         fx_pnl = 0.0
     elif strategy_pnl is None:
-        strategy_pnl = pnl - float(fx_pnl or 0.0)
+        strategy_pnl = pnl - float(fx_pnl or 0.0) if pnl != 0.0 else 0.0
     elif fx_pnl is None:
-        fx_pnl = pnl - float(strategy_pnl)
+        fx_pnl = pnl - float(strategy_pnl) if pnl != 0.0 else 0.0
     if pnl == 0.0 and (strategy_pnl or fx_pnl):
         pnl = float(strategy_pnl) + float(fx_pnl)
 

tests/test_db.py

@@ -184,6 +184,13 @@ def test_mode_migration_adds_column_to_existing_db() -> None:
                 decision_id TEXT
             )"""
         )
+        old_conn.execute(
+            """
+            INSERT INTO trades (
+                timestamp, stock_code, action, confidence, rationale, quantity, price, pnl
+            ) VALUES ('2026-01-01T00:00:00+00:00', 'AAPL', 'SELL', 90, 'legacy', 1, 100.0, 123.45)
+            """
+        )
         old_conn.commit()
         old_conn.close()
 
@@ -194,6 +201,13 @@ def test_mode_migration_adds_column_to_existing_db() -> None:
         assert "mode" in columns
         assert "strategy_pnl" in columns
         assert "fx_pnl" in columns
+        migrated = conn.execute(
+            "SELECT pnl, strategy_pnl, fx_pnl FROM trades WHERE stock_code='AAPL' LIMIT 1"
+        ).fetchone()
+        assert migrated is not None
+        assert migrated[0] == 123.45
+        assert migrated[1] == 123.45
+        assert migrated[2] == 0.0
         conn.close()
     finally:
         os.unlink(db_path)
@@ -241,3 +255,25 @@ def test_log_trade_backward_compat_sets_strategy_pnl_from_pnl() -> None:
     assert row[0] == 50.0
     assert row[1] == 50.0
     assert row[2] == 0.0
+
+
+def test_log_trade_partial_fx_input_does_not_infer_negative_strategy_pnl() -> None:
+    conn = init_db(":memory:")
+    log_trade(
+        conn=conn,
+        stock_code="AAPL",
+        action="SELL",
+        confidence=70,
+        rationale="fx only",
+        pnl=0.0,
+        fx_pnl=10.0,
+        market="US_NASDAQ",
+        exchange_code="NASD",
+    )
+    row = conn.execute(
+        "SELECT pnl, strategy_pnl, fx_pnl FROM trades ORDER BY id DESC LIMIT 1"
+    ).fetchone()
+    assert row is not None
+    assert row[0] == 10.0
+    assert row[1] == 0.0
+    assert row[2] == 10.0