fix: 重启后总PnL回到0的问题 + 前端PnL图表公式统一

- trader.go: NewTrader 启动时从DB GetAllClosedTrades() 加载所有已平仓交易到 closedTrades
- trader.go: 新增 safeFloat/safeStr 辅助函数处理DB空指针
- db/trade_repo.go: 新增 GetAllClosedTrades() 方法
- frontend: PnL图表标题和曲线改用 2*AmountUSD*NetPnl/100 公式，与后端Stats一致

db/trade_repo.go

@@ -260,6 +260,20 @@ func (d *DB) GetScalePrices(tradeID int64) (longPrices, shortPrices []float64, e
 	return longPrices, shortPrices, rows.Err()
 }
 
+// GetAllClosedTrades returns all closed trades for PnL history restoration.
+func (d *DB) GetAllClosedTrades() ([]TradeRecord, error) {
+	rows, err := d.Query(`SELECT id, coin, direction, status, entry_spread, exit_spread,
+		long_exchange, short_exchange, long_entry, long_exit, short_entry, short_exit,
+		long_pnl, short_pnl, fee_entry, fee_exit, net_pnl,
+		amount_usd, scale_count, exit_reason, convergence, opened_at, closed_at
+		FROM trades WHERE status='closed' ORDER BY id`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	return scanTrades(rows)
+}
+
 // GetClosedStats returns convergence counts from the database.
 func (d *DB) GetClosedStats() (converged, diverged, flat, total int, err error) {
 	if err = d.QueryRow("SELECT COUNT(*) FROM trades WHERE status='closed'").Scan(&total); err != nil {

frontend/src/App.jsx

@@ -562,7 +562,7 @@ function PnlChart() {
           .filter(t => t.ClosedAt && t.NetPnl != null)
           .sort((a, b) => new Date(a.ClosedAt) - new Date(b.ClosedAt))
         setData(trades)
-        const total = trades.reduce((sum, t) => sum + (t.NetPnl || 0), 0)
+        const total = trades.reduce((sum, t) => sum + 2 * (t.AmountUSD || 0) * (t.NetPnl || 0) / 100, 0)
         setTotalPnl(total)
       } catch (e) {}
     }
@@ -596,7 +596,7 @@ function PnlChart() {
     const points = []
     let cum = 0
     for (const t of data) {
-      cum += (t.AmountUSD || 0) * (t.NetPnl || 0) / 100
+      cum += 2 * (t.AmountUSD || 0) * (t.NetPnl || 0) / 100
       points.push({ x: new Date(t.ClosedAt).getTime(), y: cum })
     }
 

trader.go

@@ -183,6 +183,35 @@ func NewTrader(cfg *Config, database *db.DB) *Trader {
 	// Restore open positions from DB on restart
 	if database != nil {
 		t.restoreOpenPositions()
+
+		// Load historical closed trades for PnL stats (so total PnL survives restart)
+		if closed, err := database.GetAllClosedTrades(); err == nil {
+			for i := range closed {
+				dbTr := &closed[i]
+				pnlPct := safeFloat(dbTr.NetPnl)
+				pnlUSD := 2 * dbTr.AmountUSD * pnlPct / 100
+				closedAt := time.Time{}
+				if dbTr.ClosedAt != nil {
+					closedAt = *dbTr.ClosedAt
+				}
+				record := TradeRecord{
+					Coin:        dbTr.Coin,
+					Direction:   dbTr.Direction,
+					EntrySpread: safeFloat(dbTr.EntrySpread),
+					ExitSpread:  safeFloat(dbTr.ExitSpread),
+					PnlPct:      pnlPct,
+					PnlUSD:      pnlUSD,
+					Convergence: safeStr(dbTr.Convergence),
+					Reason:      safeStr(dbTr.ExitReason),
+					Duration:    closedAt.Sub(dbTr.OpenedAt).Round(time.Second).String(),
+					OpenedAt:    dbTr.OpenedAt,
+					ClosedAt:    closedAt,
+					ScaleLevels: dbTr.ScaleCount,
+					AmountUSD:   dbTr.AmountUSD,
+				}
+				t.closedTrades = append(t.closedTrades, record)
+			}
+		}
 		// Load historical closed trade stats for convergence display
 		if c, d, f, tot, err := database.GetClosedStats(); err == nil {
 			t.dbConverged, t.dbDiverged, t.dbFlat, t.dbTotal = c, d, f, tot
@@ -1282,4 +1311,20 @@ func (t *Trader) RemoveBlacklist(coin string) {
 	defer t.mu.Unlock()
 	delete(t.blacklist, coin)
 	log.Printf("[Trader] ✅ %s: Removed from blacklist", coin)
+}
+
+// safeFloat returns 0 for nil float64 pointers (DB nullable fields).
+func safeFloat(f *float64) float64 {
+	if f == nil {
+		return 0
+	}
+	return *f
+}
+
+// safeStr returns empty string for nil string pointers (DB nullable fields).
+func safeStr(s *string) string {
+	if s == nil {
+		return ""
+	}
+	return *s
 }