fix: use symbol_side as peakPnLCache key to support dual-side positions (#657)

Fixes #652
Previously, peakPnLCache used only 'symbol' as the key, causing LONG
and SHORT positions of the same symbol to share the same peak P&L value.
This led to incorrect drawdown calculations and emergency close triggers.
Changes:
- checkPositionDrawdown: use posKey (symbol_side) for cache access
- UpdatePeakPnL: add side parameter and use posKey internally
- ClearPeakPnLCache: add side parameter and use posKey internally
Example fix:
- Before: peakPnLCache["BTCUSDT"] shared by both LONG and SHORT
- After: peakPnLCache["BTCUSDT_long"] and peakPnLCache["BTCUSDT_short"]
Impact:
- Fixes incorrect drawdown monitoring for dual positions
- Prevents false emergency close triggers on profitable positions

trader/auto_trader.go

@@ -1553,18 +1553,21 @@ func (at *AutoTrader) checkPositionDrawdown() {
 			currentPnLPct = ((entryPrice - markPrice) / entryPrice) * float64(leverage) * 100
 		}
 
+		// 构造持仓唯一标识（区分多空）
+		posKey := symbol + "_" + side
+
 		// 获取该持仓的历史最高收益
 		at.peakPnLCacheMutex.RLock()
-		peakPnLPct, exists := at.peakPnLCache[symbol]
+		peakPnLPct, exists := at.peakPnLCache[posKey]
 		at.peakPnLCacheMutex.RUnlock()
 
 		if !exists {
 			// 如果没有历史最高记录，使用当前盈亏作为初始值
 			peakPnLPct = currentPnLPct
-			at.UpdatePeakPnL(symbol, currentPnLPct)
+			at.UpdatePeakPnL(symbol, side, currentPnLPct)
 		} else {
 			// 更新峰值缓存
-			at.UpdatePeakPnL(symbol, currentPnLPct)
+			at.UpdatePeakPnL(symbol, side, currentPnLPct)
 		}
 
 		// 计算回撤（从最高点下跌的幅度）
@@ -1583,8 +1586,8 @@ func (at *AutoTrader) checkPositionDrawdown() {
 				log.Printf("❌ 回撤平仓失败 (%s %s): %v", symbol, side, err)
 			} else {
 				log.Printf("✅ 回撤平仓成功: %s %s", symbol, side)
-				// 平仓后清理该symbol的缓存
-				at.ClearPeakPnLCache(symbol)
+				// 平仓后清理该持仓的缓存
+				at.ClearPeakPnLCache(symbol, side)
 			}
 		} else if currentPnLPct > 5.0 {
 			// 记录接近平仓条件的情况（用于调试）
@@ -1630,25 +1633,27 @@ func (at *AutoTrader) GetPeakPnLCache() map[string]float64 {
 }
 
 // UpdatePeakPnL 更新最高收益缓存
-func (at *AutoTrader) UpdatePeakPnL(symbol string, currentPnLPct float64) {
+func (at *AutoTrader) UpdatePeakPnL(symbol, side string, currentPnLPct float64) {
 	at.peakPnLCacheMutex.Lock()
 	defer at.peakPnLCacheMutex.Unlock()
 
-	if peak, exists := at.peakPnLCache[symbol]; exists {
+	posKey := symbol + "_" + side
+	if peak, exists := at.peakPnLCache[posKey]; exists {
 		// 更新峰值（如果是多头，取较大值；如果是空头，currentPnLPct为负，也要比较）
 		if currentPnLPct > peak {
-			at.peakPnLCache[symbol] = currentPnLPct
+			at.peakPnLCache[posKey] = currentPnLPct
 		}
 	} else {
 		// 首次记录
-		at.peakPnLCache[symbol] = currentPnLPct
+		at.peakPnLCache[posKey] = currentPnLPct
 	}
 }
 
-// ClearPeakPnLCache 清除指定symbol的峰值缓存
-func (at *AutoTrader) ClearPeakPnLCache(symbol string) {
+// ClearPeakPnLCache 清除指定持仓的峰值缓存
+func (at *AutoTrader) ClearPeakPnLCache(symbol, side string) {
 	at.peakPnLCacheMutex.Lock()
 	defer at.peakPnLCacheMutex.Unlock()
 
-	delete(at.peakPnLCache, symbol)
+	posKey := symbol + "_" + side
+	delete(at.peakPnLCache, posKey)
 }