fix(decision): 添加槓桿超限 fallback 機制並澄清盈虧計算說明 (#716)

* fix(decision): 添加槓桿超限 fallback 機制並澄清盈虧計算說明

1. AI 決策輸出超限槓桿時（如 20x），驗證直接拒絕導致整個交易週期失敗
2. Prompt 未明確說明盈虧百分比已包含槓桿效應，導致 AI 思維鏈中誤用價格變動%

- **Before**: 超限直接報錯 → 決策失敗
- **After**: 自動降級為配置上限 → 決策繼續執行
- **效果**: SOLUSDT 20x → 自動修正為 5x（配置上限）

- 明確告知 AI：系統提供的「盈虧%」已包含槓桿效應
- 公式: 盈虧% = (未實現盈虧 / 保證金) × 100
- 示例: 5x 槓桿，價格漲 2% = 實際盈利 10%

- 測試山寨幣超限修正（20x → 5x）
- 測試 BTC/ETH 超限修正（20x → 10x）
- 測試正常範圍不修正
- 測試無效槓桿拒絕

```
PASS: TestLeverageFallback/山寨币杠杆超限_自动修正为上限
PASS: TestLeverageFallback/BTC杠杆超限_自动修正为上限
PASS: TestLeverageFallback/杠杆在上限内_不修正
PASS: TestLeverageFallback/杠杆为0_应该报错
```

- ✅ 向後兼容：正常槓桿範圍不受影響
- ✅ 容錯性增強：AI 輸出超限時系統自動修正
- ✅ 決策質量提升：AI 對槓桿收益有正確認知

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

* style: apply go fmt after rebase

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

---------

Co-authored-by: ZhouYongyou <128128010+zhouyongyou@users.noreply.github.com>
Co-authored-by: tinkle-community <tinklefund@gmail.com>

decision/engine.go

@@ -731,8 +731,14 @@ func validateDecision(d *Decision, accountEquity float64, btcEthLeverage, altcoi
 			maxPositionValue = accountEquity * 10 // BTC/ETH最多10倍账户净值
 		}
 
-		if d.Leverage <= 0 || d.Leverage > maxLeverage {
-			return fmt.Errorf("杠杆必须在1-%d之间（%s，当前配置上限%d倍）: %d", maxLeverage, d.Symbol, maxLeverage, d.Leverage)
+		// ✅ Fallback 机制：杠杆超限时自动修正为上限值（而不是直接拒绝决策）
+		if d.Leverage <= 0 {
+			return fmt.Errorf("杠杆必须大于0: %d", d.Leverage)
+		}
+		if d.Leverage > maxLeverage {
+			log.Printf("⚠️  [Leverage Fallback] %s 杠杆超限 (%dx > %dx)，自动调整为上限值 %dx",
+				d.Symbol, d.Leverage, maxLeverage, maxLeverage)
+			d.Leverage = maxLeverage // 自动修正为上限值
 		}
 		if d.PositionSizeUSD <= 0 {
 			return fmt.Errorf("仓位大小必须大于0: %.2f", d.PositionSizeUSD)

decision/validate_test.go

@@ -0,0 +1,100 @@
+package decision
+
+import (
+	"testing"
+)
+
+// TestLeverageFallback 测试杠杆超限时的自动修正功能
+func TestLeverageFallback(t *testing.T) {
+	tests := []struct {
+		name            string
+		decision        Decision
+		accountEquity   float64
+		btcEthLeverage  int
+		altcoinLeverage int
+		wantLeverage    int // 期望修正后的杠杆值
+		wantError       bool
+	}{
+		{
+			name: "山寨币杠杆超限_自动修正为上限",
+			decision: Decision{
+				Symbol:          "SOLUSDT",
+				Action:          "open_long",
+				Leverage:        20, // 超过上限
+				PositionSizeUSD: 100,
+				StopLoss:        50,
+				TakeProfit:      200,
+			},
+			accountEquity:   100,
+			btcEthLeverage:  10,
+			altcoinLeverage: 5, // 上限 5x
+			wantLeverage:    5, // 应该修正为 5
+			wantError:       false,
+		},
+		{
+			name: "BTC杠杆超限_自动修正为上限",
+			decision: Decision{
+				Symbol:          "BTCUSDT",
+				Action:          "open_long",
+				Leverage:        20, // 超过上限
+				PositionSizeUSD: 1000,
+				StopLoss:        90000,
+				TakeProfit:      110000,
+			},
+			accountEquity:   100,
+			btcEthLeverage:  10, // 上限 10x
+			altcoinLeverage: 5,
+			wantLeverage:    10, // 应该修正为 10
+			wantError:       false,
+		},
+		{
+			name: "杠杆在上限内_不修正",
+			decision: Decision{
+				Symbol:          "ETHUSDT",
+				Action:          "open_short",
+				Leverage:        5, // 未超限
+				PositionSizeUSD: 500,
+				StopLoss:        4000,
+				TakeProfit:      3000,
+			},
+			accountEquity:   100,
+			btcEthLeverage:  10,
+			altcoinLeverage: 5,
+			wantLeverage:    5, // 保持不变
+			wantError:       false,
+		},
+		{
+			name: "杠杆为0_应该报错",
+			decision: Decision{
+				Symbol:          "SOLUSDT",
+				Action:          "open_long",
+				Leverage:        0, // 无效
+				PositionSizeUSD: 100,
+				StopLoss:        50,
+				TakeProfit:      200,
+			},
+			accountEquity:   100,
+			btcEthLeverage:  10,
+			altcoinLeverage: 5,
+			wantLeverage:    0,
+			wantError:       true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := validateDecision(&tt.decision, tt.accountEquity, tt.btcEthLeverage, tt.altcoinLeverage)
+
+			// 检查错误状态
+			if (err != nil) != tt.wantError {
+				t.Errorf("validateDecision() error = %v, wantError %v", err, tt.wantError)
+				return
+			}
+
+			// 如果不应该报错，检查杠杆是否被正确修正
+			if !tt.wantError && tt.decision.Leverage != tt.wantLeverage {
+				t.Errorf("Leverage not corrected: got %d, want %d", tt.decision.Leverage, tt.wantLeverage)
+			}
+		})
+	}
+}

manager/trader_manager.go

@@ -850,6 +850,7 @@ func (tm *TraderManager) LoadUserTraders(database *config.Database, userID strin
 //   - database: 数据库实例
 //   - userID: 用户ID
 //   - traderID: 交易员ID
+//
 // 返回:
 //   - error: 如果交易员不存在、配置无效或加载失败则返回错误
 func (tm *TraderManager) LoadTraderByID(database *config.Database, userID, traderID string) error {