修复(#86): 排除永久订阅回归促销误判

Co-authored-by: multica-agent <github@multica.ai>

initialize/migrate/database/02154_promo_system.up.sql

@@ -11,19 +11,19 @@ CREATE TABLE IF NOT EXISTS `promo_rule` (
   `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   `deleted_at` DATETIME DEFAULT NULL COMMENT '软删除时间',
   PRIMARY KEY (`id`),
-  KEY `idx_enabled_priority` (`enabled`, `priority` DESC),
-  KEY `idx_deleted_at` (`deleted_at`)
+  KEY `idx_enabled_priority_deleted` (`enabled`, `deleted_at`, `priority` DESC)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='促销规则表';
 
 CREATE TABLE IF NOT EXISTS `subscribe_promo` (
   `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
   `subscribe_id` BIGINT UNSIGNED NOT NULL COMMENT '套餐规格 ID',
+  `quantity` INT NOT NULL DEFAULT 0 COMMENT '购买数量',
   `promo_rule_id` BIGINT UNSIGNED NOT NULL COMMENT '促销规则 ID',
   `promo_price` BIGINT NOT NULL DEFAULT 0 COMMENT '该规格在此规则下的优惠价（分）',
   `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
   `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   PRIMARY KEY (`id`),
-  UNIQUE KEY `uk_subscribe_rule` (`subscribe_id`, `promo_rule_id`),
+  UNIQUE KEY `uk_subscribe_qty_rule` (`subscribe_id`, `quantity`, `promo_rule_id`),
   KEY `idx_promo_rule_id` (`promo_rule_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='规格促销价表';
 

internal/logic/common/promoEligibility.go

@@ -11,6 +11,7 @@ import (
 	"github.com/perfect-panel/server/pkg/xerr"
 	"github.com/pkg/errors"
 	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
 )
 
 type PromoResult struct {
@@ -148,6 +149,12 @@ func evaluateInactiveUserPromo(
 	err := db.WithContext(ctx).
 		Model(&user.Subscribe{}).
 		Where("user_id = ?", userID).
+		Order(clause.OrderBy{
+			Expression: clause.Expr{
+				SQL:  "CASE WHEN expire_time = ? THEN 0 ELSE 1 END",
+				Vars: []interface{}{permanentSubscribeExpireTime()},
+			},
+		}).
 		Order("expire_time DESC").
 		Limit(1).
 		Take(&lastSub).Error
@@ -158,8 +165,19 @@ func evaluateInactiveUserPromo(
 		return false, time.Time{}, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "query promo inactive user subscription failed")
 	}
 
-	threshold := now.AddDate(0, -params.InactiveMonths, 0)
-	return lastSub.ExpireTime.Before(threshold) || lastSub.ExpireTime.Equal(threshold), ruleExpiresAt, nil
+	return isInactivePromoEligible(lastSub.ExpireTime, now, params.InactiveMonths), ruleExpiresAt, nil
+}
+
+func isInactivePromoEligible(expireTime time.Time, now time.Time, inactiveMonths int) bool {
+	if expireTime.Equal(permanentSubscribeExpireTime()) {
+		return false
+	}
+	threshold := now.AddDate(0, -inactiveMonths, 0)
+	return expireTime.Before(threshold) || expireTime.Equal(threshold)
+}
+
+func permanentSubscribeExpireTime() time.Time {
+	return time.UnixMilli(0)
 }
 
 func promoRuleExpiresAt(rule *promo.RuleWithPrice) time.Time {

internal/logic/common/promoEligibility_test.go

@@ -0,0 +1,51 @@
+package common
+
+import (
+	"testing"
+	"time"
+)
+
+func TestIsInactivePromoEligible(t *testing.T) {
+	now := time.Date(2026, time.May, 27, 12, 0, 0, 0, time.UTC)
+
+	tests := []struct {
+		name     string
+		expireAt time.Time
+		want     bool
+	}{
+		{
+			name:     "expired before inactive threshold is eligible",
+			expireAt: now.AddDate(0, -4, 0),
+			want:     true,
+		},
+		{
+			name:     "expired exactly at inactive threshold is eligible",
+			expireAt: now.AddDate(0, -3, 0),
+			want:     true,
+		},
+		{
+			name:     "recently expired subscription is not eligible",
+			expireAt: now.AddDate(0, -2, 0),
+			want:     false,
+		},
+		{
+			name:     "active future subscription is not eligible",
+			expireAt: now.Add(time.Hour),
+			want:     false,
+		},
+		{
+			name:     "permanent subscription marker is not eligible",
+			expireAt: time.UnixMilli(0),
+			want:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := isInactivePromoEligible(tt.expireAt, now, 3)
+			if got != tt.want {
+				t.Fatalf("isInactivePromoEligible() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}