feat(pay-v2): P8 Task1 Subscription 模型 + 三态状态机 + store

internal/model/testdb.go

@@ -32,7 +32,7 @@ func OpenTestDB(t *testing.T) *gorm.DB {
 		t.Fatalf("open test db: %v", err)
 	}
 	if err := db.AutoMigrate(&OrderV2{}, &Attempt{}, &Account{}, &Refund{}, &WebhookDelivery{},
-		&Product{}, &ProductPrice{}); err != nil {
+		&Product{}, &ProductPrice{}, &Subscription{}); err != nil {
 		t.Fatalf("migrate: %v", err)
 	}
 	if err := UpgradeWebhookDeliveryIndex(db); err != nil {

internal/model/v2.go

@@ -121,3 +121,33 @@ type Refund struct {
 	InitiatedBy        string       `gorm:"size:16"` // business/platform
 	CompletedAt        *time.Time
 }
+
+// ---- 订阅(recurring)----
+
+type SubStatus string
+
+const (
+	SubActive   SubStatus = "active"   // 已激活,正常续费
+	SubPastDue  SubStatus = "past_due" // 某期扣款失败,待恢复(invoice.payment_failed)
+	SubCanceled SubStatus = "canceled" // 已取消(主动/网关删除),终态
+)
+
+// Subscription 是"同一 entitlement 的跨期账本"(设计 §5.1)。单笔层(OrderV2/Attempt)
+// 与订阅层解耦:每期扣款仍落一张 renewal OrderV2,Subscription 只维护状态机 + 续费锚点。
+type Subscription struct {
+	Base
+	SubID            string    `gorm:"uniqueIndex;size:64;not null"` // pay 生成的逻辑订阅号
+	OutTradeNo       string    `gorm:"index;size:64;not null"`       // 首购 order(诞生订阅那笔)
+	MerchantID       uint64    `gorm:"index"`
+	BizSystem        string    `gorm:"index;size:32"`
+	BizRef           string    `gorm:"size:128"`
+	BizCode          string    `gorm:"index;size:64"` // 套餐码副本,续费事件带回
+	Channel          string    `gorm:"index;size:32;not null;uniqueIndex:uq_sub_provider"`
+	ProviderSubRef   string    `gorm:"size:128;not null;uniqueIndex:uq_sub_provider"` // 渠道订阅号(stripe sub id)
+	RecurringKind    string    `gorm:"size:24"`                                       // gateway_scheduled/token_offsession/...
+	AmountMinor      int64     `gorm:"not null"`
+	Currency         string    `gorm:"size:16;not null"`
+	Status           SubStatus `gorm:"index;size:16;not null"`
+	CurrentPeriodEnd *time.Time
+	CanceledAt       *time.Time
+}