修复(#85): 促销系统 quantity 设计修正补丁（跨任务统一修复）

- subscribe_promo 表加 quantity 字段，BIGINT NOT NULL DEFAULT 1
- EvaluatePromo 加 quantity 参数，按 subscribeID + quantity 精确匹配
- Promo 从 Subscribe 顶层移到 SubscribeDiscount
- 查询加 quantity，返回 map[subscribeID][quantity] 二级映射
- recordPromoUsage 错误向上传播，不再静默吞掉
- preCreate 和 purchase 的 allowPromo 判定统一为 orderType==1
- 迁移脚本增加幂等处理（guarded DROP/ADD/MODIFY）

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

internal/logic/common/promoEligibility.go

@@ -27,13 +27,13 @@ type promoRuleParams struct {
 	InactiveMonths int `json:"inactive_months"`
 }
 
-func EvaluatePromo(ctx context.Context, svcCtx *svc.ServiceContext, userID int64, subscribeID int64) (*PromoResult, error) {
+func EvaluatePromo(ctx context.Context, svcCtx *svc.ServiceContext, userID int64, subscribeID int64, quantity int64) (*PromoResult, error) {
 	result := &PromoResult{}
-	if svcCtx == nil || svcCtx.PromoModel == nil || svcCtx.DB == nil || userID <= 0 || subscribeID <= 0 {
+	if svcCtx == nil || svcCtx.PromoModel == nil || svcCtx.DB == nil || userID <= 0 || subscribeID <= 0 || quantity <= 0 {
 		return result, nil
 	}
 
-	rules, err := svcCtx.PromoModel.QueryEligibleRules(ctx, subscribeID)
+	rules, err := svcCtx.PromoModel.QueryEligibleRules(ctx, subscribeID, quantity)
 	if err != nil {
 		return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "query promo rules failed: %v", err.Error())
 	}

internal/logic/public/order/preCreateOrderLogic.go

@@ -47,13 +47,18 @@ func (l *PreCreateOrderLogic) PreCreateOrder(req *types.PurchaseOrderRequest) (r
 		l.Debugf("[PreCreateOrder] Quantity is less than or equal to 0, setting to 1")
 		req.Quantity = 1
 	}
+	entitlement, entErr := commonLogic.ResolveEntitlementUser(l.ctx, l.svcCtx.DB, u.Id)
+	if entErr != nil {
+		return nil, entErr
+	}
 
 	targetSubscribeID := req.SubscribeId
+	orderType := uint8(1)
 	isSingleModeRenewal := false
 	decision, routeErr := commonLogic.ResolvePurchaseRoute(
 		l.ctx,
 		l.svcCtx.Config.Subscribe.SingleModel,
-		u.Id,
+		entitlement.EffectiveUserID,
 		req.SubscribeId,
 		l.svcCtx.UserModel.FindSingleModeAnchorSubscribe,
 	)
@@ -68,15 +73,44 @@ func (l *PreCreateOrderLogic) PreCreateOrder(req *types.PurchaseOrderRequest) (r
 		targetSubscribeID = decision.ResolvedSubscribeID
 		isSingleModeRenewal = decision.Route == commonLogic.PurchaseRoutePurchaseToRenewal
 		if isSingleModeRenewal && decision.Anchor != nil {
+			orderType = 2
 			l.Infow("[PreCreateOrder] single mode purchase routed to renewal preview",
 				logger.Field("mode", "single"),
 				logger.Field("route", "purchase_to_renewal"),
 				logger.Field("anchor_user_subscribe_id", decision.Anchor.Id),
 				logger.Field("user_id", u.Id),
+				logger.Field("effective_user_id", entitlement.EffectiveUserID),
 			)
 		}
 	}
 
+	// Keep promo eligibility preview aligned with Purchase: an existing paid subscription
+	// routes the request to renewal semantics, where first-purchase promos are disabled.
+	if !l.svcCtx.Config.Subscribe.SingleModel && orderType == 1 {
+		var existSub user.Subscribe
+		if e := l.svcCtx.DB.WithContext(l.ctx).
+			Model(&user.Subscribe{}).
+			Where("user_id = ? AND token != '' AND (order_id > 0 OR token LIKE 'iap:%')", entitlement.EffectiveUserID).
+			Order("expire_time DESC").
+			Order("updated_at DESC").
+			Order("id DESC").
+			First(&existSub).Error; e == nil && existSub.Id > 0 && existSub.Token != "" {
+			orderType = 2
+			l.Infow("[PreCreateOrder] purchase preview routed to renewal because an existing subscription was found",
+				logger.Field("route_mode", "global_single_subscription"),
+				logger.Field("route", "purchase_to_existing_subscription"),
+				logger.Field("existing_subscribe_id", existSub.Id),
+				logger.Field("existing_status", existSub.Status),
+				logger.Field("user_id", u.Id),
+				logger.Field("effective_user_id", entitlement.EffectiveUserID),
+				logger.Field("resolved_subscribe_id", targetSubscribeID),
+			)
+		} else if e != nil && !errors.Is(e, gorm.ErrRecordNotFound) {
+			l.Errorw("[PreCreateOrder] Database query error", logger.Field("error", e.Error()), logger.Field("user_id", u.Id))
+			return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "find existing subscription error: %v", e.Error())
+		}
+	}
+
 	// find subscribe plan
 	sub, err := l.svcCtx.SubscribeModel.FindOne(l.ctx, targetSubscribeID)
 	if err != nil {
@@ -86,7 +120,7 @@ func (l *PreCreateOrderLogic) PreCreateOrder(req *types.PurchaseOrderRequest) (r
 
 	// check subscribe plan quota limit for new purchase flow only
 	if !isSingleModeRenewal && sub.Quota > 0 {
-		userSub, err := l.svcCtx.UserModel.QueryUserSubscribe(l.ctx, u.Id)
+		userSub, err := l.svcCtx.UserModel.QueryUserSubscribe(l.ctx, entitlement.EffectiveUserID)
 		if err != nil {
 			l.Errorw("[PreCreateOrder] Database query error", logger.Field("error", err.Error()), logger.Field("user_id", u.Id))
 			return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "find user subscription error: %v", err.Error())
@@ -102,7 +136,7 @@ func (l *PreCreateOrderLogic) PreCreateOrder(req *types.PurchaseOrderRequest) (r
 		}
 	}
 
-	newUserDiscount, err := resolveNewUserDiscountEligibility(l.ctx, l.svcCtx.DB, u.Id, targetSubscribeID, req.Quantity, sub.Discount)
+	newUserDiscount, err := resolveNewUserDiscountEligibility(l.ctx, l.svcCtx.DB, entitlement.EffectiveUserID, targetSubscribeID, req.Quantity, sub.Discount)
 	if err != nil {
 		l.Errorw("[PreCreateOrder] Database query error resolving new user eligibility",
 			logger.Field("error", err.Error()),
@@ -117,13 +151,13 @@ func (l *PreCreateOrderLogic) PreCreateOrder(req *types.PurchaseOrderRequest) (r
 	priceResult, err := calculatePurchasePrice(
 		l.ctx,
 		l.svcCtx,
-		u.Id,
+		entitlement.EffectiveUserID,
 		targetSubscribeID,
 		sub.UnitPrice,
 		req.Quantity,
 		newUserDiscount.Discounts,
 		newUserDiscount.EligibleForDiscount,
-		!isSingleModeRenewal,
+		orderType == 1,
 	)
 	if err != nil {
 		l.Errorw("[PreCreateOrder] Promo price calculation error",

internal/logic/public/order/promoPricing.go

@@ -36,7 +36,7 @@ func calculatePurchasePrice(
 	}
 
 	if allowPromo {
-		promoResult, err := commonLogic.EvaluatePromo(ctx, svcCtx, userID, subscribeID)
+		promoResult, err := commonLogic.EvaluatePromo(ctx, svcCtx, userID, subscribeID, quantity)
 		if err != nil {
 			return nil, err
 		}

internal/logic/public/order/promoPricing_test.go

@@ -11,21 +11,30 @@ import (
 )
 
 type fakePromoModel struct {
-	rules []*promo.RuleWithPrice
+	rules            []*promo.RuleWithPrice
+	lastSubscribeID  int64
+	lastQuantity     int64
+	requireQuantity  int64
+	quantityMismatch []*promo.RuleWithPrice
 }
 
-func (m fakePromoModel) QueryEligibleRules(context.Context, int64) ([]*promo.RuleWithPrice, error) {
+func (m *fakePromoModel) QueryEligibleRules(_ context.Context, subscribeID int64, quantity int64) ([]*promo.RuleWithPrice, error) {
+	m.lastSubscribeID = subscribeID
+	m.lastQuantity = quantity
+	if m.requireQuantity > 0 && quantity != m.requireQuantity {
+		return m.quantityMismatch, nil
+	}
 	return m.rules, nil
 }
 
-func (m fakePromoModel) InsertUsage(context.Context, *promo.Usage, ...*gorm.DB) error {
+func (m *fakePromoModel) InsertUsage(context.Context, *promo.Usage, ...*gorm.DB) error {
 	return nil
 }
 
 func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 	svcCtx := &svc.ServiceContext{
 		DB: &gorm.DB{},
-		PromoModel: fakePromoModel{rules: []*promo.RuleWithPrice{
+		PromoModel: &fakePromoModel{rules: []*promo.RuleWithPrice{
 			{
 				Rule: promo.Rule{
 					Id:      9,
@@ -73,7 +82,7 @@ func TestCalculatePurchasePricePromoSkipsPercentDiscount(t *testing.T) {
 func TestCalculatePurchasePriceIgnoresInvalidPromoPrice(t *testing.T) {
 	svcCtx := &svc.ServiceContext{
 		DB: &gorm.DB{},
-		PromoModel: fakePromoModel{rules: []*promo.RuleWithPrice{
+		PromoModel: &fakePromoModel{rules: []*promo.RuleWithPrice{
 			{
 				Rule: promo.Rule{
 					Id:      10,
@@ -111,3 +120,52 @@ func TestCalculatePurchasePriceIgnoresInvalidPromoPrice(t *testing.T) {
 		t.Fatalf("promo fields = (%d, %d), want (0, 0)", result.PromoRuleId, result.PromoDiscount)
 	}
 }
+
+func TestCalculatePurchasePricePassesQuantityToPromoEvaluation(t *testing.T) {
+	promoModel := &fakePromoModel{
+		requireQuantity: 6,
+		rules: []*promo.RuleWithPrice{
+			{
+				Rule: promo.Rule{
+					Id:      11,
+					Name:    "quantity campaign",
+					Type:    promo.RuleTypeCampaign,
+					Enabled: true,
+				},
+				PromoPrice: 500,
+			},
+		},
+	}
+	svcCtx := &svc.ServiceContext{
+		DB:         &gorm.DB{},
+		PromoModel: promoModel,
+	}
+
+	result, err := calculatePurchasePrice(
+		context.Background(),
+		svcCtx,
+		1,
+		2,
+		1000,
+		6,
+		[]types.SubscribeDiscount{{Quantity: 6, Discount: 80}},
+		true,
+		true,
+	)
+	if err != nil {
+		t.Fatalf("calculatePurchasePrice returned error: %v", err)
+	}
+
+	if promoModel.lastSubscribeID != 2 {
+		t.Fatalf("lastSubscribeID = %d, want 2", promoModel.lastSubscribeID)
+	}
+	if promoModel.lastQuantity != 6 {
+		t.Fatalf("lastQuantity = %d, want 6", promoModel.lastQuantity)
+	}
+	if result.PayableBase != 3000 {
+		t.Fatalf("PayableBase = %d, want 3000", result.PayableBase)
+	}
+	if result.PromoRuleId != 11 {
+		t.Fatalf("PromoRuleId = %d, want 11", result.PromoRuleId)
+	}
+}

internal/logic/public/subscribe/promo.go

@@ -57,6 +57,12 @@ func loadSubscribePromoMap(ctx context.Context, svcCtx *svc.ServiceContext, subs
 	evaluator := promoEligibilityEvaluator{ctx: ctx, db: svcCtx.DB, userInfo: userInfo}
 	now := time.Now()
 	for _, candidate := range candidates {
+		if candidate.Quantity <= 0 {
+			continue
+		}
+		if result[candidate.SubscribeId] == nil {
+			result[candidate.SubscribeId] = make(map[int64]*types.SubscribePromo)
+		}
 		if _, exists := result[candidate.SubscribeId][candidate.Quantity]; exists {
 			continue
 		}
@@ -70,9 +76,6 @@ func loadSubscribePromoMap(ctx context.Context, svcCtx *svc.ServiceContext, subs
 		if !ok {
 			continue
 		}
-		if _, exists := result[candidate.SubscribeId]; !exists {
-			result[candidate.SubscribeId] = make(map[int64]*types.SubscribePromo)
-		}
 		result[candidate.SubscribeId][candidate.Quantity] = &types.SubscribePromo{
 			RuleName:   candidate.RuleName,
 			RuleType:   candidate.RuleType,

internal/model/promo/model.go

@@ -13,7 +13,7 @@ type RuleWithPrice struct {
 }
 
 type Model interface {
-	QueryEligibleRules(ctx context.Context, subscribeId int64) ([]*RuleWithPrice, error)
+	QueryEligibleRules(ctx context.Context, subscribeId int64, quantity int64) ([]*RuleWithPrice, error)
 	InsertUsage(ctx context.Context, data *Usage, tx ...*gorm.DB) error
 }
 
@@ -25,13 +25,13 @@ func NewModel(db *gorm.DB, _ *redis.Client) Model {
 	return &defaultPromoModel{db: db}
 }
 
-func (m *defaultPromoModel) QueryEligibleRules(ctx context.Context, subscribeId int64) ([]*RuleWithPrice, error) {
+func (m *defaultPromoModel) QueryEligibleRules(ctx context.Context, subscribeId int64, quantity int64) ([]*RuleWithPrice, error) {
 	var list []*RuleWithPrice
 	err := m.db.WithContext(ctx).
 		Table("promo_rule AS pr").
 		Select("pr.*, sp.promo_price").
 		Joins("JOIN subscribe_promo AS sp ON sp.promo_rule_id = pr.id").
-		Where("sp.subscribe_id = ? AND sp.promo_price > 0 AND pr.enabled = ?", subscribeId, true).
+		Where("sp.subscribe_id = ? AND sp.quantity = ? AND sp.promo_price > 0 AND pr.enabled = ?", subscribeId, quantity, true).
 		Where("pr.deleted_at IS NULL").
 		Order("pr.priority DESC").
 		Order("pr.id ASC").

internal/model/promo/promo.go

@@ -33,6 +33,7 @@ func (Rule) TableName() string {
 type SubscribePromo struct {
 	Id          int64     `gorm:"primaryKey"`
 	SubscribeId int64     `gorm:"type:bigint unsigned;not null;comment:Subscribe ID"`
+	Quantity    int64     `gorm:"type:bigint;not null;default:1;comment:Quantity"`
 	PromoRuleId int64     `gorm:"type:bigint unsigned;not null;comment:Promo Rule ID"`
 	PromoPrice  int64     `gorm:"type:bigint;not null;default:0;comment:Promo Price"`
 	CreatedAt   time.Time `gorm:"<-:create;comment:Create Time"`