diff --git a/internal/apps/payment/service.go b/internal/apps/payment/service.go
index 0758fc1d..412b21b3 100644
--- a/internal/apps/payment/service.go
+++ b/internal/apps/payment/service.go
@@ -204,7 +204,7 @@ func InitiatePayment(ctx context.Context, p *project.Project, payer *oauth.User,
 			return err
 		}
 		itemID = reservedItemID
-		logger.InfoF(ctx, "Reserved item %d for project %d and payer %d", itemID, p.ID, payer.ID)
+		logger.InfoF(ctx, "Reserved item %d for project %s and payer %d", itemID, p.ID, payer.ID)
 
 		outTradeNo := genOutTradeNo()
 		order := PaymentOrder{
@@ -315,14 +315,14 @@ func HandleNotify(ctx context.Context, q map[string]string) (bool, string) {
 		refundErr := doEpayRefund(ctx, cfg.ClientID, secret, order.TradeNo, moneyString(order.Amount))
 		if refundErr == nil {
 			tNow := time.Now()
-			if updateErr := db.DB(ctx).
-				Model(&PaymentOrder{}).
-				Where("out_trade_no = ?", outTradeNo).
-				Updates(map[string]any{"status": OrderStatusRefunded, "refunded_at": &tNow}).
-				Error; updateErr != nil {
+			processed, updateErr := markOrderRefundedAndReturnItem(ctx, &order, map[string]any{"status": OrderStatusRefunded, "refunded_at": &tNow}, OrderStatusRefunding)
+			if updateErr != nil {
+				logger.ErrorF(ctx, "payment refund retry: failed to mark order %s refunded: %v", outTradeNo, updateErr)
 				return false, "update order status failed"
 			}
-			db.Redis.RPush(ctx, project.ProjectItemsKey(order.ProjectID), order.ItemID)
+			if !processed {
+				return true, "idempotent"
+			}
 			return true, "refund retry ok"
 		}
 		return false, "refund retry failed"
@@ -359,13 +359,18 @@ func HandleNotify(ctx context.Context, q map[string]string) (bool, string) {
 			tNow := time.Now()
 			updates["status"] = OrderStatusRefunded
 			updates["refunded_at"] = &tNow
-			// 把 item 推回 Redis 队列恢复库存
-			db.Redis.RPush(ctx, project.ProjectItemsKey(order.ProjectID), order.ItemID)
+			if _, updateErr := markOrderRefundedAndReturnItem(ctx, &order, updates, OrderStatusPaid); updateErr != nil {
+				logger.ErrorF(ctx, "payment refund: failed to mark order %s refunded: %v", outTradeNo, updateErr)
+				return false, "update order status failed"
+			}
 		} else {
 			updates["status"] = OrderStatusRefunding
+			if updateErr := db.DB(ctx).Model(&PaymentOrder{}).
+				Where("out_trade_no = ? AND status = ?", outTradeNo, OrderStatusPaid).Updates(updates).Error; updateErr != nil {
+				logger.ErrorF(ctx, "payment refund: failed to mark order %s refunding: %v", outTradeNo, updateErr)
+				return false, "update order status failed"
+			}
 		}
-		db.DB(ctx).Model(&PaymentOrder{}).
-			Where("out_trade_no = ?", outTradeNo).Updates(updates)
 		// 让 epay 重试,再次进入时因状态非 PENDING 会回到 idempotent 分支
 		return false, fmt.Sprintf("fulfill failed: %v", err)
 	}
diff --git a/internal/apps/payment/tasks.go b/internal/apps/payment/tasks.go
index 1b74cc33..bcca8bea 100644
--- a/internal/apps/payment/tasks.go
+++ b/internal/apps/payment/tasks.go
@@ -29,9 +29,9 @@ import (
 	"time"
 
 	"github.com/hibiken/asynq"
-	"github.com/linux-do/cdk/internal/apps/project"
 	"github.com/linux-do/cdk/internal/db"
 	"github.com/linux-do/cdk/internal/logger"
+	"gorm.io/gorm"
 )
 
 // HandleExpireStaleOrders 清理长时间未付款的 PENDING 订单。
@@ -61,20 +61,37 @@ func HandleExpireStaleOrders(ctx context.Context, _ *asynq.Task) error {
 // expireOrder 通过 CAS 将单笔 PENDING 订单置为 FAILED，并把预占的 item 归还 Redis。
 // 使用 CAS (WHERE status=PENDING) 保证幂等：
 //   - 若 notify 回调恰好在此同时到达并推进了状态，CAS 得 0 行，安全跳过。
+//
+// 修复：归还 item 后，如果项目之前被标记为已完成，现在有库存了，则重置 IsCompleted。
 func expireOrder(ctx context.Context, order *PaymentOrder) {
-	rows := db.DB(ctx).Model(&PaymentOrder{}).
-		Where("out_trade_no = ? AND status = ?", order.OutTradeNo, OrderStatusPending).
-		Update("status", OrderStatusFailed).
-		RowsAffected
+	processed := false
+	if err := db.DB(ctx).Transaction(func(tx *gorm.DB) error {
+		result := tx.Model(&PaymentOrder{}).
+			Where("out_trade_no = ? AND status = ?", order.OutTradeNo, OrderStatusPending).
+			Update("status", OrderStatusFailed)
+		if result.Error != nil {
+			return result.Error
+		}
+		if result.RowsAffected == 0 {
+			return nil
+		}
 
-	// 另一协程（notify 回调）已处理，跳过
-	if rows == 0 {
+		if err := returnReservedItem(ctx, tx, order.ProjectID, order.ItemID); err != nil {
+			return err
+		}
+
+		processed = true
+		return nil
+	}); err != nil {
+		logger.ErrorF(ctx, "payment cleanup: failed to expire order %s: %v", order.OutTradeNo, err)
+		return
+	}
+
+	if !processed {
 		logger.InfoF(ctx, "payment cleanup: order %s already processed, skipping", order.OutTradeNo)
 		return
 	}
 
-	// 归还预占的 item，恢复项目库存
-	db.Redis.RPush(ctx, project.ProjectItemsKey(order.ProjectID), order.ItemID)
 	logger.InfoF(ctx, "payment cleanup: returned item %d to project %s stock", order.ItemID, order.ProjectID)
 	logger.InfoF(ctx, "payment cleanup: order %s expired and marked as FAILED", order.OutTradeNo)
 }
diff --git a/internal/apps/payment/utils.go b/internal/apps/payment/utils.go
new file mode 100644
index 00000000..59e5c50d
--- /dev/null
+++ b/internal/apps/payment/utils.go
@@ -0,0 +1,73 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 linux.do
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package payment
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/linux-do/cdk/internal/apps/project"
+	"github.com/linux-do/cdk/internal/db"
+	"gorm.io/gorm"
+)
+
+// returnReservedItem 把支付预占的 item 归还 Redis，并在同一个数据库事务中重置项目完成状态。
+// Redis RPush 或项目状态更新失败时返回 error，由调用方触发外层数据库事务回滚。
+func returnReservedItem(ctx context.Context, tx *gorm.DB, projectID string, itemID uint64) error {
+	var proj project.Project
+	if err := tx.Where("id = ?", projectID).First(&proj).Error; err != nil {
+		return fmt.Errorf("load project %s: %w", projectID, err)
+	}
+	if err := db.Redis.RPush(ctx, project.ProjectItemsKey(projectID), itemID).Err(); err != nil {
+		return fmt.Errorf("return item %d to project %s stock: %w", itemID, projectID, err)
+	}
+	if err := proj.ResetCompletedStatusIfHasStock(ctx, tx); err != nil {
+		return fmt.Errorf("reset completed status for project %s: %w", projectID, err)
+	}
+	return nil
+}
+
+func markOrderRefundedAndReturnItem(ctx context.Context, order *PaymentOrder, updates map[string]any, expectedStatus OrderStatus) (bool, error) {
+	processed := false
+	err := db.DB(ctx).Transaction(func(tx *gorm.DB) error {
+		result := tx.Model(&PaymentOrder{}).
+			Where("out_trade_no = ? AND status = ?", order.OutTradeNo, expectedStatus).
+			Updates(updates)
+		if result.Error != nil {
+			return result.Error
+		}
+		if result.RowsAffected == 0 {
+			return nil
+		}
+
+		if err := returnReservedItem(ctx, tx, order.ProjectID, order.ItemID); err != nil {
+			return err
+		}
+
+		processed = true
+		return nil
+	})
+	return processed, err
+}
diff --git a/internal/apps/project/models.go b/internal/apps/project/models.go
index 79576b24..d4f730d6 100644
--- a/internal/apps/project/models.go
+++ b/internal/apps/project/models.go
@@ -529,6 +529,27 @@ func (p *Project) GetReceivedItem(ctx context.Context, userID uint64) (*ProjectI
 	return item, nil
 }
 
+// ResetCompletedStatusIfHasStock 在调用方归还库存时重置项目完成状态。
+// 适用场景:
+//   - 付费订单退款成功后，item 被归还到 Redis 队列，需检查并重置项目完成状态
+//   - 付费订单超时过期后，预占的 item 被归还，需检查并重置项目完成状态
+//
+// 调用方应在归还 item 的同一个数据库事务中传入 tx；
+// 若 Redis RPush 或数据库更新失败，错误会返回给外层事务处理。
+func (p *Project) ResetCompletedStatusIfHasStock(ctx context.Context, tx *gorm.DB) error {
+	hasStock, err := p.HasStock(ctx)
+	if err != nil {
+		return err
+	}
+	if !hasStock {
+		return nil
+	}
+
+	return tx.Model(&Project{}).
+		Where("id = ? AND is_completed = ?", p.ID, true).
+		Update("is_completed", false).Error
+}
+
 type ProjectReport struct {
 	ID         uint64    `json:"id" gorm:"primaryKey,autoIncrement"`
 	ProjectID  string    `json:"project_id" gorm:"size:64;index;uniqueIndex:idx_project_reporter"`