diff --git a/src/ai-coach/ai-coach.service.ts b/src/ai-coach/ai-coach.service.ts
index e5b0b31..1fa457a 100644
--- a/src/ai-coach/ai-coach.service.ts
+++ b/src/ai-coach/ai-coach.service.ts
@@ -54,7 +54,7 @@ export class AiCoachService {
 
   buildChatHistory = async (userId: string, conversationId: string) => {
     const history = await AiMessage.findAll({
-      where: { userId, conversationId },
+      where: { userId, conversationId, deleted: false },
       order: [['created_at', 'ASC']],
     });
 
@@ -128,7 +128,7 @@ export class AiCoachService {
     const pageSize = Math.min(50, Math.max(1, params.pageSize || 20));
     const offset = (page - 1) * pageSize;
     const { rows, count } = await AiConversation.findAndCountAll({
-      where: { userId },
+      where: { userId, deleted: false },
       order: [['last_message_at', 'DESC']],
       offset,
       limit: pageSize,
@@ -147,10 +147,10 @@ export class AiCoachService {
   }
 
   async getConversationDetail(userId: string, conversationId: string) {
-    const conv = await AiConversation.findOne({ where: { id: conversationId, userId } });
+    const conv = await AiConversation.findOne({ where: { id: conversationId, userId, deleted: false } });
     if (!conv) return null;
     const messages = await AiMessage.findAll({
-      where: { userId, conversationId },
+      where: { userId, conversationId, deleted: false },
       order: [['created_at', 'ASC']],
     });
     return {
@@ -163,10 +163,10 @@ export class AiCoachService {
   }
 
   async deleteConversation(userId: string, conversationId: string): Promise<boolean> {
-    const conv = await AiConversation.findOne({ where: { id: conversationId, userId } });
+    const conv = await AiConversation.findOne({ where: { id: conversationId, userId, deleted: false } });
     if (!conv) return false;
-    await AiMessage.destroy({ where: { userId, conversationId } });
-    await AiConversation.destroy({ where: { id: conversationId, userId } });
+    await AiMessage.update({ deleted: true }, { where: { userId, conversationId } });
+    await AiConversation.update({ deleted: true }, { where: { id: conversationId, userId } });
     return true;
   }
 
diff --git a/src/ai-coach/models/ai-conversation.model.ts b/src/ai-coach/models/ai-conversation.model.ts
index 75e4c14..dc66530 100644
--- a/src/ai-coach/models/ai-conversation.model.ts
+++ b/src/ai-coach/models/ai-conversation.model.ts
@@ -46,6 +46,13 @@ export class AiConversation extends Model {
   })
   declare updatedAt: Date;
 
+  @Column({
+    type: DataType.BOOLEAN,
+    allowNull: false,
+    defaultValue: false,
+  })
+  declare deleted: boolean;
+
   @HasMany(() => AiMessage)
   declare messages?: AiMessage[];
 }
diff --git a/src/ai-coach/models/ai-message.model.ts b/src/ai-coach/models/ai-message.model.ts
index 51f3174..9b13adb 100644
--- a/src/ai-coach/models/ai-message.model.ts
+++ b/src/ai-coach/models/ai-message.model.ts
@@ -65,6 +65,13 @@ export class AiMessage extends Model {
   })
   declare updatedAt: Date;
 
+  @Column({
+    type: DataType.BOOLEAN,
+    allowNull: false,
+    defaultValue: false,
+  })
+  declare deleted: boolean;
+
   @BelongsTo(() => AiConversation)
   declare conversation?: AiConversation;
 }
diff --git a/src/checkins/checkins.service.ts b/src/checkins/checkins.service.ts
index 9477cf9..8a018c4 100644
--- a/src/checkins/checkins.service.ts
+++ b/src/checkins/checkins.service.ts
@@ -19,6 +19,21 @@ export class CheckinsService {
   ) { }
 
   async create(dto: CreateCheckinDto): Promise<CheckinResponseDto> {
+    // 检查是否已存在未删除的记录
+    const existingRecord = await this.checkinModel.findOne({
+      where: {
+        userId: dto.userId,
+        workoutId: dto.workoutId || null,
+        planId: dto.planId || null,
+        checkinDate: dto.checkinDate || null,
+        deleted: false,
+      },
+    });
+
+    if (existingRecord) {
+      return { code: ResponseCode.SUCCESS, message: 'success', data: existingRecord.toJSON() };
+    }
+
     const record = await this.checkinModel.create({
       userId: dto.userId,
       workoutId: dto.workoutId || null,
@@ -43,7 +58,12 @@ export class CheckinsService {
   }
 
   async update(dto: UpdateCheckinDto, userId: string): Promise<CheckinResponseDto> {
-    const record = await this.checkinModel.findByPk(dto.id);
+    const record = await this.checkinModel.findOne({
+      where: {
+        id: dto.id,
+        deleted: false,
+      },
+    });
     if (!record) {
       throw new NotFoundException('打卡记录不存在');
     }
@@ -75,7 +95,12 @@ export class CheckinsService {
   }
 
   async complete(dto: CompleteCheckinDto, userId: string): Promise<CheckinResponseDto> {
-    const record = await this.checkinModel.findByPk(dto.id);
+    const record = await this.checkinModel.findOne({
+      where: {
+        id: dto.id,
+        deleted: false,
+      },
+    });
     if (!record) {
       throw new NotFoundException('打卡记录不存在');
     }
@@ -114,7 +139,8 @@ export class CheckinsService {
     if (record.userId !== userId) {
       throw new ForbiddenException('无权操作该打卡记录');
     }
-    await record.destroy();
+    record.deleted = true;
+    await record.save();
     await this.activityLogsService.record({
       userId: record.userId,
       entityType: ActivityEntityType.CHECKIN,
@@ -139,6 +165,7 @@ export class CheckinsService {
     const rows = await this.checkinModel.findAll({
       where: {
         userId,
+        deleted: false,
         [Op.or]: [
           { checkinDate: target.format('YYYY-MM-DD') as any },
           {
@@ -170,6 +197,7 @@ export class CheckinsService {
     const rows = await this.checkinModel.findAll({
       where: {
         userId,
+        deleted: false,
         [Op.or]: [
           {
             checkinDate: {
diff --git a/src/checkins/models/checkin.model.ts b/src/checkins/models/checkin.model.ts
index bd91310..f8c3c84 100644
--- a/src/checkins/models/checkin.model.ts
+++ b/src/checkins/models/checkin.model.ts
@@ -111,6 +111,12 @@ export class Checkin extends Model {
     defaultValue: DataType.NOW,
   })
   declare updatedAt: Date;
+
+  @Column({
+    type: DataType.BOOLEAN,
+    defaultValue: false,
+  })
+  declare deleted: boolean;
 }