diff --git a/backend/mci-server/src/main/java/com/sino/mci/admin/entity/UserRole.java b/backend/mci-server/src/main/java/com/sino/mci/admin/entity/UserRole.java
index 1f23dfb..2db48d9 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/admin/entity/UserRole.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/admin/entity/UserRole.java
@@ -1,24 +1,15 @@
 package com.sino.mci.admin.entity;
 
-import com.baomidou.mybatisplus.annotation.FieldFill;
-import com.baomidou.mybatisplus.annotation.IdType;
-import com.baomidou.mybatisplus.annotation.TableField;
-import com.baomidou.mybatisplus.annotation.TableId;
 import com.baomidou.mybatisplus.annotation.TableName;
+import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
-
-import java.time.LocalDateTime;
+import lombok.EqualsAndHashCode;
 
 @Data
+@EqualsAndHashCode(callSuper = true)
 @TableName("mci_user_role")
-public class UserRole {
-
-    @TableId(type = IdType.AUTO)
-    private Long id;
+public class UserRole extends BaseEntity {
 
     private Long userId;
     private Long roleId;
-
-    @TableField(fill = FieldFill.INSERT)
-    private LocalDateTime createTime;
 }
diff --git a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/Conversation.java b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/Conversation.java
index ae775a7..6fae84d 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/Conversation.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/Conversation.java
@@ -5,6 +5,12 @@ import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 
+/**
+ * 会话表（mci_conversation）。
+ * <p>
+ * 该表在 V15 已按 create_time 做 RANGE 月分区；MySQL 分区表不支持数据库级外键，
+ * 因此与会话相关的外键已在 V15 全部移除。引用完整性由应用层（MyBatis-Plus 逻辑删除 + 业务校验）维护。
+ */
 @Data
 @EqualsAndHashCode(callSuper = true)
 @TableName("mci_conversation")
diff --git a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationParticipant.java b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationParticipant.java
index b50cbb4..7f2be24 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationParticipant.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationParticipant.java
@@ -1,23 +1,20 @@
 package com.sino.mci.channel.entity;
 
-import com.baomidou.mybatisplus.annotation.IdType;
-import com.baomidou.mybatisplus.annotation.TableId;
 import com.baomidou.mybatisplus.annotation.TableName;
+import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
+import lombok.EqualsAndHashCode;
 
 import java.time.LocalDateTime;
 
 @Data
+@EqualsAndHashCode(callSuper = true)
 @TableName("mci_conversation_participant")
-public class ConversationParticipant {
-
-    @TableId(type = IdType.AUTO)
-    private Long id;
+public class ConversationParticipant extends BaseEntity {
 
     private Long conversationId;
     private Long personId;
     private Long channelIdentityId;
     private Integer participantType;
     private LocalDateTime joinTime;
-    private LocalDateTime createTime;
 }
diff --git a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationTagBinding.java b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationTagBinding.java
index 61cf603..d63267c 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationTagBinding.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/channel/entity/ConversationTagBinding.java
@@ -1,21 +1,16 @@
 package com.sino.mci.channel.entity;
 
-import com.baomidou.mybatisplus.annotation.IdType;
-import com.baomidou.mybatisplus.annotation.TableId;
 import com.baomidou.mybatisplus.annotation.TableName;
+import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
-
-import java.time.LocalDateTime;
+import lombok.EqualsAndHashCode;
 
 @Data
+@EqualsAndHashCode(callSuper = true)
 @TableName("mci_conversation_tag_binding")
-public class ConversationTagBinding {
-
-    @TableId(type = IdType.AUTO)
-    private Long id;
+public class ConversationTagBinding extends BaseEntity {
 
     private String tenantCode;
     private Long tagId;
     private Long conversationId;
-    private LocalDateTime createTime;
 }
diff --git a/backend/mci-server/src/main/java/com/sino/mci/crm/entity/PersonTagBinding.java b/backend/mci-server/src/main/java/com/sino/mci/crm/entity/PersonTagBinding.java
index 0dc3bee..b8d3fcd 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/crm/entity/PersonTagBinding.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/crm/entity/PersonTagBinding.java
@@ -1,21 +1,16 @@
 package com.sino.mci.crm.entity;
 
-import com.baomidou.mybatisplus.annotation.IdType;
-import com.baomidou.mybatisplus.annotation.TableId;
 import com.baomidou.mybatisplus.annotation.TableName;
+import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
-
-import java.time.LocalDateTime;
+import lombok.EqualsAndHashCode;
 
 @Data
+@EqualsAndHashCode(callSuper = true)
 @TableName("mci_person_tag_binding")
-public class PersonTagBinding {
-
-    @TableId(type = IdType.AUTO)
-    private Long id;
+public class PersonTagBinding extends BaseEntity {
 
     private String tenantCode;
     private Long tagId;
     private Long personId;
-    private LocalDateTime createTime;
 }
diff --git a/backend/mci-server/src/main/java/com/sino/mci/inbound/entity/FlowExecutionTrace.java b/backend/mci-server/src/main/java/com/sino/mci/inbound/entity/FlowExecutionTrace.java
index 5a40577..fbed501 100644
--- a/backend/mci-server/src/main/java/com/sino/mci/inbound/entity/FlowExecutionTrace.java
+++ b/backend/mci-server/src/main/java/com/sino/mci/inbound/entity/FlowExecutionTrace.java
@@ -1,13 +1,15 @@
 package com.sino.mci.inbound.entity;
 
 import com.baomidou.mybatisplus.annotation.TableName;
+import com.sino.mci.shared.entity.BaseEntity;
 import lombok.Data;
-import java.time.LocalDateTime;
+import lombok.EqualsAndHashCode;
 
 @Data
+@EqualsAndHashCode(callSuper = true)
 @TableName("mci_flow_execution_trace")
-public class FlowExecutionTrace {
-    private Long id;
+public class FlowExecutionTrace extends BaseEntity {
+
     private String eventId;
     private Long flowDefinitionId;
     private String nodeType;
@@ -17,5 +19,4 @@ public class FlowExecutionTrace {
     private Integer status;
     private Integer durationMs;
     private String errorMsg;
-    private LocalDateTime createTime;
 }
diff --git a/backend/mci-server/src/main/resources/db/migration/V17__audit_soft_delete_and_fk.sql b/backend/mci-server/src/main/resources/db/migration/V17__audit_soft_delete_and_fk.sql
new file mode 100644
index 0000000..146f7fc
--- /dev/null
+++ b/backend/mci-server/src/main/resources/db/migration/V17__audit_soft_delete_and_fk.sql
@@ -0,0 +1,93 @@
+-- Phase 1.6: 审计并补齐软删除/FK 一致性
+-- 目标：
+-- 1. 所有业务表必须具备 deleted 字段；对应实体继承 BaseEntity（含 @TableLogic 与自动填充）。
+-- 2. 唯一索引在软删除表中必须包含 deleted，避免已删除记录导致唯一冲突。
+-- 3. 记录 V15 分区改造后 mci_conversation 及其关联表不再支持数据库级外键的事实
+--    （MySQL 分区表不支持外键，应用层通过 MyBatis-Plus 逻辑删除保证引用完整性）。
+
+-- ============================
+-- 1. 补齐缺少 deleted/update_time 的业务表
+-- ============================
+
+-- 用户角色关系表
+ALTER TABLE mci_user_role
+    ADD COLUMN update_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP AFTER create_time,
+    ADD COLUMN deleted TINYINT NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删除 1已删除' AFTER update_time;
+
+-- 会话参与者表
+ALTER TABLE mci_conversation_participant
+    ADD COLUMN update_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP AFTER create_time,
+    ADD COLUMN deleted TINYINT NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删除 1已删除' AFTER update_time;
+
+-- 人员标签绑定表
+ALTER TABLE mci_person_tag_binding
+    ADD COLUMN update_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP AFTER create_time,
+    ADD COLUMN deleted TINYINT NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删除 1已删除' AFTER update_time;
+
+-- 会话标签绑定表
+ALTER TABLE mci_conversation_tag_binding
+    ADD COLUMN update_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP AFTER create_time,
+    ADD COLUMN deleted TINYINT NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删除 1已删除' AFTER update_time;
+
+-- 流程执行轨迹表
+ALTER TABLE mci_flow_execution_trace
+    ADD COLUMN update_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP AFTER create_time,
+    ADD COLUMN deleted TINYINT NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删除 1已删除' AFTER update_time;
+
+-- ============================
+-- 2. 统一唯一索引：软删除表的唯一索引必须包含 deleted
+-- ============================
+
+-- mci_tenant: 租户编码唯一（排除已删除）
+ALTER TABLE mci_tenant
+    DROP INDEX tenant_code,
+    ADD UNIQUE KEY uk_tenant_code (tenant_code, deleted);
+
+-- mci_platform_role: 角色编码唯一（排除已删除）
+ALTER TABLE mci_platform_role
+    DROP INDEX role_code,
+    ADD UNIQUE KEY uk_role_code (role_code, deleted);
+
+-- mci_user_role: 同一用户同一角色仅允许一条生效记录
+ALTER TABLE mci_user_role
+    DROP INDEX uk_user_role,
+    ADD UNIQUE KEY uk_user_role (user_id, role_id, deleted);
+
+-- mci_conversation_participant: 同一身份在同一会话中仅允许一条生效记录
+ALTER TABLE mci_conversation_participant
+    DROP INDEX uk_conv_participant,
+    ADD UNIQUE KEY uk_conv_participant (conversation_id, person_id, channel_identity_id, deleted);
+
+-- mci_channel_account_conversation: 同一账号同一会话同一绑定类型仅允许一条生效记录
+ALTER TABLE mci_channel_account_conversation
+    DROP INDEX uk_account_conv_binding,
+    ADD UNIQUE KEY uk_account_conv_binding (account_id, conversation_id, binding_type, deleted);
+
+-- mci_person_tag_binding: 同一标签同一人员仅允许一条生效记录
+ALTER TABLE mci_person_tag_binding
+    DROP INDEX uk_person_tag,
+    ADD UNIQUE KEY uk_person_tag (tag_id, person_id, deleted);
+
+-- mci_conversation_tag_binding: 同一标签同一会话仅允许一条生效记录
+ALTER TABLE mci_conversation_tag_binding
+    DROP INDEX uk_conversation_tag,
+    ADD UNIQUE KEY uk_conversation_tag (tag_id, conversation_id, deleted);
+
+-- mci_message_event: event_id 唯一（保留分区键 create_time）
+ALTER TABLE mci_message_event
+    DROP INDEX uk_event_id,
+    ADD UNIQUE KEY uk_event_id (event_id, deleted, create_time);
+
+-- mci_send_record: 任务维度唯一（保留分区键 create_time）
+ALTER TABLE mci_send_record
+    DROP INDEX uk_task_target,
+    ADD UNIQUE KEY uk_task_target (task_id, conversation_id, person_id, deleted, create_time);
+
+-- ============================
+-- 3. 分区表外键声明
+-- ============================
+-- V15 已完成 mci_conversation 分区改造，并删除了与会话表相关的数据库级外键约束：
+--   fk_participant_conversation_id、fk_binding_conversation_id、fk_conv_tag_conversation_id、
+--   fk_conversation_owner_account、fk_conversation_subject_id。
+-- 本迁移再次明确：mci_conversation 为 RANGE 分区表，MySQL 分区表不支持外键；
+-- 应用层通过 MyBatis-Plus 逻辑删除与业务校验维护引用完整性，不再恢复数据库级级联约束。