diff --git a/Fabric.Backend.Guild/src/entities/message.entity.ts b/Fabric.Backend.Guild/src/entities/message.entity.ts
index 83bfebe..65eaa4a 100644
--- a/Fabric.Backend.Guild/src/entities/message.entity.ts
+++ b/Fabric.Backend.Guild/src/entities/message.entity.ts
@@ -9,6 +9,10 @@ export class Message {
   @PrimaryGeneratedColumn('uuid')
   id!: string;
 
+  @Index()
+  @Column({ type: 'varchar', length: 80, unique: true })
+  messageId!: string;
+
   @Index()
   @Column({ type: 'char', length: 36, nullable: true })
   channelId!: string | null;
@@ -26,6 +30,24 @@ export class Message {
   @Column({ type: 'text' })
   content!: string;
 
+  @Column({ type: 'varchar', length: 80, nullable: true })
+  replyToMessageId!: string | null;
+
+  @Column({ type: 'json', nullable: true })
+  mentions!: string[] | null;
+
+  @Column({ type: 'json', nullable: true })
+  attachments!: Array<{ url: string; name?: string; mimeType?: string }> | null;
+
+  @Column({ type: 'datetime', nullable: true })
+  editedAt!: Date | null;
+
+  @Column({ type: 'datetime', nullable: true })
+  deletedAt!: Date | null;
+
+  @Column({ type: 'boolean', default: false })
+  isDeleted!: boolean;
+
   @CreateDateColumn()
   @Index()
   createdAt!: Date;
diff --git a/Fabric.Backend.Guild/src/messaging/messaging.controller.ts b/Fabric.Backend.Guild/src/messaging/messaging.controller.ts
index cb5bb1e..7db165a 100644
--- a/Fabric.Backend.Guild/src/messaging/messaging.controller.ts
+++ b/Fabric.Backend.Guild/src/messaging/messaging.controller.ts
@@ -1,19 +1,19 @@
-import { Body, Controller, Delete, Get, Param, Patch, Post, Query } from '@nestjs/common';
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  NotFoundException,
+  Param,
+  Patch,
+  Post,
+  Query,
+} from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { DataSource, Repository } from 'typeorm';
 import { CreateMessageDto } from './dto.create-message.dto';
-
-type Message = {
-  messageId: string;
-  seq: number;
-  content: string;
-  authorUserId: string;
-  replyToMessageId: string | null;
-  mentions: string[];
-  attachments: Array<{ url: string; name?: string; mimeType?: string }>;
-  createdAt: string;
-  editedAt: string | null;
-  deletedAt: string | null;
-  isDeleted: boolean;
-};
+import { Channel } from '../entities/channel.entity';
+import { Message } from '../entities/message.entity';
 
 const EDIT_WINDOW_MS = 15 * 60 * 1000;
 const DEFAULT_PAGE_LIMIT = 50;
@@ -21,39 +21,73 @@ const MAX_PAGE_LIMIT = 200;
 
 @Controller('channels/:id/messages')
 export class MessagingController {
-  private seqByChannel = new Map<string, number>();
-  private messagesByChannel = new Map<string, Message[]>();
+  constructor(
+    private readonly dataSource: DataSource,
+    @InjectRepository(Channel)
+    private readonly channelRepo: Repository<Channel>,
+    @InjectRepository(Message)
+    private readonly messageRepo: Repository<Message>,
+  ) {}
+
+  private toView(m: Message) {
+    return {
+      messageId: m.messageId,
+      seq: m.seq,
+      content: m.content,
+      authorUserId: m.authorUserId,
+      replyToMessageId: m.replyToMessageId,
+      mentions: m.mentions ?? [],
+      attachments: m.attachments ?? [],
+      createdAt: m.createdAt.toISOString(),
+      editedAt: m.editedAt ? m.editedAt.toISOString() : null,
+      deletedAt: m.deletedAt ? m.deletedAt.toISOString() : null,
+      isDeleted: m.isDeleted,
+    };
+  }
 
   @Post()
-  create(@Param('id') channelId: string, @Body() body: CreateMessageDto) {
-    const next = (this.seqByChannel.get(channelId) ?? 0) + 1;
-    this.seqByChannel.set(channelId, next);
+  async create(@Param('id') channelId: string, @Body() body: CreateMessageDto) {
+    const message = await this.dataSource.transaction(async (manager) => {
+      const channel = await manager.findOne(Channel, {
+        where: { id: channelId },
+        lock: { mode: 'pessimistic_write' },
+      });
+      if (!channel) {
+        throw new NotFoundException('channel not found');
+      }
 
-    const message: Message = {
-      messageId: body.clientMessageId ?? `m-${channelId}-${next}`,
-      seq: next,
-      content: body.content,
-      authorUserId: body.authorUserId ?? 'anonymous',
-      replyToMessageId: body.replyToMessageId ?? null,
-      mentions: body.mentions ?? [],
-      attachments: body.attachments ?? [],
-      createdAt: new Date().toISOString(),
-      editedAt: null,
-      deletedAt: null,
-      isDeleted: false,
-    };
+      const nextSeq = channel.lastSeq + 1;
+      channel.lastSeq = nextSeq;
+      await manager.save(Channel, channel);
 
-    const arr = this.messagesByChannel.get(channelId) ?? [];
-    arr.push(message);
-    this.messagesByChannel.set(channelId, arr);
+      const messageId = body.clientMessageId ?? `m-${channelId}-${nextSeq}`;
+      const row = manager.create(Message, {
+        messageId,
+        channelId,
+        conversationId: null,
+        authorUserId: body.authorUserId ?? 'anonymous',
+        seq: nextSeq,
+        content: body.content,
+        replyToMessageId: body.replyToMessageId ?? null,
+        mentions: body.mentions ?? [],
+        attachments: body.attachments ?? [],
+        editedAt: null,
+        deletedAt: null,
+        isDeleted: false,
+      });
+      return manager.save(Message, row);
+    });
 
-    return message;
+    return this.toView(message);
   }
 
   @Patch(':messageId')
-  edit(@Param('id') channelId: string, @Param('messageId') messageId: string, @Body() body: { content?: string }) {
-    const arr = this.messagesByChannel.get(channelId) ?? [];
-    const item = arr.find((m) => m.messageId === messageId);
+  async edit(
+    @Param('id') channelId: string,
+    @Param('messageId') messageId: string,
+    @Body() body: { content?: string },
+  ) {
+    const item = await this.messageRepo.findOne({ where: { channelId, messageId } });
     if (!item) return { status: 'not_found' };
 
     const now = Date.now();
@@ -63,27 +97,28 @@ export class MessagingController {
     }
 
     item.content = body.content ?? item.content;
-    item.editedAt = new Date().toISOString();
-    return item;
+    item.editedAt = new Date();
+    const saved = await this.messageRepo.save(item);
+    return this.toView(saved);
   }
 
   @Delete(':messageId')
-  remove(@Param('id') channelId: string, @Param('messageId') messageId: string) {
-    const arr = this.messagesByChannel.get(channelId) ?? [];
-    const item = arr.find((m) => m.messageId === messageId);
+  async remove(@Param('id') channelId: string, @Param('messageId') messageId: string) {
+    const item = await this.messageRepo.findOne({ where: { channelId, messageId } });
     if (!item) return { status: 'not_found' };
 
     item.isDeleted = true;
-    item.deletedAt = new Date().toISOString();
+    item.deletedAt = new Date();
     item.content = '[deleted]';
     item.mentions = [];
     item.attachments = [];
+    await this.messageRepo.save(item);
 
     return { status: 'deleted', mode: 'soft', messageId };
   }
 
   @Get()
-  listBySeq(
+  async listBySeq(
     @Param('id') channelId: string,
     @Query('seq_from') seqFrom?: string,
     @Query('seq_to') seqTo?: string,
@@ -96,9 +131,17 @@ export class MessagingController {
       Number.isFinite(requestedLimit) && requestedLimit > 0
         ? Math.min(requestedLimit, MAX_PAGE_LIMIT)
         : DEFAULT_PAGE_LIMIT;
-    const arr = this.messagesByChannel.get(channelId) ?? [];
-    const filtered = arr.filter((m) => m.seq >= from && m.seq <= to);
-    const items = filtered.slice(0, safeLimit);
+
+    const qb = this.messageRepo
+      .createQueryBuilder('m')
+      .where('m.channelId = :channelId', { channelId })
+      .andWhere('m.seq >= :from', { from })
+      .andWhere('m.seq <= :to', { to })
+      .orderBy('m.seq', 'ASC');
+
+    const total = await qb.getCount();
+    const rows = await qb.limit(safeLimit).getMany();
+    const items = rows.map((m) => this.toView(m));
 
     return {
       items,
@@ -107,7 +150,7 @@ export class MessagingController {
         seqTo: to,
         limit: safeLimit,
         returned: items.length,
-        hasMore: filtered.length > items.length,
+        hasMore: total > items.length,
       },
     };
   }
diff --git a/Fabric.Backend.Guild/src/messaging/messaging.module.ts b/Fabric.Backend.Guild/src/messaging/messaging.module.ts
index 9133ca9..1ed52ac 100644
--- a/Fabric.Backend.Guild/src/messaging/messaging.module.ts
+++ b/Fabric.Backend.Guild/src/messaging/messaging.module.ts
@@ -1,7 +1,11 @@
 import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
 import { MessagingController } from './messaging.controller';
+import { Channel } from '../entities/channel.entity';
+import { Message } from '../entities/message.entity';
 
 @Module({
+  imports: [TypeOrmModule.forFeature([Channel, Message])],
   controllers: [MessagingController],
 })
 export class MessagingModule {}
diff --git a/docs/TODO-backend-center-guild.md b/docs/TODO-backend-center-guild.md
index 44f3931..6214dcf 100644
--- a/docs/TODO-backend-center-guild.md
+++ b/docs/TODO-backend-center-guild.md
@@ -48,7 +48,7 @@
 - [x] 编辑消息（可编辑窗口策略先简化）
 - [x] 删除消息（软删 vs 硬删，先定策略）
 - [x] `GET messages` 分页（seq 区间 + limit）
-- [ ] seq 分配改为 DB 原子方案（避免并发冲突）
+- [x] seq 分配改为 DB 原子方案（避免并发冲突）
 
 ### 2.3 一致性与回补
 - [ ] 回补接口：`seq_from/seq_to`