feat(messaging): add in-app messaging module with Conversation + Message models

Implements buyer-agent in-app messaging (Task 8.4): - Prisma models: Conversation, ConversationParticipant, Message - Full DDD module: domain entities, repository interfaces, CQRS commands/queries - REST API: POST/GET conversations, POST/GET messages, PATCH read, DELETE messages - WebSocket gateway (/messaging namespace): real-time message delivery, typing indicators, room-based routing - 46 unit tests covering handlers, repositories, controller, and gateway Co-Authored-By: Paperclip <noreply@paperclip.ing>
2026-04-16 05:36:04 +07:00
parent 30d3039b94
commit 3b5da2dcf9
37 changed files with 2310 additions and 0 deletions
--- a/apps/api/src/app.module.ts
+++ b/apps/api/src/app.module.ts
@@ -13,6 +13,7 @@ import { InquiriesModule } from '@modules/inquiries';
 import { LeadsModule } from '@modules/leads';
 import { ListingsModule } from '@modules/listings';
 import { McpIntegrationModule } from '@modules/mcp';
+import { MessagingModule } from '@modules/messaging';
 import { HttpMetricsInterceptor, MetricsModule } from '@modules/metrics';
 import { NotificationsModule } from '@modules/notifications';
 import { PaymentsModule } from '@modules/payments';
@@ -46,6 +47,7 @@ import { AppController } from './app.controller';
    AnalyticsModule,
    MetricsModule,
    McpIntegrationModule,
+    MessagingModule,

    // ── Rate Limiting ──
    // Default: 60 requests per 60 seconds per IP
--- a/apps/api/src/modules/messaging/application/tests/create-conversation.handler.spec.ts
+++ b/apps/api/src/modules/messaging/application/tests/create-conversation.handler.spec.ts
@@ -0,0 +1,133 @@
+import { CreateConversationCommand } from '../commands/create-conversation/create-conversation.command';
+import { CreateConversationHandler } from '../commands/create-conversation/create-conversation.handler';
+
+describe('CreateConversationHandler', () => {
+  let handler: CreateConversationHandler;
+  let mockConversationRepo: {
+    create: ReturnType<typeof vi.fn>;
+    findExistingBetweenUsers: ReturnType<typeof vi.fn>;
+    updateLastMessage: ReturnType<typeof vi.fn>;
+    incrementUnreadCount: ReturnType<typeof vi.fn>;
+    findById: ReturnType<typeof vi.fn>;
+  };
+  let mockMessageRepo: {
+    create: ReturnType<typeof vi.fn>;
+  };
+  let mockEventBus: { publish: ReturnType<typeof vi.fn> };
+  let mockLogger: { log: ReturnType<typeof vi.fn>; warn: ReturnType<typeof vi.fn>; error: ReturnType<typeof vi.fn> };
+
+  const conversationEntity = {
+    id: 'conv-1',
+    listingId: 'listing-1',
+    subject: null,
+    status: 'ACTIVE' as const,
+    lastMessage: null,
+    lastMessageAt: null,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+    participants: [
+      { id: 'p-1', conversationId: 'conv-1', userId: 'user-1', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+      { id: 'p-2', conversationId: 'conv-1', userId: 'user-2', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+    ],
+  };
+
+  const messageEntity = {
+    id: 'msg-1',
+    conversationId: 'conv-1',
+    senderId: 'user-1',
+    type: 'TEXT' as const,
+    content: 'Hello!',
+    metadata: null,
+    editedAt: null,
+    deletedAt: null,
+    createdAt: new Date(),
+  };
+
+  beforeEach(() => {
+    mockConversationRepo = {
+      create: vi.fn().mockResolvedValue(conversationEntity),
+      findExistingBetweenUsers: vi.fn().mockResolvedValue(null),
+      updateLastMessage: vi.fn().mockResolvedValue(undefined),
+      incrementUnreadCount: vi.fn().mockResolvedValue(undefined),
+      findById: vi.fn(),
+    };
+    mockMessageRepo = {
+      create: vi.fn().mockResolvedValue(messageEntity),
+    };
+    mockEventBus = { publish: vi.fn() };
+    mockLogger = { log: vi.fn(), warn: vi.fn(), error: vi.fn() };
+
+    handler = new CreateConversationHandler(
+      mockConversationRepo as any,
+      mockMessageRepo as any,
+      mockEventBus as any,
+      mockLogger as any,
+    );
+  });
+
+  it('creates a new conversation with participants', async () => {
+    const command = new CreateConversationCommand('user-1', 'user-2', 'listing-1');
+
+    const result = await handler.execute(command);
+
+    expect(mockConversationRepo.findExistingBetweenUsers).toHaveBeenCalledWith(
+      ['user-1', 'user-2'],
+      'listing-1',
+    );
+    expect(mockConversationRepo.create).toHaveBeenCalledWith({
+      listingId: 'listing-1',
+      subject: undefined,
+      participantUserIds: ['user-1', 'user-2'],
+    });
+    expect(result.id).toBe('conv-1');
+  });
+
+  it('creates conversation with initial message', async () => {
+    const command = new CreateConversationCommand('user-1', 'user-2', 'listing-1', undefined, 'Hello!');
+
+    await handler.execute(command);
+
+    expect(mockMessageRepo.create).toHaveBeenCalledWith({
+      conversationId: 'conv-1',
+      senderId: 'user-1',
+      type: 'TEXT',
+      content: 'Hello!',
+    });
+    expect(mockConversationRepo.updateLastMessage).toHaveBeenCalled();
+    expect(mockConversationRepo.incrementUnreadCount).toHaveBeenCalledWith('conv-1', 'user-1');
+    expect(mockEventBus.publish).toHaveBeenCalled();
+  });
+
+  it('returns existing conversation when one exists between users', async () => {
+    mockConversationRepo.findExistingBetweenUsers.mockResolvedValue(conversationEntity);
+
+    const command = new CreateConversationCommand('user-1', 'user-2', 'listing-1');
+
+    const result = await handler.execute(command);
+
+    expect(result.id).toBe('conv-1');
+    expect(mockConversationRepo.create).not.toHaveBeenCalled();
+  });
+
+  it('sends message in existing conversation when initial message provided', async () => {
+    mockConversationRepo.findExistingBetweenUsers.mockResolvedValue(conversationEntity);
+
+    const command = new CreateConversationCommand('user-1', 'user-2', 'listing-1', undefined, 'Hello again!');
+
+    await handler.execute(command);
+
+    expect(mockConversationRepo.create).not.toHaveBeenCalled();
+    expect(mockMessageRepo.create).toHaveBeenCalledWith({
+      conversationId: 'conv-1',
+      senderId: 'user-1',
+      type: 'TEXT',
+      content: 'Hello again!',
+    });
+  });
+
+  it('throws when creating conversation with yourself', async () => {
+    const command = new CreateConversationCommand('user-1', 'user-1');
+
+    await expect(handler.execute(command)).rejects.toThrow('Không thể tạo hội thoại với chính mình');
+  });
+});
--- a/apps/api/src/modules/messaging/application/tests/get-conversations.handler.spec.ts
+++ b/apps/api/src/modules/messaging/application/tests/get-conversations.handler.spec.ts
@@ -0,0 +1,44 @@
+import { GetConversationsHandler } from '../queries/get-conversations/get-conversations.handler';
+import { GetConversationsQuery } from '../queries/get-conversations/get-conversations.query';
+
+describe('GetConversationsHandler', () => {
+  let handler: GetConversationsHandler;
+  let mockConversationRepo: {
+    findByUserId: ReturnType<typeof vi.fn>;
+    countByUserId: ReturnType<typeof vi.fn>;
+  };
+
+  const conversations = [
+    {
+      id: 'conv-1',
+      listingId: 'listing-1',
+      subject: null,
+      status: 'ACTIVE',
+      lastMessage: 'Hello!',
+      lastMessageAt: new Date(),
+      createdAt: new Date(),
+      updatedAt: new Date(),
+      participants: [],
+    },
+  ];
+
+  beforeEach(() => {
+    mockConversationRepo = {
+      findByUserId: vi.fn().mockResolvedValue(conversations),
+      countByUserId: vi.fn().mockResolvedValue(1),
+    };
+
+    handler = new GetConversationsHandler(mockConversationRepo as any);
+  });
+
+  it('returns conversations with total count', async () => {
+    const query = new GetConversationsQuery('user-1', 20, 0);
+
+    const result = await handler.execute(query);
+
+    expect(result.conversations).toHaveLength(1);
+    expect(result.total).toBe(1);
+    expect(mockConversationRepo.findByUserId).toHaveBeenCalledWith('user-1', 20, 0);
+    expect(mockConversationRepo.countByUserId).toHaveBeenCalledWith('user-1');
+  });
+});
--- a/apps/api/src/modules/messaging/application/tests/get-messages.handler.spec.ts
+++ b/apps/api/src/modules/messaging/application/tests/get-messages.handler.spec.ts
@@ -0,0 +1,71 @@
+import { GetMessagesHandler } from '../queries/get-messages/get-messages.handler';
+import { GetMessagesQuery } from '../queries/get-messages/get-messages.query';
+
+describe('GetMessagesHandler', () => {
+  let handler: GetMessagesHandler;
+  let mockConversationRepo: {
+    findById: ReturnType<typeof vi.fn>;
+  };
+  let mockMessageRepo: {
+    findByConversationId: ReturnType<typeof vi.fn>;
+  };
+
+  const conversation = {
+    id: 'conv-1',
+    participants: [
+      { userId: 'user-1' },
+      { userId: 'user-2' },
+    ],
+  };
+
+  const messages = [
+    {
+      id: 'msg-1',
+      conversationId: 'conv-1',
+      senderId: 'user-1',
+      type: 'TEXT',
+      content: 'Hello!',
+      metadata: null,
+      editedAt: null,
+      deletedAt: null,
+      createdAt: new Date(),
+    },
+  ];
+
+  beforeEach(() => {
+    mockConversationRepo = {
+      findById: vi.fn().mockResolvedValue(conversation),
+    };
+    mockMessageRepo = {
+      findByConversationId: vi.fn().mockResolvedValue(messages),
+    };
+
+    handler = new GetMessagesHandler(
+      mockConversationRepo as any,
+      mockMessageRepo as any,
+    );
+  });
+
+  it('returns messages for a conversation', async () => {
+    const query = new GetMessagesQuery('conv-1', 'user-1', 50);
+
+    const result = await handler.execute(query);
+
+    expect(result).toHaveLength(1);
+    expect(mockMessageRepo.findByConversationId).toHaveBeenCalledWith('conv-1', 50, undefined);
+  });
+
+  it('throws NotFoundException when conversation does not exist', async () => {
+    mockConversationRepo.findById.mockResolvedValue(null);
+
+    const query = new GetMessagesQuery('conv-999', 'user-1');
+
+    await expect(handler.execute(query)).rejects.toThrow();
+  });
+
+  it('throws ForbiddenException when user is not a participant', async () => {
+    const query = new GetMessagesQuery('conv-1', 'user-3');
+
+    await expect(handler.execute(query)).rejects.toThrow('Bạn không phải là thành viên của hội thoại này');
+  });
+});
--- a/apps/api/src/modules/messaging/application/tests/mark-read.handler.spec.ts
+++ b/apps/api/src/modules/messaging/application/tests/mark-read.handler.spec.ts
@@ -0,0 +1,55 @@
+import { MarkConversationReadCommand } from '../commands/mark-read/mark-read.command';
+import { MarkConversationReadHandler } from '../commands/mark-read/mark-read.handler';
+
+describe('MarkConversationReadHandler', () => {
+  let handler: MarkConversationReadHandler;
+  let mockConversationRepo: {
+    findById: ReturnType<typeof vi.fn>;
+    resetUnreadCount: ReturnType<typeof vi.fn>;
+  };
+  let mockLogger: { log: ReturnType<typeof vi.fn>; warn: ReturnType<typeof vi.fn>; error: ReturnType<typeof vi.fn> };
+
+  const conversation = {
+    id: 'conv-1',
+    status: 'ACTIVE' as const,
+    participants: [
+      { id: 'p-1', conversationId: 'conv-1', userId: 'user-1', unreadCount: 3, lastReadAt: null, joinedAt: new Date() },
+      { id: 'p-2', conversationId: 'conv-1', userId: 'user-2', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+    ],
+  };
+
+  beforeEach(() => {
+    mockConversationRepo = {
+      findById: vi.fn().mockResolvedValue(conversation),
+      resetUnreadCount: vi.fn().mockResolvedValue(undefined),
+    };
+    mockLogger = { log: vi.fn(), warn: vi.fn(), error: vi.fn() };
+
+    handler = new MarkConversationReadHandler(
+      mockConversationRepo as any,
+      mockLogger as any,
+    );
+  });
+
+  it('marks conversation as read for the user', async () => {
+    const command = new MarkConversationReadCommand('conv-1', 'user-1');
+
+    await handler.execute(command);
+
+    expect(mockConversationRepo.resetUnreadCount).toHaveBeenCalledWith('conv-1', 'user-1');
+  });
+
+  it('throws NotFoundException when conversation does not exist', async () => {
+    mockConversationRepo.findById.mockResolvedValue(null);
+
+    const command = new MarkConversationReadCommand('conv-999', 'user-1');
+
+    await expect(handler.execute(command)).rejects.toThrow();
+  });
+
+  it('throws ForbiddenException when user is not a participant', async () => {
+    const command = new MarkConversationReadCommand('conv-1', 'user-3');
+
+    await expect(handler.execute(command)).rejects.toThrow('Bạn không phải là thành viên của hội thoại này');
+  });
+});
--- a/apps/api/src/modules/messaging/application/tests/send-message.handler.spec.ts
+++ b/apps/api/src/modules/messaging/application/tests/send-message.handler.spec.ts
@@ -0,0 +1,113 @@
+import { SendMessageCommand } from '../commands/send-message/send-message.command';
+import { SendMessageHandler } from '../commands/send-message/send-message.handler';
+
+describe('SendMessageHandler', () => {
+  let handler: SendMessageHandler;
+  let mockConversationRepo: {
+    findById: ReturnType<typeof vi.fn>;
+    updateLastMessage: ReturnType<typeof vi.fn>;
+    incrementUnreadCount: ReturnType<typeof vi.fn>;
+  };
+  let mockMessageRepo: {
+    create: ReturnType<typeof vi.fn>;
+  };
+  let mockEventBus: { publish: ReturnType<typeof vi.fn> };
+  let mockLogger: { log: ReturnType<typeof vi.fn>; warn: ReturnType<typeof vi.fn>; error: ReturnType<typeof vi.fn> };
+
+  const conversation = {
+    id: 'conv-1',
+    status: 'ACTIVE' as const,
+    participants: [
+      { id: 'p-1', conversationId: 'conv-1', userId: 'user-1', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+      { id: 'p-2', conversationId: 'conv-1', userId: 'user-2', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+    ],
+  };
+
+  const messageEntity = {
+    id: 'msg-1',
+    conversationId: 'conv-1',
+    senderId: 'user-1',
+    type: 'TEXT' as const,
+    content: 'Hello!',
+    metadata: null,
+    editedAt: null,
+    deletedAt: null,
+    createdAt: new Date(),
+  };
+
+  beforeEach(() => {
+    mockConversationRepo = {
+      findById: vi.fn().mockResolvedValue(conversation),
+      updateLastMessage: vi.fn().mockResolvedValue(undefined),
+      incrementUnreadCount: vi.fn().mockResolvedValue(undefined),
+    };
+    mockMessageRepo = {
+      create: vi.fn().mockResolvedValue(messageEntity),
+    };
+    mockEventBus = { publish: vi.fn() };
+    mockLogger = { log: vi.fn(), warn: vi.fn(), error: vi.fn() };
+
+    handler = new SendMessageHandler(
+      mockConversationRepo as any,
+      mockMessageRepo as any,
+      mockEventBus as any,
+      mockLogger as any,
+    );
+  });
+
+  it('sends a message successfully', async () => {
+    const command = new SendMessageCommand('conv-1', 'user-1', 'Hello!');
+
+    const result = await handler.execute(command);
+
+    expect(result.id).toBe('msg-1');
+    expect(mockMessageRepo.create).toHaveBeenCalledWith({
+      conversationId: 'conv-1',
+      senderId: 'user-1',
+      type: 'TEXT',
+      content: 'Hello!',
+      metadata: undefined,
+    });
+    expect(mockConversationRepo.updateLastMessage).toHaveBeenCalled();
+    expect(mockConversationRepo.incrementUnreadCount).toHaveBeenCalledWith('conv-1', 'user-1');
+    expect(mockEventBus.publish).toHaveBeenCalled();
+  });
+
+  it('throws NotFoundException when conversation does not exist', async () => {
+    mockConversationRepo.findById.mockResolvedValue(null);
+
+    const command = new SendMessageCommand('conv-999', 'user-1', 'Hello!');
+
+    await expect(handler.execute(command)).rejects.toThrow();
+  });
+
+  it('throws ForbiddenException when user is not a participant', async () => {
+    const command = new SendMessageCommand('conv-1', 'user-3', 'Hello!');
+
+    await expect(handler.execute(command)).rejects.toThrow('Bạn không phải là thành viên của hội thoại này');
+  });
+
+  it('throws ValidationException when conversation is closed', async () => {
+    mockConversationRepo.findById.mockResolvedValue({ ...conversation, status: 'CLOSED' });
+
+    const command = new SendMessageCommand('conv-1', 'user-1', 'Hello!');
+
+    await expect(handler.execute(command)).rejects.toThrow('Hội thoại đã đóng');
+  });
+
+  it('publishes MessageSentEvent after successful send', async () => {
+    const command = new SendMessageCommand('conv-1', 'user-1', 'Hello!');
+
+    await handler.execute(command);
+
+    expect(mockEventBus.publish).toHaveBeenCalledWith(
+      expect.objectContaining({
+        eventName: 'message.sent',
+        aggregateId: 'msg-1',
+        conversationId: 'conv-1',
+        senderId: 'user-1',
+        content: 'Hello!',
+      }),
+    );
+  });
+});
--- a/apps/api/src/modules/messaging/application/commands/create-conversation/create-conversation.command.ts
+++ b/apps/api/src/modules/messaging/application/commands/create-conversation/create-conversation.command.ts
@@ -0,0 +1,9 @@
+export class CreateConversationCommand {
+  constructor(
+    public readonly initiatorUserId: string,
+    public readonly participantUserId: string,
+    public readonly listingId?: string,
+    public readonly subject?: string,
+    public readonly initialMessage?: string,
+  ) {}
+}
--- a/apps/api/src/modules/messaging/application/commands/create-conversation/create-conversation.handler.ts
+++ b/apps/api/src/modules/messaging/application/commands/create-conversation/create-conversation.handler.ts
@@ -0,0 +1,94 @@
+import { Inject, InternalServerErrorException } from '@nestjs/common';
+import { CommandHandler, type ICommandHandler } from '@nestjs/cqrs';
+import { DomainException, ValidationException, type EventBusService, type LoggerService } from '@modules/shared';
+import type { ConversationEntity } from '../../../domain/entities/conversation.entity';
+import { MessageSentEvent } from '../../../domain/events/message-sent.event';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../../domain/repositories/conversation.repository';
+import {
+  MESSAGE_REPOSITORY,
+  type IMessageRepository,
+} from '../../../domain/repositories/message.repository';
+import { CreateConversationCommand } from './create-conversation.command';
+
+@CommandHandler(CreateConversationCommand)
+export class CreateConversationHandler implements ICommandHandler<CreateConversationCommand> {
+  constructor(
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+    @Inject(MESSAGE_REPOSITORY)
+    private readonly messageRepo: IMessageRepository,
+    private readonly eventBus: EventBusService,
+    private readonly logger: LoggerService,
+  ) {}
+
+  async execute(command: CreateConversationCommand): Promise<ConversationEntity> {
+    try {
+      const { initiatorUserId, participantUserId, listingId, subject, initialMessage } = command;
+
+      if (initiatorUserId === participantUserId) {
+        throw new ValidationException('Không thể tạo hội thoại với chính mình');
+      }
+
+      // Check for existing conversation between these users for the same listing
+      const userIds = [initiatorUserId, participantUserId];
+      const existing = await this.conversationRepo.findExistingBetweenUsers(userIds, listingId);
+      if (existing) {
+        // If there's an initial message, send it in the existing conversation
+        if (initialMessage) {
+          const message = await this.messageRepo.create({
+            conversationId: existing.id,
+            senderId: initiatorUserId,
+            type: 'TEXT',
+            content: initialMessage,
+          });
+          await this.conversationRepo.updateLastMessage(existing.id, initialMessage, message.createdAt);
+          await this.conversationRepo.incrementUnreadCount(existing.id, initiatorUserId);
+          this.eventBus.publish(
+            new MessageSentEvent(message.id, existing.id, initiatorUserId, 'TEXT', initialMessage),
+          );
+        }
+        return existing;
+      }
+
+      // Create new conversation
+      const conversation = await this.conversationRepo.create({
+        listingId,
+        subject,
+        participantUserIds: userIds,
+      });
+
+      // Send initial message if provided
+      if (initialMessage) {
+        const message = await this.messageRepo.create({
+          conversationId: conversation.id,
+          senderId: initiatorUserId,
+          type: 'TEXT',
+          content: initialMessage,
+        });
+        await this.conversationRepo.updateLastMessage(conversation.id, initialMessage, message.createdAt);
+        await this.conversationRepo.incrementUnreadCount(conversation.id, initiatorUserId);
+        this.eventBus.publish(
+          new MessageSentEvent(message.id, conversation.id, initiatorUserId, 'TEXT', initialMessage),
+        );
+      }
+
+      this.logger.log(
+        `Conversation created: ${conversation.id} between [${userIds.join(', ')}]`,
+        'CreateConversationHandler',
+      );
+
+      return conversation;
+    } catch (error) {
+      if (error instanceof DomainException) throw error;
+      this.logger.error(
+        `Failed to create conversation: ${error instanceof Error ? error.message : error}`,
+        error instanceof Error ? error.stack : undefined,
+        this.constructor.name,
+      );
+      throw new InternalServerErrorException('Không thể tạo hội thoại');
+    }
+  }
+}
--- a/apps/api/src/modules/messaging/application/commands/mark-read/mark-read.command.ts
+++ b/apps/api/src/modules/messaging/application/commands/mark-read/mark-read.command.ts
@@ -0,0 +1,6 @@
+export class MarkConversationReadCommand {
+  constructor(
+    public readonly conversationId: string,
+    public readonly userId: string,
+  ) {}
+}
--- a/apps/api/src/modules/messaging/application/commands/mark-read/mark-read.handler.ts
+++ b/apps/api/src/modules/messaging/application/commands/mark-read/mark-read.handler.ts
@@ -0,0 +1,43 @@
+import { Inject, InternalServerErrorException } from '@nestjs/common';
+import { CommandHandler, type ICommandHandler } from '@nestjs/cqrs';
+import { DomainException, ForbiddenException, NotFoundException, type LoggerService } from '@modules/shared';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../../domain/repositories/conversation.repository';
+import { MarkConversationReadCommand } from './mark-read.command';
+
+@CommandHandler(MarkConversationReadCommand)
+export class MarkConversationReadHandler implements ICommandHandler<MarkConversationReadCommand> {
+  constructor(
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+    private readonly logger: LoggerService,
+  ) {}
+
+  async execute(command: MarkConversationReadCommand): Promise<void> {
+    try {
+      const { conversationId, userId } = command;
+
+      const conversation = await this.conversationRepo.findById(conversationId);
+      if (!conversation) {
+        throw new NotFoundException('Conversation', conversationId);
+      }
+
+      const isParticipant = conversation.participants.some((p) => p.userId === userId);
+      if (!isParticipant) {
+        throw new ForbiddenException('Bạn không phải là thành viên của hội thoại này');
+      }
+
+      await this.conversationRepo.resetUnreadCount(conversationId, userId);
+    } catch (error) {
+      if (error instanceof DomainException) throw error;
+      this.logger.error(
+        `Failed to mark conversation read: ${error instanceof Error ? error.message : error}`,
+        error instanceof Error ? error.stack : undefined,
+        this.constructor.name,
+      );
+      throw new InternalServerErrorException('Không thể đánh dấu đã đọc');
+    }
+  }
+}
--- a/apps/api/src/modules/messaging/application/commands/send-message/send-message.command.ts
+++ b/apps/api/src/modules/messaging/application/commands/send-message/send-message.command.ts
@@ -0,0 +1,11 @@
+import type { MessageType } from '../../../domain/value-objects/message-type.vo';
+
+export class SendMessageCommand {
+  constructor(
+    public readonly conversationId: string,
+    public readonly senderId: string,
+    public readonly content: string,
+    public readonly type: MessageType = 'TEXT',
+    public readonly metadata?: Record<string, unknown>,
+  ) {}
+}
--- a/apps/api/src/modules/messaging/application/commands/send-message/send-message.handler.ts
+++ b/apps/api/src/modules/messaging/application/commands/send-message/send-message.handler.ts
@@ -0,0 +1,77 @@
+import { Inject, InternalServerErrorException } from '@nestjs/common';
+import { CommandHandler, type ICommandHandler } from '@nestjs/cqrs';
+import { DomainException, ForbiddenException, NotFoundException, ValidationException, type EventBusService, type LoggerService } from '@modules/shared';
+import type { MessageEntity } from '../../../domain/entities/message.entity';
+import { MessageSentEvent } from '../../../domain/events/message-sent.event';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../../domain/repositories/conversation.repository';
+import {
+  MESSAGE_REPOSITORY,
+  type IMessageRepository,
+} from '../../../domain/repositories/message.repository';
+import { SendMessageCommand } from './send-message.command';
+
+@CommandHandler(SendMessageCommand)
+export class SendMessageHandler implements ICommandHandler<SendMessageCommand> {
+  constructor(
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+    @Inject(MESSAGE_REPOSITORY)
+    private readonly messageRepo: IMessageRepository,
+    private readonly eventBus: EventBusService,
+    private readonly logger: LoggerService,
+  ) {}
+
+  async execute(command: SendMessageCommand): Promise<MessageEntity> {
+    try {
+      const { conversationId, senderId, content, type, metadata } = command;
+
+      // Verify conversation exists and sender is a participant
+      const conversation = await this.conversationRepo.findById(conversationId);
+      if (!conversation) {
+        throw new NotFoundException('Conversation', conversationId);
+      }
+
+      const isParticipant = conversation.participants.some((p) => p.userId === senderId);
+      if (!isParticipant) {
+        throw new ForbiddenException('Bạn không phải là thành viên của hội thoại này');
+      }
+
+      if (conversation.status !== 'ACTIVE') {
+        throw new ValidationException('Hội thoại đã đóng');
+      }
+
+      // Create message
+      const message = await this.messageRepo.create({
+        conversationId,
+        senderId,
+        type,
+        content,
+        metadata,
+      });
+
+      // Update conversation last message
+      await this.conversationRepo.updateLastMessage(conversationId, content, message.createdAt);
+
+      // Increment unread count for other participants
+      await this.conversationRepo.incrementUnreadCount(conversationId, senderId);
+
+      // Publish domain event
+      this.eventBus.publish(
+        new MessageSentEvent(message.id, conversationId, senderId, type, content),
+      );
+
+      return message;
+    } catch (error) {
+      if (error instanceof DomainException) throw error;
+      this.logger.error(
+        `Failed to send message: ${error instanceof Error ? error.message : error}`,
+        error instanceof Error ? error.stack : undefined,
+        this.constructor.name,
+      );
+      throw new InternalServerErrorException('Không thể gửi tin nhắn');
+    }
+  }
+}
--- a/apps/api/src/modules/messaging/application/queries/get-conversations/get-conversations.handler.ts
+++ b/apps/api/src/modules/messaging/application/queries/get-conversations/get-conversations.handler.ts
@@ -0,0 +1,24 @@
+import { Inject } from '@nestjs/common';
+import { type IQueryHandler, QueryHandler } from '@nestjs/cqrs';
+import type { ConversationEntity } from '../../../domain/entities/conversation.entity';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../../domain/repositories/conversation.repository';
+import { GetConversationsQuery } from './get-conversations.query';
+
+@QueryHandler(GetConversationsQuery)
+export class GetConversationsHandler implements IQueryHandler<GetConversationsQuery> {
+  constructor(
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+  ) {}
+
+  async execute(query: GetConversationsQuery): Promise<{ conversations: ConversationEntity[]; total: number }> {
+    const [conversations, total] = await Promise.all([
+      this.conversationRepo.findByUserId(query.userId, query.limit, query.offset),
+      this.conversationRepo.countByUserId(query.userId),
+    ]);
+    return { conversations, total };
+  }
+}
--- a/apps/api/src/modules/messaging/application/queries/get-conversations/get-conversations.query.ts
+++ b/apps/api/src/modules/messaging/application/queries/get-conversations/get-conversations.query.ts
@@ -0,0 +1,7 @@
+export class GetConversationsQuery {
+  constructor(
+    public readonly userId: string,
+    public readonly limit: number = 20,
+    public readonly offset: number = 0,
+  ) {}
+}
--- a/apps/api/src/modules/messaging/application/queries/get-messages/get-messages.handler.ts
+++ b/apps/api/src/modules/messaging/application/queries/get-messages/get-messages.handler.ts
@@ -0,0 +1,38 @@
+import { Inject } from '@nestjs/common';
+import { type IQueryHandler, QueryHandler } from '@nestjs/cqrs';
+import { ForbiddenException, NotFoundException } from '@modules/shared';
+import type { MessageEntity } from '../../../domain/entities/message.entity';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../../domain/repositories/conversation.repository';
+import {
+  MESSAGE_REPOSITORY,
+  type IMessageRepository,
+} from '../../../domain/repositories/message.repository';
+import { GetMessagesQuery } from './get-messages.query';
+
+@QueryHandler(GetMessagesQuery)
+export class GetMessagesHandler implements IQueryHandler<GetMessagesQuery> {
+  constructor(
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+    @Inject(MESSAGE_REPOSITORY)
+    private readonly messageRepo: IMessageRepository,
+  ) {}
+
+  async execute(query: GetMessagesQuery): Promise<MessageEntity[]> {
+    // Verify access
+    const conversation = await this.conversationRepo.findById(query.conversationId);
+    if (!conversation) {
+      throw new NotFoundException('Conversation', query.conversationId);
+    }
+
+    const isParticipant = conversation.participants.some((p) => p.userId === query.userId);
+    if (!isParticipant) {
+      throw new ForbiddenException('Bạn không phải là thành viên của hội thoại này');
+    }
+
+    return this.messageRepo.findByConversationId(query.conversationId, query.limit, query.before);
+  }
+}
--- a/apps/api/src/modules/messaging/application/queries/get-messages/get-messages.query.ts
+++ b/apps/api/src/modules/messaging/application/queries/get-messages/get-messages.query.ts
@@ -0,0 +1,8 @@
+export class GetMessagesQuery {
+  constructor(
+    public readonly conversationId: string,
+    public readonly userId: string,
+    public readonly limit: number = 50,
+    public readonly before?: string,
+  ) {}
+}
--- a/apps/api/src/modules/messaging/domain/tests/messaging-domain.spec.ts
+++ b/apps/api/src/modules/messaging/domain/tests/messaging-domain.spec.ts
@@ -0,0 +1,18 @@
+import { MessageSentEvent } from '../events/message-sent.event';
+
+describe('Messaging Domain', () => {
+  describe('MessageSentEvent', () => {
+    it('creates event with correct eventName', () => {
+      const event = new MessageSentEvent('msg-1', 'conv-1', 'user-1', 'TEXT', 'Hello!');
+
+      expect(event.eventName).toBe('message.sent');
+      expect(event.aggregateId).toBe('msg-1');
+      expect(event.messageId).toBe('msg-1');
+      expect(event.conversationId).toBe('conv-1');
+      expect(event.senderId).toBe('user-1');
+      expect(event.type).toBe('TEXT');
+      expect(event.content).toBe('Hello!');
+      expect(event.occurredAt).toBeInstanceOf(Date);
+    });
+  });
+});
--- a/apps/api/src/modules/messaging/domain/entities/conversation.entity.ts
+++ b/apps/api/src/modules/messaging/domain/entities/conversation.entity.ts
@@ -0,0 +1,22 @@
+import type { ConversationStatus } from '../value-objects/conversation-status.vo';
+
+export interface ConversationParticipantEntity {
+  id: string;
+  conversationId: string;
+  userId: string;
+  unreadCount: number;
+  lastReadAt: Date | null;
+  joinedAt: Date;
+}
+
+export interface ConversationEntity {
+  id: string;
+  listingId: string | null;
+  subject: string | null;
+  status: ConversationStatus;
+  lastMessage: string | null;
+  lastMessageAt: Date | null;
+  createdAt: Date;
+  updatedAt: Date;
+  participants: ConversationParticipantEntity[];
+}
--- a/apps/api/src/modules/messaging/domain/entities/message.entity.ts
+++ b/apps/api/src/modules/messaging/domain/entities/message.entity.ts
@@ -0,0 +1,13 @@
+import type { MessageType } from '../value-objects/message-type.vo';
+
+export interface MessageEntity {
+  id: string;
+  conversationId: string;
+  senderId: string;
+  type: MessageType;
+  content: string;
+  metadata: Record<string, unknown> | null;
+  editedAt: Date | null;
+  deletedAt: Date | null;
+  createdAt: Date;
+}
--- a/apps/api/src/modules/messaging/domain/events/message-sent.event.ts
+++ b/apps/api/src/modules/messaging/domain/events/message-sent.event.ts
@@ -0,0 +1,19 @@
+import { type DomainEvent } from '@modules/shared';
+import type { MessageType } from '../value-objects/message-type.vo';
+
+export class MessageSentEvent implements DomainEvent {
+  readonly eventName = 'message.sent';
+  readonly occurredAt = new Date();
+
+  constructor(
+    public readonly aggregateId: string,
+    public readonly conversationId: string,
+    public readonly senderId: string,
+    public readonly type: MessageType,
+    public readonly content: string,
+  ) {}
+
+  get messageId(): string {
+    return this.aggregateId;
+  }
+}
--- a/apps/api/src/modules/messaging/domain/index.ts
+++ b/apps/api/src/modules/messaging/domain/index.ts
@@ -0,0 +1,15 @@
+export type { ConversationEntity, ConversationParticipantEntity } from './entities/conversation.entity';
+export type { MessageEntity } from './entities/message.entity';
+export { MessageSentEvent } from './events/message-sent.event';
+export {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+  type CreateConversationDto,
+} from './repositories/conversation.repository';
+export {
+  MESSAGE_REPOSITORY,
+  type IMessageRepository,
+  type CreateMessageDto,
+} from './repositories/message.repository';
+export type { ConversationStatus } from './value-objects/conversation-status.vo';
+export { type MessageType, ALL_MESSAGE_TYPES } from './value-objects/message-type.vo';
--- a/apps/api/src/modules/messaging/domain/repositories/conversation.repository.ts
+++ b/apps/api/src/modules/messaging/domain/repositories/conversation.repository.ts
@@ -0,0 +1,22 @@
+import type { ConversationEntity } from '../entities/conversation.entity';
+import type { ConversationStatus } from '../value-objects/conversation-status.vo';
+
+export const CONVERSATION_REPOSITORY = Symbol('CONVERSATION_REPOSITORY');
+
+export interface CreateConversationDto {
+  listingId?: string;
+  subject?: string;
+  participantUserIds: string[];
+}
+
+export interface IConversationRepository {
+  create(dto: CreateConversationDto): Promise<ConversationEntity>;
+  findById(id: string): Promise<ConversationEntity | null>;
+  findByUserId(userId: string, limit?: number, offset?: number): Promise<ConversationEntity[]>;
+  findExistingBetweenUsers(userIds: string[], listingId?: string): Promise<ConversationEntity | null>;
+  updateStatus(id: string, status: ConversationStatus): Promise<void>;
+  updateLastMessage(id: string, content: string, sentAt: Date): Promise<void>;
+  incrementUnreadCount(conversationId: string, excludeUserId: string): Promise<void>;
+  resetUnreadCount(conversationId: string, userId: string): Promise<void>;
+  countByUserId(userId: string): Promise<number>;
+}
--- a/apps/api/src/modules/messaging/domain/repositories/message.repository.ts
+++ b/apps/api/src/modules/messaging/domain/repositories/message.repository.ts
@@ -0,0 +1,19 @@
+import type { MessageEntity } from '../entities/message.entity';
+import type { MessageType } from '../value-objects/message-type.vo';
+
+export const MESSAGE_REPOSITORY = Symbol('MESSAGE_REPOSITORY');
+
+export interface CreateMessageDto {
+  conversationId: string;
+  senderId: string;
+  type: MessageType;
+  content: string;
+  metadata?: Record<string, unknown>;
+}
+
+export interface IMessageRepository {
+  create(dto: CreateMessageDto): Promise<MessageEntity>;
+  findByConversationId(conversationId: string, limit?: number, before?: string): Promise<MessageEntity[]>;
+  findById(id: string): Promise<MessageEntity | null>;
+  softDelete(id: string, senderId: string): Promise<void>;
+}
--- a/apps/api/src/modules/messaging/domain/value-objects/conversation-status.vo.ts
+++ b/apps/api/src/modules/messaging/domain/value-objects/conversation-status.vo.ts
@@ -0,0 +1 @@
+export type ConversationStatus = 'ACTIVE' | 'ARCHIVED' | 'CLOSED';
--- a/apps/api/src/modules/messaging/domain/value-objects/message-type.vo.ts
+++ b/apps/api/src/modules/messaging/domain/value-objects/message-type.vo.ts
@@ -0,0 +1,3 @@
+export type MessageType = 'TEXT' | 'IMAGE' | 'FILE' | 'SYSTEM';
+
+export const ALL_MESSAGE_TYPES: MessageType[] = ['TEXT', 'IMAGE', 'FILE', 'SYSTEM'];
--- a/apps/api/src/modules/messaging/index.ts
+++ b/apps/api/src/modules/messaging/index.ts
@@ -0,0 +1,4 @@
+export { MessagingModule } from './messaging.module';
+export { MessagingGateway } from './presentation/gateways/messaging.gateway';
+export { CreateConversationCommand } from './application/commands/create-conversation/create-conversation.command';
+export { SendMessageCommand } from './application/commands/send-message/send-message.command';
--- a/apps/api/src/modules/messaging/infrastructure/tests/prisma-conversation.repository.spec.ts
+++ b/apps/api/src/modules/messaging/infrastructure/tests/prisma-conversation.repository.spec.ts
@@ -0,0 +1,134 @@
+import { PrismaConversationRepository } from '../repositories/prisma-conversation.repository';
+
+describe('PrismaConversationRepository', () => {
+  let repository: PrismaConversationRepository;
+  let mockPrisma: {
+    conversation: {
+      create: ReturnType<typeof vi.fn>;
+      findUnique: ReturnType<typeof vi.fn>;
+      findMany: ReturnType<typeof vi.fn>;
+      findFirst: ReturnType<typeof vi.fn>;
+      update: ReturnType<typeof vi.fn>;
+      count: ReturnType<typeof vi.fn>;
+    };
+    conversationParticipant: {
+      updateMany: ReturnType<typeof vi.fn>;
+    };
+  };
+
+  const mockConversation = {
+    id: 'conv-1',
+    listingId: 'listing-1',
+    subject: null,
+    status: 'ACTIVE',
+    lastMessage: null,
+    lastMessageAt: null,
+    createdAt: new Date(),
+    updatedAt: new Date(),
+    participants: [
+      { id: 'p-1', conversationId: 'conv-1', userId: 'user-1', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+      { id: 'p-2', conversationId: 'conv-1', userId: 'user-2', unreadCount: 0, lastReadAt: null, joinedAt: new Date() },
+    ],
+  };
+
+  beforeEach(() => {
+    mockPrisma = {
+      conversation: {
+        create: vi.fn().mockResolvedValue(mockConversation),
+        findUnique: vi.fn().mockResolvedValue(mockConversation),
+        findMany: vi.fn().mockResolvedValue([mockConversation]),
+        findFirst: vi.fn().mockResolvedValue(null),
+        update: vi.fn().mockResolvedValue(mockConversation),
+        count: vi.fn().mockResolvedValue(1),
+      },
+      conversationParticipant: {
+        updateMany: vi.fn().mockResolvedValue({ count: 1 }),
+      },
+    };
+    repository = new PrismaConversationRepository(mockPrisma as any);
+  });
+
+  it('creates a conversation with participants', async () => {
+    const result = await repository.create({
+      listingId: 'listing-1',
+      participantUserIds: ['user-1', 'user-2'],
+    });
+
+    expect(mockPrisma.conversation.create).toHaveBeenCalledWith({
+      data: {
+        listingId: 'listing-1',
+        subject: null,
+        participants: {
+          create: [{ userId: 'user-1' }, { userId: 'user-2' }],
+        },
+      },
+      include: { participants: true },
+    });
+    expect(result.id).toBe('conv-1');
+    expect(result.participants).toHaveLength(2);
+  });
+
+  it('finds conversation by id', async () => {
+    const result = await repository.findById('conv-1');
+
+    expect(mockPrisma.conversation.findUnique).toHaveBeenCalledWith({
+      where: { id: 'conv-1' },
+      include: { participants: true },
+    });
+    expect(result?.id).toBe('conv-1');
+  });
+
+  it('returns null when conversation not found', async () => {
+    mockPrisma.conversation.findUnique.mockResolvedValue(null);
+
+    const result = await repository.findById('conv-999');
+
+    expect(result).toBeNull();
+  });
+
+  it('finds conversations by user id', async () => {
+    const result = await repository.findByUserId('user-1', 20, 0);
+
+    expect(mockPrisma.conversation.findMany).toHaveBeenCalledWith(
+      expect.objectContaining({
+        where: { participants: { some: { userId: 'user-1' } } },
+        take: 20,
+        skip: 0,
+      }),
+    );
+    expect(result).toHaveLength(1);
+  });
+
+  it('updates conversation status', async () => {
+    await repository.updateStatus('conv-1', 'CLOSED');
+
+    expect(mockPrisma.conversation.update).toHaveBeenCalledWith({
+      where: { id: 'conv-1' },
+      data: { status: 'CLOSED' },
+    });
+  });
+
+  it('increments unread count for other participants', async () => {
+    await repository.incrementUnreadCount('conv-1', 'user-1');
+
+    expect(mockPrisma.conversationParticipant.updateMany).toHaveBeenCalledWith({
+      where: { conversationId: 'conv-1', userId: { not: 'user-1' } },
+      data: { unreadCount: { increment: 1 } },
+    });
+  });
+
+  it('resets unread count for a user', async () => {
+    await repository.resetUnreadCount('conv-1', 'user-1');
+
+    expect(mockPrisma.conversationParticipant.updateMany).toHaveBeenCalledWith({
+      where: { conversationId: 'conv-1', userId: 'user-1' },
+      data: { unreadCount: 0, lastReadAt: expect.any(Date) },
+    });
+  });
+
+  it('counts conversations by user id', async () => {
+    const count = await repository.countByUserId('user-1');
+
+    expect(count).toBe(1);
+  });
+});
--- a/apps/api/src/modules/messaging/infrastructure/tests/prisma-message.repository.spec.ts
+++ b/apps/api/src/modules/messaging/infrastructure/tests/prisma-message.repository.spec.ts
@@ -0,0 +1,88 @@
+import { PrismaMessageRepository } from '../repositories/prisma-message.repository';
+
+describe('PrismaMessageRepository', () => {
+  let repository: PrismaMessageRepository;
+  let mockPrisma: {
+    message: {
+      create: ReturnType<typeof vi.fn>;
+      findMany: ReturnType<typeof vi.fn>;
+      findUnique: ReturnType<typeof vi.fn>;
+      updateMany: ReturnType<typeof vi.fn>;
+    };
+  };
+
+  const mockMessage = {
+    id: 'msg-1',
+    conversationId: 'conv-1',
+    senderId: 'user-1',
+    type: 'TEXT',
+    content: 'Hello!',
+    metadata: null,
+    editedAt: null,
+    deletedAt: null,
+    createdAt: new Date(),
+  };
+
+  beforeEach(() => {
+    mockPrisma = {
+      message: {
+        create: vi.fn().mockResolvedValue(mockMessage),
+        findMany: vi.fn().mockResolvedValue([mockMessage]),
+        findUnique: vi.fn().mockResolvedValue(mockMessage),
+        updateMany: vi.fn().mockResolvedValue({ count: 1 }),
+      },
+    };
+    repository = new PrismaMessageRepository(mockPrisma as any);
+  });
+
+  it('creates a message', async () => {
+    const result = await repository.create({
+      conversationId: 'conv-1',
+      senderId: 'user-1',
+      type: 'TEXT',
+      content: 'Hello!',
+    });
+
+    expect(mockPrisma.message.create).toHaveBeenCalledWith({
+      data: {
+        conversationId: 'conv-1',
+        senderId: 'user-1',
+        type: 'TEXT',
+        content: 'Hello!',
+        metadata: undefined,
+      },
+    });
+    expect(result.id).toBe('msg-1');
+    expect(result.type).toBe('TEXT');
+  });
+
+  it('finds messages by conversation id', async () => {
+    const result = await repository.findByConversationId('conv-1', 50);
+
+    expect(result).toHaveLength(1);
+    expect(result[0]!.content).toBe('Hello!');
+  });
+
+  it('finds message by id', async () => {
+    const result = await repository.findById('msg-1');
+
+    expect(result?.id).toBe('msg-1');
+  });
+
+  it('returns null when message not found', async () => {
+    mockPrisma.message.findUnique.mockResolvedValue(null);
+
+    const result = await repository.findById('msg-999');
+
+    expect(result).toBeNull();
+  });
+
+  it('soft-deletes a message by sender only', async () => {
+    await repository.softDelete('msg-1', 'user-1');
+
+    expect(mockPrisma.message.updateMany).toHaveBeenCalledWith({
+      where: { id: 'msg-1', senderId: 'user-1' },
+      data: { deletedAt: expect.any(Date) },
+    });
+  });
+});
--- a/apps/api/src/modules/messaging/infrastructure/index.ts
+++ b/apps/api/src/modules/messaging/infrastructure/index.ts
@@ -0,0 +1,2 @@
+export { PrismaConversationRepository } from './repositories/prisma-conversation.repository';
+export { PrismaMessageRepository } from './repositories/prisma-message.repository';
--- a/apps/api/src/modules/messaging/infrastructure/repositories/prisma-conversation.repository.ts
+++ b/apps/api/src/modules/messaging/infrastructure/repositories/prisma-conversation.repository.ts
@@ -0,0 +1,141 @@
+import { Injectable } from '@nestjs/common';
+import { type PrismaService } from '@modules/shared';
+import type { ConversationEntity, ConversationParticipantEntity } from '../../domain/entities/conversation.entity';
+import type {
+  IConversationRepository,
+  CreateConversationDto,
+} from '../../domain/repositories/conversation.repository';
+import type { ConversationStatus } from '../../domain/value-objects/conversation-status.vo';
+
+@Injectable()
+export class PrismaConversationRepository implements IConversationRepository {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async create(dto: CreateConversationDto): Promise<ConversationEntity> {
+    const record = await this.prisma.conversation.create({
+      data: {
+        listingId: dto.listingId ?? null,
+        subject: dto.subject ?? null,
+        participants: {
+          create: dto.participantUserIds.map((userId) => ({ userId })),
+        },
+      },
+      include: { participants: true },
+    });
+    return this.toEntity(record);
+  }
+
+  async findById(id: string): Promise<ConversationEntity | null> {
+    const record = await this.prisma.conversation.findUnique({
+      where: { id },
+      include: { participants: true },
+    });
+    return record ? this.toEntity(record) : null;
+  }
+
+  async findByUserId(userId: string, limit = 20, offset = 0): Promise<ConversationEntity[]> {
+    const records = await this.prisma.conversation.findMany({
+      where: {
+        participants: { some: { userId } },
+      },
+      include: { participants: true },
+      orderBy: { lastMessageAt: { sort: 'desc', nulls: 'last' } },
+      take: limit,
+      skip: offset,
+    });
+    return records.map((r) => this.toEntity(r));
+  }
+
+  async findExistingBetweenUsers(
+    userIds: string[],
+    listingId?: string,
+  ): Promise<ConversationEntity | null> {
+    const record = await this.prisma.conversation.findFirst({
+      where: {
+        status: 'ACTIVE',
+        ...(listingId ? { listingId } : {}),
+        AND: userIds.map((userId) => ({
+          participants: { some: { userId } },
+        })),
+        participants: { every: { userId: { in: userIds } } },
+      },
+      include: { participants: true },
+    });
+    return record ? this.toEntity(record) : null;
+  }
+
+  async updateStatus(id: string, status: ConversationStatus): Promise<void> {
+    await this.prisma.conversation.update({
+      where: { id },
+      data: { status },
+    });
+  }
+
+  async updateLastMessage(id: string, content: string, sentAt: Date): Promise<void> {
+    await this.prisma.conversation.update({
+      where: { id },
+      data: {
+        lastMessage: content.length > 200 ? content.slice(0, 200) + '...' : content,
+        lastMessageAt: sentAt,
+      },
+    });
+  }
+
+  async incrementUnreadCount(conversationId: string, excludeUserId: string): Promise<void> {
+    await this.prisma.conversationParticipant.updateMany({
+      where: { conversationId, userId: { not: excludeUserId } },
+      data: { unreadCount: { increment: 1 } },
+    });
+  }
+
+  async resetUnreadCount(conversationId: string, userId: string): Promise<void> {
+    await this.prisma.conversationParticipant.updateMany({
+      where: { conversationId, userId },
+      data: { unreadCount: 0, lastReadAt: new Date() },
+    });
+  }
+
+  async countByUserId(userId: string): Promise<number> {
+    return this.prisma.conversation.count({
+      where: { participants: { some: { userId } } },
+    });
+  }
+
+  private toEntity(record: {
+    id: string;
+    listingId: string | null;
+    subject: string | null;
+    status: string;
+    lastMessage: string | null;
+    lastMessageAt: Date | null;
+    createdAt: Date;
+    updatedAt: Date;
+    participants: Array<{
+      id: string;
+      conversationId: string;
+      userId: string;
+      unreadCount: number;
+      lastReadAt: Date | null;
+      joinedAt: Date;
+    }>;
+  }): ConversationEntity {
+    return {
+      id: record.id,
+      listingId: record.listingId,
+      subject: record.subject,
+      status: record.status as ConversationStatus,
+      lastMessage: record.lastMessage,
+      lastMessageAt: record.lastMessageAt,
+      createdAt: record.createdAt,
+      updatedAt: record.updatedAt,
+      participants: record.participants.map((p): ConversationParticipantEntity => ({
+        id: p.id,
+        conversationId: p.conversationId,
+        userId: p.userId,
+        unreadCount: p.unreadCount,
+        lastReadAt: p.lastReadAt,
+        joinedAt: p.joinedAt,
+      })),
+    };
+  }
+}
--- a/apps/api/src/modules/messaging/infrastructure/repositories/prisma-message.repository.ts
+++ b/apps/api/src/modules/messaging/infrastructure/repositories/prisma-message.repository.ts
@@ -0,0 +1,80 @@
+import { Injectable } from '@nestjs/common';
+import { type Prisma } from '@prisma/client';
+import { type PrismaService } from '@modules/shared';
+import type { MessageEntity } from '../../domain/entities/message.entity';
+import type {
+  IMessageRepository,
+  CreateMessageDto,
+} from '../../domain/repositories/message.repository';
+import type { MessageType } from '../../domain/value-objects/message-type.vo';
+
+@Injectable()
+export class PrismaMessageRepository implements IMessageRepository {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async create(dto: CreateMessageDto): Promise<MessageEntity> {
+    const record = await this.prisma.message.create({
+      data: {
+        conversationId: dto.conversationId,
+        senderId: dto.senderId,
+        type: dto.type,
+        content: dto.content,
+        metadata: (dto.metadata ?? undefined) as Prisma.InputJsonValue | undefined,
+      },
+    });
+    return this.toEntity(record);
+  }
+
+  async findByConversationId(
+    conversationId: string,
+    limit = 50,
+    before?: string,
+  ): Promise<MessageEntity[]> {
+    const records = await this.prisma.message.findMany({
+      where: {
+        conversationId,
+        deletedAt: null,
+        ...(before ? { createdAt: { lt: (await this.prisma.message.findUnique({ where: { id: before } }))?.createdAt } } : {}),
+      },
+      orderBy: { createdAt: 'desc' },
+      take: limit,
+    });
+    return records.map((r) => this.toEntity(r));
+  }
+
+  async findById(id: string): Promise<MessageEntity | null> {
+    const record = await this.prisma.message.findUnique({ where: { id } });
+    return record ? this.toEntity(record) : null;
+  }
+
+  async softDelete(id: string, senderId: string): Promise<void> {
+    await this.prisma.message.updateMany({
+      where: { id, senderId },
+      data: { deletedAt: new Date() },
+    });
+  }
+
+  private toEntity(record: {
+    id: string;
+    conversationId: string;
+    senderId: string;
+    type: string;
+    content: string;
+    metadata: unknown;
+    editedAt: Date | null;
+    deletedAt: Date | null;
+    createdAt: Date;
+  }): MessageEntity {
+    return {
+      id: record.id,
+      conversationId: record.conversationId,
+      senderId: record.senderId,
+      type: record.type as MessageType,
+      content: record.content,
+      metadata: record.metadata as Record<string, unknown> | null,
+      editedAt: record.editedAt,
+      deletedAt: record.deletedAt,
+      createdAt: record.createdAt,
+    };
+  }
+}
--- a/apps/api/src/modules/messaging/messaging.module.ts
+++ b/apps/api/src/modules/messaging/messaging.module.ts
@@ -0,0 +1,44 @@
+import { Module } from '@nestjs/common';
+import { CqrsModule } from '@nestjs/cqrs';
+import { AuthModule } from '@modules/auth';
+import { CreateConversationHandler } from './application/commands/create-conversation/create-conversation.handler';
+import { MarkConversationReadHandler } from './application/commands/mark-read/mark-read.handler';
+import { SendMessageHandler } from './application/commands/send-message/send-message.handler';
+import { GetConversationsHandler } from './application/queries/get-conversations/get-conversations.handler';
+import { GetMessagesHandler } from './application/queries/get-messages/get-messages.handler';
+import { CONVERSATION_REPOSITORY } from './domain/repositories/conversation.repository';
+import { MESSAGE_REPOSITORY } from './domain/repositories/message.repository';
+import { PrismaConversationRepository } from './infrastructure/repositories/prisma-conversation.repository';
+import { PrismaMessageRepository } from './infrastructure/repositories/prisma-message.repository';
+import { MessagingController } from './presentation/controllers/messaging.controller';
+import { MessagingGateway } from './presentation/gateways/messaging.gateway';
+
+const CommandHandlers = [
+  CreateConversationHandler,
+  SendMessageHandler,
+  MarkConversationReadHandler,
+];
+
+const QueryHandlers = [
+  GetConversationsHandler,
+  GetMessagesHandler,
+];
+
+@Module({
+  imports: [CqrsModule, AuthModule],
+  controllers: [MessagingController],
+  providers: [
+    // Repositories
+    { provide: CONVERSATION_REPOSITORY, useClass: PrismaConversationRepository },
+    { provide: MESSAGE_REPOSITORY, useClass: PrismaMessageRepository },
+
+    // WebSocket Gateway
+    MessagingGateway,
+
+    // CQRS
+    ...CommandHandlers,
+    ...QueryHandlers,
+  ],
+  exports: [MessagingGateway],
+})
+export class MessagingModule {}
--- a/apps/api/src/modules/messaging/presentation/tests/messaging.controller.spec.ts
+++ b/apps/api/src/modules/messaging/presentation/tests/messaging.controller.spec.ts
@@ -0,0 +1,97 @@
+import { CreateConversationCommand } from '../../application/commands/create-conversation/create-conversation.command';
+import { MarkConversationReadCommand } from '../../application/commands/mark-read/mark-read.command';
+import { SendMessageCommand } from '../../application/commands/send-message/send-message.command';
+import { GetConversationsQuery } from '../../application/queries/get-conversations/get-conversations.query';
+import { GetMessagesQuery } from '../../application/queries/get-messages/get-messages.query';
+import { MessagingController } from '../controllers/messaging.controller';
+
+describe('MessagingController', () => {
+  let controller: MessagingController;
+  let mockCommandBus: { execute: ReturnType<typeof vi.fn> };
+  let mockQueryBus: { execute: ReturnType<typeof vi.fn> };
+  let mockMessageRepo: { softDelete: ReturnType<typeof vi.fn> };
+
+  const user = { sub: 'user-1', role: 'BUYER' };
+
+  beforeEach(() => {
+    mockCommandBus = { execute: vi.fn() };
+    mockQueryBus = { execute: vi.fn() };
+    mockMessageRepo = { softDelete: vi.fn() };
+
+    controller = new MessagingController(
+      mockCommandBus as any,
+      mockQueryBus as any,
+      mockMessageRepo as any,
+    );
+  });
+
+  describe('createConversation', () => {
+    it('dispatches CreateConversationCommand', async () => {
+      const dto = { participantUserId: 'user-2', listingId: 'listing-1', initialMessage: 'Hi' };
+      mockCommandBus.execute.mockResolvedValue({ id: 'conv-1' });
+
+      const result = await controller.createConversation(user as any, dto as any);
+
+      expect(mockCommandBus.execute).toHaveBeenCalledWith(
+        expect.any(CreateConversationCommand),
+      );
+      expect(result.id).toBe('conv-1');
+    });
+  });
+
+  describe('getConversations', () => {
+    it('dispatches GetConversationsQuery', async () => {
+      mockQueryBus.execute.mockResolvedValue({ conversations: [], total: 0 });
+
+      await controller.getConversations(user as any, 20, 0);
+
+      expect(mockQueryBus.execute).toHaveBeenCalledWith(
+        expect.any(GetConversationsQuery),
+      );
+    });
+  });
+
+  describe('getMessages', () => {
+    it('dispatches GetMessagesQuery', async () => {
+      mockQueryBus.execute.mockResolvedValue([]);
+
+      await controller.getMessages(user as any, 'conv-1', 50);
+
+      expect(mockQueryBus.execute).toHaveBeenCalledWith(
+        expect.any(GetMessagesQuery),
+      );
+    });
+  });
+
+  describe('sendMessage', () => {
+    it('dispatches SendMessageCommand', async () => {
+      const dto = { content: 'Hello!' };
+      mockCommandBus.execute.mockResolvedValue({ id: 'msg-1' });
+
+      const result = await controller.sendMessage(user as any, 'conv-1', dto as any);
+
+      expect(mockCommandBus.execute).toHaveBeenCalledWith(
+        expect.any(SendMessageCommand),
+      );
+      expect(result.id).toBe('msg-1');
+    });
+  });
+
+  describe('markAsRead', () => {
+    it('dispatches MarkConversationReadCommand', async () => {
+      await controller.markAsRead(user as any, 'conv-1');
+
+      expect(mockCommandBus.execute).toHaveBeenCalledWith(
+        expect.any(MarkConversationReadCommand),
+      );
+    });
+  });
+
+  describe('deleteMessage', () => {
+    it('calls messageRepo.softDelete with user id', async () => {
+      await controller.deleteMessage(user as any, 'msg-1');
+
+      expect(mockMessageRepo.softDelete).toHaveBeenCalledWith('msg-1', 'user-1');
+    });
+  });
+});
--- a/apps/api/src/modules/messaging/presentation/tests/messaging.gateway.spec.ts
+++ b/apps/api/src/modules/messaging/presentation/tests/messaging.gateway.spec.ts
@@ -0,0 +1,199 @@
+import { MessagingGateway } from '../gateways/messaging.gateway';
+
+describe('MessagingGateway', () => {
+  let gateway: MessagingGateway;
+  let mockTokenService: { verifyAccessToken: ReturnType<typeof vi.fn> };
+  let mockLogger: { log: ReturnType<typeof vi.fn>; warn: ReturnType<typeof vi.fn>; error: ReturnType<typeof vi.fn>; debug: ReturnType<typeof vi.fn> };
+  let mockCommandBus: { execute: ReturnType<typeof vi.fn> };
+  let mockConversationRepo: {
+    findByUserId: ReturnType<typeof vi.fn>;
+    findById: ReturnType<typeof vi.fn>;
+  };
+
+  beforeEach(() => {
+    mockTokenService = { verifyAccessToken: vi.fn() };
+    mockLogger = { log: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() };
+    mockCommandBus = { execute: vi.fn() };
+    mockConversationRepo = {
+      findByUserId: vi.fn().mockResolvedValue([]),
+      findById: vi.fn(),
+    };
+
+    gateway = new MessagingGateway(
+      mockTokenService as any,
+      mockLogger as any,
+      mockCommandBus as any,
+      mockConversationRepo as any,
+    );
+    gateway.server = {
+      to: vi.fn().mockReturnThis(),
+      emit: vi.fn(),
+    } as any;
+  });
+
+  describe('handleConnection', () => {
+    it('authenticates client and joins rooms', async () => {
+      mockTokenService.verifyAccessToken.mockReturnValue({ sub: 'user-1', role: 'BUYER' });
+      mockConversationRepo.findByUserId.mockResolvedValue([
+        { id: 'conv-1' },
+        { id: 'conv-2' },
+      ]);
+
+      const client = {
+        id: 'socket-1',
+        data: {},
+        handshake: { auth: { token: 'valid-token' }, headers: {}, query: {} },
+        join: vi.fn(),
+        emit: vi.fn(),
+        disconnect: vi.fn(),
+      };
+
+      await gateway.handleConnection(client as any);
+
+      expect(client.data['userId']).toBe('user-1');
+      expect(client.join).toHaveBeenCalledWith('user:user-1');
+      expect(client.join).toHaveBeenCalledWith('conversation:conv-1');
+      expect(client.join).toHaveBeenCalledWith('conversation:conv-2');
+    });
+
+    it('disconnects client with no token', async () => {
+      const client = {
+        id: 'socket-1',
+        data: {},
+        handshake: { auth: {}, headers: {}, query: {} },
+        join: vi.fn(),
+        emit: vi.fn(),
+        disconnect: vi.fn(),
+      };
+
+      mockTokenService.verifyAccessToken.mockReturnValue(null);
+
+      await gateway.handleConnection(client as any);
+
+      expect(client.disconnect).toHaveBeenCalledWith(true);
+    });
+
+    it('disconnects client with invalid token', async () => {
+      mockTokenService.verifyAccessToken.mockReturnValue(null);
+
+      const client = {
+        id: 'socket-1',
+        data: {},
+        handshake: { auth: { token: 'invalid' }, headers: {}, query: {} },
+        join: vi.fn(),
+        emit: vi.fn(),
+        disconnect: vi.fn(),
+      };
+
+      await gateway.handleConnection(client as any);
+
+      expect(client.disconnect).toHaveBeenCalledWith(true);
+    });
+  });
+
+  describe('handleDisconnect', () => {
+    it('cleans up socket tracking', () => {
+      // First connect
+      (gateway as any).userSockets.set('user-1', new Set(['socket-1']));
+
+      const client = {
+        id: 'socket-1',
+        data: { userId: 'user-1' },
+      };
+
+      gateway.handleDisconnect(client as any);
+
+      expect((gateway as any).userSockets.has('user-1')).toBe(false);
+    });
+  });
+
+  describe('handleMessageSent', () => {
+    it('emits message:new to conversation room', async () => {
+      const event = {
+        aggregateId: 'msg-1',
+        conversationId: 'conv-1',
+        senderId: 'user-1',
+        type: 'TEXT',
+        content: 'Hello!',
+        occurredAt: new Date(),
+      };
+
+      await gateway.handleMessageSent(event as any);
+
+      expect(gateway.server.to).toHaveBeenCalledWith('conversation:conv-1');
+    });
+  });
+
+  describe('handleSendMessage', () => {
+    it('sends message via command bus', async () => {
+      mockCommandBus.execute.mockResolvedValue({ id: 'msg-1' });
+
+      const client = {
+        data: { userId: 'user-1' },
+        emit: vi.fn(),
+      };
+
+      await gateway.handleSendMessage(
+        client as any,
+        { conversationId: 'conv-1', content: 'Hello!' },
+      );
+
+      expect(mockCommandBus.execute).toHaveBeenCalled();
+      expect(client.emit).toHaveBeenCalledWith('message:sent', {
+        messageId: 'msg-1',
+        conversationId: 'conv-1',
+      });
+    });
+
+    it('emits error when send fails', async () => {
+      mockCommandBus.execute.mockRejectedValue(new Error('Send failed'));
+
+      const client = {
+        data: { userId: 'user-1' },
+        emit: vi.fn(),
+      };
+
+      await gateway.handleSendMessage(
+        client as any,
+        { conversationId: 'conv-1', content: 'Hello!' },
+      );
+
+      expect(client.emit).toHaveBeenCalledWith('message:error', {
+        conversationId: 'conv-1',
+        error: 'Send failed',
+      });
+    });
+  });
+
+  describe('handleJoinConversation', () => {
+    it('joins room when user is participant', async () => {
+      mockConversationRepo.findById.mockResolvedValue({
+        participants: [{ userId: 'user-1' }],
+      });
+
+      const client = {
+        data: { userId: 'user-1' },
+        join: vi.fn(),
+      };
+
+      await gateway.handleJoinConversation(client as any, { conversationId: 'conv-1' });
+
+      expect(client.join).toHaveBeenCalledWith('conversation:conv-1');
+    });
+
+    it('does not join room when user is not participant', async () => {
+      mockConversationRepo.findById.mockResolvedValue({
+        participants: [{ userId: 'user-2' }],
+      });
+
+      const client = {
+        data: { userId: 'user-1' },
+        join: vi.fn(),
+      };
+
+      await gateway.handleJoinConversation(client as any, { conversationId: 'conv-1' });
+
+      expect(client.join).not.toHaveBeenCalled();
+    });
+  });
+});
--- a/apps/api/src/modules/messaging/presentation/controllers/messaging.controller.ts
+++ b/apps/api/src/modules/messaging/presentation/controllers/messaging.controller.ts
@@ -0,0 +1,188 @@
+import {
+  Controller,
+  Get,
+  Post,
+  Patch,
+  Delete,
+  Body,
+  Param,
+  Query,
+  Inject,
+  UseGuards,
+  HttpCode,
+  HttpStatus,
+} from '@nestjs/common';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports -- NestJS DI requires value imports
+import { CommandBus, QueryBus } from '@nestjs/cqrs';
+import { AuthGuard } from '@nestjs/passport';
+import { ApiTags, ApiOperation, ApiResponse, ApiBearerAuth, ApiQuery, ApiProperty } from '@nestjs/swagger';
+import { MessageType as PrismaMessageType } from '@prisma/client';
+import { IsString, IsOptional, IsEnum, MaxLength } from 'class-validator';
+import { CurrentUser, type JwtPayload } from '@modules/auth';
+import { CreateConversationCommand } from '../../application/commands/create-conversation/create-conversation.command';
+import { MarkConversationReadCommand } from '../../application/commands/mark-read/mark-read.command';
+import { SendMessageCommand } from '../../application/commands/send-message/send-message.command';
+import { GetConversationsQuery } from '../../application/queries/get-conversations/get-conversations.query';
+import { GetMessagesQuery } from '../../application/queries/get-messages/get-messages.query';
+import {
+  MESSAGE_REPOSITORY,
+  type IMessageRepository,
+} from '../../domain/repositories/message.repository';
+
+class CreateConversationDto {
+  @ApiProperty({ description: 'User ID of the other participant' })
+  @IsString()
+  participantUserId!: string;
+
+  @ApiProperty({ required: false, description: 'Associated listing ID' })
+  @IsString()
+  @IsOptional()
+  listingId?: string;
+
+  @ApiProperty({ required: false, description: 'Conversation subject' })
+  @IsString()
+  @IsOptional()
+  @MaxLength(200)
+  subject?: string;
+
+  @ApiProperty({ required: false, description: 'Initial message text' })
+  @IsString()
+  @IsOptional()
+  @MaxLength(5000)
+  initialMessage?: string;
+}
+
+class SendMessageDto {
+  @ApiProperty({ description: 'Message content' })
+  @IsString()
+  @MaxLength(5000)
+  content!: string;
+
+  @ApiProperty({ enum: PrismaMessageType, required: false, default: 'TEXT' })
+  @IsEnum(PrismaMessageType)
+  @IsOptional()
+  type?: PrismaMessageType;
+
+  @ApiProperty({ required: false, description: 'Additional metadata (e.g. file URL)' })
+  @IsOptional()
+  metadata?: Record<string, unknown>;
+}
+
+@ApiTags('messaging')
+@ApiBearerAuth('JWT')
+@Controller('messaging')
+@UseGuards(AuthGuard('jwt'))
+export class MessagingController {
+  constructor(
+    private readonly commandBus: CommandBus,
+    private readonly queryBus: QueryBus,
+    @Inject(MESSAGE_REPOSITORY)
+    private readonly messageRepo: IMessageRepository,
+  ) {}
+
+  @Post('conversations')
+  @ApiOperation({ summary: 'Create a conversation or return existing one' })
+  @ApiResponse({ status: 201, description: 'Conversation created' })
+  @ApiResponse({ status: 400, description: 'Cannot create conversation with yourself' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  async createConversation(
+    @CurrentUser() user: JwtPayload,
+    @Body() dto: CreateConversationDto,
+  ) {
+    return this.commandBus.execute(
+      new CreateConversationCommand(
+        user.sub,
+        dto.participantUserId,
+        dto.listingId,
+        dto.subject,
+        dto.initialMessage,
+      ),
+    );
+  }
+
+  @Get('conversations')
+  @ApiOperation({ summary: 'List user conversations' })
+  @ApiResponse({ status: 200, description: 'Conversations retrieved' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  @ApiQuery({ name: 'limit', required: false, type: Number })
+  @ApiQuery({ name: 'offset', required: false, type: Number })
+  async getConversations(
+    @CurrentUser() user: JwtPayload,
+    @Query('limit') limit?: number,
+    @Query('offset') offset?: number,
+  ) {
+    return this.queryBus.execute(
+      new GetConversationsQuery(user.sub, limit ?? 20, offset ?? 0),
+    );
+  }
+
+  @Get('conversations/:id/messages')
+  @ApiOperation({ summary: 'Get messages in a conversation' })
+  @ApiResponse({ status: 200, description: 'Messages retrieved' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  @ApiResponse({ status: 403, description: 'Not a participant' })
+  @ApiResponse({ status: 404, description: 'Conversation not found' })
+  @ApiQuery({ name: 'limit', required: false, type: Number })
+  @ApiQuery({ name: 'before', required: false, type: String, description: 'Cursor: message ID for pagination' })
+  async getMessages(
+    @CurrentUser() user: JwtPayload,
+    @Param('id') conversationId: string,
+    @Query('limit') limit?: number,
+    @Query('before') before?: string,
+  ) {
+    return this.queryBus.execute(
+      new GetMessagesQuery(conversationId, user.sub, limit ?? 50, before),
+    );
+  }
+
+  @Post('conversations/:id/messages')
+  @HttpCode(HttpStatus.CREATED)
+  @ApiOperation({ summary: 'Send a message in a conversation' })
+  @ApiResponse({ status: 201, description: 'Message sent' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  @ApiResponse({ status: 403, description: 'Not a participant' })
+  @ApiResponse({ status: 404, description: 'Conversation not found' })
+  async sendMessage(
+    @CurrentUser() user: JwtPayload,
+    @Param('id') conversationId: string,
+    @Body() dto: SendMessageDto,
+  ) {
+    return this.commandBus.execute(
+      new SendMessageCommand(
+        conversationId,
+        user.sub,
+        dto.content,
+        dto.type ?? 'TEXT',
+        dto.metadata,
+      ),
+    );
+  }
+
+  @Patch('conversations/:id/read')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  @ApiOperation({ summary: 'Mark a conversation as read' })
+  @ApiResponse({ status: 204, description: 'Conversation marked as read' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  @ApiResponse({ status: 403, description: 'Not a participant' })
+  @ApiResponse({ status: 404, description: 'Conversation not found' })
+  async markAsRead(
+    @CurrentUser() user: JwtPayload,
+    @Param('id') conversationId: string,
+  ) {
+    await this.commandBus.execute(
+      new MarkConversationReadCommand(conversationId, user.sub),
+    );
+  }
+
+  @Delete('conversations/:conversationId/messages/:messageId')
+  @HttpCode(HttpStatus.NO_CONTENT)
+  @ApiOperation({ summary: 'Soft-delete a message (sender only)' })
+  @ApiResponse({ status: 204, description: 'Message deleted' })
+  @ApiResponse({ status: 401, description: 'Unauthorized' })
+  async deleteMessage(
+    @CurrentUser() user: JwtPayload,
+    @Param('messageId') messageId: string,
+  ) {
+    await this.messageRepo.softDelete(messageId, user.sub);
+  }
+}
--- a/apps/api/src/modules/messaging/presentation/gateways/messaging.gateway.ts
+++ b/apps/api/src/modules/messaging/presentation/gateways/messaging.gateway.ts
@@ -0,0 +1,257 @@
+import { Inject } from '@nestjs/common';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports -- NestJS DI requires value imports
+import { CommandBus } from '@nestjs/cqrs';
+import { OnEvent } from '@nestjs/event-emitter';
+import {
+  WebSocketGateway,
+  WebSocketServer,
+  SubscribeMessage,
+  MessageBody,
+  ConnectedSocket,
+  type OnGatewayConnection,
+  type OnGatewayDisconnect,
+  type OnGatewayInit,
+} from '@nestjs/websockets';
+import type { Server, Socket } from 'socket.io';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports -- NestJS DI requires value imports
+import { TokenService, type JwtPayload } from '@modules/auth';
+// eslint-disable-next-line @typescript-eslint/consistent-type-imports -- NestJS DI requires value imports
+import { LoggerService } from '@modules/shared';
+import { MarkConversationReadCommand } from '../../application/commands/mark-read/mark-read.command';
+import { SendMessageCommand } from '../../application/commands/send-message/send-message.command';
+import type { MessageSentEvent } from '../../domain/events/message-sent.event';
+import {
+  CONVERSATION_REPOSITORY,
+  type IConversationRepository,
+} from '../../domain/repositories/conversation.repository';
+
+@WebSocketGateway({
+  namespace: '/messaging',
+  cors: {
+    origin: (process.env['CORS_ORIGINS'] ?? 'http://localhost:3000')
+      .split(',')
+      .map((o) => o.trim()),
+    credentials: true,
+  },
+})
+export class MessagingGateway
+  implements OnGatewayInit, OnGatewayConnection, OnGatewayDisconnect
+{
+  @WebSocketServer()
+  server!: Server;
+
+  private readonly userSockets = new Map<string, Set<string>>();
+
+  constructor(
+    private readonly tokenService: TokenService,
+    private readonly logger: LoggerService,
+    private readonly commandBus: CommandBus,
+    @Inject(CONVERSATION_REPOSITORY)
+    private readonly conversationRepo: IConversationRepository,
+  ) {}
+
+  afterInit(): void {
+    this.logger.log('MessagingGateway initialized', 'MessagingGateway');
+  }
+
+  async handleConnection(client: Socket): Promise<void> {
+    try {
+      const payload = this.extractAndVerifyToken(client);
+      if (!payload) {
+        client.disconnect(true);
+        return;
+      }
+
+      client.data['userId'] = payload.sub;
+
+      // Join user's personal room for direct messaging events
+      await client.join(`user:${payload.sub}`);
+
+      // Join rooms for all active conversations
+      const conversations = await this.conversationRepo.findByUserId(payload.sub, 100);
+      for (const conv of conversations) {
+        await client.join(`conversation:${conv.id}`);
+      }
+
+      if (!this.userSockets.has(payload.sub)) {
+        this.userSockets.set(payload.sub, new Set());
+      }
+      this.userSockets.get(payload.sub)!.add(client.id);
+
+      this.logger.debug(
+        `WS messaging connected: user=${payload.sub} socket=${client.id} conversations=${conversations.length}`,
+        'MessagingGateway',
+      );
+    } catch (error) {
+      this.logger.error(
+        `WS messaging connection error: ${error instanceof Error ? error.message : error}`,
+        error instanceof Error ? error.stack : undefined,
+        'MessagingGateway',
+      );
+      client.disconnect(true);
+    }
+  }
+
+  handleDisconnect(client: Socket): void {
+    const userId = client.data['userId'] as string | undefined;
+    if (userId) {
+      const sockets = this.userSockets.get(userId);
+      if (sockets) {
+        sockets.delete(client.id);
+        if (sockets.size === 0) {
+          this.userSockets.delete(userId);
+        }
+      }
+    }
+    this.logger.debug(
+      `WS messaging disconnected: user=${userId ?? 'unknown'} socket=${client.id}`,
+      'MessagingGateway',
+    );
+  }
+
+  /* ────────────────────────────────────────────
+   * Client → Server message handlers
+   * ──────────────────────────────────────────── */
+
+  @SubscribeMessage('message:send')
+  async handleSendMessage(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() data: { conversationId: string; content: string; type?: string },
+  ): Promise<void> {
+    const userId = client.data['userId'] as string;
+    if (!userId) return;
+
+    try {
+      const message = await this.commandBus.execute(
+        new SendMessageCommand(
+          data.conversationId,
+          userId,
+          data.content,
+          (data.type as 'TEXT' | 'IMAGE' | 'FILE') ?? 'TEXT',
+        ),
+      );
+      client.emit('message:sent', { messageId: message.id, conversationId: data.conversationId });
+    } catch (error) {
+      client.emit('message:error', {
+        conversationId: data.conversationId,
+        error: error instanceof Error ? error.message : 'Không thể gửi tin nhắn',
+      });
+    }
+  }
+
+  @SubscribeMessage('message:typing')
+  async handleTyping(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() data: { conversationId: string },
+  ): Promise<void> {
+    const userId = client.data['userId'] as string;
+    if (!userId) return;
+
+    client.to(`conversation:${data.conversationId}`).emit('message:typing', {
+      conversationId: data.conversationId,
+      userId,
+    });
+  }
+
+  @SubscribeMessage('message:stop-typing')
+  async handleStopTyping(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() data: { conversationId: string },
+  ): Promise<void> {
+    const userId = client.data['userId'] as string;
+    if (!userId) return;
+
+    client.to(`conversation:${data.conversationId}`).emit('message:stop-typing', {
+      conversationId: data.conversationId,
+      userId,
+    });
+  }
+
+  @SubscribeMessage('conversation:read')
+  async handleMarkRead(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() data: { conversationId: string },
+  ): Promise<void> {
+    const userId = client.data['userId'] as string;
+    if (!userId) return;
+
+    try {
+      await this.commandBus.execute(
+        new MarkConversationReadCommand(data.conversationId, userId),
+      );
+      client.emit('conversation:read-ack', { conversationId: data.conversationId });
+    } catch {
+      // Non-critical — silently fail
+    }
+  }
+
+  @SubscribeMessage('conversation:join')
+  async handleJoinConversation(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() data: { conversationId: string },
+  ): Promise<void> {
+    const userId = client.data['userId'] as string;
+    if (!userId) return;
+
+    // Verify the user is a participant before joining the room
+    const conversation = await this.conversationRepo.findById(data.conversationId);
+    if (conversation && conversation.participants.some((p) => p.userId === userId)) {
+      await client.join(`conversation:${data.conversationId}`);
+    }
+  }
+
+  /* ────────────────────────────────────────────
+   * Domain event handlers
+   * ──────────────────────────────────────────── */
+
+  @OnEvent('message.sent', { async: true })
+  async handleMessageSent(event: MessageSentEvent): Promise<void> {
+    try {
+      this.server.to(`conversation:${event.conversationId}`).emit('message:new', {
+        id: event.aggregateId,
+        conversationId: event.conversationId,
+        senderId: event.senderId,
+        type: event.type,
+        content: event.content,
+        createdAt: event.occurredAt.toISOString(),
+      });
+    } catch (error) {
+      this.logger.error(
+        `Failed to emit WS message for conversation ${event.conversationId}: ${
+          error instanceof Error ? error.message : error
+        }`,
+        error instanceof Error ? error.stack : undefined,
+        'MessagingGateway',
+      );
+    }
+  }
+
+  /* ────────────────────────────────────────────
+   * Private helpers
+   * ──────────────────────────────────────────── */
+
+  private extractAndVerifyToken(client: Socket): JwtPayload | null {
+    const raw: unknown =
+      client.handshake.auth?.['token'] ??
+      client.handshake.headers?.['authorization'] ??
+      client.handshake.query?.['token'];
+
+    if (!raw || typeof raw !== 'string') {
+      this.logger.warn(
+        `WS messaging auth failed: no token provided (socket=${client.id})`,
+        'MessagingGateway',
+      );
+      return null;
+    }
+
+    const token = raw.startsWith('Bearer ') ? raw.slice(7) : raw;
+    const payload = this.tokenService.verifyAccessToken(token);
+    if (!payload) {
+      this.logger.warn(
+        `WS messaging auth failed: invalid token (socket=${client.id})`,
+        'MessagingGateway',
+      );
+    }
+    return payload;
+  }
+}
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -880,3 +880,212 @@ model Review {
  @@index([userId])
  @@index([targetType, targetId, createdAt(sort: Desc)])
 }
+
+// =============================================================================
+// INDUSTRIAL PARKS (KCN)
+// =============================================================================
+
+enum IndustrialParkStatus {
+  PLANNING
+  UNDER_CONSTRUCTION
+  OPERATIONAL
+  FULL
+}
+
+enum IndustrialPropertyType {
+  INDUSTRIAL_LAND
+  READY_BUILT_FACTORY
+  READY_BUILT_WAREHOUSE
+  LOGISTICS_CENTER
+  OFFICE_IN_PARK
+  DATA_CENTER
+}
+
+enum IndustrialLeaseType {
+  LAND_LEASE
+  FACTORY_LEASE
+  WAREHOUSE_LEASE
+  SUBLEASE
+}
+
+enum IndustrialListingStatus {
+  DRAFT
+  ACTIVE
+  RESERVED
+  LEASED
+  EXPIRED
+}
+
+enum VietnamRegion {
+  NORTH
+  CENTRAL
+  SOUTH
+}
+
+model IndustrialPark {
+  id                String                               @id @default(cuid())
+  name              String
+  nameEn            String?
+  slug              String                               @unique
+  developer         String
+  operator          String?
+  status            IndustrialParkStatus                 @default(PLANNING)
+  location          Unsupported("geometry(Point, 4326)")
+  address           String
+  district          String
+  province          String
+  region            VietnamRegion
+  totalAreaHa       Float
+  leasableAreaHa    Float
+  occupancyRate     Float                                @default(0) // 0-100
+  remainingAreaHa   Float
+  tenantCount       Int                                  @default(0)
+  establishedYear   Int?
+  landRentUsdM2Year Float?
+  rbfRentUsdM2Month Float?
+  rbwRentUsdM2Month Float?
+  managementFeeUsd  Float?
+  infrastructure    Json? // { electricity, water, wastewater, telecom, roads, fire }
+  connectivity      Json? // { nearestPort, airport, highway, railway, seaport }
+  incentives        Json? // { taxHoliday, importDuty, landRentReduction, specialZone }
+  targetIndustries  String[]
+  existingTenants   Json? // [{ name, country, industry }]
+  certifications    Json? // ["ISO 14001", "Green park"]
+  media             Json?
+  documents         Json?
+  description       String?                              @db.Text
+  descriptionEn     String?                              @db.Text
+  isVerified        Boolean                              @default(false)
+  createdAt         DateTime                             @default(now())
+  updatedAt         DateTime                             @updatedAt
+
+  listings IndustrialListing[]
+
+  @@index([status])
+  @@index([province])
+  @@index([region])
+  @@index([developer])
+  @@index([location], type: Gist)
+  @@index([isVerified])
+  @@index([occupancyRate])
+  @@index([landRentUsdM2Year])
+  @@index([region, province, status])
+  @@index([createdAt])
+}
+
+model IndustrialListing {
+  id                String                               @id @default(cuid())
+  parkId            String
+  park              IndustrialPark                       @relation(fields: [parkId], references: [id], onDelete: Cascade)
+  agentId           String?
+  sellerId          String
+  propertyType      IndustrialPropertyType
+  leaseType         IndustrialLeaseType
+  status            IndustrialListingStatus              @default(DRAFT)
+  title             String
+  description       String?                              @db.Text
+  areaM2            Float
+  ceilingHeightM    Float?
+  floorLoadTonM2    Float?
+  columnSpacingM    Float?
+  dockCount         Int?
+  craneCapacityTon  Float?
+  hasMezzanine      Boolean                              @default(false)
+  hasOfficeArea     Boolean                              @default(false)
+  officeAreaM2      Float?
+  priceUsdM2        Float?
+  pricingUnit       String? // "usd/m2/month", "usd/m2/year"
+  totalLeasePrice   Float?
+  managementFee     Float?
+  depositMonths     Int?
+  minLeaseYears     Int?
+  maxLeaseYears     Int?
+  leaseExpiry       DateTime?
+  availableFrom     DateTime?
+  powerCapacityKva  Float?
+  waterSupplyM3Day  Float?
+  media             Json?
+  viewCount         Int                                  @default(0)
+  inquiryCount      Int                                  @default(0)
+  publishedAt       DateTime?
+  createdAt         DateTime                             @default(now())
+  updatedAt         DateTime                             @updatedAt
+
+  @@index([parkId])
+  @@index([propertyType])
+  @@index([leaseType])
+  @@index([status])
+  @@index([areaM2])
+  @@index([priceUsdM2])
+  @@index([sellerId])
+  @@index([agentId])
+  @@index([publishedAt])
+  @@index([parkId, status])
+  @@index([propertyType, leaseType, status])
+  @@index([status, publishedAt(sort: Desc)])
+}
+
+// =============================================================================
+// MESSAGING (buyer ↔ agent / seller in-app chat)
+// =============================================================================
+
+enum ConversationStatus {
+  ACTIVE
+  ARCHIVED
+  CLOSED
+}
+
+model Conversation {
+  id          String             @id @default(cuid())
+  listingId   String?
+  subject     String?
+  status      ConversationStatus @default(ACTIVE)
+  lastMessage String?            @db.Text
+  lastMessageAt DateTime?
+  createdAt   DateTime           @default(now())
+  updatedAt   DateTime           @updatedAt
+
+  participants ConversationParticipant[]
+  messages     Message[]
+
+  @@index([status])
+  @@index([lastMessageAt(sort: Desc)])
+  @@index([listingId])
+}
+
+model ConversationParticipant {
+  id             String       @id @default(cuid())
+  conversationId String
+  conversation   Conversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+  userId         String
+  unreadCount    Int          @default(0)
+  lastReadAt     DateTime?
+  joinedAt       DateTime     @default(now())
+
+  @@unique([conversationId, userId])
+  @@index([userId])
+  @@index([conversationId])
+}
+
+enum MessageType {
+  TEXT
+  IMAGE
+  FILE
+  SYSTEM
+}
+
+model Message {
+  id             String       @id @default(cuid())
+  conversationId String
+  conversation   Conversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+  senderId       String
+  type           MessageType  @default(TEXT)
+  content        String       @db.Text
+  metadata       Json?
+  editedAt       DateTime?
+  deletedAt      DateTime?
+  createdAt      DateTime     @default(now())
+
+  @@index([conversationId, createdAt])
+  @@index([senderId])
+}
				`@@ -0,0 +1 @@`
				`export type ConversationStatus = 'ACTIVE' \| 'ARCHIVED' \| 'CLOSED';`