feat(guild-messaging): support message metadata for reply mentions and attachments

Fabric.Backend.Guild/src/messaging/messaging.controller.ts

@@ -1,9 +1,15 @@
 import { Body, Controller, Delete, Get, Param, Patch, Post, Query } from '@nestjs/common';
+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;
 };
 
 @Controller('channels/:id/messages')
@@ -12,14 +18,19 @@ export class MessagingController {
   private messagesByChannel = new Map<string, Message[]>();
 
   @Post()
-  create(@Param('id') channelId: string, @Body() body: { content?: string; messageId?: string }) {
+  create(@Param('id') channelId: string, @Body() body: CreateMessageDto) {
     const next = (this.seqByChannel.get(channelId) ?? 0) + 1;
     this.seqByChannel.set(channelId, next);
 
     const message: Message = {
-      messageId: body.messageId ?? `m-${channelId}-${next}`,
+      messageId: body.clientMessageId ?? `m-${channelId}-${next}`,
       seq: next,
-      content: body.content ?? '',
+      content: body.content,
+      authorUserId: body.authorUserId ?? 'anonymous',
+      replyToMessageId: body.replyToMessageId ?? null,
+      mentions: body.mentions ?? [],
+      attachments: body.attachments ?? [],
+      createdAt: new Date().toISOString(),
     };
 
     const arr = this.messagesByChannel.get(channelId) ?? [];