feat: Implement direct notification for new messages and read receipts to conversation participants.

src/messages/messages.service.ts

@@ -555,6 +555,28 @@ export class MessagesService {
     }
   }
 
+  /**
+   * Get participant user IDs for a conversation (lightweight query)
+   */
+  async getConversationParticipants(conversationId: string): Promise<{ userId: string; agentUserId: string } | null> {
+    const conversation = await this.prisma.conversation.findUnique({
+      where: { id: conversationId },
+      select: {
+        userId: true,
+        agentProfile: {
+          select: { userId: true },
+        },
+      },
+    });
+
+    if (!conversation) return null;
+
+    return {
+      userId: conversation.userId,
+      agentUserId: conversation.agentProfile.userId,
+    };
+  }
+
   /**
    * Get total unread count for a user across all conversations
    */