fix: Prevent getOrCreateChat race conditions with a transaction and extract common chat include fields.

src/support-chat/support-chat.service.ts

@@ -10,50 +10,40 @@ import { SupportChatStatus } from '@prisma/client';
 export class SupportChatService {
   constructor(private readonly prisma: PrismaService) {}
 
-  /**
-   * Get or create an OPEN support chat for a user
-   */
-  async getOrCreateChat(userId: string) {
-    // Find existing OPEN chat
-    let chat = await this.prisma.supportChat.findFirst({
-      where: { userId, status: SupportChatStatus.OPEN },
-      include: {
-        user: {
-          select: {
-            id: true,
-            email: true,
-            userProfile: {
-              select: { firstName: true, lastName: true, avatar: true },
-            },
-            agentProfile: {
-              select: { firstName: true, lastName: true, avatar: true },
-            },
-          },
+  private readonly chatInclude = {
+    user: {
+      select: {
+        id: true,
+        email: true,
+        userProfile: {
+          select: { firstName: true, lastName: true, avatar: true },
+        },
+        agentProfile: {
+          select: { firstName: true, lastName: true, avatar: true },
         },
       },
-    });
+    },
+  };
 
-    if (!chat) {
-      chat = await this.prisma.supportChat.create({
-        data: { userId },
-        include: {
-          user: {
-            select: {
-              id: true,
-              email: true,
-              userProfile: {
-                select: { firstName: true, lastName: true, avatar: true },
-              },
-              agentProfile: {
-                select: { firstName: true, lastName: true, avatar: true },
-              },
-            },
-          },
-        },
+  /**
+   * Get or create an OPEN support chat for a user.
+   * Uses a transaction to prevent race conditions creating duplicates.
+   */
+  async getOrCreateChat(userId: string) {
+    return this.prisma.$transaction(async (tx) => {
+      // Find existing OPEN chat
+      const existing = await tx.supportChat.findFirst({
+        where: { userId, status: SupportChatStatus.OPEN },
+        include: this.chatInclude,
       });
-    }
 
-    return chat;
+      if (existing) return existing;
+
+      return tx.supportChat.create({
+        data: { userId },
+        include: this.chatInclude,
+      });
+    });
   }
 
   /**