feat: implement per-user soft delete for conversations with automatic restoration on new messages

prisma/schema.prisma

@@ -507,6 +507,10 @@ model Conversation {
   userClearedAt    DateTime?
   agentClearedAt   DateTime?
 
+  // Soft delete (per-user) — conversation hidden for that user until a new message arrives
+  userDeletedAt    DateTime?
+  agentDeletedAt   DateTime?
+
   // Timestamps
   createdAt        DateTime  @default(now())
   updatedAt        DateTime  @updatedAt

src/messages/messages.service.ts

@@ -140,6 +140,21 @@ export class MessagesService {
         },
         include: conversationInclude,
       });
+    } else {
+      // Clear soft-delete flag for the caller so the conversation reappears
+      const needsClear = callerRole === UserRole.AGENT
+        ? conversation.agentDeletedAt !== null
+        : conversation.userDeletedAt !== null;
+
+      if (needsClear) {
+        conversation = await this.prisma.conversation.update({
+          where: { id: conversation.id },
+          data: callerRole === UserRole.AGENT
+            ? { agentDeletedAt: null }
+            : { userDeletedAt: null },
+          include: conversationInclude,
+        });
+      }
     }
 
     // Transform to include otherParty based on caller role
@@ -275,6 +290,9 @@ export class MessagesService {
         ...(isUser
           ? { agentUnreadCount: { increment: 1 } }
           : { userUnreadCount: { increment: 1 } }),
+        // Clear soft-delete flags so conversation reappears for both parties
+        userDeletedAt: null,
+        agentDeletedAt: null,
       },
     });
 
@@ -315,7 +333,10 @@ export class MessagesService {
       }
 
       conversations = await this.prisma.conversation.findMany({
-        where: { agentProfileId: agentProfile.id },
+        where: {
+          agentProfileId: agentProfile.id,
+          agentDeletedAt: null, // Exclude soft-deleted conversations
+        },
         include: {
           user: {
             select: {
@@ -362,7 +383,10 @@ export class MessagesService {
     } else {
       // Regular user
       conversations = await this.prisma.conversation.findMany({
-        where: { userId },
+        where: {
+          userId,
+          userDeletedAt: null, // Exclude soft-deleted conversations
+        },
         include: {
           agentProfile: {
             select: {
@@ -781,13 +805,17 @@ export class MessagesService {
       throw new ForbiddenException('You are not part of this conversation');
     }
 
-    // Delete all messages first, then the conversation
-    await this.prisma.message.deleteMany({
-      where: { conversationId },
-    });
+    // Soft delete: mark conversation as deleted for this user only
+    // The other party still sees the conversation and all messages.
+    // If a new message arrives later, the deletedAt flag is cleared so
+    // the conversation reappears for the user who deleted it.
+    const now = new Date();
 
-    await this.prisma.conversation.delete({
+    await this.prisma.conversation.update({
       where: { id: conversationId },
+      data: isUser
+        ? { userDeletedAt: now, userClearedAt: now, userUnreadCount: 0 }
+        : { agentDeletedAt: now, agentClearedAt: now, agentUnreadCount: 0 },
     });
 
     return null;