New feature flag with ability to migrate GV1 groups

ts/models/messages.ts

@@ -2079,33 +2079,42 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
     const isOutgoing = this.get('type') === 'outgoing';
     const numDelivered = this.get('delivered');
 
-    // Case 1: If mandatory profile sharing is enabled, and we haven't shared yet, then
+    if (!conversation) {
+      return false;
+    }
+
+    // If GroupV1 groups have been disabled, we can't reply.
+    if (conversation.isGroupV1AndDisabled()) {
+      return false;
+    }
+
+    // If mandatory profile sharing is enabled, and we haven't shared yet, then
     //   we can't reply.
-    if (conversation?.isMissingRequiredProfileSharing()) {
+    if (conversation.isMissingRequiredProfileSharing()) {
       return false;
     }
 
-    // Case 2: We cannot reply if we have accepted the message request
-    if (!conversation?.getAccepted()) {
+    // We cannot reply if we haven't accepted the message request
+    if (!conversation.getAccepted()) {
       return false;
     }
 
-    // Case 3: We cannot reply if this message is deleted for everyone
+    // We cannot reply if this message is deleted for everyone
     if (this.get('deletedForEveryone')) {
       return false;
     }
 
-    // Case 4: We can reply if this is outgoing and delievered to at least one recipient
+    // We can reply if this is outgoing and delievered to at least one recipient
     if (isOutgoing && numDelivered > 0) {
       return true;
     }
 
-    // Case 5: We can reply if there are no errors
+    // We can reply if there are no errors
     if (!errors || (errors && errors.length === 0)) {
       return true;
     }
 
-    // Case 6: default
+    // Fail safe.
     return false;
   }