Don’t hide threads if they are a group thread, or if they have _ever_ had a message.

// FREEBIE

SignalServiceKit/src/Contacts/TSThread.h

@@ -16,6 +16,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface TSThread : TSYapDatabaseObject
 
+// YES IFF this thread has ever had a message.
+@property (nonatomic) BOOL hasEverHadMessage;
+
 /**
  *  Whether the object is a group thread or not.
  *

SignalServiceKit/src/Contacts/TSThread.m

@@ -321,6 +321,8 @@ NS_ASSUME_NONNULL_BEGIN
         return;
     }
 
+    self.hasEverHadMessage = YES;
+
     NSDate *lastMessageDate = [lastMessage dateForSorting];
     if (!_lastMessageDate || [lastMessageDate timeIntervalSinceDate:self.lastMessageDate] > 0) {
         _lastMessageDate = lastMessageDate;

SignalServiceKit/src/Storage/TSDatabaseView.m

@@ -224,11 +224,17 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
 
         TSThread *thread = (TSThread *)object;
 
-        YapDatabaseViewTransaction *viewTransaction = [transaction ext:TSMessageDatabaseViewExtensionName];
+        if (thread.isGroupThread) {
-        OWSAssert(viewTransaction);
+            // Do nothing; we never hide group threads.
-        NSUInteger threadMessageCount = [viewTransaction numberOfItemsInGroup:thread.uniqueId];
+        } else if (thread.hasEverHadMessage) {
-        if (threadMessageCount < 1) {
+            // Do nothing; we never hide threads that have ever had a message.
-            return nil;
+        } else {
+            YapDatabaseViewTransaction *viewTransaction = [transaction ext:TSMessageDatabaseViewExtensionName];
+            OWSAssert(viewTransaction);
+            NSUInteger threadMessageCount = [viewTransaction numberOfItemsInGroup:thread.uniqueId];
+            if (threadMessageCount < 1) {
+                return nil;
+            }
         }
 
         if (thread.archivalDate) {
@@ -248,7 +254,7 @@ NSString *const TSSecondaryDevicesDatabaseViewExtensionName = @"TSSecondaryDevic
         [[YapWhitelistBlacklist alloc] initWithWhitelist:[NSSet setWithObject:[TSThread collection]]];
 
     YapDatabaseView *databaseView =
-        [[YapDatabaseView alloc] initWithGrouping:viewGrouping sorting:viewSorting versionTag:@"2" options:options];
+        [[YapDatabaseView alloc] initWithGrouping:viewGrouping sorting:viewSorting versionTag:@"3" options:options];
 
     [[TSStorageManager sharedManager].database registerExtension:databaseView
                                                         withName:TSThreadDatabaseViewExtensionName];