Respond to CR.

// FREEBIE

SignalServiceKit/src/Messages/Interactions/TSInteraction.m

@@ -43,6 +43,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (instancetype)initWithTimestamp:(uint64_t)timestamp inThread:(TSThread *)thread
 {
+    OWSAssert(timestamp > 0);
+
     self = [super initWithUniqueId:nil];
 
     if (!self) {

SignalServiceKit/src/Messages/OWSDisappearingMessagesJob.m

@@ -266,14 +266,14 @@ NS_ASSUME_NONNULL_BEGIN
         TSIncomingMessage *incomingMessage = (TSIncomingMessage *)message;
         NSString *contactName = [contactsManager displayNameForPhoneIdentifier:incomingMessage.messageAuthorId];
 
-        // We want the info message to appear after the message.
-        [[[OWSDisappearingConfigurationUpdateInfoMessage alloc] initWithTimestamp:message.timestamp + 1
+        // We want the info message to appear _before_ the message.
+        [[[OWSDisappearingConfigurationUpdateInfoMessage alloc] initWithTimestamp:message.timestamp - 1
                                                                            thread:message.thread
                                                                     configuration:disappearingMessagesConfiguration
                                                               createdByRemoteName:contactName] save];
     } else {
-        // We want the info message to appear after the message.
-        [[[OWSDisappearingConfigurationUpdateInfoMessage alloc] initWithTimestamp:message.timestamp + 1
+        // We want the info message to appear _before_ the message.
+        [[[OWSDisappearingConfigurationUpdateInfoMessage alloc] initWithTimestamp:message.timestamp - 1
                                                                            thread:message.thread
                                                                     configuration:disappearingMessagesConfiguration]
             save];

SignalServiceKit/src/Messages/OWSMessageManager.m

@@ -193,7 +193,7 @@ NS_ASSUME_NONNULL_BEGIN
     } else {
         // Desktop currently sends delivery receipts for "unpersisted" messages
         // like group updates, so these errors are expected to a certain extent.
-        DDLogError(@"%@ Unexpected message with timestamp: %llu", self.tag, envelope.timestamp);
+        DDLogInfo(@"%@ Unexpected message with timestamp: %llu", self.tag, envelope.timestamp);
     }
 }
 

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -434,7 +434,13 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         //
         // That's key - we don't want to send any messages in response
         // to an incoming message until processing of that batch of messages
-        // is complete.
+        // is complete.  For example, we wouldn't want to auto-reply to a
+        // group info request before that group info request's batch was
+        // finished processing.  Otherwise, we might receive a delivery
+        // notice for a group update we hadn't yet saved to the db.
+        //
+        // So we're using YDB behavior to ensure this invariant, which is a bit
+        // unorthodox.
         [message updateWithMessageState:TSOutgoingMessageStateAttemptingOut];
 
         OWSSendMessageOperation *sendMessageOperation =
@@ -1328,14 +1334,12 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
         // TODO: Why is this necessary?
         [message save];
     } else if (message.groupMetaMessage == TSGroupMessageQuit) {
-        // We want the info message to appear after the message.
-        [[[TSInfoMessage alloc] initWithTimestamp:message.timestamp + 1
+        [[[TSInfoMessage alloc] initWithTimestamp:message.timestamp
                                          inThread:thread
                                       messageType:TSInfoMessageTypeGroupQuit
                                     customMessage:message.customMessage] save];
     } else {
-        // We want the info message to appear after the message.
-        [[[TSInfoMessage alloc] initWithTimestamp:message.timestamp + 1
+        [[[TSInfoMessage alloc] initWithTimestamp:message.timestamp
                                          inThread:thread
                                       messageType:TSInfoMessageTypeGroupUpdate
                                     customMessage:message.customMessage] save];