diff --git a/Signal/Signal-Info.plist b/Signal/Signal-Info.plist
index 0e7535531..d5218f796 100644
--- a/Signal/Signal-Info.plist
+++ b/Signal/Signal-Info.plist
@@ -9,7 +9,7 @@
 		<key>OSXVersion</key>
 		<string>10.14.3</string>
 		<key>WebRTCCommit</key>
-		<string>55de5593cc261fa9368c5ccde98884ed1e278ba0 M72</string>
+		<string>1445d719bf05280270e9f77576f80f973fd847f8 M73</string>
 	</dict>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>en</string>
diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
index c0b18ad11..9aa7c893d 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
@@ -212,7 +212,7 @@ typedef enum : NSUInteger {
 @property (nonatomic, nullable) NSString *lastSearchedText;
 @property (nonatomic) BOOL isShowingSearchUI;
 @property (nonatomic, nullable) MenuActionsViewController *menuActionsViewController;
-@property (nonatomic) CGFloat contentInsetPadding;
+@property (nonatomic) CGFloat extraContentInsetPadding;
 
 @end
 
@@ -749,7 +749,7 @@ typedef enum : NSUInteger {
     if (!self.viewHasEverAppeared) {
         [self scrollToDefaultPosition];
     } else if (self.menuActionsViewController != nil) {
-        [self scrollToFocusInteraction:NO];
+        [self scrollToMenuActionInteraction:NO];
     }
 
     [self updateLastVisibleSortId];
@@ -763,7 +763,7 @@ typedef enum : NSUInteger {
 
 - (NSArray<id<ConversationViewItem>> *)viewItems
 {
-    return self.conversationViewModel.viewItems;
+    return self.conversationViewModel.viewState.viewItems;
 }
 
 - (ThreadDynamicInteractions *)dynamicInteractions
@@ -773,14 +773,11 @@ typedef enum : NSUInteger {
 
 - (NSIndexPath *_Nullable)indexPathOfUnreadMessagesIndicator
 {
-    NSInteger row = 0;
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        if (viewItem.unreadIndicator) {
-            return [NSIndexPath indexPathForRow:row inSection:0];
-        }
-        row++;
+    NSNumber *_Nullable unreadIndicatorIndex = self.conversationViewModel.viewState.unreadIndicatorIndex;
+    if (unreadIndicatorIndex == nil) {
+        return nil;
     }
-    return nil;
+    return [NSIndexPath indexPathForRow:unreadIndicatorIndex.integerValue inSection:0];
 }
 
 - (NSIndexPath *_Nullable)indexPathOfMessageOnOpen
@@ -1981,11 +1978,11 @@ typedef enum : NSUInteger {
     // which we might want to scroll to the bottom of the screen to
     // pin above the menu actions popup.
     CGSize mainScreenSize = UIScreen.mainScreen.bounds.size;
-    self.contentInsetPadding = MAX(mainScreenSize.width, mainScreenSize.height);
+    self.extraContentInsetPadding = MAX(mainScreenSize.width, mainScreenSize.height);
 
     UIEdgeInsets contentInset = self.collectionView.contentInset;
-    contentInset.top += self.contentInsetPadding;
-    contentInset.bottom += self.contentInsetPadding;
+    contentInset.top += self.extraContentInsetPadding;
+    contentInset.bottom += self.extraContentInsetPadding;
     self.collectionView.contentInset = contentInset;
 
     self.menuActionsViewController = menuActionsViewController;
@@ -1996,14 +1993,14 @@ typedef enum : NSUInteger {
     OWSLogVerbose(@"");
 
     // Changes made in this "is presenting" callback are animated by the caller.
-    [self scrollToFocusInteraction:NO];
+    [self scrollToMenuActionInteraction:NO];
 }
 
 - (void)menuActionsDidPresent:(MenuActionsViewController *)menuActionsViewController
 {
     OWSLogVerbose(@"");
 
-    [self scrollToFocusInteraction:NO];
+    [self scrollToMenuActionInteraction:NO];
 }
 
 - (void)menuActionsIsDismissing:(MenuActionsViewController *)menuActionsViewController
@@ -2038,24 +2035,26 @@ typedef enum : NSUInteger {
     }
 
     UIEdgeInsets contentInset = self.collectionView.contentInset;
-    contentInset.top -= self.contentInsetPadding;
-    contentInset.bottom -= self.contentInsetPadding;
+    contentInset.top -= self.extraContentInsetPadding;
+    contentInset.bottom -= self.extraContentInsetPadding;
     self.collectionView.contentInset = contentInset;
 
     self.menuActionsViewController = nil;
-    self.contentInsetPadding = 0;
+    self.extraContentInsetPadding = 0;
 }
 
-- (void)scrollToFocusInteractionIfNecessary
+- (void)scrollToMenuActionInteractionIfNecessary
 {
     if (self.menuActionsViewController != nil) {
-        [self scrollToFocusInteraction:NO];
+        [self scrollToMenuActionInteraction:NO];
     }
 }
 
-- (void)scrollToFocusInteraction:(BOOL)animated
+- (void)scrollToMenuActionInteraction:(BOOL)animated
 {
-    NSValue *_Nullable contentOffset = [self contentOffsetForFocusInteraction];
+    OWSAssertDebug(self.menuActionsViewController);
+
+    NSValue *_Nullable contentOffset = [self contentOffsetForMenuActionInteraction];
     if (contentOffset == nil) {
         OWSFailDebug(@"Missing contentOffset.");
         return;
@@ -2063,11 +2062,13 @@ typedef enum : NSUInteger {
     [self.collectionView setContentOffset:contentOffset.CGPointValue animated:animated];
 }
 
-- (nullable NSValue *)contentOffsetForFocusInteraction
+- (nullable NSValue *)contentOffsetForMenuActionInteraction
 {
-    NSString *_Nullable focusedInteractionId = self.menuActionsViewController.focusedInteraction.uniqueId;
-    if (focusedInteractionId == nil) {
-        // This is expected if there is no focus interaction.
+    OWSAssertDebug(self.menuActionsViewController);
+
+    NSString *_Nullable menuActionInteractionId = self.menuActionsViewController.focusedInteraction.uniqueId;
+    if (menuActionInteractionId == nil) {
+        OWSFailDebug(@"Missing menu action interaction.");
         return nil;
     }
     CGPoint modalTopWindow = [self.menuActionsViewController.focusUI convertPoint:CGPointZero toView:nil];
@@ -2075,18 +2076,13 @@ typedef enum : NSUInteger {
     CGPoint offset = modalTopLocal;
     CGFloat focusTop = offset.y - self.menuActionsViewController.vSpacing;
 
-    NSIndexPath *_Nullable indexPath = nil;
-    for (NSUInteger i = 0; i < self.viewItems.count; i++) {
-        id<ConversationViewItem> viewItem = self.viewItems[i];
-        if ([viewItem.interaction.uniqueId isEqualToString:focusedInteractionId]) {
-            indexPath = [NSIndexPath indexPathForRow:(NSInteger)i inSection:0];
-            break;
-        }
-    }
-    if (indexPath == nil) {
-        // This is expected if the focus interaction is being deleted.
+    NSNumber *_Nullable interactionIndex
+        = self.conversationViewModel.viewState.interactionIndexMap[menuActionInteractionId];
+    if (interactionIndex == nil) {
+        // This is expected if the menu action interaction is being deleted.
         return nil;
     }
+    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:interactionIndex.integerValue inSection:0];
     UICollectionViewLayoutAttributes *_Nullable layoutAttributes =
         [self.layout layoutAttributesForItemAtIndexPath:indexPath];
     if (layoutAttributes == nil) {
@@ -2109,16 +2105,12 @@ typedef enum : NSUInteger {
     if (!OWSWindowManager.sharedManager.isPresentingMenuActions) {
         return NO;
     }
-    NSString *_Nullable focusedInteractionId = self.menuActionsViewController.focusedInteraction.uniqueId;
-    if (focusedInteractionId == nil) {
+    NSString *_Nullable menuActionInteractionId = self.menuActionsViewController.focusedInteraction.uniqueId;
+    if (menuActionInteractionId == nil) {
         return NO;
     }
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        if ([viewItem.interaction.uniqueId isEqualToString:focusedInteractionId]) {
-            return NO;
-        }
-    }
-    return YES;
+    // Check whether there is still a view item for this interaction.
+    return (self.conversationViewModel.viewState.interactionIndexMap[menuActionInteractionId] == nil);
 }
 
 #pragma mark - ConversationViewCellDelegate
@@ -3857,8 +3849,8 @@ typedef enum : NSUInteger {
     newInsets.top = 0;
     newInsets.bottom = MAX(0, self.view.height - self.bottomLayoutGuide.length - keyboardEndFrameConverted.origin.y);
 
-    newInsets.top += self.contentInsetPadding;
-    newInsets.bottom += self.contentInsetPadding;
+    newInsets.top += self.extraContentInsetPadding;
+    newInsets.bottom += self.extraContentInsetPadding;
 
     BOOL wasScrolledToBottom = [self isScrolledToBottom];
 
@@ -4515,7 +4507,7 @@ typedef enum : NSUInteger {
     targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset
 {
     if (self.menuActionsViewController != nil) {
-        NSValue *_Nullable contentOffset = [self contentOffsetForFocusInteraction];
+        NSValue *_Nullable contentOffset = [self contentOffsetForMenuActionInteraction];
         if (contentOffset != nil) {
             return contentOffset.CGPointValue;
         }
@@ -4768,6 +4760,11 @@ typedef enum : NSUInteger {
     OWSAssertDebug(conversationUpdate);
     OWSAssertDebug(self.conversationViewModel);
 
+    if (!self.viewLoaded) {
+        OWSLogVerbose(@"Ignoring update; view has not yet loaded.");
+        return;
+    }
+
     [self updateBackButtonUnreadCount];
     [self updateNavigationBarSubtitleLabel];
     [self dismissMenuActionsIfNecessary];
@@ -5018,7 +5015,7 @@ typedef enum : NSUInteger {
             [strongSelf updateInputToolbarLayout];
 
             if (self.menuActionsViewController != nil) {
-                [self scrollToFocusInteraction:NO];
+                [self scrollToMenuActionInteraction:NO];
             } else if (lastVisibleIndexPath) {
                 [strongSelf.collectionView scrollToItemAtIndexPath:lastVisibleIndexPath
                                                   atScrollPosition:UICollectionViewScrollPositionBottom
diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewModel.h b/Signal/src/ViewControllers/ConversationView/ConversationViewModel.h
index b9fafcd2f..a4025f1f7 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewModel.h
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewModel.h
@@ -34,6 +34,19 @@ typedef NS_ENUM(NSUInteger, ConversationUpdateItemType) {
 
 #pragma mark -
 
+@interface ConversationViewState : NSObject
+
+@property (nonatomic, readonly) NSArray<id<ConversationViewItem>> *viewItems;
+@property (nonatomic, readonly) NSDictionary<NSString *, NSNumber *> *interactionIndexMap;
+// We have to track interactionIds separately.  We can't just use interactionIndexMap.allKeys,
+// as that won't preserve ordering.
+@property (nonatomic, readonly) NSArray<NSString *> *interactionIds;
+@property (nonatomic, readonly, nullable) NSNumber *unreadIndicatorIndex;
+
+@end
+
+#pragma mark -
+
 @interface ConversationUpdateItem : NSObject
 
 @property (nonatomic, readonly) ConversationUpdateItemType updateItemType;
@@ -82,7 +95,7 @@ typedef NS_ENUM(NSUInteger, ConversationUpdateItemType) {
 
 @interface ConversationViewModel : NSObject
 
-@property (nonatomic, readonly) NSArray<id<ConversationViewItem>> *viewItems;
+@property (nonatomic, readonly) ConversationViewState *viewState;
 @property (nonatomic, nullable) NSString *focusMessageIdOnOpen;
 @property (nonatomic, readonly, nullable) ThreadDynamicInteractions *dynamicInteractions;
 
diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewModel.m b/Signal/src/ViewControllers/ConversationView/ConversationViewModel.m
index 2bb7925a9..3c34ab266 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewModel.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewModel.m
@@ -44,6 +44,50 @@ NS_ASSUME_NONNULL_BEGIN
 
 #pragma mark -
 
+@implementation ConversationViewState
+
+- (instancetype)initWithViewItems:(NSArray<id<ConversationViewItem>> *)viewItems
+{
+    self = [super init];
+    if (!self) {
+        return self;
+    }
+
+    _viewItems = viewItems;
+    NSMutableDictionary<NSString *, NSNumber *> *interactionIndexMap = [NSMutableDictionary new];
+    NSMutableArray<NSString *> *interactionIds = [NSMutableArray new];
+    for (NSUInteger i = 0; i < self.viewItems.count; i++) {
+        id<ConversationViewItem> viewItem = self.viewItems[i];
+        interactionIndexMap[viewItem.interaction.uniqueId] = @(i);
+        [interactionIds addObject:viewItem.interaction.uniqueId];
+
+        if (viewItem.unreadIndicator != nil) {
+            _unreadIndicatorIndex = @(i);
+        }
+    }
+    _interactionIndexMap = [interactionIndexMap copy];
+    _interactionIds = [interactionIds copy];
+
+    return self;
+}
+
+- (nullable id<ConversationViewItem>)unreadIndicatorViewItem
+{
+    if (self.unreadIndicatorIndex == nil) {
+        return nil;
+    }
+    NSUInteger index = self.unreadIndicatorIndex.unsignedIntegerValue;
+    if (index >= self.viewItems.count) {
+        OWSFailDebug(@"Invalid index.");
+        return nil;
+    }
+    return self.viewItems[index];
+}
+
+@end
+
+#pragma mark -
+
 @implementation ConversationUpdateItem
 
 - (instancetype)initWithUpdateItemType:(ConversationUpdateItemType)updateItemType
@@ -150,7 +194,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
 // * Afterward, we must prod the view controller to update layout & view state.
 @property (nonatomic) ConversationMessageMapping *messageMapping;
 
-@property (nonatomic) NSArray<id<ConversationViewItem>> *viewItems;
+@property (nonatomic) ConversationViewState *viewState;
 @property (nonatomic) NSMutableDictionary<NSString *, id<ConversationViewItem>> *viewItemCache;
 
 @property (nonatomic, nullable) ThreadDynamicInteractions *dynamicInteractions;
@@ -187,6 +231,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
     _persistedViewItems = @[];
     _unsavedOutgoingMessages = @[];
     self.focusMessageIdOnOpen = focusMessageIdOnOpen;
+    _viewState = [[ConversationViewState alloc] initWithViewItems:@[]];
 
     [self configure];
 
@@ -492,22 +537,12 @@ static const int kYapDatabaseRangeMaxLength = 25000;
     }
 }
 
-- (nullable id<ConversationViewItem>)viewItemForUnreadMessagesIndicator
-{
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        if (viewItem.unreadIndicator) {
-            return viewItem;
-        }
-    }
-    return nil;
-}
-
 - (void)clearUnreadMessagesIndicator
 {
     OWSAssertIsOnMainThread();
 
     // TODO: Remove by making unread indicator a view model concern.
-    id<ConversationViewItem> _Nullable oldIndicatorItem = [self viewItemForUnreadMessagesIndicator];
+    id<ConversationViewItem> _Nullable oldIndicatorItem = [self.viewState unreadIndicatorViewItem];
     if (oldIndicatorItem) {
         // TODO ideally this would be happening within the *same* transaction that caused the unreadMessageIndicator
         // to be cleared.
@@ -613,10 +648,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
         }
     }
 
-    NSMutableArray<NSString *> *oldItemIdList = [NSMutableArray new];
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        [oldItemIdList addObject:viewItem.itemId];
-    }
+    NSArray<NSString *> *oldItemIdList = self.viewState.interactionIds;
 
     // We need to reload any modified interactions _before_ we call
     // reloadViewItems.
@@ -655,7 +687,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
         return;
     }
 
-    OWSLogVerbose(@"self.viewItems.count: %zd -> %zd", oldItemIdList.count, self.viewItems.count);
+    OWSLogVerbose(@"self.viewItems.count: %zd -> %zd", oldItemIdList.count, self.viewState.viewItems.count);
 
     [self updateViewWithOldItemIdList:oldItemIdList updatedItemSet:updatedItemSet];
 }
@@ -668,10 +700,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
 
     OWSLogVerbose(@"");
 
-    NSMutableArray<NSString *> *oldItemIdList = [NSMutableArray new];
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        [oldItemIdList addObject:viewItem.itemId];
-    }
+    NSArray<NSString *> *oldItemIdList = self.viewState.interactionIds;
 
     if (![self reloadViewItems]) {
         // These errors are rare.
@@ -682,7 +711,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
         return;
     }
 
-    OWSLogVerbose(@"self.viewItems.count: %zd -> %zd", oldItemIdList.count, self.viewItems.count);
+    OWSLogVerbose(@"self.viewItems.count: %zd -> %zd", oldItemIdList.count, self.viewState.viewItems.count);
 
     [self updateViewWithOldItemIdList:oldItemIdList updatedItemSet:[NSSet set]];
 }
@@ -698,10 +727,9 @@ static const int kYapDatabaseRangeMaxLength = 25000;
         return;
     }
 
-    NSMutableArray<NSString *> *newItemIdList = [NSMutableArray new];
+    NSArray<NSString *> *newItemIdList = self.viewState.interactionIds;
     NSMutableDictionary<NSString *, id<ConversationViewItem>> *newViewItemMap = [NSMutableDictionary new];
-    for (id<ConversationViewItem> viewItem in self.viewItems) {
-        [newItemIdList addObject:viewItem.itemId];
+    for (id<ConversationViewItem> viewItem in self.viewState.viewItems) {
         newViewItemMap[viewItem.itemId] = viewItem;
     }
 
@@ -1510,7 +1538,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
         viewItem.senderName = senderName;
     }
 
-    self.viewItems = viewItems;
+    self.viewState = [[ConversationViewState alloc] initWithViewItems:viewItems];
     self.viewItemCache = viewItemCache;
 
     return !hasError;
@@ -1661,7 +1689,7 @@ static const int kYapDatabaseRangeMaxLength = 25000;
 
     // Update the view items if necessary.
     // We don't have to do this if they haven't been configured yet.
-    if (didChange && self.viewItems != nil) {
+    if (didChange && self.viewState.viewItems != nil) {
         // When we receive an incoming message, we clear any typing indicators
         // from that sender.  Ideally, we'd like both changes (disappearance of
         // the typing indicators, appearance of the incoming message) to show up
diff --git a/Signal/src/ViewControllers/MenuActionsViewController.swift b/Signal/src/ViewControllers/MenuActionsViewController.swift
index c54dc0546..4e04f6c76 100644
--- a/Signal/src/ViewControllers/MenuActionsViewController.swift
+++ b/Signal/src/ViewControllers/MenuActionsViewController.swift
@@ -36,7 +36,7 @@ class MenuActionsViewController: UIViewController, MenuActionSheetDelegate {
     weak var delegate: MenuActionsViewControllerDelegate?
 
     @objc
-    public let focusedInteraction: TSInteraction?
+    public let focusedInteraction: TSInteraction
 
     private let focusedView: UIView
     private let actionSheetView: MenuActionSheetView
@@ -46,7 +46,7 @@ class MenuActionsViewController: UIViewController, MenuActionSheetDelegate {
     }
 
     @objc
-    required init(focusedInteraction: TSInteraction?, focusedView: UIView, actions: [MenuAction]) {
+    required init(focusedInteraction: TSInteraction, focusedView: UIView, actions: [MenuAction]) {
         self.focusedView = focusedView
         self.focusedInteraction = focusedInteraction
 
@@ -180,7 +180,7 @@ class MenuActionsViewController: UIViewController, MenuActionSheetDelegate {
     public let vSpacing: CGFloat = 10
 
     @objc
-    public func focusUI() -> UIView {
+    public var focusUI: UIView {
         return actionSheetView
     }