diff --git a/lib/selectors/chat-selectors.js b/lib/selectors/chat-selectors.js
index e0f0cc5c5..089259f05 100644
--- a/lib/selectors/chat-selectors.js
+++ b/lib/selectors/chat-selectors.js
@@ -1,609 +1,613 @@
 // @flow
 
 import invariant from 'invariant';
 import _filter from 'lodash/fp/filter';
 import _flow from 'lodash/fp/flow';
 import _map from 'lodash/fp/map';
 import _orderBy from 'lodash/fp/orderBy';
 import * as React from 'react';
 import { useSelector } from 'react-redux';
 import { createSelector } from 'reselect';
 import { createObjectSelector } from 'reselect-map';
 
 import {
   messageKey,
   robotextForMessageInfo,
   createMessageInfo,
   getMostRecentNonLocalMessageID,
   sortMessageInfoList,
 } from '../shared/message-utils';
 import {
   threadIsPending,
   threadIsTopLevel,
   threadInChatList,
 } from '../shared/thread-utils';
 import {
   type MessageInfo,
   type MessageStore,
   type ComposableMessageInfo,
   type RobotextMessageInfo,
   type LocalMessageInfo,
   messageTypes,
   isComposableMessageType,
 } from '../types/message-types';
 import type { BaseAppState } from '../types/redux-types';
 import {
   type ThreadInfo,
   type RawThreadInfo,
   type SidebarInfo,
   maxReadSidebars,
   maxUnreadSidebars,
   threadTypes,
 } from '../types/thread-types';
 import type {
   UserInfo,
   AccountUserInfo,
   RelativeUserInfo,
 } from '../types/user-types';
 import { threeDays } from '../utils/date-utils';
 import memoize2 from '../utils/memoize';
 import {
   threadInfoSelector,
   sidebarInfoSelector,
   threadInfoFromSourceMessageIDSelector,
 } from './thread-selectors';
 
 export type SidebarItem =
   | {
       ...SidebarInfo,
       +type: 'sidebar',
     }
   | {
       +type: 'seeMore',
       +unread: boolean,
     }
   | { +type: 'spacer' };
 
 export type ChatThreadItem = {
   +type: 'chatThreadItem',
   +threadInfo: ThreadInfo,
   +mostRecentMessageInfo: ?MessageInfo,
   +mostRecentNonLocalMessage: ?string,
   +lastUpdatedTime: number,
   +lastUpdatedTimeIncludingSidebars: number,
   +sidebars: $ReadOnlyArray<SidebarItem>,
   +pendingPersonalThreadUserInfo?: UserInfo,
 };
 
 const messageInfoSelector: (
   state: BaseAppState<*>,
 ) => { +[id: string]: ?MessageInfo } = createObjectSelector(
   (state: BaseAppState<*>) => state.messageStore.messages,
   (state: BaseAppState<*>) => state.currentUserInfo && state.currentUserInfo.id,
   (state: BaseAppState<*>) => state.userStore.userInfos,
   threadInfoSelector,
   createMessageInfo,
 );
 
 function isEmptyMediaMessage(messageInfo: MessageInfo): boolean {
   return (
     (messageInfo.type === messageTypes.MULTIMEDIA ||
       messageInfo.type === messageTypes.IMAGES) &&
     messageInfo.media.length === 0
   );
 }
 
 function getMostRecentMessageInfo(
   threadInfo: ThreadInfo,
   messageStore: MessageStore,
   messages: { +[id: string]: ?MessageInfo },
 ): ?MessageInfo {
   const thread = messageStore.threads[threadInfo.id];
   if (!thread) {
     return null;
   }
   for (const messageID of thread.messageIDs) {
     const messageInfo = messages[messageID];
     if (!messageInfo || isEmptyMediaMessage(messageInfo)) {
       continue;
     }
     return messageInfo;
   }
   return null;
 }
 
 function getLastUpdatedTime(
   threadInfo: ThreadInfo,
   mostRecentMessageInfo: ?MessageInfo,
 ): number {
   return mostRecentMessageInfo
     ? mostRecentMessageInfo.time
     : threadInfo.creationTime;
 }
 
 function createChatThreadItem(
   threadInfo: ThreadInfo,
   messageStore: MessageStore,
   messages: { +[id: string]: ?MessageInfo },
   sidebarInfos: ?$ReadOnlyArray<SidebarInfo>,
 ): ChatThreadItem {
   const mostRecentMessageInfo = getMostRecentMessageInfo(
     threadInfo,
     messageStore,
     messages,
   );
   const mostRecentNonLocalMessage = getMostRecentNonLocalMessageID(
     threadInfo.id,
     messageStore,
   );
   const lastUpdatedTime = getLastUpdatedTime(threadInfo, mostRecentMessageInfo);
 
   const sidebars = sidebarInfos ?? [];
   const allSidebarItems = sidebars.map(sidebarInfo => ({
     type: 'sidebar',
     ...sidebarInfo,
   }));
   const lastUpdatedTimeIncludingSidebars =
     allSidebarItems.length > 0
       ? Math.max(lastUpdatedTime, allSidebarItems[0].lastUpdatedTime)
       : lastUpdatedTime;
 
   const numUnreadSidebars = allSidebarItems.filter(
     sidebar => sidebar.threadInfo.currentUser.unread,
   ).length;
   let numReadSidebarsToShow = maxReadSidebars - numUnreadSidebars;
   const threeDaysAgo = Date.now() - threeDays;
 
   const sidebarItems = [];
   for (const sidebar of allSidebarItems) {
     if (sidebarItems.length >= maxUnreadSidebars) {
       break;
     } else if (sidebar.threadInfo.currentUser.unread) {
       sidebarItems.push(sidebar);
     } else if (
       sidebar.lastUpdatedTime > threeDaysAgo &&
       numReadSidebarsToShow > 0
     ) {
       sidebarItems.push(sidebar);
       numReadSidebarsToShow--;
     }
   }
 
   const numReadButRecentSidebars = allSidebarItems.filter(
     sidebar =>
       !sidebar.threadInfo.currentUser.unread &&
       sidebar.lastUpdatedTime > threeDaysAgo,
   ).length;
   if (
     sidebarItems.length < numUnreadSidebars + numReadButRecentSidebars ||
     (sidebarItems.length < allSidebarItems.length && sidebarItems.length > 0)
   ) {
     sidebarItems.push({
       type: 'seeMore',
       unread: numUnreadSidebars > maxUnreadSidebars,
     });
   }
   if (sidebarItems.length !== 0) {
     sidebarItems.push({
       type: 'spacer',
     });
   }
 
   return {
     type: 'chatThreadItem',
     threadInfo,
     mostRecentMessageInfo,
     mostRecentNonLocalMessage,
     lastUpdatedTime,
     lastUpdatedTimeIncludingSidebars,
     sidebars: sidebarItems,
   };
 }
 
 const chatListData: (
   state: BaseAppState<*>,
 ) => $ReadOnlyArray<ChatThreadItem> = createSelector(
   threadInfoSelector,
   (state: BaseAppState<*>) => state.messageStore,
   messageInfoSelector,
   sidebarInfoSelector,
   (
     threadInfos: { +[id: string]: ThreadInfo },
     messageStore: MessageStore,
     messageInfos: { +[id: string]: ?MessageInfo },
     sidebarInfos: { +[id: string]: $ReadOnlyArray<SidebarInfo> },
   ): $ReadOnlyArray<ChatThreadItem> =>
     getChatThreadItems(
       threadInfos,
       messageStore,
       messageInfos,
       sidebarInfos,
       threadIsTopLevel,
     ),
 );
 
 function useFlattenedChatListData(): $ReadOnlyArray<ChatThreadItem> {
   return useFilteredChatListData(threadInChatList);
 }
 
 function useFilteredChatListData(
   filterFunction: (threadInfo: ?(ThreadInfo | RawThreadInfo)) => boolean,
 ): $ReadOnlyArray<ChatThreadItem> {
   const threadInfos = useSelector(threadInfoSelector);
   const messageInfos = useSelector(messageInfoSelector);
   const sidebarInfos = useSelector(sidebarInfoSelector);
   const messageStore = useSelector(state => state.messageStore);
 
   return React.useMemo(
     () =>
       getChatThreadItems(
         threadInfos,
         messageStore,
         messageInfos,
         sidebarInfos,
         filterFunction,
       ),
     [messageInfos, messageStore, sidebarInfos, filterFunction, threadInfos],
   );
 }
 
 function getChatThreadItems(
   threadInfos: { +[id: string]: ThreadInfo },
   messageStore: MessageStore,
   messageInfos: { +[id: string]: ?MessageInfo },
   sidebarInfos: { +[id: string]: $ReadOnlyArray<SidebarInfo> },
   filterFunction: (threadInfo: ?(ThreadInfo | RawThreadInfo)) => boolean,
 ): $ReadOnlyArray<ChatThreadItem> {
   return _flow(
     _filter(filterFunction),
     _map((threadInfo: ThreadInfo): ChatThreadItem =>
       createChatThreadItem(
         threadInfo,
         messageStore,
         messageInfos,
         sidebarInfos[threadInfo.id],
       ),
     ),
     _orderBy('lastUpdatedTimeIncludingSidebars')('desc'),
   )(threadInfos);
 }
 
 export type RobotextChatMessageInfoItem = {
   +itemType: 'message',
+  +messageInfoType: 'robotext',
   +messageInfo: RobotextMessageInfo,
   +startsConversation: boolean,
   +startsCluster: boolean,
   endsCluster: boolean,
   +robotext: string,
   +threadCreatedFromMessage: ?ThreadInfo,
   +reactions: $ReadOnlyMap<string, MessageReactionInfo>,
 };
 export type ChatMessageInfoItem =
   | RobotextChatMessageInfoItem
   | {
       +itemType: 'message',
+      +messageInfoType: 'composable',
       +messageInfo: ComposableMessageInfo,
       +localMessageInfo: ?LocalMessageInfo,
       +startsConversation: boolean,
       +startsCluster: boolean,
       endsCluster: boolean,
       +threadCreatedFromMessage: ?ThreadInfo,
       +reactions: $ReadOnlyMap<string, MessageReactionInfo>,
     };
 export type ChatMessageItem = { itemType: 'loader' } | ChatMessageInfoItem;
 export type MessageReactionInfo = {
   +viewerReacted: boolean,
   +users: $ReadOnlyArray<RelativeUserInfo>,
 };
 type TargetMessageReactions = Map<string, Map<string, RelativeUserInfo>>;
 
 const msInFiveMinutes = 5 * 60 * 1000;
 function createChatMessageItems(
   threadID: string,
   messageStore: MessageStore,
   messageInfos: { +[id: string]: ?MessageInfo },
   threadInfos: { +[id: string]: ThreadInfo },
   threadInfoFromSourceMessageID: { +[id: string]: ThreadInfo },
   additionalMessages: $ReadOnlyArray<MessageInfo>,
   viewerID: string,
 ): ChatMessageItem[] {
   const thread = messageStore.threads[threadID];
 
   const threadMessageInfos = (thread?.messageIDs ?? [])
     .map((messageID: string) => messageInfos[messageID])
     .filter(Boolean);
   const messages =
     additionalMessages.length > 0
       ? sortMessageInfoList([...threadMessageInfos, ...additionalMessages])
       : threadMessageInfos;
 
   const targetMessageReactionsMap = new Map<string, TargetMessageReactions>();
 
   // We need to iterate backwards to put the order of messages in chronological
   // order, starting with the oldest. This avoids the scenario where the most
   // recent message with the remove_reaction action may try to remove a user
   // that hasn't been added to the messageReactionUsersInfoMap, causing it
   // to be skipped.
   for (let i = messages.length - 1; i >= 0; i--) {
     const messageInfo = messages[i];
     if (messageInfo.type !== messageTypes.REACTION) {
       continue;
     }
 
     if (!targetMessageReactionsMap.has(messageInfo.targetMessageID)) {
       const reactsMap: TargetMessageReactions = new Map();
       targetMessageReactionsMap.set(messageInfo.targetMessageID, reactsMap);
     }
 
     const messageReactsMap = targetMessageReactionsMap.get(
       messageInfo.targetMessageID,
     );
     invariant(messageReactsMap, 'messageReactsInfo should be set');
 
     if (!messageReactsMap.has(messageInfo.reaction)) {
       const usersInfoMap = new Map<string, RelativeUserInfo>();
       messageReactsMap.set(messageInfo.reaction, usersInfoMap);
     }
 
     const messageReactionUsersInfoMap = messageReactsMap.get(
       messageInfo.reaction,
     );
     invariant(
       messageReactionUsersInfoMap,
       'messageReactionUsersInfoMap should be set',
     );
 
     if (messageInfo.action === 'add_reaction') {
       messageReactionUsersInfoMap.set(
         messageInfo.creator.id,
         messageInfo.creator,
       );
     } else {
       messageReactionUsersInfoMap.delete(messageInfo.creator.id);
     }
   }
 
   const chatMessageItems = [];
   let lastMessageInfo = null;
   for (let i = messages.length - 1; i >= 0; i--) {
     const messageInfo = messages[i];
 
     if (messageInfo.type === messageTypes.REACTION) {
       continue;
     }
 
     const originalMessageInfo =
       messageInfo.type === messageTypes.SIDEBAR_SOURCE
         ? messageInfo.sourceMessage
         : messageInfo;
 
     if (isEmptyMediaMessage(originalMessageInfo)) {
       continue;
     }
 
     let startsConversation = true;
     let startsCluster = true;
     if (
       lastMessageInfo &&
       lastMessageInfo.time + msInFiveMinutes > originalMessageInfo.time
     ) {
       startsConversation = false;
       if (
         isComposableMessageType(lastMessageInfo.type) &&
         isComposableMessageType(originalMessageInfo.type) &&
         lastMessageInfo.creator.id === originalMessageInfo.creator.id
       ) {
         startsCluster = false;
       }
     }
     if (startsCluster && chatMessageItems.length > 0) {
       const lastMessageItem = chatMessageItems[chatMessageItems.length - 1];
       invariant(lastMessageItem.itemType === 'message', 'should be message');
       lastMessageItem.endsCluster = true;
     }
     const threadCreatedFromMessage =
       messageInfo.id && threadInfos[threadID]?.type !== threadTypes.SIDEBAR
         ? threadInfoFromSourceMessageID[messageInfo.id]
         : undefined;
 
     const renderedReactions: $ReadOnlyMap<
       string,
       MessageReactionInfo,
     > = (() => {
       const result = new Map<string, MessageReactionInfo>();
 
       let messageReactsMap;
       if (originalMessageInfo.id) {
         messageReactsMap = targetMessageReactionsMap.get(
           originalMessageInfo.id,
         );
       }
 
       if (!messageReactsMap) {
         return result;
       }
 
       for (const reaction of messageReactsMap.keys()) {
         const reactionUsersInfoMap = messageReactsMap.get(reaction);
         invariant(reactionUsersInfoMap, 'reactionUsersInfoMap should be set');
 
         if (reactionUsersInfoMap.size === 0) {
           continue;
         }
 
         const reactionUserInfos = [...reactionUsersInfoMap.values()];
 
         const messageReactionInfo = {
           users: reactionUserInfos,
           viewerReacted: reactionUsersInfoMap.has(viewerID),
         };
 
         result.set(reaction, messageReactionInfo);
       }
 
       return result;
     })();
 
     if (isComposableMessageType(originalMessageInfo.type)) {
       // We use these invariants instead of just checking the messageInfo.type
       // directly in the conditional above so that isComposableMessageType can
       // be the source of truth
       invariant(
         originalMessageInfo.type === messageTypes.TEXT ||
           originalMessageInfo.type === messageTypes.IMAGES ||
           originalMessageInfo.type === messageTypes.MULTIMEDIA,
         "Flow doesn't understand isComposableMessageType above",
       );
       const localMessageInfo =
         messageStore.local[messageKey(originalMessageInfo)];
       chatMessageItems.push({
         itemType: 'message',
+        messageInfoType: 'composable',
         messageInfo: originalMessageInfo,
         localMessageInfo,
         startsConversation,
         startsCluster,
         endsCluster: false,
         threadCreatedFromMessage,
         reactions: renderedReactions,
       });
     } else {
       invariant(
         originalMessageInfo.type !== messageTypes.TEXT &&
           originalMessageInfo.type !== messageTypes.IMAGES &&
           originalMessageInfo.type !== messageTypes.MULTIMEDIA,
         "Flow doesn't understand isComposableMessageType above",
       );
       const robotext = robotextForMessageInfo(
         originalMessageInfo,
         threadInfos[threadID],
       );
       chatMessageItems.push({
         itemType: 'message',
+        messageInfoType: 'robotext',
         messageInfo: originalMessageInfo,
         startsConversation,
         startsCluster,
         endsCluster: false,
         threadCreatedFromMessage,
         robotext,
         reactions: renderedReactions,
       });
     }
     lastMessageInfo = originalMessageInfo;
   }
   if (chatMessageItems.length > 0) {
     const lastMessageItem = chatMessageItems[chatMessageItems.length - 1];
     invariant(lastMessageItem.itemType === 'message', 'should be message');
     lastMessageItem.endsCluster = true;
   }
   chatMessageItems.reverse();
   const hideSpinner = thread ? thread.startReached : threadIsPending(threadID);
   if (hideSpinner) {
     return chatMessageItems;
   }
   return [...chatMessageItems, ({ itemType: 'loader' }: ChatMessageItem)];
 }
 
 const baseMessageListData = (
   threadID: ?string,
   additionalMessages: $ReadOnlyArray<MessageInfo>,
 ) =>
   createSelector(
     (state: BaseAppState<*>) => state.messageStore,
     messageInfoSelector,
     threadInfoSelector,
     threadInfoFromSourceMessageIDSelector,
     (state: BaseAppState<*>) =>
       state.currentUserInfo && state.currentUserInfo.id,
     (
       messageStore: MessageStore,
       messageInfos: { +[id: string]: ?MessageInfo },
       threadInfos: { +[id: string]: ThreadInfo },
       threadInfoFromSourceMessageID: { +[id: string]: ThreadInfo },
       viewerID: ?string,
     ): ?(ChatMessageItem[]) => {
       if (!threadID || !viewerID) {
         return null;
       }
       return createChatMessageItems(
         threadID,
         messageStore,
         messageInfos,
         threadInfos,
         threadInfoFromSourceMessageID,
         additionalMessages,
         viewerID,
       );
     },
   );
 type MessageListData = ?(ChatMessageItem[]);
 const messageListData: (
   threadID: ?string,
   additionalMessages: $ReadOnlyArray<MessageInfo>,
 ) => (state: BaseAppState<*>) => MessageListData = memoize2(
   baseMessageListData,
 );
 
 type UseMessageListDataArgs = {
   +searching: boolean,
   +userInfoInputArray: $ReadOnlyArray<AccountUserInfo>,
   +threadInfo: ?ThreadInfo,
 };
 
 function useMessageListData({
   searching,
   userInfoInputArray,
   threadInfo,
 }: UseMessageListDataArgs): MessageListData {
   const pendingSidebarSourceMessageInfo = useSelector(state => {
     const sourceMessageID = threadInfo?.sourceMessageID;
     if (
       !threadInfo ||
       threadInfo.type !== threadTypes.SIDEBAR ||
       !sourceMessageID
     ) {
       return null;
     }
     const thread = state.messageStore.threads[threadInfo.id];
     const messageInfos = messageInfoSelector(state);
     const shouldSourceBeAdded =
       !thread ||
       (thread.startReached &&
         thread.messageIDs.every(
           id => messageInfos[id]?.type !== messageTypes.SIDEBAR_SOURCE,
         ));
     return shouldSourceBeAdded ? messageInfos[sourceMessageID] : null;
   });
 
   invariant(
     !pendingSidebarSourceMessageInfo ||
       pendingSidebarSourceMessageInfo.type !== messageTypes.SIDEBAR_SOURCE,
     'sidebars can not be created from sidebar_source message',
   );
 
   const additionalMessages = React.useMemo(
     () =>
       pendingSidebarSourceMessageInfo ? [pendingSidebarSourceMessageInfo] : [],
     [pendingSidebarSourceMessageInfo],
   );
   const boundMessageListData = useSelector(
     messageListData(threadInfo?.id, additionalMessages),
   );
 
   return React.useMemo(() => {
     if (searching && userInfoInputArray.length === 0) {
       return [];
     }
     return boundMessageListData;
   }, [searching, userInfoInputArray.length, boundMessageListData]);
 }
 
 export {
   messageInfoSelector,
   createChatThreadItem,
   chatListData,
   createChatMessageItems,
   messageListData,
   useFlattenedChatListData,
   useFilteredChatListData,
   useMessageListData,
 };
diff --git a/native/chat/chat-item-height-measurer.react.js b/native/chat/chat-item-height-measurer.react.js
index 6314ae598..1e6bf937a 100644
--- a/native/chat/chat-item-height-measurer.react.js
+++ b/native/chat/chat-item-height-measurer.react.js
@@ -1,170 +1,175 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 
 import type { ChatMessageItem } from 'lib/selectors/chat-selectors';
 import { messageID } from 'lib/shared/message-utils';
 import { messageTypes, type MessageType } from 'lib/types/message-types';
 
 import NodeHeightMeasurer from '../components/node-height-measurer.react';
 import { InputStateContext } from '../input/input-state';
 import type { MeasurementTask } from './chat-context-provider.react';
 import { useComposedMessageMaxWidth } from './composed-message-width';
 import { dummyNodeForRobotextMessageHeightMeasurement } from './inner-robotext-message.react';
 import { dummyNodeForTextMessageHeightMeasurement } from './inner-text-message.react';
 import { MessageListContextProvider } from './message-list-types';
 import { multimediaMessageContentSizes } from './multimedia-message-utils';
 import { chatMessageItemKey } from './utils';
 
 type Props = {
   +measurement: MeasurementTask,
 };
 
 const heightMeasurerKey = (item: ChatMessageItem) => {
   if (item.itemType !== 'message') {
     return null;
   }
   const { messageInfo } = item;
   if (messageInfo.type === messageTypes.TEXT) {
     return messageInfo.text;
   } else if (item.robotext && typeof item.robotext === 'string') {
     return item.robotext;
   }
   return null;
 };
 
 const heightMeasurerDummy = (item: ChatMessageItem) => {
   invariant(
     item.itemType === 'message',
     'NodeHeightMeasurer asked for dummy for non-message item',
   );
   const { messageInfo } = item;
   if (messageInfo.type === messageTypes.TEXT) {
     return dummyNodeForTextMessageHeightMeasurement(messageInfo.text);
   } else if (item.robotext && typeof item.robotext === 'string') {
     return dummyNodeForRobotextMessageHeightMeasurement(item.robotext);
   }
   invariant(false, 'NodeHeightMeasurer asked for dummy for non-text message');
 };
 
 function ChatItemHeightMeasurer(props: Props) {
   const composedMessageMaxWidth = useComposedMessageMaxWidth();
   const inputState = React.useContext(InputStateContext);
   const inputStatePendingUploads = inputState?.pendingUploads;
 
   const { measurement } = props;
   const { threadInfo } = measurement;
   const heightMeasurerMergeItem = React.useCallback(
     (item: ChatMessageItem, height: ?number) => {
       if (item.itemType !== 'message') {
         return item;
       }
 
       const { messageInfo } = item;
       const messageType: MessageType = messageInfo.type;
       invariant(
         messageType !== messageTypes.SIDEBAR_SOURCE,
         'Sidebar source messages should be replaced by sourceMessage before being measured',
       );
 
       if (
         messageInfo.type === messageTypes.IMAGES ||
         messageInfo.type === messageTypes.MULTIMEDIA
       ) {
         // Conditional due to Flow...
         const localMessageInfo = item.localMessageInfo
           ? item.localMessageInfo
           : null;
         const id = messageID(messageInfo);
         const pendingUploads = inputStatePendingUploads?.[id];
         const sizes = multimediaMessageContentSizes(
           messageInfo,
           composedMessageMaxWidth,
         );
         return {
           itemType: 'message',
           messageShapeType: 'multimedia',
           messageInfo,
           localMessageInfo,
           threadInfo,
           startsConversation: item.startsConversation,
           startsCluster: item.startsCluster,
           endsCluster: item.endsCluster,
           threadCreatedFromMessage: item.threadCreatedFromMessage,
           pendingUploads,
           reactions: item.reactions,
           ...sizes,
         };
       }
 
       invariant(
         height !== null && height !== undefined,
         'height should be set',
       );
       if (messageInfo.type === messageTypes.TEXT) {
         // Conditional due to Flow...
         const localMessageInfo = item.localMessageInfo
           ? item.localMessageInfo
           : null;
         return {
           itemType: 'message',
           messageShapeType: 'text',
           messageInfo,
           localMessageInfo,
           threadInfo,
           startsConversation: item.startsConversation,
           startsCluster: item.startsCluster,
           endsCluster: item.endsCluster,
           threadCreatedFromMessage: item.threadCreatedFromMessage,
           contentHeight: height,
           reactions: item.reactions,
         };
-      } else {
-        invariant(
-          typeof item.robotext === 'string',
-          "Flow can't handle our fancy types :(",
-        );
-        return {
-          itemType: 'message',
-          messageShapeType: 'robotext',
-          messageInfo,
-          threadInfo,
-          startsConversation: item.startsConversation,
-          startsCluster: item.startsCluster,
-          endsCluster: item.endsCluster,
-          threadCreatedFromMessage: item.threadCreatedFromMessage,
-          robotext: item.robotext,
-          contentHeight: height,
-          reactions: item.reactions,
-        };
       }
+      invariant(
+        item.messageInfoType !== 'composable',
+        'ChatItemHeightMeasurer was handed a messageInfoType=composable, but ' +
+          `does not know how to handle MessageType ${messageInfo.type}`,
+      );
+      invariant(
+        item.messageInfoType === 'robotext',
+        'ChatItemHeightMeasurer was handed a messageInfoType that it does ' +
+          `not recognize: ${item.messageInfoType}`,
+      );
+      return {
+        itemType: 'message',
+        messageShapeType: 'robotext',
+        messageInfo,
+        threadInfo,
+        startsConversation: item.startsConversation,
+        startsCluster: item.startsCluster,
+        endsCluster: item.endsCluster,
+        threadCreatedFromMessage: item.threadCreatedFromMessage,
+        robotext: item.robotext,
+        contentHeight: height,
+        reactions: item.reactions,
+      };
     },
     [composedMessageMaxWidth, inputStatePendingUploads, threadInfo],
   );
 
   return (
     <MessageListContextProvider
       threadID={threadInfo.id}
       key={measurement.measurerID}
     >
       <NodeHeightMeasurer
         listData={measurement.messages}
         itemToID={chatMessageItemKey}
         itemToMeasureKey={heightMeasurerKey}
         itemToDummy={heightMeasurerDummy}
         mergeItemWithHeight={heightMeasurerMergeItem}
         allHeightsMeasured={measurement.onMessagesMeasured}
         inputState={inputState}
         composedMessageMaxWidth={composedMessageMaxWidth}
         initialMeasuredHeights={measurement.initialMeasuredHeights}
       />
     </MessageListContextProvider>
   );
 }
 
 const MemoizedChatItemHeightMeasurer: React.ComponentType<Props> = React.memo<Props>(
   ChatItemHeightMeasurer,
 );
 
 export default MemoizedChatItemHeightMeasurer;