diff --git a/lib/shared/messages/reaction-message-spec.js b/lib/shared/messages/reaction-message-spec.js
index cc5e1905b..74f024d7a 100644
--- a/lib/shared/messages/reaction-message-spec.js
+++ b/lib/shared/messages/reaction-message-spec.js
@@ -1,197 +1,206 @@
 // @flow
 
 import invariant from 'invariant';
 
 import type { PlatformDetails } from '../../types/device-types';
 import {
   assertMessageType,
   messageTypes,
   type MessageInfo,
   type ClientDBMessageInfo,
   type ReactionMessageData,
   type RawReactionMessageInfo,
   type ReactionMessageInfo,
 } from '../../types/message-types';
 import type { RawUnsupportedMessageInfo } from '../../types/messages/unsupported';
 import type { NotifTexts } from '../../types/notif-types';
 import type { ThreadInfo } from '../../types/thread-types';
 import type { RelativeUserInfo } from '../../types/user-types';
 import { messagePreviewText, removeCreatorAsViewer } from '../message-utils';
 import { threadIsGroupChat } from '../thread-utils';
 import { stringForUser } from '../user-utils';
 import { hasMinCodeVersion } from '../version-utils';
 import type {
   MessageSpec,
   MessageTitleParam,
   NotificationTextsParams,
 } from './message-spec';
-import { assertSingleMessageInfo } from './utils';
+import { assertSingleMessageInfo, joinResult } from './utils';
 
 export const reactionMessageSpec: MessageSpec<
   ReactionMessageData,
   RawReactionMessageInfo,
   ReactionMessageInfo,
 > = Object.freeze({
   messageContentForServerDB(
     data: ReactionMessageData | RawReactionMessageInfo,
   ): string {
     return JSON.stringify({
       reaction: data.reaction,
       action: data.action,
     });
   },
 
   messageContentForClientDB(data: RawReactionMessageInfo): string {
     return JSON.stringify({
       targetMessageID: data.targetMessageID,
       reaction: data.reaction,
       action: data.action,
     });
   },
 
   messageTitle({
     messageInfo,
     threadInfo,
     viewerContext,
   }: MessageTitleParam<ReactionMessageInfo>) {
     let validMessageInfo: ReactionMessageInfo = (messageInfo: ReactionMessageInfo);
     if (viewerContext === 'global_viewer') {
       validMessageInfo = removeCreatorAsViewer(validMessageInfo);
     }
     return messagePreviewText(validMessageInfo, threadInfo);
   },
 
   rawMessageInfoFromServerDBRow(row: Object): RawReactionMessageInfo {
     invariant(
       row.targetMessageID !== null && row.targetMessageID !== undefined,
       'targetMessageID should be set',
     );
 
     const content = JSON.parse(row.content);
 
     return {
       type: messageTypes.REACTION,
       id: row.id.toString(),
       threadID: row.threadID.toString(),
       time: row.time,
       creatorID: row.creatorID.toString(),
       targetMessageID: row.targetMessageID.toString(),
       reaction: content.reaction,
       action: content.action,
     };
   },
 
   rawMessageInfoFromClientDB(
     clientDBMessageInfo: ClientDBMessageInfo,
   ): RawReactionMessageInfo {
     const messageType = assertMessageType(parseInt(clientDBMessageInfo.type));
     invariant(
       messageType === messageTypes.REACTION,
       'message must be of type REACTION',
     );
     invariant(
       clientDBMessageInfo.content !== undefined &&
         clientDBMessageInfo.content !== null,
       'content must be defined',
     );
     const content = JSON.parse(clientDBMessageInfo.content);
 
     const rawReactionMessageInfo: RawReactionMessageInfo = {
       type: messageTypes.REACTION,
       id: clientDBMessageInfo.id,
       threadID: clientDBMessageInfo.thread,
       time: parseInt(clientDBMessageInfo.time),
       creatorID: clientDBMessageInfo.user,
       targetMessageID: content.targetMessageID,
       reaction: content.reaction,
       action: content.action,
     };
 
     return rawReactionMessageInfo;
   },
 
   createMessageInfo(
     rawMessageInfo: RawReactionMessageInfo,
     creator: RelativeUserInfo,
   ): ReactionMessageInfo {
     return {
       type: messageTypes.REACTION,
       id: rawMessageInfo.id,
       threadID: rawMessageInfo.threadID,
       creator,
       time: rawMessageInfo.time,
       targetMessageID: rawMessageInfo.targetMessageID,
       reaction: rawMessageInfo.reaction,
       action: rawMessageInfo.action,
     };
   },
 
   rawMessageInfoFromMessageData(
     messageData: ReactionMessageData,
     id: ?string,
   ): RawReactionMessageInfo {
     invariant(id, 'RawReactionMessageInfo needs id');
     return { ...messageData, id };
   },
 
   shimUnsupportedMessageInfo(
     rawMessageInfo: RawReactionMessageInfo,
     platformDetails: ?PlatformDetails,
   ): RawReactionMessageInfo | RawUnsupportedMessageInfo {
     // TODO: change minCodeVersion to correct number when ready
     if (hasMinCodeVersion(platformDetails, 999)) {
       return rawMessageInfo;
     }
     const { id } = rawMessageInfo;
     invariant(id !== null && id !== undefined, 'id should be set on server');
 
     return {
       type: messageTypes.UNSUPPORTED,
       id,
       threadID: rawMessageInfo.threadID,
       creatorID: rawMessageInfo.creatorID,
       time: rawMessageInfo.time,
       robotext: 'liked a message',
       unsupportedMessageInfo: rawMessageInfo,
     };
   },
 
   unshimMessageInfo(unwrapped: RawReactionMessageInfo): RawReactionMessageInfo {
     return unwrapped;
   },
 
   notificationTexts(
     messageInfos: $ReadOnlyArray<MessageInfo>,
     threadInfo: ThreadInfo,
     params: NotificationTextsParams,
   ): NotifTexts {
     const messageInfo = assertSingleMessageInfo(messageInfos);
     invariant(
       messageInfo.type === messageTypes.REACTION,
       'messageInfo should be reaction type',
     );
 
     const userString = stringForUser(messageInfo.creator);
     const body =
       messageInfo.action === 'add_reaction'
         ? 'liked a message'
         : 'unliked a message';
 
     let merged;
     if (!threadInfo.name && !threadIsGroupChat(threadInfo)) {
       merged = `${userString} ${body}`;
     } else {
       const threadName = params.notifThreadName(threadInfo);
       merged = `${userString} ${body} in ${threadName}`;
     }
 
     return {
       merged,
       body,
       title: threadInfo.uiName,
       prefix: userString,
     };
   },
 
+  notificationCollapseKey(rawMessageInfo: RawReactionMessageInfo): string {
+    return joinResult(
+      rawMessageInfo.type,
+      rawMessageInfo.threadID,
+      rawMessageInfo.creatorID,
+      rawMessageInfo.targetMessageID,
+    );
+  },
+
   generatesNotifs: true,
 });