diff --git a/lib/shared/messages/create-sidebar-message-spec.js b/lib/shared/messages/create-sidebar-message-spec.js
index 6597c8ff5..418f40157 100644
--- a/lib/shared/messages/create-sidebar-message-spec.js
+++ b/lib/shared/messages/create-sidebar-message-spec.js
@@ -1,215 +1,217 @@
 // @flow
 
 import invariant from 'invariant';
 
 import type { PlatformDetails } from '../../types/device-types';
 import { messageTypes } from '../../types/message-types';
 import type { MessageInfo } from '../../types/message-types';
 import type {
   CreateSidebarMessageData,
   CreateSidebarMessageInfo,
   RawCreateSidebarMessageInfo,
 } from '../../types/messages/create-sidebar';
 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 {
   robotextToRawString,
   robotextForMessageInfo,
   removeCreatorAsViewer,
 } from '../message-utils';
 import { stringForUser } from '../user-utils';
 import { hasMinCodeVersion } from '../version-utils';
 import type {
   CreateMessageInfoParams,
   MessageSpec,
   MessageTitleParam,
   RobotextParams,
 } from './message-spec';
 import { assertSingleMessageInfo } from './utils';
 
 export const createSidebarMessageSpec: MessageSpec<
   CreateSidebarMessageData,
   RawCreateSidebarMessageInfo,
   CreateSidebarMessageInfo,
 > = Object.freeze({
   messageContent(data: CreateSidebarMessageData): string {
     return JSON.stringify({
       ...data.initialThreadState,
       sourceMessageAuthorID: data.sourceMessageAuthorID,
     });
   },
 
   messageTitle({
     messageInfo,
     threadInfo,
     viewerContext,
   }: MessageTitleParam<CreateSidebarMessageInfo>) {
     let validMessageInfo: CreateSidebarMessageInfo = (messageInfo: CreateSidebarMessageInfo);
     if (viewerContext === 'global_viewer') {
       validMessageInfo = removeCreatorAsViewer(validMessageInfo);
       validMessageInfo = {
         ...validMessageInfo,
         sourceMessageAuthor: {
           ...validMessageInfo.sourceMessageAuthor,
           isViewer: false,
         },
         initialThreadState: {
           ...validMessageInfo.initialThreadState,
           otherMembers: validMessageInfo.initialThreadState.otherMembers.map(
             (item) => ({
               ...item,
               isViewer: false,
             }),
           ),
         },
       };
     }
     return robotextToRawString(
       robotextForMessageInfo(validMessageInfo, threadInfo),
     );
   },
 
   rawMessageInfoFromRow(row: Object): RawCreateSidebarMessageInfo {
     const { sourceMessageAuthorID, ...initialThreadState } = JSON.parse(
       row.content,
     );
     return {
       type: messageTypes.CREATE_SIDEBAR,
       id: row.id.toString(),
       threadID: row.threadID.toString(),
       time: row.time,
       creatorID: row.creatorID.toString(),
       sourceMessageAuthorID,
       initialThreadState,
     };
   },
 
   createMessageInfo(
     rawMessageInfo: RawCreateSidebarMessageInfo,
     creator: RelativeUserInfo,
     params: CreateMessageInfoParams,
   ): ?CreateSidebarMessageInfo {
     const { threadInfos } = params;
     const parentThreadInfo =
       threadInfos[rawMessageInfo.initialThreadState.parentThreadID];
 
     const sourceMessageAuthor = params.createRelativeUserInfos([
       rawMessageInfo.sourceMessageAuthorID,
     ])[0];
     if (!sourceMessageAuthor) {
       return null;
     }
 
     return {
       type: messageTypes.CREATE_SIDEBAR,
       id: rawMessageInfo.id,
       threadID: rawMessageInfo.threadID,
       creator,
       time: rawMessageInfo.time,
       sourceMessageAuthor,
       initialThreadState: {
         name: rawMessageInfo.initialThreadState.name,
         parentThreadInfo,
         color: rawMessageInfo.initialThreadState.color,
         otherMembers: params.createRelativeUserInfos(
           rawMessageInfo.initialThreadState.memberIDs.filter(
             (userID: string) => userID !== rawMessageInfo.creatorID,
           ),
         ),
       },
     };
   },
 
   rawMessageInfoFromMessageData(
     messageData: CreateSidebarMessageData,
     id: string,
   ): RawCreateSidebarMessageInfo {
     return { ...messageData, id };
   },
 
   robotext(
     messageInfo: CreateSidebarMessageInfo,
     creator: string,
     params: RobotextParams,
   ): string {
     let text = `started ${params.encodedThreadEntity(
       messageInfo.threadID,
       `this sidebar`,
     )}`;
     const users = messageInfo.initialThreadState.otherMembers.filter(
       (member) => member.id !== messageInfo.sourceMessageAuthor.id,
     );
     if (users.length !== 0) {
       const initialUsersString = params.robotextForUsers(users);
       text += ` and added ${initialUsersString}`;
     }
     return `${creator} ${text}`;
   },
 
   shimUnsupportedMessageInfo(
     rawMessageInfo: RawCreateSidebarMessageInfo,
     platformDetails: ?PlatformDetails,
   ): RawCreateSidebarMessageInfo | RawUnsupportedMessageInfo {
     // TODO determine min code version
     if (hasMinCodeVersion(platformDetails, 75)) {
       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: 'created a sidebar',
       unsupportedMessageInfo: rawMessageInfo,
     };
   },
 
   unshimMessageInfo(
     unwrapped: RawCreateSidebarMessageInfo,
   ): RawCreateSidebarMessageInfo {
     return unwrapped;
   },
 
   notificationTexts(
     messageInfos: $ReadOnlyArray<MessageInfo>,
     threadInfo: ThreadInfo,
   ): NotifTexts {
     const messageInfo = assertSingleMessageInfo(messageInfos);
     invariant(
       messageInfo.type === messageTypes.CREATE_SIDEBAR,
       'messageInfo should be messageTypes.CREATE_SIDEBAR!',
     );
     const prefix = stringForUser(messageInfo.creator);
     const title = threadInfo.uiName;
     const sourceMessageAuthorPossessive = messageInfo.sourceMessageAuthor
       .isViewer
       ? 'your'
       : `${stringForUser(messageInfo.sourceMessageAuthor)}'s`;
     const body =
       `started a sidebar in response to ${sourceMessageAuthorPossessive} ` +
       `message "${messageInfo.initialThreadState.name ?? ''}"`;
     const merged = `${prefix} ${body}`;
     return {
       merged,
       body,
       title,
       prefix,
     };
   },
 
   generatesNotifs: true,
 
   userIDs(rawMessageInfo: RawCreateSidebarMessageInfo): $ReadOnlyArray<string> {
     return rawMessageInfo.initialThreadState.memberIDs;
   },
 
-  threadIDs(rawMessageInfo) {
+  threadIDs(
+    rawMessageInfo: RawCreateSidebarMessageInfo,
+  ): $ReadOnlyArray<string> {
     const { parentThreadID } = rawMessageInfo.initialThreadState;
     return [parentThreadID];
   },
 });
diff --git a/lib/shared/messages/create-sub-thread-message-spec.js b/lib/shared/messages/create-sub-thread-message-spec.js
index 5e68ca40e..95d0ac1f2 100644
--- a/lib/shared/messages/create-sub-thread-message-spec.js
+++ b/lib/shared/messages/create-sub-thread-message-spec.js
@@ -1,138 +1,140 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { permissionLookup } from '../../permissions/thread-permissions';
 import { messageTypes } from '../../types/message-types';
 import type { MessageInfo } from '../../types/message-types';
 import type {
   CreateSubthreadMessageData,
   CreateSubthreadMessageInfo,
   RawCreateSubthreadMessageInfo,
 } from '../../types/messages/create-subthread';
 import type { NotifTexts } from '../../types/notif-types';
 import { threadPermissions, threadTypes } from '../../types/thread-types';
 import type { ThreadInfo } from '../../types/thread-types';
 import type { RelativeUserInfo } from '../../types/user-types';
 import {
   robotextToRawString,
   robotextForMessageInfo,
   removeCreatorAsViewer,
 } from '../message-utils';
 import type {
   CreateMessageInfoParams,
   MessageSpec,
   MessageTitleParam,
   NotificationTextsParams,
 } from './message-spec';
 import { assertSingleMessageInfo } from './utils';
 
 export const createSubThreadMessageSpec: MessageSpec<
   CreateSubthreadMessageData,
   RawCreateSubthreadMessageInfo,
   CreateSubthreadMessageInfo,
 > = Object.freeze({
   messageContent(data: CreateSubthreadMessageData): string {
     return data.childThreadID;
   },
 
   messageTitle({
     messageInfo,
     threadInfo,
     viewerContext,
   }: MessageTitleParam<CreateSubthreadMessageInfo>) {
     let validMessageInfo: CreateSubthreadMessageInfo = (messageInfo: CreateSubthreadMessageInfo);
     if (viewerContext === 'global_viewer') {
       validMessageInfo = removeCreatorAsViewer(validMessageInfo);
     }
     return robotextToRawString(
       robotextForMessageInfo(validMessageInfo, threadInfo),
     );
   },
 
   rawMessageInfoFromRow(row: Object): ?RawCreateSubthreadMessageInfo {
     const subthreadPermissions = row.subthread_permissions;
     if (!permissionLookup(subthreadPermissions, threadPermissions.KNOW_OF)) {
       return null;
     }
     return {
       type: messageTypes.CREATE_SUB_THREAD,
       id: row.id.toString(),
       threadID: row.threadID.toString(),
       time: row.time,
       creatorID: row.creatorID.toString(),
       childThreadID: row.content,
     };
   },
 
   createMessageInfo(
     rawMessageInfo: RawCreateSubthreadMessageInfo,
     creator: RelativeUserInfo,
     params: CreateMessageInfoParams,
   ): ?CreateSubthreadMessageInfo {
     const { threadInfos } = params;
     const childThreadInfo = threadInfos[rawMessageInfo.childThreadID];
     if (!childThreadInfo) {
       return null;
     }
     return {
       type: messageTypes.CREATE_SUB_THREAD,
       id: rawMessageInfo.id,
       threadID: rawMessageInfo.threadID,
       creator,
       time: rawMessageInfo.time,
       childThreadInfo,
     };
   },
 
   rawMessageInfoFromMessageData(
     messageData: CreateSubthreadMessageData,
     id: string,
   ): RawCreateSubthreadMessageInfo {
     return { ...messageData, id };
   },
 
   robotext(messageInfo: CreateSubthreadMessageInfo, creator: string): string {
     const childName = messageInfo.childThreadInfo.name;
     const childNoun =
       messageInfo.childThreadInfo.type === threadTypes.SIDEBAR
         ? 'sidebar'
         : 'child thread';
     if (childName) {
       return (
         `${creator} created a ${childNoun}` +
         ` named "<${encodeURI(childName)}|t${messageInfo.childThreadInfo.id}>"`
       );
     } else {
       return (
         `${creator} created a ` +
         `<${childNoun}|t${messageInfo.childThreadInfo.id}>`
       );
     }
   },
 
   notificationTexts(
     messageInfos: $ReadOnlyArray<MessageInfo>,
     threadInfo: ThreadInfo,
     params: NotificationTextsParams,
   ): NotifTexts {
     const messageInfo = assertSingleMessageInfo(messageInfos);
     invariant(
       messageInfo.type === messageTypes.CREATE_SUB_THREAD,
       'messageInfo should be messageTypes.CREATE_SUB_THREAD!',
     );
     return params.notifTextForSubthreadCreation(
       messageInfo.creator,
       messageInfo.childThreadInfo.type,
       threadInfo,
       messageInfo.childThreadInfo.name,
       messageInfo.childThreadInfo.uiName,
     );
   },
 
   generatesNotifs: true,
 
-  threadIDs(rawMessageInfo) {
+  threadIDs(
+    rawMessageInfo: RawCreateSubthreadMessageInfo,
+  ): $ReadOnlyArray<string> {
     return [rawMessageInfo.childThreadID];
   },
 });
diff --git a/lib/shared/messages/create-thread-message-spec.js b/lib/shared/messages/create-thread-message-spec.js
index 4e472155c..0ab0ca78b 100644
--- a/lib/shared/messages/create-thread-message-spec.js
+++ b/lib/shared/messages/create-thread-message-spec.js
@@ -1,188 +1,190 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { messageTypes } from '../../types/message-types';
 import type { MessageInfo } from '../../types/message-types';
 import type {
   CreateThreadMessageData,
   CreateThreadMessageInfo,
   RawCreateThreadMessageInfo,
 } from '../../types/messages/create-thread';
 import type { NotifTexts } from '../../types/notif-types';
 import type { ThreadInfo } from '../../types/thread-types';
 import type { RelativeUserInfo } from '../../types/user-types';
 import {
   robotextToRawString,
   robotextForMessageInfo,
   removeCreatorAsViewer,
 } from '../message-utils';
 import { stringForUser } from '../user-utils';
 import type {
   CreateMessageInfoParams,
   MessageSpec,
   MessageTitleParam,
   NotificationTextsParams,
   RobotextParams,
 } from './message-spec';
 import { assertSingleMessageInfo } from './utils';
 
 export const createThreadMessageSpec: MessageSpec<
   CreateThreadMessageData,
   RawCreateThreadMessageInfo,
   CreateThreadMessageInfo,
 > = Object.freeze({
   messageContent(data: CreateThreadMessageData): string {
     return JSON.stringify(data.initialThreadState);
   },
 
   messageTitle({
     messageInfo,
     threadInfo,
     viewerContext,
   }: MessageTitleParam<CreateThreadMessageInfo>) {
     let validMessageInfo: CreateThreadMessageInfo = (messageInfo: CreateThreadMessageInfo);
     if (viewerContext === 'global_viewer') {
       validMessageInfo = removeCreatorAsViewer(validMessageInfo);
       validMessageInfo = {
         ...validMessageInfo,
         initialThreadState: {
           ...validMessageInfo.initialThreadState,
           otherMembers: validMessageInfo.initialThreadState.otherMembers.map(
             (item) => ({
               ...item,
               isViewer: false,
             }),
           ),
         },
       };
     }
     return robotextToRawString(
       robotextForMessageInfo(validMessageInfo, threadInfo),
     );
   },
 
   rawMessageInfoFromRow(row: Object): RawCreateThreadMessageInfo {
     return {
       type: messageTypes.CREATE_THREAD,
       id: row.id.toString(),
       threadID: row.threadID.toString(),
       time: row.time,
       creatorID: row.creatorID.toString(),
       initialThreadState: JSON.parse(row.content),
     };
   },
 
   createMessageInfo(
     rawMessageInfo: RawCreateThreadMessageInfo,
     creator: RelativeUserInfo,
     params: CreateMessageInfoParams,
   ): CreateThreadMessageInfo {
     const initialParentThreadID =
       rawMessageInfo.initialThreadState.parentThreadID;
     const parentThreadInfo = initialParentThreadID
       ? params.threadInfos[initialParentThreadID]
       : null;
 
     return {
       type: messageTypes.CREATE_THREAD,
       id: rawMessageInfo.id,
       threadID: rawMessageInfo.threadID,
       creator,
       time: rawMessageInfo.time,
       initialThreadState: {
         name: rawMessageInfo.initialThreadState.name,
         parentThreadInfo,
         type: rawMessageInfo.initialThreadState.type,
         color: rawMessageInfo.initialThreadState.color,
         otherMembers: params.createRelativeUserInfos(
           rawMessageInfo.initialThreadState.memberIDs.filter(
             (userID: string) => userID !== rawMessageInfo.creatorID,
           ),
         ),
       },
     };
   },
 
   rawMessageInfoFromMessageData(
     messageData: CreateThreadMessageData,
     id: string,
   ): RawCreateThreadMessageInfo {
     return { ...messageData, id };
   },
 
   robotext(
     messageInfo: CreateThreadMessageInfo,
     creator: string,
     params: RobotextParams,
   ): string {
     let text = `created ${params.encodedThreadEntity(
       messageInfo.threadID,
       `this thread`,
     )}`;
     const parentThread = messageInfo.initialThreadState.parentThreadInfo;
     if (parentThread) {
       text +=
         ' as a child of ' +
         `<${encodeURI(parentThread.uiName)}|t${parentThread.id}>`;
     }
     if (messageInfo.initialThreadState.name) {
       text += ` with the name "${encodeURI(
         messageInfo.initialThreadState.name,
       )}"`;
     }
     const users = messageInfo.initialThreadState.otherMembers;
     if (users.length !== 0) {
       const initialUsersString = params.robotextForUsers(users);
       text += ` and added ${initialUsersString}`;
     }
     return `${creator} ${text}`;
   },
 
   notificationTexts(
     messageInfos: $ReadOnlyArray<MessageInfo>,
     threadInfo: ThreadInfo,
     params: NotificationTextsParams,
   ): NotifTexts {
     const messageInfo = assertSingleMessageInfo(messageInfos);
     invariant(
       messageInfo.type === messageTypes.CREATE_THREAD,
       'messageInfo should be messageTypes.CREATE_THREAD!',
     );
     const parentThreadInfo = messageInfo.initialThreadState.parentThreadInfo;
     if (parentThreadInfo) {
       return params.notifTextForSubthreadCreation(
         messageInfo.creator,
         messageInfo.initialThreadState.type,
         parentThreadInfo,
         messageInfo.initialThreadState.name,
         threadInfo.uiName,
       );
     }
     const prefix = stringForUser(messageInfo.creator);
     const body = 'created a new thread';
     let merged = `${prefix} ${body}`;
     if (messageInfo.initialThreadState.name) {
       merged += ` called "${messageInfo.initialThreadState.name}"`;
     }
     return {
       merged,
       body,
       title: threadInfo.uiName,
       prefix,
     };
   },
 
   generatesNotifs: true,
 
   userIDs(rawMessageInfo: RawCreateThreadMessageInfo): $ReadOnlyArray<string> {
     return rawMessageInfo.initialThreadState.memberIDs;
   },
 
   startsThread: true,
 
-  threadIDs(rawMessageInfo) {
+  threadIDs(
+    rawMessageInfo: RawCreateThreadMessageInfo,
+  ): $ReadOnlyArray<string> {
     const { parentThreadID } = rawMessageInfo.initialThreadState;
     return parentThreadID ? [parentThreadID] : [];
   },
 });