diff --git a/keyserver/src/updaters/thread-updaters.js b/keyserver/src/updaters/thread-updaters.js
index 9afe8b685..c11e34021 100644
--- a/keyserver/src/updaters/thread-updaters.js
+++ b/keyserver/src/updaters/thread-updaters.js
@@ -1,849 +1,853 @@
 // @flow
 
 import { filteredThreadIDs } from 'lib/selectors/calendar-filter-selectors.js';
 import {
   threadHasAdminRole,
   roleIsAdminRole,
   viewerIsMember,
   getThreadTypeParentRequirement,
+  validChatNameRegex,
 } from 'lib/shared/thread-utils.js';
 import { hasMinCodeVersion } from 'lib/shared/version-utils.js';
 import type { Shape } from 'lib/types/core.js';
 import {
   messageTypes,
   defaultNumberPerThread,
 } from 'lib/types/message-types.js';
 import {
   type RoleChangeRequest,
   type ChangeThreadSettingsResult,
   type RemoveMembersRequest,
   type LeaveThreadRequest,
   type LeaveThreadResult,
   type UpdateThreadRequest,
   type ServerThreadJoinRequest,
   type ThreadJoinResult,
   threadPermissions,
   threadTypes,
 } from 'lib/types/thread-types.js';
 import { updateTypes } from 'lib/types/update-types.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { promiseAll } from 'lib/utils/promises.js';
 import { firstLine } from 'lib/utils/string-utils.js';
 
 import { updateRoles } from './role-updaters.js';
 import {
   changeRole,
   recalculateThreadPermissions,
   commitMembershipChangeset,
 } from './thread-permission-updaters.js';
 import createMessages from '../creators/message-creator.js';
 import { getRolePermissionBlobs } from '../creators/role-creator.js';
 import { createUpdates } from '../creators/update-creator.js';
 import { dbQuery, SQL } from '../database/database.js';
 import { fetchEntryInfos } from '../fetchers/entry-fetchers.js';
 import { fetchMessageInfos } from '../fetchers/message-fetchers.js';
 import {
   fetchThreadInfos,
   fetchServerThreadInfos,
   determineThreadAncestry,
 } from '../fetchers/thread-fetchers.js';
 import {
   checkThreadPermission,
   viewerIsMember as fetchViewerIsMember,
   checkThread,
   validateCandidateMembers,
 } from '../fetchers/thread-permission-fetchers.js';
 import {
   verifyUserIDs,
   verifyUserOrCookieIDs,
 } from '../fetchers/user-fetchers.js';
 import type { Viewer } from '../session/viewer.js';
 import RelationshipChangeset from '../utils/relationship-changeset.js';
 
 async function updateRole(
   viewer: Viewer,
   request: RoleChangeRequest,
 ): Promise<ChangeThreadSettingsResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [memberIDs, hasPermission] = await Promise.all([
     verifyUserIDs(request.memberIDs),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.CHANGE_ROLE,
     ),
   ]);
   if (memberIDs.length === 0) {
     throw new ServerError('invalid_parameters');
   }
   if (!hasPermission) {
     throw new ServerError('invalid_credentials');
   }
 
   const query = SQL`
     SELECT user, role
     FROM memberships
     WHERE user IN (${memberIDs}) AND thread = ${request.threadID}
   `;
   const [result] = await dbQuery(query);
 
   let nonMemberUser = false;
   let numResults = 0;
   for (const row of result) {
     if (row.role <= 0) {
       nonMemberUser = true;
       break;
     }
     numResults++;
   }
   if (nonMemberUser || numResults < memberIDs.length) {
     throw new ServerError('invalid_parameters');
   }
 
   const changeset = await changeRole(request.threadID, memberIDs, request.role);
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.CHANGE_ROLE,
     threadID: request.threadID,
     creatorID: viewer.userID,
     time: Date.now(),
     userIDs: memberIDs,
     newRole: request.role,
   };
   const newMessageInfos = await createMessages(viewer, [messageData]);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function removeMembers(
   viewer: Viewer,
   request: RemoveMembersRequest,
 ): Promise<ChangeThreadSettingsResult> {
   const viewerID = viewer.userID;
   if (request.memberIDs.includes(viewerID)) {
     throw new ServerError('invalid_parameters');
   }
 
   const [memberIDs, hasPermission] = await Promise.all([
     verifyUserOrCookieIDs(request.memberIDs),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.REMOVE_MEMBERS,
     ),
   ]);
   if (memberIDs.length === 0) {
     throw new ServerError('invalid_parameters');
   }
   if (!hasPermission) {
     throw new ServerError('invalid_credentials');
   }
 
   const query = SQL`
     SELECT m.user, m.role, t.default_role
     FROM memberships m
     LEFT JOIN threads t ON t.id = m.thread
     WHERE m.user IN (${memberIDs}) AND m.thread = ${request.threadID}
   `;
   const [result] = await dbQuery(query);
 
   let nonDefaultRoleUser = false;
   const actualMemberIDs = [];
   for (const row of result) {
     if (row.role <= 0) {
       continue;
     }
     actualMemberIDs.push(row.user.toString());
     if (row.role !== row.default_role) {
       nonDefaultRoleUser = true;
     }
   }
 
   if (nonDefaultRoleUser) {
     const hasChangeRolePermission = await checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.CHANGE_ROLE,
     );
     if (!hasChangeRolePermission) {
       throw new ServerError('invalid_credentials');
     }
   }
 
   const changeset = await changeRole(request.threadID, actualMemberIDs, 0);
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const newMessageInfos = await (async () => {
     if (actualMemberIDs.length === 0) {
       return [];
     }
     const messageData = {
       type: messageTypes.REMOVE_MEMBERS,
       threadID: request.threadID,
       creatorID: viewerID,
       time: Date.now(),
       removedUserIDs: actualMemberIDs,
     };
     return await createMessages(viewer, [messageData]);
   })();
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function leaveThread(
   viewer: Viewer,
   request: LeaveThreadRequest,
 ): Promise<LeaveThreadResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [fetchThreadResult, hasPermission] = await Promise.all([
     fetchThreadInfos(viewer, SQL`t.id = ${request.threadID}`),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.LEAVE_THREAD,
     ),
   ]);
 
   const threadInfo = fetchThreadResult.threadInfos[request.threadID];
 
   if (!viewerIsMember(threadInfo)) {
     if (hasMinCodeVersion(viewer.platformDetails, 62)) {
       return {
         updatesResult: { newUpdates: [] },
       };
     }
     const { threadInfos } = await fetchThreadInfos(viewer);
     return {
       threadInfos,
       updatesResult: {
         newUpdates: [],
       },
     };
   }
 
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   const viewerID = viewer.userID;
   if (threadHasAdminRole(threadInfo)) {
     let otherUsersExist = false;
     let otherAdminsExist = false;
     for (const member of threadInfo.members) {
       const role = member.role;
       if (!role || member.id === viewerID) {
         continue;
       }
       otherUsersExist = true;
       if (roleIsAdminRole(threadInfo.roles[role])) {
         otherAdminsExist = true;
         break;
       }
     }
     if (otherUsersExist && !otherAdminsExist) {
       throw new ServerError('invalid_parameters');
     }
   }
 
   const changeset = await changeRole(request.threadID, [viewerID], 0);
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.LEAVE_THREAD,
     threadID: request.threadID,
     creatorID: viewerID,
     time: Date.now(),
   };
   await createMessages(viewer, [messageData]);
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates } };
   }
 
   return {
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
   };
 }
 
 type UpdateThreadOptions = Shape<{
   +forceAddMembers: boolean,
   +forceUpdateRoot: boolean,
   +silenceMessages: boolean,
   +ignorePermissions: boolean,
 }>;
 
 async function updateThread(
   viewer: Viewer,
   request: UpdateThreadRequest,
   options?: UpdateThreadOptions,
 ): Promise<ChangeThreadSettingsResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
   const forceAddMembers = options?.forceAddMembers ?? false;
   const forceUpdateRoot = options?.forceUpdateRoot ?? false;
   const silenceMessages = options?.silenceMessages ?? false;
   const ignorePermissions =
     (options?.ignorePermissions && viewer.isScriptViewer) ?? false;
   const validationPromises = {};
 
   const changedFields = {};
   const sqlUpdate = {};
   const untrimmedName = request.changes.name;
   if (untrimmedName !== undefined && untrimmedName !== null) {
     const name = firstLine(untrimmedName);
+    if (name.search(validChatNameRegex) === -1) {
+      throw new ServerError('invalid_chat_name');
+    }
     changedFields.name = name;
     sqlUpdate.name = name ?? null;
   }
   const { description } = request.changes;
   if (description !== undefined && description !== null) {
     changedFields.description = description;
     sqlUpdate.description = description ?? null;
   }
   if (request.changes.color) {
     const color = request.changes.color.toLowerCase();
     changedFields.color = color;
     sqlUpdate.color = color;
   }
   const { parentThreadID } = request.changes;
   if (parentThreadID !== undefined) {
     // TODO some sort of message when this changes
     sqlUpdate.parent_thread_id = parentThreadID;
   }
 
   const threadType = request.changes.type;
   if (threadType !== null && threadType !== undefined) {
     changedFields.type = threadType;
     sqlUpdate.type = threadType;
   }
 
   if (
     !ignorePermissions &&
     threadType !== null &&
     threadType !== undefined &&
     threadType !== threadTypes.COMMUNITY_OPEN_SUBTHREAD &&
     threadType !== threadTypes.COMMUNITY_SECRET_SUBTHREAD
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const newMemberIDs =
     request.changes.newMemberIDs && request.changes.newMemberIDs.length > 0
       ? [...new Set(request.changes.newMemberIDs)]
       : null;
 
   if (
     Object.keys(sqlUpdate).length === 0 &&
     !newMemberIDs &&
     !forceUpdateRoot
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   validationPromises.serverThreadInfos = fetchServerThreadInfos(
     SQL`t.id = ${request.threadID}`,
   );
 
   validationPromises.hasNecessaryPermissions = (async () => {
     if (ignorePermissions) {
       return;
     }
     const checks = [];
     if (sqlUpdate.name !== undefined) {
       checks.push({
         check: 'permission',
         permission: threadPermissions.EDIT_THREAD_NAME,
       });
     }
     if (sqlUpdate.description !== undefined) {
       checks.push({
         check: 'permission',
         permission: threadPermissions.EDIT_THREAD_DESCRIPTION,
       });
     }
     if (sqlUpdate.color !== undefined) {
       checks.push({
         check: 'permission',
         permission: threadPermissions.EDIT_THREAD_COLOR,
       });
     }
     if (parentThreadID !== undefined || sqlUpdate.type !== undefined) {
       checks.push({
         check: 'permission',
         permission: threadPermissions.EDIT_PERMISSIONS,
       });
     }
     if (newMemberIDs) {
       checks.push({
         check: 'permission',
         permission: threadPermissions.ADD_MEMBERS,
       });
     }
     const hasNecessaryPermissions = await checkThread(
       viewer,
       request.threadID,
       checks,
     );
     if (!hasNecessaryPermissions) {
       throw new ServerError('invalid_credentials');
     }
   })();
 
   const { serverThreadInfos } = await promiseAll(validationPromises);
 
   const serverThreadInfo = serverThreadInfos.threadInfos[request.threadID];
   if (!serverThreadInfo) {
     throw new ServerError('internal_error');
   }
 
   // Threads with source message should be visible to everyone, but we can't
   // guarantee it for COMMUNITY_SECRET_SUBTHREAD threads so we forbid it for
   // now. In the future, if we want to support this, we would need to unlink the
   // source message.
   if (
     threadType !== null &&
     threadType !== undefined &&
     threadType !== threadTypes.SIDEBAR &&
     threadType !== threadTypes.COMMUNITY_OPEN_SUBTHREAD &&
     serverThreadInfo.sourceMessageID
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   // You can't change the parent thread of a current or former SIDEBAR
   if (parentThreadID !== undefined && serverThreadInfo.sourceMessageID) {
     throw new ServerError('invalid_parameters');
   }
 
   const oldThreadType = serverThreadInfo.type;
   const oldParentThreadID = serverThreadInfo.parentThreadID;
   const oldContainingThreadID = serverThreadInfo.containingThreadID;
   const oldCommunity = serverThreadInfo.community;
   const oldDepth = serverThreadInfo.depth;
 
   const nextThreadType =
     threadType !== null && threadType !== undefined
       ? threadType
       : oldThreadType;
   let nextParentThreadID =
     parentThreadID !== undefined ? parentThreadID : oldParentThreadID;
 
   // Does the new thread type preclude a parent?
   if (
     threadType !== undefined &&
     threadType !== null &&
     getThreadTypeParentRequirement(threadType) === 'disabled' &&
     nextParentThreadID !== null
   ) {
     nextParentThreadID = null;
     sqlUpdate.parent_thread_id = null;
   }
 
   // Does the new thread type require a parent?
   if (
     threadType !== undefined &&
     threadType !== null &&
     getThreadTypeParentRequirement(threadType) === 'required' &&
     nextParentThreadID === null
   ) {
     throw new ServerError('no_parent_thread_specified');
   }
 
   const determineThreadAncestryPromise = determineThreadAncestry(
     nextParentThreadID,
     nextThreadType,
   );
 
   const confirmParentPermissionPromise = (async () => {
     if (ignorePermissions || !nextParentThreadID) {
       return;
     }
     if (
       nextParentThreadID === oldParentThreadID &&
       (nextThreadType === threadTypes.SIDEBAR) ===
         (oldThreadType === threadTypes.SIDEBAR)
     ) {
       return;
     }
     const hasParentPermission = await checkThreadPermission(
       viewer,
       nextParentThreadID,
       nextThreadType === threadTypes.SIDEBAR
         ? threadPermissions.CREATE_SIDEBARS
         : threadPermissions.CREATE_SUBCHANNELS,
     );
     if (!hasParentPermission) {
       throw new ServerError('invalid_parameters');
     }
   })();
 
   const rolesNeedUpdate = forceUpdateRoot || nextThreadType !== oldThreadType;
 
   const validateNewMembersPromise = (async () => {
     if (!newMemberIDs || ignorePermissions) {
       return;
     }
 
     const defaultRolePermissionsPromise = (async () => {
       let rolePermissions;
       if (!rolesNeedUpdate) {
         const rolePermissionsQuery = SQL`
           SELECT r.permissions
           FROM threads t
           LEFT JOIN roles r ON r.id = t.default_role
           WHERE t.id = ${request.threadID}
         `;
         const [result] = await dbQuery(rolePermissionsQuery);
         if (result.length > 0) {
           rolePermissions = JSON.parse(result[0].permissions);
         }
       }
       if (!rolePermissions) {
         rolePermissions = getRolePermissionBlobs(nextThreadType).Members;
       }
       return rolePermissions;
     })();
 
     const [defaultRolePermissions, nextThreadAncestry] = await Promise.all([
       defaultRolePermissionsPromise,
       determineThreadAncestryPromise,
     ]);
 
     const { newMemberIDs: validatedIDs } = await validateCandidateMembers(
       viewer,
       { newMemberIDs },
       {
         threadType: nextThreadType,
         parentThreadID: nextParentThreadID,
         containingThreadID: nextThreadAncestry.containingThreadID,
         defaultRolePermissions,
       },
       { requireRelationship: !forceAddMembers },
     );
     if (
       validatedIDs &&
       Number(validatedIDs?.length) < Number(newMemberIDs?.length)
     ) {
       throw new ServerError('invalid_credentials');
     }
   })();
 
   const { nextThreadAncestry } = await promiseAll({
     nextThreadAncestry: determineThreadAncestryPromise,
     confirmParentPermissionPromise,
     validateNewMembersPromise,
   });
   if (nextThreadAncestry.containingThreadID !== oldContainingThreadID) {
     sqlUpdate.containing_thread_id = nextThreadAncestry.containingThreadID;
   }
   if (nextThreadAncestry.community !== oldCommunity) {
     if (!ignorePermissions) {
       throw new ServerError('invalid_parameters');
     }
     sqlUpdate.community = nextThreadAncestry.community;
   }
   if (nextThreadAncestry.depth !== oldDepth) {
     sqlUpdate.depth = nextThreadAncestry.depth;
   }
 
   const updateQueryPromise = (async () => {
     if (Object.keys(sqlUpdate).length === 0) {
       return;
     }
     const updateQuery = SQL`
       UPDATE threads SET ${sqlUpdate} WHERE id = ${request.threadID}
     `;
     await dbQuery(updateQuery);
   })();
 
   const updateRolesPromise = (async () => {
     if (rolesNeedUpdate) {
       await updateRoles(viewer, request.threadID, nextThreadType);
     }
   })();
 
   const intermediatePromises = {};
   intermediatePromises.updateQuery = updateQueryPromise;
   intermediatePromises.updateRoles = updateRolesPromise;
 
   if (newMemberIDs) {
     intermediatePromises.addMembersChangeset = (async () => {
       await Promise.all([updateQueryPromise, updateRolesPromise]);
       return await changeRole(request.threadID, newMemberIDs, null, {
         setNewMembersToUnread: true,
       });
     })();
   }
 
   const threadRootChanged =
     rolesNeedUpdate || nextParentThreadID !== oldParentThreadID;
   if (threadRootChanged) {
     intermediatePromises.recalculatePermissionsChangeset = (async () => {
       await Promise.all([updateQueryPromise, updateRolesPromise]);
       return await recalculateThreadPermissions(request.threadID);
     })();
   }
 
   const {
     addMembersChangeset,
     recalculatePermissionsChangeset,
   } = await promiseAll(intermediatePromises);
 
   const membershipRows = [];
   const relationshipChangeset = new RelationshipChangeset();
   if (recalculatePermissionsChangeset) {
     const {
       membershipRows: recalculateMembershipRows,
       relationshipChangeset: recalculateRelationshipChangeset,
     } = recalculatePermissionsChangeset;
     membershipRows.push(...recalculateMembershipRows);
     relationshipChangeset.addAll(recalculateRelationshipChangeset);
   }
   let addedMemberIDs;
   if (addMembersChangeset) {
     const {
       membershipRows: addMembersMembershipRows,
       relationshipChangeset: addMembersRelationshipChangeset,
     } = addMembersChangeset;
     addedMemberIDs = addMembersMembershipRows
       .filter(
         row =>
           row.operation === 'save' &&
           row.threadID === request.threadID &&
           Number(row.role) > 0,
       )
       .map(row => row.userID);
     membershipRows.push(...addMembersMembershipRows);
     relationshipChangeset.addAll(addMembersRelationshipChangeset);
   }
 
   const changeset = { membershipRows, relationshipChangeset };
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
     {
       // This forces an update for this thread,
       // regardless of whether any membership rows are changed
       changedThreadIDs:
         Object.keys(sqlUpdate).length > 0
           ? new Set([request.threadID])
           : new Set(),
     },
   );
 
   let newMessageInfos = [];
   if (!silenceMessages) {
     const time = Date.now();
     const messageDatas = [];
     for (const fieldName in changedFields) {
       const newValue = changedFields[fieldName];
       messageDatas.push({
         type: messageTypes.CHANGE_SETTINGS,
         threadID: request.threadID,
         creatorID: viewer.userID,
         time,
         field: fieldName,
         value: newValue,
       });
     }
     if (addedMemberIDs && addedMemberIDs.length > 0) {
       messageDatas.push({
         type: messageTypes.ADD_MEMBERS,
         threadID: request.threadID,
         creatorID: viewer.userID,
         time,
         addedUserIDs: addedMemberIDs,
       });
     }
     newMessageInfos = await createMessages(viewer, messageDatas);
   }
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return { updatesResult: { newUpdates: viewerUpdates }, newMessageInfos };
   }
 
   return {
     threadInfo: threadInfos[request.threadID],
     threadInfos,
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     newMessageInfos,
   };
 }
 
 async function joinThread(
   viewer: Viewer,
   request: ServerThreadJoinRequest,
 ): Promise<ThreadJoinResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const [isMember, hasPermission] = await Promise.all([
     fetchViewerIsMember(viewer, request.threadID),
     checkThreadPermission(
       viewer,
       request.threadID,
       threadPermissions.JOIN_THREAD,
     ),
   ]);
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   // TODO: determine code version
   const hasCodeVersionBelow87 = !hasMinCodeVersion(viewer.platformDetails, 87);
   const hasCodeVersionBelow62 = !hasMinCodeVersion(viewer.platformDetails, 62);
 
   const { calendarQuery } = request;
   if (isMember) {
     const response: ThreadJoinResult = {
       rawMessageInfos: [],
       truncationStatuses: {},
       userInfos: {},
       updatesResult: {
         newUpdates: [],
       },
     };
     if (calendarQuery && hasCodeVersionBelow87) {
       response.rawEntryInfos = [];
     }
     if (hasCodeVersionBelow62) {
       response.threadInfos = {};
     }
     return response;
   }
 
   if (calendarQuery) {
     const threadFilterIDs = filteredThreadIDs(calendarQuery.filters);
     if (
       !threadFilterIDs ||
       threadFilterIDs.size !== 1 ||
       threadFilterIDs.values().next().value !== request.threadID
     ) {
       throw new ServerError('invalid_parameters');
     }
   }
 
   const changeset = await changeRole(request.threadID, [viewer.userID], null);
 
   const membershipResult = await commitMembershipChangeset(viewer, changeset, {
     calendarQuery,
   });
 
   const messageData = {
     type: messageTypes.JOIN_THREAD,
     threadID: request.threadID,
     creatorID: viewer.userID,
     time: Date.now(),
   };
   const newMessages = await createMessages(viewer, [messageData]);
 
   const messageSelectionCriteria = {
     threadCursors: { [request.threadID]: false },
   };
 
   if (!hasCodeVersionBelow87) {
     return {
       rawMessageInfos: newMessages,
       truncationStatuses: {},
       userInfos: membershipResult.userInfos,
       updatesResult: {
         newUpdates: membershipResult.viewerUpdates,
       },
     };
   }
 
   const [fetchMessagesResult, fetchEntriesResult] = await Promise.all([
     fetchMessageInfos(viewer, messageSelectionCriteria, defaultNumberPerThread),
     calendarQuery ? fetchEntryInfos(viewer, [calendarQuery]) : undefined,
   ]);
   const rawEntryInfos = fetchEntriesResult && fetchEntriesResult.rawEntryInfos;
   const response: ThreadJoinResult = {
     rawMessageInfos: fetchMessagesResult.rawMessageInfos,
     truncationStatuses: fetchMessagesResult.truncationStatuses,
     userInfos: membershipResult.userInfos,
     updatesResult: {
       newUpdates: membershipResult.viewerUpdates,
     },
   };
   if (hasCodeVersionBelow62) {
     response.threadInfos = membershipResult.threadInfos;
   }
   if (rawEntryInfos) {
     response.rawEntryInfos = rawEntryInfos;
   }
   return response;
 }
 
 async function updateThreadMembers(viewer: Viewer) {
   const { threadInfos } = await fetchThreadInfos(
     viewer,
     SQL`t.parent_thread_id IS NOT NULL `,
   );
 
   const updateDatas = [];
   const time = Date.now();
   for (const threadID in threadInfos) {
     updateDatas.push({
       type: updateTypes.UPDATE_THREAD,
       userID: viewer.id,
       time,
       threadID: threadID,
       targetSession: viewer.session,
     });
   }
 
   await createUpdates(updateDatas);
 }
 
 export {
   updateRole,
   removeMembers,
   leaveThread,
   updateThread,
   joinThread,
   updateThreadMembers,
 };
diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
index 43dd7daa2..ca779e231 100644
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -1,1533 +1,1541 @@
 // @flow
 
 import invariant from 'invariant';
 import _find from 'lodash/fp/find.js';
 import * as React from 'react';
 import stringHash from 'string-hash';
 import tinycolor from 'tinycolor2';
 
 import { type ParserRules } from './markdown.js';
 import { getMessageTitle } from './message-utils.js';
 import { relationshipBlockedInEitherDirection } from './relationship-utils.js';
 import threadWatcher from './thread-watcher.js';
 import {
   fetchMostRecentMessagesActionTypes,
   fetchMostRecentMessages,
 } from '../actions/message-actions.js';
 import {
   changeThreadMemberRolesActionTypes,
   newThreadActionTypes,
   removeUsersFromThreadActionTypes,
 } from '../actions/thread-actions.js';
 import { searchUsers as searchUserCall } from '../actions/user-actions.js';
 import ashoat from '../facts/ashoat.js';
 import genesis from '../facts/genesis.js';
 import {
   permissionLookup,
   getAllThreadPermissions,
   makePermissionsBlob,
 } from '../permissions/thread-permissions.js';
 import type {
   ChatThreadItem,
   ChatMessageInfoItem,
 } from '../selectors/chat-selectors.js';
 import { useGlobalThreadSearchIndex } from '../selectors/nav-selectors.js';
 import {
   threadInfoSelector,
   pendingToRealizedThreadIDsSelector,
 } from '../selectors/thread-selectors.js';
 import {
   getRelativeMemberInfos,
   usersWithPersonalThreadSelector,
 } from '../selectors/user-selectors.js';
 import type { CalendarQuery } from '../types/entry-types.js';
 import type {
   RobotextMessageInfo,
   ComposableMessageInfo,
 } from '../types/message-types.js';
 import { userRelationshipStatus } from '../types/relationship-types.js';
 import {
   type RawThreadInfo,
   type ThreadInfo,
   type ThreadPermission,
   type MemberInfo,
   type ServerThreadInfo,
   type RelativeMemberInfo,
   type ThreadCurrentUserInfo,
   type RoleInfo,
   type ServerMemberInfo,
   type ThreadPermissionsInfo,
   type ThreadType,
   type ClientNewThreadRequest,
   type NewThreadResult,
   type ChangeThreadSettingsPayload,
   threadTypes,
   threadPermissions,
   threadTypeIsCommunityRoot,
   assertThreadType,
 } from '../types/thread-types.js';
 import { type ClientUpdateInfo, updateTypes } from '../types/update-types.js';
 import type {
   GlobalAccountUserInfo,
   UserInfos,
   UserInfo,
   AccountUserInfo,
 } from '../types/user-types.js';
 import {
   useDispatchActionPromise,
   useServerCall,
 } from '../utils/action-utils.js';
 import type { DispatchActionPromise } from '../utils/action-utils.js';
 import type { GetENSNames } from '../utils/ens-helpers.js';
 import {
   ET,
   entityTextToRawString,
   getEntityTextAsString,
   type ThreadEntity,
 } from '../utils/entity-text.js';
 import { values } from '../utils/objects.js';
 import { useSelector } from '../utils/redux-utils.js';
 import { firstLine } from '../utils/string-utils.js';
 import { trimText } from '../utils/text-utils.js';
 
+const chatNameMaxLength = 191;
+const chatNameMinLength = 0;
+const secondCharRange = `{${chatNameMinLength},${chatNameMaxLength}}`;
+const validChatNameRegexString = `^.${secondCharRange}$`;
+const validChatNameRegex: RegExp = new RegExp(validChatNameRegexString);
+
 function colorIsDark(color: string): boolean {
   return tinycolor(`#${color}`).isDark();
 }
 
 const selectedThreadColorsObj = Object.freeze({
   a: '4b87aa',
   b: '5c9f5f',
   c: 'b8753d',
   d: 'aa4b4b',
   e: '6d49ab',
   f: 'c85000',
   g: '008f83',
   h: '648caa',
   i: '57697f',
   j: '575757',
 });
 
 const selectedThreadColors: $ReadOnlyArray<string> = values(
   selectedThreadColorsObj,
 );
 export type SelectedThreadColors = $Values<typeof selectedThreadColorsObj>;
 
 function generateRandomColor(): string {
   return selectedThreadColors[
     Math.floor(Math.random() * selectedThreadColors.length)
   ];
 }
 
 function generatePendingThreadColor(userIDs: $ReadOnlyArray<string>): string {
   const ids = [...userIDs].sort().join('#');
   const colorIdx = stringHash(ids) % selectedThreadColors.length;
   return selectedThreadColors[colorIdx];
 }
 
 function threadHasPermission(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
   permission: ThreadPermission,
 ): boolean {
   if (!threadInfo) {
     return false;
   }
   invariant(
     !permissionsDisabledByBlock.has(permission) || threadInfo?.uiName,
     `${permission} can be disabled by a block, but threadHasPermission can't ` +
       'check for a block on RawThreadInfo. Please pass in ThreadInfo instead!',
   );
   if (!threadInfo.currentUser.permissions[permission]) {
     return false;
   }
   return threadInfo.currentUser.permissions[permission].value;
 }
 
 function viewerIsMember(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return !!(
     threadInfo &&
     threadInfo.currentUser.role !== null &&
     threadInfo.currentUser.role !== undefined
   );
 }
 
 function threadIsInHome(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return !!(threadInfo && threadInfo.currentUser.subscription.home);
 }
 
 // Can have messages
 function threadInChatList(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return (
     viewerIsMember(threadInfo) &&
     threadHasPermission(threadInfo, threadPermissions.VISIBLE)
   );
 }
 
 function threadIsTopLevel(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return threadInChatList(threadInfo) && threadIsChannel(threadInfo);
 }
 
 function threadIsChannel(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return !!(threadInfo && threadInfo.type !== threadTypes.SIDEBAR);
 }
 
 function threadIsSidebar(threadInfo: ?(ThreadInfo | RawThreadInfo)): boolean {
   return threadInfo?.type === threadTypes.SIDEBAR;
 }
 
 function threadInBackgroundChatList(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
 ): boolean {
   return threadInChatList(threadInfo) && !threadIsInHome(threadInfo);
 }
 
 function threadInHomeChatList(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
 ): boolean {
   return threadInChatList(threadInfo) && threadIsInHome(threadInfo);
 }
 
 // Can have Calendar entries,
 // does appear as a top-level entity in the thread list
 function threadInFilterList(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
 ): boolean {
   return (
     threadInChatList(threadInfo) &&
     !!threadInfo &&
     threadInfo.type !== threadTypes.SIDEBAR
   );
 }
 
 function userIsMember(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
   userID: string,
 ): boolean {
   if (!threadInfo) {
     return false;
   }
   if (threadInfo.id === genesis.id) {
     return true;
   }
   return threadInfo.members.some(member => member.id === userID && member.role);
 }
 
 function threadActualMembers(
   memberInfos: $ReadOnlyArray<MemberInfo | RelativeMemberInfo>,
 ): $ReadOnlyArray<string> {
   return memberInfos
     .filter(memberInfo => memberInfo.role)
     .map(memberInfo => memberInfo.id);
 }
 
 function threadOtherMembers<T: MemberInfo | RelativeMemberInfo>(
   memberInfos: $ReadOnlyArray<T>,
   viewerID: ?string,
 ): $ReadOnlyArray<T> {
   return memberInfos.filter(
     memberInfo => memberInfo.role && memberInfo.id !== viewerID,
   );
 }
 
 function threadMembersWithoutAddedAshoat<T: ThreadInfo | RawThreadInfo>(
   threadInfo: T,
 ): $PropertyType<T, 'members'> {
   if (threadInfo.community !== genesis.id) {
     return threadInfo.members;
   }
   return threadInfo.members.filter(
     member => member.id !== ashoat.id || member.role,
   );
 }
 
 function threadIsGroupChat(threadInfo: ThreadInfo | RawThreadInfo): boolean {
   return (
     threadMembersWithoutAddedAshoat(threadInfo).filter(
       member =>
         member.role || member.permissions[threadPermissions.VOICED]?.value,
     ).length > 2
   );
 }
 
 function threadOrParentThreadIsGroupChat(
   threadInfo: RawThreadInfo | ThreadInfo,
 ) {
   return threadMembersWithoutAddedAshoat(threadInfo).length > 2;
 }
 
 function threadIsPending(threadID: ?string): boolean {
   return !!threadID?.startsWith('pending');
 }
 
 function getSingleOtherUser(
   threadInfo: ThreadInfo | RawThreadInfo,
   viewerID: ?string,
 ): ?string {
   if (!viewerID) {
     return undefined;
   }
   const otherMembers = threadOtherMembers(threadInfo.members, viewerID);
   if (otherMembers.length !== 1) {
     return undefined;
   }
   return otherMembers[0].id;
 }
 
 function getPendingThreadID(
   threadType: ThreadType,
   memberIDs: $ReadOnlyArray<string>,
   sourceMessageID: ?string,
 ): string {
   const pendingThreadKey = sourceMessageID
     ? `sidebar/${sourceMessageID}`
     : [...memberIDs].sort().join('+');
   const pendingThreadTypeString = sourceMessageID ? '' : `type${threadType}/`;
   return `pending/${pendingThreadTypeString}${pendingThreadKey}`;
 }
 
 const pendingThreadIDRegex =
   'pending/(type[0-9]+/[0-9]+(\\+[0-9]+)*|sidebar/[0-9]+)';
 
 type PendingThreadIDContents = {
   +threadType: ThreadType,
   +memberIDs: $ReadOnlyArray<string>,
   +sourceMessageID: ?string,
 };
 
 function parsePendingThreadID(
   pendingThreadID: string,
 ): ?PendingThreadIDContents {
   const pendingRegex = new RegExp(`^${pendingThreadIDRegex}$`);
   const pendingThreadIDMatches = pendingRegex.exec(pendingThreadID);
   if (!pendingThreadIDMatches) {
     return null;
   }
   const [threadTypeString, threadKey] = pendingThreadIDMatches[1].split('/');
   const threadType =
     threadTypeString === 'sidebar'
       ? threadTypes.SIDEBAR
       : assertThreadType(Number(threadTypeString.replace('type', '')));
   const memberIDs = threadTypeString === 'sidebar' ? [] : threadKey.split('+');
   const sourceMessageID = threadTypeString === 'sidebar' ? threadKey : null;
   return {
     threadType,
     memberIDs,
     sourceMessageID,
   };
 }
 
 type CreatePendingThreadArgs = {
   +viewerID: string,
   +threadType: ThreadType,
   +members?: $ReadOnlyArray<GlobalAccountUserInfo | UserInfo>,
   +parentThreadInfo?: ?ThreadInfo,
   +threadColor?: ?string,
   +name?: ?string,
   +sourceMessageID?: string,
 };
 
 function createPendingThread({
   viewerID,
   threadType,
   members,
   parentThreadInfo,
   threadColor,
   name,
   sourceMessageID,
 }: CreatePendingThreadArgs): ThreadInfo {
   const now = Date.now();
   const nonViewerMembers = members
     ? members.filter(member => member.id !== viewerID)
     : [];
   const nonViewerMemberIDs = nonViewerMembers.map(member => member.id);
   const memberIDs = [...nonViewerMemberIDs, viewerID];
   const threadID = getPendingThreadID(threadType, memberIDs, sourceMessageID);
 
   const permissions = {
     [threadPermissions.KNOW_OF]: true,
     [threadPermissions.VISIBLE]: true,
     [threadPermissions.VOICED]: true,
   };
 
   const membershipPermissions = getAllThreadPermissions(
     makePermissionsBlob(permissions, null, threadID, threadType),
     threadID,
   );
   const role = {
     id: `${threadID}/role`,
     name: 'Members',
     permissions,
     isDefault: true,
   };
 
   const rawThreadInfo = {
     id: threadID,
     type: threadType,
     name: name ?? null,
     description: null,
     color: threadColor ?? generatePendingThreadColor(memberIDs),
     creationTime: now,
     parentThreadID: parentThreadInfo?.id ?? null,
     containingThreadID: getContainingThreadID(parentThreadInfo, threadType),
     community: getCommunity(parentThreadInfo),
     members: [
       {
         id: viewerID,
         role: role.id,
         permissions: membershipPermissions,
         isSender: false,
       },
       ...nonViewerMembers.map(member => ({
         id: member.id,
         role: role.id,
         permissions: membershipPermissions,
         isSender: false,
       })),
     ],
     roles: {
       [role.id]: role,
     },
     currentUser: {
       role: role.id,
       permissions: membershipPermissions,
       subscription: {
         pushNotifs: false,
         home: false,
       },
       unread: false,
     },
     repliesCount: 0,
     sourceMessageID,
   };
 
   const userInfos = {};
   nonViewerMembers.forEach(member => (userInfos[member.id] = member));
 
   return threadInfoFromRawThreadInfo(rawThreadInfo, viewerID, userInfos);
 }
 
 function createPendingThreadItem(
   viewerID: string,
   user: GlobalAccountUserInfo,
 ): ChatThreadItem {
   const threadInfo = createPendingThread({
     viewerID,
     threadType: threadTypes.PERSONAL,
     members: [user],
   });
 
   return {
     type: 'chatThreadItem',
     threadInfo,
     mostRecentMessageInfo: null,
     mostRecentNonLocalMessage: null,
     lastUpdatedTime: threadInfo.creationTime,
     lastUpdatedTimeIncludingSidebars: threadInfo.creationTime,
     sidebars: [],
     pendingPersonalThreadUserInfo: {
       id: user.id,
       username: user.username,
     },
   };
 }
 
 type SharedCreatePendingSidebarInput = {
   +sourceMessageInfo: ComposableMessageInfo | RobotextMessageInfo,
   +parentThreadInfo: ThreadInfo,
   +viewerID: string,
 };
 
 type BaseCreatePendingSidebarInput = {
   ...SharedCreatePendingSidebarInput,
   +messageTitle: string,
 };
 function baseCreatePendingSidebar(
   input: BaseCreatePendingSidebarInput,
 ): ThreadInfo {
   const { sourceMessageInfo, parentThreadInfo, viewerID, messageTitle } = input;
   const { color, type: parentThreadType } = parentThreadInfo;
   const threadName = trimText(messageTitle, 30);
 
   const initialMembers = new Map();
   if (userIsMember(parentThreadInfo, sourceMessageInfo.creator.id)) {
     const {
       id: sourceAuthorID,
       username: sourceAuthorUsername,
     } = sourceMessageInfo.creator;
     invariant(
       sourceAuthorUsername,
       'sourceAuthorUsername should be set in createPendingSidebar',
     );
     const initialMemberUserInfo: GlobalAccountUserInfo = {
       id: sourceAuthorID,
       username: sourceAuthorUsername,
     };
     initialMembers.set(sourceAuthorID, initialMemberUserInfo);
   }
   const singleOtherUser = getSingleOtherUser(parentThreadInfo, viewerID);
   if (parentThreadType === threadTypes.PERSONAL && singleOtherUser) {
     const singleOtherUsername = parentThreadInfo.members.find(
       member => member.id === singleOtherUser,
     )?.username;
     invariant(
       singleOtherUsername,
       'singleOtherUsername should be set in createPendingSidebar',
     );
     const singleOtherUserInfo: GlobalAccountUserInfo = {
       id: singleOtherUser,
       username: singleOtherUsername,
     };
     initialMembers.set(singleOtherUser, singleOtherUserInfo);
   }
 
   return createPendingThread({
     viewerID,
     threadType: threadTypes.SIDEBAR,
     members: [...initialMembers.values()],
     parentThreadInfo,
     threadColor: color,
     name: threadName,
     sourceMessageID: sourceMessageInfo.id,
   });
 }
 
 // The message title here may have ETH addresses that aren't resolved to ENS
 // names. This function should only be used in cases where we're sure that we
 // don't care about the thread title. We should prefer createPendingSidebar
 // wherever possible
 type CreateUnresolvedPendingSidebarInput = {
   ...SharedCreatePendingSidebarInput,
   +markdownRules: ParserRules,
 };
 function createUnresolvedPendingSidebar(
   input: CreateUnresolvedPendingSidebarInput,
 ): ThreadInfo {
   const {
     sourceMessageInfo,
     parentThreadInfo,
     viewerID,
     markdownRules,
   } = input;
 
   const messageTitleEntityText = getMessageTitle(
     sourceMessageInfo,
     parentThreadInfo,
     markdownRules,
   );
   const messageTitle = entityTextToRawString(messageTitleEntityText, {
     ignoreViewer: true,
   });
 
   return baseCreatePendingSidebar({
     sourceMessageInfo,
     parentThreadInfo,
     messageTitle,
     viewerID,
   });
 }
 
 type CreatePendingSidebarInput = {
   ...SharedCreatePendingSidebarInput,
   +markdownRules: ParserRules,
   +getENSNames: ?GetENSNames,
 };
 async function createPendingSidebar(
   input: CreatePendingSidebarInput,
 ): Promise<ThreadInfo> {
   const {
     sourceMessageInfo,
     parentThreadInfo,
     viewerID,
     markdownRules,
     getENSNames,
   } = input;
 
   const messageTitleEntityText = getMessageTitle(
     sourceMessageInfo,
     parentThreadInfo,
     markdownRules,
   );
   const messageTitle = await getEntityTextAsString(
     messageTitleEntityText,
     getENSNames,
     { ignoreViewer: true },
   );
   invariant(
     messageTitle !== null && messageTitle !== undefined,
     'getEntityTextAsString only returns falsey when passed falsey',
   );
 
   return baseCreatePendingSidebar({
     sourceMessageInfo,
     parentThreadInfo,
     messageTitle,
     viewerID,
   });
 }
 
 function pendingThreadType(numberOfOtherMembers: number): 4 | 6 | 7 {
   if (numberOfOtherMembers === 0) {
     return threadTypes.PRIVATE;
   } else if (numberOfOtherMembers === 1) {
     return threadTypes.PERSONAL;
   } else {
     return threadTypes.LOCAL;
   }
 }
 
 function threadTypeCanBePending(threadType: ThreadType): boolean {
   return (
     threadType === threadTypes.PERSONAL ||
     threadType === threadTypes.LOCAL ||
     threadType === threadTypes.SIDEBAR ||
     threadType === threadTypes.PRIVATE
   );
 }
 
 type CreateRealThreadParameters = {
   +threadInfo: ThreadInfo,
   +dispatchActionPromise: DispatchActionPromise,
   +createNewThread: ClientNewThreadRequest => Promise<NewThreadResult>,
   +sourceMessageID: ?string,
   +viewerID: ?string,
   +handleError?: () => mixed,
   +calendarQuery: CalendarQuery,
 };
 async function createRealThreadFromPendingThread({
   threadInfo,
   dispatchActionPromise,
   createNewThread,
   sourceMessageID,
   viewerID,
   calendarQuery,
 }: CreateRealThreadParameters): Promise<string> {
   if (!threadIsPending(threadInfo.id)) {
     return threadInfo.id;
   }
 
   const otherMemberIDs = threadOtherMembers(threadInfo.members, viewerID).map(
     member => member.id,
   );
   let resultPromise;
   if (threadInfo.type !== threadTypes.SIDEBAR) {
     invariant(
       otherMemberIDs.length > 0,
       'otherMemberIDs should not be empty for threads',
     );
     resultPromise = createNewThread({
       type: pendingThreadType(otherMemberIDs.length),
       initialMemberIDs: otherMemberIDs,
       color: threadInfo.color,
       calendarQuery,
     });
   } else {
     invariant(
       sourceMessageID,
       'sourceMessageID should be set when creating a sidebar',
     );
     resultPromise = createNewThread({
       type: threadTypes.SIDEBAR,
       initialMemberIDs: otherMemberIDs,
       color: threadInfo.color,
       sourceMessageID,
       parentThreadID: threadInfo.parentThreadID,
       name: threadInfo.name,
       calendarQuery,
     });
   }
   dispatchActionPromise(newThreadActionTypes, resultPromise);
   const { newThreadID } = await resultPromise;
   return newThreadID;
 }
 
 type RawThreadInfoOptions = {
   +includeVisibilityRules?: ?boolean,
   +filterMemberList?: ?boolean,
   +hideThreadStructure?: ?boolean,
   +shimThreadTypes?: ?{
     +[inType: ThreadType]: ThreadType,
   },
   +filterDetailedThreadEditPermissions?: boolean,
 };
 function rawThreadInfoFromServerThreadInfo(
   serverThreadInfo: ServerThreadInfo,
   viewerID: string,
   options?: RawThreadInfoOptions,
 ): ?RawThreadInfo {
   const includeVisibilityRules = options?.includeVisibilityRules;
   const filterMemberList = options?.filterMemberList;
   const hideThreadStructure = options?.hideThreadStructure;
   const shimThreadTypes = options?.shimThreadTypes;
   const filterDetailedThreadEditPermissions =
     options?.filterDetailedThreadEditPermissions;
 
   const members = [];
   let currentUser;
   for (const serverMember of serverThreadInfo.members) {
     if (
       filterMemberList &&
       serverMember.id !== viewerID &&
       !serverMember.role &&
       !memberHasAdminPowers(serverMember)
     ) {
       continue;
     }
     if (
       serverThreadInfo.id === genesis.id &&
       serverMember.id !== viewerID &&
       serverMember.id !== ashoat.id
     ) {
       continue;
     }
     const memberPermissions = filterThreadEditDetailedPermissions(
       serverMember.permissions,
       filterDetailedThreadEditPermissions,
     );
     members.push({
       id: serverMember.id,
       role: serverMember.role,
       permissions: memberPermissions,
       isSender: serverMember.isSender,
     });
     if (serverMember.id === viewerID) {
       currentUser = {
         role: serverMember.role,
         permissions: memberPermissions,
         subscription: serverMember.subscription,
         unread: serverMember.unread,
       };
     }
   }
 
   let currentUserPermissions;
   if (currentUser) {
     currentUserPermissions = currentUser.permissions;
   } else {
     currentUserPermissions = filterThreadEditDetailedPermissions(
       getAllThreadPermissions(null, serverThreadInfo.id),
       filterDetailedThreadEditPermissions,
     );
     currentUser = {
       role: null,
       permissions: currentUserPermissions,
       subscription: {
         home: false,
         pushNotifs: false,
       },
       unread: null,
     };
   }
   if (!permissionLookup(currentUserPermissions, threadPermissions.KNOW_OF)) {
     return null;
   }
 
   let { type } = serverThreadInfo;
   if (
     shimThreadTypes &&
     shimThreadTypes[type] !== null &&
     shimThreadTypes[type] !== undefined
   ) {
     type = shimThreadTypes[type];
   }
 
   let rawThreadInfo: any = {
     id: serverThreadInfo.id,
     type,
     name: serverThreadInfo.name,
     description: serverThreadInfo.description,
     color: serverThreadInfo.color,
     creationTime: serverThreadInfo.creationTime,
     parentThreadID: serverThreadInfo.parentThreadID,
     members,
     roles: serverThreadInfo.roles,
     currentUser,
     repliesCount: serverThreadInfo.repliesCount,
   };
   if (!hideThreadStructure) {
     rawThreadInfo = {
       ...rawThreadInfo,
       containingThreadID: serverThreadInfo.containingThreadID,
       community: serverThreadInfo.community,
     };
   }
   const sourceMessageID = serverThreadInfo.sourceMessageID;
   if (sourceMessageID) {
     rawThreadInfo = { ...rawThreadInfo, sourceMessageID };
   }
   if (includeVisibilityRules) {
     return {
       ...rawThreadInfo,
       visibilityRules: rawThreadInfo.type,
     };
   }
   return rawThreadInfo;
 }
 
 function filterThreadEditDetailedPermissions(
   permissions: ThreadPermissionsInfo,
   shouldFilter: ?boolean,
 ): ThreadPermissionsInfo {
   if (!shouldFilter) {
     return permissions;
   }
   const {
     edit_thread_color,
     edit_thread_description,
     ...newPermissions
   } = permissions;
   return newPermissions;
 }
 
 function threadUIName(threadInfo: ThreadInfo): string | ThreadEntity {
   if (threadInfo.name) {
     return firstLine(threadInfo.name);
   }
   const threadMembers = threadInfo.members.filter(
     memberInfo => memberInfo.role,
   );
   const memberEntities = threadMembers.map(member =>
     ET.user({ userInfo: member }),
   );
   return {
     type: 'thread',
     id: threadInfo.id,
     name: threadInfo.name,
     display: 'uiName',
     uiName: memberEntities,
   };
 }
 
 function threadInfoFromRawThreadInfo(
   rawThreadInfo: RawThreadInfo,
   viewerID: ?string,
   userInfos: UserInfos,
 ): ThreadInfo {
   let threadInfo: ThreadInfo = {
     id: rawThreadInfo.id,
     type: rawThreadInfo.type,
     name: rawThreadInfo.name,
     uiName: '',
     description: rawThreadInfo.description,
     color: rawThreadInfo.color,
     creationTime: rawThreadInfo.creationTime,
     parentThreadID: rawThreadInfo.parentThreadID,
     containingThreadID: rawThreadInfo.containingThreadID,
     community: rawThreadInfo.community,
     members: getRelativeMemberInfos(rawThreadInfo, viewerID, userInfos),
     roles: rawThreadInfo.roles,
     currentUser: getCurrentUser(rawThreadInfo, viewerID, userInfos),
     repliesCount: rawThreadInfo.repliesCount,
   };
   threadInfo = {
     ...threadInfo,
     uiName: threadUIName(threadInfo),
   };
   const { sourceMessageID } = rawThreadInfo;
   if (sourceMessageID) {
     threadInfo = { ...threadInfo, sourceMessageID };
   }
   return threadInfo;
 }
 
 function getCurrentUser(
   threadInfo: RawThreadInfo | ThreadInfo,
   viewerID: ?string,
   userInfos: UserInfos,
 ): ThreadCurrentUserInfo {
   if (!threadFrozenDueToBlock(threadInfo, viewerID, userInfos)) {
     return threadInfo.currentUser;
   }
 
   return {
     ...threadInfo.currentUser,
     permissions: {
       ...threadInfo.currentUser.permissions,
       ...disabledPermissions,
     },
   };
 }
 
 function threadIsWithBlockedUserOnly(
   threadInfo: RawThreadInfo | ThreadInfo,
   viewerID: ?string,
   userInfos: UserInfos,
   checkOnlyViewerBlock?: boolean,
 ): boolean {
   if (
     threadOrParentThreadIsGroupChat(threadInfo) ||
     threadOrParentThreadHasAdminRole(threadInfo)
   ) {
     return false;
   }
 
   const otherUserID = getSingleOtherUser(threadInfo, viewerID);
   if (!otherUserID) {
     return false;
   }
   const otherUserRelationshipStatus =
     userInfos[otherUserID]?.relationshipStatus;
 
   if (checkOnlyViewerBlock) {
     return (
       otherUserRelationshipStatus === userRelationshipStatus.BLOCKED_BY_VIEWER
     );
   }
 
   return (
     !!otherUserRelationshipStatus &&
     relationshipBlockedInEitherDirection(otherUserRelationshipStatus)
   );
 }
 
 function threadFrozenDueToBlock(
   threadInfo: RawThreadInfo | ThreadInfo,
   viewerID: ?string,
   userInfos: UserInfos,
 ): boolean {
   return threadIsWithBlockedUserOnly(threadInfo, viewerID, userInfos);
 }
 
 function threadFrozenDueToViewerBlock(
   threadInfo: RawThreadInfo | ThreadInfo,
   viewerID: ?string,
   userInfos: UserInfos,
 ): boolean {
   return threadIsWithBlockedUserOnly(threadInfo, viewerID, userInfos, true);
 }
 
 function rawThreadInfoFromThreadInfo(threadInfo: ThreadInfo): RawThreadInfo {
   let rawThreadInfo: RawThreadInfo = {
     id: threadInfo.id,
     type: threadInfo.type,
     name: threadInfo.name,
     description: threadInfo.description,
     color: threadInfo.color,
     creationTime: threadInfo.creationTime,
     parentThreadID: threadInfo.parentThreadID,
     containingThreadID: threadInfo.containingThreadID,
     community: threadInfo.community,
     members: threadInfo.members.map(relativeMemberInfo => ({
       id: relativeMemberInfo.id,
       role: relativeMemberInfo.role,
       permissions: relativeMemberInfo.permissions,
       isSender: relativeMemberInfo.isSender,
     })),
     roles: threadInfo.roles,
     currentUser: threadInfo.currentUser,
     repliesCount: threadInfo.repliesCount,
   };
   const { sourceMessageID } = threadInfo;
   if (sourceMessageID) {
     rawThreadInfo = { ...rawThreadInfo, sourceMessageID };
   }
   return rawThreadInfo;
 }
 
 const threadTypeDescriptions: { [ThreadType]: string } = {
   [threadTypes.COMMUNITY_OPEN_SUBTHREAD]:
     'Anybody in the parent channel can see an open subchannel.',
   [threadTypes.COMMUNITY_SECRET_SUBTHREAD]:
     'Only visible to its members and admins of ancestor channels.',
 };
 
 function usersInThreadInfo(threadInfo: RawThreadInfo | ThreadInfo): string[] {
   const userIDs = new Set();
   for (const member of threadInfo.members) {
     userIDs.add(member.id);
   }
   return [...userIDs];
 }
 
 function memberIsAdmin(
   memberInfo: RelativeMemberInfo | MemberInfo,
   threadInfo: ThreadInfo | RawThreadInfo,
 ): boolean {
   return !!(
     memberInfo.role && roleIsAdminRole(threadInfo.roles[memberInfo.role])
   );
 }
 
 // Since we don't have access to all of the ancestor ThreadInfos, we approximate
 // "parent admin" as anybody with CHANGE_ROLE permissions.
 function memberHasAdminPowers(
   memberInfo: RelativeMemberInfo | MemberInfo | ServerMemberInfo,
 ): boolean {
   return !!memberInfo.permissions[threadPermissions.CHANGE_ROLE]?.value;
 }
 
 function roleIsAdminRole(roleInfo: ?RoleInfo): boolean {
   return !!(roleInfo && !roleInfo.isDefault && roleInfo.name === 'Admins');
 }
 
 function threadHasAdminRole(
   threadInfo: ?(RawThreadInfo | ThreadInfo | ServerThreadInfo),
 ): boolean {
   if (!threadInfo) {
     return false;
   }
   return !!_find({ name: 'Admins' })(threadInfo.roles);
 }
 
 function threadOrParentThreadHasAdminRole(
   threadInfo: RawThreadInfo | ThreadInfo,
 ) {
   return (
     threadMembersWithoutAddedAshoat(threadInfo).filter(member =>
       memberHasAdminPowers(member),
     ).length > 0
   );
 }
 
 function identifyInvalidatedThreads(
   updateInfos: $ReadOnlyArray<ClientUpdateInfo>,
 ): Set<string> {
   const invalidated = new Set();
   for (const updateInfo of updateInfos) {
     if (updateInfo.type === updateTypes.DELETE_THREAD) {
       invalidated.add(updateInfo.threadID);
     }
   }
   return invalidated;
 }
 
 const permissionsDisabledByBlockArray = [
   threadPermissions.VOICED,
   threadPermissions.EDIT_ENTRIES,
   threadPermissions.EDIT_THREAD_NAME,
   threadPermissions.EDIT_THREAD_COLOR,
   threadPermissions.EDIT_THREAD_DESCRIPTION,
   threadPermissions.CREATE_SUBCHANNELS,
   threadPermissions.CREATE_SIDEBARS,
   threadPermissions.JOIN_THREAD,
   threadPermissions.EDIT_PERMISSIONS,
   threadPermissions.ADD_MEMBERS,
   threadPermissions.REMOVE_MEMBERS,
 ];
 
 const permissionsDisabledByBlock: Set<ThreadPermission> = new Set(
   permissionsDisabledByBlockArray,
 );
 
 const disabledPermissions: ThreadPermissionsInfo = permissionsDisabledByBlockArray.reduce(
   (permissions: ThreadPermissionsInfo, permission: string) => ({
     ...permissions,
     [permission]: { value: false, source: null },
   }),
   {},
 );
 
 // Consider updating itemHeight in native/chat/chat-thread-list.react.js
 // if you change this
 const emptyItemText: string =
   `Background chats are just like normal chats, except they don't ` +
   `contribute to your unread count.\n\n` +
   `To move a chat over here, switch the “Background” option in its settings.`;
 
 function threadNoun(threadType: ThreadType): string {
   if (threadType === threadTypes.SIDEBAR) {
     return 'thread';
   } else if (
     threadType === threadTypes.COMMUNITY_ROOT ||
     threadType === threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT ||
     threadType === threadTypes.COMMUNITY_OPEN_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_SECRET_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD ||
     threadType === threadTypes.GENESIS
   ) {
     return 'channel';
   } else {
     return 'chat';
   }
 }
 
 function threadLabel(threadType: ThreadType): string {
   if (
     threadType === threadTypes.COMMUNITY_OPEN_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD
   ) {
     return 'Open';
   } else if (threadType === threadTypes.PERSONAL) {
     return 'Personal';
   } else if (threadType === threadTypes.SIDEBAR) {
     return 'Thread';
   } else if (threadType === threadTypes.PRIVATE) {
     return 'Private';
   } else if (
     threadType === threadTypes.COMMUNITY_ROOT ||
     threadType === threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT ||
     threadType === threadTypes.GENESIS
   ) {
     return 'Community';
   } else {
     return 'Secret';
   }
 }
 
 function useWatchThread(threadInfo: ?ThreadInfo) {
   const dispatchActionPromise = useDispatchActionPromise();
   const callFetchMostRecentMessages = useServerCall(fetchMostRecentMessages);
 
   const threadID = threadInfo?.id;
   const threadNotInChatList = !threadInChatList(threadInfo);
   React.useEffect(() => {
     if (threadID && threadNotInChatList) {
       threadWatcher.watchID(threadID);
       dispatchActionPromise(
         fetchMostRecentMessagesActionTypes,
         callFetchMostRecentMessages(threadID),
       );
     }
     return () => {
       if (threadID && threadNotInChatList) {
         threadWatcher.removeID(threadID);
       }
     };
   }, [
     callFetchMostRecentMessages,
     dispatchActionPromise,
     threadNotInChatList,
     threadID,
   ]);
 }
 
 type ExistingThreadInfoFinderParams = {
   +searching: boolean,
   +userInfoInputArray: $ReadOnlyArray<AccountUserInfo>,
 };
 type ExistingThreadInfoFinder = (
   params: ExistingThreadInfoFinderParams,
 ) => ?ThreadInfo;
 function useExistingThreadInfoFinder(
   baseThreadInfo: ?ThreadInfo,
 ): ExistingThreadInfoFinder {
   const threadInfos = useSelector(threadInfoSelector);
   const viewerID = useSelector(
     state => state.currentUserInfo && state.currentUserInfo.id,
   );
   const userInfos = useSelector(state => state.userStore.userInfos);
 
   const pendingToRealizedThreadIDs = useSelector(state =>
     pendingToRealizedThreadIDsSelector(state.threadStore.threadInfos),
   );
   return React.useCallback(
     (params: ExistingThreadInfoFinderParams): ?ThreadInfo => {
       if (!baseThreadInfo) {
         return null;
       }
 
       const realizedThreadInfo = threadInfos[baseThreadInfo.id];
       if (realizedThreadInfo) {
         return realizedThreadInfo;
       }
 
       if (!viewerID || !threadIsPending(baseThreadInfo.id)) {
         return baseThreadInfo;
       }
 
       invariant(
         threadTypeCanBePending(baseThreadInfo.type),
         `ThreadInfo has pending ID ${baseThreadInfo.id}, but type that ` +
           `should not be pending ${baseThreadInfo.type}`,
       );
 
       const { searching, userInfoInputArray } = params;
 
       const { sourceMessageID } = baseThreadInfo;
       const pendingThreadID = searching
         ? getPendingThreadID(
             pendingThreadType(userInfoInputArray.length),
             [...userInfoInputArray.map(user => user.id), viewerID],
             sourceMessageID,
           )
         : getPendingThreadID(
             baseThreadInfo.type,
             baseThreadInfo.members.map(member => member.id),
             sourceMessageID,
           );
 
       const realizedThreadID = pendingToRealizedThreadIDs.get(pendingThreadID);
       if (realizedThreadID && threadInfos[realizedThreadID]) {
         return threadInfos[realizedThreadID];
       }
 
       const updatedThread = searching
         ? createPendingThread({
             viewerID,
             threadType: pendingThreadType(userInfoInputArray.length),
             members: userInfoInputArray,
           })
         : baseThreadInfo;
       return {
         ...updatedThread,
         currentUser: getCurrentUser(updatedThread, viewerID, userInfos),
       };
     },
     [
       baseThreadInfo,
       threadInfos,
       viewerID,
       pendingToRealizedThreadIDs,
       userInfos,
     ],
   );
 }
 
 type ThreadTypeParentRequirement = 'optional' | 'required' | 'disabled';
 function getThreadTypeParentRequirement(
   threadType: ThreadType,
 ): ThreadTypeParentRequirement {
   if (
     threadType === threadTypes.COMMUNITY_OPEN_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD ||
     //threadType === threadTypes.COMMUNITY_SECRET_SUBTHREAD ||
     threadType === threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD ||
     threadType === threadTypes.SIDEBAR
   ) {
     return 'required';
   } else if (
     threadType === threadTypes.COMMUNITY_ROOT ||
     threadType === threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT ||
     threadType === threadTypes.GENESIS ||
     threadType === threadTypes.PERSONAL ||
     threadType === threadTypes.PRIVATE
   ) {
     return 'disabled';
   } else {
     return 'optional';
   }
 }
 
 function threadMemberHasPermission(
   threadInfo: ServerThreadInfo | RawThreadInfo | ThreadInfo,
   memberID: string,
   permission: ThreadPermission,
 ): boolean {
   for (const member of threadInfo.members) {
     if (member.id !== memberID) {
       continue;
     }
     return permissionLookup(member.permissions, permission);
   }
   return false;
 }
 
 function useCanCreateSidebarFromMessage(
   threadInfo: ThreadInfo,
   messageInfo: ComposableMessageInfo | RobotextMessageInfo,
 ): boolean {
   const messageCreatorUserInfo = useSelector(
     state => state.userStore.userInfos[messageInfo.creator.id],
   );
 
   if (!messageInfo.id || threadInfo.sourceMessageID === messageInfo.id) {
     return false;
   }
 
   const messageCreatorRelationship = messageCreatorUserInfo?.relationshipStatus;
   const creatorRelationshipHasBlock =
     messageCreatorRelationship &&
     relationshipBlockedInEitherDirection(messageCreatorRelationship);
 
   const hasPermission = threadHasPermission(
     threadInfo,
     threadPermissions.CREATE_SIDEBARS,
   );
 
   return hasPermission && !creatorRelationshipHasBlock;
 }
 
 function useSidebarExistsOrCanBeCreated(
   threadInfo: ThreadInfo,
   messageItem: ChatMessageInfoItem,
 ): boolean {
   const canCreateSidebarFromMessage = useCanCreateSidebarFromMessage(
     threadInfo,
     messageItem.messageInfo,
   );
   return !!messageItem.threadCreatedFromMessage || canCreateSidebarFromMessage;
 }
 
 function checkIfDefaultMembersAreVoiced(threadInfo: ThreadInfo): boolean {
   const defaultRoleID = Object.keys(threadInfo.roles).find(
     roleID => threadInfo.roles[roleID].isDefault,
   );
   invariant(
     defaultRoleID !== undefined,
     'all threads should have a default role',
   );
   const defaultRole = threadInfo.roles[defaultRoleID];
   return !!defaultRole.permissions[threadPermissions.VOICED];
 }
 
 function draftKeyFromThreadID(threadID: string): string {
   return `${threadID}/message_composer`;
 }
 
 function getContainingThreadID(
   parentThreadInfo: ?ServerThreadInfo | RawThreadInfo | ThreadInfo,
   threadType: ThreadType,
 ): ?string {
   if (!parentThreadInfo) {
     return null;
   }
   if (threadType === threadTypes.SIDEBAR) {
     return parentThreadInfo.id;
   }
   if (!parentThreadInfo.containingThreadID) {
     return parentThreadInfo.id;
   }
   return parentThreadInfo.containingThreadID;
 }
 
 function getCommunity(
   parentThreadInfo: ?ServerThreadInfo | RawThreadInfo | ThreadInfo,
 ): ?string {
   if (!parentThreadInfo) {
     return null;
   }
   const { id, community, type } = parentThreadInfo;
   if (community !== null && community !== undefined) {
     return community;
   }
   if (threadTypeIsCommunityRoot(type)) {
     return id;
   }
   return null;
 }
 
 function getThreadListSearchResults(
   chatListData: $ReadOnlyArray<ChatThreadItem>,
   searchText: string,
   threadFilter: ThreadInfo => boolean,
   threadSearchResults: $ReadOnlySet<string>,
   usersSearchResults: $ReadOnlyArray<GlobalAccountUserInfo>,
   viewerID: ?string,
 ): $ReadOnlyArray<ChatThreadItem> {
   if (!searchText) {
     return chatListData.filter(
       item =>
         threadIsTopLevel(item.threadInfo) && threadFilter(item.threadInfo),
     );
   }
 
   const privateThreads = [];
   const personalThreads = [];
   const otherThreads = [];
   for (const item of chatListData) {
     if (!threadSearchResults.has(item.threadInfo.id)) {
       continue;
     }
     if (item.threadInfo.type === threadTypes.PRIVATE) {
       privateThreads.push({ ...item, sidebars: [] });
     } else if (item.threadInfo.type === threadTypes.PERSONAL) {
       personalThreads.push({ ...item, sidebars: [] });
     } else {
       otherThreads.push({ ...item, sidebars: [] });
     }
   }
 
   const chatItems = [...privateThreads, ...personalThreads, ...otherThreads];
   if (viewerID) {
     chatItems.push(
       ...usersSearchResults.map(user =>
         createPendingThreadItem(viewerID, user),
       ),
     );
   }
   return chatItems;
 }
 
 type ThreadListSearchResult = {
   +threadSearchResults: $ReadOnlySet<string>,
   +usersSearchResults: $ReadOnlyArray<GlobalAccountUserInfo>,
 };
 function useThreadListSearch(
   chatListData: $ReadOnlyArray<ChatThreadItem>,
   searchText: string,
   viewerID: ?string,
 ): ThreadListSearchResult {
   const callSearchUsers = useServerCall(searchUserCall);
   const usersWithPersonalThread = useSelector(usersWithPersonalThreadSelector);
   const searchUsers = React.useCallback(
     async (usernamePrefix: string) => {
       if (usernamePrefix.length === 0) {
         return [];
       }
 
       const { userInfos } = await callSearchUsers(usernamePrefix);
       return userInfos.filter(
         info => !usersWithPersonalThread.has(info.id) && info.id !== viewerID,
       );
     },
     [callSearchUsers, usersWithPersonalThread, viewerID],
   );
 
   const [threadSearchResults, setThreadSearchResults] = React.useState(
     new Set(),
   );
   const [usersSearchResults, setUsersSearchResults] = React.useState([]);
   const threadSearchIndex = useGlobalThreadSearchIndex();
   React.useEffect(() => {
     (async () => {
       const results = threadSearchIndex.getSearchResults(searchText);
       setThreadSearchResults(new Set(results));
       const usersResults = await searchUsers(searchText);
       setUsersSearchResults(usersResults);
     })();
   }, [searchText, chatListData, threadSearchIndex, searchUsers]);
 
   return { threadSearchResults, usersSearchResults };
 }
 
 function removeMemberFromThread(
   threadInfo: ThreadInfo,
   memberInfo: RelativeMemberInfo,
   dispatchActionPromise: DispatchActionPromise,
   removeUserFromThreadServerCall: (
     threadID: string,
     memberIDs: $ReadOnlyArray<string>,
   ) => Promise<ChangeThreadSettingsPayload>,
 ) {
   const customKeyName = `${removeUsersFromThreadActionTypes.started}:${memberInfo.id}`;
   dispatchActionPromise(
     removeUsersFromThreadActionTypes,
     removeUserFromThreadServerCall(threadInfo.id, [memberInfo.id]),
     { customKeyName },
   );
 }
 
 function switchMemberAdminRoleInThread(
   threadInfo: ThreadInfo,
   memberInfo: RelativeMemberInfo,
   isCurrentlyAdmin: boolean,
   dispatchActionPromise: DispatchActionPromise,
   changeUserRoleServerCall: (
     threadID: string,
     memberIDs: $ReadOnlyArray<string>,
     newRole: string,
   ) => Promise<ChangeThreadSettingsPayload>,
 ) {
   let newRole = null;
   for (const roleID in threadInfo.roles) {
     const role = threadInfo.roles[roleID];
     if (isCurrentlyAdmin && role.isDefault) {
       newRole = role.id;
       break;
     } else if (!isCurrentlyAdmin && roleIsAdminRole(role)) {
       newRole = role.id;
       break;
     }
   }
   invariant(newRole !== null, 'Could not find new role');
 
   const customKeyName = `${changeThreadMemberRolesActionTypes.started}:${memberInfo.id}`;
   dispatchActionPromise(
     changeThreadMemberRolesActionTypes,
     changeUserRoleServerCall(threadInfo.id, [memberInfo.id], newRole),
     { customKeyName },
   );
 }
 
 function getAvailableThreadMemberActions(
   memberInfo: RelativeMemberInfo,
   threadInfo: ThreadInfo,
   canEdit: ?boolean = true,
 ): $ReadOnlyArray<'remove_user' | 'remove_admin' | 'make_admin'> {
   const role = memberInfo.role;
   if (!canEdit || !role) {
     return [];
   }
 
   const canRemoveMembers = threadHasPermission(
     threadInfo,
     threadPermissions.REMOVE_MEMBERS,
   );
   const canChangeRoles = threadHasPermission(
     threadInfo,
     threadPermissions.CHANGE_ROLE,
   );
 
   const result = [];
   if (
     canRemoveMembers &&
     !memberInfo.isViewer &&
     (canChangeRoles || threadInfo.roles[role]?.isDefault)
   ) {
     result.push('remove_user');
   }
 
   if (canChangeRoles && memberInfo.username && threadHasAdminRole(threadInfo)) {
     result.push(
       memberIsAdmin(memberInfo, threadInfo) ? 'remove_admin' : 'make_admin',
     );
   }
 
   return result;
 }
 
 export {
   colorIsDark,
   generateRandomColor,
   generatePendingThreadColor,
   threadHasPermission,
   viewerIsMember,
   threadInChatList,
   threadIsTopLevel,
   threadIsChannel,
   threadIsSidebar,
   threadInBackgroundChatList,
   threadInHomeChatList,
   threadIsInHome,
   threadInFilterList,
   userIsMember,
   threadActualMembers,
   threadOtherMembers,
   threadIsGroupChat,
   threadIsPending,
   getSingleOtherUser,
   getPendingThreadID,
   pendingThreadIDRegex,
   parsePendingThreadID,
   createPendingThread,
   createUnresolvedPendingSidebar,
   createPendingSidebar,
   pendingThreadType,
   createRealThreadFromPendingThread,
   getCurrentUser,
   threadFrozenDueToBlock,
   threadFrozenDueToViewerBlock,
   rawThreadInfoFromServerThreadInfo,
   filterThreadEditDetailedPermissions,
   threadUIName,
   threadInfoFromRawThreadInfo,
   rawThreadInfoFromThreadInfo,
   threadTypeDescriptions,
   usersInThreadInfo,
   memberIsAdmin,
   memberHasAdminPowers,
   roleIsAdminRole,
   threadHasAdminRole,
   identifyInvalidatedThreads,
   permissionsDisabledByBlock,
   emptyItemText,
   threadNoun,
   threadLabel,
   useWatchThread,
   useExistingThreadInfoFinder,
   getThreadTypeParentRequirement,
   threadMemberHasPermission,
   useCanCreateSidebarFromMessage,
   useSidebarExistsOrCanBeCreated,
   checkIfDefaultMembersAreVoiced,
   draftKeyFromThreadID,
   threadTypeCanBePending,
   getContainingThreadID,
   getCommunity,
   getThreadListSearchResults,
   useThreadListSearch,
   removeMemberFromThread,
   switchMemberAdminRoleInThread,
   getAvailableThreadMemberActions,
   selectedThreadColors,
   threadMembersWithoutAddedAshoat,
+  validChatNameRegex,
+  chatNameMaxLength,
 };
diff --git a/native/chat/settings/thread-settings-name.react.js b/native/chat/settings/thread-settings-name.react.js
index 8e0ca4223..e8d7dc466 100644
--- a/native/chat/settings/thread-settings-name.react.js
+++ b/native/chat/settings/thread-settings-name.react.js
@@ -1,232 +1,234 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 import {
   Text,
   Alert,
   ActivityIndicator,
   TextInput as BaseTextInput,
   View,
 } from 'react-native';
 
 import {
   changeThreadSettingsActionTypes,
   changeThreadSettings,
 } from 'lib/actions/thread-actions.js';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors.js';
+import { chatNameMaxLength } from 'lib/shared/thread-utils.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
 import {
   type ResolvedThreadInfo,
   type ChangeThreadSettingsPayload,
   type UpdateThreadRequest,
 } from 'lib/types/thread-types.js';
 import {
   type DispatchActionPromise,
   useServerCall,
   useDispatchActionPromise,
 } from 'lib/utils/action-utils.js';
 import { firstLine } from 'lib/utils/string-utils.js';
 
 import SaveSettingButton from './save-setting-button.react.js';
 import EditSettingButton from '../../components/edit-setting-button.react.js';
 import { SingleLine } from '../../components/single-line.react.js';
 import TextInput from '../../components/text-input.react.js';
 import { useSelector } from '../../redux/redux-utils.js';
 import { type Colors, useStyles, useColors } from '../../themes/colors.js';
 
 type BaseProps = {
   +threadInfo: ResolvedThreadInfo,
   +nameEditValue: ?string,
   +setNameEditValue: (value: ?string, callback?: () => void) => void,
   +canChangeSettings: boolean,
 };
 type Props = {
   ...BaseProps,
   // Redux state
   +loadingStatus: LoadingStatus,
   +colors: Colors,
   +styles: typeof unboundStyles,
   // Redux dispatch functions
   +dispatchActionPromise: DispatchActionPromise,
   // async functions that hit server APIs
   +changeThreadSettings: (
     update: UpdateThreadRequest,
   ) => Promise<ChangeThreadSettingsPayload>,
 };
 class ThreadSettingsName extends React.PureComponent<Props> {
   textInput: ?React.ElementRef<typeof BaseTextInput>;
 
   render() {
     return (
       <View style={this.props.styles.row}>
         <Text style={this.props.styles.label}>Name</Text>
         {this.renderContent()}
       </View>
     );
   }
 
   renderContent() {
     if (
       this.props.nameEditValue === null ||
       this.props.nameEditValue === undefined
     ) {
       return (
         <React.Fragment>
           <SingleLine style={this.props.styles.currentValue}>
             {this.props.threadInfo.uiName}
           </SingleLine>
           <EditSettingButton
             onPress={this.onPressEdit}
             canChangeSettings={this.props.canChangeSettings}
           />
         </React.Fragment>
       );
     }
 
     let button;
     if (this.props.loadingStatus !== 'loading') {
       button = <SaveSettingButton onPress={this.onSubmit} />;
     } else {
       button = (
         <ActivityIndicator
           size="small"
           color={this.props.colors.panelForegroundSecondaryLabel}
         />
       );
     }
 
     return (
       <React.Fragment>
         <TextInput
           style={this.props.styles.currentValue}
           value={this.props.nameEditValue}
           onChangeText={this.props.setNameEditValue}
           autoFocus={true}
           selectTextOnFocus={true}
           onBlur={this.onSubmit}
           editable={this.props.loadingStatus !== 'loading'}
           ref={this.textInputRef}
           selectionColor={`#${this.props.threadInfo.color}`}
+          maxLength={chatNameMaxLength}
         />
         {button}
       </React.Fragment>
     );
   }
 
   textInputRef = (textInput: ?React.ElementRef<typeof BaseTextInput>) => {
     this.textInput = textInput;
   };
 
   threadEditName() {
     return firstLine(
       this.props.threadInfo.name ? this.props.threadInfo.name : '',
     );
   }
 
   onPressEdit = () => {
     this.props.setNameEditValue(this.threadEditName());
   };
 
   onSubmit = () => {
     invariant(
       this.props.nameEditValue !== null &&
         this.props.nameEditValue !== undefined,
       'should be set',
     );
     const name = firstLine(this.props.nameEditValue);
 
     if (name === this.threadEditName()) {
       this.props.setNameEditValue(null);
       return;
     }
 
     const editNamePromise = this.editName(name);
     this.props.dispatchActionPromise(
       changeThreadSettingsActionTypes,
       editNamePromise,
       { customKeyName: `${changeThreadSettingsActionTypes.started}:name` },
     );
     editNamePromise.then(() => {
       this.props.setNameEditValue(null);
     });
   };
 
   async editName(newName: string) {
     try {
       return await this.props.changeThreadSettings({
         threadID: this.props.threadInfo.id,
         changes: { name: newName },
       });
     } catch (e) {
       Alert.alert(
         'Unknown error',
         'Uhh... try again?',
         [{ text: 'OK', onPress: this.onErrorAcknowledged }],
         { cancelable: false },
       );
       throw e;
     }
   }
 
   onErrorAcknowledged = () => {
     this.props.setNameEditValue(this.threadEditName(), () => {
       invariant(this.textInput, 'textInput should be set');
       this.textInput.focus();
     });
   };
 }
 
 const unboundStyles = {
   currentValue: {
     color: 'panelForegroundSecondaryLabel',
     flex: 1,
     fontFamily: 'Arial',
     fontSize: 16,
     margin: 0,
     paddingLeft: 4,
     paddingRight: 0,
     paddingVertical: 0,
     borderBottomColor: 'transparent',
   },
   label: {
     color: 'panelForegroundTertiaryLabel',
     fontSize: 16,
     width: 96,
   },
   row: {
     backgroundColor: 'panelForeground',
     flexDirection: 'row',
     paddingHorizontal: 24,
     paddingVertical: 8,
   },
 };
 
 const loadingStatusSelector = createLoadingStatusSelector(
   changeThreadSettingsActionTypes,
   `${changeThreadSettingsActionTypes.started}:name`,
 );
 
 const ConnectedThreadSettingsName: React.ComponentType<BaseProps> = React.memo<BaseProps>(
   function ConnectedThreadSettingsName(props: BaseProps) {
     const styles = useStyles(unboundStyles);
     const colors = useColors();
     const loadingStatus = useSelector(loadingStatusSelector);
 
     const dispatchActionPromise = useDispatchActionPromise();
     const callChangeThreadSettings = useServerCall(changeThreadSettings);
 
     return (
       <ThreadSettingsName
         {...props}
         styles={styles}
         colors={colors}
         loadingStatus={loadingStatus}
         dispatchActionPromise={dispatchActionPromise}
         changeThreadSettings={callChangeThreadSettings}
       />
     );
   },
 );
 
 export default ConnectedThreadSettingsName;
diff --git a/web/modals/input.react.js b/web/modals/input.react.js
index c9d6fd314..f4f68d93a 100644
--- a/web/modals/input.react.js
+++ b/web/modals/input.react.js
@@ -1,63 +1,64 @@
 // @flow
 
 import classNames from 'classnames';
 import * as React from 'react';
 
 import css from './input.css';
 
 export type BaseInputProps = {
   +value: string,
   +onChange: (value: SyntheticEvent<HTMLInputElement>) => mixed,
   +onBlur?: (value: SyntheticEvent<HTMLInputElement>) => mixed,
   +disabled?: boolean,
   +label?: string,
   +id?: string,
   +className?: string,
 };
 
 export type InputProps = {
   ...BaseInputProps,
   +type: string,
   +placeholder: string,
+  +maxLength?: number,
 };
 
 function Input(props: InputProps, ref): React.Node {
   const {
     label: labelProp,
     disabled = false,
     className = '',
     id,
     ...rest
   } = props;
 
   let label;
   if (labelProp) {
     label = (
       <label className={css.label} htmlFor={id}>
         {labelProp}
       </label>
     );
   }
 
   const inputClassName = classNames(css.input, className);
 
   return (
     <>
       {label}
       <input
         className={inputClassName}
         id={id}
         disabled={disabled}
         {...rest}
         ref={ref}
       />
     </>
   );
 }
 
 const ForwardedInput: React.AbstractComponent<
   InputProps,
   HTMLInputElement,
 > = React.forwardRef<InputProps, HTMLInputElement>(Input);
 
 export default ForwardedInput;
diff --git a/web/modals/threads/settings/thread-settings-general-tab.react.js b/web/modals/threads/settings/thread-settings-general-tab.react.js
index d60787a57..94ff024cf 100644
--- a/web/modals/threads/settings/thread-settings-general-tab.react.js
+++ b/web/modals/threads/settings/thread-settings-general-tab.react.js
@@ -1,199 +1,203 @@
 // @flow
 
 import * as React from 'react';
 import tinycolor from 'tinycolor2';
 
 import {
   changeThreadSettingsActionTypes,
   changeThreadSettings,
 } from 'lib/actions/thread-actions.js';
-import { threadHasPermission } from 'lib/shared/thread-utils.js';
+import {
+  threadHasPermission,
+  chatNameMaxLength,
+} from 'lib/shared/thread-utils.js';
 import { type SetState } from 'lib/types/hook-types.js';
 import {
   type ThreadInfo,
   type ThreadChanges,
   threadPermissions,
 } from 'lib/types/thread-types.js';
 import {
   useDispatchActionPromise,
   useServerCall,
 } from 'lib/utils/action-utils.js';
 import { firstLine } from 'lib/utils/string-utils.js';
 
 import SubmitSection from './submit-section.react.js';
 import css from './thread-settings-general-tab.css';
 import LoadingIndicator from '../../../loading-indicator.react.js';
 import Input from '../../input.react.js';
 import ColorSelector from '../color-selector.react.js';
 
 type ThreadSettingsGeneralTabProps = {
   +threadSettingsOperationInProgress: boolean,
   +threadInfo: ThreadInfo,
   +threadNamePlaceholder: string,
   +queuedChanges: ThreadChanges,
   +setQueuedChanges: SetState<ThreadChanges>,
   +setErrorMessage: SetState<?string>,
   +errorMessage?: ?string,
 };
 function ThreadSettingsGeneralTab(
   props: ThreadSettingsGeneralTabProps,
 ): React.Node {
   const {
     threadSettingsOperationInProgress,
     threadInfo,
     threadNamePlaceholder,
     queuedChanges,
     setQueuedChanges,
     setErrorMessage,
     errorMessage,
   } = props;
 
   const dispatchActionPromise = useDispatchActionPromise();
   const callChangeThreadSettings = useServerCall(changeThreadSettings);
 
   const nameInputRef = React.useRef();
 
   React.useEffect(() => {
     nameInputRef.current?.focus();
   }, [threadSettingsOperationInProgress]);
 
   const changeQueued: boolean = React.useMemo(
     () => Object.values(queuedChanges).some(v => v !== null && v !== undefined),
     [queuedChanges],
   );
 
   const onChangeName = React.useCallback(
     (event: SyntheticEvent<HTMLInputElement>) => {
       const target = event.currentTarget;
       const newName = firstLine(target.value);
       setQueuedChanges(prevQueuedChanges =>
         Object.freeze({
           ...prevQueuedChanges,
           name: newName !== threadInfo.name ? newName : undefined,
         }),
       );
     },
     [setQueuedChanges, threadInfo.name],
   );
 
   const onChangeDescription = React.useCallback(
     (event: SyntheticEvent<HTMLTextAreaElement>) => {
       const target = event.currentTarget;
       setQueuedChanges(prevQueuedChanges =>
         Object.freeze({
           ...prevQueuedChanges,
           description:
             target.value !== threadInfo.description ? target.value : undefined,
         }),
       );
     },
     [setQueuedChanges, threadInfo.description],
   );
 
   const onChangeColor = React.useCallback(
     (color: string) => {
       setQueuedChanges(prevQueuedChanges =>
         Object.freeze({
           ...prevQueuedChanges,
           color: !tinycolor.equals(color, threadInfo.color) ? color : undefined,
         }),
       );
     },
     [setQueuedChanges, threadInfo.color],
   );
 
   const changeThreadSettingsAction = React.useCallback(async () => {
     try {
       setErrorMessage('');
       return await callChangeThreadSettings({
         threadID: threadInfo.id,
         changes: queuedChanges,
       });
     } catch (e) {
       setErrorMessage('unknown_error');
       throw e;
     } finally {
       setQueuedChanges(Object.freeze({}));
     }
   }, [
     callChangeThreadSettings,
     queuedChanges,
     setErrorMessage,
     setQueuedChanges,
     threadInfo.id,
   ]);
 
   const onSubmit = React.useCallback(
     (event: SyntheticEvent<HTMLElement>) => {
       event.preventDefault();
       dispatchActionPromise(
         changeThreadSettingsActionTypes,
         changeThreadSettingsAction(),
       );
     },
     [changeThreadSettingsAction, dispatchActionPromise],
   );
 
   const threadNameInputDisabled = !threadHasPermission(
     threadInfo,
     threadPermissions.EDIT_THREAD_NAME,
   );
 
   const saveButtonContent = React.useMemo(() => {
     if (threadSettingsOperationInProgress) {
       return <LoadingIndicator status="loading" />;
     }
     return 'Save';
   }, [threadSettingsOperationInProgress]);
 
   return (
     <form method="POST" className={css.container}>
       <div>
         <div className={css.form_title}>Chat name</div>
         <div className={css.form_content}>
           <Input
             type="text"
+            maxLength={chatNameMaxLength}
             value={firstLine(queuedChanges.name ?? threadInfo.name)}
             placeholder={threadNamePlaceholder}
             onChange={onChangeName}
             disabled={
               threadSettingsOperationInProgress || threadNameInputDisabled
             }
             ref={nameInputRef}
           />
         </div>
       </div>
       <div>
         <div className={css.form_title}>Description</div>
         <div className={css.form_content}>
           <textarea
             value={queuedChanges.description ?? threadInfo.description ?? ''}
             placeholder="Chat description"
             onChange={onChangeDescription}
             disabled={threadSettingsOperationInProgress}
             rows={3}
           />
         </div>
       </div>
       <div>
         <div className={css.form_title}>Color</div>
         <div className={css.colorSelectorContainer}>
           <ColorSelector
             currentColor={queuedChanges.color ?? threadInfo.color}
             onColorSelection={onChangeColor}
           />
         </div>
       </div>
       <SubmitSection
         variant="filled"
         errorMessage={errorMessage}
         onClick={onSubmit}
         disabled={threadSettingsOperationInProgress || !changeQueued}
       >
         {saveButtonContent}
       </SubmitSection>
     </form>
   );
 }
 
 export default ThreadSettingsGeneralTab;