diff --git a/server/src/creators/thread-creator.js b/server/src/creators/thread-creator.js
index 781980c4c..53cae8b31 100644
--- a/server/src/creators/thread-creator.js
+++ b/server/src/creators/thread-creator.js
@@ -1,480 +1,488 @@
 // @flow
 
 import invariant from 'invariant';
 
 import bots from 'lib/facts/bots';
 import { relationshipBlockedInEitherDirection } from 'lib/shared/relationship-utils';
 import {
   generatePendingThreadColor,
   generateRandomColor,
   getThreadTypeParentRequirement,
 } from 'lib/shared/thread-utils';
 import { hasMinCodeVersion } from 'lib/shared/version-utils';
 import type { Shape } from 'lib/types/core';
 import { messageTypes } from 'lib/types/message-types';
 import { userRelationshipStatus } from 'lib/types/relationship-types';
 import {
   type NewThreadRequest,
   type NewThreadResponse,
   threadTypes,
   threadPermissions,
 } from 'lib/types/thread-types';
 import { ServerError } from 'lib/utils/errors';
 import { promiseAll } from 'lib/utils/promises';
 import { firstLine } from 'lib/utils/string-utils';
 
 import { dbQuery, SQL } from '../database/database';
 import { fetchMessageInfoByID } from '../fetchers/message-fetchers';
 import { fetchThreadInfos } from '../fetchers/thread-fetchers';
 import { checkThreadPermission } from '../fetchers/thread-permission-fetchers';
 import { fetchKnownUserInfos } from '../fetchers/user-fetchers';
 import type { Viewer } from '../session/viewer';
 import {
   changeRole,
   recalculateThreadPermissions,
   commitMembershipChangeset,
-  setJoinsToUnread,
 } from '../updaters/thread-permission-updaters';
 import RelationshipChangeset from '../utils/relationship-changeset';
 import createIDs from './id-creator';
 import createMessages from './message-creator';
 import { createInitialRolesForNewThread } from './role-creator';
 import type { UpdatesForCurrentSession } from './update-creator';
 
 const { squadbot } = bots;
 
 const privateThreadDescription =
   'This is your private thread, ' +
   'where you can set reminders and jot notes in private!';
 
 type CreateThreadOptions = Shape<{|
   +forceAddMembers: boolean,
   +updatesForCurrentSession: UpdatesForCurrentSession,
   +silentlyFailMembers: boolean,
 |}>;
 
 // If forceAddMembers is set, we will allow the viewer to add random users who
 // they aren't friends with. We will only fail if the viewer is trying to add
 // somebody who they have blocked or has blocked them. On the other hand, if
 // forceAddMembers is not set, we will fail if the viewer tries to add somebody
 // who they aren't friends with and doesn't have a membership row with a
 // nonnegative role for the parent thread.
 async function createThread(
   viewer: Viewer,
   request: NewThreadRequest,
   options?: CreateThreadOptions,
 ): Promise<NewThreadResponse> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const forceAddMembers = options?.forceAddMembers ?? false;
   const updatesForCurrentSession =
     options?.updatesForCurrentSession ?? 'return';
   const silentlyFailMembers = options?.silentlyFailMembers ?? false;
 
   const threadType = request.type;
   const shouldCreateRelationships =
     forceAddMembers || threadType === threadTypes.PERSONAL;
   const parentThreadID = request.parentThreadID ? request.parentThreadID : null;
   const initialMemberIDsFromRequest =
     request.initialMemberIDs && request.initialMemberIDs.length > 0
       ? request.initialMemberIDs
       : null;
   const ghostMemberIDs =
     request.ghostMemberIDs && request.ghostMemberIDs.length > 0
       ? request.ghostMemberIDs
       : null;
 
   const sourceMessageID = request.sourceMessageID
     ? request.sourceMessageID
     : null;
   invariant(
     threadType !== threadTypes.SIDEBAR || sourceMessageID,
     'sourceMessageID should be set for sidebar',
   );
 
   const parentRequirement = getThreadTypeParentRequirement(threadType);
   if (
     (parentRequirement === 'required' && !parentThreadID) ||
     (parentRequirement === 'disabled' && parentThreadID)
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   if (
     threadType === threadTypes.PERSONAL &&
     request.initialMemberIDs?.length !== 1
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const checkPromises = {};
   if (parentThreadID) {
     checkPromises.parentThreadFetch = fetchThreadInfos(
       viewer,
       SQL`t.id = ${parentThreadID}`,
     );
     checkPromises.hasParentPermission = checkThreadPermission(
       viewer,
       parentThreadID,
       threadType === threadTypes.SIDEBAR
         ? threadPermissions.CREATE_SIDEBARS
         : threadPermissions.CREATE_SUBTHREADS,
     );
   }
 
   const memberIDs = [];
   if (initialMemberIDsFromRequest) {
     memberIDs.push(...initialMemberIDsFromRequest);
   }
   if (ghostMemberIDs) {
     memberIDs.push(...ghostMemberIDs);
   }
 
   if (initialMemberIDsFromRequest || ghostMemberIDs) {
     checkPromises.fetchMemberIDs = fetchKnownUserInfos(viewer, memberIDs);
   }
 
   if (sourceMessageID) {
     checkPromises.sourceMessage = fetchMessageInfoByID(viewer, sourceMessageID);
   }
 
   const {
     parentThreadFetch,
     hasParentPermission,
     fetchMemberIDs,
     sourceMessage,
   } = await promiseAll(checkPromises);
 
   let parentThreadMembers;
   if (parentThreadID) {
     invariant(parentThreadFetch, 'parentThreadFetch should be set');
     const parentThreadInfo = parentThreadFetch.threadInfos[parentThreadID];
     if (!hasParentPermission) {
       throw new ServerError('invalid_credentials');
     }
     parentThreadMembers = parentThreadInfo.members.map(
       (userInfo) => userInfo.id,
     );
   }
 
   const relationshipChangeset = new RelationshipChangeset();
   const silencedMemberIDs = new Set();
   if (fetchMemberIDs) {
     invariant(initialMemberIDsFromRequest || ghostMemberIDs, 'should be set');
     for (const memberID of memberIDs) {
       const member = fetchMemberIDs[memberID];
       if (
         !member &&
         shouldCreateRelationships &&
         (threadType !== threadTypes.SIDEBAR ||
           parentThreadMembers?.includes(memberID))
       ) {
         continue;
       } else if (!member && silentlyFailMembers) {
         silencedMemberIDs.add(memberID);
         continue;
       } else if (!member) {
         throw new ServerError('invalid_credentials');
       }
       relationshipChangeset.setRelationshipExists(viewer.id, memberID);
 
       const { relationshipStatus } = member;
       const memberRelationshipHasBlock = !!(
         relationshipStatus &&
         relationshipBlockedInEitherDirection(relationshipStatus)
       );
       if (
         relationshipStatus === userRelationshipStatus.FRIEND &&
         threadType !== threadTypes.SIDEBAR
       ) {
         continue;
       } else if (memberRelationshipHasBlock && silentlyFailMembers) {
         silencedMemberIDs.add(memberID);
       } else if (memberRelationshipHasBlock) {
         throw new ServerError('invalid_credentials');
       } else if (
         parentThreadMembers &&
         parentThreadMembers.includes(memberID)
       ) {
         continue;
       } else if (!shouldCreateRelationships && silentlyFailMembers) {
         silencedMemberIDs.add(memberID);
       } else if (!shouldCreateRelationships) {
         throw new ServerError('invalid_credentials');
       }
     }
   }
 
   const filteredInitialMemberIDs: ?$ReadOnlyArray<string> = initialMemberIDsFromRequest?.filter(
     (id) => !silencedMemberIDs.has(id),
   );
   const initialMemberIDs =
     filteredInitialMemberIDs && filteredInitialMemberIDs.length > 0
       ? filteredInitialMemberIDs
       : null;
 
   const [id] = await createIDs('threads', 1);
   const newRoles = await createInitialRolesForNewThread(id, threadType);
 
   const name = request.name ? firstLine(request.name) : null;
   const description = request.description ? request.description : null;
   let color = request.color
     ? request.color.toLowerCase()
     : generateRandomColor();
   if (threadType === threadTypes.PERSONAL) {
     color = generatePendingThreadColor(
       request.initialMemberIDs ?? [],
       viewer.id,
     );
   }
 
   const time = Date.now();
 
   const row = [
     id,
     threadType,
     name,
     description,
     viewer.userID,
     time,
     color,
     parentThreadID,
     newRoles.default.id,
     sourceMessageID,
   ];
 
   let existingThreadQuery = null;
   if (threadType === threadTypes.PERSONAL) {
     const otherMemberID = initialMemberIDs?.[0];
     invariant(
       otherMemberID,
       'Other member id should be set for a PERSONAL thread',
     );
     existingThreadQuery = SQL`
       SELECT t.id 
       FROM threads t
       INNER JOIN memberships m1 
         ON m1.thread = t.id AND m1.user = ${viewer.userID}
       INNER JOIN memberships m2
         ON m2.thread = t.id AND m2.user = ${otherMemberID}
       WHERE t.type = ${threadTypes.PERSONAL}
         AND m1.role != -1
         AND m2.role != -1
     `;
   } else if (sourceMessageID) {
     existingThreadQuery = SQL`
       SELECT t.id
       FROM threads t
       WHERE t.source_message = ${sourceMessageID}
     `;
   }
 
   if (existingThreadQuery) {
     const query = SQL`
       INSERT INTO threads(id, type, name, description, creator,
         creation_time, color, parent_thread_id, default_role, source_message)
       SELECT ${row}
       WHERE NOT EXISTS (`;
     query.append(existingThreadQuery).append(SQL`)`);
     const [result] = await dbQuery(query);
 
     if (result.affectedRows === 0) {
       const deleteRoles = SQL`
         DELETE FROM roles
         WHERE id IN (${newRoles.default.id}, ${newRoles.creator.id})
       `;
       const deleteIDs = SQL`
         DELETE FROM ids
         WHERE id IN (${id}, ${newRoles.default.id}, ${newRoles.creator.id})
       `;
       const [[existingThreadResult]] = await Promise.all([
         dbQuery(existingThreadQuery),
         dbQuery(deleteRoles),
         dbQuery(deleteIDs),
       ]);
       invariant(existingThreadResult.length > 0, 'thread should exist');
       const existingThreadID = existingThreadResult[0].id.toString();
 
       return {
         newThreadID: existingThreadID,
         updatesResult: {
           newUpdates: [],
         },
         userInfos: {},
         newMessageInfos: [],
       };
     }
   } else {
     const query = SQL`
       INSERT INTO threads(id, type, name, description, creator,
         creation_time, color, parent_thread_id, default_role, source_message)
       VALUES ${[row]}
     `;
     await dbQuery(query);
   }
 
+  let initialMemberPromise;
+  if (initialMemberIDs) {
+    initialMemberPromise = changeRole(id, initialMemberIDs, null, {
+      setNewMembersToUnread: true,
+    });
+  }
+  let ghostMemberPromise;
+  if (ghostMemberIDs) {
+    ghostMemberPromise = changeRole(id, ghostMemberIDs, -1);
+  }
+
   const [
     creatorChangeset,
     initialMembersChangeset,
     ghostMembersChangeset,
     recalculatePermissionsChangeset,
   ] = await Promise.all([
     changeRole(id, [viewer.userID], newRoles.creator.id),
-    initialMemberIDs ? changeRole(id, initialMemberIDs, null) : undefined,
-    ghostMemberIDs ? changeRole(id, ghostMemberIDs, -1) : undefined,
+    initialMemberPromise,
+    ghostMemberPromise,
     recalculateThreadPermissions(id, threadType),
   ]);
 
   if (!creatorChangeset) {
     throw new ServerError('unknown_error');
   }
   const {
     membershipRows: creatorMembershipRows,
     relationshipChangeset: creatorRelationshipChangeset,
   } = creatorChangeset;
 
   const {
     membershipRows: recalculateMembershipRows,
     relationshipChangeset: recalculateRelationshipChangeset,
   } = recalculatePermissionsChangeset;
 
   const membershipRows = [
     ...creatorMembershipRows,
     ...recalculateMembershipRows,
   ];
   relationshipChangeset.addAll(creatorRelationshipChangeset);
   relationshipChangeset.addAll(recalculateRelationshipChangeset);
 
   if (initialMembersChangeset) {
     const {
       membershipRows: initialMembersMembershipRows,
       relationshipChangeset: initialMembersRelationshipChangeset,
     } = initialMembersChangeset;
     membershipRows.push(...initialMembersMembershipRows);
     relationshipChangeset.addAll(initialMembersRelationshipChangeset);
   }
   if (ghostMembersChangeset) {
     const {
       membershipRows: ghostMembersMembershipRows,
       relationshipChangeset: ghostMembersRelationshipChangeset,
     } = ghostMembersChangeset;
     membershipRows.push(...ghostMembersMembershipRows);
     relationshipChangeset.addAll(ghostMembersRelationshipChangeset);
   }
 
-  setJoinsToUnread(membershipRows, viewer.userID, id);
-
   const changeset = { membershipRows, relationshipChangeset };
   const {
     threadInfos,
     viewerUpdates,
     userInfos,
   } = await commitMembershipChangeset(viewer, changeset, {
     updatesForCurrentSession,
   });
 
   const initialMemberAndCreatorIDs = initialMemberIDs
     ? [...initialMemberIDs, viewer.userID]
     : [viewer.userID];
   const messageDatas = [];
   if (threadType !== threadTypes.SIDEBAR) {
     messageDatas.push({
       type: messageTypes.CREATE_THREAD,
       threadID: id,
       creatorID: viewer.userID,
       time,
       initialThreadState: {
         type: threadType,
         name,
         parentThreadID,
         color,
         memberIDs: initialMemberAndCreatorIDs,
       },
     });
   } else {
     invariant(parentThreadID, 'parentThreadID should be set for sidebar');
     if (!sourceMessage || sourceMessage.type === messageTypes.SIDEBAR_SOURCE) {
       throw new ServerError('invalid_parameters');
     }
 
     messageDatas.push(
       {
         type: messageTypes.SIDEBAR_SOURCE,
         threadID: id,
         creatorID: viewer.userID,
         time,
         sourceMessage,
       },
       {
         type: messageTypes.CREATE_SIDEBAR,
         threadID: id,
         creatorID: viewer.userID,
         time,
         sourceMessageAuthorID: sourceMessage.creatorID,
         initialThreadState: {
           name,
           parentThreadID,
           color,
           memberIDs: initialMemberAndCreatorIDs,
         },
       },
     );
   }
 
   if (parentThreadID && threadType !== threadTypes.SIDEBAR) {
     messageDatas.push({
       type: messageTypes.CREATE_SUB_THREAD,
       threadID: parentThreadID,
       creatorID: viewer.userID,
       time,
       childThreadID: id,
     });
   }
   const newMessageInfos = await createMessages(
     viewer,
     messageDatas,
     updatesForCurrentSession,
   );
 
   if (hasMinCodeVersion(viewer.platformDetails, 62)) {
     return {
       newThreadID: id,
       updatesResult: {
         newUpdates: viewerUpdates,
       },
       userInfos,
       newMessageInfos,
     };
   }
 
   return {
     newThreadInfo: threadInfos[id],
     updatesResult: {
       newUpdates: viewerUpdates,
     },
     userInfos,
     newMessageInfos,
   };
 }
 
 function createPrivateThread(
   viewer: Viewer,
   username: string,
 ): Promise<NewThreadResponse> {
   return createThread(
     viewer,
     {
       type: threadTypes.PRIVATE,
       name: username,
       description: privateThreadDescription,
       ghostMemberIDs: [squadbot.userID],
     },
     {
       forceAddMembers: true,
     },
   );
 }
 
 export { createThread, createPrivateThread, privateThreadDescription };
diff --git a/server/src/updaters/thread-permission-updaters.js b/server/src/updaters/thread-permission-updaters.js
index f3e4061bb..a100e1619 100644
--- a/server/src/updaters/thread-permission-updaters.js
+++ b/server/src/updaters/thread-permission-updaters.js
@@ -1,794 +1,781 @@
 // @flow
 
 import invariant from 'invariant';
 import _isEqual from 'lodash/fp/isEqual';
 
 import bots from 'lib/facts/bots';
 import {
   makePermissionsBlob,
   makePermissionsForChildrenBlob,
 } from 'lib/permissions/thread-permissions';
 import type { CalendarQuery } from 'lib/types/entry-types';
 import {
   type ThreadPermissionsBlob,
   type ThreadRolePermissionsBlob,
   type ThreadType,
   assertThreadType,
 } from 'lib/types/thread-types';
 import { updateTypes, type UpdateInfo } from 'lib/types/update-types';
 import type { AccountUserInfo } from 'lib/types/user-types';
 import { ServerError } from 'lib/utils/errors';
 
 import {
   createUpdates,
   type UpdatesForCurrentSession,
 } from '../creators/update-creator';
 import { dbQuery, SQL } from '../database/database';
 import {
   fetchServerThreadInfos,
   rawThreadInfosFromServerThreadInfos,
   type FetchThreadInfosResult,
 } from '../fetchers/thread-fetchers';
 import { rescindPushNotifs } from '../push/rescind';
 import { createScriptViewer } from '../session/scripts';
 import type { Viewer } from '../session/viewer';
 import RelationshipChangeset from '../utils/relationship-changeset';
 import {
   updateDatasForUserPairs,
   updateUndirectedRelationships,
 } from './relationship-updaters';
 
 export type MembershipRowToSave = {|
   +operation: 'save',
   +intent: 'join' | 'leave' | 'none',
   +userID: string,
   +threadID: string,
   +userNeedsFullThreadDetails: boolean,
   +permissions: ?ThreadPermissionsBlob,
   +permissionsForChildren: ?ThreadPermissionsBlob,
   // null role represents by "0"
   +role: string,
-  lastMessage?: number,
-  lastReadMessage?: number,
+  +unread?: boolean,
 |};
 type MembershipRowToDelete = {|
   +operation: 'delete',
   +intent: 'join' | 'leave' | 'none',
   +userID: string,
   +threadID: string,
 |};
 type MembershipRow = MembershipRowToSave | MembershipRowToDelete;
 type Changeset = {|
   +membershipRows: MembershipRow[],
   +relationshipChangeset: RelationshipChangeset,
 |};
 
 // 0 role means to remove the user from the thread
 // null role means to set the user to the default role
 // string role means to set the user to the role with that ID
 // -1 role means to set the user as a "ghost" (former member)
+type ChangeRoleOptions = {|
+  +setNewMembersToUnread?: boolean,
+|};
 async function changeRole(
   threadID: string,
   userIDs: $ReadOnlyArray<string>,
   role: string | -1 | 0 | null,
+  options?: ChangeRoleOptions,
 ): Promise<?Changeset> {
   const intent = role === -1 || role === 0 ? 'leave' : 'join';
+  const setNewMembersToUnread =
+    options?.setNewMembersToUnread && intent === 'join';
 
   const membershipQuery = SQL`
     SELECT m.user, m.role, m.permissions_for_children,
       pm.permissions_for_children AS permissions_from_parent,
       'existing' AS row_state
     FROM memberships m
     LEFT JOIN threads t ON t.id = m.thread
     LEFT JOIN memberships pm
       ON pm.thread = t.parent_thread_id AND pm.user = m.user
     WHERE m.thread = ${threadID}
     UNION SELECT pm.user, -1 AS role,
       NULL AS permissions_for_children,
       pm.permissions_for_children AS permissions_from_parent,
       'from_parent' AS row_state
     FROM threads t
     LEFT JOIN memberships pm ON pm.thread = t.parent_thread_id
     LEFT JOIN memberships m ON m.thread = t.id AND m.user = pm.user
     WHERE t.id = ${threadID} AND m.thread IS NULL
   `;
   const [[membershipResult], roleThreadResult] = await Promise.all([
     dbQuery(membershipQuery),
     changeRoleThreadQuery(threadID, role),
   ]);
   if (!roleThreadResult) {
     return null;
   }
 
   const roleInfo = new Map();
   for (const row of membershipResult) {
     if (!row.user) {
       continue;
     }
     const userID = row.user.toString();
     const oldPermissionsForChildren = JSON.parse(row.permissions_for_children);
     const permissionsFromParent = JSON.parse(row.permissions_from_parent);
     roleInfo.set(userID, {
       oldRole: row.role.toString(),
       oldPermissionsForChildren,
       permissionsFromParent,
       rowState: row.row_state,
     });
   }
 
   const membershipRows = [];
   const relationshipChangeset = new RelationshipChangeset();
   const toUpdateDescendants = new Map();
   const existingMemberIDs = [...new Set(roleInfo.keys())];
   relationshipChangeset.setAllRelationshipsExist(existingMemberIDs);
   for (const userID of userIDs) {
     let oldPermissionsForChildren = null;
     let permissionsFromParent = null;
     let hadMembershipRow = false;
     let oldRole;
     const userRoleInfo = roleInfo.get(userID);
     if (userRoleInfo) {
       hadMembershipRow = userRoleInfo.rowState === 'existing';
       oldRole = userRoleInfo.oldRole;
       if (hadMembershipRow && oldRole === roleThreadResult.roleColumnValue) {
         // If the old role is the same as the new one, we have nothing to update
         continue;
       } else if (Number(oldRole) > 0 && role === null) {
         // In the case where we're just trying to add somebody to a thread, if
         // they already have a role with a nonzero role then we don't need to do
         // anything
         continue;
       }
       oldPermissionsForChildren = userRoleInfo.oldPermissionsForChildren;
       permissionsFromParent = userRoleInfo.permissionsFromParent;
     }
 
     const permissions = makePermissionsBlob(
       roleThreadResult.rolePermissions,
       permissionsFromParent,
       threadID,
       roleThreadResult.threadType,
     );
     const permissionsForChildren = makePermissionsForChildrenBlob(permissions);
 
     if (permissions) {
       if (role === -1) {
         console.warn(
           `changeRole called for -1 role, but found non-null permissions for ` +
             `userID ${userID} and threadID ${threadID}`,
         );
       }
       const newRole =
         Number(roleThreadResult.roleColumnValue) >= 0
           ? roleThreadResult.roleColumnValue
           : '0';
       const userBecameMember =
         (!oldRole || Number(oldRole) <= 0) && Number(newRole) > 0;
       membershipRows.push({
         operation: 'save',
         intent,
         userID,
         threadID,
         userNeedsFullThreadDetails: userBecameMember,
         permissions,
         permissionsForChildren,
         role: newRole,
+        unread: userBecameMember && setNewMembersToUnread,
       });
     } else {
       membershipRows.push({
         operation: 'delete',
         intent,
         userID,
         threadID,
       });
     }
 
     if (permissions && !hadMembershipRow) {
       relationshipChangeset.setRelationshipsNeeded(userID, existingMemberIDs);
     }
 
     if (!_isEqual(permissionsForChildren)(oldPermissionsForChildren)) {
       toUpdateDescendants.set(userID, permissionsForChildren);
     }
   }
 
   if (toUpdateDescendants.size > 0) {
     const {
       membershipRows: descendantMembershipRows,
       relationshipChangeset: descendantRelationshipChangeset,
     } = await updateDescendantPermissions(threadID, toUpdateDescendants);
     membershipRows.push(...descendantMembershipRows);
     relationshipChangeset.addAll(descendantRelationshipChangeset);
   }
 
   return { membershipRows, relationshipChangeset };
 }
 
 type RoleThreadResult = {|
   +roleColumnValue: string,
   +threadType: ThreadType,
   +rolePermissions: ?ThreadRolePermissionsBlob,
 |};
 async function changeRoleThreadQuery(
   threadID: string,
   role: string | -1 | 0 | null,
 ): Promise<?RoleThreadResult> {
   if (role === 0) {
     const query = SQL`SELECT type FROM threads WHERE id = ${threadID}`;
     const [result] = await dbQuery(query);
     if (result.length === 0) {
       return null;
     }
     const row = result[0];
     return {
       roleColumnValue: '0',
       threadType: assertThreadType(row.type),
       rolePermissions: null,
     };
   } else if (role === -1) {
     const query = SQL`SELECT type FROM threads WHERE id = ${threadID}`;
     const [result] = await dbQuery(query);
     if (result.length === 0) {
       return null;
     }
     const row = result[0];
     return {
       roleColumnValue: '-1',
       threadType: assertThreadType(row.type),
       rolePermissions: null,
     };
   } else if (role !== null) {
     const query = SQL`
       SELECT t.type, r.permissions
       FROM threads t
       LEFT JOIN roles r ON r.id = ${role}
       WHERE t.id = ${threadID}
     `;
     const [result] = await dbQuery(query);
     if (result.length === 0) {
       return null;
     }
     const row = result[0];
     return {
       roleColumnValue: role,
       threadType: assertThreadType(row.type),
       rolePermissions: row.permissions,
     };
   } else {
     const query = SQL`
       SELECT t.type, t.default_role, r.permissions
       FROM threads t
       LEFT JOIN roles r ON r.id = t.default_role
       WHERE t.id = ${threadID}
     `;
     const [result] = await dbQuery(query);
     if (result.length === 0) {
       return null;
     }
     const row = result[0];
     return {
       roleColumnValue: row.default_role.toString(),
       threadType: assertThreadType(row.type),
       rolePermissions: row.permissions,
     };
   }
 }
 
 async function updateDescendantPermissions(
   initialParentThreadID: string,
   initialUsersToPermissionsFromParent: Map<string, ?ThreadPermissionsBlob>,
 ): Promise<Changeset> {
   const stack = [[initialParentThreadID, initialUsersToPermissionsFromParent]];
   const membershipRows = [];
   const relationshipChangeset = new RelationshipChangeset();
   while (stack.length > 0) {
     const [parentThreadID, usersToPermissionsFromParent] = stack.shift();
 
     const query = SQL`
       SELECT t.id, m.user, t.type,
         r.permissions AS role_permissions, m.permissions,
         m.permissions_for_children, m.role
       FROM threads t
       LEFT JOIN memberships m ON m.thread = t.id
       LEFT JOIN roles r ON r.id = m.role
       WHERE t.parent_thread_id = ${parentThreadID}
     `;
     const [result] = await dbQuery(query);
 
     const childThreadInfos = new Map();
     for (const row of result) {
       const threadID = row.id.toString();
       if (!childThreadInfos.has(threadID)) {
         childThreadInfos.set(threadID, {
           threadType: assertThreadType(row.type),
           userInfos: new Map(),
         });
       }
       if (!row.user) {
         continue;
       }
       const childThreadInfo = childThreadInfos.get(threadID);
       invariant(childThreadInfo, `value should exist for key ${threadID}`);
       const userID = row.user.toString();
       childThreadInfo.userInfos.set(userID, {
         role: row.role.toString(),
         rolePermissions: row.role_permissions,
         permissions: row.permissions,
         permissionsForChildren: row.permissions_for_children,
       });
     }
 
     for (const [threadID, childThreadInfo] of childThreadInfos) {
       const userInfos = childThreadInfo.userInfos;
       const existingMemberIDs = [...userInfos.keys()];
       relationshipChangeset.setAllRelationshipsExist(existingMemberIDs);
       const usersForNextLayer = new Map();
       for (const [
         userID,
         permissionsFromParent,
       ] of usersToPermissionsFromParent) {
         const userInfo = userInfos.get(userID);
         const role =
           userInfo && Number(userInfo.role) > 0 ? userInfo.role : '0';
         const rolePermissions = userInfo?.rolePermissions;
         const oldPermissions = userInfo?.permissions;
         const oldPermissionsForChildren = userInfo
           ? userInfo.permissionsForChildren
           : null;
 
         const permissions = makePermissionsBlob(
           rolePermissions,
           permissionsFromParent,
           threadID,
           childThreadInfo.threadType,
         );
         if (_isEqual(permissions)(oldPermissions)) {
           // This thread and all of its children need no updates, since its
           // permissions are unchanged by this operation
           continue;
         }
         const permissionsForChildren = makePermissionsForChildrenBlob(
           permissions,
         );
 
         if (permissions) {
           membershipRows.push({
             operation: 'save',
             intent: 'none',
             userID,
             threadID,
             userNeedsFullThreadDetails: false,
             permissions,
             permissionsForChildren,
             role,
           });
         } else {
           membershipRows.push({
             operation: 'delete',
             intent: 'none',
             userID,
             threadID,
           });
         }
 
         if (permissions && !userInfo) {
           // If there was no membership row before, and we are creating one,
           // we'll need to make sure the new member has a relationship row with
           // each existing member. We assume whoever called us will handle
           // making sure the set of new members all have relationship rows with
           // each other.
           relationshipChangeset.setRelationshipsNeeded(
             userID,
             existingMemberIDs,
           );
         }
 
         if (!_isEqual(permissionsForChildren)(oldPermissionsForChildren)) {
           usersForNextLayer.set(userID, permissionsForChildren);
         }
       }
       if (usersForNextLayer.size > 0) {
         stack.push([threadID, usersForNextLayer]);
       }
     }
   }
   return { membershipRows, relationshipChangeset };
 }
 
 async function recalculateThreadPermissions(
   threadID: string,
   threadType: ThreadType,
 ): Promise<Changeset> {
   const selectQuery = SQL`
     SELECT m.user, m.role, m.permissions, m.permissions_for_children,
       pm.permissions_for_children AS permissions_from_parent,
       r.permissions AS role_permissions, 'existing' AS row_state
     FROM memberships m
     LEFT JOIN threads t ON t.id = m.thread
     LEFT JOIN roles r ON r.id = m.role
     LEFT JOIN memberships pm ON pm.thread = t.parent_thread_id
       AND pm.user = m.user
     WHERE m.thread = ${threadID}
     UNION SELECT pm.user, -1 AS role, NULL AS permissions,
       NULL AS permissions_for_children,
       pm.permissions_for_children AS permissions_from_parent,
       NULL AS role_permissions, 'from_parent' AS row_state
     FROM threads t
     LEFT JOIN memberships pm ON pm.thread = t.parent_thread_id
     LEFT JOIN memberships m ON m.thread = t.id AND m.user = pm.user
     WHERE t.id = ${threadID} AND m.thread IS NULL
   `;
   const [selectResult] = await dbQuery(selectQuery);
 
   const membershipRows = [];
   const relationshipChangeset = new RelationshipChangeset();
   const toUpdateDescendants = new Map();
   const existingMemberIDs = selectResult
     .filter((row) => row.user && row.row_state === 'existing')
     .map((row) => row.user.toString());
   relationshipChangeset.setAllRelationshipsExist(existingMemberIDs);
 
   for (const row of selectResult) {
     if (!row.user) {
       continue;
     }
     const userID = row.user.toString();
     const role = row.role >= 0 ? row.role.toString() : '0';
     const oldPermissions = JSON.parse(row.permissions);
     const oldPermissionsForChildren = JSON.parse(row.permissions_for_children);
     const permissionsFromParent = JSON.parse(row.permissions_from_parent);
     const rolePermissions = JSON.parse(row.role_permissions);
     const hadMembershipRow = row.row_state === 'existing';
 
     const permissions = makePermissionsBlob(
       rolePermissions,
       permissionsFromParent,
       threadID,
       threadType,
     );
     if (_isEqual(permissions)(oldPermissions)) {
       // This thread and all of its children need no updates, since its
       // permissions are unchanged by this operation
       continue;
     }
     const permissionsForChildren = makePermissionsForChildrenBlob(permissions);
 
     if (permissions) {
       membershipRows.push({
         operation: 'save',
         intent: 'none',
         userID,
         threadID,
         userNeedsFullThreadDetails: false,
         permissions,
         permissionsForChildren,
         role,
       });
     } else {
       membershipRows.push({
         operation: 'delete',
         intent: 'none',
         userID,
         threadID,
       });
     }
 
     if (permissions && !hadMembershipRow) {
       // If there was no membership row before, and we are creating one,
       // we'll need to make sure the new member has a relationship row with
       // each existing member. We assume all the new members already have
       // relationship rows with each other, since they must all share the same
       // parent thread.
       relationshipChangeset.setRelationshipsNeeded(userID, existingMemberIDs);
     }
 
     if (!_isEqual(permissionsForChildren)(oldPermissionsForChildren)) {
       toUpdateDescendants.set(userID, permissionsForChildren);
     }
   }
 
   if (toUpdateDescendants.size > 0) {
     const {
       membershipRows: descendantMembershipRows,
       relationshipChangeset: descendantRelationshipChangeset,
     } = await updateDescendantPermissions(threadID, toUpdateDescendants);
     membershipRows.push(...descendantMembershipRows);
     relationshipChangeset.addAll(descendantRelationshipChangeset);
   }
 
   return { membershipRows, relationshipChangeset };
 }
 
 const defaultSubscriptionString = JSON.stringify({
   home: false,
   pushNotifs: false,
 });
 const joinSubscriptionString = JSON.stringify({ home: true, pushNotifs: true });
 
 async function saveMemberships(toSave: $ReadOnlyArray<MembershipRowToSave>) {
   if (toSave.length === 0) {
     return;
   }
 
   const time = Date.now();
   const insertRows = [];
   for (const rowToSave of toSave) {
-    const lastMessage = rowToSave.lastMessage ?? 0;
-    const lastReadMessage = rowToSave.lastReadMessage ?? 0;
     insertRows.push([
       rowToSave.userID,
       rowToSave.threadID,
       rowToSave.role,
       time,
       rowToSave.intent === 'join'
         ? joinSubscriptionString
         : defaultSubscriptionString,
       rowToSave.permissions ? JSON.stringify(rowToSave.permissions) : null,
       rowToSave.permissionsForChildren
         ? JSON.stringify(rowToSave.permissionsForChildren)
         : null,
-      lastMessage,
-      lastReadMessage,
+      rowToSave.unread ? 1 : 0,
+      0,
     ]);
   }
 
   // Logic below will only update an existing membership row's `subscription`
   // column if the user is either joining or leaving the thread. That means
   // there's no way to use this function to update a user's subscription without
   // also making them join or leave the thread. The reason we do this is because
   // we need to specify a value for `subscription` here, as it's a non-null
   // column and this is an INSERT, but we don't want to require people to have
   // to know the current `subscription` when they're just using this function to
   // update the permissions of an existing membership row.
   const query = SQL`
     INSERT INTO memberships (user, thread, role, creation_time, subscription,
       permissions, permissions_for_children, last_message, last_read_message)
     VALUES ${insertRows}
     ON DUPLICATE KEY UPDATE
       subscription = IF(
         (role <= 0 AND VALUES(role) > 0)
           OR (role > 0 AND VALUES(role) <= 0),
         VALUES(subscription),
         subscription
       ),
       role = VALUES(role),
       permissions = VALUES(permissions),
       permissions_for_children = VALUES(permissions_for_children)
   `;
   await dbQuery(query);
 }
 
 async function deleteMemberships(
   toDelete: $ReadOnlyArray<MembershipRowToDelete>,
 ) {
   if (toDelete.length === 0) {
     return;
   }
 
   const time = Date.now();
   const insertRows = toDelete.map((rowToDelete) => [
     rowToDelete.userID,
     rowToDelete.threadID,
     -1,
     time,
     defaultSubscriptionString,
     null,
     null,
     0,
     0,
   ]);
 
   const query = SQL`
     INSERT INTO memberships (user, thread, role, creation_time, subscription,
       permissions, permissions_for_children, last_message, last_read_message)
     VALUES ${insertRows}
     ON DUPLICATE KEY UPDATE
       role = -1,
       permissions = NULL,
       permissions_for_children = NULL,
       subscription = ${defaultSubscriptionString},
       last_message = 0,
       last_read_message = 0
   `;
   await dbQuery(query);
 }
 
 // Specify non-empty changedThreadIDs to force updates to be generated for those
 // threads, presumably for reasons not covered in the changeset. calendarQuery
 // only needs to be specified if a JOIN_THREAD update will be generated for the
 // viewer, in which case it's necessary for knowing the set of entries to fetch.
 type ChangesetCommitResult = {|
   ...FetchThreadInfosResult,
   viewerUpdates: $ReadOnlyArray<UpdateInfo>,
   userInfos: { [id: string]: AccountUserInfo },
 |};
 async function commitMembershipChangeset(
   viewer: Viewer,
   changeset: Changeset,
   {
     changedThreadIDs = new Set(),
     calendarQuery,
     updatesForCurrentSession = 'return',
   }: {|
     changedThreadIDs?: Set<string>,
     calendarQuery?: ?CalendarQuery,
     updatesForCurrentSession?: UpdatesForCurrentSession,
   |} = {},
 ): Promise<ChangesetCommitResult> {
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
   const { membershipRows, relationshipChangeset } = changeset;
 
   const membershipRowMap = new Map();
   for (const row of membershipRows) {
     const { userID, threadID } = row;
     changedThreadIDs.add(threadID);
 
     const pairString = `${userID}|${threadID}`;
     const existing = membershipRowMap.get(pairString);
     invariant(
       !existing || existing.intent === 'none' || row.intent === 'none',
       `multiple intents provided for ${pairString}`,
     );
     if (!existing || existing.intent === 'none') {
       membershipRowMap.set(pairString, row);
     }
   }
 
   const toSave = [],
     toDelete = [],
     rescindPromises = [];
   for (const row of membershipRowMap.values()) {
     if (
       row.operation === 'delete' ||
       (row.operation === 'save' && Number(row.role) <= 0)
     ) {
       const { userID, threadID } = row;
       rescindPromises.push(
         rescindPushNotifs(
           SQL`n.thread = ${threadID} AND n.user = ${userID}`,
           SQL`IF(m.thread = ${threadID}, NULL, m.thread)`,
         ),
       );
     }
     if (row.operation === 'delete') {
       toDelete.push(row);
     } else {
       toSave.push(row);
     }
   }
 
   const threadsToSavedUsers = new Map();
   for (const row of membershipRowMap.values()) {
     const { userID, threadID } = row;
     let savedUsers = threadsToSavedUsers.get(threadID);
     if (!savedUsers) {
       savedUsers = [];
       threadsToSavedUsers.set(threadID, savedUsers);
     }
     savedUsers.push(userID);
   }
   for (const savedUsers of threadsToSavedUsers.values()) {
     relationshipChangeset.setAllRelationshipsNeeded(savedUsers);
   }
   const relationshipRows = relationshipChangeset.getRows();
 
   await Promise.all([
     saveMemberships(toSave),
     deleteMemberships(toDelete),
     updateUndirectedRelationships(relationshipRows),
     ...rescindPromises,
   ]);
 
   // We fetch all threads here because old clients still expect the full list of
   // threads on most thread operations. Once verifyClientSupported gates on
   // codeVersion 62, we can add a WHERE clause on changedThreadIDs here
   const serverThreadInfoFetchResult = await fetchServerThreadInfos();
   const { threadInfos: serverThreadInfos } = serverThreadInfoFetchResult;
 
   const time = Date.now();
   const updateDatas = updateDatasForUserPairs(
     relationshipRows.map(({ user1, user2 }) => [user1, user2]),
   );
   for (const changedThreadID of changedThreadIDs) {
     const serverThreadInfo = serverThreadInfos[changedThreadID];
     for (const memberInfo of serverThreadInfo.members) {
       const pairString = `${memberInfo.id}|${serverThreadInfo.id}`;
       const membershipRow = membershipRowMap.get(pairString);
       if (
         membershipRow &&
         (membershipRow.operation === 'delete' ||
           membershipRow.userNeedsFullThreadDetails)
       ) {
         continue;
       }
       updateDatas.push({
         type: updateTypes.UPDATE_THREAD,
         userID: memberInfo.id,
         time,
         threadID: changedThreadID,
       });
     }
   }
   for (const row of membershipRowMap.values()) {
     const { userID, threadID } = row;
     if (row.operation === 'delete') {
       updateDatas.push({
         type: updateTypes.DELETE_THREAD,
         userID,
         time,
         threadID,
       });
     } else if (row.userNeedsFullThreadDetails) {
       updateDatas.push({
         type: updateTypes.JOIN_THREAD,
         userID,
         time,
         threadID,
       });
     }
   }
 
   const threadInfoFetchResult = rawThreadInfosFromServerThreadInfos(
     viewer,
     serverThreadInfoFetchResult,
   );
   const { viewerUpdates, userInfos } = await createUpdates(updateDatas, {
     viewer,
     calendarQuery,
     ...threadInfoFetchResult,
     updatesForCurrentSession,
   });
 
   return {
     ...threadInfoFetchResult,
     userInfos,
     viewerUpdates,
   };
 }
 
-function setJoinsToUnread(
-  rows: MembershipRow[],
-  exceptViewerID: string,
-  exceptThreadID: string,
-) {
-  for (const row of rows) {
-    if (
-      row.operation === 'save' &&
-      (row.userID !== exceptViewerID || row.threadID !== exceptThreadID)
-    ) {
-      row.lastMessage = 1;
-      row.lastReadMessage = 0;
-    }
-  }
-}
-
 async function recalculateAllThreadPermissions() {
   const getAllThreads = SQL`SELECT id, type FROM threads`;
   const [result] = await dbQuery(getAllThreads);
 
   // We handle each thread one-by-one to avoid a situation where a permission
   // calculation for a child thread, done during a call to
   // recalculateThreadPermissions for the parent thread, can be incorrectly
   // overriden by a call to recalculateThreadPermissions for the child thread.
   // If the changeset resulting from the parent call isn't committed before the
   // calculation is done for the child, the calculation done for the child can
   // be incorrect.
   const viewer = createScriptViewer(bots.squadbot.userID);
   for (const row of result) {
     const threadID = row.id.toString();
     const threadType = assertThreadType(row.type);
     const changeset = await recalculateThreadPermissions(threadID, threadType);
     await commitMembershipChangeset(viewer, changeset);
   }
 }
 
 export {
   changeRole,
   recalculateThreadPermissions,
   saveMemberships,
   commitMembershipChangeset,
-  setJoinsToUnread,
   recalculateAllThreadPermissions,
 };
diff --git a/server/src/updaters/thread-updaters.js b/server/src/updaters/thread-updaters.js
index f3ec24fc9..e5c889dcf 100644
--- a/server/src/updaters/thread-updaters.js
+++ b/server/src/updaters/thread-updaters.js
@@ -1,744 +1,743 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { filteredThreadIDs } from 'lib/selectors/calendar-filter-selectors';
 import {
   threadHasAdminRole,
   roleIsAdminRole,
   viewerIsMember,
   getThreadTypeParentRequirement,
   threadMemberHasPermission,
 } from 'lib/shared/thread-utils';
 import { hasMinCodeVersion } from 'lib/shared/version-utils';
 import type { Shape } from 'lib/types/core';
 import { messageTypes, defaultNumberPerThread } from 'lib/types/message-types';
 import { userRelationshipStatus } from 'lib/types/relationship-types';
 import {
   type RoleChangeRequest,
   type ChangeThreadSettingsResult,
   type RemoveMembersRequest,
   type LeaveThreadRequest,
   type LeaveThreadResult,
   type UpdateThreadRequest,
   type ServerThreadJoinRequest,
   type ThreadJoinResult,
   threadPermissions,
   threadTypes,
 } from 'lib/types/thread-types';
 import { updateTypes } from 'lib/types/update-types';
 import { ServerError } from 'lib/utils/errors';
 import { promiseAll } from 'lib/utils/promises';
 import { firstLine } from 'lib/utils/string-utils';
 
 import createMessages from '../creators/message-creator';
 import { createUpdates } from '../creators/update-creator';
 import { dbQuery, SQL } from '../database/database';
 import { fetchEntryInfos } from '../fetchers/entry-fetchers';
 import { fetchMessageInfos } from '../fetchers/message-fetchers';
 import {
   fetchThreadInfos,
   fetchServerThreadInfos,
 } from '../fetchers/thread-fetchers';
 import {
   checkThreadPermission,
   viewerIsMember as fetchViewerIsMember,
   checkThread,
 } from '../fetchers/thread-permission-fetchers';
 import {
   verifyUserIDs,
   verifyUserOrCookieIDs,
   fetchKnownUserInfos,
 } from '../fetchers/user-fetchers';
 import type { Viewer } from '../session/viewer';
 import RelationshipChangeset from '../utils/relationship-changeset';
 import { updateRoles } from './role-updaters';
 import {
   changeRole,
   recalculateThreadPermissions,
   commitMembershipChangeset,
-  setJoinsToUnread,
 } from './thread-permission-updaters';
 
 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);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   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);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   const { threadInfos, viewerUpdates } = await commitMembershipChangeset(
     viewer,
     changeset,
   );
 
   const messageData = {
     type: messageTypes.REMOVE_MEMBERS,
     threadID: request.threadID,
     creatorID: viewerID,
     time: Date.now(),
     removedUserIDs: actualMemberIDs,
   };
   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 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) || !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);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
   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,
 |}>;
 
 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 validationPromises = {};
 
   const changedFields = {};
   const sqlUpdate = {};
   const untrimmedName = request.changes.name;
   if (untrimmedName !== undefined && untrimmedName !== null) {
     const name = firstLine(untrimmedName);
     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 (
     !viewer.isScriptViewer &&
     (threadType === threadTypes.PERSONAL ||
       threadType === threadTypes.PRIVATE ||
       threadType === threadTypes.SIDEBAR)
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const newMemberIDs =
     request.changes.newMemberIDs && request.changes.newMemberIDs.length > 0
       ? [...request.changes.newMemberIDs]
       : null;
 
   if (Object.keys(sqlUpdate).length === 0 && !newMemberIDs) {
     throw new ServerError('invalid_parameters');
   }
 
   if (newMemberIDs) {
     validationPromises.fetchNewMembers = fetchKnownUserInfos(
       viewer,
       newMemberIDs,
     );
   }
 
   validationPromises.serverThreadInfos = fetchServerThreadInfos(
     SQL`t.id = ${request.threadID}`,
   );
 
   const checks = [];
   if (
     sqlUpdate.name !== undefined ||
     sqlUpdate.description !== undefined ||
     sqlUpdate.color !== undefined
   ) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.EDIT_THREAD,
     });
   }
   if (parentThreadID !== undefined || sqlUpdate.type !== undefined) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.EDIT_PERMISSIONS,
     });
   }
   if (newMemberIDs) {
     checks.push({
       check: 'permission',
       permission: threadPermissions.ADD_MEMBERS,
     });
   }
 
   validationPromises.hasNecessaryPermissions = checkThread(
     viewer,
     request.threadID,
     checks,
   );
 
   const {
     fetchNewMembers,
     serverThreadInfos,
     hasNecessaryPermissions,
   } = await promiseAll(validationPromises);
 
   const serverThreadInfo = serverThreadInfos.threadInfos[request.threadID];
   if (!serverThreadInfo) {
     throw new ServerError('internal_error');
   }
 
   if (!hasNecessaryPermissions) {
     throw new ServerError('invalid_credentials');
   }
 
   // Threads with source message should be visible to everyone, but we can't
   // guarantee it for CHAT_SECRET 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 === threadTypes.CHAT_SECRET &&
     serverThreadInfo.sourceMessageID
   ) {
     throw new ServerError('invalid_parameters');
   }
 
   const oldThreadType = serverThreadInfo.type;
   const oldParentThreadID = serverThreadInfo.parentThreadID;
 
   const nextThreadType =
     threadType !== null && threadType !== undefined
       ? threadType
       : oldThreadType;
   let nextParentThreadID =
     parentThreadID !== undefined ? parentThreadID : oldParentThreadID;
 
   // You can't change the parent thread of a SIDEBAR
   if (nextThreadType === threadTypes.SIDEBAR && parentThreadID !== undefined) {
     throw new ServerError('invalid_parameters');
   }
 
   // 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');
   }
 
   if (
     nextParentThreadID &&
     (nextParentThreadID !== oldParentThreadID ||
       (nextThreadType === threadTypes.SIDEBAR) !==
         (oldThreadType === threadTypes.SIDEBAR))
   ) {
     const hasParentPermission = await checkThreadPermission(
       viewer,
       nextParentThreadID,
       nextThreadType === threadTypes.SIDEBAR
         ? threadPermissions.CREATE_SIDEBARS
         : threadPermissions.CREATE_SUBTHREADS,
     );
     if (!hasParentPermission) {
       throw new ServerError('invalid_parameters');
     }
   }
 
   if (fetchNewMembers) {
     invariant(newMemberIDs, 'should be set');
     const newIDs = newMemberIDs; // for Flow
     for (const newMemberID of newIDs) {
       if (!fetchNewMembers[newMemberID]) {
         if (!forceAddMembers) {
           throw new ServerError('invalid_credentials');
         } else if (nextThreadType === threadTypes.SIDEBAR) {
           throw new ServerError('invalid_thread_type');
         } else {
           continue;
         }
       }
       const { relationshipStatus } = fetchNewMembers[newMemberID];
       if (
         relationshipStatus === userRelationshipStatus.FRIEND &&
         nextThreadType !== threadTypes.SIDEBAR
       ) {
         continue;
       } else if (
         relationshipStatus === userRelationshipStatus.BLOCKED_BY_VIEWER ||
         relationshipStatus === userRelationshipStatus.BLOCKED_VIEWER ||
         relationshipStatus === userRelationshipStatus.BOTH_BLOCKED
       ) {
         throw new ServerError('invalid_credentials');
       } else if (
         threadMemberHasPermission(
           serverThreadInfo,
           newMemberID,
           threadPermissions.KNOW_OF,
         )
       ) {
         continue;
       } else if (forceAddMembers && nextThreadType !== threadTypes.SIDEBAR) {
         continue;
       }
       throw new ServerError('invalid_credentials');
     }
   }
 
   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 rolesNeedUpdate = forceUpdateRoot || nextThreadType !== oldThreadType;
   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);
+      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,
         nextThreadType,
       );
     })();
   }
 
   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);
   }
   if (addMembersChangeset) {
     const {
       membershipRows: addMembersMembershipRows,
       relationshipChangeset: addMembersRelationshipChangeset,
     } = addMembersChangeset;
-    setJoinsToUnread(addMembersMembershipRows, viewer.userID, request.threadID);
     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(),
     },
   );
 
   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 (newMemberIDs) {
     messageDatas.push({
       type: messageTypes.ADD_MEMBERS,
       threadID: request.threadID,
       creatorID: viewer.userID,
       time,
       addedUserIDs: newMemberIDs,
     });
   }
   const 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 (isMember || !hasPermission) {
     throw new ServerError('invalid_parameters');
   }
 
   const { calendarQuery } = request;
   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);
   if (!changeset) {
     throw new ServerError('unknown_error');
   }
-  setJoinsToUnread(changeset.membershipRows, viewer.userID, request.threadID);
 
   const membershipResult = await commitMembershipChangeset(viewer, changeset, {
     calendarQuery,
   });
 
   const messageData = {
     type: messageTypes.JOIN_THREAD,
     threadID: request.threadID,
     creatorID: viewer.userID,
     time: Date.now(),
   };
   await createMessages(viewer, [messageData]);
 
   const threadSelectionCriteria = {
     threadCursors: { [request.threadID]: false },
   };
   const [fetchMessagesResult, fetchEntriesResult] = await Promise.all([
     fetchMessageInfos(viewer, threadSelectionCriteria, 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 (!hasMinCodeVersion(viewer.platformDetails, 62)) {
     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,
 };