diff --git a/keyserver/src/creators/update-creator.js b/keyserver/src/creators/update-creator.js
index a59034db2..0250827b5 100644
--- a/keyserver/src/creators/update-creator.js
+++ b/keyserver/src/creators/update-creator.js
@@ -1,641 +1,631 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { nonThreadCalendarFilters } from 'lib/selectors/calendar-filter-selectors.js';
 import {
   keyForUpdateData,
   keyForUpdateInfo,
   rawUpdateInfoFromUpdateData,
 } from 'lib/shared/update-utils.js';
 import type {
   UpdateInfosRawData,
   DeleteConditionType,
 } from 'lib/shared/updates/update-spec.js';
 import { updateSpecs } from 'lib/shared/updates/update-specs.js';
 import {
   type CalendarQuery,
   defaultCalendarQuery,
 } from 'lib/types/entry-types.js';
 import {
   defaultNumberPerThread,
   type MessageSelectionCriteria,
 } from 'lib/types/message-types.js';
 import {
   type UpdateTarget,
   redisMessageTypes,
   type NewUpdatesRedisMessage,
 } from 'lib/types/redis-types.js';
 import type { RawThreadInfo } from 'lib/types/thread-types.js';
 import { updateTypes } from 'lib/types/update-types-enum.js';
 import {
   type ServerUpdateInfo,
   type UpdateData,
   type RawUpdateInfo,
   type CreateUpdatesResult,
 } from 'lib/types/update-types.js';
 import type { UserInfos } from 'lib/types/user-types.js';
 import { promiseAll } from 'lib/utils/promises.js';
 
 import createIDs from './id-creator.js';
 import { dbQuery, SQL, mergeAndConditions } from '../database/database.js';
 import type { SQLStatementType } from '../database/types.js';
 import { deleteUpdatesByConditions } from '../deleters/update-deleters.js';
 import {
   fetchEntryInfos,
   fetchEntryInfosByID,
 } from '../fetchers/entry-fetchers.js';
 import { fetchMessageInfos } from '../fetchers/message-fetchers.js';
 import { fetchThreadInfos } from '../fetchers/thread-fetchers.js';
 import {
   fetchKnownUserInfos,
   fetchCurrentUserInfo,
 } from '../fetchers/user-fetchers.js';
 import type { Viewer } from '../session/viewer.js';
 import { channelNameForUpdateTarget, publisher } from '../socket/redis.js';
 
 export type UpdatesForCurrentSession =
   // This is the default if no Viewer is passed, or if an isSocket Viewer is
   // passed in. We will broadcast to all valid sessions via Redis and return
   // nothing to the caller, relying on the current session's Redis listener to
   // pick up the updates and deliver them asynchronously.
   | 'broadcast'
   // This is the default if a non-isSocket Viewer is passed in. We avoid
   // broadcasting the update to the current session, and instead return the
   // update to the caller, who will handle delivering it to the client.
   | 'return'
   // This means we ignore any updates destined for the current session.
   // Presumably the caller knows what they are doing and has a different way of
   // communicating the relevant information to the client.
   | 'ignore';
 
 type DeleteCondition = {
   +userID: string,
   +target: ?string,
   +types: DeleteConditionType,
 };
 
 export type ViewerInfo =
   | {
       viewer: Viewer,
       calendarQuery?: ?CalendarQuery,
       updatesForCurrentSession?: UpdatesForCurrentSession,
     }
   | {
       viewer: Viewer,
       calendarQuery: ?CalendarQuery,
       updatesForCurrentSession?: UpdatesForCurrentSession,
       threadInfos: { +[id: string]: RawThreadInfo },
     };
 const defaultUpdateCreationResult = { viewerUpdates: [], userInfos: {} };
 const sortFunction = (
   a: UpdateData | ServerUpdateInfo,
   b: UpdateData | ServerUpdateInfo,
 ) => a.time - b.time;
 const deleteUpdatesBatchSize = 500;
 
 // Creates rows in the updates table based on the inputed updateDatas. Returns
 // UpdateInfos pertaining to the provided viewerInfo, as well as related
 // UserInfos. If no viewerInfo is provided, no UpdateInfos will be returned. And
 // the update row won't have an updater column, meaning no session will be
 // excluded from the update.
 async function createUpdates(
   updateDatas: $ReadOnlyArray<UpdateData>,
   passedViewerInfo?: ?ViewerInfo,
 ): Promise<CreateUpdatesResult> {
   if (updateDatas.length === 0) {
     return defaultUpdateCreationResult;
   }
 
   // viewer.session will throw for a script Viewer
   let viewerInfo = passedViewerInfo;
   if (
     viewerInfo &&
     (viewerInfo.viewer.isScriptViewer || !viewerInfo.viewer.loggedIn)
   ) {
     viewerInfo = null;
   }
 
   const sortedUpdateDatas = [...updateDatas].sort(sortFunction);
 
   const filteredUpdateDatas: UpdateData[] = [];
   const keyedUpdateDatas: Map<string, UpdateData[]> = new Map();
   for (const updateData of sortedUpdateDatas) {
     const key = keyForUpdateData(updateData);
     if (!key) {
       filteredUpdateDatas.push(updateData);
       continue;
     }
     const conditionKey = `${updateData.userID}|${key}`;
 
     const deleteCondition = getDeleteCondition(updateData);
     invariant(
       deleteCondition,
       `updateData of type ${updateData.type} has conditionKey ` +
         `${conditionKey} but no deleteCondition`,
     );
 
     const curUpdateDatas = keyedUpdateDatas.get(conditionKey);
     if (!curUpdateDatas) {
       keyedUpdateDatas.set(conditionKey, [updateData]);
       continue;
     }
 
     const filteredCurrent = curUpdateDatas.filter(curUpdateData =>
       filterOnDeleteCondition(curUpdateData, deleteCondition),
     );
     if (filteredCurrent.length === 0) {
       keyedUpdateDatas.set(conditionKey, [updateData]);
       continue;
     }
 
     const isNewUpdateDataFiltered = !filteredCurrent.every(curUpdateData => {
       const curDeleteCondition = getDeleteCondition(curUpdateData);
       invariant(
         curDeleteCondition,
         `updateData of type ${curUpdateData.type} is in keyedUpdateDatas ` +
           "but doesn't have a deleteCondition",
       );
       return filterOnDeleteCondition(updateData, curDeleteCondition);
     });
     if (!isNewUpdateDataFiltered) {
       filteredCurrent.push(updateData);
     }
     keyedUpdateDatas.set(conditionKey, filteredCurrent);
   }
 
   for (const keyUpdateDatas of keyedUpdateDatas.values()) {
     filteredUpdateDatas.push(...keyUpdateDatas);
   }
   const ids = await createIDs('updates', filteredUpdateDatas.length);
 
   let updatesForCurrentSession =
     viewerInfo && viewerInfo.updatesForCurrentSession;
   if (!updatesForCurrentSession && viewerInfo) {
     updatesForCurrentSession = viewerInfo.viewer.isSocket
       ? 'broadcast'
       : 'return';
   } else if (!updatesForCurrentSession) {
     updatesForCurrentSession = 'broadcast';
   }
   const dontBroadcastSession =
     updatesForCurrentSession !== 'broadcast' && viewerInfo
       ? viewerInfo.viewer.session
       : null;
 
   const publishInfos: Map<string, PublishInfo> = new Map();
   const viewerRawUpdateInfos: RawUpdateInfo[] = [];
   const insertRows: (?(number | string))[][] = [];
   const earliestTime: Map<string, number> = new Map();
   for (let i = 0; i < filteredUpdateDatas.length; i++) {
     const updateData = filteredUpdateDatas[i];
 
     const target = getTargetFromUpdateData(updateData);
     const rawUpdateInfo = rawUpdateInfoFromUpdateData(updateData, ids[i]);
 
     if (!target || !dontBroadcastSession || target !== dontBroadcastSession) {
       const updateTarget = target
         ? { userID: updateData.userID, sessionID: target }
         : { userID: updateData.userID };
       const channelName = channelNameForUpdateTarget(updateTarget);
       let publishInfo = publishInfos.get(channelName);
       if (!publishInfo) {
         publishInfo = { updateTarget, rawUpdateInfos: [] };
         publishInfos.set(channelName, publishInfo);
       }
       publishInfo.rawUpdateInfos.push(rawUpdateInfo);
     }
 
     if (
       updatesForCurrentSession === 'return' &&
       viewerInfo &&
       updateData.userID === viewerInfo.viewer.id &&
       (!target || target === viewerInfo.viewer.session)
     ) {
       viewerRawUpdateInfos.push(rawUpdateInfo);
     }
 
     if (viewerInfo && target && viewerInfo.viewer.session === target) {
       // In the case where this update is being created only for the current
       // session, there's no reason to insert a row into the updates table
       continue;
     }
 
     const content =
       updateSpecs[updateData.type].updateContentForServerDB(updateData);
 
     const key = keyForUpdateData(updateData);
     if (key) {
       const conditionKey = `${updateData.userID}|${key}`;
       const currentEarliestTime = earliestTime.get(conditionKey);
       if (!currentEarliestTime || updateData.time < currentEarliestTime) {
         earliestTime.set(conditionKey, updateData.time);
       }
     }
 
     const insertRow = [
       ids[i],
       updateData.userID,
       updateData.type,
       key,
       content,
       updateData.time,
       dontBroadcastSession,
       target,
     ];
     insertRows.push(insertRow);
   }
 
   type DeleteUpdatesConditions = {
     key: string,
     target?: string,
     types?: number[],
     time?: number,
   };
   const usersByConditions: Map<
     string,
     {
       conditions: DeleteUpdatesConditions,
       users: Set<string>,
     },
   > = new Map();
   for (const [conditionKey, keyUpdateDatas] of keyedUpdateDatas) {
     const deleteConditionByTarget: Map<?string, DeleteCondition> = new Map();
     for (const updateData of keyUpdateDatas) {
       const deleteCondition = getDeleteCondition(updateData);
       invariant(
         deleteCondition,
         `updateData of type ${updateData.type} is in keyedUpdateDatas but ` +
           "doesn't have a deleteCondition",
       );
       const { target, types } = deleteCondition;
 
       const existingDeleteCondition = deleteConditionByTarget.get(target);
       if (!existingDeleteCondition) {
         deleteConditionByTarget.set(target, deleteCondition);
         continue;
       }
 
       const existingTypes = existingDeleteCondition.types;
       if (existingTypes === 'all_types') {
         continue;
       } else if (types === 'all_types') {
         deleteConditionByTarget.set(target, deleteCondition);
         continue;
       }
 
       const mergedTypes = new Set([...types, ...existingTypes]);
       deleteConditionByTarget.set(target, {
         ...deleteCondition,
         types: mergedTypes,
       });
     }
 
     for (const deleteCondition of deleteConditionByTarget.values()) {
       const { userID, target, types } = deleteCondition;
       const key = conditionKey.split('|')[1];
       const conditions: DeleteUpdatesConditions = { key };
       if (target) {
         conditions.target = target;
       }
       if (types !== 'all_types') {
         invariant(types.size > 0, 'deleteCondition had empty types set');
         conditions.types = [...types];
       }
       const earliestTimeForCondition = earliestTime.get(conditionKey);
       if (earliestTimeForCondition) {
         conditions.time = earliestTimeForCondition;
       }
 
       const conditionsKey = JSON.stringify(conditions);
       if (!usersByConditions.has(conditionsKey)) {
         usersByConditions.set(conditionsKey, {
           conditions,
           users: new Set(),
         });
       }
       usersByConditions.get(conditionsKey)?.users.add(userID);
     }
   }
 
   const deleteSQLConditions: SQLStatementType[] = [];
   for (const { conditions, users } of usersByConditions.values()) {
     const sqlConditions = [
       SQL`u.user IN (${[...users]})`,
       SQL`u.key = ${conditions.key}`,
     ];
     if (conditions.target) {
       sqlConditions.push(SQL`u.target = ${conditions.target}`);
     }
     if (conditions.types) {
       sqlConditions.push(SQL`u.type IN (${conditions.types})`);
     }
     if (conditions.time) {
       sqlConditions.push(SQL`u.time < ${conditions.time}`);
     }
     deleteSQLConditions.push(mergeAndConditions(sqlConditions));
   }
 
   const promises = {};
 
   if (insertRows.length > 0) {
     const insertQuery = SQL`
       INSERT INTO updates(id, user, type, \`key\`,
         content, time, updater, target)
     `;
     insertQuery.append(SQL`VALUES ${insertRows}`);
     promises.insert = dbQuery(insertQuery);
   }
 
   if (publishInfos.size > 0) {
     promises.redis = redisPublish(publishInfos.values(), dontBroadcastSession);
   }
 
   if (deleteSQLConditions.length > 0) {
     promises.delete = (async () => {
       while (deleteSQLConditions.length > 0) {
         const batch = deleteSQLConditions.splice(0, deleteUpdatesBatchSize);
         await deleteUpdatesByConditions(batch);
       }
     })();
   }
 
   if (viewerRawUpdateInfos.length > 0) {
     invariant(viewerInfo, 'should be set');
     promises.updatesResult = fetchUpdateInfosWithRawUpdateInfos(
       viewerRawUpdateInfos,
       viewerInfo,
     );
   }
 
   const { updatesResult } = await promiseAll(promises);
   if (!updatesResult) {
     return defaultUpdateCreationResult;
   }
   const { updateInfos, userInfos } = updatesResult;
   return { viewerUpdates: updateInfos, userInfos };
 }
 
 export type FetchUpdatesResult = {
   +updateInfos: $ReadOnlyArray<ServerUpdateInfo>,
   +userInfos: UserInfos,
 };
 async function fetchUpdateInfosWithRawUpdateInfos(
   rawUpdateInfos: $ReadOnlyArray<RawUpdateInfo>,
   viewerInfo: ViewerInfo,
 ): Promise<FetchUpdatesResult> {
   const entitiesToFetch = rawUpdateInfos
     .map(info => updateSpecs[info.type].entitiesToFetch?.(info))
     .filter(Boolean);
   const currentUserNeedsFetch = entitiesToFetch.some(
     ({ currentUser }) => currentUser,
   );
   const threadIDsNeedingFetch = viewerInfo.threadInfos
     ? new Set()
     : new Set(entitiesToFetch.map(({ threadID }) => threadID).filter(Boolean));
   const entryIDsNeedingFetch = new Set(
     entitiesToFetch.map(({ entryID }) => entryID).filter(Boolean),
   );
   // entries and messages
   const threadIDsNeedingDetailedFetch = new Set(
     entitiesToFetch
       .map(({ detailedThreadID }) => detailedThreadID)
       .filter(Boolean),
   );
   const userIDsToFetch = new Set(
     entitiesToFetch.map(({ userID }) => userID).filter(Boolean),
   );
 
   const promises = {};
 
   const { viewer } = viewerInfo;
   if (!viewerInfo.threadInfos && threadIDsNeedingFetch.size > 0) {
     promises.threadResult = fetchThreadInfos(viewer, {
       threadIDs: threadIDsNeedingFetch,
     });
   }
 
   let calendarQuery: ?CalendarQuery = viewerInfo.calendarQuery
     ? viewerInfo.calendarQuery
     : null;
   if (!calendarQuery && viewer.hasSessionInfo) {
     // This should only ever happen for "legacy" clients who call in without
     // providing this information. These clients wouldn't know how to deal with
     // the corresponding UpdateInfos anyways, so no reason to be worried.
     calendarQuery = viewer.calendarQuery;
   } else if (!calendarQuery) {
     calendarQuery = defaultCalendarQuery(viewer.platform, viewer.timeZone);
   }
   if (threadIDsNeedingDetailedFetch.size > 0) {
     const threadCursors: { [string]: ?string } = {};
     for (const threadID of threadIDsNeedingDetailedFetch) {
       threadCursors[threadID] = null;
     }
     const messageSelectionCriteria: MessageSelectionCriteria = {
       threadCursors,
     };
     promises.messageInfosResult = fetchMessageInfos(
       viewer,
       messageSelectionCriteria,
       defaultNumberPerThread,
     );
     const threadCalendarQuery = {
       ...calendarQuery,
       filters: [
         ...nonThreadCalendarFilters(calendarQuery.filters),
         { type: 'threads', threadIDs: [...threadIDsNeedingDetailedFetch] },
       ],
     };
     promises.calendarResult = fetchEntryInfos(viewer, [threadCalendarQuery]);
   }
 
   if (entryIDsNeedingFetch.size > 0) {
     promises.entryInfosResult = fetchEntryInfosByID(
       viewer,
       entryIDsNeedingFetch,
     );
   }
 
   if (currentUserNeedsFetch) {
     promises.currentUserInfoResult = (async () => {
       const currentUserInfo = await fetchCurrentUserInfo(viewer);
       invariant(currentUserInfo.anonymous === undefined, 'should be logged in');
       return currentUserInfo;
     })();
   }
 
   if (userIDsToFetch.size > 0) {
     promises.userInfosResult = fetchKnownUserInfos(viewer, [...userIDsToFetch]);
   }
 
   const {
     threadResult,
     messageInfosResult,
     calendarResult,
     entryInfosResult,
     currentUserInfoResult,
     userInfosResult,
   } = await promiseAll(promises);
 
   let threadInfos = {};
   if (viewerInfo.threadInfos) {
     threadInfos = viewerInfo.threadInfos;
   } else if (threadResult) {
     threadInfos = threadResult.threadInfos;
   }
 
   return await updateInfosFromRawUpdateInfos(viewer, rawUpdateInfos, {
     threadInfos,
     messageInfosResult,
     calendarResult,
     entryInfosResult,
     currentUserInfoResult,
     userInfosResult,
   });
 }
 
 async function updateInfosFromRawUpdateInfos(
   viewer: Viewer,
   rawUpdateInfos: $ReadOnlyArray<RawUpdateInfo>,
   rawData: UpdateInfosRawData,
 ): Promise<FetchUpdatesResult> {
   const { messageInfosResult, calendarResult, userInfosResult } = rawData;
 
   const rawEntryInfosByThreadID = {};
   for (const entryInfo of calendarResult?.rawEntryInfos ?? []) {
     if (!rawEntryInfosByThreadID[entryInfo.threadID]) {
       rawEntryInfosByThreadID[entryInfo.threadID] = [];
     }
     rawEntryInfosByThreadID[entryInfo.threadID].push(entryInfo);
   }
 
   const rawMessageInfosByThreadID = {};
   for (const messageInfo of messageInfosResult?.rawMessageInfos ?? []) {
     if (!rawMessageInfosByThreadID[messageInfo.threadID]) {
       rawMessageInfosByThreadID[messageInfo.threadID] = [];
     }
     rawMessageInfosByThreadID[messageInfo.threadID].push(messageInfo);
   }
 
   const params = {
     data: rawData,
     rawEntryInfosByThreadID,
     rawMessageInfosByThreadID,
   };
   const updateInfos = rawUpdateInfos
     .map(update =>
       updateSpecs[update.type].updateInfoFromRawInfo(update, params),
     )
     .filter(Boolean);
 
   updateInfos.sort(sortFunction);
 
   // Now we'll attempt to merge UpdateInfos so that we only have one per key
   const updateForKey: Map<string, ServerUpdateInfo> = new Map();
   const mergedUpdates: ServerUpdateInfo[] = [];
   for (const updateInfo of updateInfos) {
     const key = keyForUpdateInfo(updateInfo);
     if (!key) {
       mergedUpdates.push(updateInfo);
       continue;
-    } else if (
-      updateInfo.type === updateTypes.DELETE_THREAD ||
-      updateInfo.type === updateTypes.JOIN_THREAD ||
-      updateInfo.type === updateTypes.DELETE_ACCOUNT
-    ) {
-      updateForKey.set(key, updateInfo);
-      continue;
     }
     const currentUpdateInfo = updateForKey.get(key);
-    if (!currentUpdateInfo) {
-      updateForKey.set(key, updateInfo);
-    } else if (
-      updateInfo.type === updateTypes.UPDATE_THREAD &&
-      currentUpdateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS
+    if (
+      !currentUpdateInfo ||
+      updateInfo.type === updateTypes.DELETE_THREAD ||
+      updateInfo.type === updateTypes.JOIN_THREAD ||
+      updateInfo.type === updateTypes.DELETE_ACCOUNT ||
+      updateInfo.type === updateTypes.UPDATE_ENTRY ||
+      updateInfo.type === updateTypes.UPDATE_CURRENT_USER
     ) {
-      // UPDATE_THREAD trumps UPDATE_THREAD_READ_STATUS
-      // Note that we keep the oldest UPDATE_THREAD
       updateForKey.set(key, updateInfo);
     } else if (
-      updateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS &&
-      currentUpdateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS
+      (updateInfo.type === updateTypes.UPDATE_THREAD &&
+        currentUpdateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS) ||
+      (updateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS &&
+        currentUpdateInfo.type === updateTypes.UPDATE_THREAD_READ_STATUS)
     ) {
-      // If we only have UPDATE_THREAD_READ_STATUS, keep the most recent
-      updateForKey.set(key, updateInfo);
-    } else if (updateInfo.type === updateTypes.UPDATE_ENTRY) {
-      updateForKey.set(key, updateInfo);
-    } else if (updateInfo.type === updateTypes.UPDATE_CURRENT_USER) {
       updateForKey.set(key, updateInfo);
     }
   }
   for (const [, updateInfo] of updateForKey) {
     mergedUpdates.push(updateInfo);
   }
   mergedUpdates.sort(sortFunction);
 
   return { updateInfos: mergedUpdates, userInfos: userInfosResult ?? {} };
 }
 
 type PublishInfo = {
   updateTarget: UpdateTarget,
   rawUpdateInfos: RawUpdateInfo[],
 };
 async function redisPublish(
   publishInfos: Iterator<PublishInfo>,
   dontBroadcastSession: ?string,
 ): Promise<void> {
   for (const publishInfo of publishInfos) {
     const { updateTarget, rawUpdateInfos } = publishInfo;
     const redisMessage: NewUpdatesRedisMessage = {
       type: redisMessageTypes.NEW_UPDATES,
       updates: rawUpdateInfos,
     };
     if (!updateTarget.sessionID && dontBroadcastSession) {
       redisMessage.ignoreSession = dontBroadcastSession;
     }
     publisher.sendMessage(updateTarget, redisMessage);
   }
 }
 
 function getTargetFromUpdateData(updateData: UpdateData): ?string {
   if (updateData.targetSession) {
     return updateData.targetSession;
   } else if (updateData.targetCookie) {
     return updateData.targetCookie;
   } else {
     return null;
   }
 }
 
 function getDeleteCondition(updateData: UpdateData): ?DeleteCondition {
   const types = updateSpecs[updateData.type].deleteCondition;
   if (!types) {
     return null;
   }
 
   const target = getTargetFromUpdateData(updateData);
   const { userID } = updateData;
   return { userID, target, types };
 }
 
 function filterOnDeleteCondition(
   updateData: UpdateData,
   deleteCondition: DeleteCondition,
 ): boolean {
   invariant(
     updateData.userID === deleteCondition.userID,
     `updateData of type ${updateData.type} being compared to wrong userID`,
   );
   if (deleteCondition.target) {
     const target = getTargetFromUpdateData(updateData);
     if (target !== deleteCondition.target) {
       return true;
     }
   }
   if (deleteCondition.types === 'all_types') {
     return false;
   }
   return !deleteCondition.types.has(updateData.type);
 }
 
 export { createUpdates, fetchUpdateInfosWithRawUpdateInfos };