diff --git a/lib/shared/dm-ops/add-members-spec.js b/lib/shared/dm-ops/add-members-spec.js
--- a/lib/shared/dm-ops/add-members-spec.js
+++ b/lib/shared/dm-ops/add-members-spec.js
@@ -57,7 +57,7 @@
 
   const { parentThreadID } = threadInfo;
   const parentThreadInfo = parentThreadID
-    ? utilities.threadInfos[parentThreadID]
+    ? utilities.rawThreadInfos[parentThreadID]
     : null;
   if (parentThreadID && !parentThreadInfo) {
     console.log(
@@ -85,7 +85,7 @@
     utilities: ProcessDMOperationUtilities,
   ) => {
     const { editorID, time, addedUserIDs, threadID } = dmOperation;
-    const { viewerID, threadInfos } = utilities;
+    const { viewerID, rawThreadInfos } = utilities;
 
     const messageDataWithMessageInfos =
       createAddNewMembersMessageDataWithInfoFromDMOperation(dmOperation);
@@ -93,7 +93,7 @@
     const { rawMessageInfo } = messageDataWithMessageInfos;
     const rawMessageInfos = [rawMessageInfo];
 
-    const currentThreadInfo = threadInfos[threadID];
+    const currentThreadInfo = rawThreadInfos[threadID];
 
     const { membershipPermissions, roleID } = createPermissionsForNewMembers(
       currentThreadInfo,
@@ -169,7 +169,7 @@
     dmOperation: DMAddMembersOperation,
     utilities: ProcessDMOperationUtilities,
   ) => {
-    if (utilities.threadInfos[dmOperation.threadID]) {
+    if (utilities.rawThreadInfos[dmOperation.threadID]) {
       return { isProcessingPossible: true };
     }
     return {
diff --git a/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js b/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
--- a/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
+++ b/lib/shared/dm-ops/add-viewer-to-thread-members-spec.js
@@ -53,7 +53,7 @@
     ) => {
       const { time, messageID, addedUserIDs, existingThreadDetails, editorID } =
         dmOperation;
-      const { threadInfos } = utilities;
+      const { rawThreadInfos } = utilities;
 
       let rawMessageInfos: Array<RawMessageInfo> = [];
       let messageDataWithMessageInfos: ?{
@@ -70,7 +70,7 @@
       }
 
       const threadID = existingThreadDetails.threadID;
-      const currentThreadInfo = threadInfos[threadID];
+      const currentThreadInfo = rawThreadInfos[threadID];
 
       const memberTimestamps = {
         ...currentThreadInfo?.timestamps?.members,
diff --git a/lib/shared/dm-ops/change-thread-read-status-spec.js b/lib/shared/dm-ops/change-thread-read-status-spec.js
--- a/lib/shared/dm-ops/change-thread-read-status-spec.js
+++ b/lib/shared/dm-ops/change-thread-read-status-spec.js
@@ -27,7 +27,7 @@
         notificationsCreationData = { rescindData: { threadID } };
       }
 
-      const threadInfo = utilities.threadInfos[threadID];
+      const threadInfo = utilities.rawThreadInfos[threadID];
       if (threadInfo.timestamps.currentUser.unread > time) {
         return {
           rawMessageInfos: [],
@@ -58,12 +58,12 @@
       utilities: ProcessDMOperationUtilities,
     ) => {
       const { creatorID, threadID } = dmOperation;
-      const { threadInfos, viewerID } = utilities;
+      const { rawThreadInfos, viewerID } = utilities;
       if (viewerID !== creatorID) {
         return { isProcessingPossible: false, reason: { type: 'invalid' } };
       }
 
-      if (!threadInfos[threadID]) {
+      if (!rawThreadInfos[threadID]) {
         return {
           isProcessingPossible: false,
           reason: { type: 'missing_thread', threadID },
diff --git a/lib/shared/dm-ops/change-thread-settings-spec.js b/lib/shared/dm-ops/change-thread-settings-spec.js
--- a/lib/shared/dm-ops/change-thread-settings-spec.js
+++ b/lib/shared/dm-ops/change-thread-settings-spec.js
@@ -141,7 +141,7 @@
       const { time } = dmOperation;
       const threadID = getThreadIDFromChangeThreadSettingsDMOp(dmOperation);
 
-      const threadInfo = utilities.threadInfos[threadID];
+      const threadInfo = utilities.rawThreadInfos[threadID];
       const updateInfos: Array<ClientUpdateInfo> = [];
 
       const { fieldNameToMessageData, threadInfoUpdate } =
@@ -197,7 +197,7 @@
       dmOperation: DMChangeThreadSettingsOperation,
       utilities: ProcessDMOperationUtilities,
     ) => {
-      if (!utilities.threadInfos[dmOperation.threadID]) {
+      if (!utilities.rawThreadInfos[dmOperation.threadID]) {
         return {
           isProcessingPossible: false,
           reason: {
diff --git a/lib/shared/dm-ops/change-thread-subscription.js b/lib/shared/dm-ops/change-thread-subscription.js
--- a/lib/shared/dm-ops/change-thread-subscription.js
+++ b/lib/shared/dm-ops/change-thread-subscription.js
@@ -21,9 +21,9 @@
       utilities: ProcessDMOperationUtilities,
     ) => {
       const { creatorID, threadID, subscription, time } = dmOperation;
-      const { viewerID, threadInfos } = utilities;
+      const { viewerID, rawThreadInfos } = utilities;
 
-      const threadInfo = threadInfos[threadID];
+      const threadInfo = rawThreadInfos[threadID];
 
       if (threadInfo.timestamps.members[creatorID].subscription > time) {
         return {
@@ -91,7 +91,7 @@
       utilities: ProcessDMOperationUtilities,
     ) => {
       const { threadID, creatorID } = dmOperation;
-      if (!utilities.threadInfos[threadID]) {
+      if (!utilities.rawThreadInfos[threadID]) {
         return {
           isProcessingPossible: false,
           reason: { type: 'missing_thread', threadID },
@@ -99,7 +99,7 @@
       }
 
       if (
-        !utilities.threadInfos[threadID].members.find(
+        !utilities.rawThreadInfos[threadID].members.find(
           memberInfo => memberInfo.id === creatorID,
         )
       ) {
diff --git a/lib/shared/dm-ops/create-entry-spec.js b/lib/shared/dm-ops/create-entry-spec.js
--- a/lib/shared/dm-ops/create-entry-spec.js
+++ b/lib/shared/dm-ops/create-entry-spec.js
@@ -72,7 +72,7 @@
     const notificationsCreationData = {
       messageDatasWithMessageInfos: [messageDataWithMessageInfos],
       thickRawThreadInfos: {
-        [threadID]: utilities.threadInfos[threadID],
+        [threadID]: utilities.rawThreadInfos[threadID],
       },
     };
 
@@ -99,7 +99,7 @@
         },
       };
     }
-    if (utilities.threadInfos[dmOperation.threadID]) {
+    if (utilities.rawThreadInfos[dmOperation.threadID]) {
       return { isProcessingPossible: true };
     }
     return {
diff --git a/lib/shared/dm-ops/create-sidebar-spec.js b/lib/shared/dm-ops/create-sidebar-spec.js
--- a/lib/shared/dm-ops/create-sidebar-spec.js
+++ b/lib/shared/dm-ops/create-sidebar-spec.js
@@ -13,22 +13,29 @@
 } from '../../types/dm-ops.js';
 import { messageTypes } from '../../types/message-types-enum.js';
 import {
-  type RawMessageInfo,
   messageTruncationStatus,
+  type RawMessageInfo,
+  type ValidRawSidebarSourceMessageInfo,
 } from '../../types/message-types.js';
 import { joinThreadSubscription } from '../../types/subscription-types.js';
 import { threadTypes } from '../../types/thread-types-enum.js';
 import { updateTypes } from '../../types/update-types-enum.js';
 import { generatePendingThreadColor } from '../color-utils.js';
 import {
+  createMessageInfo,
   isValidRawSidebarSourceMessageInfo,
   rawMessageInfoFromMessageData,
 } from '../message-utils.js';
+import {
+  createSidebarThreadName,
+  createSidebarTitle,
+} from '../sidebar-utils.js';
 import { createThreadTimestamps } from '../thread-utils.js';
 
-async function createMessageDatasWithInfosFromDMOperation(
+function createMessageDatasWithInfosFromDMOperation(
   dmOperation: DMCreateSidebarOperation,
   utilities: ProcessDMOperationUtilities,
+  sourceMessage: ValidRawSidebarSourceMessageInfo,
   threadColor?: string,
 ) {
   const {
@@ -37,26 +44,12 @@
     time,
     parentThreadID,
     memberIDs,
-    sourceMessageID,
     newSidebarSourceMessageID,
     newCreateSidebarMessageID,
   } = dmOperation;
 
   const allMemberIDs = [creatorID, ...memberIDs];
   const color = threadColor ?? generatePendingThreadColor(allMemberIDs);
-  const sourceMessage = await utilities.fetchMessage(sourceMessageID);
-
-  if (!sourceMessage) {
-    throw new Error(
-      `could not find sourceMessage ${sourceMessageID}... probably ` +
-        'joined thick thread ${parentThreadID} after its creation',
-    );
-  }
-  if (!isValidRawSidebarSourceMessageInfo(sourceMessage)) {
-    throw new Error(
-      `sourceMessage ${sourceMessageID} is an invalid sidebar source`,
-    );
-  }
 
   const sidebarSourceMessageData = {
     type: messageTypes.SIDEBAR_SOURCE,
@@ -117,6 +110,40 @@
         subscription: joinThreadSubscription,
       }));
 
+      const sourceMessage = await utilities.fetchMessage(sourceMessageID);
+      if (!sourceMessage) {
+        throw new Error(
+          `could not find sourceMessage ${sourceMessageID}... probably ` +
+            'joined thick thread ${parentThreadID} after its creation',
+        );
+      }
+      if (!isValidRawSidebarSourceMessageInfo(sourceMessage)) {
+        throw new Error(
+          `sourceMessage ${sourceMessageID} is an invalid sidebar source`,
+        );
+      }
+
+      const sourceMessageInfo = createMessageInfo(
+        sourceMessage,
+        viewerID,
+        utilities.userInfos,
+        utilities.threadInfos,
+      );
+      const parentThreadInfo = utilities.threadInfos[parentThreadID];
+      let messageTitle = null;
+      if (sourceMessageInfo && parentThreadInfo) {
+        messageTitle = await createSidebarTitle(
+          sourceMessageInfo,
+          parentThreadInfo,
+          utilities.markdownRules,
+          utilities.getENSNames,
+          utilities.getFCNames,
+        );
+      }
+      const threadName = messageTitle
+        ? createSidebarThreadName(messageTitle)
+        : null;
+
       const rawThreadInfo = createThickRawThreadInfo(
         {
           threadID,
@@ -126,6 +153,7 @@
           allMemberIDsWithSubscriptions,
           roleID,
           unread: creatorID !== viewerID,
+          name: threadName,
           sourceMessageID,
           containingThreadID: parentThreadID,
           timestamps: createThreadTimestamps(time, allMemberIDs),
@@ -138,9 +166,10 @@
         createSidebarMessageData,
         createSidebarMessageInfo,
         sidebarSourceMessageInfo,
-      } = await createMessageDatasWithInfosFromDMOperation(
+      } = createMessageDatasWithInfosFromDMOperation(
         dmOperation,
         utilities,
+        sourceMessage,
         rawThreadInfo.color,
       );
 
@@ -172,7 +201,7 @@
         ],
         thickRawThreadInfos: {
           [threadID]: rawThreadInfo,
-          [parentThreadID]: utilities.threadInfos[parentThreadID],
+          [parentThreadID]: utilities.rawThreadInfos[parentThreadID],
         },
       };
 
@@ -187,7 +216,7 @@
       dmOperation: DMCreateSidebarOperation,
       utilities: ProcessDMOperationUtilities,
     ) => {
-      if (utilities.threadInfos[dmOperation.threadID]) {
+      if (utilities.rawThreadInfos[dmOperation.threadID]) {
         console.log(
           'Discarded a CREATE_SIDEBAR operation because thread ' +
             `with the same ID ${dmOperation.threadID} already exists ` +
diff --git a/lib/shared/dm-ops/create-thread-spec.js b/lib/shared/dm-ops/create-thread-spec.js
--- a/lib/shared/dm-ops/create-thread-spec.js
+++ b/lib/shared/dm-ops/create-thread-spec.js
@@ -130,7 +130,7 @@
   const threadColor = color ?? generatePendingThreadColor(memberIDs);
 
   const parentThreadInfo = parentThreadID
-    ? utilities.threadInfos[parentThreadID]
+    ? utilities.rawThreadInfos[parentThreadID]
     : null;
   if (parentThreadID && !parentThreadInfo) {
     console.log(
@@ -290,7 +290,7 @@
       dmOperation: DMCreateThreadOperation,
       utilities: ProcessDMOperationUtilities,
     ) => {
-      if (utilities.threadInfos[dmOperation.threadID]) {
+      if (utilities.rawThreadInfos[dmOperation.threadID]) {
         console.log(
           'Discarded a CREATE_THREAD operation because thread ' +
             `with the same ID ${dmOperation.threadID} already exists ` +
diff --git a/lib/shared/dm-ops/delete-entry-spec.js b/lib/shared/dm-ops/delete-entry-spec.js
--- a/lib/shared/dm-ops/delete-entry-spec.js
+++ b/lib/shared/dm-ops/delete-entry-spec.js
@@ -65,7 +65,7 @@
     const notificationsCreationData = {
       messageDatasWithMessageInfos: [messageDataWithMessageInfos],
       thickRawThreadInfos: {
-        [threadID]: utilities.threadInfos[threadID],
+        [threadID]: utilities.rawThreadInfos[threadID],
       },
     };
 
diff --git a/lib/shared/dm-ops/dm-op-spec.js b/lib/shared/dm-ops/dm-op-spec.js
--- a/lib/shared/dm-ops/dm-op-spec.js
+++ b/lib/shared/dm-ops/dm-op-spec.js
@@ -6,16 +6,26 @@
 import type { RawEntryInfos } from '../../types/entry-types.js';
 import type { UserIdentitiesResponse } from '../../types/identity-service-types.js';
 import type { RawMessageInfo } from '../../types/message-types.js';
+import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { ThickRawThreadInfos } from '../../types/thread-types.js';
+import type { UserInfos } from '../../types/user-types.js';
+import type { GetENSNames } from '../../utils/ens-helpers.js';
+import type { GetFCNames } from '../../utils/farcaster-helpers.js';
+import type { ParserRules } from '../markdown.js';
 
 export type ProcessDMOperationUtilities = {
   +viewerID: string,
   +fetchMessage: (messageID: string) => Promise<?RawMessageInfo>,
-  +threadInfos: ThickRawThreadInfos,
+  +rawThreadInfos: ThickRawThreadInfos,
+  +threadInfos: { +[id: string]: ThreadInfo },
   +entryInfos: RawEntryInfos,
   +findUserIdentities: (
     userIDs: $ReadOnlyArray<string>,
   ) => Promise<UserIdentitiesResponse>,
+  +userInfos: UserInfos,
+  +getENSNames: ?GetENSNames,
+  +getFCNames: ?GetFCNames,
+  +markdownRules: ParserRules,
 };
 
 export type ProcessingPossibilityCheckResult =
diff --git a/lib/shared/dm-ops/dm-op-utils.js b/lib/shared/dm-ops/dm-op-utils.js
--- a/lib/shared/dm-ops/dm-op-utils.js
+++ b/lib/shared/dm-ops/dm-op-utils.js
@@ -18,11 +18,16 @@
   removePeerUsersActionType,
 } from '../../actions/aux-user-actions.js';
 import { useFindUserIdentities } from '../../actions/find-user-identities-actions.js';
+import { ENSCacheContext } from '../../components/ens-cache-provider.react.js';
+import { NeynarClientContext } from '../../components/neynar-client-provider.react.js';
 import { useLoggedInUserInfo } from '../../hooks/account-hooks.js';
 import { useGetLatestMessageEdit } from '../../hooks/latest-message-edit.js';
 import { useGetAndUpdateDeviceListsForUsers } from '../../hooks/peer-list-hooks.js';
 import { mergeUpdatesWithMessageInfos } from '../../reducers/message-reducer.js';
-import { thickRawThreadInfosSelector } from '../../selectors/thread-selectors.js';
+import {
+  thickRawThreadInfosSelector,
+  threadInfoSelector,
+} from '../../selectors/thread-selectors.js';
 import { getAllPeerUserIDAndDeviceIDs } from '../../selectors/user-selectors.js';
 import { type P2PMessageRecipient } from '../../tunnelbroker/peer-to-peer-context.js';
 import type {
@@ -47,6 +52,7 @@
   AccountDeletionUpdateInfo,
   ClientUpdateInfo,
 } from '../../types/update-types.js';
+import { getConfig } from '../../utils/config.js';
 import { getContentSigningKey } from '../../utils/crypto-utils.js';
 import { useSelector, useDispatch } from '../../utils/redux-utils.js';
 import {
@@ -200,7 +206,7 @@
       operation: DMOperation,
       recipients: OutboundDMOperationSpecificationRecipients,
     ): Promise<$ReadOnlyArray<OutboundP2PMessage>> => {
-      const { viewerID, threadInfos } = utilities;
+      const { viewerID, rawThreadInfos } = utilities;
       if (!viewerID) {
         return [];
       }
@@ -220,14 +226,14 @@
         );
       } else if (recipients.type === 'all_thread_members') {
         const { threadID } = recipients;
-        if (!threadInfos[threadID]) {
+        if (!rawThreadInfos[threadID]) {
           console.log(
             `all_thread_members called for threadID ${threadID}, which is ` +
               'missing from the ThreadStore. if sending a message soon after ' +
               'thread creation, consider some_users instead',
           );
         }
-        const members = threadInfos[recipients.threadID]?.members ?? [];
+        const members = rawThreadInfos[recipients.threadID]?.members ?? [];
         const memberIDs = members.map(member => member.id);
 
         const missingPeers = await getMissingPeers(memberIDs);
@@ -431,20 +437,50 @@
   viewerID: ?string,
 }> {
   const fetchMessage = useGetLatestMessageEdit();
-  const threadInfos = useSelector(thickRawThreadInfosSelector);
+  const rawThreadInfos = useSelector(thickRawThreadInfosSelector);
+  const threadInfos = useSelector(threadInfoSelector);
   const entryInfos = useSelector(state => state.entryStore.entryInfos);
+  const userInfos = useSelector(state => state.userStore.userInfos);
   const findUserIdentities = useFindUserIdentities();
   const loggedInUserInfo = useLoggedInUserInfo();
   const viewerID = loggedInUserInfo?.id;
+
+  const ensCache = React.useContext(ENSCacheContext);
+  const getENSNames = ensCache?.getENSNames;
+
+  const neynarClientContext = React.useContext(NeynarClientContext);
+  const getFCNames = neynarClientContext?.getFCNames;
+
+  const markdownRules = React.useMemo(
+    () => getConfig().getDefaultTextMessageRules({}).simpleMarkdownRules,
+    [],
+  );
+
   return React.useMemo(
     () => ({
       viewerID,
       fetchMessage,
+      rawThreadInfos,
       threadInfos,
       entryInfos,
+      userInfos,
       findUserIdentities,
+      getENSNames,
+      getFCNames,
+      markdownRules,
     }),
-    [viewerID, fetchMessage, threadInfos, entryInfos, findUserIdentities],
+    [
+      viewerID,
+      fetchMessage,
+      rawThreadInfos,
+      threadInfos,
+      entryInfos,
+      userInfos,
+      findUserIdentities,
+      getENSNames,
+      getFCNames,
+      markdownRules,
+    ],
   );
 }
 
diff --git a/lib/shared/dm-ops/edit-entry-spec.js b/lib/shared/dm-ops/edit-entry-spec.js
--- a/lib/shared/dm-ops/edit-entry-spec.js
+++ b/lib/shared/dm-ops/edit-entry-spec.js
@@ -66,7 +66,7 @@
     const notificationsCreationData = {
       messageDatasWithMessageInfos: [messageDataWithMessageInfos],
       thickRawThreadInfos: {
-        [threadID]: utilities.threadInfos[threadID],
+        [threadID]: utilities.rawThreadInfos[threadID],
       },
     };
 
diff --git a/lib/shared/dm-ops/join-thread-spec.js b/lib/shared/dm-ops/join-thread-spec.js
--- a/lib/shared/dm-ops/join-thread-spec.js
+++ b/lib/shared/dm-ops/join-thread-spec.js
@@ -49,8 +49,8 @@
     utilities: ProcessDMOperationUtilities,
   ) => {
     const { joinerID, time, existingThreadDetails } = dmOperation;
-    const { viewerID, threadInfos } = utilities;
-    const currentThreadInfo = threadInfos[existingThreadDetails.threadID];
+    const { viewerID, rawThreadInfos } = utilities;
+    const currentThreadInfo = rawThreadInfos[existingThreadDetails.threadID];
 
     const messageDataWithMessageInfos =
       createMessageDataWithInfoFromDMOperation(dmOperation);
@@ -137,7 +137,7 @@
 
       const parentThreadID = existingThreadDetails.parentThreadID;
       const parentThreadInfo = parentThreadID
-        ? utilities.threadInfos[parentThreadID]
+        ? utilities.rawThreadInfos[parentThreadID]
         : null;
       if (parentThreadID && !parentThreadInfo) {
         console.log(
@@ -194,9 +194,9 @@
     dmOperation: DMJoinThreadOperation,
     utilities: ProcessDMOperationUtilities,
   ) => {
-    const { viewerID, threadInfos } = utilities;
+    const { viewerID, rawThreadInfos } = utilities;
     if (
-      threadInfos[dmOperation.existingThreadDetails.threadID] ||
+      rawThreadInfos[dmOperation.existingThreadDetails.threadID] ||
       dmOperation.joinerID === viewerID
     ) {
       return { isProcessingPossible: true };
diff --git a/lib/shared/dm-ops/leave-thread-spec.js b/lib/shared/dm-ops/leave-thread-spec.js
--- a/lib/shared/dm-ops/leave-thread-spec.js
+++ b/lib/shared/dm-ops/leave-thread-spec.js
@@ -113,8 +113,8 @@
     utilities: ProcessDMOperationUtilities,
   ) => {
     const { editorID, time, threadID } = dmOperation;
-    const { viewerID, threadInfos } = utilities;
-    const threadInfo = threadInfos[threadID];
+    const { viewerID, rawThreadInfos } = utilities;
+    const threadInfo = rawThreadInfos[threadID];
 
     const messageDataWithMessageInfos =
       createMessageDataWithInfoFromDMOperation(dmOperation);
@@ -163,7 +163,7 @@
             ...createDeleteSubthreadsUpdates(
               dmOperation,
               threadInfo,
-              threadInfos,
+              rawThreadInfos,
             ),
           ],
           blobOps: [],
@@ -173,7 +173,7 @@
 
       const parentThreadID = threadInfo.parentThreadID;
       const parentThreadInfo = parentThreadID
-        ? utilities.threadInfos[parentThreadID]
+        ? utilities.rawThreadInfos[parentThreadID]
         : null;
       if (parentThreadID && !parentThreadInfo) {
         console.log(
@@ -223,7 +223,7 @@
     const updateInfos = createLeaveSubthreadsUpdates(
       dmOperation,
       threadInfo,
-      threadInfos,
+      rawThreadInfos,
     );
 
     // It is possible that the editor has joined this thread after leaving it,
@@ -264,7 +264,7 @@
     dmOperation: DMLeaveThreadOperation,
     utilities: ProcessDMOperationUtilities,
   ) => {
-    if (utilities.threadInfos[dmOperation.threadID]) {
+    if (utilities.rawThreadInfos[dmOperation.threadID]) {
       return { isProcessingPossible: true };
     }
     return {
diff --git a/lib/shared/dm-ops/send-edit-message-spec.js b/lib/shared/dm-ops/send-edit-message-spec.js
--- a/lib/shared/dm-ops/send-edit-message-spec.js
+++ b/lib/shared/dm-ops/send-edit-message-spec.js
@@ -42,7 +42,8 @@
       const notificationsCreationData = {
         messageDatasWithMessageInfos: [messageDataWithMessageInfos],
         thickRawThreadInfos: {
-          [dmOperation.threadID]: utilities.threadInfos[dmOperation.threadID],
+          [dmOperation.threadID]:
+            utilities.rawThreadInfos[dmOperation.threadID],
         },
       };
 
diff --git a/lib/shared/dm-ops/send-multimedia-message-spec.js b/lib/shared/dm-ops/send-multimedia-message-spec.js
--- a/lib/shared/dm-ops/send-multimedia-message-spec.js
+++ b/lib/shared/dm-ops/send-multimedia-message-spec.js
@@ -77,7 +77,8 @@
       const notificationsCreationData = {
         messageDatasWithMessageInfos: [messageDataWithMessageInfos],
         thickRawThreadInfos: {
-          [dmOperation.threadID]: utilities.threadInfos[dmOperation.threadID],
+          [dmOperation.threadID]:
+            utilities.rawThreadInfos[dmOperation.threadID],
         },
       };
 
@@ -92,7 +93,7 @@
       dmOperation: DMSendMultimediaMessageOperation,
       utilities: ProcessDMOperationUtilities,
     ) => {
-      if (!utilities.threadInfos[dmOperation.threadID]) {
+      if (!utilities.rawThreadInfos[dmOperation.threadID]) {
         return {
           isProcessingPossible: false,
           reason: {
diff --git a/lib/shared/dm-ops/send-reaction-message-spec.js b/lib/shared/dm-ops/send-reaction-message-spec.js
--- a/lib/shared/dm-ops/send-reaction-message-spec.js
+++ b/lib/shared/dm-ops/send-reaction-message-spec.js
@@ -50,7 +50,8 @@
       const notificationsCreationData = {
         messageDatasWithMessageInfos: [messageDataWithMessageInfos],
         thickRawThreadInfos: {
-          [dmOperation.threadID]: utilities.threadInfos[dmOperation.threadID],
+          [dmOperation.threadID]:
+            utilities.rawThreadInfos[dmOperation.threadID],
         },
       };
 
diff --git a/lib/shared/dm-ops/send-text-message-spec.js b/lib/shared/dm-ops/send-text-message-spec.js
--- a/lib/shared/dm-ops/send-text-message-spec.js
+++ b/lib/shared/dm-ops/send-text-message-spec.js
@@ -42,7 +42,8 @@
       const notificationsCreationData = {
         messageDatasWithMessageInfos: [messageDataWithMessageInfos],
         thickRawThreadInfos: {
-          [dmOperation.threadID]: utilities.threadInfos[dmOperation.threadID],
+          [dmOperation.threadID]:
+            utilities.rawThreadInfos[dmOperation.threadID],
         },
       };
 
@@ -57,7 +58,7 @@
       dmOperation: DMSendTextMessageOperation,
       utilities: ProcessDMOperationUtilities,
     ) => {
-      if (!utilities.threadInfos[dmOperation.threadID]) {
+      if (!utilities.rawThreadInfos[dmOperation.threadID]) {
         return {
           isProcessingPossible: false,
           reason: {
diff --git a/lib/shared/dm-ops/update-relationship-spec.js b/lib/shared/dm-ops/update-relationship-spec.js
--- a/lib/shared/dm-ops/update-relationship-spec.js
+++ b/lib/shared/dm-ops/update-relationship-spec.js
@@ -74,7 +74,8 @@
       const notificationsCreationData = {
         messageDatasWithMessageInfos: [messageDataWithMessageInfos],
         thickRawThreadInfos: {
-          [dmOperation.threadID]: utilities.threadInfos[dmOperation.threadID],
+          [dmOperation.threadID]:
+            utilities.rawThreadInfos[dmOperation.threadID],
         },
       };
 
diff --git a/lib/shared/message-utils.js b/lib/shared/message-utils.js
--- a/lib/shared/message-utils.js
+++ b/lib/shared/message-utils.js
@@ -30,7 +30,6 @@
 import type { Media } from '../types/media-types.js';
 import { messageTypes } from '../types/message-types-enum.js';
 import {
-  type ComposableMessageInfo,
   type FetchMessageInfosPayload,
   type MessageData,
   type MessageInfo,
@@ -43,12 +42,8 @@
   type ValidRawSidebarSourceMessageInfo,
   type ValidSidebarSourceMessageInfo,
 } from '../types/message-types.js';
-import type { CompoundReactionMessageInfo } from '../types/messages/compound-reaction.js';
-import type { DeleteMessageInfo } from '../types/messages/delete.js';
-import type { EditMessageInfo } from '../types/messages/edit.js';
 import type { ImagesMessageData } from '../types/messages/images.js';
 import type { MediaMessageData } from '../types/messages/media.js';
-import type { ReactionMessageInfo } from '../types/messages/reaction.js';
 import type {
   RawThreadInfo,
   ThreadInfo,
@@ -254,13 +249,7 @@
 }
 
 function getMessageTitle(
-  messageInfo:
-    | ComposableMessageInfo
-    | RobotextMessageInfo
-    | ReactionMessageInfo
-    | EditMessageInfo
-    | DeleteMessageInfo
-    | CompoundReactionMessageInfo,
+  messageInfo: MessageInfo,
   threadInfo: ThreadInfo,
   parentThreadInfo: ?ThreadInfo,
   markdownRules: ParserRules,
@@ -277,7 +266,8 @@
       messageInfo.type !== messageTypes.REACTION &&
       messageInfo.type !== messageTypes.EDIT_MESSAGE &&
       messageInfo.type !== messageTypes.DELETE_MESSAGE &&
-      messageInfo.type !== messageTypes.COMPOUND_REACTION,
+      messageInfo.type !== messageTypes.COMPOUND_REACTION &&
+      messageInfo.type !== messageTypes.SIDEBAR_SOURCE,
     'messageTitle can only be auto-generated for RobotextMessageInfo',
   );
   return robotextForMessageInfo(messageInfo, threadInfo, parentThreadInfo);
diff --git a/lib/shared/sidebar-utils.js b/lib/shared/sidebar-utils.js
--- a/lib/shared/sidebar-utils.js
+++ b/lib/shared/sidebar-utils.js
@@ -7,18 +7,19 @@
 import { relationshipBlockedInEitherDirection } from './relationship-utils.js';
 import {
   createPendingThread,
-  getSingleOtherUser,
   extractMentionedMembers,
-  useThreadHasPermission,
+  getSingleOtherUser,
   userIsMember,
+  useThreadHasPermission,
 } from './thread-utils.js';
 import { threadSpecs, threadTypeIsPersonal } from './threads/thread-specs.js';
 import type { ChatMessageInfoItem } from '../selectors/chat-selectors.js';
 import { chatMessageItemEngagementTargetMessageInfo } from '../shared/chat-message-item-utils.js';
 import { messageTypes } from '../types/message-types-enum.js';
 import type {
-  RobotextMessageInfo,
   ComposableMessageInfo,
+  MessageInfo,
+  RobotextMessageInfo,
 } from '../types/message-types.js';
 import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from '../types/thread-permission-types.js';
@@ -159,6 +160,26 @@
   +getFCNames: ?GetFCNames,
 };
 
+async function createSidebarTitle(
+  sourceMessageInfo: MessageInfo,
+  parentThreadInfo: ThreadInfo,
+  markdownRules: ParserRules,
+  getENSNames: ?GetENSNames,
+  getFCNames: ?GetFCNames,
+): Promise<?string> {
+  const messageTitleEntityText = getMessageTitle(
+    sourceMessageInfo,
+    parentThreadInfo,
+    parentThreadInfo,
+    markdownRules,
+  );
+  return await getEntityTextAsString(
+    messageTitleEntityText,
+    { getENSNames, getFCNames },
+    { ignoreViewer: true },
+  );
+}
+
 async function createPendingSidebar(
   input: CreatePendingSidebarInput,
 ): Promise<ThreadInfo> {
@@ -171,16 +192,12 @@
     getFCNames,
   } = input;
 
-  const messageTitleEntityText = getMessageTitle(
+  const messageTitle = await createSidebarTitle(
     sourceMessageInfo,
     parentThreadInfo,
-    parentThreadInfo,
     markdownRules,
-  );
-  const messageTitle = await getEntityTextAsString(
-    messageTitleEntityText,
-    { getENSNames, getFCNames },
-    { ignoreViewer: true },
+    getENSNames,
+    getFCNames,
   );
   invariant(
     messageTitle !== null && messageTitle !== undefined,
@@ -250,4 +267,5 @@
   useCanCreateSidebarFromMessage,
   useSidebarExistsOrCanBeCreated,
   createSidebarThreadName,
+  createSidebarTitle,
 };
diff --git a/lib/utils/__mocks__/config.js b/lib/utils/__mocks__/config.js
--- a/lib/utils/__mocks__/config.js
+++ b/lib/utils/__mocks__/config.js
@@ -70,6 +70,9 @@
   },
   showAlert: jest.fn(),
   isStaffRelease: false,
+  getDefaultTextMessageRules: jest.fn(() => ({
+    simpleMarkdownRules: {},
+  })),
 });
 
 const hasConfig = (): boolean => true;
diff --git a/lib/utils/config.js b/lib/utils/config.js
--- a/lib/utils/config.js
+++ b/lib/utils/config.js
@@ -6,11 +6,13 @@
 import type { CallSingleKeyserverEndpoint } from '../keyserver-conn/call-single-keyserver-endpoint.js';
 import type { CallKeyserverEndpoint } from '../keyserver-conn/keyserver-conn-types.js';
 import type { InitialNotifMessageOptions } from '../shared/crypto-utils.js';
+import type { ParserRules } from '../shared/markdown.js';
 import type { RecoveryActionSource } from '../types/account-types.js';
 import type { OlmAPI } from '../types/crypto-types.js';
 import type { PlatformDetails } from '../types/device-types.js';
 import type { EncryptedNotifUtilsAPI } from '../types/notif-types.js';
 import type { SQLiteAPI } from '../types/sqlite-types.js';
+import type { ChatMentionCandidates } from '../types/thread-types.js';
 
 export type Config = {
   +resolveKeyserverSessionInvalidationUsingNativeCredentials: ?(
@@ -44,6 +46,9 @@
     },
   ) => mixed,
   +isStaffRelease: boolean,
+  +getDefaultTextMessageRules: (
+    chatMentionCandidates?: ChatMentionCandidates,
+  ) => { +simpleMarkdownRules: ParserRules, ... },
 };
 
 let registeredConfig: ?Config = null;
diff --git a/native/config.js b/native/config.js
--- a/native/config.js
+++ b/native/config.js
@@ -9,6 +9,7 @@
 import { authoritativeKeyserverID } from './authoritative-keyserver.js';
 import { olmAPI } from './crypto/olm-api.js';
 import { sqliteAPI } from './database/sqlite-api.js';
+import { getDefaultTextMessageRules } from './markdown/rules.react.js';
 import encryptedNotifUtilsAPI from './push/encrypted-notif-utils-api.js';
 import { persistConfig, codeVersion } from './redux/persist.js';
 import Alert from './utils/alert.js';
@@ -56,4 +57,5 @@
     Alert.alert(title, message, alertButtons, alertOptions);
   },
   isStaffRelease: __DEV__ || isStaffRelease,
+  getDefaultTextMessageRules,
 });
diff --git a/web/app.react.js b/web/app.react.js
--- a/web/app.react.js
+++ b/web/app.react.js
@@ -80,6 +80,7 @@
 import InviteLinkHandler from './invite-links/invite-link-handler.react.js';
 import InviteLinksRefresher from './invite-links/invite-links-refresher.react.js';
 import LoadingIndicator from './loading-indicator.react.js';
+import { getDefaultTextMessageRules } from './markdown/rules.react.js';
 import { MenuProvider } from './menu-provider.react.js';
 import UpdateModalHandler from './modals/update-modal.react.js';
 import SettingsSwitcher from './navigation-panels/settings-switcher.react.js';
@@ -144,6 +145,7 @@
   showAlert: (title: string, message: string) =>
     window.alert(`${title}: ${message}`),
   isStaffRelease: isDev,
+  getDefaultTextMessageRules,
 });
 
 const versionBroadcast = new BroadcastChannel('comm_version');