diff --git a/native/chat/chat-input-bar.react.js b/native/chat/chat-input-bar.react.js
--- a/native/chat/chat-input-bar.react.js
+++ b/native/chat/chat-input-bar.react.js
@@ -57,6 +57,7 @@
   threadActualMembers,
   checkIfDefaultMembersAreVoiced,
   draftKeyFromThreadID,
+  useThreadChatMentionCandidates,
 } from 'lib/shared/thread-utils.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
@@ -1258,13 +1259,17 @@
     parentThreadInfo,
   );
 
+  const chatMentionCandidates = useThreadChatMentionCandidates(
+    props.threadInfo,
+  );
+
   const messageEditingContext = React.useContext(MessageEditingContext);
 
   const editedMessageInfo = messageEditingContext?.editState.editedMessage;
   const editedMessagePreview = useMessagePreview(
     editedMessageInfo,
     props.threadInfo,
-    getDefaultTextMessageRules().simpleMarkdownRules,
+    getDefaultTextMessageRules(chatMentionCandidates).simpleMarkdownRules,
   );
   const editMessage = useEditMessage();
 
diff --git a/native/chat/message-list-types.js b/native/chat/message-list-types.js
--- a/native/chat/message-list-types.js
+++ b/native/chat/message-list-types.js
@@ -4,6 +4,7 @@
 import invariant from 'invariant';
 import * as React from 'react';
 
+import { useThreadChatMentionCandidates } from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/thread-types.js';
 import { type UserInfo } from 'lib/types/user-types.js';
 
@@ -35,7 +36,11 @@
   React.createContext<?MessageListContextType>();
 
 function useMessageListContext(threadInfo: ThreadInfo) {
-  const getTextMessageMarkdownRules = useTextMessageRulesFunc(threadInfo);
+  const chatMentionCandidates = useThreadChatMentionCandidates(threadInfo);
+  const getTextMessageMarkdownRules = useTextMessageRulesFunc(
+    threadInfo,
+    chatMentionCandidates,
+  );
   return React.useMemo(
     () => ({
       getTextMessageMarkdownRules,
diff --git a/native/chat/message-preview.react.js b/native/chat/message-preview.react.js
--- a/native/chat/message-preview.react.js
+++ b/native/chat/message-preview.react.js
@@ -5,6 +5,7 @@
 import { Text } from 'react-native';
 
 import { useMessagePreview } from 'lib/shared/message-utils.js';
+import { useThreadChatMentionCandidates } from 'lib/shared/thread-utils.js';
 import { type MessageInfo } from 'lib/types/message-types.js';
 import { type ThreadInfo } from 'lib/types/thread-types.js';
 
@@ -18,10 +19,12 @@
 };
 function MessagePreview(props: Props): React.Node {
   const { messageInfo, threadInfo } = props;
+
+  const chatMentionCandidates = useThreadChatMentionCandidates(threadInfo);
   const messagePreviewResult = useMessagePreview(
     messageInfo,
     threadInfo,
-    getDefaultTextMessageRules().simpleMarkdownRules,
+    getDefaultTextMessageRules(chatMentionCandidates).simpleMarkdownRules,
   );
   invariant(
     messagePreviewResult,
diff --git a/native/chat/sidebar-input-bar-height-measurer.react.js b/native/chat/sidebar-input-bar-height-measurer.react.js
--- a/native/chat/sidebar-input-bar-height-measurer.react.js
+++ b/native/chat/sidebar-input-bar-height-measurer.react.js
@@ -4,6 +4,7 @@
 import { View, StyleSheet } from 'react-native';
 
 import { useLoggedInUserInfo } from 'lib/hooks/account-hooks.js';
+import { useChatMentionCandidatesObj } from 'lib/shared/thread-utils.js';
 
 import { DummyChatInputBar } from './chat-input-bar.react.js';
 import { useMessageListScreenWidth } from './composed-message-width.js';
@@ -21,9 +22,15 @@
   const width = useMessageListScreenWidth();
 
   const loggedInUserInfo = useLoggedInUserInfo();
+  const chatMentionCandidatesObj = useChatMentionCandidatesObj();
   const sidebarThreadInfo = React.useMemo(
-    () => getUnresolvedSidebarThreadInfo({ sourceMessage, loggedInUserInfo }),
-    [sourceMessage, loggedInUserInfo],
+    () =>
+      getUnresolvedSidebarThreadInfo({
+        sourceMessage,
+        loggedInUserInfo,
+        chatMentionCandidatesObj,
+      }),
+    [sourceMessage, loggedInUserInfo, chatMentionCandidatesObj],
   );
   if (!sidebarThreadInfo) {
     return null;
diff --git a/native/chat/sidebar-navigation.js b/native/chat/sidebar-navigation.js
--- a/native/chat/sidebar-navigation.js
+++ b/native/chat/sidebar-navigation.js
@@ -8,8 +8,13 @@
 import {
   createPendingSidebar,
   createUnresolvedPendingSidebar,
+  useChatMentionCandidatesObj,
+  threadChatMentionCandidates,
 } from 'lib/shared/thread-utils.js';
-import type { ThreadInfo } from 'lib/types/thread-types.js';
+import type {
+  ThreadInfo,
+  ChatMentionCandidatesObj,
+} from 'lib/types/thread-types.js';
 import type { LoggedInUserInfo } from 'lib/types/user-types.js';
 import type { GetENSNames } from 'lib/utils/ens-helpers.js';
 
@@ -21,11 +26,12 @@
 type GetUnresolvedSidebarThreadInfoInput = {
   +sourceMessage: ChatMessageInfoItemWithHeight,
   +loggedInUserInfo: ?LoggedInUserInfo,
+  +chatMentionCandidatesObj: ChatMentionCandidatesObj,
 };
 function getUnresolvedSidebarThreadInfo(
   input: GetUnresolvedSidebarThreadInfoInput,
 ): ?ThreadInfo {
-  const { sourceMessage, loggedInUserInfo } = input;
+  const { sourceMessage, loggedInUserInfo, chatMentionCandidatesObj } = input;
   const threadCreatedFromMessage = sourceMessage.threadCreatedFromMessage;
   if (threadCreatedFromMessage) {
     return threadCreatedFromMessage;
@@ -36,22 +42,35 @@
   }
 
   const { messageInfo, threadInfo } = sourceMessage;
+  const chatMentionCandidates = threadChatMentionCandidates(
+    threadInfo,
+    chatMentionCandidatesObj,
+  );
+
   return createUnresolvedPendingSidebar({
     sourceMessageInfo: messageInfo,
     parentThreadInfo: threadInfo,
     loggedInUserInfo,
-    markdownRules: getDefaultTextMessageRules().simpleMarkdownRules,
+    markdownRules: getDefaultTextMessageRules(chatMentionCandidates)
+      .simpleMarkdownRules,
   });
 }
 
 type GetSidebarThreadInfoInput = {
-  ...GetUnresolvedSidebarThreadInfoInput,
+  +sourceMessage: ChatMessageInfoItemWithHeight,
+  +loggedInUserInfo: ?LoggedInUserInfo,
   +getENSNames: ?GetENSNames,
+  +chatMentionCandidatesObj: ChatMentionCandidatesObj,
 };
 async function getSidebarThreadInfo(
   input: GetSidebarThreadInfoInput,
 ): Promise<?ThreadInfo> {
-  const { sourceMessage, loggedInUserInfo, getENSNames } = input;
+  const {
+    sourceMessage,
+    loggedInUserInfo,
+    getENSNames,
+    chatMentionCandidatesObj,
+  } = input;
   const threadCreatedFromMessage = sourceMessage.threadCreatedFromMessage;
   if (threadCreatedFromMessage) {
     return threadCreatedFromMessage;
@@ -62,11 +81,17 @@
   }
 
   const { messageInfo, threadInfo } = sourceMessage;
+  const chatMentionCandidates = threadChatMentionCandidates(
+    threadInfo,
+    chatMentionCandidatesObj,
+  );
+
   return await createPendingSidebar({
     sourceMessageInfo: messageInfo,
     parentThreadInfo: threadInfo,
     loggedInUserInfo,
-    markdownRules: getDefaultTextMessageRules().simpleMarkdownRules,
+    markdownRules: getDefaultTextMessageRules(chatMentionCandidates)
+      .simpleMarkdownRules,
     getENSNames,
   });
 }
@@ -77,16 +102,24 @@
   const loggedInUserInfo = useLoggedInUserInfo();
   const navigateToThread = useNavigateToThread();
   const cacheContext = React.useContext(ENSCacheContext);
+  const chatMentionCandidatesObj = useChatMentionCandidatesObj();
   const { getENSNames } = cacheContext;
   return React.useCallback(async () => {
     const threadInfo = await getSidebarThreadInfo({
       sourceMessage: item,
       loggedInUserInfo,
       getENSNames,
+      chatMentionCandidatesObj,
     });
     invariant(threadInfo, 'threadInfo should be set');
     navigateToThread({ threadInfo });
-  }, [navigateToThread, item, loggedInUserInfo, getENSNames]);
+  }, [
+    item,
+    loggedInUserInfo,
+    getENSNames,
+    chatMentionCandidatesObj,
+    navigateToThread,
+  ]);
 }
 
 function useAnimatedNavigateToSidebar(
diff --git a/native/chat/utils.js b/native/chat/utils.js
--- a/native/chat/utils.js
+++ b/native/chat/utils.js
@@ -7,7 +7,10 @@
 import { useLoggedInUserInfo } from 'lib/hooks/account-hooks.js';
 import { colorIsDark } from 'lib/shared/color-utils.js';
 import { messageKey } from 'lib/shared/message-utils.js';
-import { viewerIsMember } from 'lib/shared/thread-utils.js';
+import {
+  viewerIsMember,
+  useChatMentionCandidatesObj,
+} from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/thread-types.js';
 
 import { clusterEndHeight } from './chat-constants.js';
@@ -206,9 +209,15 @@
   } = chatContext;
 
   const loggedInUserInfo = useLoggedInUserInfo();
+  const chatMentionCandidatesObj = useChatMentionCandidatesObj();
   const sidebarThreadInfo = React.useMemo(
-    () => getUnresolvedSidebarThreadInfo({ sourceMessage, loggedInUserInfo }),
-    [sourceMessage, loggedInUserInfo],
+    () =>
+      getUnresolvedSidebarThreadInfo({
+        sourceMessage,
+        loggedInUserInfo,
+        chatMentionCandidatesObj,
+      }),
+    [sourceMessage, loggedInUserInfo, chatMentionCandidatesObj],
   );
 
   const currentInputBarHeight =
diff --git a/native/markdown/rules.react.js b/native/markdown/rules.react.js
--- a/native/markdown/rules.react.js
+++ b/native/markdown/rules.react.js
@@ -6,7 +6,11 @@
 import * as SimpleMarkdown from 'simple-markdown';
 
 import * as SharedMarkdown from 'lib/shared/markdown.js';
-import type { RelativeMemberInfo, ThreadInfo } from 'lib/types/thread-types.js';
+import type {
+  RelativeMemberInfo,
+  ThreadInfo,
+  ChatMentionCandidates,
+} from 'lib/types/thread-types.js';
 
 import MarkdownLink from './markdown-link.react.js';
 import MarkdownParagraph from './markdown-paragraph.react.js';
@@ -353,19 +357,21 @@
 
 function useTextMessageRulesFunc(
   threadInfo: ThreadInfo,
+  chatMentionCandidates: ChatMentionCandidates,
 ): (useDarkStyle: boolean) => MarkdownRules {
   const { members } = threadInfo;
   return React.useMemo(
     () =>
       _memoize<[boolean], MarkdownRules>((useDarkStyle: boolean) =>
-        textMessageRules(members, useDarkStyle),
+        textMessageRules(members, chatMentionCandidates, useDarkStyle),
       ),
-    [members],
+    [members, chatMentionCandidates],
   );
 }
 
 function textMessageRules(
   members: $ReadOnlyArray<RelativeMemberInfo>,
+  chatMentionCandidates: ChatMentionCandidates,
   useDarkStyle: boolean,
 ): MarkdownRules {
   const styles = getMarkdownStyles(useDarkStyle ? 'dark' : 'light');
@@ -395,14 +401,11 @@
   };
 }
 
-let defaultTextMessageRules = null;
-
-function getDefaultTextMessageRules(): MarkdownRules {
-  if (!defaultTextMessageRules) {
-    defaultTextMessageRules = textMessageRules([], false);
-  }
-  return defaultTextMessageRules;
-}
+const getDefaultTextMessageRules: (
+  overrideDefaultChatMentionCandidates?: ChatMentionCandidates,
+) => MarkdownRules = _memoize((overrideDefaultChatMentionCandidates = {}) =>
+  textMessageRules([], overrideDefaultChatMentionCandidates, false),
+);
 
 export {
   inlineMarkdownRules,