diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -1027,7 +1027,7 @@
   +searching: boolean,
   +userInfoInputArray: $ReadOnlyArray<AccountUserInfo>,
 };
-type ExistingThreadInfoFinder = (
+export type ExistingThreadInfoFinder = (
   params: ExistingThreadInfoFinderParams,
 ) => ?ThreadInfo;
 function useExistingThreadInfoFinder(
diff --git a/web/chat/chat-message-list-container.react.js b/web/chat/chat-message-list-container.react.js
--- a/web/chat/chat-message-list-container.react.js
+++ b/web/chat/chat-message-list-container.react.js
@@ -215,6 +215,9 @@
       <ChatThreadComposer
         userInfoInputArray={userInfoInputArray}
         setUserInfoInputArray={setUserInfoInputArray}
+        existingThreadInfoFinderForCreatingThread={
+          existingThreadInfoFinderForCreatingThread
+        }
         otherUserInfos={otherUserInfos}
         threadID={threadInfo.id}
         inputState={inputState}
@@ -232,6 +235,7 @@
       </>
     );
   }, [
+    existingThreadInfoFinderForCreatingThread,
     inputState,
     isChatCreation,
     otherUserInfos,
diff --git a/web/chat/chat-thread-composer.react.js b/web/chat/chat-thread-composer.react.js
--- a/web/chat/chat-thread-composer.react.js
+++ b/web/chat/chat-thread-composer.react.js
@@ -1,13 +1,19 @@
 // @flow
 import classNames from 'classnames';
+import invariant from 'invariant';
 import * as React from 'react';
 import { useDispatch } from 'react-redux';
 
 import { searchUsers } from 'lib/actions/user-actions';
+import { useModalContext } from 'lib/components/modal-provider.react';
 import { filterPotentialMembers } from 'lib/selectors/user-selectors';
 import SearchIndex from 'lib/shared/search-index';
-import { getPotentialMemberItems } from 'lib/shared/search-utils';
+import {
+  getPotentialMemberItems,
+  notFriendNotice,
+} from 'lib/shared/search-utils';
 import { threadIsPending } from 'lib/shared/thread-utils';
+import type { ExistingThreadInfoFinder } from 'lib/shared/thread-utils';
 import type { AccountUserInfo, UserListItem } from 'lib/types/user-types';
 import { useServerCall } from 'lib/utils/action-utils';
 
@@ -15,6 +21,7 @@
 import Label from '../components/label.react';
 import Search from '../components/search.react';
 import type { InputState } from '../input/input-state';
+import Alert from '../modals/alert.react';
 import { updateNavInfoActionType } from '../redux/action-types';
 import { useSelector } from '../redux/redux-utils';
 import SWMansionIcon from '../SWMansionIcon.react';
@@ -23,8 +30,10 @@
 type Props = {
   +userInfoInputArray: $ReadOnlyArray<AccountUserInfo>,
   +setUserInfoInputArray: (
-    ($ReadOnlyArray<AccountUserInfo>) => $ReadOnlyArray<AccountUserInfo>,
+    | (($ReadOnlyArray<AccountUserInfo>) => $ReadOnlyArray<AccountUserInfo>)
+    | $ReadOnlyArray<AccountUserInfo>,
   ) => void,
+  +existingThreadInfoFinderForCreatingThread: ExistingThreadInfoFinder,
   +otherUserInfos: { [id: string]: AccountUserInfo },
   +threadID: string,
   +inputState: InputState,
@@ -38,6 +47,7 @@
   const {
     userInfoInputArray,
     setUserInfoInputArray,
+    existingThreadInfoFinderForCreatingThread,
     otherUserInfos,
     threadID,
     inputState,
@@ -107,15 +117,50 @@
     [usernameInputText, mergedUserInfos, userSearchIndex, userInfoInputIDs],
   );
 
+  const dispatch = useDispatch();
+  const { pushModal } = useModalContext();
   const onSelectUserFromSearch = React.useCallback(
-    (id: string, username: string) => {
-      setUserInfoInputArray(previousUserInfoInputArray => [
-        ...previousUserInfoInputArray,
-        { id, username },
-      ]);
+    (userItem: UserListItem) => {
       setUsernameInputText('');
+      if (!userItem.alertTitle) {
+        setUserInfoInputArray(previousUserInfoInputArray => [
+          ...previousUserInfoInputArray,
+          { id: userItem.id, username: userItem.username },
+        ]);
+      } else if (
+        userItem.notice === notFriendNotice &&
+        userInfoInputArray.length === 0
+      ) {
+        const newUserInfoInputArray = [
+          { id: userItem.id, username: userItem.username },
+        ];
+        setUserInfoInputArray(newUserInfoInputArray);
+        const threadInfo = existingThreadInfoFinderForCreatingThread({
+          searching: true,
+          userInfoInputArray: newUserInfoInputArray,
+        });
+        dispatch({
+          type: updateNavInfoActionType,
+          payload: {
+            chatMode: 'view',
+            activeChatThreadID: threadInfo?.id,
+            pendingThread: threadInfo,
+          },
+        });
+      } else {
+        invariant(userItem.alertText, 'alert should have both title and text');
+        pushModal(
+          <Alert title={userItem.alertTitle}>{userItem.alertText}</Alert>,
+        );
+      }
     },
-    [setUserInfoInputArray],
+    [
+      dispatch,
+      existingThreadInfoFinderForCreatingThread,
+      pushModal,
+      setUserInfoInputArray,
+      userInfoInputArray.length,
+    ],
   );
 
   const onRemoveUserFromSelected = React.useCallback(
@@ -141,16 +186,11 @@
           <li key={userSearchResult.id} className={css.searchResultsItem}>
             <Button
               variant="text"
-              onClick={() =>
-                onSelectUserFromSearch(
-                  userSearchResult.id,
-                  userSearchResult.username,
-                )
-              }
+              onClick={() => onSelectUserFromSearch(userSearchResult)}
               className={css.searchResultsButton}
             >
               <div className={css.userName}>{userSearchResult.username}</div>
-              <div className={css.userInfo}>{userSearchResult.alertTitle}</div>
+              <div className={css.userInfo}>{userSearchResult.notice}</div>
             </Button>
           </li>
         ))}
@@ -163,7 +203,6 @@
     usernameInputText,
   ]);
 
-  const dispatch = useDispatch();
   const hideSearch = React.useCallback(
     (threadBehavior: ActiveThreadBehavior = 'keep-active-thread') => {
       dispatch({