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
@@ -8,15 +8,8 @@
 import { NativeTypes } from 'react-dnd-html5-backend';
 import { useDispatch } from 'react-redux';
 
-import { threadInfoSelector } from 'lib/selectors/thread-selectors.js';
 import { userInfoSelectorForPotentialMembers } from 'lib/selectors/user-selectors.js';
-import {
-  useWatchThread,
-  useExistingThreadInfoFinder,
-  createPendingThread,
-  threadIsPending,
-} from 'lib/shared/thread-utils.js';
-import { threadTypes } from 'lib/types/thread-types.js';
+import { useWatchThread, threadIsPending } from 'lib/shared/thread-utils.js';
 import type { AccountUserInfo } from 'lib/types/user-types.js';
 
 import ChatInputBar from './chat-input-bar.react.js';
@@ -27,6 +20,7 @@
 import { InputStateContext } from '../input/input-state.js';
 import { updateNavInfoActionType } from '../redux/action-types.js';
 import { useSelector } from '../redux/redux-utils.js';
+import { useThreadInfoForPossiblyPendingThread } from '../utils/thread-utils.js';
 
 type Props = {
   +activeChatThreadID: string,
@@ -46,64 +40,9 @@
   const viewerID = useSelector(state => state.currentUserInfo?.id);
   invariant(viewerID, 'should be set');
 
-  const pendingPrivateThread = React.useRef(
-    createPendingThread({
-      viewerID,
-      threadType: threadTypes.PRIVATE,
-    }),
-  );
-
-  const newThreadID = 'pending/new_thread';
-  const pendingNewThread = React.useMemo(
-    () => ({
-      ...createPendingThread({
-        viewerID,
-        threadType: threadTypes.PRIVATE,
-        name: 'New thread',
-      }),
-      id: newThreadID,
-    }),
-    [viewerID],
-  );
-
-  const existingThreadInfoFinderForCreatingThread = useExistingThreadInfoFinder(
-    pendingPrivateThread.current,
-  );
-
-  const baseThreadInfo = useSelector(state => {
-    if (!activeChatThreadID) {
-      return null;
-    }
-    return (
-      threadInfoSelector(state)[activeChatThreadID] ??
-      state.navInfo.pendingThread
-    );
+  const threadInfo = useThreadInfoForPossiblyPendingThread({
+    activeChatThreadID,
   });
-  const existingThreadInfoFinder = useExistingThreadInfoFinder(baseThreadInfo);
-  const threadInfo = React.useMemo(() => {
-    if (isChatCreation) {
-      if (userInfoInputArray.length === 0) {
-        return pendingNewThread;
-      }
-
-      return existingThreadInfoFinderForCreatingThread({
-        searching: true,
-        userInfoInputArray,
-      });
-    }
-
-    return existingThreadInfoFinder({
-      searching: false,
-      userInfoInputArray: [],
-    });
-  }, [
-    existingThreadInfoFinder,
-    existingThreadInfoFinderForCreatingThread,
-    isChatCreation,
-    userInfoInputArray,
-    pendingNewThread,
-  ]);
-  invariant(threadInfo, 'ThreadInfo should be set');
 
   const dispatch = useDispatch();
 
diff --git a/web/utils/thread-utils.js b/web/utils/thread-utils.js
new file mode 100644
--- /dev/null
+++ b/web/utils/thread-utils.js
@@ -0,0 +1,96 @@
+// @flow
+
+import invariant from 'invariant';
+import * as React from 'react';
+
+import { threadInfoSelector } from 'lib/selectors/thread-selectors.js';
+import { userInfoSelectorForPotentialMembers } from 'lib/selectors/user-selectors.js';
+import {
+  createPendingThread,
+  useExistingThreadInfoFinder,
+} from 'lib/shared/thread-utils.js';
+import type { ThreadInfo } from 'lib/types/thread-types.js';
+import { threadTypes } from 'lib/types/thread-types.js';
+import type { AccountUserInfo } from 'lib/types/user-types.js';
+
+import { useSelector } from '../redux/redux-utils.js';
+
+type Props = {
+  +activeChatThreadID: string,
+};
+
+function useThreadInfoForPossiblyPendingThread(props: Props): ThreadInfo {
+  const { activeChatThreadID } = props;
+
+  const isChatCreation =
+    useSelector(state => state.navInfo.chatMode) === 'create';
+  const selectedUserIDs = useSelector(state => state.navInfo.selectedUserList);
+  const otherUserInfos = useSelector(userInfoSelectorForPotentialMembers);
+  const userInfoInputArray: $ReadOnlyArray<AccountUserInfo> = React.useMemo(
+    () => selectedUserIDs?.map(id => otherUserInfos[id]).filter(Boolean) ?? [],
+    [otherUserInfos, selectedUserIDs],
+  );
+  const viewerID = useSelector(state => state.currentUserInfo?.id);
+  invariant(viewerID, 'should be set');
+  const newThreadID = 'pending/new_thread';
+
+  const pendingNewThread = React.useMemo(
+    () => ({
+      ...createPendingThread({
+        viewerID,
+        threadType: threadTypes.PRIVATE,
+        name: 'New thread',
+      }),
+      id: newThreadID,
+    }),
+    [viewerID],
+  );
+  const pendingPrivateThread = React.useRef(
+    createPendingThread({
+      viewerID,
+      threadType: threadTypes.PRIVATE,
+    }),
+  );
+  const existingThreadInfoFinderForCreatingThread = useExistingThreadInfoFinder(
+    pendingPrivateThread.current,
+  );
+
+  const baseThreadInfo = useSelector(state => {
+    if (!activeChatThreadID) {
+      return null;
+    }
+    return (
+      threadInfoSelector(state)[activeChatThreadID] ??
+      state.navInfo.pendingThread
+    );
+  });
+  const existingThreadInfoFinder = useExistingThreadInfoFinder(baseThreadInfo);
+  const threadInfo = React.useMemo(() => {
+    if (isChatCreation) {
+      if (userInfoInputArray.length === 0) {
+        return pendingNewThread;
+      }
+
+      return existingThreadInfoFinderForCreatingThread({
+        searching: true,
+        userInfoInputArray,
+      });
+    }
+
+    return existingThreadInfoFinder({
+      searching: false,
+      userInfoInputArray: [],
+    });
+  }, [
+    existingThreadInfoFinder,
+    existingThreadInfoFinderForCreatingThread,
+    isChatCreation,
+    userInfoInputArray,
+    pendingNewThread,
+  ]);
+  invariant(threadInfo, 'ThreadInfo should be set');
+
+  return threadInfo;
+}
+
+export { useThreadInfoForPossiblyPendingThread };