diff --git a/web/avatars/edit-thread-avatar-menu.react.js b/web/avatars/edit-thread-avatar-menu.react.js
--- a/web/avatars/edit-thread-avatar-menu.react.js
+++ b/web/avatars/edit-thread-avatar-menu.react.js
@@ -10,7 +10,6 @@
   ThreadInfo,
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import { useUploadAvatarMedia } from './avatar-hooks.react.js';
 import css from './edit-avatar-menu.css';
@@ -26,7 +25,7 @@
 );
 
 type Props = {
-  +threadInfo: RawThreadInfo | LegacyThreadInfo | ThreadInfo,
+  +threadInfo: RawThreadInfo | ThreadInfo,
 };
 function EditThreadAvatarMenu(props: Props): React.Node {
   const { threadInfo } = props;
diff --git a/web/avatars/edit-thread-avatar.react.js b/web/avatars/edit-thread-avatar.react.js
--- a/web/avatars/edit-thread-avatar.react.js
+++ b/web/avatars/edit-thread-avatar.react.js
@@ -10,14 +10,13 @@
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import EditThreadAvatarMenu from './edit-thread-avatar-menu.react.js';
 import css from './edit-thread-avatar.css';
 import ThreadAvatar from './thread-avatar.react.js';
 
 type Props = {
-  +threadInfo: RawThreadInfo | LegacyThreadInfo | ThreadInfo,
+  +threadInfo: RawThreadInfo | ThreadInfo,
   +disabled?: boolean,
 };
 function EditThreadAvatar(props: Props): React.Node {
diff --git a/web/avatars/thread-avatar.react.js b/web/avatars/thread-avatar.react.js
--- a/web/avatars/thread-avatar.react.js
+++ b/web/avatars/thread-avatar.react.js
@@ -13,13 +13,12 @@
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import Avatar from './avatar.react.js';
 import { useSelector } from '../redux/redux-utils.js';
 
 type Props = {
-  +threadInfo: RawThreadInfo | LegacyThreadInfo | ThreadInfo,
+  +threadInfo: RawThreadInfo | ThreadInfo,
   +size: AvatarSize,
   +showSpinner?: boolean,
 };
diff --git a/web/avatars/thread-emoji-avatar-selection-modal.react.js b/web/avatars/thread-emoji-avatar-selection-modal.react.js
--- a/web/avatars/thread-emoji-avatar-selection-modal.react.js
+++ b/web/avatars/thread-emoji-avatar-selection-modal.react.js
@@ -16,12 +16,11 @@
   ThreadInfo,
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import EmojiAvatarSelectionModal from './emoji-avatar-selection-modal.react.js';
 
 type Props = {
-  +threadInfo: RawThreadInfo | LegacyThreadInfo | ThreadInfo,
+  +threadInfo: RawThreadInfo | ThreadInfo,
 };
 
 function ThreadEmojiAvatarSelectionModal(props: Props): React.Node {
diff --git a/web/calendar/day.react.js b/web/calendar/day.react.js
--- a/web/calendar/day.react.js
+++ b/web/calendar/day.react.js
@@ -18,7 +18,6 @@
 import type { EntryInfo } from 'lib/types/entry-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { Dispatch } from 'lib/types/redux-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { dateFromString, dateString } from 'lib/utils/date-utils.js';
 import { useDispatch } from 'lib/utils/redux-utils.js';
 
@@ -39,7 +38,7 @@
 };
 type Props = {
   ...BaseProps,
-  +onScreenThreadInfos: $ReadOnlyArray<LegacyThreadInfo | ThreadInfo>,
+  +onScreenThreadInfos: $ReadOnlyArray<ThreadInfo>,
   +viewerID: ?string,
   +loggedIn: boolean,
   +nextLocalID: number,
diff --git a/web/chat/chat-thread-list-item-menu.react.js b/web/chat/chat-thread-list-item-menu.react.js
--- a/web/chat/chat-thread-list-item-menu.react.js
+++ b/web/chat/chat-thread-list-item-menu.react.js
@@ -6,14 +6,13 @@
 import SWMansionIcon from 'lib/components/SWMansionIcon.react.js';
 import useToggleUnreadStatus from 'lib/hooks/toggle-unread-status.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './chat-thread-list-item-menu.css';
 import Button from '../components/button.react.js';
 import { useThreadIsActive } from '../selectors/thread-selectors.js';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +mostRecentNonLocalMessage: ?string,
   +renderStyle?: 'chat' | 'thread',
 };
diff --git a/web/chat/chat-thread-list-see-more-sidebars.react.js b/web/chat/chat-thread-list-see-more-sidebars.react.js
--- a/web/chat/chat-thread-list-see-more-sidebars.react.js
+++ b/web/chat/chat-thread-list-see-more-sidebars.react.js
@@ -6,13 +6,12 @@
 
 import { useModalContext } from 'lib/components/modal-provider.react.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './chat-thread-list.css';
 import SidebarsModal from '../modals/threads/sidebars/sidebars-modal.react.js';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +unread: boolean,
 };
 function ChatThreadListSeeMoreSidebars(props: Props): React.Node {
diff --git a/web/chat/inline-engagement.react.js b/web/chat/inline-engagement.react.js
--- a/web/chat/inline-engagement.react.js
+++ b/web/chat/inline-engagement.react.js
@@ -8,7 +8,6 @@
 import { getInlineEngagementSidebarText } from 'lib/shared/inline-engagement-utils.js';
 import type { MessageInfo } from 'lib/types/message-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './inline-engagement.css';
 import ReactionPill from './reaction-pill.react.js';
@@ -17,8 +16,8 @@
 
 type Props = {
   +messageInfo: MessageInfo,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
-  +sidebarThreadInfo: ?LegacyThreadInfo | ?ThreadInfo,
+  +threadInfo: ThreadInfo,
+  +sidebarThreadInfo: ?ThreadInfo,
   +reactions: ReactionInfo,
   +positioning: 'left' | 'center' | 'right',
   +label?: ?string,
diff --git a/web/chat/message-preview.react.js b/web/chat/message-preview.react.js
--- a/web/chat/message-preview.react.js
+++ b/web/chat/message-preview.react.js
@@ -8,14 +8,13 @@
 import { useMessagePreview } from 'lib/shared/message-utils.js';
 import { type MessageInfo } from 'lib/types/message-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './chat-thread-list.css';
 import { getDefaultTextMessageRules } from '../markdown/rules.react.js';
 
 type Props = {
   +messageInfo: ?MessageInfo,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 function MessagePreview(props: Props): React.Node {
   const { messageInfo, threadInfo } = props;
diff --git a/web/chat/relationship-prompt/relationship-prompt.js b/web/chat/relationship-prompt/relationship-prompt.js
--- a/web/chat/relationship-prompt/relationship-prompt.js
+++ b/web/chat/relationship-prompt/relationship-prompt.js
@@ -11,13 +11,12 @@
 import { useRelationshipPrompt } from 'lib/hooks/relationship-prompt.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { userRelationshipStatus } from 'lib/types/relationship-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import RelationshipPromptButtonContainer from './relationship-prompt-button-container.js';
 import RelationshipPromptButton from './relationship-prompt-button.js';
 import { buttonThemes } from '../../components/button.react.js';
 
-type Props = { +threadInfo: LegacyThreadInfo | ThreadInfo };
+type Props = { +threadInfo: ThreadInfo };
 
 function RelationshipPrompt(props: Props) {
   const { threadInfo } = props;
diff --git a/web/chat/robotext-message.react.js b/web/chat/robotext-message.react.js
--- a/web/chat/robotext-message.react.js
+++ b/web/chat/robotext-message.react.js
@@ -7,7 +7,6 @@
 import { threadInfoSelector } from 'lib/selectors/thread-selectors.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { Dispatch } from 'lib/types/redux-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import {
   entityTextToReact,
   useENSNamesForEntityText,
@@ -101,7 +100,7 @@
 };
 type InnerThreadEntityProps = {
   ...BaseInnerThreadEntityProps,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +dispatch: Dispatch,
 };
 class InnerThreadEntity extends React.PureComponent<InnerThreadEntityProps> {
diff --git a/web/input/input-state-container.react.js b/web/input/input-state-container.react.js
--- a/web/input/input-state-container.react.js
+++ b/web/input/input-state-container.react.js
@@ -80,7 +80,6 @@
 import {
   type ClientNewThreadRequest,
   type NewThreadResult,
-  type LegacyThreadInfo,
 } from 'lib/types/thread-types.js';
 import { useLegacyAshoatKeyserverCall } from 'lib/utils/action-utils.js';
 import {
@@ -420,7 +419,7 @@
     return rawMessageInfo;
   }
 
-  shouldEncryptMedia(threadInfo: LegacyThreadInfo | ThreadInfo): boolean {
+  shouldEncryptMedia(threadInfo: ThreadInfo): boolean {
     return threadInfoInsideCommunity(threadInfo, commStaffCommunity.id);
   }
 
@@ -566,9 +565,7 @@
     }
   }
 
-  startThreadCreation(
-    threadInfo: LegacyThreadInfo | ThreadInfo,
-  ): Promise<string> {
+  startThreadCreation(threadInfo: ThreadInfo): Promise<string> {
     if (!threadIsPending(threadInfo.id)) {
       return Promise.resolve(threadInfo.id);
     }
@@ -629,7 +626,7 @@
             draft: draft ?? '',
             textCursorPosition: textCursorPosition ?? 0,
             appendFiles: (
-              threadInfo: LegacyThreadInfo | ThreadInfo,
+              threadInfo: ThreadInfo,
               files: $ReadOnlyArray<File>,
             ) => this.appendFiles(threadInfo, files),
             cancelPendingUpload: (localUploadID: string) =>
@@ -642,7 +639,7 @@
               this.sendTextMessage(messageInfo, threadInfo, parentThreadInfo),
             createMultimediaMessage: (
               localID: number,
-              threadInfo: LegacyThreadInfo | ThreadInfo,
+              threadInfo: ThreadInfo,
             ) => this.createMultimediaMessage(localID, threadInfo),
             setDraft: (newDraft: string) => this.setDraft(threadID, newDraft),
             setTextCursorPosition: (newPosition: number) =>
@@ -651,7 +648,7 @@
               this.messageHasUploadFailure(assignedUploads[localMessageID]),
             retryMultimediaMessage: (
               localMessageID: string,
-              threadInfo: LegacyThreadInfo | ThreadInfo,
+              threadInfo: ThreadInfo,
             ) =>
               this.retryMultimediaMessage(
                 localMessageID,
@@ -690,7 +687,7 @@
   }
 
   async appendFiles(
-    threadInfo: LegacyThreadInfo | ThreadInfo,
+    threadInfo: ThreadInfo,
     files: $ReadOnlyArray<File>,
   ): Promise<boolean> {
     const selectionTime = Date.now();
@@ -747,7 +744,7 @@
   }
 
   async appendFile(
-    threadInfo: LegacyThreadInfo | ThreadInfo,
+    threadInfo: ThreadInfo,
     file: File,
     selectTime: number,
   ): Promise<{
@@ -1342,8 +1339,8 @@
 
   async sendTextMessageAction(
     messageInfo: RawTextMessageInfo,
-    threadInfo: LegacyThreadInfo | ThreadInfo,
-    parentThreadInfo: ?LegacyThreadInfo | ?ThreadInfo,
+    threadInfo: ThreadInfo,
+    parentThreadInfo: ?ThreadInfo,
   ): Promise<SendMessagePayload> {
     try {
       await this.props.textMessageCreationSideEffectsFunc(
@@ -1382,10 +1379,7 @@
 
   // Creates a MultimediaMessage from the unassigned pending uploads,
   // if there are any
-  createMultimediaMessage(
-    localID: number,
-    threadInfo: LegacyThreadInfo | ThreadInfo,
-  ) {
+  createMultimediaMessage(localID: number, threadInfo: ThreadInfo) {
     this.props.sendCallbacks.forEach(callback => callback());
 
     const localMessageID = `${localIDPrefix}${localID}`;
@@ -1506,7 +1500,7 @@
 
   retryMultimediaMessage(
     localMessageID: string,
-    threadInfo: LegacyThreadInfo | ThreadInfo,
+    threadInfo: ThreadInfo,
     pendingUploads: ?$ReadOnlyArray<PendingMultimediaUpload>,
   ) {
     this.props.sendCallbacks.forEach(callback => callback());
diff --git a/web/input/input-state.js b/web/input/input-state.js
--- a/web/input/input-state.js
+++ b/web/input/input-state.js
@@ -12,7 +12,6 @@
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type {
   ChatMentionCandidates,
-  LegacyThreadInfo,
   RelativeMemberInfo,
 } from 'lib/types/thread-types.js';
 
@@ -64,7 +63,7 @@
   +draft: string,
   +textCursorPosition: number,
   +appendFiles: (
-    threadInfo: LegacyThreadInfo | ThreadInfo,
+    threadInfo: ThreadInfo,
     files: $ReadOnlyArray<File>,
   ) => Promise<boolean>,
   +cancelPendingUpload: (localUploadID: string) => void,
@@ -73,16 +72,13 @@
     threadInfo: ThreadInfo,
     parentThreadInfo: ?ThreadInfo,
   ) => mixed,
-  +createMultimediaMessage: (
-    localID: number,
-    threadInfo: LegacyThreadInfo | ThreadInfo,
-  ) => void,
+  +createMultimediaMessage: (localID: number, threadInfo: ThreadInfo) => void,
   +setDraft: (draft: string) => void,
   +setTextCursorPosition: (newPosition: number) => void,
   +messageHasUploadFailure: (localMessageID: string) => boolean,
   +retryMultimediaMessage: (
     localMessageID: string,
-    threadInfo: LegacyThreadInfo | ThreadInfo,
+    threadInfo: ThreadInfo,
   ) => void,
   +addReply: (text: string) => void,
   +addReplyListener: ((message: string) => void) => void,
diff --git a/web/invite-links/manage/edit-link-modal.react.js b/web/invite-links/manage/edit-link-modal.react.js
--- a/web/invite-links/manage/edit-link-modal.react.js
+++ b/web/invite-links/manage/edit-link-modal.react.js
@@ -12,7 +12,6 @@
 } from 'lib/shared/invite-links.js';
 import type { InviteLink } from 'lib/types/link-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './manage-invite-links-modal.css';
 import Button from '../../components/button.react.js';
@@ -23,7 +22,7 @@
   +inviteLink: ?InviteLink,
   +enterViewMode: () => mixed,
   +enterDisableMode: () => mixed,
-  +community: LegacyThreadInfo | ThreadInfo,
+  +community: ThreadInfo,
 };
 
 const disableButtonColor = {
diff --git a/web/markdown/rules.react.js b/web/markdown/rules.react.js
--- a/web/markdown/rules.react.js
+++ b/web/markdown/rules.react.js
@@ -7,10 +7,7 @@
 import * as SharedMarkdown from 'lib/shared/markdown.js';
 import { chatMentionRegex } from 'lib/shared/mention-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type {
-  ChatMentionCandidates,
-  LegacyThreadInfo,
-} from 'lib/types/thread-types.js';
+import type { ChatMentionCandidates } from 'lib/types/thread-types.js';
 
 import MarkdownChatMention from './markdown-chat-mention.react.js';
 import MarkdownSpoiler from './markdown-spoiler.react.js';
@@ -162,7 +159,7 @@
 });
 
 function useTextMessageRulesFunc(
-  threadInfo: LegacyThreadInfo | ThreadInfo,
+  threadInfo: ThreadInfo,
   chatMentionCandidates: ChatMentionCandidates,
 ): boolean => MarkdownRules {
   const { members } = threadInfo;
diff --git a/web/modals/search/message-search-utils.react.js b/web/modals/search/message-search-utils.react.js
--- a/web/modals/search/message-search-utils.react.js
+++ b/web/modals/search/message-search-utils.react.js
@@ -13,12 +13,11 @@
 import { filterChatMessageInfosForSearch } from 'lib/shared/search-utils.js';
 import type { RawMessageInfo } from 'lib/types/message-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import { useSelector } from '../../redux/redux-utils.js';
 
 function useParseSearchResults(
-  threadInfo: LegacyThreadInfo | ThreadInfo,
+  threadInfo: ThreadInfo,
   searchResults: $ReadOnlyArray<RawMessageInfo>,
 ): $ReadOnlyArray<ChatMessageInfoItem> {
   const userInfos = useSelector(state => state.userStore.userInfos);
diff --git a/web/modals/threads/create/steps/subchannel-members-list.react.js b/web/modals/threads/create/steps/subchannel-members-list.react.js
--- a/web/modals/threads/create/steps/subchannel-members-list.react.js
+++ b/web/modals/threads/create/steps/subchannel-members-list.react.js
@@ -5,10 +5,7 @@
 import { useENSNames } from 'lib/hooks/ens-cache.js';
 import { stringForUser } from 'lib/shared/user-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type {
-  LegacyThreadInfo,
-  RelativeMemberInfo,
-} from 'lib/types/thread-types.js';
+import type { RelativeMemberInfo } from 'lib/types/thread-types.js';
 import type { UserListItem } from 'lib/types/user-types.js';
 
 import { useSelector } from '../../../../redux/redux-utils.js';
@@ -17,8 +14,8 @@
 type Props = {
   +searchText: string,
   +searchResult: $ReadOnlySet<string>,
-  +communityThreadInfo: LegacyThreadInfo | ThreadInfo,
-  +parentThreadInfo: LegacyThreadInfo | ThreadInfo,
+  +communityThreadInfo: ThreadInfo,
+  +parentThreadInfo: ThreadInfo,
   +selectedUsers: $ReadOnlySet<string>,
   +toggleUserSelection: (userID: string) => void,
 };
diff --git a/web/modals/threads/gallery/thread-settings-media-gallery.react.js b/web/modals/threads/gallery/thread-settings-media-gallery.react.js
--- a/web/modals/threads/gallery/thread-settings-media-gallery.react.js
+++ b/web/modals/threads/gallery/thread-settings-media-gallery.react.js
@@ -11,7 +11,6 @@
 } from 'lib/media/media-utils.js';
 import type { Media } from 'lib/types/media-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import GalleryItem from './thread-settings-media-gallery-item.react.js';
 import css from './thread-settings-media-gallery.css';
@@ -38,7 +37,7 @@
 
 type ThreadSettingsMediaGalleryModalProps = {
   +onClose: () => void,
-  +parentThreadInfo: LegacyThreadInfo | ThreadInfo,
+  +parentThreadInfo: ThreadInfo,
   +limit: number,
   +activeTab: MediaGalleryTab,
 };
diff --git a/web/modals/threads/members/change-member-role-modal.react.js b/web/modals/threads/members/change-member-role-modal.react.js
--- a/web/modals/threads/members/change-member-role-modal.react.js
+++ b/web/modals/threads/members/change-member-role-modal.react.js
@@ -12,10 +12,7 @@
 import { otherUsersButNoOtherAdmins } from 'lib/selectors/thread-selectors.js';
 import { roleIsAdminRole } from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type {
-  LegacyThreadInfo,
-  RelativeMemberInfo,
-} from 'lib/types/thread-types';
+import type { RelativeMemberInfo } from 'lib/types/thread-types';
 import { values } from 'lib/utils/objects.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 
@@ -29,7 +26,7 @@
 
 type ChangeMemberRoleModalProps = {
   +memberInfo: RelativeMemberInfo,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function ChangeMemberRoleModal(props: ChangeMemberRoleModalProps): React.Node {
diff --git a/web/modals/threads/members/member.react.js b/web/modals/threads/members/member.react.js
--- a/web/modals/threads/members/member.react.js
+++ b/web/modals/threads/members/member.react.js
@@ -12,10 +12,7 @@
 import { stringForUser } from 'lib/shared/user-utils.js';
 import type { SetState } from 'lib/types/hook-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type {
-  LegacyThreadInfo,
-  RelativeMemberInfo,
-} from 'lib/types/thread-types.js';
+import type { RelativeMemberInfo } from 'lib/types/thread-types.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 import { useRolesFromCommunityThreadInfo } from 'lib/utils/role-utils.js';
 
@@ -32,7 +29,7 @@
 
 type Props = {
   +memberInfo: RelativeMemberInfo,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +setOpenMenu: SetState<?string>,
 };
 
diff --git a/web/modals/threads/members/members-list.react.js b/web/modals/threads/members/members-list.react.js
--- a/web/modals/threads/members/members-list.react.js
+++ b/web/modals/threads/members/members-list.react.js
@@ -8,16 +8,13 @@
 import { useENSNames } from 'lib/hooks/ens-cache.js';
 import { stringForUser } from 'lib/shared/user-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import {
-  type RelativeMemberInfo,
-  type LegacyThreadInfo,
-} from 'lib/types/thread-types.js';
+import { type RelativeMemberInfo } from 'lib/types/thread-types.js';
 
 import ThreadMember from './member.react.js';
 import css from './members-modal.css';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +threadMembers: $ReadOnlyArray<RelativeMemberInfo>,
 };
 
diff --git a/web/modals/threads/settings/thread-settings-delete-confirmation-modal.react.js b/web/modals/threads/settings/thread-settings-delete-confirmation-modal.react.js
--- a/web/modals/threads/settings/thread-settings-delete-confirmation-modal.react.js
+++ b/web/modals/threads/settings/thread-settings-delete-confirmation-modal.react.js
@@ -5,14 +5,13 @@
 import { useModalContext } from 'lib/components/modal-provider.react.js';
 import { getThreadsToDeleteText } from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types';
 
 import css from './thread-settings-delete-confirmation-modal.css';
 import Button from '../../../components/button.react.js';
 import Modal from '../../modal.react.js';
 
 type BaseProps = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +onConfirmation: () => mixed,
 };
 
diff --git a/web/modals/threads/settings/thread-settings-delete-tab.react.js b/web/modals/threads/settings/thread-settings-delete-tab.react.js
--- a/web/modals/threads/settings/thread-settings-delete-tab.react.js
+++ b/web/modals/threads/settings/thread-settings-delete-tab.react.js
@@ -11,7 +11,6 @@
 import { containedThreadInfos } from 'lib/selectors/thread-selectors.js';
 import { type SetState } from 'lib/types/hook-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 
 import SubmitSection from './submit-section.react.js';
@@ -22,7 +21,7 @@
 
 type ThreadSettingsDeleteTabProps = {
   +threadSettingsOperationInProgress: boolean,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +setErrorMessage: SetState<?string>,
   +errorMessage?: ?string,
 };
diff --git a/web/modals/threads/settings/thread-settings-general-tab.react.js b/web/modals/threads/settings/thread-settings-general-tab.react.js
--- a/web/modals/threads/settings/thread-settings-general-tab.react.js
+++ b/web/modals/threads/settings/thread-settings-general-tab.react.js
@@ -11,10 +11,7 @@
 import { type SetState } from 'lib/types/hook-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import {
-  type ThreadChanges,
-  type LegacyThreadInfo,
-} from 'lib/types/thread-types.js';
+import { type ThreadChanges } from 'lib/types/thread-types.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 import { firstLine } from 'lib/utils/string-utils.js';
 import { chatNameMaxLength } from 'lib/utils/validation-utils.js';
@@ -28,7 +25,7 @@
 
 type ThreadSettingsGeneralTabProps = {
   +threadSettingsOperationInProgress: boolean,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +threadNamePlaceholder: string,
   +queuedChanges: ThreadChanges,
   +setQueuedChanges: SetState<ThreadChanges>,
diff --git a/web/modals/threads/settings/thread-settings-modal.react.js b/web/modals/threads/settings/thread-settings-modal.react.js
--- a/web/modals/threads/settings/thread-settings-modal.react.js
+++ b/web/modals/threads/settings/thread-settings-modal.react.js
@@ -20,10 +20,7 @@
 import type { RelationshipButton } from 'lib/types/relationship-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
-import {
-  type ThreadChanges,
-  type LegacyThreadInfo,
-} from 'lib/types/thread-types.js';
+import { type ThreadChanges } from 'lib/types/thread-types.js';
 import { useResolvedThreadInfo } from 'lib/utils/entity-helpers.js';
 
 import ThreadSettingsDeleteTab from './thread-settings-delete-tab.react.js';
@@ -101,7 +98,7 @@
     const hasPermissionForTab = React.useCallback(
       // ESLint doesn't recognize that invariant always throws
       // eslint-disable-next-line consistent-return
-      (thread: LegacyThreadInfo | ThreadInfo, tab: TabType) => {
+      (thread: ThreadInfo, tab: TabType) => {
         if (tab === 'general') {
           return (
             threadHasPermission(thread, threadPermissions.EDIT_THREAD_NAME) ||
diff --git a/web/modals/threads/settings/thread-settings-privacy-tab.react.js b/web/modals/threads/settings/thread-settings-privacy-tab.react.js
--- a/web/modals/threads/settings/thread-settings-privacy-tab.react.js
+++ b/web/modals/threads/settings/thread-settings-privacy-tab.react.js
@@ -12,10 +12,7 @@
 import { type SetState } from 'lib/types/hook-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
-import {
-  type ThreadChanges,
-  type LegacyThreadInfo,
-} from 'lib/types/thread-types.js';
+import { type ThreadChanges } from 'lib/types/thread-types.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 
 import SubmitSection from './submit-section.react.js';
@@ -42,7 +39,7 @@
 
 type ThreadSettingsPrivacyTabProps = {
   +threadSettingsOperationInProgress: boolean,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +queuedChanges: ThreadChanges,
   +setQueuedChanges: SetState<ThreadChanges>,
   +setErrorMessage: SetState<?string>,
diff --git a/web/modals/user-profile/user-profile-action-buttons.react.js b/web/modals/user-profile/user-profile-action-buttons.react.js
--- a/web/modals/user-profile/user-profile-action-buttons.react.js
+++ b/web/modals/user-profile/user-profile-action-buttons.react.js
@@ -6,7 +6,6 @@
 import { useRelationshipPrompt } from 'lib/hooks/relationship-prompt.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { userRelationshipStatus } from 'lib/types/relationship-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types';
 
 import UserProfileMessageButton from './user-profile-message-button.react.js';
 import css from './user-profile.css';
@@ -14,7 +13,7 @@
 import { buttonThemes } from '../../components/button.react.js';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function UserProfileActionButtons(props: Props): React.Node {
diff --git a/web/modals/user-profile/user-profile-menu.react.js b/web/modals/user-profile/user-profile-menu.react.js
--- a/web/modals/user-profile/user-profile-menu.react.js
+++ b/web/modals/user-profile/user-profile-menu.react.js
@@ -8,7 +8,6 @@
 import { useRelationshipPrompt } from 'lib/hooks/relationship-prompt.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import { userRelationshipStatus } from 'lib/types/relationship-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types';
 
 import MenuItem from '../../components/menu-item.react.js';
 import Menu from '../../components/menu.react.js';
@@ -22,7 +21,7 @@
 const unblockIcon = <FontAwesomeIcon icon={faUserShield} />;
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function UserProfileMenu(props: Props): React.Node {
diff --git a/web/modals/user-profile/user-profile-message-button.react.js b/web/modals/user-profile/user-profile-message-button.react.js
--- a/web/modals/user-profile/user-profile-message-button.react.js
+++ b/web/modals/user-profile/user-profile-message-button.react.js
@@ -5,14 +5,13 @@
 import { useModalContext } from 'lib/components/modal-provider.react.js';
 import SWMansionIcon from 'lib/components/SWMansionIcon.react.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './user-profile.css';
 import Button from '../../components/button.react.js';
 import { useOnClickThread } from '../../selectors/thread-selectors.js';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function UserProfileMessageButton(props: Props): React.Node {
diff --git a/web/roles/community-roles-modal.react.js b/web/roles/community-roles-modal.react.js
--- a/web/roles/community-roles-modal.react.js
+++ b/web/roles/community-roles-modal.react.js
@@ -7,7 +7,6 @@
 import { useRoleMemberCountsForCommunity } from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { UserSurfacedPermission } from 'lib/types/thread-permission-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './community-roles-modal.css';
 import CreateRolesModal from './create-roles-modal.react.js';
@@ -17,18 +16,16 @@
 import { useSelector } from '../redux/redux-utils.js';
 
 type CommunityRolesModalProps = {
-  +community: LegacyThreadInfo | ThreadInfo,
+  +community: ThreadInfo,
 };
 
 function CommunityRolesModal(props: CommunityRolesModalProps): React.Node {
   const { popModal, pushModal } = useModalContext();
   const { community } = props;
 
-  const [threadInfo, setThreadInfo] = React.useState<
-    LegacyThreadInfo | ThreadInfo,
-  >(community);
+  const [threadInfo, setThreadInfo] = React.useState<ThreadInfo>(community);
   const threadID = threadInfo.id;
-  const reduxThreadInfo: ?LegacyThreadInfo | ?ThreadInfo = useSelector(
+  const reduxThreadInfo: ?ThreadInfo = useSelector(
     state => threadInfoSelector(state)[threadID],
   );
 
diff --git a/web/roles/create-roles-modal.react.js b/web/roles/create-roles-modal.react.js
--- a/web/roles/create-roles-modal.react.js
+++ b/web/roles/create-roles-modal.react.js
@@ -17,10 +17,7 @@
   type UserSurfacedPermissionOption,
   userSurfacedPermissionOptions,
 } from 'lib/types/thread-permission-types.js';
-import type {
-  LegacyThreadInfo,
-  RoleModificationRequest,
-} from 'lib/types/thread-types.js';
+import type { RoleModificationRequest } from 'lib/types/thread-types.js';
 import { values } from 'lib/utils/objects.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 
@@ -38,7 +35,7 @@
 );
 
 type CreateRolesModalProps = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +action: 'create_role' | 'edit_role',
   +existingRoleID?: string,
   +roleName: string,
diff --git a/web/roles/delete-role-modal.react.js b/web/roles/delete-role-modal.react.js
--- a/web/roles/delete-role-modal.react.js
+++ b/web/roles/delete-role-modal.react.js
@@ -11,7 +11,6 @@
 import { useRoleMemberCountsForCommunity } from 'lib/shared/thread-utils.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
 import { constructRoleDeletionMessagePrompt } from 'lib/utils/role-utils.js';
 
@@ -25,7 +24,7 @@
 );
 
 type DeleteRoleModalProps = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +defaultRoleID: string,
   +roleID: string,
 };
diff --git a/web/roles/role-actions-menu.react.js b/web/roles/role-actions-menu.react.js
--- a/web/roles/role-actions-menu.react.js
+++ b/web/roles/role-actions-menu.react.js
@@ -7,7 +7,6 @@
 import SWMansionIcon from 'lib/components/SWMansionIcon.react.js';
 import { useRoleUserSurfacedPermissions } from 'lib/shared/thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { useRoleDeletableAndEditableStatus } from 'lib/utils/role-utils.js';
 
 import CreateRolesModal from './create-roles-modal.react.js';
@@ -19,7 +18,7 @@
 const menuIcon = <SWMansionIcon icon="menu-horizontal" size={20} />;
 
 type RoleActionsMenuProps = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +roleName: string,
 };
 
diff --git a/web/roles/role-panel-entry.react.js b/web/roles/role-panel-entry.react.js
--- a/web/roles/role-panel-entry.react.js
+++ b/web/roles/role-panel-entry.react.js
@@ -3,14 +3,13 @@
 import * as React from 'react';
 
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import RoleActionsMenu from './role-actions-menu.react.js';
 import css from './role-panel-entry.css';
 import CommIcon from '../CommIcon.react.js';
 
 type RolePanelEntryProps = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
   +roleName: string,
   +memberCount: number,
 };
diff --git a/web/selectors/calendar-selectors.js b/web/selectors/calendar-selectors.js
--- a/web/selectors/calendar-selectors.js
+++ b/web/selectors/calendar-selectors.js
@@ -10,7 +10,6 @@
 import type SearchIndex from 'lib/shared/search-index.js';
 import type { FilterThreadInfo } from 'lib/types/filter-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { filterThreadIDsBelongingToCommunity } from 'lib/utils/drawer-utils.react.js';
 
 import type { AppState } from '../redux/redux-setup.js';
@@ -34,7 +33,7 @@
   (
     calendarPickedCommunityID: ?string,
     threadInfos: {
-      +[id: string]: LegacyThreadInfo | ThreadInfo,
+      +[id: string]: ThreadInfo,
     },
   ) => {
     if (!calendarPickedCommunityID) {
diff --git a/web/selectors/thread-selectors.js b/web/selectors/thread-selectors.js
--- a/web/selectors/thread-selectors.js
+++ b/web/selectors/thread-selectors.js
@@ -16,10 +16,7 @@
   RobotextMessageInfo,
 } from 'lib/types/message-types.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type {
-  LegacyThreadInfo,
-  RawThreadInfos,
-} from 'lib/types/thread-types.js';
+import type { RawThreadInfos } from 'lib/types/thread-types.js';
 import { values } from 'lib/utils/objects.js';
 import { useDispatch } from 'lib/utils/redux-utils.js';
 
@@ -29,7 +26,7 @@
 import { useSelector } from '../redux/redux-utils.js';
 
 function useOnClickThread(
-  thread: ?LegacyThreadInfo | ?ThreadInfo,
+  thread: ?ThreadInfo,
 ): (event: SyntheticEvent<HTMLElement>) => void {
   const dispatch = useDispatch();
   return React.useCallback(
@@ -69,7 +66,7 @@
 
 function useOnClickPendingSidebar(
   messageInfo: ComposableMessageInfo | RobotextMessageInfo,
-  threadInfo: LegacyThreadInfo | ThreadInfo,
+  threadInfo: ThreadInfo,
 ): (event: SyntheticEvent<HTMLElement>) => mixed {
   const dispatch = useDispatch();
   const loggedInUserInfo = useLoggedInUserInfo();
diff --git a/web/sidebar/community-drawer-item-community-handlers.react.js b/web/sidebar/community-drawer-item-community-handlers.react.js
--- a/web/sidebar/community-drawer-item-community-handlers.react.js
+++ b/web/sidebar/community-drawer-item-community-handlers.react.js
@@ -8,7 +8,6 @@
   updateChatCommunityFilter,
 } from 'lib/actions/community-actions.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 import { useDispatch } from 'lib/utils/redux-utils.js';
 
 import type { CommunityDrawerItemCommunityHandler } from './community-drawer-item-handler.react.js';
@@ -22,7 +21,7 @@
 
 export type HandlerProps = {
   +setHandler: (handler: CommunityDrawerItemCommunityHandler) => void,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function ChatDrawerItemCommunityHandler(props: HandlerProps): React.Node {
diff --git a/web/sidebar/community-drawer-item-handlers.react.js b/web/sidebar/community-drawer-item-handlers.react.js
--- a/web/sidebar/community-drawer-item-handlers.react.js
+++ b/web/sidebar/community-drawer-item-handlers.react.js
@@ -3,7 +3,6 @@
 import * as React from 'react';
 
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import type { CommunityDrawerItemHandler } from './community-drawer-item-handler.react.js';
 import { useCommunityIsPickedCalendar } from '../selectors/calendar-selectors.js';
@@ -15,7 +14,7 @@
 
 export type HandlerProps = {
   +setHandler: (handler: CommunityDrawerItemHandler) => void,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function ChatDrawerItemHandler(props: HandlerProps): React.Node {
diff --git a/web/sidebar/community-drawer-utils.react.js b/web/sidebar/community-drawer-utils.react.js
--- a/web/sidebar/community-drawer-utils.react.js
+++ b/web/sidebar/community-drawer-utils.react.js
@@ -3,7 +3,6 @@
 import * as React from 'react';
 
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types';
 import type { CommunityDrawerItemData } from 'lib/utils/drawer-utils.react';
 
 import css from './community-drawer-item.css';
@@ -28,7 +27,7 @@
   hasSubchannelsButton: boolean,
   itemChildren: $ReadOnlyArray<CommunityDrawerItemData<string>>,
   paddingLeft: number,
-  threadInfo: LegacyThreadInfo | ThreadInfo,
+  threadInfo: ThreadInfo,
   expandable: boolean,
   handlerType: NavigationTab,
 }): React.Node {
diff --git a/web/sidebar/subchannels-button.react.js b/web/sidebar/subchannels-button.react.js
--- a/web/sidebar/subchannels-button.react.js
+++ b/web/sidebar/subchannels-button.react.js
@@ -5,14 +5,13 @@
 
 import { useModalContext } from 'lib/components/modal-provider.react.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './subchannels-button.css';
 import Button from '../components/button.react.js';
 import SubchannelsModal from '../modals/threads/subchannels/subchannels-modal.react.js';
 
 type Props = {
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 
 function SubchannelsButton(props: Props): React.Node {
diff --git a/web/tooltips/message-tooltip.react.js b/web/tooltips/message-tooltip.react.js
--- a/web/tooltips/message-tooltip.react.js
+++ b/web/tooltips/message-tooltip.react.js
@@ -8,7 +8,6 @@
 import type { ChatMessageInfoItem } from 'lib/selectors/chat-selectors.js';
 import { useNextLocalID } from 'lib/shared/message-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import type { LegacyThreadInfo } from 'lib/types/thread-types.js';
 
 import css from './message-tooltip.css';
 import {
@@ -33,7 +32,7 @@
   +tooltipPositionStyle: TooltipPositionStyle,
   +tooltipSize: TooltipSize,
   +item: ChatMessageInfoItem,
-  +threadInfo: LegacyThreadInfo | ThreadInfo,
+  +threadInfo: ThreadInfo,
 };
 function MessageTooltip(props: MessageTooltipProps): React.Node {
   const {