diff --git a/keyserver/src/creators/role-creator.js b/keyserver/src/creators/role-creator.js
--- a/keyserver/src/creators/role-creator.js
+++ b/keyserver/src/creators/role-creator.js
@@ -9,14 +9,12 @@
   getThreadPermissionBlobFromUserSurfacedPermissions,
 } from 'lib/permissions/thread-permissions.js';
 import { threadHasPermission } from 'lib/shared/thread-utils.js';
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import {
   userSurfacedPermissionsSet,
   threadPermissions,
 } from 'lib/types/thread-permission-types.js';
-import {
-  threadTypeIsCommunityRoot,
-  type ThreadType,
-} from 'lib/types/thread-types-enum.js';
+import { type ThreadType } from 'lib/types/thread-types-enum.js';
 import type {
   RoleModificationRequest,
   RoleModificationResult,
diff --git a/keyserver/src/creators/thread-creator.js b/keyserver/src/creators/thread-creator.js
--- a/keyserver/src/creators/thread-creator.js
+++ b/keyserver/src/creators/thread-creator.js
@@ -10,13 +10,11 @@
 } from 'lib/shared/color-utils.js';
 import { isInvalidSidebarSource } from 'lib/shared/message-utils.js';
 import { getThreadTypeParentRequirement } from 'lib/shared/thread-utils.js';
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import { messageTypes } from 'lib/types/message-types-enum.js';
 import type { RawMessageInfo, MessageData } from 'lib/types/message-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import {
-  threadTypes,
-  threadTypeIsCommunityRoot,
-} from 'lib/types/thread-types-enum.js';
+import { threadTypes } from 'lib/types/thread-types-enum.js';
 import {
   type ServerNewThinThreadRequest,
   type NewThreadResponse,
diff --git a/keyserver/src/fetchers/user-fetchers.js b/keyserver/src/fetchers/user-fetchers.js
--- a/keyserver/src/fetchers/user-fetchers.js
+++ b/keyserver/src/fetchers/user-fetchers.js
@@ -2,6 +2,7 @@
 
 import invariant from 'invariant';
 
+import { communityThreadTypes } from 'lib/shared/threads/thread-specs.js';
 import {
   hasMinCodeVersion,
   FUTURE_CODE_VERSION,
@@ -13,7 +14,6 @@
   userRelationshipStatus,
 } from 'lib/types/relationship-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import { communityThreadTypes } from 'lib/types/thread-types-enum.js';
 import type {
   UserInfos,
   CurrentUserInfo,
diff --git a/keyserver/src/updaters/role-updaters.js b/keyserver/src/updaters/role-updaters.js
--- a/keyserver/src/updaters/role-updaters.js
+++ b/keyserver/src/updaters/role-updaters.js
@@ -8,9 +8,9 @@
   getRolePermissionBlobs,
   getThreadPermissionBlobFromUserSurfacedPermissions,
 } from 'lib/permissions/thread-permissions.js';
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import {
   type ThinThreadType,
-  threadTypeIsCommunityRoot,
   threadTypes,
 } from 'lib/types/thread-types-enum.js';
 import type { ServerLegacyRoleInfo } from 'lib/types/thread-types.js';
diff --git a/lib/components/sync-community-store-handler.react.js b/lib/components/sync-community-store-handler.react.js
--- a/lib/components/sync-community-store-handler.react.js
+++ b/lib/components/sync-community-store-handler.react.js
@@ -7,7 +7,7 @@
   fetchCommunityInfosActionTypes,
 } from '../actions/community-actions.js';
 import { isLoggedIn } from '../selectors/user-selectors.js';
-import { threadTypeIsCommunityRoot } from '../types/thread-types-enum.js';
+import { threadTypeIsCommunityRoot } from '../shared/threads/thread-specs.js';
 import { FetchTimeout } from '../utils/errors.js';
 import { useDispatchActionPromise } from '../utils/redux-promise-utils.js';
 import { useSelector } from '../utils/redux-utils.js';
diff --git a/lib/hooks/sidebar-hooks.js b/lib/hooks/sidebar-hooks.js
--- a/lib/hooks/sidebar-hooks.js
+++ b/lib/hooks/sidebar-hooks.js
@@ -7,7 +7,7 @@
 import { childThreadInfos } from '../selectors/thread-selectors.js';
 import { getMostRecentNonLocalMessageID } from '../shared/message-utils.js';
 import { threadInChatList } from '../shared/thread-utils.js';
-import { threadTypeIsSidebar } from '../types/thread-types-enum.js';
+import { threadTypeIsSidebar } from '../shared/threads/thread-specs.js';
 import type { SidebarInfo } from '../types/thread-types.js';
 import { useSelector } from '../utils/redux-utils.js';
 
diff --git a/lib/permissions/add-users-permissions.js b/lib/permissions/add-users-permissions.js
--- a/lib/permissions/add-users-permissions.js
+++ b/lib/permissions/add-users-permissions.js
@@ -2,10 +2,10 @@
 
 import { primaryInviteLinksSelector } from '../selectors/invite-links-selectors.js';
 import { useThreadHasPermission } from '../shared/thread-utils.js';
+import { threadTypeIsCommunityRoot } from '../shared/threads/thread-specs.js';
 import type { InviteLink } from '../types/link-types.js';
 import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from '../types/thread-permission-types.js';
-import { threadTypeIsCommunityRoot } from '../types/thread-types-enum.js';
 import { useSelector } from '../utils/redux-utils.js';
 
 type AddUsersPermissions = {
diff --git a/lib/permissions/prefixes.js b/lib/permissions/prefixes.js
--- a/lib/permissions/prefixes.js
+++ b/lib/permissions/prefixes.js
@@ -1,5 +1,6 @@
 // @flow
 
+import { threadTypeIsSidebar } from '../shared/threads/thread-specs.js';
 import {
   type ThreadPermission,
   type ThreadPermissionFilterPrefix,
@@ -10,11 +11,7 @@
   threadPermissionPropagationPrefixes,
   threadPermissionMembershipPrefixes,
 } from '../types/thread-permission-types.js';
-import {
-  threadTypes,
-  type ThreadType,
-  threadTypeIsSidebar,
-} from '../types/thread-types-enum.js';
+import { threadTypes, type ThreadType } from '../types/thread-types-enum.js';
 
 type ParsedThreadPermissionString = {
   +permission: ThreadPermission,
diff --git a/lib/permissions/thread-permissions.js b/lib/permissions/thread-permissions.js
--- a/lib/permissions/thread-permissions.js
+++ b/lib/permissions/thread-permissions.js
@@ -7,6 +7,10 @@
   constructThreadPermissionString,
   includeThreadPermissionForThreadType,
 } from './prefixes.js';
+import {
+  threadTypeIsAnnouncementThread,
+  threadTypeIsCommunityRoot,
+} from '../shared/threads/thread-specs.js';
 import {
   configurableCommunityPermissions,
   threadPermissionFilterPrefixes,
@@ -29,11 +33,9 @@
   type ThinThreadType,
   type ThickThreadType,
   threadTypes,
-  threadTypeIsAnnouncementThread,
   threadTypeIsThick,
   assertThickThreadType,
   assertThinThreadType,
-  threadTypeIsCommunityRoot,
 } from '../types/thread-types-enum.js';
 
 function permissionLookup(
diff --git a/lib/selectors/chat-selectors.js b/lib/selectors/chat-selectors.js
--- a/lib/selectors/chat-selectors.js
+++ b/lib/selectors/chat-selectors.js
@@ -27,6 +27,7 @@
   type SidebarItem,
 } from '../shared/sidebar-item-utils.js';
 import { threadInChatList, threadIsPending } from '../shared/thread-utils.js';
+import { threadTypeIsSidebar } from '../shared/threads/thread-specs.js';
 import { messageTypes } from '../types/message-types-enum.js';
 import {
   type ComposableMessageInfo,
@@ -41,7 +42,6 @@
   RawThreadInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import type { BaseAppState } from '../types/redux-types.js';
-import { threadTypeIsSidebar } from '../types/thread-types-enum.js';
 import type {
   AccountUserInfo,
   RelativeUserInfo,
diff --git a/lib/selectors/nav-selectors.js b/lib/selectors/nav-selectors.js
--- a/lib/selectors/nav-selectors.js
+++ b/lib/selectors/nav-selectors.js
@@ -5,6 +5,7 @@
 
 import { useENSNames } from '../hooks/ens-cache.js';
 import SearchIndex from '../shared/search-index.js';
+import { threadTypeIsPrivate } from '../shared/threads/thread-specs.js';
 import type { Platform } from '../types/device-types.js';
 import {
   type CalendarQuery,
@@ -18,7 +19,6 @@
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import type { BaseNavInfo } from '../types/nav-types.js';
 import type { BaseAppState } from '../types/redux-types.js';
-import { threadTypeIsPrivate } from '../types/thread-types-enum.js';
 import type { UserInfo } from '../types/user-types.js';
 import { getConfig } from '../utils/config.js';
 import { useSelector } from '../utils/redux-utils.js';
diff --git a/lib/selectors/thread-selectors.js b/lib/selectors/thread-selectors.js
--- a/lib/selectors/thread-selectors.js
+++ b/lib/selectors/thread-selectors.js
@@ -34,6 +34,15 @@
   threadIsPending,
   getPendingThreadID,
 } from '../shared/thread-utils.js';
+import {
+  personalThreadTypes,
+  privateThreadTypes,
+  sidebarThreadTypes,
+  threadTypeIsCommunityRoot,
+  threadTypeIsPersonal,
+  threadTypeIsPrivate,
+  threadTypeIsSidebar,
+} from '../shared/threads/thread-specs.js';
 import type { ClientAvatar, ClientEmojiAvatar } from '../types/avatar-types';
 import type { EntryInfo } from '../types/entry-types.js';
 import type { MessageStore } from '../types/message-types.js';
@@ -46,15 +55,8 @@
 import type { BaseAppState } from '../types/redux-types.js';
 import {
   threadTypeIsThick,
-  threadTypeIsCommunityRoot,
   type ThreadType,
   threadTypes,
-  threadTypeIsSidebar,
-  threadTypeIsPrivate,
-  threadTypeIsPersonal,
-  personalThreadTypes,
-  privateThreadTypes,
-  sidebarThreadTypes,
 } from '../types/thread-types-enum.js';
 import type {
   MixedRawThreadInfos,
diff --git a/lib/selectors/user-selectors.js b/lib/selectors/user-selectors.js
--- a/lib/selectors/user-selectors.js
+++ b/lib/selectors/user-selectors.js
@@ -9,6 +9,7 @@
   getRandomDefaultEmojiAvatar,
 } from '../shared/avatar-utils.js';
 import { getSingleOtherUser } from '../shared/thread-utils.js';
+import { threadTypeIsPersonal } from '../shared/threads/thread-specs.js';
 import { type P2PMessageRecipient } from '../tunnelbroker/peer-to-peer-context.js';
 import {
   type AuxUserInfos,
@@ -26,7 +27,6 @@
 } from '../types/minimally-encoded-thread-permissions-types.js';
 import type { BaseAppState } from '../types/redux-types.js';
 import { userRelationshipStatus } from '../types/relationship-types.js';
-import { threadTypeIsPersonal } from '../types/thread-types-enum.js';
 import type { RawThreadInfos } from '../types/thread-types.js';
 import type {
   UserInfos,
diff --git a/lib/shared/avatar-utils.js b/lib/shared/avatar-utils.js
--- a/lib/shared/avatar-utils.js
+++ b/lib/shared/avatar-utils.js
@@ -7,6 +7,10 @@
 import { getETHAddressForUserInfo } from './account-utils.js';
 import { selectedThreadColors } from './color-utils.js';
 import { threadOtherMembers } from './thread-utils.js';
+import {
+  threadTypeIsPersonal,
+  threadTypeIsPrivate,
+} from './threads/thread-specs.js';
 import genesis from '../facts/genesis.js';
 import { useENSAvatar } from '../hooks/ens-cache.js';
 import {
@@ -22,10 +26,6 @@
   ThreadInfo,
   RawThreadInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
-import {
-  threadTypeIsPersonal,
-  threadTypeIsPrivate,
-} from '../types/thread-types-enum.js';
 import type { UserInfos } from '../types/user-types.js';
 
 const defaultAnonymousUserEmojiAvatar: ClientEmojiAvatar = {
diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -4,6 +4,7 @@
 
 import { markdownUserMentionRegexString } from './account-utils.js';
 import SentencePrefixSearchIndex from './sentence-prefix-search-index.js';
+import { threadTypeIsSidebar } from './threads/thread-specs.js';
 import { stringForUserExplicit } from './user-utils.js';
 import { useENSNames } from '../hooks/ens-cache.js';
 import { useUserSearchIndex } from '../selectors/nav-selectors.js';
@@ -12,7 +13,6 @@
   ResolvedThreadInfo,
   ThreadInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
-import { threadTypeIsSidebar } from '../types/thread-types-enum.js';
 import type { ChatMentionCandidates } from '../types/thread-types.js';
 import { chatNameMaxLength, idSchemaRegex } from '../utils/validation-utils.js';
 
diff --git a/lib/shared/messages/create-sub-thread-message-spec.js b/lib/shared/messages/create-sub-thread-message-spec.js
--- a/lib/shared/messages/create-sub-thread-message-spec.js
+++ b/lib/shared/messages/create-sub-thread-message-spec.js
@@ -24,10 +24,10 @@
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
 import { threadPermissions } from '../../types/thread-permission-types.js';
-import { threadTypeIsSidebar } from '../../types/thread-types-enum.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import { type EntityText, ET } from '../../utils/entity-text.js';
 import { notifTextsForSubthreadCreation } from '../notif-utils.js';
+import { threadTypeIsSidebar } from '../threads/thread-specs.js';
 
 type CreateSubThreadMessageSpec = MessageSpec<
   CreateSubthreadMessageData,
diff --git a/lib/shared/messages/text-message-spec.js b/lib/shared/messages/text-message-spec.js
--- a/lib/shared/messages/text-message-spec.js
+++ b/lib/shared/messages/text-message-spec.js
@@ -28,10 +28,7 @@
 } from '../../types/messages/text.js';
 import type { ThreadInfo } from '../../types/minimally-encoded-thread-permissions-types.js';
 import type { NotifTexts } from '../../types/notif-types.js';
-import {
-  threadTypeIsSidebar,
-  threadTypeIsThick,
-} from '../../types/thread-types-enum.js';
+import { threadTypeIsThick } from '../../types/thread-types-enum.js';
 import type { RelativeUserInfo } from '../../types/user-types.js';
 import { ET } from '../../utils/entity-text.js';
 import { useDispatchActionPromise } from '../../utils/redux-promise-utils.js';
@@ -51,6 +48,7 @@
   extractNewMentionedParentMembers,
   threadIsGroupChat,
 } from '../thread-utils.js';
+import { threadTypeIsSidebar } from '../threads/thread-specs.js';
 
 /**
  * most of the markdown leaves contain `content` field
diff --git a/lib/shared/search-utils.js b/lib/shared/search-utils.js
--- a/lib/shared/search-utils.js
+++ b/lib/shared/search-utils.js
@@ -9,6 +9,7 @@
   userIsMember,
   userHasDeviceList,
 } from './thread-utils.js';
+import { threadTypeIsSidebar } from './threads/thread-specs.js';
 import {
   searchMessagesActionTypes,
   useSearchMessages as useSearchMessagesAction,
@@ -40,7 +41,6 @@
 import type { ThreadRolePermissionsBlob } from '../types/thread-permission-types.js';
 import {
   type ThreadType,
-  threadTypeIsSidebar,
   threadTypeIsThick,
 } from '../types/thread-types-enum.js';
 import type {
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
@@ -12,6 +12,7 @@
   useThreadHasPermission,
   userIsMember,
 } from './thread-utils.js';
+import { 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';
@@ -21,11 +22,7 @@
 } from '../types/message-types.js';
 import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
 import { threadPermissions } from '../types/thread-permission-types.js';
-import {
-  threadTypes,
-  threadTypeIsThick,
-  threadTypeIsPersonal,
-} from '../types/thread-types-enum.js';
+import { threadTypes, threadTypeIsThick } from '../types/thread-types-enum.js';
 import type { LoggedInUserInfo } from '../types/user-types.js';
 import type { GetENSNames } from '../utils/ens-helpers.js';
 import {
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
@@ -13,6 +13,12 @@
 import { extractUserMentionsFromText } from './mention-utils.js';
 import { relationshipBlockedInEitherDirection } from './relationship-utils.js';
 import type { SidebarItem } from './sidebar-item-utils.js';
+import {
+  threadTypeIsCommunityRoot,
+  threadTypeIsPersonal,
+  threadTypeIsPrivate,
+  threadTypeIsSidebar,
+} from './threads/thread-specs.js';
 import ashoat from '../facts/ashoat.js';
 import genesis from '../facts/genesis.js';
 import { useLoggedInUserInfo } from '../hooks/account-hooks.js';
@@ -76,14 +82,10 @@
 import {
   type ThreadType,
   threadTypes,
-  threadTypeIsCommunityRoot,
   assertThreadType,
   threadTypeIsThick,
   assertThinThreadType,
   assertThickThreadType,
-  threadTypeIsSidebar,
-  threadTypeIsPrivate,
-  threadTypeIsPersonal,
   type ThinThreadType,
 } from '../types/thread-types-enum.js';
 import type {
diff --git a/lib/shared/threads/community-announcement-root-spec.js b/lib/shared/threads/community-announcement-root-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-announcement-root-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communityAnnouncementRootSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['community', 'announcement']),
+});
+
+export { communityAnnouncementRootSpec };
diff --git a/lib/shared/threads/community-open-announcement-subthread-spec.js b/lib/shared/threads/community-open-announcement-subthread-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-open-announcement-subthread-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communityOpenAnnouncementSubthreadSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['communitySubthread', 'announcement']),
+});
+
+export { communityOpenAnnouncementSubthreadSpec };
diff --git a/lib/shared/threads/community-open-subthread-spec.js b/lib/shared/threads/community-open-subthread-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-open-subthread-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communityOpenSubthreadSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['communitySubthread']),
+});
+
+export { communityOpenSubthreadSpec };
diff --git a/lib/shared/threads/community-root-spec.js b/lib/shared/threads/community-root-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-root-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communityRootSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['community']),
+});
+
+export { communityRootSpec };
diff --git a/lib/shared/threads/community-secret-announcement-subthread-spec.js b/lib/shared/threads/community-secret-announcement-subthread-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-secret-announcement-subthread-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communitySecretAnnouncementSubthreadSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['communitySubthread', 'announcement']),
+});
+
+export { communitySecretAnnouncementSubthreadSpec };
diff --git a/lib/shared/threads/community-secret-subthread-spec.js b/lib/shared/threads/community-secret-subthread-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/community-secret-subthread-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const communitySecretSubthreadSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['communitySubthread']),
+});
+
+export { communitySecretSubthreadSpec };
diff --git a/lib/shared/threads/genesis-personal-spec.js b/lib/shared/threads/genesis-personal-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/genesis-personal-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const genesisPersonalSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['personal']),
+});
+
+export { genesisPersonalSpec };
diff --git a/lib/shared/threads/genesis-private-spec.js b/lib/shared/threads/genesis-private-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/genesis-private-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const genesisPrivateSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['private']),
+});
+
+export { genesisPrivateSpec };
diff --git a/lib/shared/threads/genesis-spec.js b/lib/shared/threads/genesis-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/genesis-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const genesisSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['community', 'announcement']),
+});
+
+export { genesisSpec };
diff --git a/lib/shared/threads/local-spec.js b/lib/shared/threads/local-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/local-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const localSpec: ThreadSpec = Object.freeze({
+  traits: new Set(),
+});
+
+export { localSpec };
diff --git a/lib/shared/threads/personal-spec.js b/lib/shared/threads/personal-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/personal-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const personalSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['personal']),
+});
+
+export { personalSpec };
diff --git a/lib/shared/threads/private-spec.js b/lib/shared/threads/private-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/private-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const privateSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['private']),
+});
+
+export { privateSpec };
diff --git a/lib/shared/threads/sidebar-spec.js b/lib/shared/threads/sidebar-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/sidebar-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const sidebarSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['sidebar']),
+});
+
+export { sidebarSpec };
diff --git a/lib/shared/threads/thick-sidebar-spec.js b/lib/shared/threads/thick-sidebar-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/thick-sidebar-spec.js
@@ -0,0 +1,9 @@
+// @flow
+
+import type { ThreadSpec } from './thread-spec.js';
+
+const thickSidebarSpec: ThreadSpec = Object.freeze({
+  traits: new Set(['sidebar']),
+});
+
+export { thickSidebarSpec };
diff --git a/lib/shared/threads/thread-spec.js b/lib/shared/threads/thread-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/thread-spec.js
@@ -0,0 +1,13 @@
+// @flow
+
+export type ThreadTrait =
+  | 'sidebar'
+  | 'community'
+  | 'announcement'
+  | 'personal'
+  | 'private'
+  | 'communitySubthread';
+
+export type ThreadSpec = {
+  +traits: $ReadOnlySet<ThreadTrait>,
+};
diff --git a/lib/shared/threads/thread-specs.js b/lib/shared/threads/thread-specs.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/threads/thread-specs.js
@@ -0,0 +1,95 @@
+// @flow
+
+import { communityAnnouncementRootSpec } from './community-announcement-root-spec.js';
+import { communityOpenAnnouncementSubthreadSpec } from './community-open-announcement-subthread-spec.js';
+import { communityOpenSubthreadSpec } from './community-open-subthread-spec.js';
+import { communityRootSpec } from './community-root-spec.js';
+import { communitySecretAnnouncementSubthreadSpec } from './community-secret-announcement-subthread-spec.js';
+import { communitySecretSubthreadSpec } from './community-secret-subthread-spec.js';
+import { genesisPersonalSpec } from './genesis-personal-spec.js';
+import { genesisPrivateSpec } from './genesis-private-spec.js';
+import { genesisSpec } from './genesis-spec.js';
+import { localSpec } from './local-spec.js';
+import { personalSpec } from './personal-spec.js';
+import { privateSpec } from './private-spec.js';
+import { sidebarSpec } from './sidebar-spec.js';
+import { thickSidebarSpec } from './thick-sidebar-spec.js';
+import type { ThreadSpec, ThreadTrait } from './thread-spec.js';
+import type { ThreadType } from '../../types/thread-types-enum.js';
+import { threadTypes } from '../../types/thread-types-enum.js';
+import { values } from '../../utils/objects.js';
+
+export const threadSpecs: {
+  +[ThreadType]: ThreadSpec,
+} = Object.freeze({
+  [threadTypes.SIDEBAR]: sidebarSpec,
+  [threadTypes.GENESIS_PERSONAL]: genesisPersonalSpec,
+  [threadTypes.GENESIS_PRIVATE]: genesisPrivateSpec,
+  [threadTypes.COMMUNITY_ROOT]: communityRootSpec,
+  [threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT]: communityAnnouncementRootSpec,
+  [threadTypes.COMMUNITY_OPEN_SUBTHREAD]: communityOpenSubthreadSpec,
+  [threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD]:
+    communityOpenAnnouncementSubthreadSpec,
+  [threadTypes.COMMUNITY_SECRET_SUBTHREAD]: communitySecretSubthreadSpec,
+  [threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD]:
+    communitySecretAnnouncementSubthreadSpec,
+  [threadTypes.GENESIS]: genesisSpec,
+  [threadTypes.LOCAL]: localSpec,
+  [threadTypes.PERSONAL]: personalSpec,
+  [threadTypes.PRIVATE]: privateSpec,
+  [threadTypes.THICK_SIDEBAR]: thickSidebarSpec,
+});
+
+let threadTypesByTrait = null;
+export function getThreadTypesByTrait(
+  trait: ThreadTrait,
+): $ReadOnlyArray<ThreadType> {
+  if (!threadTypesByTrait) {
+    const threadTypesByTraitMutable: { [ThreadTrait]: Array<ThreadType> } = {};
+    for (const threadType of values(threadTypes)) {
+      for (const threadTraits of threadSpecs[threadType].traits) {
+        if (!threadTypesByTraitMutable[threadTraits]) {
+          threadTypesByTraitMutable[threadTraits] = [];
+        }
+        threadTypesByTraitMutable[threadTraits].push(threadType);
+      }
+    }
+    threadTypesByTrait = threadTypesByTraitMutable;
+  }
+  return threadTypesByTrait[trait];
+}
+
+export const communitySubthreads: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('communitySubthread');
+
+export const communityThreadTypes: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('community');
+export function threadTypeIsCommunityRoot(threadType: ThreadType): boolean {
+  return communityThreadTypes.includes(threadType);
+}
+
+export const announcementThreadTypes: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('announcement');
+export function threadTypeIsAnnouncementThread(
+  threadType: ThreadType,
+): boolean {
+  return announcementThreadTypes.includes(threadType);
+}
+
+export const sidebarThreadTypes: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('sidebar');
+export function threadTypeIsSidebar(threadType: ThreadType): boolean {
+  return sidebarThreadTypes.includes(threadType);
+}
+
+export const personalThreadTypes: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('personal');
+export function threadTypeIsPersonal(threadType: ThreadType): boolean {
+  return personalThreadTypes.includes(threadType);
+}
+
+export const privateThreadTypes: $ReadOnlyArray<ThreadType> =
+  getThreadTypesByTrait('private');
+export function threadTypeIsPrivate(threadType: ThreadType): boolean {
+  return privateThreadTypes.includes(threadType);
+}
diff --git a/lib/types/thread-types-enum.js b/lib/types/thread-types-enum.js
--- a/lib/types/thread-types-enum.js
+++ b/lib/types/thread-types-enum.js
@@ -139,63 +139,3 @@
 export const threadTypeValidator: TRefinement<number> = tNumEnum(
   values(threadTypes),
 );
-
-export const communityThreadTypes: $ReadOnlyArray<ThinThreadType> =
-  Object.freeze([
-    threadTypes.COMMUNITY_ROOT,
-    threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT,
-    threadTypes.GENESIS,
-  ]);
-
-export const announcementThreadTypes: $ReadOnlyArray<ThinThreadType> =
-  Object.freeze([
-    threadTypes.GENESIS,
-    threadTypes.COMMUNITY_ANNOUNCEMENT_ROOT,
-    threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD,
-    threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD,
-  ]);
-
-export const communitySubthreads: $ReadOnlyArray<ThinThreadType> =
-  Object.freeze([
-    threadTypes.COMMUNITY_OPEN_SUBTHREAD,
-    threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD,
-    threadTypes.COMMUNITY_SECRET_SUBTHREAD,
-    threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD,
-  ]);
-
-export const sidebarThreadTypes: $ReadOnlyArray<ThreadType> = Object.freeze([
-  threadTypes.SIDEBAR,
-  threadTypes.THICK_SIDEBAR,
-]);
-
-export const personalThreadTypes: $ReadOnlyArray<ThreadType> = Object.freeze([
-  threadTypes.PERSONAL,
-  threadTypes.GENESIS_PERSONAL,
-]);
-
-export const privateThreadTypes: $ReadOnlyArray<ThreadType> = Object.freeze([
-  threadTypes.PRIVATE,
-  threadTypes.GENESIS_PRIVATE,
-]);
-
-export function threadTypeIsCommunityRoot(threadType: ThreadType): boolean {
-  return communityThreadTypes.includes(threadType);
-}
-
-export function threadTypeIsAnnouncementThread(
-  threadType: ThreadType,
-): boolean {
-  return announcementThreadTypes.includes(threadType);
-}
-
-export function threadTypeIsSidebar(threadType: ThreadType): boolean {
-  return sidebarThreadTypes.includes(threadType);
-}
-
-export function threadTypeIsPersonal(threadType: ThreadType): boolean {
-  return personalThreadTypes.includes(threadType);
-}
-
-export function threadTypeIsPrivate(threadType: ThreadType): boolean {
-  return privateThreadTypes.includes(threadType);
-}
diff --git a/lib/utils/drawer-utils.react.js b/lib/utils/drawer-utils.react.js
--- a/lib/utils/drawer-utils.react.js
+++ b/lib/utils/drawer-utils.react.js
@@ -4,12 +4,12 @@
 
 import { values } from './objects.js';
 import { threadInFilterList, threadIsChannel } from '../shared/thread-utils.js';
+import { communitySubthreads } from '../shared/threads/thread-specs.js';
 import type {
   ResolvedThreadInfo,
   ThreadInfo,
   RawThreadInfo,
 } from '../types/minimally-encoded-thread-permissions-types.js';
-import { communitySubthreads } from '../types/thread-types-enum.js';
 
 type WritableCommunityDrawerItemData<T> = {
   threadInfo: ResolvedThreadInfo,
diff --git a/native/avatars/thread-avatar.react.js b/native/avatars/thread-avatar.react.js
--- a/native/avatars/thread-avatar.react.js
+++ b/native/avatars/thread-avatar.react.js
@@ -5,6 +5,10 @@
 import { useAvatarForThread } from 'lib/hooks/avatar-hooks.js';
 import { useResolvedThreadAvatar } from 'lib/shared/avatar-utils.js';
 import { getSingleOtherUser, getCommunity } from 'lib/shared/thread-utils.js';
+import {
+  threadTypeIsPersonal,
+  threadTypeIsPrivate,
+} from 'lib/shared/threads/thread-specs.js';
 import type { AvatarSize } from 'lib/types/avatar-types.js';
 import type { CommunityInfo } from 'lib/types/community-types.js';
 import type {
@@ -12,10 +16,6 @@
   ResolvedThreadInfo,
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import {
-  threadTypeIsPersonal,
-  threadTypeIsPrivate,
-} from 'lib/types/thread-types-enum.js';
 
 import Avatar from './avatar.react.js';
 import { useSelector } from '../redux/redux-utils.js';
diff --git a/native/chat/message-list.react.js b/native/chat/message-list.react.js
--- a/native/chat/message-list.react.js
+++ b/native/chat/message-list.react.js
@@ -8,9 +8,9 @@
 
 import { chatMessageItemKey } from 'lib/shared/chat-message-item-utils.js';
 import { useFetchMessages } from 'lib/shared/message-utils.js';
+import { threadTypeIsPersonal } from 'lib/shared/threads/thread-specs.js';
 import { useWatchThread } from 'lib/shared/watch-thread-utils.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import { threadTypeIsPersonal } from 'lib/types/thread-types-enum.js';
 
 import ChatList from './chat-list.react.js';
 import type { ChatNavigationProp } from './chat.react.js';
diff --git a/native/chat/settings/thread-settings.react.js b/native/chat/settings/thread-settings.react.js
--- a/native/chat/settings/thread-settings.react.js
+++ b/native/chat/settings/thread-settings.react.js
@@ -38,6 +38,10 @@
   viewerIsMember,
 } from 'lib/shared/thread-utils.js';
 import threadWatcher from 'lib/shared/thread-watcher.js';
+import {
+  threadTypeIsPersonal,
+  threadTypeIsSidebar,
+} from 'lib/shared/threads/thread-specs.js';
 import type {
   RelativeMemberInfo,
   ResolvedThreadInfo,
@@ -45,11 +49,7 @@
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { RelationshipButton } from 'lib/types/relationship-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import {
-  threadTypeIsSidebar,
-  threadTypeIsThick,
-  threadTypeIsPersonal,
-} from 'lib/types/thread-types-enum.js';
+import { threadTypeIsThick } from 'lib/types/thread-types-enum.js';
 import type { UserInfos } from 'lib/types/user-types.js';
 import {
   useResolvedOptionalThreadInfo,
diff --git a/native/components/thread-icon.react.js b/native/components/thread-icon.react.js
--- a/native/components/thread-icon.react.js
+++ b/native/components/thread-icon.react.js
@@ -4,11 +4,8 @@
 import * as React from 'react';
 import { StyleSheet } from 'react-native';
 
-import {
-  threadTypes,
-  type ThreadType,
-  threadTypeIsSidebar,
-} from 'lib/types/thread-types-enum.js';
+import { threadTypeIsSidebar } from 'lib/shared/threads/thread-specs.js';
+import { threadTypes, type ThreadType } from 'lib/types/thread-types-enum.js';
 
 import SWMansionIcon from './swmansion-icon.react.js';
 
diff --git a/native/input/input-state-container.react.js b/native/input/input-state-container.react.js
--- a/native/input/input-state-container.react.js
+++ b/native/input/input-state-container.react.js
@@ -52,6 +52,7 @@
   threadIsPending,
   threadIsPendingSidebar,
 } from 'lib/shared/thread-utils.js';
+import { threadTypeIsSidebar } from 'lib/shared/threads/thread-specs.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 import type {
   Media,
@@ -77,9 +78,8 @@
 } from 'lib/types/report-types.js';
 import {
   threadTypeIsThick,
-  threadTypeIsSidebar,
+  type ThreadType,
 } from 'lib/types/thread-types-enum.js';
-import type { ThreadType } from 'lib/types/thread-types-enum.js';
 import {
   type ClientNewThinThreadRequest,
   type NewThreadResult,
diff --git a/native/navigation/community-drawer-content.react.js b/native/navigation/community-drawer-content.react.js
--- a/native/navigation/community-drawer-content.react.js
+++ b/native/navigation/community-drawer-content.react.js
@@ -18,11 +18,11 @@
 import { useLegacyAshoatKeyserverCall } from 'lib/keyserver-conn/legacy-keyserver-call.js';
 import { communityThreadSelector } from 'lib/selectors/thread-selectors.js';
 import { viewerIsMember } from 'lib/shared/thread-utils.js';
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import type {
   ClientCommunityInfoWithCommunityName,
   ClientFetchNativeDrawerAndDirectoryInfosResponse,
 } from 'lib/types/community-types.js';
-import { threadTypeIsCommunityRoot } from 'lib/types/thread-types-enum.js';
 import {
   createRecursiveDrawerItemsData,
   useAppendCommunitySuffix,
diff --git a/native/navigation/community-drawer-item.react.js b/native/navigation/community-drawer-item.react.js
--- a/native/navigation/community-drawer-item.react.js
+++ b/native/navigation/community-drawer-item.react.js
@@ -3,7 +3,7 @@
 import * as React from 'react';
 import { View, TouchableOpacity } from 'react-native';
 
-import { threadTypeIsCommunityRoot } from 'lib/types/thread-types-enum.js';
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import { useResolvedThreadInfo } from 'lib/utils/entity-helpers.js';
 
 import { ExpandButton, ExpandButtonDisabled } from './expand-buttons.react.js';
diff --git a/native/utils/drawer-utils.react.js b/native/utils/drawer-utils.react.js
--- a/native/utils/drawer-utils.react.js
+++ b/native/utils/drawer-utils.react.js
@@ -1,7 +1,7 @@
 // @flow
 
+import { threadTypeIsCommunityRoot } from 'lib/shared/threads/thread-specs.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import { threadTypeIsCommunityRoot } from 'lib/types/thread-types-enum.js';
 import type { CommunityDrawerItemData } from 'lib/utils/drawer-utils.react.js';
 
 import type { TextStyle } from '../types/styles.js';
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
@@ -5,16 +5,16 @@
 import { useAvatarForThread } from 'lib/hooks/avatar-hooks.js';
 import { useResolvedThreadAvatar } from 'lib/shared/avatar-utils.js';
 import { getSingleOtherUser, getCommunity } from 'lib/shared/thread-utils.js';
+import {
+  threadTypeIsPersonal,
+  threadTypeIsPrivate,
+} from 'lib/shared/threads/thread-specs.js';
 import type { AvatarSize } from 'lib/types/avatar-types.js';
 import type { CommunityInfo } from 'lib/types/community-types.js';
 import type {
   ThreadInfo,
   RawThreadInfo,
 } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import {
-  threadTypeIsPersonal,
-  threadTypeIsPrivate,
-} from 'lib/types/thread-types-enum.js';
 
 import Avatar from './avatar.react.js';
 import { useSelector } from '../redux/redux-utils.js';
diff --git a/web/chat/chat-message-list.react.js b/web/chat/chat-message-list.react.js
--- a/web/chat/chat-message-list.react.js
+++ b/web/chat/chat-message-list.react.js
@@ -17,8 +17,8 @@
   threadIsPending,
   threadOtherMembers,
 } from 'lib/shared/thread-utils.js';
+import { threadTypeIsPersonal } from 'lib/shared/threads/thread-specs.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import { threadTypeIsPersonal } from 'lib/types/thread-types-enum.js';
 
 import { defaultMaxTextAreaHeight, editBoxHeight } from './chat-constants.js';
 import css from './chat-message-list.css';
diff --git a/web/chat/thread-list-provider.js b/web/chat/thread-list-provider.js
--- a/web/chat/thread-list-provider.js
+++ b/web/chat/thread-list-provider.js
@@ -17,7 +17,7 @@
   threadIsPending,
   useIsThreadInChatList,
 } from 'lib/shared/thread-utils.js';
-import { threadTypeIsSidebar } from 'lib/types/thread-types-enum.js';
+import { threadTypeIsSidebar } from 'lib/shared/threads/thread-specs.js';
 
 import { useSelector } from '../redux/redux-utils.js';
 import {
diff --git a/web/chat/thread-menu.react.js b/web/chat/thread-menu.react.js
--- a/web/chat/thread-menu.react.js
+++ b/web/chat/thread-menu.react.js
@@ -22,13 +22,15 @@
   useThreadHasPermission,
   viewerIsMember,
 } from 'lib/shared/thread-utils.js';
-import { type DMLeaveThreadOperation } from 'lib/types/dm-ops.js';
-import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
-import { threadPermissions } from 'lib/types/thread-permission-types.js';
 import {
   threadTypeIsPersonal,
   threadTypeIsPrivate,
   threadTypeIsSidebar,
+} from 'lib/shared/threads/thread-specs.js';
+import { type DMLeaveThreadOperation } from 'lib/types/dm-ops.js';
+import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
+import { threadPermissions } from 'lib/types/thread-permission-types.js';
+import {
   threadTypeIsThick,
   thickThreadTypes,
 } from 'lib/types/thread-types-enum.js';
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
@@ -53,6 +53,7 @@
   threadIsPending,
   threadIsPendingSidebar,
 } from 'lib/shared/thread-utils.js';
+import { threadTypeIsSidebar } from 'lib/shared/threads/thread-specs.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 import type {
   MediaMission,
@@ -72,10 +73,7 @@
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { Dispatch } from 'lib/types/redux-types.js';
 import { reportTypes } from 'lib/types/report-types.js';
-import {
-  threadTypeIsSidebar,
-  threadTypeIsThick,
-} from 'lib/types/thread-types-enum.js';
+import { threadTypeIsThick } from 'lib/types/thread-types-enum.js';
 import type { ThreadType } from 'lib/types/thread-types-enum.js';
 import {
   type ClientNewThinThreadRequest,
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
@@ -16,13 +16,11 @@
   threadUIName,
   useThreadHasPermission,
 } from 'lib/shared/thread-utils.js';
+import { threadTypeIsPersonal } from 'lib/shared/threads/thread-specs.js';
 import type { ThreadInfo } from 'lib/types/minimally-encoded-thread-permissions-types.js';
 import type { RelationshipButton } from 'lib/types/relationship-types.js';
 import { threadPermissions } from 'lib/types/thread-permission-types.js';
-import {
-  threadTypeIsPersonal,
-  threadTypes,
-} from 'lib/types/thread-types-enum.js';
+import { threadTypes } from 'lib/types/thread-types-enum.js';
 import { type ThreadChanges } from 'lib/types/thread-types.js';
 import { useResolvedThreadInfo } from 'lib/utils/entity-helpers.js';