diff --git a/lib/permissions/prefixes.js b/lib/permissions/prefixes.js
index 3c0776420..8fac4d1c3 100644
--- a/lib/permissions/prefixes.js
+++ b/lib/permissions/prefixes.js
@@ -1,78 +1,90 @@
 // @flow
 
-import type {
-  ThreadPermission,
-  ThreadPermissionFilterPrefix,
-  ThreadPermissionPropagationPrefix,
-} from '../types/thread-permission-types.js';
 import {
+  type ThreadPermission,
+  type ThreadPermissionFilterPrefix,
+  type ThreadPermissionPropagationPrefix,
+  type ThreadPermissionMembershipPrefix,
   assertThreadPermissions,
   threadPermissionFilterPrefixes,
   threadPermissionPropagationPrefixes,
+  threadPermissionMembershipPrefixes,
 } from '../types/thread-permission-types.js';
 import {
   threadTypes,
   type ThreadType,
   threadTypeIsSidebar,
 } from '../types/thread-types-enum.js';
 
 type ParsedThreadPermissionString = {
   +permission: ThreadPermission,
   +propagationPrefix: ?ThreadPermissionPropagationPrefix,
   +filterPrefix: ?ThreadPermissionFilterPrefix,
+  +membershipPrefix: ?ThreadPermissionMembershipPrefix,
 };
 function parseThreadPermissionString(
   threadPermissionString: string,
 ): ParsedThreadPermissionString {
   let remainingString = threadPermissionString;
 
   let propagationPrefix;
   for (const key in threadPermissionPropagationPrefixes) {
     const prefix = threadPermissionPropagationPrefixes[key];
     if (!remainingString.startsWith(prefix)) {
       continue;
     }
     propagationPrefix = prefix;
     remainingString = remainingString.substr(prefix.length);
     break;
   }
 
   let filterPrefix;
   for (const key in threadPermissionFilterPrefixes) {
     const prefix = threadPermissionFilterPrefixes[key];
     if (!remainingString.startsWith(prefix)) {
       continue;
     }
     filterPrefix = prefix;
     remainingString = remainingString.substr(prefix.length);
     break;
   }
 
+  let membershipPrefix;
+  for (const key in threadPermissionMembershipPrefixes) {
+    const prefix = threadPermissionMembershipPrefixes[key];
+    if (!remainingString.startsWith(prefix)) {
+      continue;
+    }
+    membershipPrefix = prefix;
+    remainingString = remainingString.substr(prefix.length);
+    break;
+  }
+
   const permission = assertThreadPermissions(remainingString);
 
-  return { permission, propagationPrefix, filterPrefix };
+  return { permission, propagationPrefix, filterPrefix, membershipPrefix };
 }
 
 function includeThreadPermissionForThreadType(
   parsed: ParsedThreadPermissionString,
   threadType: ThreadType,
 ): boolean {
   if (
     threadType !== threadTypes.COMMUNITY_OPEN_SUBTHREAD &&
     threadType !== threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD &&
     !threadTypeIsSidebar(threadType) &&
     (parsed.filterPrefix === threadPermissionFilterPrefixes.OPEN ||
       parsed.filterPrefix === threadPermissionFilterPrefixes.OPEN_TOP_LEVEL)
   ) {
     return false;
   } else if (
     threadTypeIsSidebar(threadType) &&
     (parsed.filterPrefix === threadPermissionFilterPrefixes.TOP_LEVEL ||
       parsed.filterPrefix === threadPermissionFilterPrefixes.OPEN_TOP_LEVEL)
   ) {
     return false;
   }
   return true;
 }
 
 export { parseThreadPermissionString, includeThreadPermissionForThreadType };
diff --git a/lib/types/thread-permission-types.js b/lib/types/thread-permission-types.js
index 2d3b5e225..e68016864 100644
--- a/lib/types/thread-permission-types.js
+++ b/lib/types/thread-permission-types.js
@@ -1,361 +1,370 @@
 // @flow
 
 import invariant from 'invariant';
 import t, { type TDict, type TUnion, type TEnums } from 'tcomb';
 
 import { values } from '../utils/objects.js';
 import { tBool, tShape, tID } from '../utils/validation-utils.js';
 
 export const threadPermissionsDisabledByBlock = Object.freeze({
   VOICED: 'voiced',
   EDIT_ENTRIES: 'edit_entries',
   EDIT_THREAD_NAME: 'edit_thread',
   EDIT_THREAD_DESCRIPTION: 'edit_thread_description',
   EDIT_THREAD_COLOR: 'edit_thread_color',
   CREATE_SUBCHANNELS: 'create_subthreads',
   CREATE_SIDEBARS: 'create_sidebars',
   JOIN_THREAD: 'join_thread',
   EDIT_PERMISSIONS: 'edit_permissions',
   ADD_MEMBERS: 'add_members',
   REMOVE_MEMBERS: 'remove_members',
 });
 
 export const threadPermissionsNotAffectedByBlock = Object.freeze({
   KNOW_OF: 'know_of',
   VISIBLE: 'visible',
   DELETE_THREAD: 'delete_thread',
   CHANGE_ROLE: 'change_role',
   LEAVE_THREAD: 'leave_thread',
   REACT_TO_MESSAGE: 'react_to_message',
   EDIT_MESSAGE: 'edit_message',
   EDIT_THREAD_AVATAR: 'edit_thread_avatar',
   MANAGE_PINS: 'manage_pins',
   MANAGE_INVITE_LINKS: 'manage_invite_links',
   VOICED_IN_ANNOUNCEMENT_CHANNELS: 'voiced_in_announcement_channels',
   MANAGE_FARCASTER_CHANNEL_TAGS: 'manage_farcaster_channel_tags',
 });
 
 export type ThreadPermissionNotAffectedByBlock = $Values<
   typeof threadPermissionsNotAffectedByBlock,
 >;
 
 // When a new permission is added, if it should be configurable for a role, it
 // should be either added to an existing set or a new set alongside a
 // new user-facing permission. If it is a permission that should be ensured
 // across all roles, it should be added to `universalCommunityPermissions`.
 export const threadPermissions = Object.freeze({
   ...threadPermissionsDisabledByBlock,
   ...threadPermissionsNotAffectedByBlock,
 });
 export type ThreadPermission = $Values<typeof threadPermissions>;
 
 export function assertThreadPermissions(
   ourThreadPermissions: string,
 ): ThreadPermission {
   invariant(
     ourThreadPermissions === 'know_of' ||
       ourThreadPermissions === 'visible' ||
       ourThreadPermissions === 'voiced' ||
       ourThreadPermissions === 'edit_entries' ||
       ourThreadPermissions === 'edit_thread' ||
       ourThreadPermissions === 'edit_thread_description' ||
       ourThreadPermissions === 'edit_thread_color' ||
       ourThreadPermissions === 'delete_thread' ||
       ourThreadPermissions === 'create_subthreads' ||
       ourThreadPermissions === 'create_sidebars' ||
       ourThreadPermissions === 'join_thread' ||
       ourThreadPermissions === 'edit_permissions' ||
       ourThreadPermissions === 'add_members' ||
       ourThreadPermissions === 'remove_members' ||
       ourThreadPermissions === 'change_role' ||
       ourThreadPermissions === 'leave_thread' ||
       ourThreadPermissions === 'react_to_message' ||
       ourThreadPermissions === 'edit_message' ||
       ourThreadPermissions === 'edit_thread_avatar' ||
       ourThreadPermissions === 'manage_pins' ||
       ourThreadPermissions === 'manage_invite_links' ||
       ourThreadPermissions === 'voiced_in_announcement_channels' ||
       ourThreadPermissions === 'manage_farcaster_channel_tags',
     'string is not threadPermissions enum',
   );
   return ourThreadPermissions;
 }
 
 const threadPermissionValidator = t.enums.of(values(threadPermissions));
+
 export const threadPermissionPropagationPrefixes = Object.freeze({
   DESCENDANT: 'descendant_',
   CHILD: 'child_',
 });
 export type ThreadPermissionPropagationPrefix = $Values<
   typeof threadPermissionPropagationPrefixes,
 >;
+
 export const threadPermissionFilterPrefixes = Object.freeze({
   // includes only SIDEBAR, COMMUNITY_OPEN_SUBTHREAD,
   // COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD
   OPEN: 'open_',
   // excludes only SIDEBAR
   TOP_LEVEL: 'toplevel_',
   // includes only COMMUNITY_OPEN_SUBTHREAD,
   // COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD
   OPEN_TOP_LEVEL: 'opentoplevel_',
 });
 export type ThreadPermissionFilterPrefix = $Values<
   typeof threadPermissionFilterPrefixes,
 >;
 
+export const threadPermissionMembershipPrefixes = Object.freeze({
+  MEMBER: 'member_',
+});
+export type ThreadPermissionMembershipPrefix = $Values<
+  typeof threadPermissionMembershipPrefixes,
+>;
+
 // These are the set of user-facing permissions that we display as configurable
 // to the user when they are creating a custom role for their given community.
 // They are per-community rather than per-thread, so when configured they are
 // to be expected to be propagated across the community. Also notably,
 // `threadPermissions` is used on the keyserver for permission checks to
 // validate actions, but these `userSurfacedPermissions` are only used
 // on the client for the UI and propagated to the server. The
 // `configurableCommunityPermissions` mapping below is the association between
 // each userSurfacedPermission and a set of threadPermissions.
 export const userSurfacedPermissions = Object.freeze({
   EDIT_CALENDAR: 'edit_calendar',
   KNOW_OF_SECRET_CHANNELS: 'know_of_secret_channels',
   VOICED_IN_ANNOUNCEMENT_CHANNELS: 'voiced_in_announcement_channels',
   CREATE_AND_EDIT_CHANNELS: 'create_and_edit_channels',
   DELETE_CHANNELS: 'delete_channels',
   ADD_MEMBERS: 'add_members',
   REMOVE_MEMBERS: 'remove_members',
   CHANGE_ROLES: 'change_roles',
   EDIT_VISIBILITY: 'edit_visibility',
   MANAGE_PINS: 'manage_pins',
   REACT_TO_MESSAGES: 'react_to_messages',
   EDIT_MESSAGES: 'edit_messages',
   MANAGE_INVITE_LINKS: 'manage_invite_links',
   MANAGE_FARCASTER_CHANNEL_TAGS: 'manage_farcaster_channel_tags',
 });
 export type UserSurfacedPermission = $Values<typeof userSurfacedPermissions>;
 export const userSurfacedPermissionsSet: $ReadOnlySet<UserSurfacedPermission> =
   new Set(values(userSurfacedPermissions));
 export const userSurfacedPermissionValidator: TEnums = t.enums.of(
   values(userSurfacedPermissions),
 );
 
 const editCalendarPermission = {
   title: 'Edit calendar',
   description: 'Allows members to edit the community calendar',
   userSurfacedPermission: userSurfacedPermissions.EDIT_CALENDAR,
 };
 const editEntries = threadPermissions.EDIT_ENTRIES;
 const editCalendarPermissions = new Set([editEntries]);
 
 const knowOfSecretChannelsPermission = {
   title: 'Know of secret channels',
   description: 'Allows members to know of all secret channels',
   userSurfacedPermission: userSurfacedPermissions.KNOW_OF_SECRET_CHANNELS,
 };
 const descendantKnowOf =
   threadPermissionPropagationPrefixes.DESCENDANT + threadPermissions.KNOW_OF;
 const descendantVisible =
   threadPermissionPropagationPrefixes.DESCENDANT + threadPermissions.VISIBLE;
 const descendantTopLevelJoinThread =
   threadPermissionPropagationPrefixes.DESCENDANT +
   threadPermissionFilterPrefixes.TOP_LEVEL +
   threadPermissions.JOIN_THREAD;
 const descendantJoinThread =
   threadPermissionPropagationPrefixes.DESCENDANT +
   threadPermissions.JOIN_THREAD;
 const childJoinThread =
   threadPermissionPropagationPrefixes.CHILD + threadPermissions.JOIN_THREAD;
 const knowOfSecretChannelsPermissions = new Set([
   descendantKnowOf,
   descendantVisible,
   descendantTopLevelJoinThread,
   descendantJoinThread,
   childJoinThread,
 ]);
 
 const voicedPermission = {
   title: 'Voiced in announcement channels',
   description: 'Allows members to send messages in announcement channels',
   userSurfacedPermission:
     userSurfacedPermissions.VOICED_IN_ANNOUNCEMENT_CHANNELS,
 };
 const voicedInAnnouncementChannels =
   threadPermissions.VOICED_IN_ANNOUNCEMENT_CHANNELS;
 const descendantTopLevelVoicedInAnnouncementChannels =
   threadPermissionPropagationPrefixes.DESCENDANT +
   threadPermissionFilterPrefixes.TOP_LEVEL +
   threadPermissions.VOICED_IN_ANNOUNCEMENT_CHANNELS;
 const voicedPermissions = new Set([
   voicedInAnnouncementChannels,
   descendantTopLevelVoicedInAnnouncementChannels,
 ]);
 
 const createAndEditChannelsPermission = {
   title: 'Create and edit channels',
   description: 'Allows members to create new and edit existing channels',
   userSurfacedPermission: userSurfacedPermissions.CREATE_AND_EDIT_CHANNELS,
 };
 const editThreadName = threadPermissions.EDIT_THREAD_NAME;
 const editThreadDescription = threadPermissions.EDIT_THREAD_DESCRIPTION;
 const editThreadColor = threadPermissions.EDIT_THREAD_COLOR;
 const createSubchannels = threadPermissions.CREATE_SUBCHANNELS;
 const editThreadAvatar = threadPermissions.EDIT_THREAD_AVATAR;
 const createAndEditChannelsPermissions = new Set([
   editThreadName,
   editThreadDescription,
   editThreadColor,
   createSubchannels,
   editThreadAvatar,
 ]);
 
 const deleteChannelsPermission = {
   title: 'Delete channels',
   description: 'Allows members to delete channels',
   userSurfacedPermission: userSurfacedPermissions.DELETE_CHANNELS,
 };
 const deleteThread = threadPermissions.DELETE_THREAD;
 const deleteChannelsPermissions = new Set([deleteThread]);
 
 const addMembersPermission = {
   title: 'Add members',
   description: 'Allows members to add other members to channels',
   userSurfacedPermission: userSurfacedPermissions.ADD_MEMBERS,
 };
 const childOpenAddMembers =
   threadPermissionPropagationPrefixes.CHILD +
   threadPermissionFilterPrefixes.OPEN +
   threadPermissions.ADD_MEMBERS;
 const addMembersPermissions = new Set([childOpenAddMembers]);
 
 const removeMembersPermission = {
   title: 'Remove members',
   description: 'Allows members to remove anybody they can demote from channels',
   userSurfacedPermission: userSurfacedPermissions.REMOVE_MEMBERS,
 };
 const removeMembers = threadPermissions.REMOVE_MEMBERS;
 const removeMembersPermissions = new Set([removeMembers]);
 
 const changeRolePermission = {
   title: 'Change roles',
   description: 'Allows members to promote and demote other members',
   userSurfacedPermission: userSurfacedPermissions.CHANGE_ROLES,
 };
 const changeRole = threadPermissions.CHANGE_ROLE;
 const changeRolePermissions = new Set([changeRole]);
 
 const editVisibilityPermission = {
   title: 'Edit visibility',
   description: 'Allows members to edit visibility permissions of channels',
   userSurfacedPermission: userSurfacedPermissions.EDIT_VISIBILITY,
 };
 const editPermissions = threadPermissions.EDIT_PERMISSIONS;
 const editVisibilityPermissions = new Set([editPermissions]);
 
 const managePinsPermission = {
   title: 'Manage pins',
   description: 'Allows members to pin or unpin messages in channels',
   userSurfacedPermission: userSurfacedPermissions.MANAGE_PINS,
 };
 const managePins = threadPermissions.MANAGE_PINS;
 const managePinsPermissions = new Set([managePins]);
 
 const reactToMessagePermission = {
   title: 'React to messages',
   description: 'Allows members to add reactions to messages',
   userSurfacedPermission: userSurfacedPermissions.REACT_TO_MESSAGES,
 };
 const reactToMessage = threadPermissions.REACT_TO_MESSAGE;
 const reactToMessagePermissions = new Set([reactToMessage]);
 
 const editMessagePermission = {
   title: 'Edit messages',
   description: 'Allows members to edit their sent messages',
   userSurfacedPermission: userSurfacedPermissions.EDIT_MESSAGES,
 };
 const editMessage = threadPermissions.EDIT_MESSAGE;
 const editMessagePermissions = new Set([editMessage]);
 
 const manageInviteLinksPermission = {
   title: 'Manage invite links',
   description: 'Allows members to create and delete invite links',
   userSurfacedPermission: userSurfacedPermissions.MANAGE_INVITE_LINKS,
 };
 const manageInviteLinks = threadPermissions.MANAGE_INVITE_LINKS;
 const manageInviteLinksPermissions = new Set([manageInviteLinks]);
 
 const manageFarcasterChannelTagsPermission = {
   title: 'Manage Farcaster channel tags',
   description:
     'Allows members to associate your community with a Farcaster channel,' +
     ' or to delete the association',
   userSurfacedPermission: userSurfacedPermissions.MANAGE_FARCASTER_CHANNEL_TAGS,
 };
 const manageFarcasterChannelTags =
   threadPermissions.MANAGE_FARCASTER_CHANNEL_TAGS;
 const manageFarcasterChannelTagsPermissions = new Set([
   manageFarcasterChannelTags,
 ]);
 
 export type UserSurfacedPermissionOption = {
   +title: string,
   +description: string,
   +userSurfacedPermission: UserSurfacedPermission,
 };
 export const userSurfacedPermissionOptions: $ReadOnlySet<UserSurfacedPermissionOption> =
   new Set([
     editCalendarPermission,
     knowOfSecretChannelsPermission,
     voicedPermission,
     createAndEditChannelsPermission,
     deleteChannelsPermission,
     addMembersPermission,
     removeMembersPermission,
     changeRolePermission,
     editVisibilityPermission,
     managePinsPermission,
     reactToMessagePermission,
     editMessagePermission,
     manageInviteLinksPermission,
     manageFarcasterChannelTagsPermission,
   ]);
 
 type ConfigurableCommunityPermission = {
   +[permission: UserSurfacedPermission]: $ReadOnlySet<string>,
 };
 export const configurableCommunityPermissions: ConfigurableCommunityPermission =
   Object.freeze({
     [userSurfacedPermissions.EDIT_CALENDAR]: editCalendarPermissions,
     [userSurfacedPermissions.KNOW_OF_SECRET_CHANNELS]:
       knowOfSecretChannelsPermissions,
     [userSurfacedPermissions.VOICED_IN_ANNOUNCEMENT_CHANNELS]:
       voicedPermissions,
     [userSurfacedPermissions.CREATE_AND_EDIT_CHANNELS]:
       createAndEditChannelsPermissions,
     [userSurfacedPermissions.DELETE_CHANNELS]: deleteChannelsPermissions,
     [userSurfacedPermissions.ADD_MEMBERS]: addMembersPermissions,
     [userSurfacedPermissions.REMOVE_MEMBERS]: removeMembersPermissions,
     [userSurfacedPermissions.CHANGE_ROLES]: changeRolePermissions,
     [userSurfacedPermissions.EDIT_VISIBILITY]: editVisibilityPermissions,
     [userSurfacedPermissions.MANAGE_PINS]: managePinsPermissions,
     [userSurfacedPermissions.REACT_TO_MESSAGES]: reactToMessagePermissions,
     [userSurfacedPermissions.EDIT_MESSAGES]: editMessagePermissions,
     [userSurfacedPermissions.MANAGE_INVITE_LINKS]: manageInviteLinksPermissions,
     [userSurfacedPermissions.MANAGE_FARCASTER_CHANNEL_TAGS]:
       manageFarcasterChannelTagsPermissions,
   });
 
 export type ThreadPermissionInfo =
   | { +value: true, +source: string }
   | { +value: false, +source: null };
 export const threadPermissionInfoValidator: TUnion<ThreadPermissionInfo> =
   t.union([
     tShape({ value: tBool(true), source: tID }),
     tShape({ value: tBool(false), source: t.Nil }),
   ]);
 export type ThreadPermissionsBlob = {
   +[permission: string]: ThreadPermissionInfo,
 };
 export type ThreadRolePermissionsBlob = { +[permission: string]: boolean };
 export const threadRolePermissionsBlobValidator: TDict<ThreadRolePermissionsBlob> =
   t.dict(t.String, t.Boolean);
 export type ThreadPermissionsInfo = {
   +[permission: ThreadPermission]: ThreadPermissionInfo,
 };
 export const threadPermissionsInfoValidator: TDict<ThreadPermissionsInfo> =
   t.dict(threadPermissionValidator, threadPermissionInfoValidator);