diff --git a/keyserver/src/updaters/relationship-updaters.js b/keyserver/src/updaters/relationship-updaters.js
index fd8ac111c..292dbd42c 100644
--- a/keyserver/src/updaters/relationship-updaters.js
+++ b/keyserver/src/updaters/relationship-updaters.js
@@ -1,371 +1,386 @@
 // @flow
 
 import invariant from 'invariant';
 
 import { sortUserIDs } from 'lib/shared/relationship-utils.js';
 import { messageTypes } from 'lib/types/message-types-enum.js';
 import {
   type RelationshipRequest,
   type RelationshipErrors,
   type UndirectedRelationshipRow,
   relationshipActions,
   undirectedStatus,
   directedStatus,
 } from 'lib/types/relationship-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
 import type { NewThreadResponse } from 'lib/types/thread-types.js';
 import { updateTypes } from 'lib/types/update-types-enum.js';
 import { type UpdateData } from 'lib/types/update-types.js';
 import { cartesianProduct } from 'lib/utils/array.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { promiseAll } from 'lib/utils/promises.js';
 
 import createMessages from '../creators/message-creator.js';
 import { createThread } from '../creators/thread-creator.js';
 import { createUpdates } from '../creators/update-creator.js';
 import { dbQuery, SQL, mergeOrConditions } from '../database/database.js';
 import { fetchFriendRequestRelationshipOperations } from '../fetchers/relationship-fetchers.js';
 import { fetchUserInfos } from '../fetchers/user-fetchers.js';
 import type { Viewer } from '../session/viewer.js';
 
 async function updateRelationships(
   viewer: Viewer,
   request: RelationshipRequest,
 ): Promise<RelationshipErrors> {
   const { action } = request;
 
   if (!viewer.loggedIn) {
     throw new ServerError('not_logged_in');
   }
 
   const uniqueUserIDs = [...new Set(request.userIDs)];
   const users = await fetchUserInfos(uniqueUserIDs);
 
   let errors: RelationshipErrors = {};
   const userIDs: string[] = [];
   for (const userID of uniqueUserIDs) {
     if (userID === viewer.userID || !users[userID].username) {
       const acc = errors.invalid_user || [];
       errors.invalid_user = [...acc, userID];
     } else {
       userIDs.push(userID);
     }
   }
   if (!userIDs.length) {
     return Object.freeze({ ...errors });
   }
 
   const updateIDs = [];
   if (action === relationshipActions.FRIEND) {
     // We have to create personal threads before setting the relationship
     // status. By doing that we make sure that failed thread creation is
     // reported to the caller and can be repeated - there should be only
     // one PERSONAL thread per a pair of users and we can safely call it
     // repeatedly.
     const threadIDPerUser = await createPersonalThreads(viewer, request);
     const { userRelationshipOperations, errors: friendRequestErrors } =
       await fetchFriendRequestRelationshipOperations(viewer, userIDs);
     errors = { ...errors, ...friendRequestErrors };
 
     const undirectedInsertRows = [];
     const directedInsertRows = [];
     const directedDeleteIDs = [];
     const messageDatas = [];
     const now = Date.now();
     for (const userID in userRelationshipOperations) {
       const operations = userRelationshipOperations[userID];
       const ids = sortUserIDs(viewer.userID, userID);
 
       if (operations.length) {
         updateIDs.push(userID);
       }
 
       for (const operation of operations) {
         if (operation === 'delete_directed') {
           directedDeleteIDs.push(userID);
         } else if (operation === 'friend') {
           const [user1, user2] = ids;
           const status = undirectedStatus.FRIEND;
           undirectedInsertRows.push({ user1, user2, status });
           messageDatas.push({
             type: messageTypes.LEGACY_UPDATE_RELATIONSHIP,
             threadID: threadIDPerUser[userID],
             creatorID: viewer.userID,
             targetID: userID,
             time: now,
             operation: 'request_accepted',
           });
         } else if (operation === 'pending_friend') {
           const status = directedStatus.PENDING_FRIEND;
           directedInsertRows.push([viewer.userID, userID, status]);
           messageDatas.push({
             type: messageTypes.LEGACY_UPDATE_RELATIONSHIP,
             threadID: threadIDPerUser[userID],
             creatorID: viewer.userID,
             targetID: userID,
             time: now,
             operation: 'request_sent',
           });
         } else if (operation === 'know_of') {
           const [user1, user2] = ids;
           const status = undirectedStatus.KNOW_OF;
           undirectedInsertRows.push({ user1, user2, status });
         } else {
           invariant(false, `unexpected relationship operation ${operation}`);
         }
       }
     }
 
     const promises: Array<Promise<mixed>> = [
       updateUndirectedRelationships(undirectedInsertRows),
     ];
     if (directedInsertRows.length) {
       const directedInsertQuery = SQL`
         INSERT INTO relationships_directed (user1, user2, status)
         VALUES ${directedInsertRows}
         ON DUPLICATE KEY UPDATE status = VALUE(status)
       `;
       promises.push(dbQuery(directedInsertQuery));
     }
     if (directedDeleteIDs.length) {
       const directedDeleteQuery = SQL`
         DELETE FROM relationships_directed
         WHERE 
           (user1 = ${viewer.userID} AND user2 IN (${directedDeleteIDs})) OR
           (status = ${directedStatus.PENDING_FRIEND} AND 
             user1 IN (${directedDeleteIDs}) AND user2 = ${viewer.userID})
       `;
       promises.push(dbQuery(directedDeleteQuery));
     }
     if (messageDatas.length > 0) {
       promises.push(createMessages(viewer, messageDatas, 'broadcast'));
     }
 
     await Promise.all(promises);
   } else if (action === relationshipActions.UNFRIEND) {
     updateIDs.push(...userIDs);
 
     const updateRows = userIDs.map(userID => {
       const [user1, user2] = sortUserIDs(viewer.userID, userID);
       return { user1, user2, status: undirectedStatus.KNOW_OF };
     });
 
     const deleteQuery = SQL`
       DELETE FROM relationships_directed
       WHERE 
         status = ${directedStatus.PENDING_FRIEND} AND 
         (user1 = ${viewer.userID} AND user2 IN (${userIDs}) OR 
           user1 IN (${userIDs}) AND user2 = ${viewer.userID})
     `;
 
     await Promise.all([
       updateUndirectedRelationships(updateRows, false),
       dbQuery(deleteQuery),
     ]);
   } else if (action === relationshipActions.BLOCK) {
     updateIDs.push(...userIDs);
 
     const directedRows = [];
     const undirectedRows = [];
     for (const userID of userIDs) {
       directedRows.push([viewer.userID, userID, directedStatus.BLOCKED]);
       const [user1, user2] = sortUserIDs(viewer.userID, userID);
       undirectedRows.push({ user1, user2, status: undirectedStatus.KNOW_OF });
     }
 
     const directedInsertQuery = SQL`
       INSERT INTO relationships_directed (user1, user2, status)
       VALUES ${directedRows}
       ON DUPLICATE KEY UPDATE status = VALUE(status)
     `;
     const directedDeleteQuery = SQL`
       DELETE FROM relationships_directed
       WHERE status = ${directedStatus.PENDING_FRIEND} AND 
         user1 IN (${userIDs}) AND user2 = ${viewer.userID}
     `;
 
     await Promise.all([
       dbQuery(directedInsertQuery),
       dbQuery(directedDeleteQuery),
       updateUndirectedRelationships(undirectedRows, false),
     ]);
   } else if (action === relationshipActions.UNBLOCK) {
     updateIDs.push(...userIDs);
 
     const query = SQL`
       DELETE FROM relationships_directed
       WHERE status = ${directedStatus.BLOCKED} AND 
         user1 = ${viewer.userID} AND user2 IN (${userIDs})
     `;
     await dbQuery(query);
+  } else if (action === relationshipActions.FARCASTER_MUTUAL) {
+    // We have to create personal threads before setting the relationship
+    // status. By doing that we make sure that failed thread creation is
+    // reported to the caller and can be repeated - there should be only
+    // one PERSONAL thread per a pair of users and we can safely call it
+    // repeatedly.
+    await createPersonalThreads(viewer, request);
+    const insertRows = request.userIDs.map(otherUserID => {
+      const [user1, user2] = sortUserIDs(viewer.userID, otherUserID);
+      return { user1, user2, status: undirectedStatus.KNOW_OF };
+    });
+    const updateDatas = await updateChangedUndirectedRelationships(insertRows);
+    await createUpdates(updateDatas);
   } else {
     invariant(false, `action ${action} is invalid or not supported currently`);
   }
 
   await createUpdates(
     updateDatasForUserPairs(cartesianProduct([viewer.userID], updateIDs)),
   );
 
   return Object.freeze({ ...errors });
 }
 
 function updateDatasForUserPairs(
   userPairs: $ReadOnlyArray<[string, string]>,
 ): UpdateData[] {
   const time = Date.now();
   const updateDatas: Array<UpdateData> = [];
   for (const [user1, user2] of userPairs) {
     updateDatas.push({
       type: updateTypes.UPDATE_USER,
       userID: user1,
       time,
       updatedUserID: user2,
     });
     updateDatas.push({
       type: updateTypes.UPDATE_USER,
       userID: user2,
       time,
       updatedUserID: user1,
     });
   }
   return updateDatas;
 }
 
 async function updateUndirectedRelationships(
   changeset: UndirectedRelationshipRow[],
   greatest: boolean = true,
 ) {
   if (!changeset.length) {
     return;
   }
 
   const rows = changeset.map(row => [row.user1, row.user2, row.status]);
   const query = SQL`
     INSERT INTO relationships_undirected (user1, user2, status)
     VALUES ${rows}
   `;
   if (greatest) {
     query.append(
       SQL`ON DUPLICATE KEY UPDATE status = GREATEST(status, VALUE(status))`,
     );
   } else {
     query.append(SQL`ON DUPLICATE KEY UPDATE status = VALUE(status)`);
   }
   await dbQuery(query);
 }
 
 async function updateChangedUndirectedRelationships(
   changeset: UndirectedRelationshipRow[],
 ): Promise<UpdateData[]> {
   if (changeset.length === 0) {
     return [];
   }
 
   const user2ByUser1: Map<string, Set<string>> = new Map();
   for (const { user1, user2 } of changeset) {
     if (!user2ByUser1.has(user1)) {
       user2ByUser1.set(user1, new Set());
     }
     user2ByUser1.get(user1)?.add(user2);
   }
 
   const selectQuery = SQL`
     SELECT user1, user2, status
     FROM relationships_undirected
     WHERE
   `;
   const conditions = [];
   for (const [user1, users] of user2ByUser1) {
     conditions.push(SQL`(user1 = ${user1} AND user2 IN (${[...users]}))`);
   }
   selectQuery.append(mergeOrConditions(conditions));
 
   const [result] = await dbQuery(selectQuery);
   const existingStatuses = new Map<string, number>();
   for (const row of result) {
     existingStatuses.set(`${row.user1}|${row.user2}`, row.status);
   }
 
   const insertRows = [];
   for (const row of changeset) {
     const existingStatus = existingStatuses.get(`${row.user1}|${row.user2}`);
     if (!existingStatus || existingStatus < row.status) {
       insertRows.push([row.user1, row.user2, row.status]);
     }
   }
   if (insertRows.length === 0) {
     return [];
   }
   const insertQuery = SQL`
     INSERT INTO relationships_undirected (user1, user2, status)
     VALUES ${insertRows}
     ON DUPLICATE KEY UPDATE status = GREATEST(status, VALUE(status))
   `;
   await dbQuery(insertQuery);
 
   return updateDatasForUserPairs(
     insertRows.map(([user1, user2]) => [user1, user2]),
   );
 }
 
 async function createPersonalThreads(
   viewer: Viewer,
   request: RelationshipRequest,
 ) {
   invariant(
-    request.action === relationshipActions.FRIEND,
-    'We should only create a PERSONAL threads when sending a FRIEND request, ' +
-      `but we tried to do that for ${request.action}`,
+    request.action === relationshipActions.FRIEND ||
+      request.action === relationshipActions.FARCASTER_MUTUAL,
+    'We should only create a PERSONAL threads when sending FRIEND or ' +
+      'FARCASTER_MUTUAL requests, but we tried to do that for ' +
+      request.action,
   );
 
   const threadIDPerUser: { [string]: string } = {};
 
   const personalThreadsQuery = SQL`
     SELECT t.id AS threadID, m2.user AS user2
     FROM threads t
     INNER JOIN memberships m1
       ON m1.thread = t.id AND m1.user = ${viewer.userID}
     INNER JOIN memberships m2
       ON m2.thread = t.id AND m2.user IN (${request.userIDs})
     WHERE t.type = ${threadTypes.PERSONAL}
       AND m1.role > 0
       AND m2.role > 0
   `;
   const [personalThreadsResult] = await dbQuery(personalThreadsQuery);
 
   for (const row of personalThreadsResult) {
     const user2 = row.user2.toString();
     threadIDPerUser[user2] = row.threadID.toString();
   }
 
   const threadCreationPromises: { [string]: Promise<NewThreadResponse> } = {};
   for (const userID of request.userIDs) {
     if (threadIDPerUser[userID]) {
       continue;
     }
     threadCreationPromises[userID] = createThread(
       viewer,
       {
         type: threadTypes.PERSONAL,
         initialMemberIDs: [userID],
       },
       { forceAddMembers: true, updatesForCurrentSession: 'broadcast' },
     );
   }
 
   const personalThreadPerUser = await promiseAll(threadCreationPromises);
 
   for (const userID in personalThreadPerUser) {
     const newThread = personalThreadPerUser[userID];
     threadIDPerUser[userID] = newThread.newThreadID;
   }
 
   return threadIDPerUser;
 }
 
 export {
   updateRelationships,
   updateDatasForUserPairs,
   updateUndirectedRelationships,
   updateChangedUndirectedRelationships,
 };
diff --git a/lib/types/relationship-types.js b/lib/types/relationship-types.js
index 5d757c45a..9a1e28efe 100644
--- a/lib/types/relationship-types.js
+++ b/lib/types/relationship-types.js
@@ -1,82 +1,83 @@
 // @flow
 
 import type { TRefinement } from 'tcomb';
 
 import type { AccountUserInfo } from './user-types.js';
 import { values } from '../utils/objects.js';
 import { tNumEnum } from '../utils/validation-utils.js';
 
 export const undirectedStatus = Object.freeze({
   KNOW_OF: 0,
   FRIEND: 2,
 });
 export type UndirectedStatus = $Values<typeof undirectedStatus>;
 
 export const directedStatus = Object.freeze({
   PENDING_FRIEND: 1,
   BLOCKED: 3,
 });
 export type DirectedStatus = $Values<typeof directedStatus>;
 
 export const userRelationshipStatus = Object.freeze({
   REQUEST_SENT: 1,
   REQUEST_RECEIVED: 2,
   FRIEND: 3,
   BLOCKED_BY_VIEWER: 4,
   BLOCKED_VIEWER: 5,
   BOTH_BLOCKED: 6,
 });
 export type UserRelationshipStatus = $Values<typeof userRelationshipStatus>;
 export const userRelationshipStatusValidator: TRefinement<number> = tNumEnum(
   values(userRelationshipStatus),
 );
 
 export const relationshipActions = Object.freeze({
   FRIEND: 'friend',
   UNFRIEND: 'unfriend',
   BLOCK: 'block',
   UNBLOCK: 'unblock',
+  FARCASTER_MUTUAL: 'farcaster',
 });
 export type RelationshipAction = $Values<typeof relationshipActions>;
 export const relationshipActionsList: $ReadOnlyArray<RelationshipAction> =
   values(relationshipActions);
 
 export const relationshipButtons = Object.freeze({
   FRIEND: 'friend',
   UNFRIEND: 'unfriend',
   BLOCK: 'block',
   UNBLOCK: 'unblock',
   ACCEPT: 'accept',
   WITHDRAW: 'withdraw',
   REJECT: 'reject',
 });
 export type RelationshipButton = $Values<typeof relationshipButtons>;
 
 export type RelationshipRequest = {
   action: RelationshipAction,
   userIDs: $ReadOnlyArray<string>,
 };
 
 type SharedRelationshipRow = {
   user1: string,
   user2: string,
 };
 export type DirectedRelationshipRow = {
   ...SharedRelationshipRow,
   status: DirectedStatus,
 };
 export type UndirectedRelationshipRow = {
   ...SharedRelationshipRow,
   status: UndirectedStatus,
 };
 
 export type RelationshipErrors = Partial<{
   invalid_user: string[],
   already_friends: string[],
   user_blocked: string[],
 }>;
 
 export type UserRelationships = {
   +friends: $ReadOnlyArray<AccountUserInfo>,
   +blocked: $ReadOnlyArray<AccountUserInfo>,
 };