diff --git a/lib/components/farcaster-data-handler.react.js b/lib/components/farcaster-data-handler.react.js
--- a/lib/components/farcaster-data-handler.react.js
+++ b/lib/components/farcaster-data-handler.react.js
@@ -2,23 +2,96 @@
 
 import * as React from 'react';
 
+import {
+  updateRelationships as serverUpdateRelationships,
+  updateRelationshipsActionTypes,
+} from '../actions/relationship-actions.js';
+import { FIDContext } from '../components/fid-provider.react.js';
+import { NeynarClientContext } from '../components/neynar-client-provider.react.js';
+import { cookieSelector } from '../selectors/keyserver-selectors.js';
+import { isLoggedIn } from '../selectors/user-selectors.js';
+import { IdentityClientContext } from '../shared/identity-client-context.js';
+import { relationshipActions } from '../types/relationship-types.js';
+import { useLegacyAshoatKeyserverCall } from '../utils/action-utils.js';
+import { authoritativeKeyserverID } from '../utils/authoritative-keyserver.js';
+import { useDispatchActionPromise } from '../utils/redux-promise-utils.js';
 import { useSelector } from '../utils/redux-utils.js';
+import { usingCommServicesAccessToken } from '../utils/services-utils.js';
 
 function FarcasterDataHandler(): React.Node {
   const isActive = useSelector(state => state.lifecycleState !== 'background');
 
-  const prevIsActiveRef = React.useRef<?boolean>();
+  const hasCurrentUserInfo = useSelector(isLoggedIn);
+  const cookie = useSelector(cookieSelector(authoritativeKeyserverID()));
+  const hasUserCookie = !!(cookie && cookie.startsWith('user='));
+  const loggedIn = hasCurrentUserInfo && hasUserCookie;
+
+  const neynarClient = React.useContext(NeynarClientContext)?.client;
+
+  const identityServiceClient = React.useContext(IdentityClientContext);
+  const getFarcasterUsers =
+    identityServiceClient?.identityClient.getFarcasterUsers;
+
+  const dispatchActionPromise = useDispatchActionPromise();
+  const updateRelationships = useLegacyAshoatKeyserverCall(
+    serverUpdateRelationships,
+  );
+  const createThreadsAndRobotextForFarcasterMutuals = React.useCallback(
+    (userIDs: $ReadOnlyArray<string>) =>
+      updateRelationships({
+        action: relationshipActions.FARCASTER_MUTUAL,
+        userIDs,
+      }),
+    [updateRelationships],
+  );
+
+  const userInfos = useSelector(state => state.userStore.userInfos);
+
+  const fid = React.useContext(FIDContext)?.fid;
+
+  const prevCanQueryRef = React.useRef<?boolean>();
   React.useEffect(() => {
-    if (isActive === prevIsActiveRef.current) {
+    if (!usingCommServicesAccessToken) {
       return;
     }
-    prevIsActiveRef.current = isActive;
-    if (!isActive) {
+
+    const canQuery = isActive && !!fid && loggedIn;
+    if (canQuery === prevCanQueryRef.current) {
       return;
     }
-    // app either just started, or just became active
-    // we will fetch Farcaster data here
-  }, [isActive]);
+    prevCanQueryRef.current = canQuery;
+
+    if (!loggedIn || !isActive || !fid || !neynarClient || !getFarcasterUsers) {
+      return;
+    }
+
+    void (async () => {
+      const followerFIDs = await neynarClient.fetchFriendFIDs(fid);
+
+      const commFCUsers = await getFarcasterUsers(followerFIDs);
+
+      const commUserIDs = commFCUsers.map(({ userID }) => userID);
+
+      const newCommUserIDs = commUserIDs.filter(userID => !userInfos[userID]);
+      if (newCommUserIDs.length === 0) {
+        return;
+      }
+
+      void dispatchActionPromise(
+        updateRelationshipsActionTypes,
+        createThreadsAndRobotextForFarcasterMutuals(newCommUserIDs),
+      );
+    })();
+  }, [
+    isActive,
+    fid,
+    loggedIn,
+    neynarClient,
+    getFarcasterUsers,
+    userInfos,
+    dispatchActionPromise,
+    createThreadsAndRobotextForFarcasterMutuals,
+  ]);
 
   return null;
 }