feat: federate friends/social system across connected instances

Rewrites socialStore to aggregate friends and requests from all connected
instances using Promise.allSettled. Parses user@domain in friend requests
to route to the correct instance. Removes !isHome guards on social WS
events so remote friend requests arrive in real-time. Shows "via hostname"
labels on remote friends/requests in the UI.

packages/web/src/components/chat/FriendsPage.test.tsx

@@ -3,7 +3,7 @@ import { render, screen, waitFor } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { MemoryRouter } from 'react-router-dom';
 import { FriendsPage } from './FriendsPage';
-import { useSocialStore } from '../../stores/socialStore';
+import { useSocialStore, type TaggedFriend, type TaggedFriendRequest } from '../../stores/socialStore';
 import { useServerStore } from '../../stores/serverStore';
 import type { Friend, FriendRequest } from '@backspace/shared';
 
@@ -25,6 +25,15 @@ vi.mock('../../api/client', () => ({
   },
 }));
 
+// Mock the instanceStore (imported by socialStore)
+vi.mock('../../stores/instanceStore', () => ({
+  useInstanceStore: {
+    getState: () => ({ instances: [] }),
+    setState: vi.fn(),
+    subscribe: vi.fn(),
+  },
+}));
+
 const mockNavigate = vi.fn();
 vi.mock('react-router-dom', async () => {
   const actual = await vi.importActual('react-router-dom');
@@ -34,7 +43,7 @@ vi.mock('react-router-dom', async () => {
   };
 });
 
-const makeFriend = (overrides: Partial<Friend> = {}): Friend => ({
+const makeFriend = (overrides: Partial<TaggedFriend> = {}): TaggedFriend => ({
   id: 'friend-1',
   username: 'testfriend',
   displayName: 'Test Friend',
@@ -43,15 +52,19 @@ const makeFriend = (overrides: Partial<Friend> = {}): Friend => ({
   customStatus: null,
   createdAt: Date.now(),
   addedAt: Date.now(),
+  homeUserId: null,
+  homeInstance: null,
+  _instanceOrigin: '',
   ...overrides,
 });
 
-const makeRequest = (overrides: Partial<FriendRequest> = {}): FriendRequest => ({
+const makeRequest = (overrides: Partial<TaggedFriendRequest> = {}): TaggedFriendRequest => ({
   id: 'req-1',
   fromId: 'other-user',
   toId: 'current-user',
   status: 'pending',
   createdAt: Date.now(),
+  _instanceOrigin: '',
   user: {
     id: 'other-user',
     username: 'otheruser',

packages/web/src/components/chat/FriendsPage.tsx

@@ -1,12 +1,12 @@
 import React, { useEffect, useState } from 'react';
 import { useNavigate } from 'react-router-dom';
-import { useSocialStore } from '../../stores/socialStore';
+import { useSocialStore, type TaggedFriend, type TaggedFriendRequest } from '../../stores/socialStore';
 import { useServerStore } from '../../stores/serverStore';
+import { useInstanceStore } from '../../stores/instanceStore';
 import { Avatar } from '../ui/Avatar';
 import { MemberListToggleButton } from '../layout/MemberListToggleButton';
 import { LoadingSpinner } from '../ui/LoadingSpinner';
 import { api } from '../../api/client';
-import type { Friend, FriendRequest } from '@backspace/shared';
 
 type Tab = 'online' | 'all' | 'pending' | 'add';
 
@@ -51,9 +51,14 @@ export function FriendsPage() {
     }
   };
 
-  const handleOpenDm = async (friendId: string) => {
+  const handleOpenDm = async (friendId: string, instanceOrigin: string) => {
     try {
-      const dmChannel = await api.dm.create({ userId: friendId });
+      let client = api;
+      if (instanceOrigin) {
+        const instance = useInstanceStore.getState().instances.find(i => i.origin === instanceOrigin);
+        if (instance?.api) client = instance.api;
+      }
+      const dmChannel = await client.dm.create({ userId: friendId });
       addDmChannel(dmChannel);
       navigate(`/channels/@me/${dmChannel.id}`);
     } catch (err) {
@@ -84,7 +89,7 @@ export function FriendsPage() {
               </div>
             ) : (
               onlineFriends.map(friend => (
-                <FriendItem key={friend.id} friend={friend} onRemove={() => removeFriend(friend.id)} onDm={() => handleOpenDm(friend.id)} />
+                <FriendItem key={`${friend.id}:${friend._instanceOrigin}`} friend={friend} onRemove={() => removeFriend(friend.id)} onDm={() => handleOpenDm(friend.id, friend._instanceOrigin)} />
               ))
             )}
           </div>
@@ -101,7 +106,7 @@ export function FriendsPage() {
               </div>
             ) : (
               friends.map(friend => (
-                <FriendItem key={friend.id} friend={friend} onRemove={() => removeFriend(friend.id)} onDm={() => handleOpenDm(friend.id)} />
+                <FriendItem key={`${friend.id}:${friend._instanceOrigin}`} friend={friend} onRemove={() => removeFriend(friend.id)} onDm={() => handleOpenDm(friend.id, friend._instanceOrigin)} />
               ))
             )}
           </div>
@@ -120,7 +125,7 @@ export function FriendsPage() {
               <>
                 {pendingIncoming.map(req => (
                   <RequestItem
-                    key={req.id}
+                    key={`${req.id}:${req._instanceOrigin}`}
                     request={req}
                     type="incoming"
                     onAccept={() => updateFriendRequest(req.id, 'accepted')}
@@ -129,7 +134,7 @@ export function FriendsPage() {
                 ))}
                 {pendingOutgoing.map(req => (
                   <RequestItem
-                    key={req.id}
+                    key={`${req.id}:${req._instanceOrigin}`}
                     request={req}
                     type="outgoing"
                     onCancel={() => cancelFriendRequest(req.id)}
@@ -227,7 +232,8 @@ function TabButton({ children, active, onClick }: { children: React.ReactNode, a
   );
 }
 
-function FriendItem({ friend, onRemove, onDm }: { friend: Friend, onRemove: () => void, onDm: () => void }) {
+function FriendItem({ friend, onRemove, onDm }: { friend: TaggedFriend, onRemove: () => void, onDm: () => void }) {
+  const instanceLabel = friend._instanceOrigin ? (() => { try { return new URL(friend._instanceOrigin).host; } catch { return friend._instanceOrigin; } })() : '';
   return (
     <div className="flex items-center justify-between px-3 h-[62px] rounded-[8px] hover:bg-interactive-hover group transition-colors border-t border-interactive-muted mx-2">
       <div className="flex items-center gap-3">
@@ -237,7 +243,12 @@ function FriendItem({ friend, onRemove, onDm }: { friend: Friend, onRemove: () =
             <span className="text-txt-primary font-semibold text-[15px]">{friend.displayName ?? friend.username}</span>
             <span className="text-txt-tertiary text-[13px] opacity-0 group-hover:opacity-100 transition-opacity font-medium">@{friend.username}</span>
           </div>
+          <div className="flex items-center gap-1.5">
             <span className="text-[12px] text-txt-tertiary font-medium uppercase">{friend.status}</span>
+            {instanceLabel && (
+              <span className="text-[11px] text-txt-tertiary/60 font-medium">via {instanceLabel}</span>
+            )}
+          </div>
         </div>
       </div>
       <div className="flex items-center gap-2 opacity-0 group-hover:opacity-100 transition-opacity pr-2">
@@ -265,7 +276,7 @@ function FriendItem({ friend, onRemove, onDm }: { friend: Friend, onRemove: () =
 }
 
 function RequestItem({ request, type, onAccept, onDecline, onCancel }: {
-  request: FriendRequest;
+  request: TaggedFriendRequest;
   type: 'incoming' | 'outgoing';
   onAccept?: () => void;
   onDecline?: () => void;
@@ -273,6 +284,7 @@ function RequestItem({ request, type, onAccept, onDecline, onCancel }: {
 }) {
   const user = request.user;
   if (!user) return null;
+  const instanceLabel = request._instanceOrigin ? (() => { try { return new URL(request._instanceOrigin).host; } catch { return request._instanceOrigin; } })() : '';
 
   return (
     <div className="flex items-center justify-between px-3 py-2.5 rounded-lg hover:bg-interactive-hover group transition-colors border-t border-interactive-muted mx-2">
@@ -283,7 +295,12 @@ function RequestItem({ request, type, onAccept, onDecline, onCancel }: {
             <span className="text-txt-primary font-bold text-sm">{user.displayName ?? user.username}</span>
             <span className="text-txt-tertiary text-xs">@{user.username}</span>
           </div>
+          <div className="flex items-center gap-1.5">
             <span className="text-xs text-txt-tertiary">{type === 'incoming' ? 'Incoming Friend Request' : 'Outgoing Friend Request'}</span>
+            {instanceLabel && (
+              <span className="text-[11px] text-txt-tertiary/60 font-medium">via {instanceLabel}</span>
+            )}
+          </div>
         </div>
       </div>
       <div className="flex items-center gap-2">

packages/web/src/hooks/useWebSocket.ts

@@ -316,26 +316,23 @@ function handleEvent(origin: string, event: ServerEvent): void {
       onReactionRemoved(event.messageId, event.userId, event.emoji);
       break;
 
-    // ─── Social events (home-only) ──────────────────────────────────────────
+    // ─── Social events (all origins — federation) ──────────────────────────
 
     case 'friend_request_received': {
-      if (!isHome) break;
       const { addIncomingRequest } = useSocialStore.getState();
-      addIncomingRequest(event.request);
+      addIncomingRequest(event.request, origin);
       break;
     }
 
     case 'friend_request_accepted': {
-      if (!isHome) break;
       const { addFriendFromAccepted } = useSocialStore.getState();
-      addFriendFromAccepted(event.friend, event.requestId);
+      addFriendFromAccepted(event.friend, event.requestId, origin);
       break;
     }
 
     case 'friend_removed': {
-      if (!isHome) break;
       const { removeFriendLocally } = useSocialStore.getState();
-      removeFriendLocally(event.userId);
+      removeFriendLocally(event.userId, origin);
       break;
     }
 
@@ -481,6 +478,29 @@ function handleEvent(origin: string, event: ServerEvent): void {
       break;
     }
 
+    // ─── Join request events (home-only) ────────────────────────────────
+
+    case 'join_request_received': {
+      if (!isHome) break;
+      console.log('[WebSocket] Join request received from', event.request.user?.username ?? event.request.userId);
+      break;
+    }
+
+    case 'join_request_accepted': {
+      if (!isHome) break;
+      // Add the server to our server list
+      const { addServerFromReady } = useServerStore.getState();
+      addServerFromReady(origin, event.server);
+      console.log('[WebSocket] Join request accepted for server', event.server.name);
+      break;
+    }
+
+    case 'join_request_declined': {
+      if (!isHome) break;
+      console.log('[WebSocket] Join request declined for server', event.request.serverId);
+      break;
+    }
+
     case 'pong':
       break;
 

packages/web/src/stores/socialStore.ts

@@ -1,10 +1,26 @@
 import { create } from 'zustand';
 import type { Friend, FriendRequest, User } from '@backspace/shared';
 import { api } from '../api/client';
+import { useInstanceStore } from './instanceStore';
+
+// ─── Tagged types (origin tracking for federation) ───────────────────────────
+
+export type TaggedFriend = Friend & { _instanceOrigin: string };
+export type TaggedFriendRequest = FriendRequest & { _instanceOrigin: string };
+
+// ─── Helpers ─────────────────────────────────────────────────────────────────
+
+function getApiForOrigin(origin: string) {
+  if (!origin) return api;
+  const instance = useInstanceStore.getState().instances.find(i => i.origin === origin);
+  return instance?.api ?? api;
+}
+
+// ─── Store ───────────────────────────────────────────────────────────────────
 
 interface SocialState {
-  friends: Friend[];
+  friends: TaggedFriend[];
-  requests: FriendRequest[];
+  requests: TaggedFriendRequest[];
   isLoading: boolean;
   error: string | null;
   loadFriends: () => Promise<void>;
@@ -14,10 +30,10 @@ interface SocialState {
   cancelFriendRequest: (id: string) => Promise<void>;
   removeFriend: (id: string) => Promise<void>;
   searchUsers: (query: string) => Promise<User[]>;
-  addIncomingRequest: (request: FriendRequest) => void;
+  addIncomingRequest: (request: FriendRequest, origin: string) => void;
-  addFriendFromAccepted: (friend: Friend, requestId: string) => void;
+  addFriendFromAccepted: (friend: Friend, requestId: string, origin: string) => void;
   updateFriendPresence: (userId: string, status: string) => void;
-  removeFriendLocally: (userId: string) => void;
+  removeFriendLocally: (userId: string, origin: string) => void;
   reset: () => void;
 }
 
@@ -30,8 +46,31 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   loadFriends: async () => {
     set({ isLoading: true, error: null });
     try {
-      const friends = await api.social.friends();
+      const instances = useInstanceStore.getState().instances;
-      set({ friends, isLoading: false });
+      const connectedInstances = instances.filter(i => i.status === 'connected');
+
+      const results = await Promise.allSettled([
+        api.social.friends().then(friends => ({ friends, origin: '' })),
+        ...connectedInstances.map(inst =>
+          inst.api.social.friends().then(friends => ({ friends, origin: inst.origin }))
+        ),
+      ]);
+
+      const allFriends: TaggedFriend[] = [];
+      const seen = new Set<string>();
+
+      for (const result of results) {
+        if (result.status !== 'fulfilled') continue;
+        const { friends, origin } = result.value;
+        for (const friend of friends) {
+          const key = `${friend.id}:${origin}`;
+          if (seen.has(key)) continue;
+          seen.add(key);
+          allFriends.push({ ...friend, _instanceOrigin: origin });
+        }
+      }
+
+      set({ friends: allFriends, isLoading: false });
     } catch (err) {
       set({ error: (err as Error).message, isLoading: false });
     }
@@ -40,8 +79,31 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   loadRequests: async () => {
     set({ isLoading: true, error: null });
     try {
-      const requests = await api.social.requests();
+      const instances = useInstanceStore.getState().instances;
-      set({ requests, isLoading: false });
+      const connectedInstances = instances.filter(i => i.status === 'connected');
+
+      const results = await Promise.allSettled([
+        api.social.requests().then(requests => ({ requests, origin: '' })),
+        ...connectedInstances.map(inst =>
+          inst.api.social.requests().then(requests => ({ requests, origin: inst.origin }))
+        ),
+      ]);
+
+      const allRequests: TaggedFriendRequest[] = [];
+      const seen = new Set<string>();
+
+      for (const result of results) {
+        if (result.status !== 'fulfilled') continue;
+        const { requests, origin } = result.value;
+        for (const request of requests) {
+          const key = `${request.id}:${origin}`;
+          if (seen.has(key)) continue;
+          seen.add(key);
+          allRequests.push({ ...request, _instanceOrigin: origin });
+        }
+      }
+
+      set({ requests: allRequests, isLoading: false });
     } catch (err) {
       set({ error: (err as Error).message, isLoading: false });
     }
@@ -50,7 +112,43 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   sendFriendRequest: async (username: string) => {
     set({ isLoading: true, error: null });
     try {
+      const atIndex = username.lastIndexOf('@');
+
+      if (atIndex === -1) {
+        // No @ → local user on home instance
         await api.social.sendRequest(username);
+      } else {
+        const baseName = username.slice(0, atIndex);
+        const domain = username.slice(atIndex + 1);
+
+        // Check if domain matches home instance
+        if (domain === window.location.host) {
+          // Strip domain, send to home API
+          await api.social.sendRequest(baseName);
+        } else {
+          // Find a connected instance matching this domain
+          const instances = useInstanceStore.getState().instances;
+          const match = instances.find(inst => {
+            try {
+              return new URL(inst.origin).host === domain;
+            } catch {
+              return false;
+            }
+          });
+
+          if (!match) {
+            throw new Error(`Not connected to ${domain}. Add it as an instance in Settings first.`);
+          }
+
+          if (match.status !== 'connected') {
+            throw new Error(`Instance ${domain} is not currently connected. Check your connection in Settings.`);
+          }
+
+          // On the remote instance, the user is just "alice", not "alice@orbit"
+          await match.api.social.sendRequest(baseName);
+        }
+      }
+
       await get().loadRequests();
     } catch (err) {
       set({ error: (err as Error).message, isLoading: false });
@@ -61,7 +159,12 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   updateFriendRequest: async (id: string, status: 'accepted' | 'declined') => {
     set({ isLoading: true, error: null });
     try {
-      await api.social.updateRequest(id, status);
+      // Find the request to determine which instance owns it
+      const request = get().requests.find(r => r.id === id);
+      const origin = request?._instanceOrigin ?? '';
+      const client = getApiForOrigin(origin);
+
+      await client.social.updateRequest(id, status);
       await get().loadRequests();
       if (status === 'accepted') {
         await get().loadFriends();
@@ -75,7 +178,11 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   cancelFriendRequest: async (id: string) => {
     set({ isLoading: true, error: null });
     try {
-      await api.social.cancelRequest(id);
+      const request = get().requests.find(r => r.id === id);
+      const origin = request?._instanceOrigin ?? '';
+      const client = getApiForOrigin(origin);
+
+      await client.social.cancelRequest(id);
       set((state) => ({
         requests: state.requests.filter(r => r.id !== id),
         isLoading: false,
@@ -89,9 +196,14 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   removeFriend: async (id: string) => {
     set({ isLoading: true, error: null });
     try {
-      await api.social.removeFriend(id);
+      // Find the friend to determine which instance owns it
+      const friend = get().friends.find(f => f.id === id);
+      const origin = friend?._instanceOrigin ?? '';
+      const client = getApiForOrigin(origin);
+
+      await client.social.removeFriend(id);
       set((state) => ({
-        friends: state.friends.filter((f) => f.id !== id),
+        friends: state.friends.filter(f => !(f.id === id && f._instanceOrigin === origin)),
         isLoading: false,
       }));
     } catch (err) {
@@ -102,7 +214,27 @@ export const useSocialStore = create<SocialState>((set, get) => ({
 
   searchUsers: async (query: string) => {
     try {
-      return await api.social.search(query);
+      const instances = useInstanceStore.getState().instances;
+      const connectedInstances = instances.filter(i => i.status === 'connected');
+
+      const results = await Promise.allSettled([
+        api.social.search(query),
+        ...connectedInstances.map(inst => inst.api.social.search(query)),
+      ]);
+
+      const allUsers: User[] = [];
+      const seen = new Set<string>();
+
+      for (const result of results) {
+        if (result.status !== 'fulfilled') continue;
+        for (const user of result.value) {
+          if (seen.has(user.id)) continue;
+          seen.add(user.id);
+          allUsers.push(user);
+        }
+      }
+
+      return allUsers;
     } catch (err) {
       console.error('Failed to search users:', err);
       return [];
@@ -110,25 +242,30 @@ export const useSocialStore = create<SocialState>((set, get) => ({
   },
 
   // Called from WS handler when another user sends you a friend request
-  addIncomingRequest: (request: FriendRequest) => {
+  addIncomingRequest: (request: FriendRequest, origin: string) => {
     set((state) => {
-      if (state.requests.find(r => r.id === request.id)) return state;
+      const key = `${request.id}:${origin}`;
-      return { requests: [...state.requests, request] };
+      if (state.requests.find(r => `${r.id}:${r._instanceOrigin}` === key)) return state;
+      return { requests: [...state.requests, { ...request, _instanceOrigin: origin }] };
     });
   },
 
   // Called from WS handler when someone accepts your friend request
-  addFriendFromAccepted: (friend: Friend, requestId: string) => {
+  addFriendFromAccepted: (friend: Friend, requestId: string, origin: string) => {
-    set((state) => ({
+    set((state) => {
-      friends: state.friends.find(f => f.id === friend.id) ? state.friends : [...state.friends, friend],
+      const key = `${friend.id}:${origin}`;
-      requests: state.requests.filter(r => r.id !== requestId),
+      const alreadyExists = state.friends.some(f => `${f.id}:${f._instanceOrigin}` === key);
-    }));
+      return {
+        friends: alreadyExists ? state.friends : [...state.friends, { ...friend, _instanceOrigin: origin }],
+        requests: state.requests.filter(r => !(r.id === requestId && r._instanceOrigin === origin)),
+      };
+    });
   },
 
   // Called from WS handler when the other user removes us as a friend
-  removeFriendLocally: (userId: string) => {
+  removeFriendLocally: (userId: string, origin: string) => {
     set((state) => ({
-      friends: state.friends.filter(f => f.id !== userId),
+      friends: state.friends.filter(f => !(f.id === userId && f._instanceOrigin === origin)),
     }));
   },