fix: resolve duplicate voice user in federated channel sidebar

Use origin-aware user ID resolution for optimistic voice add/remove
instead of always using the home instance ID. Adds getMyUserIdForOrigin
resolver (same pattern as getApiForOrigin) so joinVoiceChannel and
leaveVoice use the correct federated user ID. Also fixes WS reconnect
voice re-registration, invite URL for remote servers, and chatStore
early-load guard for unmapped channels.

packages/web/src/stores/chatStore.ts

@@ -132,9 +132,12 @@ export const useChatStore = create<ChatState>((set, get) => ({
 
   loadMessages: async (channelId: string, force?: boolean) => {
     if (!force && get().hasMore.has(channelId)) return;
+    const isDm = isDmChannel(channelId);
+    // For server channels, bail if we don't know which instance owns this channel yet.
+    // The remote WS ready handler will call loadMessages once the map is populated.
+    if (!isDm && !useServerStore.getState().channelOriginMap.has(channelId)) return;
     set({ isLoading: true, loadError: null });
     try {
-      const isDm = isDmChannel(channelId);
       const origin = getChannelOrigin(channelId);
       const client = getApiForOrigin(origin);
       const messages = isDm

packages/web/src/stores/instanceStore.ts

@@ -2,7 +2,7 @@ import { create } from 'zustand';
 import type { User, InstanceInfoResponse, ReplicatedInstance, AuthResponse } from '@backspace/shared';
 import { BackspaceApiClient, createApiClient, api } from '../api/client';
 import { useAuthStore } from './authStore';
-import { setApiForOriginResolver, useServerStore } from './serverStore';
+import { setApiForOriginResolver, setUserIdForOriginResolver, useServerStore } from './serverStore';
 import { connectInstance, disconnectInstance, disconnectAllRemote } from '../hooks/useWebSocket';
 
 // ─── Types ───────────────────────────────────────────────────────────────────
@@ -505,3 +505,12 @@ setApiForOriginResolver((origin: string): BackspaceApiClient => {
   if (!instance) return api;
   return instance.api;
 });
+
+// ─── User ID resolution (federation) ──────────────────────────────────────────
+// Maps an origin to the local user's ID on that remote instance.
+// Used by voice join/leave to optimistically add/remove the correct user ID.
+
+setUserIdForOriginResolver((origin: string): string | undefined => {
+  const instance = useInstanceStore.getState().instances.find(i => i.origin === origin);
+  return instance?.user.id;
+});

packages/web/src/stores/serverStore.ts

@@ -144,7 +144,8 @@ export const useServerStore = create<ServerState>((set, get) => ({
     try {
       // Resolve the correct API client based on the server's instance origin
       const server = get().servers.find(s => s.id === serverId);
-      const origin = server?._instanceOrigin ?? '';
+      if (!server) return; // Not populated yet — remote WS ready will trigger reload
+      const origin = server._instanceOrigin ?? '';
       const client = getApiForOrigin(origin);
 
       const detail = await client.servers.get(serverId);
@@ -233,7 +234,10 @@ export const useServerStore = create<ServerState>((set, get) => ({
   },
 
   generateInvite: async (serverId: string) => {
-    const result = await api.servers.invite(serverId);
+    const server = get().servers.find(s => s.id === serverId);
+    const origin = server?._instanceOrigin ?? '';
+    const client = getApiForOrigin(origin);
+    const result = await client.servers.invite(serverId);
     return result.inviteCode;
   },
 
@@ -550,3 +554,23 @@ export function getApiForOrigin(origin: string): BackspaceApiClient {
   if (!origin || !_getApiForOrigin) return api;
   return _getApiForOrigin(origin);
 }
+
+// ─── User ID resolution (federation) ──────────────────────────────────────────
+// Same resolver pattern as getApiForOrigin — registered by instanceStore on
+// import to break the circular dependency chain.
+
+let _getUserIdForOrigin: ((origin: string) => string | undefined) | null = null;
+
+export function setUserIdForOriginResolver(resolver: (origin: string) => string | undefined): void {
+  _getUserIdForOrigin = resolver;
+}
+
+/**
+ * Returns the local user's ID on a given instance origin.
+ * '' or falsy = home instance (returns authStore user ID).
+ * 'https://...' = remote instance (returns the federated user ID on that instance).
+ */
+export function getMyUserIdForOrigin(origin: string): string | undefined {
+  if (!origin) return useAuthStore.getState().user?.id;
+  return _getUserIdForOrigin?.(origin);
+}

packages/web/src/stores/voiceStore.ts

@@ -2,8 +2,7 @@ import { create } from 'zustand';
 import { persist, createJSONStorage } from 'zustand/middleware';
 import type { ParticipantInfo } from '../hooks/useLiveKit';
 import { AudioManager } from '../audio/AudioManager';
-import { useServerStore } from './serverStore';
-import { useAuthStore } from './authStore';
+import { useServerStore, getChannelOrigin, getMyUserIdForOrigin } from './serverStore';
 
 export interface ScreenShareConfig {
   height: 1080 | 720 | 540;
@@ -294,7 +293,7 @@ export const useVoiceStore = create<VoiceState>()(
       // Leave voice without wiping the voiceUsers map (so sidebar still shows others)
       leaveVoice: () => {
         const channelId = get().currentVoiceChannelId;
-        const myId = useAuthStore.getState().user?.id;
+        const myId = channelId ? getMyUserIdForOrigin(getChannelOrigin(channelId)) : undefined;
 
         set((state) => {
           // Optimistic: immediately remove self from the channel's voice users