fix(web): joinByCode normalizes explicit home origin to local

When a caller passes the user's own instance origin (e.g. from an invite
snapshot's spaceInstanceOrigin), strip it to undefined before the remote
branch so the local api path is taken instead of erroneously failing with
NotConnectedError. Mirrors inviteParser's identical normalization.

packages/web/src/stores/spaceStore.joinByCode.test.ts

@@ -0,0 +1,92 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+// Stub AudioManager to avoid AudioWorkletNode reference error in jsdom
+vi.mock('../audio/AudioManager', () => ({
+  AudioManager: {
+    getInstance: vi.fn().mockReturnValue({
+      setOutputDevice: vi.fn(),
+      setVolume: vi.fn(),
+    }),
+  },
+}));
+
+// Stub instanceStore to avoid initialization ordering issues
+vi.mock('./instanceStore', () => ({
+  useInstanceStore: Object.assign(
+    (selector: (s: unknown) => unknown) => selector({ instances: [], _autoConnectDone: true }),
+    {
+      getState: () => ({ instances: [], _autoConnectDone: true }),
+      setState: vi.fn(),
+      subscribe: vi.fn(),
+    }
+  ),
+}));
+
+// Stub authStore to avoid localStorage access during module init
+vi.mock('./authStore', () => ({
+  useAuthStore: Object.assign(
+    (selector: (s: unknown) => unknown) => selector({ user: null, token: null }),
+    {
+      getState: () => ({ user: null, token: null }),
+      setState: vi.fn(),
+      subscribe: vi.fn(),
+    }
+  ),
+}));
+
+// Stub the api client — use vi.fn() inline (hoisting constraint)
+vi.mock('../api/client', () => ({
+  api: {
+    spaces: { joinByCode: vi.fn() },
+  },
+  BackspaceApiClient: vi.fn(),
+}));
+
+// Stub crossStoreResolvers — use vi.fn() inline
+vi.mock('../utils/crossStoreResolvers', () => ({
+  getApiForOrigin: vi.fn(),
+  resolveOriginFromHostname: vi.fn(),
+  resolveUserIdFromInstances: vi.fn(),
+  getCachedUserIdForOrigin: vi.fn(),
+  clearMyUserIdCache: vi.fn(),
+}));
+
+// Import after mocks so we get the mocked versions
+import { useSpaceStore } from './spaceStore';
+import { api } from '../api/client';
+import { getApiForOrigin } from '../utils/crossStoreResolvers';
+
+const FAKE_SPACE = {
+  id: 'S1',
+  name: 'Aether',
+  icon: null,
+  banner: null,
+  _instanceOrigin: '',
+  description: null,
+  isPublic: false,
+  isDiscoverable: false,
+  ownerId: 'U1',
+  createdAt: 1000,
+  memberCount: 1,
+};
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  useSpaceStore.getState().reset();
+  (api.spaces.joinByCode as ReturnType<typeof vi.fn>).mockResolvedValue(FAKE_SPACE);
+});
+
+describe('spaceStore.joinByCode — origin normalization', () => {
+  it('treats explicit home origin as local (does NOT call getApiForOrigin)', async () => {
+    const homeOrigin = window.location.origin;
+    await useSpaceStore.getState().joinByCode('abc', homeOrigin);
+    expect(api.spaces.joinByCode).toHaveBeenCalledTimes(1);
+    expect(getApiForOrigin).not.toHaveBeenCalled();
+  });
+
+  it('treats undefined origin as local (existing behavior preserved)', async () => {
+    await useSpaceStore.getState().joinByCode('abc');
+    expect(api.spaces.joinByCode).toHaveBeenCalledTimes(1);
+    expect(getApiForOrigin).not.toHaveBeenCalled();
+  });
+});

packages/web/src/stores/spaceStore.ts

@@ -347,6 +347,11 @@ export const useSpaceStore = create<SpaceState>((set, get) => ({
   },
 
   joinByCode: async (inviteCode: string, origin?: string) => {
+    // Normalize: an explicit home origin is equivalent to undefined (local).
+    // Mirrors inviteParser's same normalization at the URL boundary.
+    if (origin && typeof window !== 'undefined' && origin === window.location.origin) {
+      origin = undefined;
+    }
     if (origin) {
       // Remote instance — verify connectivity via dynamic import (avoids circular dep)
       const { useInstanceStore } = await import('./instanceStore');