Desktop Google login flow: click "Continue with Google" → opens default
browser to web login page with platform=desktop → Google OAuth completes
→ web callback redirects to multica://auth/callback?token=<jwt> →
Electron receives deep link, extracts token, completes login.
Changes:
- Register `multica://` protocol in Electron (main process + builder)
- Add single-instance lock with deep link forwarding (macOS + Win/Linux)
- Expose `desktopAPI.onAuthToken` and `openExternal` via preload IPC
- Add `loginWithToken(token)` to core auth store
- Pass `state=platform:desktop` through Google OAuth flow
- Web callback detects desktop state and redirects via deep link
- Desktop renderer listens for auth token and hydrates session
- staleTime: 0 on fetchQuery after leave/delete so fresh data is fetched
- setQueryData before switchWorkspace in createWorkspace so sidebar is
consistent on first render
- seed workspaceKeys.list() cache in login, Google callback, and
settings save so the first useQuery(workspaceListOptions()) hit is free
- remove dead onError from WorkspaceStoreOptions (used only by the
deleted refreshWorkspaces action)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
The callback page was placed under app/(auth)/callback/ — a Next.js
route group — which mapped to /callback instead of /auth/callback.
Move it to app/auth/callback/ so the URL matches the Google OAuth
redirect URI.
