Key points for GA4 in React SPA: 1) Set send_page_view: false to prevent duplicate counts; 2) Use useLocation to track route changes and send pageviews manually; 3) Set user_id after login for cross-device tracking.
Pydantic v2 no longer supports class Config. Use model_config = ConfigDict(from_attributes=True) instead. If your model has a field named model_config, you must rename it to avoid conflict with the reserved attribute.
Vite path aliases require simultaneous configuration in both vite.config.ts and tsconfig.json—neither works alone. Vite handles bundler resolution, TypeScript handles type checking and IDE intellisense.
The key to cascade selection: when parent changes, reset child to a valid value. Use Record<string, Option[]> for type-safe data mapping, and update child state inside onValueChange callback.