Web app frontend (apps/web)

When to use: apps/web UI — routes, @repo/ui, TanStack Start server functions and collections, forms (useForm with createFormSubmitHandler + fieldErrorsAsStrings when Zod validation errors should appear on fields), Tailwind layout rules, design-system updates, and useEffect / useMountEffect policy.

Legacy UI reference

• Before building new UI, inspect the old v1 UI/components and product patterns as a reference when relevant.
• Reuse as much as possible when the old implementation is still solid.
• Do not copy v1 UI blindly; review it critically and improve it to match v2 conventions, architecture, and quality expectations when needed.

React 19

The project uses React 19. Follow modern patterns and avoid deprecated APIs:

• No forwardRef — ref is a regular prop in React 19. Declare it in the props type and destructure it directly.
• No ElementRef — use React.ComponentRef<typeof SomeComponent> instead (the ElementRef alias is deprecated).
• No gratuitous useMemo / useCallback / React.memo — the React Compiler (enabled in the build) auto-memoizes. Only add manual memoization when profiling shows a concrete bottleneck; remove existing wrappers when they have no measured benefit.
• Prefer use() for consuming promises and context where appropriate.