Shadcn Guideline: Patterns — Combine with React Hook Form. Description: Form + useForm for complete forms. Do: RHF Controller with shadcn inputs. Don't: Custom form state management. Good Example: <FormField control={form.control} name="email">. Bad Example: <Input value={email} onChange={(e) => setEmail(e.target.value)}. Severity: High. Docs: https://ui.shadcn.com/docs/components/form.